EP0336944B1 - Kupfer-wolfram-metallmischung sowie verfahren - Google Patents

Kupfer-wolfram-metallmischung sowie verfahren Download PDF

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Publication number
EP0336944B1
EP0336944B1 EP88908854A EP88908854A EP0336944B1 EP 0336944 B1 EP0336944 B1 EP 0336944B1 EP 88908854 A EP88908854 A EP 88908854A EP 88908854 A EP88908854 A EP 88908854A EP 0336944 B1 EP0336944 B1 EP 0336944B1
Authority
EP
European Patent Office
Prior art keywords
copper
sec
weight percent
tungsten
degrees centigrade
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP88908854A
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English (en)
French (fr)
Other versions
EP0336944A1 (de
EP0336944A4 (de
Inventor
James B. Oenning
Ian S. R. Clark
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
WITEC CAYMAN PATENTS Ltd
Original Assignee
Witec Cayman Patents Ltd USA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US07/212,861 external-priority patent/US4988386A/en
Application filed by Witec Cayman Patents Ltd USA filed Critical Witec Cayman Patents Ltd USA
Publication of EP0336944A1 publication Critical patent/EP0336944A1/de
Publication of EP0336944A4 publication Critical patent/EP0336944A4/de
Application granted granted Critical
Publication of EP0336944B1 publication Critical patent/EP0336944B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/045—Alloys based on refractory metals

