DE3512237A1 - MULTILAYER FLEXIBLE CIRCUIT ARRANGEMENT WITH CONNECTING DEVICES BETWEEN THE LAYERS - Google Patents

Description

ROGERS CORPORATION, Main Street, Rogers, Connecticut United States of America

Multi-layer flexible circuit arrangement with interconnection devices between the layers

The invention relates to connection devices between electrical circuits. In particular, the invention relates to multilayer flexible circuit assemblies with connecting devices between the layers. The circuits consist of circuit patterns or Conductor patterns on insulating circuit carriers.

Multi-layer flexible circuit arrangements of known type are sometimes produced using polymer thick film technology. These circuit arrangements contain plates made of flexible polymer as a carrier material with arranged thereon Ladders. The insulating substrate material can, for example a polyester plastic, such as the plastic available under the name "Mylar" or another be known insulating plastic and the conductive pattern on it can be through conductive paints or pastes or by copper or by other conductor material, which in connection with flexible circuits and Switch membranes is used. It is often desirable to have two layers of flexible circuitry Circuits that are facing each other to connect.

There are currently three preferred methods of making such compounds. One procedure provides to apply an appropriately adapted insulating material covering over the conductor pattern and then a conductive paint or Paste to use to close the connection between the two conductor layers, adding in certain places the insulating material is bridged. According to a second method the conductor patterns are separated from each other by an insulating layer and the connections are made by that through-holes through the insulating layer at the appropriate points where the connection is made to be plated. According to a third method, the conductor patterns are again replaced by a non-conductive, insulating layer with the exception of those areas separated from each other in which the connections should be produced. These connections are then formed by metallic crimping elements, which are through both layers of the circuit extend through and the conductor patterns which are to be connected together in Keep in touch.

These known methods lead to reliability problems either due to migration examinations through the appropriately shaped insulating coverings and / or due to defects in the conductor surface in the plated through holes and / or due to poor crimp connections. In addition, the known methods make expensive materials necessary and / or require complex ones Procedural steps.

There is therefore a need for a permanent, reliable and relatively inexpensive way of connecting in circuit arrangements of the type mentioned above.

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Thus, the invention has for its object to provide a multilayer flexible circuit having connection \ devices between the layers to design that the compound is easy and inexpensive to manufacture and has a high reliability.

This aim is given by the claims in the appended claim 1 Features achieved. In detail a more-; layered circuit arrangement designed so that it has a ; first circuit carrier layer with at least one first; Conductor pattern on it, as well as a second circuit carrier ; layer with at least a second conductor pattern thereon. The two ladder patterns face each other and each have an enlarged connection area of a predetermined shape at each opposite one another , Places where the connection between the two conductor patterns is made by ultrasonic welding.

As already mentioned, the connection areas have a special shape so that they are reliable and durable Enable contact. The resulting multi-layer flexible connector provided with the connector ! Circuitry is reliable in use and relatively inexpensive to manufacture.

It has been shown that the special connection lines : sample of the improved reliability and durability contribute.

In the following, exemplary embodiments are referred to explained in more detail on the drawing, the same reference numerals being used for corresponding parts : are. They represent:

j Fig. 1 is a schematic exploded view of a multilayer circuit arrangement of the type specified here,

Fig. 2 is a schematic exploded view of a multilayer circuit arrangement according to a other embodiment,

3 is a side view of the multilayer circuit arrangement according to Figure 2,

4A shows specific shapes of the conductor pattern in the up to 4E area of the connections for circuit arrangements of the type specified here,

Fig. 5 is a plan view of a multilayer circuit arrangement formed by folding with a upper circuit layer and a lower circuit layer, the layers having a Patterns of connections are interconnected in the manner specified here,

FIG. 5A shows a partial side view of the circuit according to FIG. 5,

FIG. 5B shows an end view of the circuit arrangement according to FIG Figure 5 with reference to those shown in this figure Position seen from the right side and ■

FIG. 5C shows an enlarged section of the connection area of the circuit arrangement according to FIG Fig. 5.

Reference is now made first to FIG. The exploded view shows a multilayer circuit arrangement 10. This contains a lower circuit carrier sheet 12, an upper circuit carrier sheet 14 and a interposed insulating and spacing Serving sheet 16. The lower circuit carrier sheet 12 is provided with conductor patterns 18 and 20 facing upward

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the top, which in connection areas 22 and 24 ends. A further conductor track 26 is on the circuit carrier sheet 12 only for the purposes of explanation shown, which is located between the conductor patterns or conductor tracks 18 and 20. The presence of the Conductor 26 makes it impossible in any case, the conductor tracks or conductor patterns 18 and 20 directly to connect on the circuit carrier sheet 12 with each other. So if the conductor tracks 18 and 20 verj together are bound, the connecting device must be connected to the upper circuit carrier sheet 14 run.

The downward facing surface of the upper circuit carrier sheet 14, namely the area which the

. Circuit carrier sheet 12 is facing, carries a conductor pattern 28 with connecting areas 30 and 32, which each

\ Weils aligned on top of the circuit carrier sheet 12 with the corresponding connecting portions 22 and 24th The conductor track 28 is shown in FIG. 1 as a broken line to indicate that it is located on the underside of the circuit carrier sheet 14. Next is

j the insulating, spacing layer 16 [provided with openings 34 and 36, which are also marked with ^! Connection areas 22 and 30 or 24 and 32 of the circuit board sheets 12 and 14 are in alignment.

