CA1087423A - Low expansion low resistivity composite powder metallurgy member - Google Patents
Low expansion low resistivity composite powder metallurgy memberInfo
- Publication number
- CA1087423A CA1087423A CA304,871A CA304871A CA1087423A CA 1087423 A CA1087423 A CA 1087423A CA 304871 A CA304871 A CA 304871A CA 1087423 A CA1087423 A CA 1087423A
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- Prior art keywords
- metal powder
- iron
- less
- nickel
- copper
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
- H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
- H01L23/495—Lead-frames or other flat leads
- H01L23/49579—Lead-frames or other flat leads characterised by the materials of the lead frames or layers thereon
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/09—Mixtures of metallic powders
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/02—Making ferrous alloys by powder metallurgy
- C22C33/0207—Using a mixture of prealloyed powders or a master alloy
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
- H01L21/4814—Conductive parts
- H01L21/4821—Flat leads, e.g. lead frames with or without insulating supports
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/095—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00 with a principal constituent of the material being a combination of two or more materials provided in the groups H01L2924/013 - H01L2924/0715
- H01L2924/097—Glass-ceramics, e.g. devitrified glass
- H01L2924/09701—Low temperature co-fired ceramic [LTCC]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12014—All metal or with adjacent metals having metal particles
- Y10T428/1216—Continuous interengaged phases of plural metals, or oriented fiber containing
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- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Chemical & Material Sciences (AREA)
- General Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Computer Hardware Design (AREA)
- Physics & Mathematics (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Powder Metallurgy (AREA)
- Lead Frames For Integrated Circuits (AREA)
Abstract
ABSTRACT
A compacted article having low thermal expansivity and high thermal conductivity is made by compacting a mixture of two metal powders, one of which has low thermal expansivity and the other of which has high thermal conductivity, and strip material made therefrom which is suitable for use in forming the supportive lead frames in integrated circuit components. The powders are mixed together, formed into a green compact, sintered, and rolled to size to produce strip which has a unique combination of lot;
thermal expansivity and high thermal conductivity. A low-expan-ivity metal disclosed is an alloy containing about 45-70% iron, 20-55% nickel, up to 25% cobalt, and up to 5% chromium which in powder form is mixed with a high-conductivity metal powder disclosed as substantially elemental iron, copper or nickel.
A compacted article having low thermal expansivity and high thermal conductivity is made by compacting a mixture of two metal powders, one of which has low thermal expansivity and the other of which has high thermal conductivity, and strip material made therefrom which is suitable for use in forming the supportive lead frames in integrated circuit components. The powders are mixed together, formed into a green compact, sintered, and rolled to size to produce strip which has a unique combination of lot;
thermal expansivity and high thermal conductivity. A low-expan-ivity metal disclosed is an alloy containing about 45-70% iron, 20-55% nickel, up to 25% cobalt, and up to 5% chromium which in powder form is mixed with a high-conductivity metal powder disclosed as substantially elemental iron, copper or nickel.
Description
SPECIFICATION
This inven-tion relates to metallic articles including those suitable for making strip and, more particularly, to such articles made by powder metallurgy techniques having a unique combination of thermal and electrical properties and especially well suited for making lead frames of the type used in integrated circuits.
A lead frame is a thin metal structure on which an integrated circuit chip is mounted. It serves as means for supporting the chip and for electrically connecting the chip to other components. After the chip has been attached to the lead frame, it is generally sealed in an insulative and protective material such as a glass, ceramic or plastic, with the lead frame extending through the sealing material to provide con~ection with the chip.
It is desirable that the metal strip material from which the lead frames are produced have a certain unique combinatio of properties to enable the efficient manufacture of these compo-nents, particularly in mass production. The thermal expansion of the lead frame material should be matched to that of the sealing material over the temperature range at which it is sealed. The general range of thermal expansion coefficients desired for the lead frame material is about 4 to 12 x 10 6/oC averaged over the temperature range of about 25C to about 400C, which is a rela-- tively low expansivity for alloys. Furthermore, it is desirable to provide lead frame material with sufficiently low thermal expansivity to allow direct attachment of the silicon chip, which has low expansivity, using eutectic soldering methods wherein the chip and fr me are normally heated to about 400C and whe~eln it .
~ ~ .
7~ 3 is important that the chip and frame have approximately the same expansivity. In accordance with the common practice, hereinafter when an expansion coefficient is given at a certain temperature, it is intended to mean the average expansion coefficient over the temperature range of 25C to that temperature.
Another important lead Erame property in integrated circuit component manufacture is a relatively high thermal ~onductivity. ThiS is necessary for heat transfer away from the silicon chip duxing manufacturing steps such as soldering or 10 brazing as well as during operation of the integrated circuits -~
some of which operate at relatively high power levels. Other desired properties include solderability and sufficient stampabil-ity and ductility to permit forming and to resist failure from bending fatigue.
; Iron-nickel and iron-nickel-cobalt low-expansion alloys with thermal expansion coefficients below 10 x 10 6/oC at 400C -have been used for lead frame strip because of their low expan-sivity. One commonly used material is a 42% nickel iron-nickel al:loy which combines low thermal expansivity with good solder-ability, ductility, and stampability. However, these low-expansion alloys leave much to be desired because of their relatively high cost because of the high nickel content and their rela-i tively low thermal conductivity. One method of overcoming the thermal conductivity problem has been to plate the lead frame with silver which can increase the conductivity to the desired ~;
level. However, this is an expensive practice which significantly increases the cost of articles made from these already expensive nickel alloys.
It is, therefore, a principal object of this invention 30 to provide a compacted article suitable for making lead frame strip material which combines low thermal expansivity with high thermal conductivity.
It is a further object of this invention to provide such a compacted article which also has suitable solderability, ductility, and formability, including stampability, for lead frame applications.
Another object is to provide an improved process for making articles having a unique combination of thermal and electrical properties.
The foregoing as well as additional objects and advantages of the present invention are achieved by providing a compacted article, suitable for making composite lead frame strip material, which i5 prepared from a mixture of a low thermal expansivity alloy powder and a powdered metal or alloy .~ , ~':
~8'~ 3 of high thermal conductivity. The powders ~re blended, formedinto a compacted article, preferably of substantially theoretical density and further shaped as desired. Preferably, the compacted article is rolled to form lead fr~me strip material. By control-ling heating time and temperature, as well as other process variables, care is taken throughout the forming process to insure that the amount of alloying between the ~a~ticles of the low thermal expansivity alloy powder and the high thermal conductivity metal is minimized to that which is necessary to bind the powders into a suitably coherent article or strip material.
The present invention will now be described in detail in accordance with a preferred embodiment thereof for forming lead frame strip material. Two complementary powdered metals, one of which has low thermal expansivity and the other of which has high thermal conductivity are thoroughly mixed or blended. The selection of the low~expansivity metal depends in part on the expansivity of the complementary high-conductivity metal and on the desired expansivity of the lead frame strip.
As previously discussed, it is desired to match the expansivity of the lead frame strip with materials whose 400C thermal expansion coefficients range from about 4 to 12 x 10 6/oC and, therefore, it is preferred to provide a lead frame strip with ` an expansivity within that range, and even more preferable to provide such strip with a 400C expansion coefficient of less than about 10 x 10 6/oC. For this reason, a low-expansivity metal suitable for use with this invention should have a 400C -thermal expansion coefficient of less than about 12 x 10 6/oC, preferably less than about 10 x 10 6/oC. A class of alloys which provides the desired expansion coefficients for the low-expansivity metal are the iron-nickel and iron-nickel-cobalt controlled-expansive alloys. The predominant elements of these alloys are iron and nickel which coact to provide an austenitic microstructure, in which the cobalt may be substituted for some of the nickel. A preferred composition for alloys of this type comprises, in weight percent (w/o), about 45 to 70% iron, about 20 to 55% nickel, up to about 25% cobalt, and up to about 5%
chromium, which is balanced to provide an alloy with a 400C
thermal expansion coefficient of less than about 12 x 10 6/oC, preferably less than about 10 x 10 6/oC. Hereinafter, all ~ ;
percen~s used in alloy compositions will be by weight unless otherwise stated. ~
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When the alloy is of the iron-nickel type, without any significant amount o~ cobalt, a miniumum of 30% nickel is required, since alloys containing less nickel tend to form ferrite which greatly increases the expansivity of the alloy. As the nickel content is increased from 30%, the expansivity first decreases and then increasés, until above about 55% nickel the expansivity of the alloy becomes too high to be suitable for use as the low-expansivity metal powder of the present invention. Commonly used nickel-iron low-expansion alloys are those containing between 35 and 52 w/o nickel, the expansivity of which will be discussed further hereinbelow.
Up to about 25% cobalt may be used in addition to or in place of some of the nickel to further lower thermal expan~
sivity and to increase corrosion resistance. The nickel content can be lowered to a minimum of 20~ when enough cobalt is added to prevent the formation of ferrite and to maintain the desired low expansivityO Amounts of cobalt more than about 25~ do not significantly reduce expansivity, and simply add to the cost of the alloy.
A small amount of chromium may be added to improve corrosion resistance, but because it acts to increase expan-sivity and decrease thermal conductivity, not more than 5%
should be present.
