|Publication number||US3766634 A|
|Publication date||Oct 23, 1973|
|Filing date||Apr 20, 1972|
|Priority date||Apr 20, 1972|
|Also published as||DE2319854A1, DE2319854C2|
|Publication number||US 3766634 A, US 3766634A, US-A-3766634, US3766634 A, US3766634A|
|Inventors||Babcock G, Bryant W, Burgess J, Neugebauer C|
|Original Assignee||Gen Electric|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (12), Referenced by (113), Classifications (16)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent [1 1 Babcock et a1.
[ METHOD OF DIRECT BONDING METALS TO NON-METALLIC SUBSTRATES  Inventors: Guy L. Babcock, North Syracuse;
Walter M. Bryant, Liverpool; Constantine A. Neugebauer; James F. Burgess, both of Schenectady, all of N.Y.
 Assignee: General Electric Company,
 Filed: Apr. 20, 1972  Appl. No.: 245,889
 US. Cl. 29/4719, 29/4729, 29/473.l
[4 1 Oct. 23, 1973 3,676,292 7/1972 Pryor et al. 287/l89.365 X 3,717,926 2/1973 Anikin et al. 29/4729 X FOREIGN PATENTS OR APPLICATIONS 761,045 11/1956 Great Britain 29/4729 784,931 10/1957 Great Britain 29/4789 Primary Examiner-Robert D. Baldwin Assistant ExaminerRonald .1. Shore Att0rney-John F. Ahern et a1.
 ABSTRACT A method is described for direct bonding of metallic members to non-metallic members at elevated temperatures in a controlled reactive atmosphere without resorting to the use of electroless plating, vacuum deposition or intermediate metals. The method comprises placing a metal member such as copper, for example, in contact with a non-metallic substrate, such as alumina, heating the metal member and the substrate to a temperature slightly below the melting of the metal, e.g., between approximately 1,065C. and 1,080C. for copper, the heating being performed in a reactive atmosphere, such as an oxidizing atmosphere, for a sufficient time to create a copper-copper oxide eutectic melt which, upon cooling, bonds the copper to the substrate. Various metals, nonmetals and reactive gases are described for direct bonding.
20 Claims, 7 Drawing Figures d PLACE METAL MEMBER OVER SUBSTRA TE HEAT IN b REA 6 77 W5 A TMOSPHEAE To FORM 50756714 MEL 7 c sarscr/c" MEL 7 Wm ME TAL A N0 .508: new re PATENIEU 00123 1975 sum 1 or 2 PLAE Ms TAL MEMBER OVER .S'UBSTRA 75 HEA T /N REA C 77 [/5 A TMOSPHERE TO FORM EUTECT/C MEL 7 60756776 MEL 7 war: M5 m1. A #0 sues m4 r5 C004 com os/ TE WITH METAL 130N050 7o SUBSTRAT '1 METHOD OF DIRECT BONDING METALS TO NON-METALLIC SUBSTRATES The present invention relates to improved bonds and methods of bonding together non-metallic members to metal members and non-metallic members to other non-metallic'members. This application relates to concurrently filed application Ser. No. 245,890 of common assignee, the entire disclosure of which is incorporated herein by reference thereto.
Various methods of bonding non-metallic members together or to metallic members have been employed in an attempt to satisfactorily wet both members. One such method includes a mixture of titanium hydride and a solder metal, such as copper, silver or gold, applied to the member to be metallized or bondedand the hydride is disassociated by the application of heat in the presence of the solder'metal. In this process, the heating is preferably done in a non-oxidizing atmosphere, such as pure dry hydrogen. The description found in US. Pat. No. 2,570,248 is typical of such a process.
Another method of bonding metals to ceramics is described by J .T. Klomp of Philips Research Laboratories. This method-is described as employing low-oxygen affinity metals applied to a ceramic under high pressures, e.g., l Kg/cm Where oxygen-affinity metals are employed, sufficiently high pressures are required to destroy the oxide film so that metal-ceramic contact can be made." Hence, this method employs extremely high pressures to effect bonding. While these methods may produce desirable bonds for many applications, obviously the most desirable bond would be a direct bond between the copper and the ceramic substrate which did not require high pressures.
