US 3865742 A
A printed microelectronic resistor having excellent stability, high reproducibility and a TCR less than about +/-500 ppm/ DEG C (25 DEG -150 DEG C) is formed from a composition comprised of a glass binder and a silver chloride or cyanide salt free, homogeneous, finely divided powdered admixture of a resistive metal, silver and gold, the powder having a particle size of less than about 5 microns.
Claims available in
Description (OCR text may contain errors)
United States Patent [191 Greenstein 51 Feb. 11,1975
1 1 RESISTOR COMPOSITIONS  Inventor: Bernard Greenstein, Toledo, Ohio  Assignee: Owens-Illinois, lnc., Toledo, Ohio  Filed: May 6, 1971  Appl. No.: 140,988
 US. Cl 252/63.5, 252/514, 29/610, 29/620, 338/224, 338/226, 106/53, 106/54,
117/23, 117/160 R, 117/169 R, 117/169 A, 117/227  Int. Cl.... H0lb 3/02, l-l0lh 85/24, 11010 17/00  Field of Search 252/514, 63.5; 117/227, 117/23, 160 R, 169 R, 169 A; 106/47, 53, 54
 References Cited UNITED STATES PATENTS 3,154,503 10/1964 Janakirama-Rao et a1. 252/514 3,252,831 5/1966 117/227 X 3,407,081 10/1968 252/514 X 3,516,857 6/1970 117/227 X 3,537,892 11/1970 Milkovich et al 117/227 3,634,334 Burgess 252/514 3,681,261 8/1972 Mason 'et a1. 252/514 3,717,453 2/1973 Daiga 75/.5 A
FOREIGN PATENTS OR APPLICATIONS 1,026,577 4/1966 Great Britain 252/514 Primary Examiner-Roland E. Martin, Jr.- Attorney, Agent, or Firm-Richard B. Dence; E. .1. Holler  ABSTRACT 26 Claims, No Drawings RESISTOR COMPOSITIONS This application relates to electronic resistors and methods of making same. More particularly, this invention relates to electronic resistors, compositions, pastes, and methods of making and using same, particularly within the environment of microelectronic circuitry.
As explained in commonly owned cope'nding applica- 1 tion Ser. No. 58,740 filed July 27, 1970, now US. Pat. No. 3,681,261, the art has long known of the value of palladium oxide (PdO) for use as a resistor material, particularly in microelectronic circuitry. Generally speaking, palladium oxide is formed into a resistor by admixing palladium with a glass binder and organic vehicle to form a printing paste. In the case of microelectronic circuitry, the paste is then printed onto a dielectric substrate such as aluminum oxide or the like by the use ofa screen or mask of the desired mesh and formed to provide the desired pattern. The patterned design is then fired in air to oxidize the Pd to PdO and form the ultimate resistor lamina.
In order to increase the negative temperature coefficient of resistivity (hereinafter referred to as TCR), to regulate ultimate resistivity, and to render the stability of the PdO system acceptable, certain metals are employed in admixture with the palladium in the paste. Such metals, which are referred to hereinafter as stabilizers, are those which do not oxidize at the temperatures used to fire the printed paste.
Many problems attend these prior art PdO resistor systems. One major problem is the great sensitivity of these systems to the firing process as a whole. Slight fluctuations or variations in the firing temperature, for example, greatly change the resistivity of the resulting product. Air flow and firing times are further variables to which the ultimate characteristics of the final product are extremely sensitive. Such sensitivity, of course, renders these PdO systems extremely difficult to reproduce. Not only is reproducibility low, but for some reason, not entirely understood, stability is also very low.
The term stability is well-understood in the art and is used herein in accordance with this well-known meaning. This is to say, stability defines that characteristic of a resistor which enables it to maintain its resistivity within tolerable limits over extended periods of time and use.
While the stabilizer metals used in admixture with the palladium oxide generally provide commercially tolerable stability to the system, they are generally found to detrimentally increase the TCR of the systems, usually far above the i ppm/"C level ideally desired. In some instances, especially when Ag is used, stability must be sacrificed for acceptable TCR while, on the other hand, TCR must be sacrificed for acceptable stability. In almost all instances, reproducibility, regardless of the metal stabilizers used, is detrimentally low.