; The thermal conductivity of a material may be char-acterized in terms of its electrical resistivity which is the inverse of electrical conductivity, which, in turn, is proportional to thermal conductivity. The high thermal conductivity metal powder ~or use in this invention has an electrical resistivity of less than about 200 ohm-circular mils per foot (ohm/cmf), which is about 33.2 microhm-~cm, and preferably less than 100 ohm/cmf (16.6 microhm-cm). Three suitable high-conductivity metals which ;
are preferred for use with this invention are substantially ele-mental iron, copper, and nickel which may contain alloying ele-ments within the limits set forth hereinbelow. A number of other elemental metals such as silver, gold, and platinum also have suitable conductivities, but are considered to be prohibitively expensive. Elemental aluminum has a suitable conductivity, but its low melting point coupled with a tendency to reduce ductility when it alloys with iron-nickel alloys makes it less suitable than 4~ the pre~erred iron, copper and nickel. :
At this time, iron is the least expensive of the three metals, with copper at least twice as expensive depending on the quality of the particular iron being considered, and with nickel - being about three times as expensive as copper. Copper has the ~ .
:- . .
lowest resistivity of the three metals, about 10 ohm/cmf (1.7 microhm-cm), with nickel at about ~1 ohm/cmf (6.8 microhm-cm), and iron (99.98% pure) at about 60 ohm/cmf (10 microhm-cm), all mea-sured at about 20C. Copper and nickel are both more corrosion resistant than iron, which is susceptible to rusting. Of the three, iron has the lowest expansivity and copper the highest, with 25C linear expansion coe~ficien-ts (x 106) per C of 12 for iron, 13 for nickel, and 16.6 for copper. Nickel offers the highest strength and hardness of the three metals, with copper having the lowest. In addition, the properties of the complementary low-expansivity alloy will also affect the determination of which high-conductivity metal is most suitable. To obtain the maximum conductivity, the amount of alloying additions and impurities should be minimized, with 99% or purer elemental metals being preferred to provide the highest conductivity. Some of the less desired properties of these high-conductivity metals may be improved by the addition of alloying elements within the following limits, but such alloying additions may result in a reduction in conductivity.
When the high-conductivity material is primarily iron, a minimum of about 90~ iron is required in the composition of the material to provide the desired conductivity. Up to about 10%
chromium can be added to improve corrosion resistance. Up to ~ -about 10% nickel can be added to improve corrosion resistance, ; and also to lower expansivity. Minor additions of copper can also be made to improve corrosion resistance, but only up to a ~-maximum of about 5~, because this is about the solubility limit of copper in iron at room temperature.
When the high-conductivity material is primarily copper, 30 a minimum of about 80% is required in the composition of the -material to provide the desired conductivity. Up to about 20%
nickel can be added to lower the expansivity. The addition of nickel also affects the characteristic reddish color of the copper which would otherwise contrast with the grey metallic color of the low-expansion metal. Up to about 20% zinc can also be added, but will slightly increase the expansivity and lower the con-ductivity of the material. An addition of aluminum can be made ~-to harden the copper alloy, with the additional benefit of a slight lowering of the expansivity. However, no more than about 10%
4Q aluminum should be added because of its adverse effect on con-ductivity. Either iron or beryllium, but not both, can be added as a strengthening agent up to a maximum of about 3~ which is the solubility limit of each in copper.
When the high-conductivity material is primarily nickel, a :'., . : ' ' ' . ' ' . ~ ' ;23 minimum of about 80% is required for the desired thermal con-ductivity. Up to about 20~ copper or iron can be added to reduce the cost of the metal with a tolerable reduction of conductivity.
The high-conductivity metal powder is combined with a low-expansivity alloy powder to provide a composite strip material with a thermal conductivity higher than that of the low-expansivity alloy and an expansivity lower than that of the high-conductivity metal. The strip material is characterized as being a composite because the two different types of powder particles which are thoroughly intermixed throughout the strip substantially remain distinct, with a minimum of alloying between particles as will be discussed further hereinafter. Preferably, the composite strip material has a resistivity of less than about 200 ohm/cmf (33 microhm-cm), and, more preferably, less than about 150 ohm/cmf (25 microhm-cm). It is even more preferable to provide strip material which also has a thermal expansivity at 400C of less than 12x10 6/oC, better yet, less than 10x10 6/oC, as well as a resistivity of less than 200 ohm/cmf, better yet, less than 150 ohm/cmf.
In making lead frame strip in accordance with this invention, complementary high-conductivity and low-expansivity powdered metals are used which will produce strip material with the desired properties. A rough estimate of the expansivity of -the composite strip can be calculated by taking the average of the ` known expansivities of the component metals, adjusting according to the volumetric proportions of each, as will be more fully dis-cussed in connection with the examples hereinafter described.
Each of the metal components is melted and formed into powder using standard techniques. Excellent results were obtained by using water~atomized powders because the irregular shape of these 30 powders lends itself to a high degree of compaction, as is well -~
known. Other techniques for providing powder, such as gas-atom-ization or chemical methods can also be used.
The two powders are then blended in proportions to obtain the desired combination of thermal conductivity and thermal ; expansivity as well as the other significant properties necessary for the final product. With a 50-50 volumetric blend of the two powders, the properties of the strip material are approximately the average for those of the component metals. When the blend com-prises more than 50 volume percent of the hish thermal conductivity powder, a minimum of 15 volume percent of the low thermal expan-sivity powder should be used to effect a significant reduction in the expansivity of the composite strip material as compared to the expansivity of the high-conductivity material. Preferably, at le~st 40 volume percent of the low-expansivity p~wder is used to . : . .
.
achieve a good balance of properties. In like manner, when more than 50 volume percent of the low-expansivity powder is used, a minimum of 15 volume percent, preferably 40 volume percent, of the high-conductivity powder should be used to obtain the desired balance of properties.
The hlended powders are then formed into an intermediate article such as slab or strip, preferably the latter, and densified to substantially theo~e-tical density using any suitable, known techniques. In one method which gave good results, the component powders are blended using known methods and are then charged into a fluidized bed having a suitable protective gas as the fluidizing medium. The blended powder is then pressed into a green preform such as a strip, which can be formed by feeding the powder into the nip of a roll compacting mill, preferably using means which feed the powder directly from the fluidized bed into the mill.
The thus-formed green preform or strip is then sintered in a suitable protective atmosphere at a temperature which is dependent on the particular component compositions. In general, ~ the sinterin~ temperature should be at least about 100F (55~C) ; 20 below the lower of the melting points of the two components, so as to minimize alloying between the components. Such alloying was found to be undesirable, as will be discussed further hereinbelow.
Similarly, sintering time should also be minimi~ed to reduce alloying with sintering times of 2 to 6 minutes giving good results.
The sintered article is then formed into lead frame strip, preferably by the following ~rocedure. First, it is cold rolled into strip of an intermediate size after which it is stress relieved by annealing in a suitable protective atmosphere.
The annealing temperature should be below that used in sintering, and, as is well known, would depend on the particular materials and procedure being used. Here again, a short annealing time is desirable and annealing for about 2 to 5 minutes gave good results.
After annealing, the strip is then cold rolled to finished size, either directly or after a series of reductions with intermediate ; anneals as required. In commercial-scale operation, each reduction is preferably about 5 to 40~ and, more preferably, about 10 to 30~, although for the small laboratory-scale examples given hereinbelow, reductions of 30-50% and larger were used.
.:
Examples 1-3 ~-Examples 1-3, illustrati~e of lead frame strip materials made in accordance with the present invention, were made as follows: The low-expansivity metals used were 42% nickel and 50~
nickel iron-nickel alloys, designated herein as Alloy A and Alloy . - . ~ , . : . - .- . . : : ~ . .
7~23 s, respectively. Each alloy was prepared according to standard melting procedure, and water atomized into powder, the compositions of which are given in Table I and the mesh fraction analyses of which are given in Table II.
TABLE I
Alloy A Alloy B
Carbon 0.022 0.021 Manganese0.42 -- -Silicon 0.15 0.019 Sulfur 0.013 0.016 Nickel 41.3~ 49.2 Copper 0.19 --Cobalt 0.13 --Iron Bal. Bal. . .
For convenience, the mesh fraction analyses of the higher conductivity iron and copper powder components arè also given in . Table II. In Table II, for each sieve, the U.S. Sieve Series designations and mesh openings in micrometers are given with the percent of each size powder held by that sieve, and the percent oE powder which passed through the last sieve in each analysis : indicated as -200 or -325. The absence.of an amount for a particular sieve indicates that that sieve was not used in that .
analysis. .
TABLE II
. .
l Pi ircent hel~ by Siev e :
Siev~ No.Opening ..
(U-S-) (llm)Alloy AAlloy B_IronCopper 420 1.1 __ __ __ :
250 6.4 __ O __ ;
~0 177 13.3 __ 4.0 __ -::
100 149 8.4 2 7.0 __ 140 105 14.9 17 16.0 __ :~
200 74 21.1 25 21.0 5 -:
-200 __ __ __ __ g5 230 63 __ __ 9.0 __ : .
325 44 17.4 28 18.0 __ -325 __ 17~5 28 25.0 __ Ll lZ 100% lOO.OZ 100%
The high-conductivity metals used in these examples were water atomized commerically pure iron powder and electrolytic commercially pure copper powder. The iron powder had a chemical analysis of 99.1 w/o iron, with 0.06 w/o carbon, 0.20 w/o manganese 0.05 w/o silicon, 0. 008 w/o phosphorus, 0.015 w/o sulfur, and the balance being incidental impurities. The copper powder : -contained 99.5 w/o copper, with 0.05 w/o iron, 0.03 w/o lead, ~-~ 0.01 w/o sulEur, 0.08 w/o acid insoluble impurities, and charac--` terized by a loss in hyd.rogen of 0.28 w/o (A.S.T.M. E-159). The .