Definitions

  • the present invention relates to metal admixtures and processes for making them. More particularly, the present invention relates to copper-tungsten admixtures having from approximately 5 to 50 weight percent copper made by an injection molding and liquid sintering process.
  • packages In the high performance electronics area and particularly in military and space applications, it is customary to put microcircuit chips in hermetically sealed containers, which are known as "packages". These packages must of necessity have electrically insulated leads which extend through the walls of the package. The leads must be hermetically sealed and electrically insulated.
  • the electronic packages generally are designed to contain heat generating components, so it is highly desirable to have the package constructed of materials which have a high thermal conductivity.
  • the packages must be hermetically sealed in order to protect the electrical components which are contained therein. Because these packages travel from sea level to the vacuum of outer space and back in a matter of minutes, any gas leakage is intolerable.
  • the materials used to seal the openings through which the electrical leads pass are inelastic and have coefficients of thermal expansion which are substantially different from those of most metallic materials. Thus, thermal cycling causes stress in the seal and contributes to its rapid failure.
  • composition of matter comprising a high density copper-tungsten admixture which has a high thermal conductivity and a rate of thermal expansion which can be matched to that of many inelastic insulation-seal materials such as glass and ceramics.
  • the high density copper-tungsten admixture is very impervious to gas.
  • the copper-tungsten composition is produced according to the present invention by a powder metallurgical process which involves injection molding to form complex shapes and uses a liquid-phase sintering step to densify the part.
  • a powder metallurgical process which involves injection molding to form complex shapes and uses a liquid-phase sintering step to densify the part.
  • Such molding processes have in general been proposed before; see for example, Wiech, U.S. patent Nos. 4,374,457, 4,305,756 and 4,445,956. Reference is invited to these prior Wiech patents for the disclosure of such procedures.
  • Powder metallurgical procedures which involve injection molding and liquid phase sintering have the capability of producing net-shaped parts in very complex configurations to very close tolerances.
  • Net-shaped parts are those parts or products which do not require any further machining, shaping or forming beyond the liquid sintering phase to be useful for their intended purposes.
  • the tolerances which can be achieved are less than +/- 3mm per metre (0.003 inches per inch). Since the product is injection molded, the shapes of the parts can be extremely complex.
  • a hermetically sealed elctronic package is defined as having a helium gas leak rate of no greater than 1 x 10 ⁇ 9 cm3 of helium per second.
  • the copper-tungsten admixture products of this invention generally exhibit leak rates as low as 2 x 10 ⁇ 10 cm3 of helium per second.
  • the "hermeticity" of electronic packages constructed from this material is substantially in excess of that which is required.
  • the thermal conductivity of the copper-tungsten admixture according to the present invention is generally better than 1.67J.cm ⁇ 1.sec ⁇ 1.K ⁇ 1 and preferably at least 1.76J.cm ⁇ 1.sec ⁇ 1.K ⁇ 1 (0.4 and 0.42 calorie cm/cm2 secs degrees centigrade respectively) measured at a temperature of approximately 390 degrees centigrade. This thermal conductivity is measured for a material which contains about 5 weight percent copper. When less than 5 weight percent copper is present, the benefits of the present invention are generally not fully realized.
  • the thermal conductivity is generally more than 2.51J.cm ⁇ 1.sec ⁇ 1.K ⁇ 1 and preferably at least 2.72J.cm ⁇ 1.sec ⁇ 1.K ⁇ 1 (0.6 and 0.65 calorie cm/cm2 secs degrees centigrade respectively) measured at a temperature of approximately 390 degrees centigrade.
  • the thermal conductivity is generally more than 3.14J.cm ⁇ 1.sec ⁇ 1.K ⁇ 1 and preferably at least 3.35J.cm ⁇ 1.sec ⁇ 1.K ⁇ 1 (0.75 and 0.80 calorie cm/cm2 secs degrees centigrade respectively) measured at a temperature of approximately 390 degrees centigrade.
  • concentrations of copper greater than 50 weight percent the full benefits of the present invention are generally not realized.
  • the linear coefficient of thermal expansion is generally directly proportional to the volume percent of copper in tungsten.
  • a value of about 7.0 parts per million/degree centigrade corresponds to 11 weight percent copper and 9.4 parts per million/degree centigrade corresponds to about 25 weight percent copper.
  • the linear coefficient of thermal expansion of the copper tungsten material according to the present invention can generally be matched to that of the insulator-seal material in the electronic package by adjusting the percentage of copper in the admixture.
  • the thermal performance of the copper-tungsten material products of the present invention particularly when considered in light of the hermeticity and the production of these materials in net-shaped configurations very significantly advances the art.
  • the provision of a net-shaped product eliminates many of the previous requirements for machining and assembling electronic packages. Since the assembling of electronic packages according to previous teachings often involved brazing and soldering steps which permitted the opportunity for gas leaks, the elimination of most such steps according to the present invention greatly improves the reliability of electronic packages.
  • the use of the present invention makes it possible to increase the power density of the package while maintaining the same or improved reliability.
  • the electrical leads which conduct electrical current into and out of the electronic package from the same copper-tungsten material according to the present invention.
  • the thermal performance of the leads may thus be matched to that of the case. Since the high density copper-tungsten material is a good electrical conductor, the electrical efficiency of the package is also excellent.
  • the copper and the tungsten raw materials for use according to the present invention are provided in very finely divided form and in a highly pure state.
  • the particle sizes of the copper material are less than 20 microns and the average particle size of the tungsten powder is less than 40 microns. Preferably, the average particle size for these materials is below ten microns.
  • the amount of surface oxygen on the particles has a substantial impact on the nature of the finished product. At surface oxygen concentrations of more than 5,000 parts per million on the copper, the results are very erratic and unpredictable during the sintering phase. Also, the surface oxygen concentration on the tungsten particles should be less than 1,500 parts per million. In general, the particles are substantially equiaxed in shape. The impurities in the raw materials should be kept to an absolute minimum.
  • a high purity copper-tungsten material was prepared with 35 weight percent copper and 65 weight percent tungsten.
  • the tungsten powder had an average particle size between 1 and 2 microns, surface oxygen of less than about 1,400 parts per million and other impurities of approximately 300 parts per million.
  • Copper powder having an average particle size of between 8 and 10 microns, surface oxygen of less than 800 parts per million, determined by hydrogen weight loss, and other impurities less than 500 parts per million was used. Both the tungsten and copper powder particles were substantially equiaxed.
  • a binder consisting of 39.47 weight percent polypropylene, 9.74 weight percent carnuba wax, 48.73 weight percent paraffin wax and 2.06 weight percent stearic acid was prepared.
  • the binder was admixed in the proportion of 4.3 weight percent with the above copper-tungsten powders.
  • the admixing was accomplished under a vacuum so as to encourage the binder to wet the particulate surface and eliminate entrapped air, thus reducing the porosity and improving the thermal properties of the final product.
  • the resulting admixture of binder and metal powders was injection molded to produce a product having the desired shape.
  • the product called a green part, was heated in air to a temperature of about 207 degrees centigrade for a period of two days to remove the wax.
  • the resultant intermediate product was then heated in an atmosphere containing 25 percent by volume hydrogen and 75 percent by volume of nitrogen at temperatures up to about 800 degrees centigrade until the polypropylene was removed.
  • the temperature was then raised to about 1,235 degrees centigrade and held there for about three hours in an atmosphere containing 75 percent by volume hydrogen and 25 percent by volume nitrogen.
  • the resultant sintered net-shaped product was allowed to cool for approximately six hours to room temperature.
  • the hermeticity of these shaped products exhibits a leak rate of about 2 x 10 ⁇ 10 cm3 of helium per second.
  • the copper content was reduced to 15 weight percent and the tungsten increased to 85 weight percent.
  • the same type of powders described in the first example were again used.
  • the mixing, injection molding, and debinding procedures were again the same.
  • the sintering temperature was increased to 1,450 degree centigrade.
  • the physical properties of interest were determined.
  • the linear thermal coefficient of expansion was 7.56 parts per million per degree centigrade and the density was 15.3 grams per cubic centimeter. The density is 94 percent of full theoretical density.
  • a high purity copper-tungsten material was prepared which had 25 weight percent copper and 75 weight percent tungsten.
  • the tungsten powder which was utilized had an average particle size of between 1 and 2 microns, surface oxygen of less than 1,400 parts per million and other impurities of 300 parts per million.
  • the tungsten and copper powders were proportioned so that 25 weight percent copper and 75 weight percent tungsten were utilized.
  • the metallic powder was admixed with the binder in proportions such that 4.3 weight percent of the resulting admixture was binder material.
  • the admixing was accomplished under a vacuum so as to encourage the binder to wet the particulate surface and eliminate entrained air, thus reducing the porosity and improving the thermal properties of the final product.
  • the resulting admixture of binder and metal powders was injection molded to produce a product having the desired shape.
  • the product, called a green part was heated in air to a temperature of about 207 degrees centigrade for a period of two days to remove the wax.
  • the resultant intermediate product was then heated in an atmosphere containing 25 percent by volume hydrogen and 75 percent by volume of nitrogen at temperatures up to about 500 degrees centigrade until the polypropylene was removed. The temperature was then raised to about 1235 degrees centigrade and held there for approximately three hours. The resultant sintered net-shaped product was allowed to cool for approximately six hours.
  • the thermal conductivity was determined to be 2.08J.cm ⁇ 1.sec ⁇ 1.K ⁇ 1 (0.496 calorie-cm/cm2 sec. degrees centigrade) at about 390 degrees centigrade.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Powder Metallurgy (AREA)
  • Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)

