DE1490391A1 - Process for the production of printed electrical circuits - Google Patents

Description

Process for the production of printed electrical

Circuits

The invention relates to the production of so-called printed electrical circuits, in which, to a To define circuit shape, the flat conductor tracks closely with one and / or the other insulating surface a carrier are connected. The term "printing of circuits" is usually used to describe all processes the reproduction of such products of configurations of predetermined conductor tracks on an insulating surface.

The invention relates to a method for production these products, which allow economical production on an industrial scale, and products of higher quality Quality delivers.

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The method consists essentially in the form of raised portions in a conductive layer, which limitation _ zen the outline of the conductor paths in the finished circuit in the mounting at least one such molded Sc / iicht on an insulating support and in the removal of at least the raised Parts to get the desired configuration in the finished product. To produce a double-sided circuit, two preformed layers are fastened simultaneously on an insulating carrier, which then serves as an intermediate piece, the relative positions of the pollen to one another for this fastening being marked with marks. The connections from one side to the other are formed either before or after the raised parts are removed in additional process steps, with recesses for such connections being able to be provided in the insulator as required. The raised parts can be arranged in such a way that they encompass all spaces between the conductor tracks, if the circuit is in which the conductor tracks do not have to be adjacent to one another. After removing the raised parts, only the circuit tracks remain on the carrier. The raised parts can instead be arranged in another embodiment in such a way that they only represent elevations along the edges of the conductor tracks, and in this Pail

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there will still be "dead" areas on the insulator which are superfluous for the circuit. In most of them Cases you can leave these dead spots. However, if their presence is not desirable, they will be they are taken away in a further stage, for example on chemical \ fege.

The relief-like formation of the conductive layers is taäss the first process stage of the process according to the invention can be done either by mechanical embossing of the conductive foils using matrices or by deposition conductive layers on the reverse projecting relief surfaces of transfer matrices, i.e. of matrices on the surface of which the conductor deposits do not adhere well. Of course that would also exist Possibility of double-sided engraving of the conductive foils. However, this procedure would become more complicated and the product will be difficult to obtain. In addition, with this latter method the requirement of hollowed out matrices for the following stage of fastening the relief-like layers on their insulating pads are not avoided. This second stage of the process is preferably the application a molded layer on the insulating surface covered with a thermosetting or polymerizable, only in

909607/0933 'Gel form

GeIforη present resin is coated, whereby the Holds raised parts of this layer in place using a die and then applies pressure and heat to the resin to harden and thus create an intimate connection between the layer and the substrate. When the shift was modulated on a transfer matrix, it will detach itself from the matrix when it is withdrawn, because it adheres firmly to the insulating support and little to the surface of this die. In addition, the insulating support preferably consist of fiber layers, which are impregnated with a resin of the type mentioned above are, which are in the press, so that during this second stage at the same time Base is formed. The raised parts are preferably removed by simple mechanical abrasion, ZoB. by grinding. The raised parts could of course also be removed chemically. This would however, an additional stage of the process is required make, namely the deposition of an acid-resistant protective coating on the insulator pad contained recessed parts of the conductive relief layer.

In the case of double-sided printed circuits, the connections between the conductor tracks of the two surfaces

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be produced by the known method working with metallized through-holes, the production the holes and the deposition of metal in the holes either before or after removal of the raised Parts takes place. Instead of metallizing the through holes, you can insert conductive rivets like them are also known in the art to manufacture the bearers of the circuit, metallic rails Provide that extend beyond the insulating pad, at least on small tongues on previously determined Make these small tongues cut off if necessary after attaching the layers to the backing can be. The small tongues in question then only have to be welded in pairs, for example by spot welding. To establish the connections between the Edges of distant conductor tracks can be used instead of the process that is metallized or otherwise equipped Holes are known to provide recesses in the insulating base during the fastening stage, then deform the parts of the conductor tracks on both sides at the points of these recesses and push them through connect electrical spot welding. It is also possible to modulate the relief of the conductor layers in such a way that

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that these parts of the conductor tracks are deformed in such a way that they are deformed when the rails are connected to the base come into contact with each other.