7~L;Z3 sieve analyses of these powders is given in Table II, with the copper powder simply indicated as 5~ +200 mesh and the balance -200 mesh.
Example 1 was prepared as a 50/50 w/o mixture of -230 mesh copper powder and -40 mesh Alloy A powder, equivalent to about 48 volume percent copper powder. Example 2 was prepared as a 50/50 w/o mixture of +100 mesh iron powder and -40 mesh Alloy A powder, and Example 3 as a 50/50 w/o mixture of +100 mesh iron powder and -100 mesh Alloy B powder, both these exam-ples being equivalent to about 51 volume percent iron powder.
Each mixture was blended one hour in a ball mill blender and then compacted at 99 thousand pounds per square inch (ksi) in a hydraulic press to coupons 2 inches by 1-1/2 inches by about 0.20 inch thick t5-1 cm x 3.8 cm x 5.1 mm). The compacts of Examples 2 and 3 were then sintered at 2300F (1260C) while the compact of Example 1 containing the lower melting point copper was sintered at 1850F (1010C), all three being sin-tered for about 3 minutes in a hydrogen atmosphere. The sin-tered compacts were cold rolled to about 0.10 inch (2.54 mm) thick or about a 50~ reduction and resintered as before. Each was then cold rolled to OoO10 inch ~0.254 mm) thick strip, a commonly used size for lead frames, with intermediate anneals as required. In each case, annealing was carried out in a dissociated ammonia atmosphere at about 1900F (1040C) for Examples 2 and 3 and at about 1650F (900~C) for Example 1.
Specimens of Examples 1-3 were made from the 0.010 inch thick strip for thermal expansion and electrical resis-tivity tests, the measured results of which are given in Table III in the first line for each example designated "meas.". The components of each Example are indicated under each example number, Cu or Fe for the copper or iron powders, and A or B for the powders of Alloys A or B. In addition, parallel values, designated "calc.", for the expansion coefficients are given for each example calculated by taking the average of the coef-ficients of the two components adjusted according to the volume percent of each in the composite. It should be noted that the ~` -properties for iron came from the National Bureau of Standards publication "Mechanical and Physical Properties of Metals and Alloys" and those for copper from an NBS data sheet on standard -~
copper rather than from experimental measurement. ~
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TABLE III
Thermal Expansion Coe~ficients Electrical (10 ¦C) from 25~C to Resistivit 100C 200C 300C 400C 500~C Q= f Ex. 1 meas. 9.4 10.511.0 11.4 12.1 134 22.3 (Cu+A) calc. 10.8ll.o11.111.8 12.9 __ __ Ex. 2 meas. 7.27.9 8.3 9.2 10 3 167 27.8 (Fe+A) calc. 8.79.0 9.310.0 11.3 __ __ Ex. 3 meas. 8.79.6 10.5ll.Z 11.7 164 27 3 (Fe~B) calc. 10.511.111.411.6 12.2 __ _ Alloy A 5.25.0 5.0 5.9 7.9 40066.5 Alloy B 8.79.4 9.3 9.1 9.7 29048.2 Copper 16.9 17.4 17.818.1 18.4 10 1.7 Iron 12.2 12.8 13.413.9 14.5 60 10.0 Examples 1-3 all had the unique combination of -low expansivity and high conductivity characteristic of this invention. Example 1, prepared from copper and Alloy A powders, had a lower resistivity (higher conductivity) than Example 2 pr.epared from iron and Alloy A powders, while Example 2 had a lower expansivity than Example 1. The differences in these properties of Examples 1 and 2 reflect the lower resistivity and higher expansivity of copper compared to iron, and illustrates ~ `
how the properties of the composite strip depend on those of its component powders, and, more particularly, the effect ~ of using different high-conductivity metal powders with the same ; low-expansivity alloy powder. Example 2, prepared from iron and -40 mesh Alloy A powders had a lower expansivity and slightly higher resisitivity than Example 3 which was prepared from iron and -100 mesh Alloy B powders. In this case, different low-expansivity alloy powder components were combined with the same high-conductivity iron powder, and the differences in expansivity and resistivity of Examples 2 and 3 reflect the differences in those properties between Alloys A and B. However, although ;
Alloy B has a much lower resistivity than Alloy A, 290 ohm/cmf as compared to 400 ohm/cmf, it can be seen that the resistivity of Example 3 is only slightly lower than that of Example 2, 164 ohm/cmf as compared to 167 ohm/cmf. This is believed to be at least partly the result of the coarser particle size distribution ` of the -40 mesh Alloy A powder as compared to the -100 mesh 40 Alloy B powderr and serves to illustrate the effect of the ~ ~-particle size distributions of the component powders on the properties of the composite strip, as will be ~iscussed further hereinbelow.
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.
~7~Z3 Another disirable feature of the present invention shown by Examples 1-3 is that the thermal expansivities of the composite strips were unexpectedly lower than those calculated for the strips as can be seen by comparing the measured values with the calculated values in Table III. The reason for these lower measurements is not fullyunderstood, but is believed to be at least partly the result of some of the nickel in the lower expansivity alloy powder diffusing into the higher expansivity metal powder which would result in the lowering of the expansivity of both powders.
Examples 4-11 As ad~itional illustrations of the present invention and to show the effects of certain process variables on the -properties of the composite strip material, Examples 4-11 were made from mixtures of Alloy A powder and copper or iron powder as summarized in Table IV below. The component powders were the same as those previously described in connection with Examples 1-3. Each of the Examples 4-11 was a 50 w/o mixture o~ Alloy A powder with the elemental metal powder indicated in Table IV. The mesh sizes given in Table IV, either -230 (fine) or +100 (coarse), are the sizes to which the component powders for each example were sieved before mixing, having started with the particle size distributions as given in Table II. In addition, the sintering time in hours and the sintering temperature are also given for each example.
TAsLE IV
~ .
: ~ : : :
Sintering Treatment Metal Mesh , Time I Temp. Temp.
Ex. No. Component Size ~ (hrs)¦ (DF) (~C~
4 Copper+100 1 0.05 1800 9~2 .
Copper-230 1 0.05 1800 982 6 Copper+100 1 1 18751024 : ~
7 Copper-230 1 1 18751024 :-~ ~ :
I .:
8 Iron+100 0.05 20501~21 :
: 9 Iron-230 0.05 20501121 : :
Iron+100 1 21501177 :. :
11 Iron-230 1 21501177 Each mixture of powders was blended for 1/2 hour and compacted at room temperature and 132 ksi into c~lindrical 40 coupons 2 inches in diameter and 0.2 inches thick, one coupon ;~
being made ~or each example. Each coupon was then sintered in .:
. .
11 ., ,,' ,. - . . ~ :
7~Z3 a dry hydrogen atmosphere at the temperature and for the time indicated for each example in Table IV. The sintered compacts were cold rolled 30 to 50%, with the amount of reduction given each compact being determined by its edge and surface integrity during rolling. After removing the checked edges, the samples were annealed and cold rolled t~ a suitable thickness, 0.060-0.1 inch, for preparing thermal expansion specimens. These were cut to 2 inch long and 0.25 inch wide specimens and annealed for 1/2 hour at 1150~ ~or the copper/Alloy A specimens and 1600F for the iron/Alloy A specimens. The ther.~al expansion of each example was then measured on a recording dilatometer, with the average thermal expansion coefficient (10 6/oC) for each example from 25C to 400C given in Table V. The samples were again trimmed and cold rolled to a thickness suitable for electrical resistivity measurements, 0.010-0.020 inch thick. -After annealing, as above, the electrical resistivities were measured and are given in Table V in ohm/cmf. Specimens of these samples were then cold rolled to 0.013 inch thick, annealed at 1875F in NH3 and cold rolled to 0.010 inch thick for mechanical property tests. $his uniform treatment was used for both the iron and copper-containing samples, although it will be recognized that for particular compositions, trea~ments can be readily determined by well-known metallurgical procedures to optimize desired mechanical properties. Bend tests were performed in both the transverse and longitudinal directions on specimens of Examples 8 and 9, the results as shown in Table ~ being the average number of 90 bends to failure in 3 tests on each strlp.
TABLE V
Exp. Coeff.¦ Elect. ~ Bend Tests t 25-400C Resis. No. to Failure Ex. No. (lo-6/~C) Q/cmf I Tran., Long. ~
. :
~ 411.96 35 __ __ ; 511.95 120 __ __ 611.93 98 __ __ 712.64 174 __ __ 89.85 117 8 4 , 910.98 163 4.3 1.7 -~
1010.02 150 __ __ 1112.33 208 __ __ ~;
`: :
. .
. .. . . . .
In general, a better combination of low expansivity and low resistivity (high conduc~ivity) was obtained in both the copper-containing and iron-containing Examples which were formed from the coarser component powders with sintering at the lower temperatures for the shorter times. This can be seen by comparing Example 4 with Exa~ple 7 of the copper-containing strips and Example 8 with Example ll of the iron-containing strips. The factors which are tested here, coarser powders, lower sintering temperature, and shorter sintering time, are all believed to reduce the amount of alloying between the powder particles in the strip material. By minimizing the alloying between the component powders in the composite strip, a better combination of expansivity and conductivity is provided.