Another process for forming metallic bonds is described in U.S..Pat. No. 2,857,663 by James E. Beggs. Basically, this method employs an alloying metal, such as a metal from the titanium group, IVb, of the Periodic Table, and an alloying metal, such as copper, nickel, molybdenum, platinum, cobalt, chromium or iron. When the alloying metal and a member of the titanium group are placed-between non-metallic refractory materials or a non-refractory'metallic material'and a metallic material and are heated to a temperature at which a eutectic liquidus is formed, a strong bond forms between the adjacent members. While this process has been satisfactory for many applications, the desire to improve the integrity of the bond, increase the thermal conductivity between a metal member and a nonmetallic refractory member as well as providing a high current carrying conductor on the non-metallic refractory member has prompted researchers to seek still other methods of bonding.
It is therefore an object of this invention to provide a bond and a method of bonding non-metallic materials together, and metal members to non-metallic members without the use of intermediary bonding layers.
Another object of this invention is to provide a bond and a method of bonding non-metallic refractory materials together or to metal members in a simple heating step without the need for intermediate wetting agents.
Yet another object of this invention is to provide a tenacious bond and a method of forming this bond between a non-metallic refractory material and a metal which is useful in the formation of integrated circuit modules, and to provide high current carrying electrical conductors on insulating members with high thermal conductivity paths to a heat sink and to provide hermetic seals between two non-metallic refractory materials.
It is also an object of this invention to provide a bond for joining together a metallic and a non-metallic member, which bond forms at a temperature below the melting point of the metal, but at a temperature which produces a eutectic with the metal.
Briefly, our invention relates to bonds and methods of bonding together non-metallic members to metallic members. By way of example, a bond between metallic and non-metallic members is formed by placing a metallic member in contact with a non-metallic member preferably exhibiting refractory characteristics and elevating the temperatures of the members in a reactive atmosphere of selected gases and at controlled partial pressures for a sufficient time to produce a eutectic composition which exhibits a eutectic melt. This eutectic melt forms at a temperature below the melting point of the metallic member and wets the metallic member and the non-metallic refractory member so that upon cooling, a tenacious bond is formed between the metallic and non-metallic members. Useful metallic materials include copper, nickel, cobalt and iron, for example. Useful reactive gases include oxygen, phosphorusbearing compounds and sulfur-bearing compounds, for example. In general, the amount of reactive gas necessary to produce tenacious bonds is dependent, in part, upon the thickness of the metallic and non-metallic members and the times and temperatures required to form the eutectic melt.
Other objects and advantages of our invention will become more apparent to those skilled in the art from the following detailed description taken in connection with the accompanying drawings in which:
FIG. 1 illustrates a typical bond between nonmetallic and metallic materials in accord with our invention;
FIG. 2 is a series of schematic illustrations in the process of making a metal to non-metal bond in accord with one embodiment of our invention;
FIG. 3 is a flow diagram illustrating the process steps in accord with the embodiment of FIG. 2;
FIGS. 4 and 5 illustrate still other bonds made in accord with our invention;
FIG. 6 schematically illustrates a horizontal furnace useful in practising our invention; and
FIG. 7 schematically illustrates a vertical furnace useful in practising our invention.
FIG. 1 illustrates, by way of example, a typical bond 11 between a non-metallic refractory member 12 and a metallic member 13. The bond 11 comprises a eutectic composition formed with the metallic member and a reactive gas in accord with the novel aspects of our invention.
As used herein, the term non-metallic material is intended to include refractory materials such as alumina (A1 0 beryllia (BeO), fused silica or other useful materials, such as titanates and spinnels, for example. Alumina and beryllia are particularly useful in the practice of our invention since they exhibit a high thermal conductivity which makes them particularly useful for semi-conductor integrated circuit applications or in high power electrical circuits. However, other nonmetallic refractory materials may also be employed, if
desired, and our invention is not limited solely to these materials.