In order to overcome these problems, the art has sought out many solutions. Some have sought to use various additional additives to improve the system. Others have sought to alter the starting materials employed such as by employing finely divided palladium oxide in the paste or initially employing crystalline palladium or its oxide within critical particle sizes and surface areas. Others used combinations of the above solustances, only a modicum of success was actually achieved. In many other instances, the manufacture was rendered so expensive as to make it economically undesirable.
In fulfillment of the need arising out of the abovedescribed problems, commonly owned copending application Ser. No. 58,740 filed July 27, 1970, now US.
,Pat. No. 3,681,261 provides the art with a valuable technique for forming resistive metal oxide systems of the PdO type which are highly stable, reproducible, and have excellent TCR values. The entire disclosure of this last-mentioned patent is incorporated herein by reference.
Generally speaking the resistor compositions are formed in accordance with this last-mentioned patent by:
a. forming an admixture of a resistive metal-organometallic compound, at least one metal stabilizer in organometallic form and: an anti-agglomerating agent which will remain in the system throughout processing;
b. heating the admixture at a sufficient temperature and for a sufficient period of time to drive off the organo-constituents and concentrate the admixture to a powder; and
c. heating the powder at a sufficient temperature and for a sufficient period of time to alloy said metals and in some instances to oxidize the resistive metal.
The powder resulting from step (b) is an admixture extremely homogeneous in nature, which upon alloying in step (c) results (because of this high homogeneity) in a uniquely insensitive base material from which stable, reproducible resistors can be formed having low absolute TCR values. While only one stabilizing metal may be employed, it was found to be preferred to use at least two of these metals together in amounts which were found to synergistically reduce their effect upon TCR. Thus, by using two metals in combination, excellent stability is attained without unduly increasing TCR.
Examples of preferred admixtures in parts-by-weight ratio for minimization of the effect upon TCR were disclosed as including Ag:Au about 4:1 1:4; PtzAg; about 8:1 l:8; and PtsAu, about 8zl-lz8. Particularly preferred was the AgzAu'admixture since it was found that this admixture when alloyed with Pd will form a single phase alloy, thus further minimizing the effect of firing on the system.
While the technique of US. Pat. No. 3,681,261 hereinabove described is extremely valuable, it has a few drawbacks attendant with it which make the findings of an alternative technique for forming highly homogeneous resistive powders and an alternative technique for forming resistor compositions therefrom most desirable. Examples of such drawbacks include the relatively high expense of the organo-metallic compounds used as starting materials and the pollution and danger caused by the volatalization of the organo-constituents during heating to powder form. It has also been found that many of the commercially available organometallics useful in the practice of that invention contain certain chlorinebearing solvents. During the concentration step (b), the chlorine ions have a tendency to react with the silver metal and thereby form silver chloride precipitate which contaminates the resulting powder. For the purposes of this invention wherein electronic, and more particularly microelectronic, resistors are formed, silver chloride, in any substantial amounts, can
not be tolerated in the system since it has a highly detrimental effect upon stability and the physical structure of the ultimate product.
Concurrently filed, commonly owned, copending application Ser. No. 141,006 filed May 6, 1971, now U.S. Pat. No. 3,717,453 in the name of Valdis R. Daiga and entitled POWDERS OF METAL, SILVER AND GOLD AND PROCESSES FOR MAKING SAME fulfillsthe above-described need of an alternative technique for forming highly homogeneous resistor pow ders since it eliminates the problems caused by the use of organometallics. The entire disclosure of U.S. Pat. No. 3,717,453 is incorporated herein by reference.
Generally' speaking this copending application discloses two alternative techniques for forming extremely homogeneous powders of at least one other metal with silver and gold. In one technique, silver chloride or cyanide is present, albeit in reduced amounts, in the. final product. Such a technique and powder formed therefrom are not contemplated for use in this invention..- The second alternative technique of U.S. Pat. No.