The original invention is described below with reference to the Drawing described.

Pig. 1A is a partial view showing in section Execution method of the first process stage, i.e. the formation of a conductive foil by embossing using a die, the foil having the in Fig. 2Λ shown relief-like shape is given.

Fig. 5A shows the stage of attachment of the two foils formed in this way on an insulating base for making a double-sided printed circuit and the

Fig. 4A shows in section aas obtained in this second stage Product.

Fig. 5A then shows in section the circuit that one obtained after removing the raised parts of the product shown in Fig. 4A.

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Figures 1B to 5B show the same steps in one other execution.

FIG. 6 shows in section a product which can be obtained from the product shown in FIG can be produced by conductive surfaces that are regarded as superfluous and harmful.

7 is a partial view and shows, in section, another embodiment of the first process stage, namely the deformation of a conductive layer on a "transfer die".

FIG. B, a partial view, then shows in section the second process stage, and that at this stage product received is on average in I'ig. 9 shown.

10 shows the finished product after the raised parts have been removed.

FIG. 11, which consists of three schematic drawings, a), b) and c), shows an embodiment of the invention for production of the connections in a double-sided printed outline.

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Fig. 12 shows in two schematic drawings, a) and b), a procedure for the production of interfacial connections by hole metallization.

13 shows in section a special embodiment for the production of interfacial connections in a circuit according to the invention.

In Fig. 1A you can see a flat and thin conductive film 1 in exactly the same thickness as it is for the conductor tracks of the finished Circuit is desired. The film lies on a base 3 made of rubber or a similar material. A die 2 lies on the film 1. This die is provided with cavities, as shown in FIG. the Arrangement is placed in a press, not shown. After pressing, the film 1 is deformed, just like it in Fig. 2A is shown and has G-rate 6, which the Limit the outline of the conductor tracks in the desired circuit. This film could also be used with the 'reversal die' 2A is a view of the then "inverted" film.

The embodiment presented by way of example relates to a double-sided circuit. Figure 3A shows two foils 1 already formed in the relief-like shape

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and 11, which are attached to "both sides of an insulator ö consisting, for example, of layers of fibers impregnated with a resin that is only in gel form. Each slide is büw through a mold 2. 12 held, which can be the same matrices that for the previous training used for foils or similar matrices. When applying pressure and heat, using the press is not specifically shown, the insulator ö is formed between the metal foils, the deformation of which occurs the matrices are prevented and at the same time polymerisation or hardening of the insulator occurs, wherein the foils are attached to an insulating support forming an intermediate piece. The thereby obtained The product is shown in the slice of FIG. 4A.

In order to separate the conductive parts from one another, it is then sufficient to remove the ridges of the metal foils which are designed in relief to remove, which is preferably done by mechanical abrasion, e.g. by grinding. After the removal of the Burrs 6, the double-sided printed circuit then has the shape shown in FIG. 5A. The conductor tracks 1 on one surface and the conductor tracks 11 on the other Area are now separated by narrow spaces 13 in which the insulator is exposed and exactly in one Level with the level of the conductive surfaces.

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With certain circuit forms and the ladder balines not absolutely adjoining and dead, i.e. inactive conductive surfaces remain in the clement. In most In cases, the presence of these dead areas is not disruptive. It may still be desirable to remove them. In this case, these dead areas are removed in an additional process stage, either simply on mechanical yegs by scraping or chasing, or by chemical means, by allowing acid to act on these conductive surfaces after thinning them beforehand acid-resistant coating deposited on the actual circuit traces. the Fig. B shows the element of FIG. 5A, in which the interfering conductive surfaces have been removed, the Wells 15 received.