The metallic member 13 may include such materials as copper, iron, nickel, cobalt, chromium and silver, for example. Also, alloys of these materials, such as copper-nickel, nickel-cobalt, copper-chromium, coppercobalt, iron-nickel, silver-gold, and ternary compositions of iron, nickel and cobalt, are useful in practising our invention. As will become more apparent from the following description, still other metallic materials, such as beryllium-copper, for example, may also be advantageoujsly employed, if desired. A
The novel process for making a tenacious bond between the metallic member 13 and a substrate 12 such as a non-metallic refractory material 12 is illustrated schematically in FIG. 2 and in the flow chart of FIG. 3. More specifically, FIG. 2 illustrates a non-metallic refractory material 12, such as alumina or beryllia, for example, with a metallic member 13 overlying the nonmetallic refractory substrate 12. The substrate 12 and the metallic member 13 are placed in a suitable oven or furnace including a reactive atmosphere which at an elevated temperature forms a eutectic composition 11 on the surfaces of the metallic member 13. The term eutectic or eutectic composition means a mixture of atoms of the metallic member and the reactive gas or compound formed between the metal and the reactive gas. For example, where the metallic member is copper and the reactive gas is oxygen, the eutectic is a mixture of copper and copper oxide. Where the metal is nickel and the reactive gas is phosphorus, the eutectic is a mixture of nickel and nickel phosphide. Still further, where the metallic member is cobalt and the reactive gas is a sulfur-bearing gas,"the eutectic is formed between cobalt and cobalt sulfide.
Table I is'a representative listing of still other eutectics which are useful in practising our invention. These eutectics are formed by reacting the metallic member to be bonded with a reactive gas c'ontrollably introduced into the'oven or furnace.
TABLE I Per'Cent by Weight Metal-Gas Eutectic of Reactive Gas Eutectic Temp. C. at Eutectic Temperature Iron-oxygen 1532 0.'l6 O Copper-oxygen *1065 0.39 O, Chromium-oxygen 1800 0.6 Q; Chromium-sulfur l550 2:2 S Copper-phosphorus 7l4 I 8.4 P Nickel-oxygen l438 0.24 O, Nickel-phosphorus 880 ll.0 P Molybdenum-silicon 2070 5.5 Si Silver-sulfur 906 1.8 S Silver-phosphorus 878 1 1.0 P I Copper-sulfur l067 i 0.77 S Cobalt-oxygen 1451' i 0.23 O, Aluminum-silicon 577 11.7 Si
come tenaciously bonded together. Where alloys are employed as the metallic member, the eutectic composition is believed to form with one of the elemental metals, generally the one with the lower melting point.
One factor which appears to affect the tenacity and uniformity of the bond is the relationship between the melting point of the metallic member and the eutectic approximately 30 to 50C. of the melting point of the metallic member, for example, the metallic member tends to plastically conform to the shape of the substrate member and thereby produce better bonds than those eutectics which become liquidus at temperatures greater than approximately 50C. below the melting point of the metallic member. The uniformity of the bond therefore appears to be related to the creep of the metal which becomes considerable only near the melting point. From Table I, for example, it can be seen that the following eutectic compounds meet this requirement: copper-copper oxide, nickel-nickel oxide, cobalt-cobalt oxide, iron-iron oxide and copper-copper sulfide.
FIG. 4 illustrates an alternative embodiment of our invention wherein a non-metallic refractory material 12 has two metallic members 13 bonded to opposite surfaces thereof by bonds 1].
FIG. 5 illustrates still another embodiment of our invention wherein two non-metallic members 12, such as alumina or beryllia, for example, are bonded together by a metallic member 15. In this embodiment of our invention the eutectic forms in substantially the same manner as described above but for the fact that bonding occurs on both surfaces of the metallic member 15.