3,7l7,453 forms a non-contaminated powder which.
may be used as the preferred starting material for this invention. Generally speaking, this second alternative technique of this copending application, as adapted for the purposes of this invention, comprises initially forming a soluble salt solution of at least one resistive metal and silver. To this silver-resistive metal salt solution there is then added a finely divided gold powder usually having a particle size less than about 5 microns, preferably less than about 2 microns and most preferably substantially submicron in size. The solution containing the gold powder, which is not soluble in the salt solution, is then thoroughly mixed, by agitation, to form a slurry of the gold and there is then added thereto a reducing agent for the resistive metal and silver which precipitates metallic metal and silver without any substantial amount of salt being present therein. While some small amount of homogeneity is sacrificed because the gold powder is not precipitated, precipitation of themetal and silver into the slurried gold powder effects a substantial amount of homogeneity to the extent that excellent, reproducible, stable products can be made therefrom for the purposes of this invention.
The powders formed from the above-described technique, because of the soluble nature of the salt formed in solution remain uncontaminated with detrimental silver chloride or cyanide. Such powders, therefore, generally comprise a finely divided substantially homogeneous admixture of at least one resistive metal other than silver or gold, with silver and gold, which admixture is substantially free of silver chloride or cyanide. The particle size of the powder, without comminution, is generally less than about 5 microns and usually is submicron in size. Thus the powder is'said to be finely divided".
The homogeneity achieved, as stated in U.S. Pat. No. 3,7l7,453 is beyond that achievable by mere mechanical comminution alone or combined with single alloying and is usually to the point where the silver and resisa tive metal are actually alloyed together according to x-ray diffraction indications. The term homogeneous is therefore defined, and is so used for this invention, by this description. 1
While the above-described concurrently U.S. Pat. No. 3,717,45 3 fulfilled a first need for a preferred starting material alternative to those formed by the organometallic technique, it was left to this invention to fulfill the second need of providing a resistor composition and technique alternative tothose of the organometallic concept. This invention, most definitely, fulfills this second need.
Generally, speaking, this invention fulfills this second need by providing the art with a resistor composition comprising a glass binder admixed with a substantially homogeneous finely divided, chloride or cyanide salt free powder comprised of at least one resistive metal and at least two stabilizer metals. Preferably, the powder also contains an antiagglomerating agent, which is substantially homogeneously dispersed throughout the powder. lt is also preferred that at least one of the resistive metals be alloyed with at least one of the stabilizer metals as indicated by conventional x-ray diffraction techniques.
Generally speaking, any one or a combination of the conventional resistive metals may be used in the practice of this invention. Examples of such metals include palladium, rhodium, iridium, ruthenium, indium, and mixtures thereof. Because of the economic advantages, ease of processing, good stability, and good reproducibility, the palladium oxide system, and thus palladium, is preferred for the purposes of this invention. Examples of other metals useful in combination with silver and gold include platinum, copper, nickel and mixtures thereof.
Any of the well-known stabilizing metals may be used in the practice of this invention. Generally, these metals are chosen for their inertness to oxygen at the operating conditions of this invention. The stabilizer metal systems of this invention include at least two metals used together in amounts which have been found to synergistically minimize their effect upon TCR. Examples of these stabilizing metal systems include admixtures of silver, gold, and platinum. Examples of preferred admixtures in parts-by-weight ratio for minimization of effect on TCR include AgzAu, about 4: 1-] :4; Pt:Ag, about 8:l-l :8; and PtcAu, about 821-128. Particularly preferred for the purposes of this invention is the AgzAu admixture since it is found that this admixture when alloyed with Pd will form a single phase alloy, thus further minimizing the effect of firing on the system, thereby increasing reproducibility.
The anti-agglomerating agents useful for the purposes of this invention are those conventional materials which are inert to the system and which will not burn out at alloying and/or firing temperatures. Such antiagglomerating agents are usually of a fine particle size, i.e., less than about 5 microns and usually submicron in size. Examples of these agents include: ultrafine alumina, ultrafine TiO and other ultrafine refractories. Preferred for the purposes of this invention is ultrafine silica which is purchasable under the trademark CAB- O-SlL and has a submicron particle size.
This invention also envisions the use of other additives, known in the art, to the above ingredients in order to enhance, in a known fashion, one or more of the desired characteristics of the system.
