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Publication numberUS3358196 A
Publication typeGrant
Publication dateDec 12, 1967
Filing dateJun 8, 1966
Priority dateJun 8, 1966
Publication numberUS 3358196 A, US 3358196A, US-A-3358196, US3358196 A, US3358196A
InventorsJr John J Steinmetz, Pasquale A Trongo
Original AssigneeWestinghouse Electric Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Pressure multiple electrical contact assembly for electrical devices
US 3358196 A
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Description  (OCR text may contain errors)

Dec. 12, 1967 J. J. STEINMETZ, JR. E TAL 3,358,196 PRESSURE MULTIPLE ELECTRICAL CONTACT ASSEMBLY FOR ELECTRICAL DEVICES Filed June 8 1966 2 Sheets-Sheet 1 FIG.4.

WITNESSES INVENTORS John J. Sfeinmefz,Jr 8 a K (AA/aw Pasquale A.Trongo B Y '27 2% M ATTmEY Dec. 12, 1967 J. J. STEINMETZ, JR, ETAL 3,358,196 PRESSURE MULTIPLE ELECTRICAL CONTACT ASSEMBLY FOR ELECTRICAL DEVICES Filed June 8 1966 2 Sheets-Sheet 2 United States Patent 3,358,196 PRESSURE MULTIPLE ELECTRICAL CONTACT ASSEMBLY FOR ELECTRICAL DEVICES John J. Steinmetz, In, Monroeville, and Pasquale A.

Trongo, Greenshurg, Pa, assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed June 8, 1966, Ser. No. 556,206 9 Claims. (Cl. 317-234) This invention relates to a pressure multiple electrical contact assembly suitable for use in compression bonded electrical devices.

An object of this invention is to provide a pressure multiple electrical contact assembly for electrical devices wherein an electrical connection is made to each of at least two contact surfaces of a mesa-type semiconductor element and at least one of the electrical connections incorporates a stress relief member to reduce the stresses caused by thermal changes within the electrical device.

Another object of this invention is to provide a pressure multiple electrical contact assembly which distributes the force applied to the contact assembly uniformly over the mesa-type configuration surfaces of semiconductor elements in physical contact with the contact assembly while providing electrical contact means to each surface of the mesa-type configuration as required and at least one of the electrical contact means incorporates a means for reducing the effects of thermal stressing within the electrical contact means.

Other objects of this invention will, in part, be obvious and will, in part, appear hereinafter.

In order to more fully understand the nature and objects of this invention, reference should be had to the following description and drawings, in which:

FIGURE 1 is a top view of a partially deformable cushioning member embodying the teachings of this invention;

FIG. 2 is a side view, partially in cross-section, of a portion of an electrical contact assembly employing the partially deformable cushioning member of FIGURE 1;

FIG. 3 is a side view, partially in cross-section, of another portion of an electrical contact assembly employing the partially deformable cushioning member of FIG- URE 1;

FIG. 4 is a side view, partially in cross-section; of a portion of a compression bonded electrical device employing the portions of the electrical contact assembly of FIGS. 2 and 3;

FIG. 5 is a top view of the semiconductor element employed in the device shown in FIG. 4; and

FIG. 6 is a side view, partially in cross-section, of a compression bonded electrical device employing the portion of the compression bonded electrical device shown in FIG. 4.

In accordance with the present invention and in attainment of the foregoing objects, there is provided a pressure multiple electrical contact assembly comprising a partially deformable cushioning member having two major opposed surfaces, the member having a plurality of apertures, each aperture extending completely between the opposed surfaces, at least two electrical contacts, each contact being threaded through a separate portion of the plurality of apertures, at least one contact having an integral expansion element contained therein, an electrical lead affixed to the expansion element of each electrical contact having an expansion element and and electrical lead afiixed to each of the other electrical contacts.

In order to more fully describe this invention, and for no other purpose, a pressure multiple contact assembly having only two electrical contacts, only one of which incorporates a stress relief member, will be described as one illustrative example of the use of the contact assembly in pressure electrical devices.

