CA1056031A

CA1056031A - Layered strip connector

Info

Publication number: CA1056031A
Application number: CA226,569A
Authority: CA
Inventors: Leonard S. Buchoff; Joseph P. Kosiarski; Chris A. Dalamangas
Original assignee: Technical Wire Products Inc
Current assignee: Technical Wire Products Inc
Priority date: 1974-05-10
Filing date: 1975-05-08
Publication date: 1979-06-05
Also published as: CH587599A5; GB1505678A; JPH02126578A; DE2520590C2; DE2520590A1; HK82279A; JPS6337463B2; FR2280218B1; JPH0334194B2; FR2280218A1; JPS59230270A; JPS5836513B2; JPS5123673A

Abstract

abstract A layered connector element for electrically connecting two or more sets of electrical conductors which are proximately positioned in a one to one relationship is constructed by assemblying alternately in substantially parallel relationship sheets of electrically conductive material and sheets of elec-trically non-conductive material into a block structure, slicing from the block, in planes perpendicular to the planes of the sheets, a slab containing, alternately, elongated elements of electrically conductive material and elongated elements of electrically non-conductive material, and slitting from the slab in a plane to which the elongated elements of the slab are normal, a layered connector element, the linear dimension of the element perpendicularly transverse to the layers forming the element being at least several times the largest linear dimension of any single layer.

Description

lOS6031 Background of the In~ention l. ~Fie~d of the Invention . .. . .. . . . . . . . . . . . . . . .
This invent~on pertains to resilient, self-aligning, electr~cal connectors having electrical contacts made of metal-filled or carbon-filled, resilient, elastomeric layers inter-posed between non-conductive elastomeric layer~. The invention particularly pertains to methods for maXing layered elastomeric structures used to electr~cally connect t~o or more sets of - electrical conductors proximately positioned in a one~to-one lQ relationship, each set consisting of a plural~ty of closely spaced conductors positionally fixed with respect to each other.

2. Description of the Prior Art Prior art connectors for electrically connecting two or more sets of electrical conductors such as tape cable con-nectors, plug~tn printed circuit board connectors~ integrated circult connectors, liquid crystal display unit connectors and ; the like usually include compllcated assemblie~ that have complex metal contacts for complettng the electrtcal ctrcuits, Some connectors ~nclude sharp-polnted contacts that are forced through insulation or insulating films bending, scratching and stressing the conductors to provide adequate electrical contact. Charac-teristic of most prior art de~ices are complicated electrical eon~acts in the form of ramps, rings, fingers and t~e like made of springy metal material which maintain engagement with the conductors by mean~ of elastic deflection, These types of electrical contacts are usually expensive to make and diffi-cult to assemble into a connector. Additionally, they have the . 2 - ~