This embodiment of our invention is particularly useful in forming hermetic seals between non-metallic refractory materials, for example, such as those employed in the fabrication of vacuum tubes, such as high frequency type tubes.
Having thus described some useful embodiments of our invention and the overall method of forming metalto-non-metal and non-metal-to-non-metal bonds, apparatus useful in practising our invention along with more specific details of the process will now be described with reference to FIG. 6. More specifically, FIG. 6 illustrates a horizontal furnace comprising an elongated quartz tube 22,,for example, having a gas i nlet 23 at one end thereof and a gas'outlet 24 at the other end. The quartz tube 22 also includes an opening or port 25 through which materials are placed into and removed from the furnace. The materials are placed on a holder 26 having a push rod-27 extending through one end of the furnace so that the holder and materials placed thereon may be introduced and removed from the furnace.
i The furnace 21 is also provided with suitable heating elements, illustrated in FIG. 6 as electrical wires 28 which surround the quartz tube 22 in the region to be heated. The electrical wires 28 may, for example, be
.connected to a suitable current source, such as a 220- ,volt alternating current source. The electrical wires 28 I may then be surrounded by suitable insulating material 29 to confine the heat generated by the electrical wires to the region within the quartz tube. Obviously, those skilled in the art can readily appreciate that other heating means may also be employed, if desired, and that FIG. 6 is merely illustrative of one such heating means. The temperatureof the furnace is detected by a suitable thermocouple 29 which extends through an opening in the quartz tube so that electrical connections can bemade thereto.
FIG. 6 also illustrates a substrate 12 such as a nonmetallic refractory material positioned on the holder 26 and a metallic material 13 overlying the substrate 12. These materials are introduced into the quartz tube through the opening 25 which is then sealed by suitable stopper means.
The quartz tube 22 is then purged with a reactive gas flow of approximately 4 cubic feet per hour, for example. As used herein reactive gas flow or atmosphere means a mixture of an inert gas such as argon, helium or nitrogen, for example, with a controlled minor amount of a reactive gas, such as oxygen, a phosphorus-containing gas such as phosphine, for example, or a sulfur-containing gas such as hydrogen sulfide, for example. The amount of reactive gas in the total gas flow is dependent, in part, on the materials to be bonded and the thickness of the materials, in a manner more fully described below. In general, however, the partial pressure of the reactive gas must exceed the equilibrium partial pressure of the reactive gas in the metal at or above the eutectic temperature. For example, when bonding copper members to refractory members in a reactive atmosphere including oxygen, the partial pressure of oxygen must be above 1.5 X atmosphere at the eutectic temperature of 1,065C.
After purging the quartz tube, the furnace is then brought to a temperature sufficient to form a eutectic liquidus or melt at the metal-substrate interface. For example, for a copper-alumina bond with oxygen as the reactive gas, the temperature of the furnace is brought to between approximately 1,065C. and 1,075C. Within this range of temperatures, a copper-copper oxide eutectic forms on the copper member 13. This eutectic melt then wets the copper and the alumina to form a tenacious bond therebetween.
In general, the times necessary to form this eutectic melt range between approximately 10 minutes for 1- mil-thick copper members and approximately 60 minutes for ZSO-mil-thick copper members. A more detailed relationship between copper thickness and time at an elevated temperature of between 1,065 and l,075C. is presented below in Table II for a reactive atmosphere including oxygen.
TABLE II Copper Substrate Time at elevated Thickness, Thickness, temperature,
mils I mils minutes 1 25 Mil, 96% 10 Alumina 2 25 Mil, 96%
Alumina 5 25 Mil, 99% 15 Alumina 5 r 25 Mil, 99% 15 Beryllia I0 25 Mil, 96% 30 Alumina Mil, 96% 45 Alumina 5 150 Mil, 99%
Alumina 250 25 Mil, 96% 60 Alumina Table ll illustrates the relationship between copper thickness, non-metallic refractory material thickness and firing time in the furnace, i.e., the time at which the metal-non-metal materials remain in the furnace. From this table it is readily apparent that the firing time increases with the metal thickness, although there does not appear to be a linear relationship between the two.