With reference to FIG. 1, there is shown a top view of a partially deformable cushioning member 12 embodying the teachings of this invention and particularly suitable for use in compression bonded encapsulated electrical devices.

The cushioning member 12 has a top surface 14 and a bottom surface 16. The member 12 has a plurality of apertures 18, 26, 22, 24, 26 and 28 extending between surface 14 and surface 16 disposed therein.

The cushioning member 12 consists of a material which can be partially deformed to match or compensate for any unevenness in any surface which comes in contact with the surfaces 14 and 16 of the member 12.

The material of the member 12 has properties which will allow it to cold flow under pressure. The cold flow proceeds only to a given limit and then essentially ceases, whereupon the member 12. acts as a rigid member.

Upon assuming the property of a rigid member, the material of the member 12 then transmits the applied force without any further appreciable restrictive cold flowing occurring. During operation of an electrical device at a temperature level as high as 200 C. to 250 C. but preferably lower and a pressure preferably exceeding 800 pounds per square inch, the allowable further deformation of a member 12 is as little as possible in order to protect the functional reliability of the electrical device in which the member 12 is utilized.

Preferred materials having the desired properties mentioned above are polytetrafluoroethylene and trifiuoromonochloroethylene. These two materials in addition to having the desired properties, also are good electrically insulating materials for the operating range of devices up to approximately 250 C.

With reference to FIG. 2, a first electrical metal contact 30 is threaded through apertures 18, 20, 22 and 24 of the member 12. Although the contact 30 may have any desirable cross-sectional geometric shape, a rectangular or square metal strip is preferred for use in compression bonded electrical devices. The flat surfaces of the contact 30 provides a better distribution of forces and also provides a large electrical contact surface area.

The contact 30 comprises a metal selected from the group consisting of copper, gold, nickel, silver, tin, indium and base alloys thereof.

The contact 30 is formed in a manner which allows those portions of the contact 36 in contact with the sur' faces 14 and 16 to be flat, parallel to, and touching, the respective surfaces of the member 12. This configuration for the contact 30 permits handling of the assembly without fear of the contact 3% dropping out of the member 12.

An integral expansion portion 32 is provided in the contact 36 to allow for the restricted flowing of the material comprising the member 12 and to compensate for any thermal and mechanical stresses which may occur in the contact 30. An electrical lead 34 is affixed to the expansion element 32 to provide a means to connect the contact 30 to an electrical system external to the assembly.

With reference to FIG. 3, there is shown a second metal electrical contact 36 threaded through apertures 26 and 28. The preferred cross-section of the contact 36 is square or rectangular. The contact 36 comprises a metal selected from the group consisting of copper, gold, nickel, silver, tin, indium and base alloys thereof.

Like the first contact 30, the contact 36 is formed so that the portions of the contact 36 in contact with the surfaces 14 and 16 lie flat, parallel to, and touching, the respective surfaces of the member 12. This configuraof gold, silver, tin, .then be disposed between, -coated surface 48 and the electrical contact60 Without employing a bonding material toform a permanent joint between the components.

3 tion prevents the contact 36 from falling out of the member 12 during any handling and also provides a large electrical contact surface area for connecting to an electrode. Anelectrical lead 38 is affixed to one end efthe contact 36 to provide-a meansfor connecting'the contact-36 into a remote electrical system.

With reference to FIG. 4, there is shown a portion of a compressionbonded semiconductor device utilizing the teachings of this invention.

The portionof the device is comprised of an electrically and thermally conductive support member 42, made of a metal selected from the group consisting-of copper, silver, aluminum,-base alloys thereof-and ferrous base alloys. Copper and brass, a-base alloy of copper, 'have been-found particularly satisfactory for this purpose.

The support member 42 has a peripheral flange 44 and an upwardly extending pedestal portion 46. The upwardly extending pedestal portion 46'has an uppermost mounting surface 48. Theperipheral flange 44has a-top surface 50 and the upwardly extending pedestal portion 46 has a peripheral side surface 52.