Claims (6)

  1. Eine Substanzzusammensetzung, die durch das Metallspritzgießverfahren ausgeformt wird und folgendes umfaßt:
    ein Kupfer-Wolfram-Material, das im wesentlichen aus 5 bis 50 Gew.-% Kupfer und dem Rest Wolfram besteht und das hermetische Abgeschlossenheit mit einer Leckrate von weniger als 1 x 10⁻⁹ cm³ Helium/s, eine thermische Leitfähigkeit bei 390 Grad Celsius in dem Bereich von mehr als 1,67 J·cm⁻¹·s⁻¹·K⁻¹ bei etwa 5 Gew.-% Kupfer bis 3,64 J·cm⁻¹·s⁻¹·K⁻¹ (0,40 und 0,87 Kalorie-cm/cm²·s·Grad Celsius, entsprechend) bei etwa 50 Gew.-% Kupfer und einen linearen Ausdehnungskoeffizienten aufweist, der direkt proportional zu dem Volumen von Kupfer in dem Bereich von 5,5 Teilen pro Million/Grad Celsius bei etwa 5 Gew.-% Kupfer bis 11,7 Teilen pro Million/Grad Celsius bei etwa 50 Gew.-% Kupfer ist.
  2. Eine Zusammensetzung nach Anspruch 1, bei der das Material eine geringe Leckrate aufweist, die wenigstens so niedrig wie nur 2 x 10⁻¹⁰ cm³ Helium/s ist.
  3. Eine Zusammensetzung nach Anspruch 1, bei der die Zusammensetzung in einer endgültigen Form einer hermetischen Umhüllung ist.
  4. Eine Substanzzusammensetzung nach Anspruch 1, bei der die Zusammensetzung in einer endgültigen Form einer elektronischen Baugruppenpackung ist mit einer Wärmeleitfähigkeit in dem Bereich von 1,76 J·cm⁻¹·s⁻¹·K⁻¹ (0,42 Kalorien-cm/cm²s·Grad Celsius) bei etwa 5 Gew.-% Kupfer, 2,51 J·cm⁻¹·s⁻¹·K⁻¹ (0,60 Kalorien-cm/cm²·s·Grad Celsius) bei etwa 25 Gew.-% Kupfer bis 3,64 J·cm⁻¹·s⁻¹·K⁻¹ (0,87 Kalorien cm/cm²·s·Grad Celsius) bei etwa 50 Gew.-% Kupfer.
  5. Ein Pulvermetallurgie-Spritzgießverfahren, bei dem Flüssigphasensinterung verwendet wird, um Produkte mit endgültiger Form zu bilden, das folgendes umfaßt:
    Auswählen eines Kupferpulvers mit einer mittleren Teilchengröße von weniger als 20 Mikrometer, weniger als 5.000 Teilen pro Million Oberflächensauerstoff und weniger als 500 Teilen pro Million anderen Vernunreinigungen;
    Auswählen eines Wolframpulvers mit einer mittleren Teilchengröße von weniger als 40 Mikrometer, weniger als 1.500 Teilen pro Million Oberflächensauerstoff und weniger als 300 Teilen pro Million anderen Verunreinigungen;
    Zusammenmischen dieser Wolfram- und Kupferpulver unter Vakuum mit einem Bindematerial, um eine Mischung zu bilden;
    Spritzgießen dieser Mischung, um eine vorherbestimmte Rohform zu bilden;
    Befreien der Rohform vom Bindematerial und Sintern dieser Rohform in flüssiger Phase, um ein endgültig ausgeformtes Produkt herzustellen.
  6. Das Pulvermetallurgie-Spritzgußverfahren nach Anspruch 5, das das Auswählen eines Wolframpulvers mit einer Teilchengrößeverteilung einschließt, die so ist, daß die Kompaktheit der Mischung maximalisiert wird.
EP88908854A 1987-09-28 1988-09-21 Kupfer-wolfram-metallmischung sowie verfahren Expired - Lifetime EP0336944B1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US10174987A 1987-09-28 1987-09-28
US101749 1987-09-28
US212861 1988-06-29
US07/212,861 US4988386A (en) 1988-06-29 1988-06-29 Copper-tungsten metal mixture and process