By way of further example, the formation of metallic bonds-to non-metallic refractory materials in accord with our invention may also be achieved by employing a vertical-type furnace, such as that illustrated in FIG. 7. More specifically, FIG. 7 illustrates a vertical furnace 31 including a vertically positioned quartz tube 32, for example, with a carbon susceptor 33 positioned on a fused silica pedestal 34. The quartz tube 32 is sur rounded with RF. heating coils 35 which are powered by an external R.F. generator, not shown.
FIG. 7 also illustrates a substrate 36 such as a nonmetallic refractory material resting on the susceptor 33 with a metal member 37 placed thereover. inert and oxidizing gases are introduced through inlets 38 and 39, respectively. The combined gas flows pass through conduit 40 onto the metallic and non-metallic members and exhaust through an exhaust outlet 41. Flow meters 42 and 43 on each inlet monitor and control the rate of flow of the gases into the furnace.
By way of example, the operation of the vertical furnace will be described with reference to the formation of a bond between a S-mil-thick copper member and an approximately -mil-thick beryllia member. The flow meters 42 and 43 are adjusted so that pure argon is introduced at inlet 38 and argon containing 2 per cent oxygen is introduced at inlet 39. The quartz tube is then flushed or purged for approximately 10 minutes with a flow rate of approximately 2 cubic feet per hour of argon and approximately 1 cubic foot per hour of the argon-containing oxygen gas produces a total oxygen content in the combined gases of approximately 0.04 molar per cent.
During the purging time, the temperature of the susceptor, beryllia and copper members is maintained at room temperature. After the purging period, the RF. power is applied until the temperature of the copper member exceeds 1,065C., but is below l,083C. Typically, 2 to 5 minutes are required to produce this temperature which may, for example, be monitored optically. Optical monitoring of temperature is well known in the art and as the copper member heats up from room temperature, a red-brown oxidation color typical of copper oxide appears on the surface. Above 600C., the copper surface emits light strongly. At a temperature of 1,065C., a liquid layer is observed around the copper member. The liquid layer wets both the beryllia and copper members as evidenced by a drastic color change. Wetting first occurs at the outer edges of the copper member where a black color appears which then moves toward the center of the copper, until the entire copper member appears black to the eye. Under these conditions, the copper member retains its structural integrity and does not break up into separate liquid droplets. When the wetting process is completed over the entire surface area, the R.F. power is removed and the members permitted to cool. Upon removal of the copper and beryllia from the furnace, the copper is strongly bonded to the beryllia and bond strengths in excess of 20,000 pounds per square inch have been observed.
The shape of the bonded copper member is substantially the same as that of the original unbonded copper. However, there is some evidence of oxidation and precipitation of copper oxide in the bonded member. Also, some recrystallization of the grain structure within the copper member is discernible.
Without limiting our invention to any particular theory of operation, it is believed that the tenacious bonds formed in accord with our invention result from the reaction of the metal with the reacting gas during the heating period prior to the formation of the eutectic melt. During this period, a small amount of the reacting gas dissolves into the metal, but most of it reacts with the metal to form a eutectic with the metal over its exposed surfaces. At'the eutectic temperature, 1,065C. for copper-oxide, for example, a liquid phase of or near the eutectic composition forms a skin around the metal. The thickness of this molten skin depends upon the partial pressure of the reacting gas and the length of time at the elevated temperature. For example, for copper-oxygen systems, a partial pressure of oxygen less than 1.5 X 10 atmosphere (the equilibrium partial pressure 'over Cu O at 1,065C.), the copper-oxygen eutectic will not form. Hence, partial pressures in excess of this value are required to produce the desired eutectic.