An upwardly extending hollow cylindrical member 54 is affixed tothe support member 42. The inner periphery of the member 54 conforms to theperipheral surface 52 of the pedestalportion .46. Themember54 is afiixed to thesupport member. 42 byany suitable means 'knownto those skilled in the art, such, for example, as .by disposing a suitable braze material 56 between the topsurface i) ofthe fiange44 and the side surface 52 of the pedestal portion.4.6 and aportion of the inner pheriphery and all of the bottom of the cylindrical mem- The cylindrical member 54 is preferably made of a *ferrousbaeematerial althoughother suitable materials,

aluminum. The layer 58 simultaneously compensates for any surface irregularities which may occur on the .surface 48 andthe mating surface of. an electrical contact6t The layer 58 may be disposed uponthe surface 43 by any suitable means known to those skilled in the ,art, such, for example, as electrodeposition-means, or as apreformed disc of, a suitable metal affixed to the surface ;.48 and then contoured to specific requirements.

Anothersuitable method of disposing anequivalent non-reactive, malleable electrically and thermally conductive structure in lieu of the layer.58 is to coat the .surface 48 with a suitable material to promote electrical andthermal conductivity by such suitable means such,

for example, as electro-deposition. A metal member comprisinga metal selectedfrom the group consisting indium, lead and aluminum may and in contact with, the

The electrical contact 60 comprisesa metal, such for example, as molybdenum, tungsten, tantalum and combinations andbase alloys thereof. The contact 60 may also be plated with a suitable material such, for example, as gold.

The contact 60 is a firm supporting structure for a body of semiconductor material. The contact 60 should therefore have good electrical and thermal conductivity properties and a thermal expansion characteristic closely matched to the material comprising the body-of semiconductor material disposed on the contact 60.

A semiconductor element 62 is disposed on the electrical contact 60. The semiconductor element 62 comprises a body of a semiconductor material selected from the group consisting of silicon, silicon carbide, germanium, compounds of Group III and Group V ele- The semiconductor element 62 has a mesa-type structure, or multi-level .electrical contact surfaces. An elec trical contact area 64, with a shape as shown in FIG. 5,

isdisposed on, and in an electrically conductive relationship with the region61 of semiconductivity. A second electrical contact area 66-is disposed on, and in an electrical conductive relationship with the region 65 of semiconductivity. Theelectrical contact-area 64 ofthis element-62 is at a-higher elevation'than'the electrical contact area 66. The contactareas 64 and 66 are also physically separated from each other.

The element 62 is-afiixed to the contact 60 by suitable means such, for example, as by employing a solder layer 68 of an alloy of silver, lead and antimony.

Referring againto FIG. 4, the electrical contacts 30 and -36assembled-in the member 12 is disposed on the semiconductor eleme'ntxiZ. The first electrical contact 30 is aligned, and is in electrical contact, .with the electrical contact164. At the same ti1ne, the second electrical contact --36 is simultaneouslyaligned, and'is in electrical contact, with the other electrical contact .66. Alignment of .the contacts and .36 vwith the respective ohmic contacts;64 Iand 6,6 is relatively simple. The thickness of the cushioning member 12 is thin enough, approximately 15 mils,.so.that.t he member .12 is translucent. One is therefore able to orient the electrical contacts 30 and 36 ,withtherespective ohmic contacts64 and 66 on the surface of. the element'62 quitev easily by.visual means only.

FIG. 4 is also-illustrative of the deformation of'the cushioning member 12. The memberlZ partially deforms under the required force necessary to keep the contacts 30 and 36 and the respective contacts 64 and 66 of the element;62, as well as the element-62, the contact 60 and the support member42 in an electrical and thermal conductivity relationship. This required force causes the material comprising the cushioning member 12 to flow .whereby the member 12 molds itself. to conform to the surface irregularities of the element Y62 and its electrical contacts 64 and 66 as Well as at least partially filling the apertures present within the member 12 and thervoids existing between the assembled. components of the electrical device immediately adjacent to the member 12.