The bend tests results indicate that strip made from coarser powders (Example 8) is more ductile than that made from finer powders (Example 9). In addition, the strip of Example 8 also had a better ductility than one made from Alloy A alone, which had corresponding average bend test results of 6 trans-versely and 4.7 longitudinally. Similar tests done on copper/ -ALloy A samples also indicated that coarser powders produce more ductile strip. This higher ductility can be an important factor because it is often necessary to bend lead frames formed from this strip several times during the manufacture of integrated ~ -circuit components.
Tensile test specimens were prepared from the 0.010 inch thick strip samples, and ultimate tensile strength (UTS), percent elongation (% El.) in a 2-inch length and hardness (Rockwell Rb) were determined, The results are shown in Table VI, with parallel results for a sample prepared from Alloy A
alone also given for comparison.
TABLE VI
. '::
UTS Hardness Ex. No. (~si~ %E1 4 61 1.668 96 2.184 1 ;
6 79 1.868 7 102 2.384 ! ': ' 8 88 2.1~2 9 118 2.286 91 2.681 123 2.6 _ 8~ !
Alloy A 1 1_2_¦ 5.1 1 80 Higher strengths, elongations and hardness were obtained from those samples made from the finer powders (Examples 5, 7, 9 .. ' ~ :
:' ..
~; ~ :, ' ,, ,' ' . - . , : . - . ' .
, . , . . , . ., :
7~3 and ll) as compared to those made from coarser powders (Examples 4/ 6, a and lO), with the iron/ Alloy A samples (Examples 8-ll) higher than the corresponding copper/Alloy A samples (Examples 4-7). As previously discussed, all of these examples were prepared with the same finishing treatment which may not be the best treatmen-t for obtaining optimum mechanical properties for these particular samples.
The low-expansivity metal powders and high conductivity metal pcwders in the above examples each consisted of a single ~lO substantially homogeneous composition. It is also contemplated that the compacted article in accordance with the present invention can also be made from klends of powders in which the component low expansivity powders and/or the high conductivity powders are themselves blends of two or more different metal powders, which can be either elemental or pre-alloyed powders as required to provide the desired properties.
; Furthermore, compacted articles made in accordance with the present invention can also include additional material other than the low expansivity and high conductivity powders, provided that care is taken to insure that the desired expan-sivity and conductivity are obtained in the final product.
It is recognized that the method and product of the present invention will have a wide variety of uses, and it is not intended by reference to the substantially theoretical density of the compacted article to thereby restrict the scope ; of the present invention. In its preferred form, the present invention provides compacted articles having a density greater ; than 95% of theoretical and densities of about 99~ or better are ~
readily attained. It is also contemplated that, when desired, -compacted articles of lower density can also be provided.
The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.
.~ ' . .
.
- -:
This inven-tion relates to metallic articles including those suitable for making strip and, more particularly, to such articles made by powder metallurgy techniques having a unique combination of thermal and electrical properties and especially well suited for making lead frames of the type used in integrated circuits.
A lead frame is a thin metal structure on which an integrated circuit chip is mounted. It serves as means for supporting the chip and for electrically connecting the chip to other components. After the chip has been attached to the lead frame, it is generally sealed in an insulative and protective material such as a glass, ceramic or plastic, with the lead frame extending through the sealing material to provide con~ection with the chip.
It is desirable that the metal strip material from which the lead frames are produced have a certain unique combinatio of properties to enable the efficient manufacture of these compo-nents, particularly in mass production. The thermal expansion of the lead frame material should be matched to that of the sealing material over the temperature range at which it is sealed. The general range of thermal expansion coefficients desired for the lead frame material is about 4 to 12 x 10 6/oC averaged over the temperature range of about 25C to about 400C, which is a rela-- tively low expansivity for alloys. Furthermore, it is desirable to provide lead frame material with sufficiently low thermal expansivity to allow direct attachment of the silicon chip, which has low expansivity, using eutectic soldering methods wherein the chip and fr me are normally heated to about 400C and whe~eln it .
~ ~ .
7~ 3 is important that the chip and frame have approximately the same expansivity. In accordance with the common practice, hereinafter when an expansion coefficient is given at a certain temperature, it is intended to mean the average expansion coefficient over the temperature range of 25C to that temperature.
Another important lead Erame property in integrated circuit component manufacture is a relatively high thermal ~onductivity. ThiS is necessary for heat transfer away from the silicon chip duxing manufacturing steps such as soldering or 10 brazing as well as during operation of the integrated circuits -~
some of which operate at relatively high power levels. Other desired properties include solderability and sufficient stampabil-ity and ductility to permit forming and to resist failure from bending fatigue.
; Iron-nickel and iron-nickel-cobalt low-expansion alloys with thermal expansion coefficients below 10 x 10 6/oC at 400C -have been used for lead frame strip because of their low expan-sivity. One commonly used material is a 42% nickel iron-nickel al:loy which combines low thermal expansivity with good solder-ability, ductility, and stampability. However, these low-expansion alloys leave much to be desired because of their relatively high cost because of the high nickel content and their rela-i tively low thermal conductivity. One method of overcoming the thermal conductivity problem has been to plate the lead frame with silver which can increase the conductivity to the desired ~;
level. However, this is an expensive practice which significantly increases the cost of articles made from these already expensive nickel alloys.
It is, therefore, a principal object of this invention 30 to provide a compacted article suitable for making lead frame strip material which combines low thermal expansivity with high thermal conductivity.
It is a further object of this invention to provide such a compacted article which also has suitable solderability, ductility, and formability, including stampability, for lead frame applications.
Another object is to provide an improved process for making articles having a unique combination of thermal and electrical properties.
The foregoing as well as additional objects and advantages of the present invention are achieved by providing a compacted article, suitable for making composite lead frame strip material, which i5 prepared from a mixture of a low thermal expansivity alloy powder and a powdered metal or alloy .~ , ~':
~8'~ 3 of high thermal conductivity. The powders ~re blended, formedinto a compacted article, preferably of substantially theoretical density and further shaped as desired. Preferably, the compacted article is rolled to form lead fr~me strip material. By control-ling heating time and temperature, as well as other process variables, care is taken throughout the forming process to insure that the amount of alloying between the ~a~ticles of the low thermal expansivity alloy powder and the high thermal conductivity metal is minimized to that which is necessary to bind the powders into a suitably coherent article or strip material.
The present invention will now be described in detail in accordance with a preferred embodiment thereof for forming lead frame strip material. Two complementary powdered metals, one of which has low thermal expansivity and the other of which has high thermal conductivity are thoroughly mixed or blended. The selection of the low~expansivity metal depends in part on the expansivity of the complementary high-conductivity metal and on the desired expansivity of the lead frame strip.
As previously discussed, it is desired to match the expansivity of the lead frame strip with materials whose 400C thermal expansion coefficients range from about 4 to 12 x 10 6/oC and, therefore, it is preferred to provide a lead frame strip with ` an expansivity within that range, and even more preferable to provide such strip with a 400C expansion coefficient of less than about 10 x 10 6/oC. For this reason, a low-expansivity metal suitable for use with this invention should have a 400C -thermal expansion coefficient of less than about 12 x 10 6/oC, preferably less than about 10 x 10 6/oC. A class of alloys which provides the desired expansion coefficients for the low-expansivity metal are the iron-nickel and iron-nickel-cobalt controlled-expansive alloys. The predominant elements of these alloys are iron and nickel which coact to provide an austenitic microstructure, in which the cobalt may be substituted for some of the nickel. A preferred composition for alloys of this type comprises, in weight percent (w/o), about 45 to 70% iron, about 20 to 55% nickel, up to about 25% cobalt, and up to about 5%
chromium, which is balanced to provide an alloy with a 400C
thermal expansion coefficient of less than about 12 x 10 6/oC, preferably less than about 10 x 10 6/oC. Hereinafter, all ~ ;
percen~s used in alloy compositions will be by weight unless otherwise stated. ~
,' ~ ."'.
~::
.
,~ . , . . :
When the alloy is of the iron-nickel type, without any significant amount o~ cobalt, a miniumum of 30% nickel is required, since alloys containing less nickel tend to form ferrite which greatly increases the expansivity of the alloy. As the nickel content is increased from 30%, the expansivity first decreases and then increasés, until above about 55% nickel the expansivity of the alloy becomes too high to be suitable for use as the low-expansivity metal powder of the present invention. Commonly used nickel-iron low-expansion alloys are those containing between 35 and 52 w/o nickel, the expansivity of which will be discussed further hereinbelow.
Up to about 25% cobalt may be used in addition to or in place of some of the nickel to further lower thermal expan~
sivity and to increase corrosion resistance. The nickel content can be lowered to a minimum of 20~ when enough cobalt is added to prevent the formation of ferrite and to maintain the desired low expansivityO Amounts of cobalt more than about 25~ do not significantly reduce expansivity, and simply add to the cost of the alloy.
A small amount of chromium may be added to improve corrosion resistance, but because it acts to increase expan-sivity and decrease thermal conductivity, not more than 5%
should be present.