Because the silver-gold stabilizer system is particularly preferred for the purposes of this invention and because the only known way to safely form a noncontaminated (free of silver chlorides or cyanides) homogeneous, finely divided powder of a resistive metal (e.g. palladium) with silver and gold is disclosed in the above-described U.S. Pat. No. 3,7l7,453, the tech nique and powders disclosed therein and incorporated herein by reference, are preferred for the purposes of this invention. This is not to say, however, that these are the only powders contemplated for use herein. Quite to the contrary, U.S. Pat. No. 3,717,453 solves a particular problem relative to silver and gold, and other noble metal combinations experiencing similar difficulties. In those instances where other stabilizer systems are employed, which systems are dissolvable in a common solution with the resistive metal without the formation of a contaminating insoluble salt of the chloride or cyanide type, simple tri-precipitation with a known reducing agent or combination of reducing agents may be effected to achieve the contemplated and necessary degree of homogeneity for the purposes of this invention. While co-precipitated powders alone or admixed with a vitreous binder are known (as exemplified by U.S. Patent No. 3,385,799 and 3,390,981 and British Patent No. 1,004,653), triprecipitated powders having a combination of two synergistically active stabilizer metals are believed to be unique to this invention.
The glass binders useful in this invention are any of the conventional glass binders employed by the art. Examples of these binders include the borosilicates and particularly the lead-alumina borosilicates. An example of such a binder includes by weight about:
SiO 8-l 2% E203 20-30% Aigogy 27% ZnO 2030% PbO 30-40% Constituent Range Specific Example PbO 40-75 59 SiO -40 31 Bi O O-lS 2 BaO 0-15 8 Bi O BaO 2-30 10 other oxides less than about 10 substantially 0 An example of ther oxides include A1 0 CaO, ZrO and the like. These glasses have been found to form excellent structures of high cosmetic quality when they are employed in the requisite amounts.
Many of the glass binders contemplated by this invention, such as those of the borosilicate type, do not adversely affect the absolute value of TCR in the system and may therefore by employed alone without additive adjustment. On the other hand, the TCR effect of the preferred zinc free, boron free, lead barium silicate glasses of this invention is highly positive. Such a TCR effect can be neutralized by the addition to the system of a metal oxide which has a highly negative TCR. Examples of such metal oxides include, SnO Cr O Bi O and TiO Preferred for the purposes of this invention is MnO which is highly negative and thus need be employed in only small amounts.
The amounts of each ingredient employed in the resistor compositions of this invention will vary over a wide range depending upon the various characteristics desired in the ultimate product, the various sub-systems and metals etc. employed and the like. Generally speaking, the preferred use for the resistor compositions of this invention is in the microelectronic printed resistor art wherein a microelectronic resistor pattern in paste form is first printed in a desired pattern and then fired to its ultimate structure. The resistors so formed preferably exhibit a stability factor of less than about LI% drift during normal load life (e.g. WOO-10,000 hrs.) and have a TCR of less than 1': 500 ppm/C, preferably less than i 200 ppm/C and most preferably about at 0 ppm/C (i.e. less than about lOO ppm/C), measured at 25-l50C. ln the most preferred embodiments the above characteristics of an individual resistor system are reproducible usually on the order of about i 20% or less.
in the achievement of the above, the metal content of the metal powder should be comprised by weight percent of about 595% by weight of the resistive metal system, preferably palladium alone, and preferably in amounts of about 15-75% and, most preferably about 20-65%. The remainder of the metal content usually consists of the stabilizer metal system, in weight ratios as described, to minimize effect on TCR.
In those instances where an anti-agglomerating agent is employed, it is usually employed in amounts of about 05-15% by weight of the total metal powder. In a PdO system, for example where the stabilizer system in an admixture of silver and gold, it is preferred to use a finely divided silica (submicron particle size) antiagglomerating agent in an amount of about 5% by weight of the total metal powder composition.