With reference to FIG. 6, there is shown a compression bonded electrical device 70 which incorporates the structure of the portion of the electrical device shown in FIG. 4.

consisting of ceramic, mica, glass, quartz and fluorocarbon.

A first a-pertured metal thrust washer 74 is disposed about the electricalconductors '34 and 38 upon the top surface of the apertured insulating washer 72. At least one apertured metalspring washer 76 is disposed about the electrical conductors 34 and 38 upon the top surface of the thrust washer 74.

A second apertured metal thrust washer 78, similar to, or the same as, the washer 74 is disposed on the uppermost spring washer 76. An-apertured expandable metal retaining ring 80, similar to a snap ring, is disposed about the electrical conductors 34 and 38 within, and is retained wardly extending cylindrical member- 54.

The ring 80 cooperating with the cylindrical member 54 and acting on the thrust washer 78 resiliently urges the apertured spring washer 76 to transmit a compression force through the apertured thrust washer 74 and thence through the apertured electrically insulating washer '72 to force the electrical contacts 30 and 36, the semiconductor element 62, the electrical contact 66 and the uppermost mounting surface 48 of the upwardly extending pedestal portion 46 of the support member 42 into a firm, intimate, electrically conductive relationship with each other.

More than one apertured spring washer 76 of the same, or different thickness, may be required to cooperate with the retaining ring 80 and the cylindrical member 54 to create the necessary compressional force required for a reliable operating device 76.

An electrically non-conducting washer 84 is disposed on the retaining ring 80. The washer 84 has a plurality of apertures 86. Each of the leads 34 and 38 project through an individual aperture 86 of the washer 84. The washer 84 limits the lateral movement of the leads 34 and 38 thusly reducing the associated stresses resulting from the movement from deleteriousl-y affecting the joints between the contacts 30 and 36 and the respective leads 34 and 38.

A molecular sieve 88 is disposed on the washer 84. The sieve 88 has an aperture 99 through which the leads 34 and 38 project. T e sieve 88 is self-centered since its outer peripheral side surface 92 conforms to the inner wall of the member 54. The sieve 88 functions as a moisturegettering device.

The device 70 is completed by providing a hermetic enclosure for the semiconductor wafer 62. The hermetic enclosure is formed by aflixing an apertured header assembly 94 to the member 54. The header assembly 94 comprises an outwardly extended flanged member 96 affixedto a multiple apertured insulating seal member 98.

The header assembly 94 is joined to the member 54 by welding the outwardly extended flanged member S t; to an integral annular weld ring 160 formed within the member 54. An upwardly extending integral flange 192 of the member 54 acts as a guide for positioning the header assembly 94 during assembly and joining operations.

The electrical lead 34 passes through a metal sleeve 104 in one of the apertures of the header assembly 94. A hermetic seal is achieved by compressing the sleeve 104 by any suitable means, such, for example as by swaging, rolling and the like, about the portion of the outer periphery of the lead 34 which it encompasses.

The electrical lead 38 terminates in an electrical connector 106 hermetically sealed into the header assembly 94. To electrically connect the lead 38 into an external system, another electrical lead 108, suitably aflixed to the connection 106, is required.

An electrical contact and thermal dissipating stud 110 is either affixed or is integral with the support member 42. The stud 110 is used to connect the support member 42 to an electrical conductor and heat sink.

The following example is illustrative of the teachings of this invention:

A good electrically and thermally conductive support member having an integral electrical contact and thermal dissipating stud was prepared from a piece of copper alloy bar stock. The finished machined configuration was the same as illustrated in FIG. 6. A layer of silver was then aflixed to the uppermost mounting surface of the pedestal portion and machined to a specific flatness and diameter.

A ferrous integral case and weld ring assembly was then affixed to the support member by disposing a layer of braze material between portions of the assembly and the top of the peripheral flange and the side surface of the upwardly extending pedestal portion.