, ~

1056~3~

disadvantages of being generally di~ficult to reproducably fabricate and when fabricated, occupying an undesirable amount of volume and subject to fat1gue when under continuous use.
Where two or more sets of electrical conductors are to be connected to each other, each set consisting of a large number of very small conductors closely align~d next to each other, the electrical contacts must in some measure assure exact alignment of ~he conductors so $hat each conductor of a first set w~ll contact only with the correct corresponding conductor or conductors of a second set. This alignment is generally achieved by means of spaced aperturesin the connectors that contain corresponding contacts, Where a large number of contacts are so situated or where repeated making and breaking of the contacts is experienced, misalignment, wear, bending, shorting and other types of circuit failure are commonly exper-ienced. Moreover, permanent or semi-permanent electrical -connections of this type are undesirable or impossible. The metal to metal contacts expertence surface abrasion due to the wiping,action ~f the initial contact which, in time, corrodes :
~0 thereby increaslng the contact resistance. The actual contact- 1, ing area of a metal to metal contact is typically less than one thousandth of the total surface area 'of the metal contact. If permitted, moisture and hostile atmospheres can migrate between the contact surfaces rapidly deteriorating the quality of the electrical contact.
These dlsadvantages can only be overcome ~y providing a ¦ -connector which ts soft and resilient and which sealingly engages the contacts to be connected yet whlch presents su~stantially no surface abrasion during initial contact. It is therefore an object of thls invention to create such a connector which is very simply and reproducibly fabricated from known materials by methods which are susceptible to u~ilization of low skill level manpower, low volume economy of scale and negligible waste of materlals.
Summary of the Invention The present invention relates to a method of making a layered connector element for electrically connect-ing sets of spaced electrical conductors comprising thesteps of: A. assemblying alternately ~n parallel relation-ship sheets of electrically conductive material and sheets of elec~rically non-conductive material, into a block ~tructure, B~ slicing fro~ the block, in a plane perpendic-ular to the planes of the sheets, a slab containing, alternately, elongated elements of electrically conductive ma~erial and elongated elements of electrically non-conductive ~aterial, and C. slitting from the slab, in a plane to which the elongated elementa of the slab are substanti~lly 2~ ~ normal, a layered connector, the linear dimension of the connector along a direction perpendicular to the layer6 and passing therethroug~ being at least several times the largest linear dimens~on of any single layer.
In its apparatus aspect, the invention is useful with a system electrically connecting at least two sets of Rpaced electrical conductors, and comprises a strip of ~ub8tantially parallel alternate layers of conductive and non-conductive cured elastomer~ the linear dimension of the strip along a direction perpendicular to the layers and 30 pa6Bing therethsough being at least several times the largest l~near di~ension of any single layer, A layered strip connector according to this invention can be produced by any of several methods, although ;

~b/~`b_ ~ 4 1056~31 certain me~hods are pre~errcd over others due to economies of scale, adaptability to automation, uniformity and quality control. Generally, a sheet of non-conductive elastomer is sprayed, cast, molded, extruded or calendered and partially or fully cured. A sheet of conductive elastomer is sprayed, cast, molded, extruded or calendered on top of the previous sheet, or sprayed, cast, molded, extruded or calendered separately and placed Dn top of the previous sheet with any necessary binder included. The process of placin~ conductive sheets on top of non-conductive sheets is repeated many times to form à block consisting of a stack of ~heets of an appropriate height. The stack of sheets is then post-cured to effect a binding between all the sheets. The stack is then sllced, approximately perpen-dicular to the sheets, to form slabs containing alternating elongated elements of conductive and non-conductive mater~al.
The ~labs are thenislit in planes to which the elongated elements are substantially normal to form a layered connector ~ --according tD thi~ invention.
A connector made accord~ng to this invention consists essentially of layers of electrically conductive, elas omeric resin (which can be made conductive in any ~nown conventional manner) and non-conductive elastomer~c resin-alternately interposed to form an electrical connection between two or more sets - ', ' .: "
,~

':
~ mb/ ~ - 4a -,, , . . . . , ~ , .. . .

of proximately spaced electrical conduc~ors. The electrical connector element exlsts independe~tly of the sets of conductors as a strip of resilient mater~al co,nsist~ng of a sertes of metal-filled or carbon-filled, elastomer~c resln layers interposed between non-conductive resin layers, the conductive layers forming the electrical contacts of the connector element, Generally, the number of layers per unit length of the c~nnector .
strip will be selected such that at least one conductlve layer and typically a plurality of electrically conductive and non-conductive layers contact each conductor as well as each space between adjacent conductors of any set. Since the number of layers is typically large in comparison to the number of conduc-tors in any gi~en situation, the connector ef~ec~s a self-aligning function by permitting electrical contact only between corres-ponding conductors.of two or more sets connected. The layers are subs~antially parallel to each other ana are approxtmately perpendicular to.the surface of the conductors contacted, The layers need not be of the same thickness and in some applications ~:
particular thicknesses for the conductive and/or non-conductive .
layers can be advantageously established. In general, the linear : dimension of a layered connector perpendicularly transverse to the layers forming the connector is at least se~eral and typioally 10 to 100 times the largest ltnear dimens~on of any ~ingle layer forming the connector.
Elastomers which can ~e sat~sfactorily used ~nclude - i copolymers of butadlene-styrene, butadiene-acrylonitrtle, and butadiene-isobutylene as-well a~ chloroprene polymers, poly-sulfide pol~mers, plasticized vinyl chloride and vinyl acetate polymers and copolymers, polyurethanes and silicone rubbers.
. The ~ilicone rubbers conventionally are dimethyl, methyi-phe~yl, : - 5 -.