Under conditions permitting the formation of the eutectic, the eutectic appears to wet the metal and the non' metallic refractory material in such a way that upon cooling, a strong bond forms between the two materials.A strong bond has also been observed between pure copper at its melting point of 1,08'3C., in theabsence of a reacting gas (or even in a reducing atmosphere), however,the copper member loses its structural integrity and forms liquid droplets which are bonded to the non-metallic refractory material.
if the partial pressure of the reacting gas is too high, all the metal reacts with the reactive gas and forms, for example, an oxide, sulfide, phosphide, etc;, which prevents the formation of the eutectic melt. Thus, an intermediate reacting gas partial pressure is required so that both the eutectic melt phase and the metallic phase are present simultaneously. Tests have illustrated that extremely strong bonds are achieved when both phases are present. Accordingly, in practising our invention the partial pressure of the reacting gas must be sufficiently great to permitthe formation of a eutectic with the metal butnot so great as to completely convert the metal to the oxide, sulfide, phosphide, etc. during the bonding time.
More specifically, we have found that consistently good bonds are achieved between metals and nonmetallic materials, such as copper and alumina or beryllia, for example, in the presence of oxygen, so long as the percentage of oxygen in the inert gas ranges between approximately 0.03 and 0.1 per cent by volume. No bonding occurred where the percentage of oxygen was less than approximately 0.01 per cent by volume because there was insufficient oxide formation. Also, no bonding occurred where the percentage of oxygen was above 0.5 per cent of the total gas flow because of complete oxidation of the metal. In the intermediate regions, i.e.', 0.01 to 0.03 and 0.1 to 0.5, marginal bonding occurs. Accordingly, to produce consistently good bonds between copper and alumina or beryllia, operation is preferable within the range of approximately 0.03 and 0.1 per cent by volume.
Table III illustrates ranges for partial pressures of the reactive gases at which good bonding occurs for other metals and gases. Only those eutectics which exhibit a eutectic temperature within 50C. of the melting point of the metal are listed.
TABLE III Eutectic Reactive Gas Compound by volume Cu-CuO 0.0l-0.5 Cu-CuS 0.0l-0.5 Ni-NiO 0.01-0.15 Co-CoO 0.0l-0.4 Fe-FeO 0.01-0.23
It is to be understood that these selected metals, nonmetals and reactive gases are given merely by way of illustration and not limitation. Further examples of suitable materials and reactive gases will occur to those skilled in the art.
For example, useful bonds are formed with the aforementioned binary metallic composition such as coppernickel, nickel-cobalt, copper-chromium, coppercobalt, iron-nickel and beryllium-copper in a reactive atmosphere including oxygen. Ternary compositions of iron, nickel and cobalt also form useful bonds in a reactive atmosphere of oxygen. Also, silver-gold compositions bond to non-metallic refractory members in a reactive atmosphere including a sulfur-bearing gas such as hydrogen sulfide, for example.
Those skilled in the art can also readily appreciate that metallic members bonded to a non-metallic refractory material may be patterned by photolithographic masking and etching techniques to produce a desired pattern in the metallic member after forming the desired bond. This method of forming patterned conductors is preferable in the fabrication of semiconductor integrated circuits, for example, where the size of the conductor if preformed before bonding would pose serious handling problems. I
Microwave tests performed on electrical circuits formed by patterning copper bonded to alumina exhibit Qs comparable to those formed by thin film techniques. For example, Qs in excess of 450 have been observed.
While particularembodiments of the invention have been described, it will be obvious to those skilled in the art that various changes and modifications may be made thereto without departing from the invention in its broader aspects. For example, the total gas flow rate may be varied over wide limits without materially affecting the bond and economic considerations will generally control the acceptable gas flow rate. Further, the partial pressure of the reactive gas in the inert gas also can be varied depending in part on the relative sizes of the materials-to be bonded, the gas flow rate, the presence of reactive elements in the flow system, such as carbon susceptors in the case of an oxygen system, the warm-up rate prior to bonding and the presence of residual oxygen or water in the bonding system and bonding time. Therefore, it is intended that the appended claims cover all such changes and modifications as fall within the true spirit and scope of our invention.
