CH646280A5 - METHOD FOR PRODUCING INTERMEDIATE PIECES. - Google Patents

Description

The present invention relates to a method for producing connecting intermediate pieces from an electrically conductive rubber-like elastomer, which are used to connect electronic circuits by means of a press contact.

According to the state of the art, the mentioned connecting adapters of the so-called press contact type are produced from electrically conductive, rubber-like elastomer by means of the method explained below. There are 30 e.g. several layers of electrically conductive and insulating rubber-like elastomers are placed alternately on top of one another and connected to form an integrated laminate, which in turn is cut in planes perpendicular to the plane of the layer, which results in striped plates. These plates 35 and several layers of an electrically insulating, rubber-like elastomer are in turn placed alternately on top of one another and connected to form an integrated laminate which is cut again in planes perpendicular to the layer plane and to the longitudinal direction of the strips (cf. e.g. 40 Japanese patent publication 52-29 958 and U.S. Patent 3,982,320).

The procedure described is disadvantageous because it requires two layers and two cuts, which leads to increased manufacturing costs due to the complexity of the method 45.

It is therefore an object of the present invention to provide a new and improved manufacturing method for press-contact type connecting adapters made of rubber-like elastomer, which leads to high productivity without the above-described problems of the known methods.

According to the invention, this object is achieved in that a support layer is provided on one of its surfaces with protruding strips made of an electrically conductive material; a layer of uncured, electrically insulating, rubber-like elastomer is placed on the carrier layer on the surface provided with 55 strips; the backing layer and the uncured layer of rubber-like elastomer are joined by pressing, whereby the protruding strips of electrically conductive material sink into the uncured layer of rubber-like elastomer; the uncured rubber-like elastomer is cured, whereby the strips are adhesively bonded to the cured layer of rubber-like elastomer; the backing layer is separated from the hardened layer of rubber-like elastomer, so that the strips are transferred as an embedding to the hardened layer of rubber-like elastomer, and the hardened layer of rubber-like elastomer with the strips embedded therein in

Longitudinal axis of the strip is cut open substantially vertical planes.

An advantageous modification of the method according to the invention for the production of connecting intermediate pieces with contact points, which are arranged in rows and columns 5, consists in that a carrier layer is provided on one of its surfaces with strips of an electrically conductive material that emerge therefrom; a layer of uncured, electrically insulating, rubber-like i0 elastomer is placed on the carrier layer on the striped surface; the carrier layer and the layer of uncured, rubber-like elastomer are connected by pressing, whereby the protruding strips of electrically conductive material sink into the uncured layer of rubber-like elastomer; the uncured rubber-like elastomer is cured, whereby the strips have been adhesively bonded to the cured layer of rubber-like elastomer; the backing layer is separated from the hardened rubber-like elastomer layer; so that the strips are transferred as an embedding to the hardened layer of rubber-like elastomer; a plurality of hardened layers of rubber-like elastomer produced in this way, each of which has embedded strips, are superimposed in such a way that the strips run in the same direction in all layers; the hardened layers of rubber-like elastomer are connected to form a laminated body, and the laminated body is cut open in planes which are essentially perpendicular to the longitudinal direction of the strips.

30th

Another advantageous possibility is that the rubber-like elastomeric layers are hardened after several layers with strips embedded therein have been placed on top of one another and these layers are joined to form an integrated layered body in one time under pressure.

Exemplary embodiments of the invention are described below with reference to the sacred drawing. In it show:

1 shows a perspective view of a carrier layer which is provided on one surface with a plurality of strips of an electrically conductive material emerging therefrom;

2 shows a representation of the successive steps in the method according to the invention, in a sectional view,

wherein, '5

a) a sectional view of the carrier layer with a plurality of strips emerging therefrom on one of its surfaces;

b) a sectional view of the carrier layer, the strips emerging therefrom being covered with a layer of uncured, electrically conductive rubber-like elastomer; 50

c) a sectional view of the carrier layer and the uncured rubber-like layer in the connected state, the stripes protruding from the carrier layer having sunk into the uncured rubber-like layer, and d) a sectional view of the carrier layer when detached from the hardened rubber-like layer with the strips of embedded therein show electrically conductive material;

Fig. 3 is a perspective view of the support layer with the stripes protruding therefrom and the layer of the uncured rubber-like elastomer, which is connected thereto in accordance with 60 Fig. 2 (c);

Fig. 4 is a perspective view of a finished connecting adapter with contact elements in a single row;

Fig. 5 is a perspective view of an intermediate connector that is similar to that of Fig. 4 but with an insulating layer;

Fig. 6 is a perspective view of an integrated

55

646 280

Blocks made by superimposing several layers with strips, and

Fig. 7 is a perspective view of a finished connecting intermediate piece with contact elements which are arranged in rows and columns.