1~56~31 methyl-vinyl, or the halogenated slloxanes that are mixed with fillers such as a silica to impart proper rheology and vulcanized or cured with peroxides or metal salts~ Silicone rubber is generally preferred because of its aging characteristics and its retention of physical characteristics at temperature extremes.
The elastomers used should be form stable when partially cured, that is, they should not deform unduly under their own weight, nor should they plastically deform after curihg, but rather should be resiliently renitent.
It is, therefore, preferable that the connector consist only of alternating layers of conductive and non-conductive elastomeric resin, Greater integrity (i.e. unitary nature of the elastomeric material) can be assured by using the same elas-tomeric material for both the conductive and non-conductive layers, the differences in conductivity resulting only from the choice of appropriate fillers.
A non-conductive elastomer is an elastomer having a volume resistivity equal to or greater than 109 ohm-cm. While the res~stivity of the conductive layers can be varied over wide ranges, typically 10-4 to 104 ohm-cm., low resistivity values are preferred to reduce problems such as thermal dissipation and capacitive interference, which can be experienced at the higher resistivity values.
The preferred elastomers for use in both the conductive and nonsconductive layers are the silicone rubbers, to which may have been addea fillers to enhance thelr handllng properties.
Examples of non-conductive silicone elastamers are General Electric Company RTV-615 and Rodhelm-Reiss Compound 4859 Silicone elastomers typically in the absence of co~ductive fillers, have a volume resistivity of 10 4 to 1015 ohm-cm.
and a dielectric strength of about 500 volts per mi1 in a one-eighth inch thick sample.
Conductive elastomers ha~ing higher values of resistivity, 10 to 104 ohm-cm., are generally created by using a carbon-filled ~lastomer. An example of a carbon-filled conductive elastomer is Union Carbide silicone compound K-1516.
Conductivé elastomers having lower values of resistivity, 10 4 to 10 ~hm-cm., are created by incor-porating into the elastomer conductive fillers such as copper, nickel and silver, and metal-coated fillers such as silver-coated copper and silver-coated glass. The metal-filled elastomers may also contain carbon to improve the physical characteristics of compression set and strength. An example of a metal-filled conductive elastomer i s: , .. ... .

- !
Material Wei~ht ~ -'.

Silicone rubber compound -methyl phenyl vinyl s~lDxane gum ~ ~-(General Electric, SE-5211U) 13.0% ;~

2,5-bis (tert-butylperoxy)-2,5-dimethyl-hexa~e carried on inert carrler, 50% active (R. T. Vanderbllt Co., VAROX, a trade mark) 0.1%

Dicumyl peroxide carried on carrier of precipitàted calcium carbo~ate, 40% active ~Eercules, Inc., Di-Cup 40C, a traae mark) 0.1%

Silves powder Average particle diameter, 0.6-3.0 microns Apparent density, 8-16 gmslin3 (Handy & Harmon, SILPOWDER 130, a trade mark) 63.8%

Silver powder Average particle diameter 3.0-4.0 microns Apparent density 16-19 gmslin3 (Metz Metallurgical Corp., EG-200) 11.5%

mb/~ - 7 --Silver flake Average particle d~ameter 10.0 microns Average particle thickness 1.5 microns Apparent denslty 20-27 gms/in3 (Metz Metallurigcal Corp., Ag Flake #6) 11.5%
c~ tr~e r~4~

Examples of other conductive and non-conductive elastomers usable in this invention are to be found in U.S. Patents 3,140,342;