The amount of glass binder employed with the abovedescribed powder and the amount of TCR neutralizing oxide will usually depend upon the desired resistivity of the final product and the degree to which its TCR must be reduced toward zero. In those instances where the above-described preferred systems are employed, the general range of constituents for the resistor composition includes by weight about 40-95% glass binder and 5-60% metal powder. In those instances where a TCR neutralizing oxide such as Mn0 is employed it, usually is employed in relatively low amounts such as, for example, about 0.02-0.5% of the metal powder. In those instances where low resistivities on the order of about 1-400 ohms is desired in the final product, the resistor composition preferably comprises by weight about: -55% glass binder and 55-45% metal powder. For higher resistivities greater than 400 ohms and generally about 400-20,000 ohms, the composition preferably comprises by weight about: -85% glass binder and 15-50% metal powder.
The above-described resistor compositions of this invention may be formulated by intimately blending particles of glass binder, usually less than about 5 microns in size with the metal powder. This may be accomplished by any conventional means such as by comminution and ball milling. Best results are achieved with as high a dispersion degree or blending as is reasonably possible. In those instances where a TCR neutralizing oxide is employed, it is usually added in small particle form (i.e. less than about 5 microns) to the particulate glass and powder prior to the blending operation so that it too becomes intimately dispersed throughout the composition.
It has been quite unexpectedly found that the unoxidized resistor compositions of this invention, particularly where the metal powder consists of less than about 50% by weight of the resistive metal system, are relatively insensitive, in and of themselves, to oxidation during normal firing processes for microelectronic resistors. For example, the formation of a resistor from paste form using the unoxidized composition usually results in a resistivity of only a few ohms. This is particularly true when the preferred glass binders of this invention are employed such that firing is conducted at about 725775C. Thus comminution, care not to disturb the oxidized structure prior to firing and the like,
do not play as large a role in the achievement of reproducibility and insensitivity to firing process fluctuations as they did in the aforementioned US. Pat. No. 3,681,26l, or in the prior art referred to therein. For this reason several alternatives are available for controlling, with good reproducibility, the amount of resistivity obtained. Firstly, oxidation of the resistive metal in the metal powder may be carried out either before or after the powder is blended with the glass binder. Preferably, oxidation is carried out after initial blending but prior to ball milling, if such is employed, in order to prevent agglomeration problems. Oxidation is effected by conventional techniques, usually by heating the composition in air to a temperature high enough to effect oxidation, but not high enough to retard it. Such temperatures are usually on the order of about 300-650C. Temperatures which will cause the flow of the glass binder or cause it to sinter should not be employed. Generally, for the preferred glass binders of this invention, oxidation is carried out below about 500C to avoid any problem of flow or sintering.
One alternative for controlling resistivities is to effect only that degree of oxidation necessary to achieve the desired resistivity. Since the remaining unoxidized composition is relatively insensitive to fluctuations in the firing process, resistivity will usually only change less than a few ohms during firing. Generally speaking, substantially complete oxidation is obtained for most systems of this invention when the systems are heated in air for about 4-16 hours at 300650C. Thus, simple trial and error at shorter times will lead to a specific set of operating conditions to obtain a particular resistivity for each individual system.
A second alternative is to oxidize a resistive composition completely and then blend into it, either before or during printing paste formation, a prescribed amount of unoxidized composition to obtain the desired resistivity. Again, simple trial and error will dictate specific blends for each system. Since the unoxidized composition is generally insensitive in and of itself to firing fluctuations, resistivity will not change to any meaningful extent due to variations in firing temperatures, etc., during firing.
A third alternative is, to combine the first two alternatives described above. Of these three alternatives, the second one is preferred as it is most convenient, easy to regulate, and less subject to fluctuations and variations that may occur during the oxidation step.
The above-described resistor compositions may be employed in a wide variety of ways and environments for their resistive properties. Any of these ways and environments, conventional in the art, are contemplated by this invention. As alluded to hereinabove, a preferred way in which these resistor compositions may be used is to formulate them into printing pastes and print them on appropriate substrates for use in microelectronic circuitry. 1
Printing pastes contemplated by this invention comprise an organic liquid vehicle in which the resistor composition is dispersed. Any of the conventional organic liquid vehicles may be employed. A particularly preferred vehicle for the purposes of this invention is a mixture comprised of by weight of a mixture of 2 parts by weight butyl carbitol acetate (diethylene glycol monobutyl ether acetate) to 1 part by weight isoamyl salicylate and 15% by weight of ethyl cellulose. The amount of vehicle to composition employed will vary over a wide range depending upon the physical dimensions and characteristics of the ultimate resistor desired. Generally speaking, the resistor composition is employed in an amount of about 52 parts by weight to 1 part by weight vehicle.