; The thermal conductivity of a material may be char-acterized in terms of its electrical resistivity which is the inverse of electrical conductivity, which, in turn, is proportional to thermal conductivity. The high thermal conductivity metal powder ~or use in this invention has an electrical resistivity of less than about 200 ohm-circular mils per foot (ohm/cmf), which is about 33.2 microhm-~cm, and preferably less than 100 ohm/cmf (16.6 microhm-cm). Three suitable high-conductivity metals which ;
are preferred for use with this invention are substantially ele-mental iron, copper, and nickel which may contain alloying ele-ments within the limits set forth hereinbelow. A number of other elemental metals such as silver, gold, and platinum also have suitable conductivities, but are considered to be prohibitively expensive. Elemental aluminum has a suitable conductivity, but its low melting point coupled with a tendency to reduce ductility when it alloys with iron-nickel alloys makes it less suitable than 4~ the pre~erred iron, copper and nickel. :
At this time, iron is the least expensive of the three metals, with copper at least twice as expensive depending on the quality of the particular iron being considered, and with nickel - being about three times as expensive as copper. Copper has the ~ .
:- . .
lowest resistivity of the three metals, about 10 ohm/cmf (1.7 microhm-cm), with nickel at about ~1 ohm/cmf (6.8 microhm-cm), and iron (99.98% pure) at about 60 ohm/cmf (10 microhm-cm), all mea-sured at about 20C. Copper and nickel are both more corrosion resistant than iron, which is susceptible to rusting. Of the three, iron has the lowest expansivity and copper the highest, with 25C linear expansion coe~ficien-ts (x 106) per C of 12 for iron, 13 for nickel, and 16.6 for copper. Nickel offers the highest strength and hardness of the three metals, with copper having the lowest. In addition, the properties of the complementary low-expansivity alloy will also affect the determination of which high-conductivity metal is most suitable. To obtain the maximum conductivity, the amount of alloying additions and impurities should be minimized, with 99% or purer elemental metals being preferred to provide the highest conductivity. Some of the less desired properties of these high-conductivity metals may be improved by the addition of alloying elements within the following limits, but such alloying additions may result in a reduction in conductivity.
When the high-conductivity material is primarily iron, a minimum of about 90~ iron is required in the composition of the material to provide the desired conductivity. Up to about 10%
chromium can be added to improve corrosion resistance. Up to ~ -about 10% nickel can be added to improve corrosion resistance, ; and also to lower expansivity. Minor additions of copper can also be made to improve corrosion resistance, but only up to a ~-maximum of about 5~, because this is about the solubility limit of copper in iron at room temperature.
When the high-conductivity material is primarily copper, 30 a minimum of about 80% is required in the composition of the -material to provide the desired conductivity. Up to about 20%
nickel can be added to lower the expansivity. The addition of nickel also affects the characteristic reddish color of the copper which would otherwise contrast with the grey metallic color of the low-expansion metal. Up to about 20% zinc can also be added, but will slightly increase the expansivity and lower the con-ductivity of the material. An addition of aluminum can be made ~-to harden the copper alloy, with the additional benefit of a slight lowering of the expansivity. However, no more than about 10%
4Q aluminum should be added because of its adverse effect on con-ductivity. Either iron or beryllium, but not both, can be added as a strengthening agent up to a maximum of about 3~ which is the solubility limit of each in copper.
When the high-conductivity material is primarily nickel, a :'., . : ' ' ' . ' ' . ~ ' ;23 minimum of about 80% is required for the desired thermal con-ductivity. Up to about 20~ copper or iron can be added to reduce the cost of the metal with a tolerable reduction of conductivity.
The high-conductivity metal powder is combined with a low-expansivity alloy powder to provide a composite strip material with a thermal conductivity higher than that of the low-expansivity alloy and an expansivity lower than that of the high-conductivity metal. The strip material is characterized as being a composite because the two different types of powder particles which are thoroughly intermixed throughout the strip substantially remain distinct, with a minimum of alloying between particles as will be discussed further hereinafter. Preferably, the composite strip material has a resistivity of less than about 200 ohm/cmf (33 microhm-cm), and, more preferably, less than about 150 ohm/cmf (25 microhm-cm). It is even more preferable to provide strip material which also has a thermal expansivity at 400C of less than 12x10 6/oC, better yet, less than 10x10 6/oC, as well as a resistivity of less than 200 ohm/cmf, better yet, less than 150 ohm/cmf.
In making lead frame strip in accordance with this invention, complementary high-conductivity and low-expansivity powdered metals are used which will produce strip material with the desired properties. A rough estimate of the expansivity of -the composite strip can be calculated by taking the average of the ` known expansivities of the component metals, adjusting according to the volumetric proportions of each, as will be more fully dis-cussed in connection with the examples hereinafter described.
Each of the metal components is melted and formed into powder using standard techniques. Excellent results were obtained by using water~atomized powders because the irregular shape of these 30 powders lends itself to a high degree of compaction, as is well -~
known. Other techniques for providing powder, such as gas-atom-ization or chemical methods can also be used.
The two powders are then blended in proportions to obtain the desired combination of thermal conductivity and thermal ; expansivity as well as the other significant properties necessary for the final product. With a 50-50 volumetric blend of the two powders, the properties of the strip material are approximately the average for those of the component metals. When the blend com-prises more than 50 volume percent of the hish thermal conductivity powder, a minimum of 15 volume percent of the low thermal expan-sivity powder should be used to effect a significant reduction in the expansivity of the composite strip material as compared to the expansivity of the high-conductivity material. Preferably, at le~st 40 volume percent of the low-expansivity p~wder is used to . : . .
.
achieve a good balance of properties. In like manner, when more than 50 volume percent of the low-expansivity powder is used, a minimum of 15 volume percent, preferably 40 volume percent, of the high-conductivity powder should be used to obtain the desired balance of properties.
The hlended powders are then formed into an intermediate article such as slab or strip, preferably the latter, and densified to substantially theo~e-tical density using any suitable, known techniques. In one method which gave good results, the component powders are blended using known methods and are then charged into a fluidized bed having a suitable protective gas as the fluidizing medium. The blended powder is then pressed into a green preform such as a strip, which can be formed by feeding the powder into the nip of a roll compacting mill, preferably using means which feed the powder directly from the fluidized bed into the mill.
The thus-formed green preform or strip is then sintered in a suitable protective atmosphere at a temperature which is dependent on the particular component compositions. In general, ~ the sinterin~ temperature should be at least about 100F (55~C) ; 20 below the lower of the melting points of the two components, so as to minimize alloying between the components. Such alloying was found to be undesirable, as will be discussed further hereinbelow.
Similarly, sintering time should also be minimi~ed to reduce alloying with sintering times of 2 to 6 minutes giving good results.
The sintered article is then formed into lead frame strip, preferably by the following ~rocedure. First, it is cold rolled into strip of an intermediate size after which it is stress relieved by annealing in a suitable protective atmosphere.
The annealing temperature should be below that used in sintering, and, as is well known, would depend on the particular materials and procedure being used. Here again, a short annealing time is desirable and annealing for about 2 to 5 minutes gave good results.
After annealing, the strip is then cold rolled to finished size, either directly or after a series of reductions with intermediate ; anneals as required. In commercial-scale operation, each reduction is preferably about 5 to 40~ and, more preferably, about 10 to 30~, although for the small laboratory-scale examples given hereinbelow, reductions of 30-50% and larger were used.
.:
Examples 1-3 ~-Examples 1-3, illustrati~e of lead frame strip materials made in accordance with the present invention, were made as follows: The low-expansivity metals used were 42% nickel and 50~
nickel iron-nickel alloys, designated herein as Alloy A and Alloy . - . ~ , . : . - .- . . : : ~ . .
7~23 s, respectively. Each alloy was prepared according to standard melting procedure, and water atomized into powder, the compositions of which are given in Table I and the mesh fraction analyses of which are given in Table II.
TABLE I
Alloy A Alloy B
Carbon 0.022 0.021 Manganese0.42 -- -Silicon 0.15 0.019 Sulfur 0.013 0.016 Nickel 41.3~ 49.2 Copper 0.19 --Cobalt 0.13 --Iron Bal. Bal. . .
For convenience, the mesh fraction analyses of the higher conductivity iron and copper powder components arè also given in . Table II. In Table II, for each sieve, the U.S. Sieve Series designations and mesh openings in micrometers are given with the percent of each size powder held by that sieve, and the percent oE powder which passed through the last sieve in each analysis : indicated as -200 or -325. The absence.of an amount for a particular sieve indicates that that sieve was not used in that .
analysis. .
TABLE II
. .
l Pi ircent hel~ by Siev e :
Siev~ No.Opening ..
(U-S-) (llm)Alloy AAlloy B_IronCopper 420 1.1 __ __ __ :
250 6.4 __ O __ ;
~0 177 13.3 __ 4.0 __ -::
100 149 8.4 2 7.0 __ 140 105 14.9 17 16.0 __ :~
200 74 21.1 25 21.0 5 -:
-200 __ __ __ __ g5 230 63 __ __ 9.0 __ : .
325 44 17.4 28 18.0 __ -325 __ 17~5 28 25.0 __ Ll lZ 100% lOO.OZ 100%
The high-conductivity metals used in these examples were water atomized commerically pure iron powder and electrolytic commercially pure copper powder. The iron powder had a chemical analysis of 99.1 w/o iron, with 0.06 w/o carbon, 0.20 w/o manganese 0.05 w/o silicon, 0. 008 w/o phosphorus, 0.015 w/o sulfur, and the balance being incidental impurities. The copper powder : -contained 99.5 w/o copper, with 0.05 w/o iron, 0.03 w/o lead, ~-~ 0.01 w/o sulEur, 0.08 w/o acid insoluble impurities, and charac--` terized by a loss in hyd.rogen of 0.28 w/o (A.S.T.M. E-159). The .