3,412,042; 3,609,104 and 3,620,873.
The resilient character of the elastomers involved assures a good electrical connection with the conductors by elastically deforming in response to external forces such as would be experi-enced upon insertion of the c~nductor set. This effects a vibrational absorbing and cushioning not a~ailable from undamped flexible metal connectors. This damped flexible supporting of the surface of the conductors also hermetically seals the con-ductor surface after contact has been made thereby inhibiting corrosion by preventing the mlgration of hostile fluids to the contacting conductor surface~ The connectors of this invention are easily reproduced over a wide range of contact resistance~
hardness, layer th~ckness and other mechanical and electrical ~ariables, While the thickness of the layers can be varied sub~
stantially depending on the ind~vidual demands of the parttcular situattonr for opt~mum design the layer t~icknesses should Pe chosen so that there are as many conductive layers ~er un~t .length of the resulting connector element as possible,wh~le simultaneously avoiding any electrical malfunction caused ,by the proximity of the adjacent conduct~ve layers under the ntended conditions of use. While satisfactortly perform~ng la~ered strlp connectors can be made with elastomer la~ers as thin as .0003 ~nches and as thick as ,125 inc~es, from practtcal con~
siderations of quality, ease of assembly, economy~ etc,~ the layers need be no greater t~an ,040 ~nches and ~hould pe ~o thtnner than .001 inches . A one~to~one correspondence between the conducttve layers of the connector and the cQ~ductors of 'i one set of conductors may be desirable ~n particular s~tuations, In all situatlons the lndtvidual la~er a~mensions are chosen with regard to the final conne~tor d~me~s~ons such that ~he . llnear dim-engion of the co~nector perpend~cularl~ tran~ver~e to the layers forming the connector i8 at least several times the largest linear dimension of any single layer form~ng the con~ -nector. ~.
The layered connectors made accord~ng to th~s ~nvention can have several configurations, In one embodiment, the connec-tor can oomprise simply a strip of substanttally parallèl alter- j nate layer.s of conductive and non-conducti~e cured elastomer, ,.:
the linear dimension of the str~p perpendicularly transverse to the layers fonming ths strip be~ng at least several t~mes the.
largest linear dimension of any single layer present ~n the strlp, In another embodiment, a plurality of the strips can be combined with means for retaining the strips ~n substantially.
2b fixed relation to one another, One such retain~ng means is formed from antipodally bordering lamina cured or vulcan~zed to the original block of alternately layered conductive and non-con-duc.tive elastomers. Other retaining means may be formed in-dependently of any shape, subject only to conventional choice . of design, A strip ~f substantial~y parallel layers of conduc~
ti~e and non-conducti~e cured elastomer is then bonded to the-peri,phery of the retalning means, Al~ernat~ely~ sla~s o~
elongated elements cut from a block of alternately layered elastomers can be bonded to a central core body. The central core body with the bonded layered elastomer slabs can then be cut in planes perpendicular to the elongated elements comprising , the slabs into individual connectors.
In the broadest sense, the invention comprises means and method for making a means for connecting sets of spaced elec-trical conductors compr~sing recurrent, substantially parallel layer,s of conductive and non-conductive material bonded together in a unit. Particular features and advantages of the invention jl, will become apparent from the following description in conjunc-tion with the preceding summary, the accompanying drawings and ,~
claims.

Brief Description of the Drawings ~, Figure 1 is a sectional view of a layered strip connector according to this invention~
Figure 2 is a perspective view of a block and a slab ' sliced from that block formed in making a connector according to this invention.
Figure 3 is an enlarged detail perspective of the slab of Figure 2 and a connector element slit from that slab.
Figure 4 is an explodea perspective view of an elec-trlcal apparatus being connected to a printed circuit board with a connector according to this invention.
Ftgure 5 is an elevation view of a connector having retaining means formed of antipodally bordering laminae accord-ing to this in~ention, .

1~56~31 Figure 6 is a perspective view of a block and a slab sliced from that bloc~ having antipodally ~ordering laminae according to this invention~
Figure 7 is a schematic representation of a method of forming blocks according to this invention.
F~gure 8 is a perspective view of a body with a plurality of slabs of elongated elements bonded thereto.
Figure 9 ls a perspective view of a connector a~cording to this invention cut from the body illustrated in Figure 8.