In the special cases where the dead areas are not desired in the final product, to avoid such an additional measure is a procedure, as shown in Figures 1B to 5B preferable. In this process, all process stages and intermediate products of the implementation of the process of the invention according to FIGS. 1A to 5A are reproduced, but the flat die 2 in the first process stage, FIG. 1B, is formed with such depressions as

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them in ί? are shown which depending on. If required, occupy the entire area that should be exposed on the finished product between the conductor tracks. Such surfaces will therefore appear in the form of relief-like elevations 7, FIG. 2B. After attachment to the base, FIGS. 5B and 4B, these driven surfaces as well as the burrs 6 will be present and they will be removed at the same time as the burrs, resulting in the circuit shown in FIG adjoining conductor tracks has recesses 14 in which the insulating substrate is also in one plane with the remaining conductive surfaces.

Instead of starting with conductive foils, you can also follow them up Another way of working is to use a transfer method: a die is used in the cavities according to the desired relief 22, Fig. 7, cut are, and deposited on this, for example by electrolytic means, a conductive coating 2b, the adheres only very weakly to the die surface. For this purpose, the die does not consist of, for example oxidizing steel or brass and has a coating 24 made of chromium or a chromium alloy. The deposition takes place as long as there is a conductive one

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Layer 21 of the desired thickness has been obtained, which has ridges 26, which form the relief-like cavities correspond to the die.

Two such matrices provided with conductive layers are then placed on both sides of an insulating fiber layer 28 applied, which is impregnated with a present in gel form resin (Fig. 8). Me second die 32 carries 34 on its chromium or chromium alloy layer non-adhering the metallic layer 31 with its ridges 36. As before, these matrices are brought into suitable positions relative to one another with the aid of attached marks. When pressure and heat are applied, the fiber layers are attached to one another and the metallic layers on the insulating pad. Then the dies are removed. The firmly to the pad and little to it Conductive layers adhering to the matrices result in the product shown in section in FIG. y. The removal of the ridges by removal then leads to the printed circuit shown in FIG. 10, which gaps 23 and 33 between has the conductor tracks on the surface of the insulator.

Instead of the unshaped base, a preformed insulating varnish can also be used in the second process stage

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use and coat it with a resin in gel form. This gives an equivalent result, with the exception that the insulating surfaces are what the base body of the insulating substrate do not lie in the same plane as the conductive surfaces of the final product.

Each circuit produced according to the method of the invention can then optionally be provided with a protective covering v / ground, as is customary in the production of such circuits, for example with a coating of nickel or a nickel alloy.

The method described also enables the production of non-planar printed circuits, if necessary, just as easily as the production of flat printed circuits, since it is sufficient to start with the matrices Forming the metallic layers and foils to form the desired curved, curved, conical or cylindrical etc. shapes, regardless of whether a single or double sided circuit is to be made.

It should also be briefly stated how the connections between the conductor tracks in the double-sided circuits of the two opposite surfaces

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can. The production of such connections is already "known per se" and it is sufficient to indicate here how to proceed in practice in the production of the circuits according to the method of the invention.

The connections can be made on the edge by metallizing the edges of the finished product and then removing the superfluous metal parts by scraping or by chemical means. The connections can also be made, for example, by electrically welding small conductive tongues which are preformed in such a way that they protrude beyond the edges of the insulating intermediate part. For this purpose, a distance is provided on the insulator during the second process stage by keeping the dimensions of the metallic layers larger than those of the insulator so that they protrude beyond the insulator on the side surfaces of the circuit. Vie in Pig. 11, drawing a) from above and figure) b shown from the side, one small tongues, as in 52 and 53 can be represented, crop, which extend the conductive paths such as 50 and 51 on the surfaces of the interlayer insulating layer 58 addition and then the relevant tongues, for example, by electrical spot welding, drawing c), 3? ig. 11, unite.

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To make these connections, the small tongues on the conductive foils can be closed before they are formed a relief or preform them when using transfer matrices form in the process of tipping. If you haven't preformed them that way, you can do them before or after Cut away the raised parts and you can choose one or the other process stage. In any case the small tongues are then united by pure white whitening.