The paste is formed by thoroughly blending the particulate resistor composition with the vehicle by mixing and roller milling. The paste so formed may then be printed in a desired pattern using a conventional screen or mask. Thereafter, the printed design is dried and fired to produce the final resistor, usually upon a dielectric substrate. Drying after printing may be effected by either air drying and/or oven drying, usually at a temperature of about l0Ol25C for about 5-l0 minutes. Firing is usually accomplished thereafter at the temperatures indicated above (e.g. 650-775C) using a heat-up, peak, and cooldown cycle of about 20-60 minutes with firing at peak temperatures for about 2-15 minutes.
As stated hereinabove, the resulting printed resistors, of this invention are found to be highly reproducible, have excellent stability, and generally have TCRs less than :L 500 ppm/C, usually less that $200 ppm/C, and in some instances, substantially close to 0 ppm/C.
The following examples are presented as illustrative of this invention:
EXAMPLES l-l3 Resistors were formulated from the following ingredients and by the following process:
A homogeneous palladium, silver, gold metal powder consisting of by weight 35% Pd, 52% Ag and 13% Au, which was substantially free of any silver chloride or cyanide was formulated according to Example 2 of the aforementioned US. Pat. No. 3,717,453. X-ray analysis indicated that the Pd and Ag were alloyed while the Au was merely dispersed. The particle size of the powder was in the submicron range. A particulate glass binder consisting of, by weight, 59% PhD, 31% SiO 2% Bi O and 8% BaO was blended by mixing into the metal powder and ball milling was employed after oxidation.
Oxidation in air was carried out at the indicated time and temperature where indicated. In those examples which indicate the use of MnO (particle size less than 5 microns), this was blended simultaneously with the glass binder into the metal powder. The blends were formulated into pastes by admixing 3 parts by weight solids with l.l parts by weight of a liquid organic vehicle consisting of 85% by weight of 2 partsby weight butyl carbitol acetate to 1 part by weight iso-amyl salic- Design Reference Dimensions in Mils Width Length Thick Small 40 40 0.7 Medium 80 80 0.7 Large 200 200 0.7 1 5 The following results were obtained using conventional measuring techniques. Resistance was measured by a conventional digital ohmmeter. TCR was measured by measuring resistance at room tem. (25C), then heating the resistor to 150C and again measuring resistance. TCR is then calculated by taking the resistance change in ohms times 10 divided by the resistance at C times 125C. This is represented by the formula TCR (ARX loo Raw 125C) I 25 EXAMPLE 14 Example l was reconducted except that the gold 5 powder employed in making up the metal powder was commercially obtained from Englehard Industries and had an average particle size of about [-2 microns. The results were as follows:
TABLE B Firing Resistance TCR Temp. (ohms/sq.) (ppm/C) Small Med. Large Small Med. Large 725 336 372 467 +84 +73 +68 750 394 489 593 +90 +88 +84 775 391 484 722 +57 +68 +61 In addition to showing the flexibility of this invention in being able to use various starting materials, the example, compared with example I, shows the reproducible nature of the resistors of this invention.
Once given the above disclosure, many other fea- TABLE A No. Formulation Firing Resistance (ohms/sq.) TCR (ppm/C) Ox. Ball (Metal/glass/ Temp. C Small Med. Large Small Med. Large Time/ Mill MnQ wt. ratio) Temp.
1. 10/10/.009 725 390 450 510 36 33 33 400C 24 hrs. 750 400 475 540 65 67 57 4 hrs. 24 hrs. 775 430 550 640 81 76 72 24 hrs. 2. 10/10/008 725 220 236 284 +140 +156 +157 750 331 363 463 +117 +129 +130 4 hrs. 16 hrs. 775 410 489 617 +115 +122 +130 400C 3. 10/20/.008 725 1250 1250 1400 +152 +157 +165 750 1800 1900 2400 +125 +142 +138 do. do. 775 2500 3200 4000 +114 +121 +127 4. 10/10/.009 725 1.4 1.6 2.1 N O 750 .8 .9 1.1 1g 16 hrs. 775 1.1 1.2 1.6 5. 10/10/.0080 725 317 337 407 +61 +59 +61 16 hrs. 16 hrs.