Descri tion of the Preferred Embodiments P
As shown in Figure 1, a layered strip connector 10 contains alternate layers of conductive elastomeric resin 12 and non-conductive elastomeric resin 14 bonded together to form a unitary structure. Surfaces 16 and 18 are suitable for contacting sets of approximately positioned conductors (not shown) for elec-trically connecting the sets of conductors, Electrical conduc-tion can take place in either direction, between the surfaces 16 and 18, through the layers of conductive elastomer 12, while substantially no electrical conduction takes place through the layers of non-conductive elastomer 14. The individual conductive layers 12 are therefore insulated from each other.
A connector according to this in~ention is constructed by assemb~ying by molding, casting or some other method a plurality of sheets of conductive and non-conductive elastomers alternately to form a layered b70ck 20 shown in Figure 2. The block is cured sufficiently to ensure physical integrity of the block so as to prevent any layer separation at any subsequent step in the manu facturing procedure or dur~ng use. The cured block 20 ~s ~hen sliced in a plane perpendicular to the planes of the individual sheets ~orming the block to provide slabs 22.

105603~
The slabs 22, shown in more detail in Figllre 3, consist of a plurality of rods of conductive elastomers 24 and rods of non-conductive elastomer 26, bonded together. The rods of conductive elastomer 24 are con-ductive not only through the thickness of the slab 22, but also longitudinally through the length of the conductive rods 24. The slabs 22 are then slit perpen-dicular to the rods 24 to form the connecting strips 10.
The strips 10 can be used either individually or in combination with other similar strips to form layered connectors according to this invention. In generàl, the linear dimension L of the strip 10 perpendicularly transverse to the layers 24 and 26 forming the strip 10 is at least several times and typically 10 to 100 times the largest linear dimension of any single layer 24 or 26. -~
The assemblying of the sheets of electrically conductive and non-conductive material into a block may be performed by several different methods. An example of the production of a block ready for slicing containing ~
carbon-filled silicone rubber for the conductive layers -is as follows: a plurality of insulating sheets 2 in. x

4 in. x .~10 in. were produced from a Rodhelm-Reiss Silicone . . .
Co~pound 4859 catalyzed with 1% Verox (a trade mark) by pressing for one minute at 340F. until partially cured.
Conductive sheets 2 in. x 4 in. x .010 in. were produced from Union Carbide Compound K-1516 catalyzed with 1%
Verox (a trade mark), pressed for one mlnute at 450F.
until partially cured. The conductive and non-conductive sheets we~e stacked alternately to produce a block 1/4 in.
hlgh, Four such blocks were stacked to form a block 1 in.
high. This block was cured in a press for one-half hour at 450F. and post-cured without pressure for 4 hours at 350 F. -~