As can be seen from FIG. 1, a carrier layer 1 is first provided on one of its surfaces with a plurality of strips 2 of an electrically conductive material emerging therefrom. Various types of films or plates are suitable for producing the carrier layer 1, provided that they have sufficient mechanical strength, including films made from plastics such as polyethylene terephthalate, polyethylene, polypropylene, polystyrene, polyimide resin, polyamide resin and the like, from regenerated cellulose and cellulose derivatives such as cellophane, nitrocellulose, cellulose acetate and the like, and metal foils made of aluminum or copper. The thickness of the carrier layer 1 is only important insofar as the dimensional stability of the carrier layer 1 is ensured.

A commercially available electrically conductive coating compound or electrically conductive paint, which is used as such, can be used as the electrically conductive material for forming the protruding strips 2. However, it is advantageous to manufacture the electrically conductive material by evenly distributing a sufficient amount of a powder of conductive material such as coal, graphite, metals and alloys, metal carbides and the like in a polymer matrix which, after curing, has a rubber-like elasticity, e.g. certain types of silicone resins and silicone rubber, polyurethane polymers and certain types of thermoplastic resins.

The method for attaching the protruding strips 2 to the surface of the carrier layer 1 is known. Conventional printing techniques such as screen printing, gravure printing and offset printing can be used if the electrically conductive material has a consistency which corresponds approximately to the printing color. The protruding strips 2, which are pressed, e.g. Screen printing, are then hardened, e.g. by heating.

It is necessary that the protruding stripes are applied to the carrier layer 1 with a sufficiently high dimensional accuracy. The distance P of the strips 2 and the width W and the height H of each strip 2 should be determined in accordance with the dimensions of the circuit boards with which the connecting adapter is brought into contact. The distance P e.g. moves in a range from 0.1 to 6 mm, the width W from 0.05 to 3 mm and the height H from 0.01 to 0.6 mm. The screen printing process is particularly suitable if protruding strips 2 with a relatively large height H are desired. On the other hand, finer strips 2 can advantageously be applied by means of the so-called photo process, a light-curing, electrically conductive coating composition being used, by means of which the carrier layer 1 is initially coated uniformly, after which exposure in strips is carried out in order to cause the composition to be light-cured at the exposed areas and the uncured portion is removed by washing with an organic solvent. In any case, the connection of the carrier layer 1 with the electrically conductive material is of importance for the formation of the protruding strips, since the adhesion between the carrier layer 1 and the hardened strip material must not be excessively large in order to transfer the hardened strips 2 in a subsequent step into the rubbery elastomer layer.

In FIG. 2, which shows the successive steps of the method according to the invention in sectional views, FIG. 2 (a) shows the carrier layer with the resultant

646 280 4

tendency strip 2. This arrangement is covered on the side with the strips 2 with a layer of uncured, electrically insulating rubber-like elastomer 3, as can be seen in FIG. 2 (b). Various types of synthetic rubber and 5 specific types of plastic resins are used as the rubber-like elastomer for the layer 3, which have a rubber-like elasticity after hardening. Some examples of such rubber-like polymers are: polyester, polyurethane, polybutadiene, polyisoprene rubbers, silicone rubbers, styrene-butadiene rubbers, polychloroprene rubbers and the like. If desired, the rubber-like elastomer for layer 3 can expand into a foamed body at the same time as it is hardened, so that the hardened layer 3 acquires an elasticity which is suitable for use as the base material of a connecting adapter, in which a very small compressive force is sufficient to establish a reliable connection. The layer 3 foaming technique is particularly advantageous when the connector adapter is to be used with certain miniaturized electronic instruments, such as very thin calculators, where no great compressive force can be applied to the connector adapter between the circuit board terminals.