750 423 500 634 +48 +53 400C 775 517 596 797 +47 +39 6. Blend-30% No. 4 725 170 198 257 +28 +20 +16 70% No.5 750 132 152 222 0 5 +10 (Wt. 71 775 275 274 412 5 0 -10 7. Blend-10% No. 4 725 262 292 351 +34 +42 +45 -9()71 No. 5 750 269 300 385 +44 +45 (Wt. 70 775 481 525 631 +39 +35 +33 8. l/l/0 725 95 +482 +499 +518 4 hrs.
750 65 62 +516 +397 +541 400C None 775 45 45 65 +473 +456 +497 9. 20/80/0 725 10M 10M 10M 7.50 50K 70K K +452 +433 +415 4 hrs. None 775 16K 18K 18K +560 +560 +600 450C 10. 20/80/0085 725 400C 750 8.8K 11.9K 15.2K +284 +279 +280 4 hrs. 16 hrs. 775 5K 6.2K 7.7K +246 +244 +248 11. Blend-30% No. 1 725 2.1K 2.4K 2.7K +82 +89 +90 70% 750 2.85K 3.4K 3.86K +87 +76 +90 (wt. Va) 775 3.871( 4.431( 4.76K +97 +63 +63 12. Blend-70% No. 1 725 1.21K 1.45K 1.6K +64 +75 +76 30% No. 3 750 1.75K 1.9K 2.1K +66 +75 +80 (wt. 775 2.3K 2.8K 3.0K +47 +45 +50 13. Same as 725 1.76K 1.99K 2.47K +126 +121 +129 16 hrs. Ex. 3 except 750 2.6814 3.06K 3.79K +113 +114 +119 400C oxidized for 775 3.66K 4.09K 4.97K +98 +102 +103 16 hrs/400C In addition to the above generally excellent electrical properties, the resistors were found to be stable and reproducible as, defined hereinabove.
tures, modifications, and improvements will become apparent to the skilled artisan. Such other features, modifications and improvementsare considered to be a part of this invention, the scope of which is to be determined by the following claims:
1. A resistor composition comprising a particulate zinc free, boron free, lead, barium silicate glass binder having a tiring temperature of about 725-775 C and a positive TCR, said glass binder being admixed with a substantially homogeneous finely divided, substantially chloride or cyanide salt-free powder comprised of at least one resistive metal selected from the group consisting of palladium, rhodium, iridium, ruthenium, indium and mixtures thereof, at least two stabilizer metals selected from the group consisting of silver, gold and platinum, and about 0.02-0.5 weight percent, related to the weight of the metal powder, of particulate Mn to reduce the TCR of said resistor composition.
2. A resistor composition according to claim 1 in which a metal selected from the group consisting of platinum, copper, nickel and mixtures thereof are combined with silver and gold.
3. A resistor composition according to claim 1 having a TCR less than about 200 ppm/"C (25 150C), wherein said resistor composition comprises about 40 95 weight percent of a glass binder having a particle size of less than about microns, wherein said glass binder comprises by weight about: 40 75% PbO, l5 40% SiO 0 Bi O and 0 15% B210 and wherein about 2 is Bi O BaO and the listed oxides constitute at least about 90% by weight of the glass composition, and about 5 60% of said metal powder, said MnO having a particle size less than about 5 microns.
4. A resistor composition according to claim 3 wherein said powder also includes about 5 weight percent of a silica having a particle size of less than about 5 microns as an anti-agglomerating agent substantially homogeneously dispersed throughout the powder.
5. A resistor composition according to claim 4 wherein said glass binder consists essentially of by weight about: 59% PbO, 31% SiO 2% 131 0,, and 8% BaO.