7~L;Z3 sieve analyses of these powders is given in Table II, with the copper powder simply indicated as 5~ +200 mesh and the balance -200 mesh.
Example 1 was prepared as a 50/50 w/o mixture of -230 mesh copper powder and -40 mesh Alloy A powder, equivalent to about 48 volume percent copper powder. Example 2 was prepared as a 50/50 w/o mixture of +100 mesh iron powder and -40 mesh Alloy A powder, and Example 3 as a 50/50 w/o mixture of +100 mesh iron powder and -100 mesh Alloy B powder, both these exam-ples being equivalent to about 51 volume percent iron powder.
Each mixture was blended one hour in a ball mill blender and then compacted at 99 thousand pounds per square inch (ksi) in a hydraulic press to coupons 2 inches by 1-1/2 inches by about 0.20 inch thick t5-1 cm x 3.8 cm x 5.1 mm). The compacts of Examples 2 and 3 were then sintered at 2300F (1260C) while the compact of Example 1 containing the lower melting point copper was sintered at 1850F (1010C), all three being sin-tered for about 3 minutes in a hydrogen atmosphere. The sin-tered compacts were cold rolled to about 0.10 inch (2.54 mm) thick or about a 50~ reduction and resintered as before. Each was then cold rolled to OoO10 inch ~0.254 mm) thick strip, a commonly used size for lead frames, with intermediate anneals as required. In each case, annealing was carried out in a dissociated ammonia atmosphere at about 1900F (1040C) for Examples 2 and 3 and at about 1650F (900~C) for Example 1.
Specimens of Examples 1-3 were made from the 0.010 inch thick strip for thermal expansion and electrical resis-tivity tests, the measured results of which are given in Table III in the first line for each example designated "meas.". The components of each Example are indicated under each example number, Cu or Fe for the copper or iron powders, and A or B for the powders of Alloys A or B. In addition, parallel values, designated "calc.", for the expansion coefficients are given for each example calculated by taking the average of the coef-ficients of the two components adjusted according to the volume percent of each in the composite. It should be noted that the ~` -properties for iron came from the National Bureau of Standards publication "Mechanical and Physical Properties of Metals and Alloys" and those for copper from an NBS data sheet on standard -~
copper rather than from experimental measurement. ~
' . .:
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4~2~
TABLE III
Thermal Expansion Coe~ficients Electrical (10 ¦C) from 25~C to Resistivit 100C 200C 300C 400C 500~C Q= f Ex. 1 meas. 9.4 10.511.0 11.4 12.1 134 22.3 (Cu+A) calc. 10.8ll.o11.111.8 12.9 __ __ Ex. 2 meas. 7.27.9 8.3 9.2 10 3 167 27.8 (Fe+A) calc. 8.79.0 9.310.0 11.3 __ __ Ex. 3 meas. 8.79.6 10.5ll.Z 11.7 164 27 3 (Fe~B) calc. 10.511.111.411.6 12.2 __ _ Alloy A 5.25.0 5.0 5.9 7.9 40066.5 Alloy B 8.79.4 9.3 9.1 9.7 29048.2 Copper 16.9 17.4 17.818.1 18.4 10 1.7 Iron 12.2 12.8 13.413.9 14.5 60 10.0 Examples 1-3 all had the unique combination of -low expansivity and high conductivity characteristic of this invention. Example 1, prepared from copper and Alloy A powders, had a lower resistivity (higher conductivity) than Example 2 pr.epared from iron and Alloy A powders, while Example 2 had a lower expansivity than Example 1. The differences in these properties of Examples 1 and 2 reflect the lower resistivity and higher expansivity of copper compared to iron, and illustrates ~ `
how the properties of the composite strip depend on those of its component powders, and, more particularly, the effect ~ of using different high-conductivity metal powders with the same ; low-expansivity alloy powder. Example 2, prepared from iron and -40 mesh Alloy A powders had a lower expansivity and slightly higher resisitivity than Example 3 which was prepared from iron and -100 mesh Alloy B powders. In this case, different low-expansivity alloy powder components were combined with the same high-conductivity iron powder, and the differences in expansivity and resistivity of Examples 2 and 3 reflect the differences in those properties between Alloys A and B. However, although ;
Alloy B has a much lower resistivity than Alloy A, 290 ohm/cmf as compared to 400 ohm/cmf, it can be seen that the resistivity of Example 3 is only slightly lower than that of Example 2, 164 ohm/cmf as compared to 167 ohm/cmf. This is believed to be at least partly the result of the coarser particle size distribution ` of the -40 mesh Alloy A powder as compared to the -100 mesh 40 Alloy B powderr and serves to illustrate the effect of the ~ ~-particle size distributions of the component powders on the properties of the composite strip, as will be ~iscussed further hereinbelow.
: ~ :
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., . . ~ . . - ~ ",:
.
~7~Z3 Another disirable feature of the present invention shown by Examples 1-3 is that the thermal expansivities of the composite strips were unexpectedly lower than those calculated for the strips as can be seen by comparing the measured values with the calculated values in Table III. The reason for these lower measurements is not fullyunderstood, but is believed to be at least partly the result of some of the nickel in the lower expansivity alloy powder diffusing into the higher expansivity metal powder which would result in the lowering of the expansivity of both powders.
Examples 4-11 As ad~itional illustrations of the present invention and to show the effects of certain process variables on the -properties of the composite strip material, Examples 4-11 were made from mixtures of Alloy A powder and copper or iron powder as summarized in Table IV below. The component powders were the same as those previously described in connection with Examples 1-3. Each of the Examples 4-11 was a 50 w/o mixture o~ Alloy A powder with the elemental metal powder indicated in Table IV. The mesh sizes given in Table IV, either -230 (fine) or +100 (coarse), are the sizes to which the component powders for each example were sieved before mixing, having started with the particle size distributions as given in Table II. In addition, the sintering time in hours and the sintering temperature are also given for each example.
TAsLE IV
~ .
: ~ : : :
Sintering Treatment Metal Mesh , Time I Temp. Temp.
Ex. No. Component Size ~ (hrs)¦ (DF) (~C~
4 Copper+100 1 0.05 1800 9~2 .
Copper-230 1 0.05 1800 982 6 Copper+100 1 1 18751024 : ~
7 Copper-230 1 1 18751024 :-~ ~ :
I .:
8 Iron+100 0.05 20501~21 :
: 9 Iron-230 0.05 20501121 : :
Iron+100 1 21501177 :. :
11 Iron-230 1 21501177 Each mixture of powders was blended for 1/2 hour and compacted at room temperature and 132 ksi into c~lindrical 40 coupons 2 inches in diameter and 0.2 inches thick, one coupon ;~
being made ~or each example. Each coupon was then sintered in .:
. .
11 ., ,,' ,. - . . ~ :
7~Z3 a dry hydrogen atmosphere at the temperature and for the time indicated for each example in Table IV. The sintered compacts were cold rolled 30 to 50%, with the amount of reduction given each compact being determined by its edge and surface integrity during rolling. After removing the checked edges, the samples were annealed and cold rolled t~ a suitable thickness, 0.060-0.1 inch, for preparing thermal expansion specimens. These were cut to 2 inch long and 0.25 inch wide specimens and annealed for 1/2 hour at 1150~ ~or the copper/Alloy A specimens and 1600F for the iron/Alloy A specimens. The ther.~al expansion of each example was then measured on a recording dilatometer, with the average thermal expansion coefficient (10 6/oC) for each example from 25C to 400C given in Table V. The samples were again trimmed and cold rolled to a thickness suitable for electrical resistivity measurements, 0.010-0.020 inch thick. -After annealing, as above, the electrical resistivities were measured and are given in Table V in ohm/cmf. Specimens of these samples were then cold rolled to 0.013 inch thick, annealed at 1875F in NH3 and cold rolled to 0.010 inch thick for mechanical property tests. $his uniform treatment was used for both the iron and copper-containing samples, although it will be recognized that for particular compositions, trea~ments can be readily determined by well-known metallurgical procedures to optimize desired mechanical properties. Bend tests were performed in both the transverse and longitudinal directions on specimens of Examples 8 and 9, the results as shown in Table ~ being the average number of 90 bends to failure in 3 tests on each strlp.
TABLE V
Exp. Coeff.¦ Elect. ~ Bend Tests t 25-400C Resis. No. to Failure Ex. No. (lo-6/~C) Q/cmf I Tran., Long. ~
. :
~ 411.96 35 __ __ ; 511.95 120 __ __ 611.93 98 __ __ 712.64 174 __ __ 89.85 117 8 4 , 910.98 163 4.3 1.7 -~
1010.02 150 __ __ 1112.33 208 __ __ ~;
`: :
. .
. .. . . . .
In general, a better combination of low expansivity and low resistivity (high conduc~ivity) was obtained in both the copper-containing and iron-containing Examples which were formed from the coarser component powders with sintering at the lower temperatures for the shorter times. This can be seen by comparing Example 4 with Exa~ple 7 of the copper-containing strips and Example 8 with Example ll of the iron-containing strips. The factors which are tested here, coarser powders, lower sintering temperature, and shorter sintering time, are all believed to reduce the amount of alloying between the powder particles in the strip material. By minimizing the alloying between the component powders in the composite strip, a better combination of expansivity and conductivity is provided.