The foaming process is known per se in that the uncured rubbery elastomer is given a foaming agent such as e.g. N, N'-dinethyl-N, N'-dinitrosoterepthalamide, N, N'-di-nitrosopentamethylenetetramine, azodicarbonamide, azobisisobutyronitrile, benzenesulfonylhydrazine or the like is admixed. 30th

The uncured, rubbery elastomer layer 3 is made by conventional methods such as e.g. Layering (sheeting) or distilling out (topping). and the thickness of the layer 3 is chosen according to the desired dimensions of the finished connecting adapter 35.

Thereafter, the backing layer 1 and the uncured elastomer layer 3 are bonded together as shown in Fig. 2 (c), e.g. by pressing by means of rollers or by means of two press plates, between which the carrier layer 1 and 40 and the uncured layer 3 lying thereon are clamped. Because of the plasticity of the uncured layer 3, the protruding stripes on the carrier layer 1 sink into the uncured layer 3 by this pressing and are embedded therein, as shown in FIG. 2 (c). It is necessary to lend the electrically conductive material which forms the protruding strips 2 to a sufficient degree of strength by being hardened beforehand so that the cross-sectional shape of each strip 3 is not impaired by the pressing.

If sufficient strength cannot be achieved even by hardening because of the high proportion of electrically conductive fillers in the electrically conductive material, auxiliary reinforcement of the protruding strips 2 is achieved by using a flowable coating connection, e.g. a silicone rubber compound curing at room temperature, a cover layer is applied before the uncured layer 3 is placed thereon.

The next step consists in curing the uncured, rubber-like elastomer layer 3 lying on the carrier layer 1 with the strips 2 embedded therein. The curing is normally achieved by heating, and the course of this heat treatment depends on the rubber-like elastomer used. It is necessary,

that this heating creates a strong adhesive bond between the strips 2 and the hardened, rubber-like elastomer layer 3. Fig. 3 is a perspective

50

55

65

View of a hardened layer 3 produced in this way on the carrier layer 1.

Thereafter, the hardened rubber-like layer 3 and the base layer 1 are separated from each other by peeling as shown in Fig. 2 (d). At this moment, the protruding strips 2 are transferred to the hardened rubber-like layer 3 by being embedded therein. It is a necessary requirement that the connection between the carrier layer 1 and the protruding strips and between the carrier layer 1 and the hardened rubber-like layer 3 is not too strong, so that a smooth detachment of the carrier layer 1 and a transfer of the strips 2 are ensured.

The cured, rubber-like layer 3, when it is freed from the carrier layer 1, together with the strips 2 embedded therein, is cut into pieces in a plane substantially perpendicular to the longitudinal direction of the strips 2, which are used as finished connecting intermediate pieces, as in FIG. 4 shown, used. The thickness of the individual pieces of course depends on the particular use.

It is possible to provide the hardened rubber-like layer 3 with the strips 2 embedded therein with an insulating layer 4 made of an electrically insulating rubber-like elastomer, which is preferably of the same type as the layer 3, so that each strip 2 is only on opposite sides Cut surfaces that result from the cutting open surfaces, as shown in Fig. 5, according to the special use of the connecting intermediate piece.

In the embodiment of the method according to the invention described above, the finished connecting intermediate piece has a plurality of contact elements arranged exclusively in a row, i.e. Segments of strips 2 made of electrically conductive material, as can be seen from FIGS. 4 and 5. If a connecting adapter with contact elements in a row and column arrangement is desired, the described method is modified somewhat. In this way, several hardened, rubber-like layers 3, each of which has embedded strips 2, are placed on top of one another and respectively connected with the front and back using a suitable adhesive, so that the strips 2 of all layers 3 run in the same direction and an integrated block 6 is formed as shown in FIG. 6. The integrated block 6 in FIG. 6 is provided with a cover layer 5, so that the last surface on which the strips 2 are exposed is covered. The block 6 obtained in this way is then cut into planes which are substantially perpendicular to the longitudinal direction of the strips 2 and in most cases substantially perpendicular to the plane of the layers, resulting in the plate-shaped connecting adapter of Fig. 7, in which the contact elements , ie the segments of strips 2 are arranged in rows and columns.