A silicon semiconductor transistor element suitable for use as a compression bonded electrical device was prepared. The element had a top surface which had been divided into two separate distinct regions of semiconductivity. The electrical contact to one semiconductivity region was 0.5 mils higher than the electrical contact to the other region of semiconductivity.

The semiconductor element was affixed to a molybdenum electrical contact by disposing a layer of a silverlead-antimony alloy electrical solder material between the bottom surface of the element and the top surface of the contact. The element and contact, aflixed to each other, was then disposed within the integral case and weld ring assembly and upon the layer of silver on the pedestal.

A polytetrafluoroethylene cushioning member was prepared. The member was about 15 mils in thickness and large enough to cover the entire surface of the semiconductor element. Apertures were formed entirely through the thickness of the member.

A piece of flat silver metal ribbon was threaded through one series of apertures in the cushioning member. A flat tab was formed at the beginning end of the ribbon pressed against the top surface. The ribbon passed down through one aperture and was flattened against the bottom surface of the cushioning member for the entire length to the next aperture. The ribbon transversed the aperture and was formed into approximately a semicircular stress relief loop and passed downwardly through the next aperture. The ribbon was then flattened against the bottom surface of the cushioning member to the next aperture. The ribbon then passed upwardly through this next aperture and the end of the ribbon was formed flat along the top surface of the cushioning member.

Another piece of flat silver metal ribbon, shorter than the first piece of metal ribbon, was then threaded to the next series of apertures in the cushioning member. A flat tab was formed at one end of the ribbon and the rest of the ribbon was threaded downwardly through one aperture until the flat tab was lying flat on the top surface of the cushioning member. The ribbon was then formed flat against the bottom surface of the cushioning member to the next aperture in the series. The ribbon was then passed upwardly through the aperture and the end of the ribbon was formed into a flat tab along the top surface of the cushioning member.

A first silver electrical lead was aflixed to the stress relief loop of the first piece of silver ribbon. A second silver electrical lead was aflixed to a tab of the second silver electrical lead, the tab being closest to the center of the cushioning member.

The resulting structure was the pressure multiple contact assembly shown in FIGS. 1, 2 and 3.

The contact assembly was then disposed within the integral case and weld ring assembly and positioned on top of the semiconductor element. The cushioning mem ber was translucent enough to allow the positioning of the silver metal ribbon electrical contacts on the two aluminum electrical contacts of the semiconductor element.

An apertured ceramic washer was then placed over the silver electrical leads and disposed on the top surface of the cushioning member. The outer periphery of the mica washer conformed with the inner periphery of the integral case and weld ring assembly.

A first steel apertured thrust washer was then disposed about the electrical conductors from the contact assembly and on top of the ceramic washer. The outer periphery of the thrust washer conformed to the inner periphery of the integral case and weld ring assembly. Two apertured steel spring washers and a second steel thrust washer were respectively then disposed about the electrical conductors from the element and on top of the first steel thrust washer. The outer periphery of the spring washers and the second steel thrust washer conformed to the inner periphery of the integral case and Weld ring assembly.

Force was then applied to the second steel thrust washer and a steel retaining ring was snapped into an annular groove in the integral case and Weld ring assembly to keep the spring washers in compression. The theoretical pressure on,the surface of the element was in excess of 800 p.s.i. based on anabsolutely smooth surface.

An apertured polytetrafluoroethylene washer was disposed ontopof the steelretaining ring. The silver electricalleads passed throughthe respective apertures of the washer. The outer periphery of the washer conformed to the inner periphery of the case and weld ring assembly.

After one hour,,the polytetrafluoroethylene washer retaining ringwasremoved and the device was unloaded.

The pressure multiple contact assembly was removed from the device, Examination of the polytetrafluoroethylene cushioning member revealedthat the member had cold flowedunder pressure and molded itself about the irregularities in the surface of and portions of the electrical contacts on the element. An outline of the struc .ture of the element wasclearly impressed in the surface of the member. Thesurfaces of the member had also molded themselves flush with the ribbon contacts contained therein. The semiconductor element, upon visual inspection, was still structurally satisfactory.