The bend tests results indicate that strip made from coarser powders (Example 8) is more ductile than that made from finer powders (Example 9). In addition, the strip of Example 8 also had a better ductility than one made from Alloy A alone, which had corresponding average bend test results of 6 trans-versely and 4.7 longitudinally. Similar tests done on copper/ -ALloy A samples also indicated that coarser powders produce more ductile strip. This higher ductility can be an important factor because it is often necessary to bend lead frames formed from this strip several times during the manufacture of integrated ~ -circuit components.
Tensile test specimens were prepared from the 0.010 inch thick strip samples, and ultimate tensile strength (UTS), percent elongation (% El.) in a 2-inch length and hardness (Rockwell Rb) were determined, The results are shown in Table VI, with parallel results for a sample prepared from Alloy A
alone also given for comparison.
TABLE VI
. '::
UTS Hardness Ex. No. (~si~ %E1 4 61 1.668 96 2.184 1 ;
6 79 1.868 7 102 2.384 ! ': ' 8 88 2.1~2 9 118 2.286 91 2.681 123 2.6 _ 8~ !
Alloy A 1 1_2_¦ 5.1 1 80 Higher strengths, elongations and hardness were obtained from those samples made from the finer powders (Examples 5, 7, 9 .. ' ~ :
:' ..
~; ~ :, ' ,, ,' ' . - . , : . - . ' .
, . , . . , . ., :
7~3 and ll) as compared to those made from coarser powders (Examples 4/ 6, a and lO), with the iron/ Alloy A samples (Examples 8-ll) higher than the corresponding copper/Alloy A samples (Examples 4-7). As previously discussed, all of these examples were prepared with the same finishing treatment which may not be the best treatmen-t for obtaining optimum mechanical properties for these particular samples.
The low-expansivity metal powders and high conductivity metal pcwders in the above examples each consisted of a single ~lO substantially homogeneous composition. It is also contemplated that the compacted article in accordance with the present invention can also be made from klends of powders in which the component low expansivity powders and/or the high conductivity powders are themselves blends of two or more different metal powders, which can be either elemental or pre-alloyed powders as required to provide the desired properties.
; Furthermore, compacted articles made in accordance with the present invention can also include additional material other than the low expansivity and high conductivity powders, provided that care is taken to insure that the desired expan-sivity and conductivity are obtained in the final product.
It is recognized that the method and product of the present invention will have a wide variety of uses, and it is not intended by reference to the substantially theoretical density of the compacted article to thereby restrict the scope ; of the present invention. In its preferred form, the present invention provides compacted articles having a density greater ; than 95% of theoretical and densities of about 99~ or better are ~
readily attained. It is also contemplated that, when desired, -compacted articles of lower density can also be provided.
The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.
.~ ' . .
.
- -:
Claims (26)
1. A compacted article comprising 15-85 volume percent of compacted particles of a first metal powder having an average thermal expansion coefficient over the range of 25°C to 400°C of less than about 12 x 10-6/°C, and the balance compacted particles of a second metal powder having an electrical resistivity of less than 200 ohm/cmf, said compacted particles of both powders being substantially intermixed throughout said article, with said second metal powder having a corresponding 400°C thermal expansion coefficient greater than that of said first metal powder, said first metal powder having an electrical resistivity greater than that of said second metal powder, and the extent of alloying between the particles of said first and second metal powders being so small that said article has a 400°C thermal expansion coefficient less than that of said second metal powder and an electrical resistivity less than that of said first metal powder.
2. The compacted article of claim 1 comprising about 40-60 volume percent of the compacted particles of said first metal powder.
3. The compacted article of claim 1 in which said first metal powder comprises by weight about 20 to 55% nickel, up to about 25% cobalt, up to about 5% chromium, and the balance iron, the iron content being about 45 to 70%; and in which said second metal powder is selected from the group consisting in weight percent of (a) elemental iron comprising up to about 10%
chromium, up to about 10% nickel, up to about 5% copper, and the balance at least about 90% iron, (b) elemental copper comprising up to about 20% nickel, up to about 20% zinc, up to about 10% aluminum, 3% of iron or beryllium, and the balance at least about 80% copper, and (c) elemental nickel comprising up to about 20% copper, up to about 20% iron, and the balance at least about 80% nickel.
chromium, up to about 10% nickel, up to about 5% copper, and the balance at least about 90% iron, (b) elemental copper comprising up to about 20% nickel, up to about 20% zinc, up to about 10% aluminum, 3% of iron or beryllium, and the balance at least about 80% copper, and (c) elemental nickel comprising up to about 20% copper, up to about 20% iron, and the balance at least about 80% nickel.
4. The compacted article of claim 3 wherein said first metal powder has a 400°C thermal expansion coefficient of less than about 10 x 10-6/°C and said second metal powder has an electrical resistivity of less than 100 ohm/cmf.
5. The compacted article of claim 4 wherein said first metal powder contains about 35 to 52% nickel.
6. The compacted article of claim 4 wherein said second metal powder is elemental iron containing at least 99%
iron.
iron.
7. The compacted article of claim 4 wherein said second metal powder is elemental copper containing at least 99%
copper.
copper.
8. The compacted article of claim 4 wherein said second metal powder is elemental nickel containing at least 99%
nickel.
nickel.
9. The compacted article of claim 4 wherein the composition is balanced to provide a compacted article with a 400°C thermal expansion coefficient of less than about 12 x 10-6/°C and an electrical resistivity of less than about 200 ohm/cmf.
10. The compacted article of claim 9 wherein the composition is balanced to provide a compacted article with a 400°C thermal expansion coefficient of less than about 10 x 10-6/°C.
11. The compacted article of claim 9 wherein the composition is balanced to provide a compacted article with an electrical resistivity of less than about 150 ohm/cmf.
12. The compacted article of claim 11 wherein the composition is balanced to provide a compacted article with an electrical resistivity of less than about 150 ohm/cmf.
13. In a method for making a compacted article, the steps of making a mixture of about 15-85 volume percent of a first metal powder having an average thermal expansion coefficient over the range of 25°C to 400°C of less than about 12 x 10-6/°C
with the balance a second metal powder having an electrical resistivity of less than 200 ohm/cmf, said second metal powder having a corresponding 400°C thermal expansion coefficient greater than that of said first metal powder, and said first metal powder having an electrical resistivity greater than that of said second metal powder; and forming said mixture into a compacted article while controlling the amount of alloying between the particles of said first and second metal powders so that the compacted article has a 400°C thermal expansion coefficient less than that of said second metal powder and an electrical resistivity less than that of said first metal powder.
with the balance a second metal powder having an electrical resistivity of less than 200 ohm/cmf, said second metal powder having a corresponding 400°C thermal expansion coefficient greater than that of said first metal powder, and said first metal powder having an electrical resistivity greater than that of said second metal powder; and forming said mixture into a compacted article while controlling the amount of alloying between the particles of said first and second metal powders so that the compacted article has a 400°C thermal expansion coefficient less than that of said second metal powder and an electrical resistivity less than that of said first metal powder.
14. The method of claim 13 wherein said mixture is made of about 40-60 volume percent of said first metal powder.
15. The method of claim 13 in which said first metal powder comprises by weight about 20 to 55% nickel, up to about 25% cobalt, up to about 5% chromium, and the balance iron, the iron content being about 45 to 70%; and in which said second metal powder is selected from the group consisting in weight percent of (a) elemental iron comprising up to about 10% chromium, up to about 10% nickel, up to about 5% copper, and the balance at least about 90% iron, (b) elemental copper comprising up to about 20% nickel, up to about 20% zinc, up to about 10% aluminum, up to about 3% of iron or beryllium, and the balance at least about 80% copper, and (c) elemental nickel comprising up to about 20% copper, up to about 20% iron, and the balance at least about 80% nickel.
16. The method of claim 15 wherein forming said mixture includes applying pressure thereto to form a green preform, and densifying said preform to form the compacted article.
17. The method of claim 15 wherein forming said mixture includes applying pressure thereto to form a green preform, and densifying said preform by sintering at a temperature at least about 100°F below the lower of the melting points of the two metal powders to form the compacted article.
18. The method of claim 17 wherein said preform after being densified is cold rolled into strip, and then annealed at a temperature below that of said sintering temperature.
19. The method of claim 15 wherein said first metal powder has a 400°C thermal expansion coefficient of less than about 10 x 10-6/°C and said second metal powder has an electrical resistivity of less than 100 ohm/cmf, and wherein the composition of the compacted article is balanced to provide a compacted article with a 400°C thermal expansion coefficient of less than about 12 x 10-6/°C and an electrical resistivity of less than about 200 ohm/cmf.
20. The method of claim 19 wherein said first metal powder contains about 35 to 52% nickel.
21. The method of claim 19 wherein said second metal powder is elemental iron containing at least 99% iron.
22. The method of claim 19 wherein said second metal powder is elemental copper containing at least 99% copper.
23. The method of claim 19 wherein said second metal powder is elemental nickel containing at least 99% nickel.
24. The method of claim 19 wherein the composition is balanced to provide a compacted article with a 400°C thermal expansion coefficient of less than about 10 x 10-6/°C.
25. The method of claim 19 wherein the composition is balanced to provide a compacted article with an electrical resis-tivity of less than about 150 ohm/cmf.