Drilling is used to produce the interfacial connections running transversely through the insulating interlayer Before or after the raised parts are removed, first holes, as shown in FIG. 5A, drawing a) of FIG. 12 and then sensitizes the inner walls of these holes using a known non-electrolytic isohen Method whereby the exposed parts of the isolator are protected if one takes this measure after the removal of the carries out raised parts. The circuit is then placed in a container containing an electrolyte, in which the deposition of an uninterrupted layer of metal on the interior walls providing the desired connections the holes 55, drawing b), and on the surface conductor tracks 56 and 57 takes place. The resulting thickening the conductor tracks can be used when choosing the thickness of the conductive

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Foils or the layers deposited on the transfer matrices are taken into account.

Another embodiment for making connections

fertilize is to provide recesses in the insulator 58 at the desired locations, as shown in Fig. 13, then the teiterbahnen to deform at these sites in order to bring them into contact with each, and as shown in 59, by electrically Punktsohweissen to connect with each other. The recesses can be obtained by pulling together the jaws of the electric welding device. According to another embodiment, the depressions in the formation of the layers and foils can be provided by a corresponding adaptation of the matrices to this process stage.

Claims

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Claims (12)

Claims 1) Procedures for the manufacture of printed electrical products Circuits, characterized in that at least a conductive sole is formed into a belief, the ridges of which are the outlines of the conductor tracks of the finished Limit product that at least one layer formed in this way on an insulating base is attached, and that the ridges of this conductive relief sur separating the conductor tracks in the circuit be removed, 2) Method according to claim 1, characterized in that that in the “next stage of the process, the formed layer held by means of a matrix to maintain the Porm on the surface of an insulating pad becomes what at least «a superficial Sohioht one only in gel form contains resin lying on the ground, and that the arrangement to harden the resin and ensure the intimate adhesion between the formed conductive surface and the substrate without deforming the burrs des Belief · heat and bridge is exposed. 3) Method according to claim 1, characterized in that daduroh A conductive film is used to form the conductive layer between 909807/0933 ORiGtNAL between a die with a negative relief and a Base made of hard rubber is brought, and that but Deformation of the film according to the hollow relief of the - die pressure is applied. 4) The method according to claim 1, characterized in that for forming the conductive layer one of the negative of the Beliefs the conductive layer corresponding die with a chromium-containing coating is made, whereupon one electrolytically the leather layer in the desired Dioke is deposited on this coating, to which it only weakly adheres, aqdass with the adjoining one Removal of the die the conductor base is firmly adhered to remains behind the insulating support. 5) The method according to claim 1, characterized in that in the second process stage, the pad from with a thermosetting and only available in gel form Resin-impregnated fibers is produced that the die containing the conductive layer on a surface this pad is placed, and that pressure and heat · are applied to make the pad rigid at the same time to shape and to ensure their intimate adherence to the conductive Sehloht. 909807/0933 BAD ORIG4NAL 6) Procedure naoh Anspruoh 1, daduroh characterized, dam In the third stage, the ridges of the relief-like conductor are mechanically removed. 7) Method according to claim 1, characterized in that Gate taking away the ridges of belief that need to be maintained Parts of an acid-resistant product are soaked over, and that the coating is not protected parts are treated with acid until the insulating surface is exposed. 8) Method naoh claim 1 «daduroh characterized that the dead conductive heights remaining in the first stage in the circuit in the third stage are also added to remove the ridges of the relief 9) Method naoh claim 1, characterized in that cur production of a double-sided circuit in the second stage the two molded conductive layers equilateral on opposite faces of one insulating support to be attached, and that in addition «steps to make the connections between the two are rarely provided in the circuit. 10) Method according to claim 9, characterized in that daduroh at these additional stages before attaching the 909807/0933 senior BADORiGJNAL. conductive layers are provided on the insulating support in these holes, and that the conductive layers are deformed at these locations so that that they come into positive contact with each other across these holes. 11) Method according to claim 10, characterized in that when forming the conductive layer in relief-like, The ridges separating the conductors also form a relief in the opposite direction, which the training of the Zwisohenfläohenverbindungen at least prepared, which in the second stage by penetrating the to holes prepared in the carrier for this purpose. 12) The method according to claim 10, characterized in that the contact points after or during the bringing together of the layers transversely through the holes of the insulator be connected by electrical radio connection under pressure 7/0933 BATH