It is of course also possible to provide the hardened rubber-like layers 3 with strips 2 of electrically conductive material, which have different distances P, widths W and heights H, so that the finished plate-shaped connecting intermediate piece has contact elements with an irregular arrangement, as required.

It is also possible, in the production of the above-mentioned block, to free the rubber-like elastomer layer 3 with the strips 2 of FIG. 2 (c) embedded therein by detaching them from the carrier layer 1 before the curing is carried out and several so obtained Unhardened, rubber-like elastomer layers 3 with strips 2 embedded therein, in the same way as the hardened layers 3, to be placed on top of one another and subsequently simultaneously bonded under heat and pressure and hardened into one

tegrated block 6. In this process, a strong connection is achieved without adhesives.

It can be seen from the above description that the method according to the invention provides an extremely efficient means of producing connecting intermediate pieces from rubber-like elastomer in a sequence of simplified steps. Furthermore, connecting intermediate pieces, which are produced according to the inventive method, can be arranged at a very small distance of 1 mm or less

5,646,280

Contact elements and be manufactured with high precision at very low cost. The plate-shaped connecting adapter according to FIG. 7 can, for example, spread between two switching units and cover their entire surface, punched-out, empty areas in the form of a hole or a recess corresponding to special locations on the switching units where the intermediate connecting adapter would interfere.

C.

1 sheet of drawings

Claims (3)

646280 PATENT CLAIMS 1. A process for the production of intermediate connecting pieces for press contacts from a rubber-like elastomer, characterized in that a) a carrier layer is provided on one of its surfaces with strips of an electrically conductive material emerging therefrom, b) a layer of uncured, electrically insulating, rubber-like elastomer is placed on the carrier layer on the striped surface, c) the carrier layer and the uncured layer of rubber-like elastomer are connected by pressing, as a result of which the protruding strips of electrically conductive material sink into the uncured layer of rubber-like elastomer, d) the uncured, rubber-like elastomer is cured, whereby the strips are adhesively bonded to the cured layer of rubber-like elastomer, e) the carrier layer is separated from the hardened layer of rubber-like elastomer, so that the strips are transferred as an embedding to the hardened layer of rubber-like elastomer, and f) the hardened layer of rubber-like elastomer with the strip embedded therein in the longitudinal axis of the strip in essential vertical. Sliced layers. 2. A process for the production of connecting spacers for press contacts made of a rubber-like elastomer, characterized in that a) a carrier layer is provided on one of its surfaces with strips of an electrically conductive material emerging therefrom, b) a layer of uncured, electrically insulating, rubber-like elastomer is placed on the carrier layer on the surface provided with strips, c) the backing layer and the layer of uncured, rubber-like elastomer are connected by pressing, as a result of which the protruding strips of electrically conductive material sink into the uncured layer of rubber-like elastomer, d) the uncured, rubber-like elastomer is cured, whereby the strips are adhesively bonded to the cured layer of rubber-like elastomer, e) the carrier layer is separated from the hardened layer of rubber-like elastomer, so that the strips are transferred as an embedding to the hardened layer of rubber-like elastomer, f) several hardened layers of rubber-like elastomer produced in this way, each of which has embedded strips, are placed on top of one another such that the strips run in the same direction in all layers, g) the hardened layers of rubber-like elastomer are connected to form a laminated body and h) the laminated body is cut open in planes which are essentially perpendicular to the longitudinal direction of the strips. 3. A process for producing connecting spacers for press contacts from a rubber-like elastomer, characterized in that a) a carrier layer is provided on one of its surfaces with strips of an electrically conductive material that emerge therefrom, b) a layer of uncured, electrically insulating, rubber-like elastomer is placed on the carrier layer on the surface provided with strips, c) the carrier layer and the uncured layer of rubber-like elastomer are connected by pressing, as a result of which the protruding strips of electrically conductive material sink into the uncured layer of rubber-like elastomer and are connected to it, d) the carrier layer is separated from the uncured layer of rubber-like elastomer with the strips embedded therein, e) several of the uncured layers of rubber-like elastomer, each of which has strips embedded therein, are placed one on top of the other in such a way that the strips of all the layers run in the same direction, f) the unhardened layers of rubber-like elastomer placed one on top of the other are joined and hardened to form a laminated body, and g) the laminated body is cut open in planes which are essentially perpendicular to the longitudinal direction of the strips.