26. The method of claim 24 wherein the composition is balanced to provide a compacted article with an electrical resis-tivity of less than about 150 ohm/cmf.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US805,040 | 1977-06-09 | ||
| US05/805,040 US4158719A (en) | 1977-06-09 | 1977-06-09 | Low expansion low resistivity composite powder metallurgy member and method of making the same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1087423A true CA1087423A (en) | 1980-10-14 |
Family
ID=25190544
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA304,871A Expired CA1087423A (en) | 1977-06-09 | 1978-06-06 | Low expansion low resistivity composite powder metallurgy member |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4158719A (en) |
| JP (1) | JPS544210A (en) |
| CA (1) | CA1087423A (en) |
| DE (1) | DE2825262A1 (en) |
| FR (1) | FR2393640A1 (en) |
| GB (1) | GB1588208A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4836979A (en) * | 1988-06-14 | 1989-06-06 | Inco Limited | Manufacture of composite structures |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3065931D1 (en) * | 1980-03-03 | 1984-01-26 | Bbc Brown Boveri & Cie | Process for making a memory alloy |
| JPS5921032A (en) * | 1982-07-26 | 1984-02-02 | Sumitomo Electric Ind Ltd | Substrate for semiconductor device |
| US4752334A (en) * | 1983-12-13 | 1988-06-21 | Scm Metal Products Inc. | Dispersion strengthened metal composites |
| US4799955A (en) * | 1987-10-06 | 1989-01-24 | Elkem Metals Company | Soft composite metal powder and method to produce same |
| US5015533A (en) * | 1988-03-10 | 1991-05-14 | Texas Instruments Incorporated | Member of a refractory metal material of selected shape and method of making |
| US4894293A (en) * | 1988-03-10 | 1990-01-16 | Texas Instruments Incorporated | Circuit system, a composite metal material for use therein, and a method for making the material |
| US4885214A (en) * | 1988-03-10 | 1989-12-05 | Texas Instruments Incorporated | Composite material and methods for making |
| US4956012A (en) * | 1988-10-03 | 1990-09-11 | Newcomer Products, Inc. | Dispersion alloyed hard metal composites |
| US5039335A (en) * | 1988-10-21 | 1991-08-13 | Texas Instruments Incorporated | Composite material for a circuit system and method of making |
| US5526867A (en) * | 1988-11-10 | 1996-06-18 | Lanxide Technology Company, Lp | Methods of forming electronic packages |
| US4994903A (en) * | 1989-12-18 | 1991-02-19 | Texas Instruments Incorporated | Circuit substrate and circuit using the substrate |
| US5049184A (en) * | 1990-12-17 | 1991-09-17 | Carpenter Technology Corporation | Method of making a low thermal expansion, high thermal conductivity, composite powder metallurgy member and a member made thereby |
| US5292478A (en) * | 1991-06-24 | 1994-03-08 | Ametek, Specialty Metal Products Division | Copper-molybdenum composite strip |
| US5820721A (en) * | 1991-07-17 | 1998-10-13 | Beane; Alan F. | Manufacturing particles and articles having engineered properties |
| US5453293A (en) * | 1991-07-17 | 1995-09-26 | Beane; Alan F. | Methods of manufacturing coated particles having desired values of intrinsic properties and methods of applying the coated particles to objects |
| US5156923A (en) * | 1992-01-06 | 1992-10-20 | Texas Instruments Incorporated | Heat-transferring circuit substrate with limited thermal expansion and method for making |
| DE4217531C1 (en) * | 1992-05-27 | 1993-12-16 | Wieland Werke Ag | Process for the production of slip-cast isotropic composite materials based on copper with a low coefficient of thermal expansion and high electrical conductivity and their use |
| US5310520A (en) * | 1993-01-29 | 1994-05-10 | Texas Instruments Incorporated | Circuit system, a composite material for use therein, and a method of making the material |
| US5413751A (en) * | 1993-04-14 | 1995-05-09 | Frank J. Polese | Method for making heat-dissipating elements for micro-electronic devices |
| US5654587A (en) * | 1993-07-15 | 1997-08-05 | Lsi Logic Corporation | Stackable heatsink structure for semiconductor devices |
| US5423899A (en) * | 1993-07-16 | 1995-06-13 | Newcomer Products, Inc. | Dispersion alloyed hard metal composites and method for producing same |
| US5514327A (en) * | 1993-12-14 | 1996-05-07 | Lsi Logic Corporation | Powder metal heat sink for integrated circuit devices |
| US5693981A (en) * | 1993-12-14 | 1997-12-02 | Lsi Logic Corporation | Electronic system with heat dissipating apparatus and method of dissipating heat in an electronic system |
| US5814536A (en) * | 1995-12-27 | 1998-09-29 | Lsi Logic Corporation | Method of manufacturing powdered metal heat sinks having increased surface area |
| US5686676A (en) * | 1996-05-07 | 1997-11-11 | Brush Wellman Inc. | Process for making improved copper/tungsten composites |
| DE19729677B4 (en) * | 1997-07-11 | 2006-05-18 | Curamik Electronics Gmbh | Housing for semiconductor devices, in particular for power semiconductor components |
| US6509590B1 (en) | 1998-07-20 | 2003-01-21 | Micron Technology, Inc. | Aluminum-beryllium alloys for air bridges |
| FR2784691B1 (en) * | 1998-10-16 | 2000-12-29 | Eurotungstene Poudres | MICRONIC PREALLY METALLIC POWDER BASED ON 3D TRANSITIONAL METALS |
| JP3479738B2 (en) * | 1998-11-16 | 2003-12-15 | 株式会社アライドマテリアル | Semiconductor package and method of manufacturing heat dissipation substrate used therein |
| US7211512B1 (en) | 2000-01-18 | 2007-05-01 | Micron Technology, Inc. | Selective electroless-plated copper metallization |
| US6420262B1 (en) | 2000-01-18 | 2002-07-16 | Micron Technology, Inc. | Structures and methods to enhance copper metallization |
| US7262130B1 (en) | 2000-01-18 | 2007-08-28 | Micron Technology, Inc. | Methods for making integrated-circuit wiring from copper, silver, gold, and other metals |
| US6674167B1 (en) * | 2000-05-31 | 2004-01-06 | Micron Technology, Inc. | Multilevel copper interconnect with double passivation |
| US6423629B1 (en) * | 2000-05-31 | 2002-07-23 | Kie Y. Ahn | Multilevel copper interconnects with low-k dielectrics and air gaps |
| KR100594602B1 (en) * | 2003-04-28 | 2006-06-30 | 히다치 훈마츠 야킨 가부시키가이샤 | Method for producing copper based material of low thermal expansion and high thermal conductivity |
| US20080165442A1 (en) * | 2006-11-08 | 2008-07-10 | Wenshan Cai | System, method and apparatus for cloaking |
| JP6334325B2 (en) * | 2014-08-29 | 2018-05-30 | 日本冶金工業株式会社 | Low thermal expansion alloy for bimetal |
| US11130201B2 (en) * | 2014-09-05 | 2021-09-28 | Ametek, Inc. | Nickel-chromium alloy and method of making the same |
| CN113322397B (en) * | 2021-05-27 | 2022-04-12 | 宁波金田铜业(集团)股份有限公司 | Preparation method of powder metallurgy copper-iron alloy strip with excellent bending performance |
| CN116666229A (en) * | 2023-08-02 | 2023-08-29 | 西安畅榜电子科技有限公司 | Chip frame and processing method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1136174A (en) * | 1954-11-30 | 1957-05-10 | Birmingham Small Arms Co Ltd | Manufacture of metal powder agglomerates |
| US3120436A (en) * | 1961-03-23 | 1964-02-04 | Presmet Corp | Powdered metal article and method of making |
| US3652261A (en) * | 1969-06-25 | 1972-03-28 | American Metal Climax Inc | Iron powder infiltrant |
| US3685134A (en) * | 1970-05-15 | 1972-08-22 | Mallory & Co Inc P R | Method of making electrical contact materials |
| DE2142708C3 (en) * | 1971-08-26 | 1978-11-09 | Robert Bosch Gmbh, 7000 Stuttgart | Process for the aftertreatment of sintered bodies made of iron, copper and tin |
| DE2346179A1 (en) * | 1973-09-13 | 1975-06-26 | Siemens Ag | COMPOSITE METAL AS CONTACT MATERIAL FOR VACUUM SWITCHES |
| JPS51146318A (en) * | 1975-06-11 | 1976-12-15 | Teikoku Piston Ring Co Ltd | Sintered alloy with heat and wear resistance |
-
1977
- 1977-06-09 US US05/805,040 patent/US4158719A/en not_active Expired - Lifetime
-
1978
- 1978-05-31 GB GB24734/78A patent/GB1588208A/en not_active Expired
- 1978-06-06 CA CA304,871A patent/CA1087423A/en not_active Expired
- 1978-06-08 DE DE19782825262 patent/DE2825262A1/en not_active Ceased
- 1978-06-08 JP JP6838278A patent/JPS544210A/en active Granted
- 1978-06-09 FR FR787817382A patent/FR2393640A1/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4836979A (en) * | 1988-06-14 | 1989-06-06 | Inco Limited | Manufacture of composite structures |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2393640A1 (en) | 1979-01-05 |
| DE2825262A1 (en) | 1978-12-21 |
| JPS544210A (en) | 1979-01-12 |
| JPS5634602B2 (en) | 1981-08-11 |
| FR2393640B1 (en) | 1982-08-06 |
| GB1588208A (en) | 1981-04-15 |
| US4158719A (en) | 1979-06-19 |
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