6. A resistor composition according to claim 5 wherein said powder consists of by weight: Pd, 52% Ag and 13% Au.
7. A resistor composition according to claim 4 having a TCR less than about 100 ppm/C (25 150C.)
8. A resistor composition according to claim 1 wherein said stabilizer metals are selected from an admixture of the following metals in the indicated weight ratios: AgzAu, about 4:1-1 :4; PtzAg, about 8:1-1 :8; and PtzAu, about 8:l-l:8.
9. A resistor composition according to claim 1 wherein said powder also includes an antiagglomerating agent substantially homogeneously dispersed throughout the powder, said anti-agglomerating agent being a refractory having a particle size less than about 5 microns.
10. A resistor composition according to claim 3 wherein at least one of said resistive metals is alloyed with at least one of said stabilizer metals.
1]. A resistor composition according to claim 1 wherein said resistive metal is palladium.
l2. A resistor composition according to claim 11 wherein said stabilizer metals are Ag and Au in a weight ratio of about 4:l-l:4.
13. A resistor composition according to claim 12 wherein Ag is alloyed with Pd.
14. A resistor composition according to claim 1 wherein said glass binder comprises by weight about: 40-75% PbO, 15-40% SiO ,,0-l5% Bi O and 0-15% BaO wherein about 2-30% is Bi O BaO and the listed oxides constitute at least about by weight of the glass composition.
15. A resistor composition according to claim 14 wherein said glass binder consists essentially of by weight about: 59% PbO, 31% SiO 2% Bi o and 8% BaO.
16. A resistor composition according to claim 1 wherein said powder is comprised of by weight about 595% of at least one resistive metal and 5% by weight of said at least two stabilizer metals.
17. A resistor composition according to claim 16 wherein said resistor metal is palladium in an amount by weight of about 15-75% of said powder.
18. A resistor composition according to claim 17 wherein said palladium is in an amount by weight of about 20-65% of said powder.
19. A resistor composition according to claim 16 wherein said powder also includes an antiagglomerating agent in an amount by weight of about 05-15% of said powder, said anti-agglomerating agent being substantially homogeneously dispersed throughout the powder and said anti-agglomerating agent having a particle size less than about 5 microns.
20. A resistor composition according to claim 19 wherein said anti-agglomerating agent is finely divided silica in an amount by weight of about 5% of said powder.
21. A resistor composition according to claim 33 which comprises by weight about 40 95% glass binder and about 5 60% metal powder.
22. A resistor composition according to claim 1 wherein said powder was formulated by initially forming a soluble salt solution of at least one resistive metal and silver, adding to said solution a finely divided gold powder having a particle size of less than about 5 microns, forming a slurry of said solution and gold powder, and adding a reducing agent to said slurry to precipitate metallic silver and resistive metal.
23. A resistor composition according to claim 22 wherein said resistive metal is palladium.
24. A printing resistor paste comprised of a liquid organic vehicle and the composition of claim 1.
25. A printing resistor paste according to claim 24 wherein said vehicle consists essentially of diethylene glycol monobutyl ether acetate, iso-amyl salicylate and ethyl cellulose.
26. A printing resistor paste according to claim 25 wherein said resistor composition is in an amount of about 5-2 parts by weight per 1 part by weight of said vehicle.
UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,865, 742
DATED February ll, 1975 INVENTOR(S) B.Greenstein lt'is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Col. 3, line 14, delete "this copending application" and insert therefor -U.S.Patent No. 3,7l7,453-; line 25, delete "of this copending aoplication". Col. 5, line 53, delete "ther" and insert therefor -othe: line Y 60, delete "by" and insert therefor be. Col. 8, line 23, after "vehicle" insert --usually.
Signed and Scaled this A ttes t:
RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner oj'latents and 'Trademarks UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,865, 742
DATED February ll, 1975 INVENTOR(S) B.Greenstein lt'is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Col. 3, line 14, delete "this copending application" and insert therefor U.S .Patent No. 3, 7l7,453-; line 25, delete "of this copending aoplication". Col. 5, line 53, delete "ther" and insert therefor other line 60, delete "by" and insert therefor --be. Col. 8, line 23, after "vehicle" insert -usually.
Signed and Scaled this Nineteenth Day of April 1977 [SEAL] AIICSI.
RUTH C. MASON C. MARSHALL DANN Atltsting Office Commissioner oflarenls and Trademarks