mb/~o - 12 -The block was then sliced into slabs 2 in. x 1 in. x ~100 in.
The slabs were then sl~t into connecting strips 1 in. x .050 in.
- x .100 ln.. Each layer within the connecting strip had linear outside dlmensions of .010 in. x .050 in, x .100 in. and tne diagonal linear dimension through the center of the layer was calculated to be approx~mately .11~ in. The linear dimension of the connecting 8trip perpendicularly transverse to the layers forming the strip (l--ln.) is, therefore, at least several t~mes the largest linear d~mens~on o~ any single layer ~ ,112 in . ) .
An example of the production of the layered connector containing silver filled silicone rubber is as follows: sheets of non-conductive sil~cone elastomer 2 in. x 4 in. x .010 in.
were produced in the same manner as in the previous example.
Layers of conductive silicone elastomer were produced w~th the formulation set forth in Table 1, ~len~ed and pressed into uncured layers 2 in. x 4 in, x ,010 in. The conductive and non-co~ductive layers were alternately stacked to produce a block 1/4 inch high.
Four such blocks were`stacked to form a block 1 inch high. This blocX was cured at 450~. for one-half hour in a press and then post-cured without pressuse ~or 4 hours at 350F. Thls block was sliced in a manner s~milar to the previous example to form connector strips 1 inch by .050 inches by ,100 inches.
Blocks of sheets suitable for slicing into connectors can : als~ be produ¢ed by fully curing the conductive and non~conduotive ~25 sheet~ of t~e foregotn~ examples sep æ ately, interleafing the sheets of conductive elastomer with those of the non-conductive elastomer with a curable3adhesive therebetween, and subsequently curlng under Fressure ; 105~031 Blocks may also be produced by casting a layer of non-conductive elastomer and partially cuxing that layer, casting a layer of conductlve elastomer onto the non-conductive layer and partially curing the second layer, continuing to cast and cure alternate layers of conductive and non-conductive elastomers until formtng a block of the destred dimension and finally curing the block to ensure that the sheets do not separate. This method may also be used with molding rather than casting.
Another method for producing blocks of sheets suitable for slicing into connectors, according to this invention, com-prises extruding long continuous lengths, typically up to 800 feet and 3 to 5 inches wide, and partiaily curing the long con-tinuous lengths of non-conductive elastomer to a state that it is easily handled and does not deform under ttS own weight, The long continuous strip of non-conductive elastomer shown in Figure 7 as 60 is then used as a base or substratè upon which a continuous layer of electrically conductive elastomer 62 can be extruded or calendered as a continuous layer. The contlnuous layer of conductive elastomer 62,along w~th the strip of non.
c~nductive elastomer 60 is then wound on an octagonal or other similarly shaped drum 64. The drum 64 has sldes 66, typically , " about 10 inches in length. The thickness of the layers 60 and ~ ~ O-V~O
~62 ls typically 4.~a~ inches. The drum 64 is rotated in t~e ~- ' ' direction indicated by the arrow until 50 to 100 layers of the con,ductive and non-conductive elastomer are wound one on top of the other. The drum 64 is then stopped and the multtple layers 68 formed on each surface 66 are removed from the drum ,, 6~ by cutting generally along lines 70. The multtple layers 68 are then cured under pressure, either individually or stacXed together to result in a block -20 as shown in Fiqure 2. Thls 1056C~3~

block can then be sliced tnto slabs 22 and then slit into layered strips 34, as shown in Figure 4.
As illustrated in F1gure 4, an apparatus 30, such as a li~uid-crystal display unit can be électrically connected to a printed circuit board 32 by layered strip connector~ 34. Each of the electrical conductors 36 on the printed circuit board 30 is roughly positloned to correspond with a conductor on the display unit 30. The electrically conductive layers of the connector 34 permit electrical current to travel between each of the corresponding conductors. The non-conductive layers prevent electrical current from traveling to non-corresponding conductors. The number of layers present in the connector 34 is typically several times the number of conductors 36 on the printed circuit board.
The resilient character of the elastomers used in pro-ducing the connector 34 cushions and absorbs shock and vibration between the apparatus 30 and the circuit board 32. The smooth compliant surface of the connec~or 34 seals the surface of the conductors 36 after contact inhibiting contact corrosion.
A connector 40, illustrated in Figure 5, consisting of a number of layered connector elements 42 retained in substantially fixed relation to one another by retaining means 44 can be advantageously used in the place of the independent strip con-nectors 34 of Figure 4. The retaining means can be either con-ductive or non-conductive as the particular situation might demand~