What we claim as new and desire to secure by Letters Patent of the United States is:
1. Av method of direct bonding a metallic member to a non-metallic refractory material substrate, said method comprising the steps of:
placing said metallic member in contact with said non-metallic material substrate; providing a reactive gas atmosphere which at an elevated temperature will react with the metal surface to form a eutectic;
heating the member and substrate to a temperature below the melting point of the metallic member in said reactive atmosphere to form said eutectic with said metallic member which wets the member and the substrate; and
cooling the member and the substrate with the member bonded thereto.
2. The method of claim 1 wherein said metallic member is selected from the group consisting of copper, nickel, cobalt, iron and chromium and the step of heating in a reactive atmosphere forms said eutectic with the selected metallic member.
3. The method of claim 2 wherein said reactive gas is oxygen.
4. The method of claim 2 wherein said reactive gas is a sulfur-bearing gas.
5. The method of claim 2 wherein said reactive gas is a phosphorus-bearing gas.
6. The method of claim 1 wherein said substrate is alumina or beryllia and the metallic member is copper.
7. The method of claim 6 wherein said copper member is in the form of a sheet having a thickness of between approximately 1 and 250 milli-inches and said reactive atmosphere is argon, helium or nitrogen with approximately 0.01 to 0.5 per cent by volume of oxygen.
8. The method of claim 7 wherein said eutectic is copper-copper oxide which forms at a temperature of approximately 1,065C.
9. The method of claim 2 wherein said metallic member has a thickness of between approximately 1 and 250 mils.
10. The method of claim 2 wherein said non-metallic material is selected from the group of alumina, beryllia and fused silica, titanates and spinnels.
11. The method of claim 1 further comprising placing a second non-metallic material in contact with said metallic member to bond said nommetallic materials together.
12. The method of claim 1 further comprising placing a second metallic member in contact with said nonmetallic material to form bonds on opposite surfaces of said non-metallic material.
13. The method of claim 1 wherein the step of cooling is followed by selective masking and etching of the metallic member.
14. The method of claim 1 wherein said reactive atmosphere includes a partial pressure of a reactive gas in excess of the equilibrium partial pressure of the reactive gas in the metal at or above the eutectic temperature.
15. The method of claim 1 wherein said metallic member is selected from the group of alloys consisting of copper-nickel, nickel-cobalt, copper-chromium, copper-cobalt, iron-nickel, silver-gold and berylliumcopper.
16. A method of bonding a metallic member to a non-metallic member comprising:
placing a metallic member selected from the group consisting of copper, nickel, cobalt, iron and chromium in contact with a non-metallic member; providing a reactive gas atmosphere which at an elevated temperature will react with the metal surface to form a eutectic;
forming said eutectic with said metallic member in said reactive atmosphere at a temperature below the melting point of the members; said eutectic wetting said metallic and non-metallic members; and
cooling said members to form a bond therebetween.
17. The method of claim 16 wherein the step of cooling is followed by bonding a semiconductor device to said metallic member.
18. The method of claim 16 wherein the step of cooling is followed by patterning said metallic member.
19. The method of claim 16 wherein the step of forming a eutectic comprises:
flowing a mixture of a substantially inert gas with approximately 0.01 and 0.5 per cent by volume of a reactive gas over said metallic and non-metallic members.
20. The method of claim 19 wherein said reactive gas is oxygen in a percentage of between approximately 0.03 and 0.1 by volume of the reactive atmosphere.
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|U.S. Classification||228/188, 361/779, 174/259, 174/252|
|International Classification||C04B37/02, C23C10/00, C23C8/10, C23C8/12, H05K3/38, C23C10/28, H01L21/70, C23C16/44|
|Cooperative Classification||H05K3/38, C04B37/021|
|European Classification||H05K3/38, C04B37/02B|