Publications (3)

Publication Number Publication Date
EP0336944A1 EP0336944A1 (de) 1989-10-18
EP0336944A4 EP0336944A4 (de) 1990-01-08
EP0336944B1 true EP0336944B1 (de) 1993-05-12

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP88908854A Expired - Lifetime EP0336944B1 (de) 1987-09-28 1988-09-21 Kupfer-wolfram-metallmischung sowie verfahren

Country Status (9)

Country Link
EP (1) EP0336944B1 (de)
JP (1) JP2811454B2 (de)
KR (1) KR960013889B1 (de)
AU (1) AU615964B2 (de)
CA (1) CA1302739C (de)
DE (1) DE3881030T2 (de)
FI (1) FI86604C (de)
IL (1) IL87859A (de)
WO (1) WO1989002803A1 (de)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4217531C1 (de) * 1992-05-27 1993-12-16 Wieland Werke Ag Verfahren zur Herstellung schlickergegossener isotroper Verbundwerkstoffe auf Kupferbasis mit geringem thermischem Ausdehnungskoeffizienten und hoher elektrischer Leitfähigkeit sowie deren Verwendung
DE69432546T2 (de) * 1993-09-16 2003-11-20 Sumitomo Electric Industries Metallgehäuse für Halbleiterbauelement und Verfahren zu seiner Herstellung
DE102004032853A1 (de) * 2004-07-07 2006-02-16 Rexroth Star Gmbh Linearwälzlager
CN109746455B (zh) * 2019-03-19 2022-08-12 湖南恒基粉末科技有限责任公司 一种含铜kovar合金及其制备方法
CN117802378B (zh) * 2024-02-29 2024-04-30 东北大学 一种具有多尺度结构的钨铜复合材料及其制备方法

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3685134A (en) * 1970-05-15 1972-08-22 Mallory & Co Inc P R Method of making electrical contact materials
JPS54152172A (en) * 1978-05-22 1979-11-30 Mitsubishi Electric Corp Contact for vacuum breaker
JPS5578429A (en) * 1978-12-06 1980-06-13 Mitsubishi Electric Corp Contact material for vacuum breaker
JPS59224306A (ja) * 1983-05-13 1984-12-17 日本碍子株式会社 セラミツク部品の製造法
DE3426916A1 (de) * 1984-07-21 1986-01-23 Vacuumschmelze Gmbh, 6450 Hanau Verfahren zur herstellung eines verbundwerkstoffes
JPH0718651B2 (ja) * 1985-08-02 1995-03-06 電気化学工業株式会社 耐熱ブロツク

Also Published As

Publication number Publication date
CA1302739C (en) 1992-06-09
KR900700216A (ko) 1990-08-11
AU615964B2 (en) 1991-10-17
FI892568A0 (fi) 1989-05-26
KR960013889B1 (ko) 1996-10-10
WO1989002803A1 (en) 1989-04-06
JPH02501316A (ja) 1990-05-10
DE3881030D1 (de) 1993-06-17
EP0336944A1 (de) 1989-10-18
IL87859A0 (en) 1989-03-31
EP0336944A4 (de) 1990-01-08
JP2811454B2 (ja) 1998-10-15
FI86604C (fi) 1992-09-25
FI86604B (fi) 1992-06-15
DE3881030T2 (de) 1993-12-02
AU2531888A (en) 1989-04-18
IL87859A (en) 1991-06-10
FI892568A (fi) 1989-05-26

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