A connector such as connector 40 can be conveniently made by sandwiching a layered block of elastomers 38, similar to block 20 of Figure 2~ between two laminae 46 as shown in Figure 6. The two laminae 46 can be made of any desired materials and can be multilayered, but to achieve greatest strength preferably are made of single layers of an elastomer which is fully compatible with the elastomers used to form the individual layers of block 38. The layered block of elastomers 38 and the antipodally bordering laminae 46 are cured or vulcanized together to form a single block 48 from which slabs 50 can be sliced.
The slab 50 consists of elongated elements 52, similar to rods 24 and 26 of Figure 2, which are formed from the layered elastomers 38 and are alternatingly conductive and non-conductive, bounded by bordering elements 54 formed from the laminae 46.
One or more connectars 40, illustrated in Figure 5, can be cut, stamped, punched or otherwise formed from slab 50~ The waste from this process can be used to form other layered connectlng elements generally-according to this invention. The bordering elements 54 of slab S0 form the retaining means 44 of connector 40. The connector 40 can be viewed as a slab 50 having at least one inside edge 56 defining an orifice through the slab.
Another connector according to this invention, having particular utility in connecting very small, fraglle electrical circult elements such as integrated circuit chips and the like can be made by bo~dlng one or more slabs 22 of elongated elements of alternately conductive and non-conductive elastomer 24 and 26 to a body 72, as shown in Figure 8. The body 72 is preferably an elastomer fully campatible with the elastomers orming the slabs 22. The body 72 acts as a retaining means 44 for sub-stantially fixing the phys.ical relationship between the slabs 1056~31 22. The body 72 and slabs 22 are then cut in planes to which the layers of conductive and non-conductive elastomer 24 and 26 are essentially perpendicular; thus, generating the connector 74 shown generally in Figure 9.
~he connector 74 comprises a central portion 76 ha~ing upper and lower surfaces 78 and 80, respectively, bounded by and joined by a periphery 82. Ftxed to the periphery is a plurality of strips 10, each strip comprising alternate layers ` of electrically conducttve and electrically non-conductive elastomer, each layer extending between and being cotermin s with the upper and lower surfaces 78 and 80. The central portion 76 can be tailored to have any shape desired, whether it ~e rectangular, circul æ , or other convenient shape. ~he central portion 76 functions as a retaining means 44 to fix the physical.relation-sh~ps between the two strips 10. The upper ana lower surfaces 78 and 80, while generally being parallel to each other, can be skewed, one with respect to another, in certain circumstances.
In general, the area of the periphery 82 is less than the area of either the upper surface 78 or lower surface 80. Further, the linear dimension of each strip 10 transversely perpendicular to the alternate layers 24 and 26 forming the str~p 10 is at .
least several times the greatest linear dimension of any of the alternate layers forming the strip, Although the inventton has been described in considerable detail with reference to certain preferred embod~ments thereof, it will be understood that variatiOns and modifications can be effected withi~ the spir~t and scope of the tnvention as des-cribed above and as defined in the attached claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of making a layered connector element for electrically connecting sets of spaced electrical conductors comprising the steps of:
A. assemblying alternately in parallel relationship sheets of electrically conductive material and sheets of electrically non-conductive material, into a block structure, B. slicing from the block, in a plane per-pendicular to the planes of the sheets, a slab containing, alternately, elongated elements of electrically conductive material and elongated elements of electrically non-conductive material, and C. slitting from the slab, in a plane to which the elongated elements of the slab are substantially normal, a layered connector, the linear dimension of the connector along a direction perpendicular to the layers and passing therethrough being at least several times the largest linear dimension of any single layer.

2. The method of Claim 1 wherein the step A comprises the steps of:
1) casting an incompletely cured sheet of elec-trically non-conductive elastomer, 2) casting an incompletely cured sheet of elec-trically conductive elastomer on top of the sheet formed in step 1), 3) continuing to cast alternately sheets of non-conductive and conductive elastomer on top of the sheets pre-viously formed until a stack containing the desired number of sheets of elastomer is obtained, and 4) completely curing the stack of elastomer sheets into a single block structure.

3. The method of Claim 2 wherein molding is performed in any instance where casting might otherwise be performed.

4. The method of Claim 1 wherein the step A comprises interleafing cured layers of elastomer with an incompletely cured elastomer to form a stack of alternating layers of cured and uncured elastomer, and curing the stack into a single block structure.

5. The method of Claim 4 wherein the cured layers of elastomer are non-conductive and the incompletely cured elastomer is electrically conductive when subsequently cured.