Thedevice was reloaded except for a hermetic seal.

The calculated pressure on the theoretically smooth surface area of the element ,was approximately 102.0 p.s.i.

The device was heated to a temperature of about 200 C. for a period of 68 hours. The device was then cooled, the retaining ring I and polytetrafiuoroethylene washer removedand the pressure rnultiple electrical contact assembly removed for an examination.

[The cushioning member of the contact assembly had been permanently deformedabout 10%. The outline of thesemiconductor elements surface and portions of the electrical contacts attached thereto was clearly embossed in the surface of the cushioning member. The surfaces of the memberwere still molded flush-with the ribbon contacts contained therein. Visual examination of the semiconductor .element showed no defects.

The device was reloaded again except for a hermetic seal. A new pressure multiple electrical contact assembly was substituted for the permanently deformed assembly previously used. The pressure applied to the semicon- .ductor element surface was a calculated 1400 psi. The

device was heatedto ateunperature of 200 C. and held .at temperature for approximately two hours. The device wasfthen cooled, the retainingring and the polytetrafluoroethylene washer were removed and the pressure multiple electrical contact assemblyremoved for examination.

The thrust memberhad been permanently deformed approximately 10%.1Th'e structure ofthe semiconductor .element and portions ofthe electrical contact-s attached ,thereto was again clearly embossed in thesurface of the .thrust, member. Visual examination of, the semiconductor ,element, stillrevealed no damage. to the element.

" Employing a new polytetrafluoroethylene thrust member, "mils in thickness, the device was again reassembled A calculated pressure of 1000 p.s.i. Was impressed on the surface. of the semiconductor element. An aperturedmolecularsieve was disposed about electrical leads connected. tothe pressure multiple electrical contact assembly and on the polytetrafluoroethylene washer. The hermetic enclosure shown in FIG. 5 was attached to the integral case and weld ring assembly to form a complete electrical device within which the semiconductor element was hermetically sealed.

The hermetically sealed electrical device was then electrically' cycled through a theoretical operating cycle, typical of what the device would encounter during normal usage. The device continually performed satisfactorily andwell within its design limits.

The device was carefully disassembled and the pressure multiple electrical contact assembly was examined.

The polytetrafluoroethylene cushioning member had been permanently deformed about 10%. The member had molded itself about all the surface irregularities which .had been in contact with the member. The stress relief portion of the one silver metal ribbon had been deformed slightly by the movement of thecushioning member, but theelectrical lead was still firmly attached tothe stress relief portion. i

A visual examination of .the semiconductor element showed the element to be still in satisfactorylcondition.

It was also noted that during all these tests and evaluations, the apertured polytetrafiuoroethylene wlasher ,reduced the accidental fracturing of the slender silver electrical leads to the pressure multiple contact assembly. The washer had reduced considerably the lateral movement of the slender electricalleads.

A trifluoromonochloroethylene cushioning member and an apertured trifluoromonochloroethylene wlasher were employedin the same type of electrical devices in lieu of their polytetrafluoroethylene counterpartsnEqual- 1y satisfactoryresults were obtained-when the same tests were repeated using these substitutedmaterials.

Although the member 12 haslbeen described as being a circular disk, other geometrical shapes may;-be employed as configurations for the member 12 and will Work equally as well. The geometrical shape required is'determined only by the encapsulating member components, and particularly the design of the semiconductor element employed therein, as well asthe number, and type, of electrical connections required to be ,made to' the wafer.

While the invention has been described withreference to particular embodiments and examples, it will be understood of course, that modifications, substitutions and the like may be made therein without departing from its scope.

We claim as our invention:

1. A pressure multiple electrical contact assernbly comprising (1) a partially deformable cushioning member having two major opposed surfaces, the member having a plurality of apertures, each aperture extending completely between the opposed surfaces, (2) at least two electrical group consisting of polytetra-fiuoroethylene and trifluo ro monochloroethylene.