6. The method of Claim 1 wherein the step A comprises the steps of:
1) extruding an incompletely cured sheet of elec-trically non-conductive elastomer, 2) forming an incompletely cured sheet of elec-trically conductive elastomer on top of the sheet formed in step 1), 3) winding the two strips together on a multi-faceted drum, thereby forming stacks of alternately electrically conductive and electrically non-conductive elastomer, one stack on each facet of the drum, 4) removing each stack from the drum and curing under pressure into a block structure.

7. The method of Claim 1 wherein step B further com-prises bonding a plurality of said slabs to a body such that the slabs are fixed with respect to each other and the alter-nately elongated elements of each slab are essentially parallel to each other.

8. The method of Claim 7 wherein step C
comprises slitting from the plurality of slabs fixed to the body, in a plane to which the elongated elements of the slabs are substantially normal, a plurality of layered connector strips and means for retaining the connector strips in fixed relation one to another, the linear dimension of each connector strip along a direction perpendicular to the layers and passing therethrough being at least several times the largest linear dimension of any single layer in any strip.

9. An electrical connector for connecting at least two sets of spaced electrical conductors, the connector having a plurality of layered strips, each strip comprising substantially parallel alternative layers of electrically conductive and non-conductive cured elastomer, each layer extending through the connector between two surfaces adapted to receive the two sets of spaced electrical conductors, the linear dimension of each strip along a direction perpendicular to the layers and passing therethrough being at least several times the largest linear dimension of any single strip.

10. In a system electrically connecting at least two sets of spaced electrical conductors, a strip of substantially parallel alternate layers of conductive and non-conductive cured elastomer, the linear dimension of the strip along a direction perpendicular to the layers and passing therethrough being at least several times the largest linear dimension of any single layer.

11. The strip of Claim 10 wherein the elastomers are silicones.

12. The strip of Claim 10 wherein the layers are between .0003 and .125 inches thick.

13. The strip of Claim 10 wherein the layers are between .001 and .040 inches thick.

14. The strip of Claim 10 wherein the number of layers in the strip is greater than the number of conductors in any said set of conductors

15. The strip of Claim 10 wherein the layers are approximately perpendicular to the surfaces of said sets of conductors.

16. A layered strip connector for electrically connecting sets of spaced electrical conductors comprising alternate layers of conductive and non-conductive cured elastomer, the layers having a thickness between .0003 and .125 inches, the linear dimension of the connector along a direction perpendicular to the layers and passing therethrough being at least several times the largest linear dimension of any single layer.

17. The layered strip connector of Claim 16 wherein the layers have a thickness between .001 and .040 inches.

18. The layered strip connector of Claim 16 wherein the layers are approximately perpendicular to the longitudinal surfaces of the strip.

19. An electrical connector for connecting at least two sets of spaced electrical conductors, the electrical connector comprising a plurality of elements, each element comprising a strip of substantially parallel alternate layers of electrically conductive and non-conductive cured elastomer, the linear dimension of each strip along a direction perpendicular to the layers and passing therethrough being at least several times the largest linear dimension of any single layer.

20. The electrical connector of Claim 19 further comprising means for retaining at least two of said elements in substantially fixed relation one to another.

21. The electrical connector of Claim 20 wherein said means is an elastomer cured to the said at least two elements.

22. Two sets of spaced electrical conductors and an electrical connector for connecting the two sets of spaced electrical conductors, the two sets of electrical conductors proximately positioned on opposite sides of the electrical connector, each set comprising a plurality of closely spaced conductors positionally fixed with respect to each other, the electrical connector comprising alternate layers of conductive and non-conductive cured elastomer, the linear dimension of the electrical connector along a direction perpendicular to the layers and passing there-through being at least several times the largest linear dimension of any single layer, the number of layers of conductive elastomer being at least equal to the number of electrical conductors in either of the two sets of spaced electrical conductors.

23. The combination of Claim 22 wherein each layer of the electrical connector is between .001 and .040 inches thick and the linear dimension of the connector along a direction perpendicular to the layers and passing therethrough is at least 20 times the thickness of any single layer.