3. The pressure multiple electrical contact assembly of claim 1 in which the material comprising the electrical contacts is at least one metal selected from the group consisting of copper, gold, nickel, silver, tin, indium and base alloys thereof.

4. The pressure multiple electrical contact assembly of claim 1 in which the material comprising the partially deformable cushioning member is one selected from the group consisting of polytetrafluoroethylene and trifluoromonochloroethylene and the material comprising the electrical contacts is at least one metal selected from the group consisting of copper, gold, nickel, silver, tin, indium and base alloys thereof.

5. The pressure multiple electrical contact assembly of claim 1 in which the material comprising the partially deformable cushioningmember is one selected from the group consisting of polytetrafluoroethylene and trifluoromonochloroethylene and the material comprising the electrical contacts is silver.

'6. A'semiconductor device comprising (1) a semiconductor element having at least two electrical contacts affixed to one major surface of the element (2) a pressure multiple electrical contact assembly in electrical contact with each electrical contact on the one major surface of the element, the assembly comprising a partially deformable cushioning member having two major opposed surfaces, the member having a plurality of apertures, each aperture extending completely between the opposed surfaces, at least two electrical contacts, each electrical contact being threaded through a separate portion of the plurality of apertures, each of the electrical contacts being in electrical contact with an electrical contact afiixed to the semiconductor element, at least one of the contacts having an integral expansion element contained therein, the electrical contacts each comprising a metal selected from the group consisting of copper, gold, nickel, silver, tin, indium and base alloys thereof, an electrical lead affixed to the expansion elements of each electrical contact having an integral expansion element and an electrical lead afiixed to each of the other electrical contacts, (3) a means for applying a constant force on the pressure multiple electrical contact assembly whereby each of the electrical contacts of the pressure multiple electrical contact assembly are maintained in thermal and electrical conductive relationship with each respective electrical contact aflixed to the semiconductor element.

7. The semiconductor device of claim 6 in which the material comprising the partially deformable cushioning member is one selected from the group consisting of polytetrafiuoroethylene and trifluoromonochloroethylene.

8. The semiconductor device of claim 6 in which the material comprising the partially deformable cushioning member is one selected from the group consisting of polytetrafluoroethylene and trifluoromonochloroethylene and each electrical contact of the pressure multiple electrical contact assembly is made of silver.

9. The semiconductor device of claim 6 in which an apertured electrically non-conducting member is disposed on the means for applying a constant force on the pressure multiple electrical contact assembly, the apertured member restricting the lateral movement of an electrical lead passing through an aperture of the member.

References Cited UNITED STATES PATENTS 2,728,881 12/1955 Jacobi 317-234 3,059,157 10/1962 English et al 317-234 3,296,501 1/1967 Moore 317-234 JAMES D. KALLAM, Primary Examiner. R. F. POLISSACK, Assistant Examiner.

Patent Citations
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US3059157 *Nov 14, 1958Oct 16, 1962Texas Instruments IncSemiconductor rectifier
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3441814 *Mar 30, 1967Apr 29, 1969Westinghouse Electric CorpInterlocking multiple electrical contact structure for compression bonded power semiconductor devices
US3512249 *Aug 22, 1967May 19, 1970Ass Elect IndPressure contact semiconductor devices
US3577042 *Jun 19, 1967May 4, 1971Int Rectifier CorpGate connection for controlled rectifiers
US4543457 *Jan 25, 1984Sep 24, 1985Transensory Devices, Inc.Microminiature force-sensitive switch
US5027192 *Jan 11, 1990Jun 25, 1991Asea Brown Boveri Ltd.Fast power semiconductor circuit
EP0381849A1 *Dec 21, 1989Aug 16, 1990Asea Brown Boveri AgFast power semiconductor circuit
WO1985003383A1 *Jan 24, 1985Aug 1, 1985Transensory Devices IncMicrominiature force-sensitive switch