: In order to use the multilayer circuit arrangement of the

ι the given type of assembly, the circuit carrier ! sheets 12 and 14 and the insulating separating layer 16 superimposed in alignment, as shown in Figure 1, with the circuit patterns facing each other • and are kept separate from the insulating layer. When the alignment is carried out, the connection area is in place : 22 opposite the connection area 30 via the opening 34 and the connection area 24 is aligned with the connection area 32 across the opening 36.

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The circuit sheets thus become a circuit arrangement stacked one on top of the other, with the insulating layer 16 between the circuit carrier sheets 12 and 14 comes to rest. The arrangement of the three layers can be done by glue, which is attached at certain points will be held together.

The electrical connection between the connection areas 22 and 30 and between the connection areas 24 and 32 is made by ultrasonic welding of the mutually aligned connection areas through the respective Openings of the insulating layer 16 made therethrough. The resulting circuit arrangement is therefore multilayered and has interconnected circuit areas, the connections being permanent, reliable and proportionate are cheap.

The present connection device and the Process for making such connections gives the designer considerable freedom in designing how this was not previously known in the field of multilayer circuit arrangements with connecting devices was. The location and arrangement of the connection points can can be selected and changed arbitrarily as needed in the construction without affecting other construction features or complications arise, such as this with known connection systems is to be feared, for example at Use of plated holes and adapted conductor coverings. The type specified here is also suitable Way of connection especially good for the construction of High reliability connection devices. In Figures 4A to 4E are various, particularly useful Shapes of the connection areas and the formation of the connections reproduced.

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Figures 2 and 3 show the application of those specified here Connection construction on the connection of circuit carrier layers of the type in which previously Crimp connections were typically used. at the AusführungsfoxTn according to Figures 2 and 3 has a multilayer circuit arrangement 50 a lower circuit carrier sheet 52, an upper Schaltungsstx "backing sheet 54 and an insulating spacer layer 56. The lower circuit carrier sheet 52 is with conductor tracks 58 and the upper circuit carrier sheet 54 carries conductor tracks 60. The interconnected Circuit parts can be, for example, the connection lugs or connection lugs of flexible circuits. As can best be seen from Figure 3, the insulating intermediate layer 56 ends shortly before the end of the circuit carrier sheet 52, so that the conductor tracks 58 and 60 at corresponding locations are exposed opposite one another. It is well known that in such a case Expensive crimp connectors are used to secure the circuit carrier sheets 52 and 54 in the areas where the conductor tracks 58 and 60 are opposite to connect to each other, so that an electrical contact between the conductor tracks on the two circuit carrier sheets comes about. With the circuit arrangement proposed here be facing each other and Exposed conductor tracks are connected to one another by ultrasonic welding to obtain power or signals from a To be able to transfer circuit carrier web to the other circuit carrier web, with expensive Krip connector are not used and a reliable, faultless connection is established.

It should be noted that the circuit arrangement specified here as an important feature more than just that Connection by ultrasonic welding included. Another important aspect is the special training

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the connection areas at or near the welding point. If the ultrasonic welding is carried out, must care must be taken that the weld does not affect the circuit functions, for example by Change in electrical resistance. To this Purposes are the conductor tracks, in whose area the connection is to be made, in the form in designed in a special way. As already mentioned, FIGS. 4A to 4E show various modifications of the circuit traces. In the drawings mentioned, the conductor track 70 is at the connection area 72, in which the ultrasonic weld 74 is to be arranged, widens vex ". It goes without saying that both conductor tracks or conductor patterns which are to be connected to one another, for example the lower and upper conductor tracks 18 and 20 according to FIG. 1 or the lower and upper conductor tracks 58 and 60 according to FIG. 3 a special one and are given the same shape in the connection areas.

While the widening of the joint areas can be done in a number of ways, such as this is shown in Figures 4A to 4E, for example, is the basic design concept in the widening the connection areas that not adversely affect the resistance or other electrical properties of the relevant Conductor tracks, which are to be connected to one another, is changed by the connection.

FIGS. 5 to 5C show a circuit arrangement 80 formed by folding, such as is used, for example, for manufacture more flexible keyboards is used. A lower circuit carrier layer 82 and an upper circuit carrier layer are connected to one another by ultrasonic welding in the manner specified here. The lower circuit carrier layer 82 is with conductor tracks or conductor pattern

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provided, which are located on the upward-facing surface and the upper circuit _{carrier layer 84 carries:} conductor tracks or conductor pattern 88 on their downward-facing surface. To simplify the illustration, the traces are shown only in the end region, where the compounds are to be prepared, but it is understood: floating, that '<areas of the Leitex-tracks in the form of each desired conductor pattern also on the other by area of the circuit carrier tiers extend. The top and bottom circuit carrier layers are ^; separated from one another by an insulating intermediate layer 90, but with the exception of an area in which connections are to be made by ultrasonic welding. However, it is also possible to provide openings in the insulating layer 90 at those points where the ultrasonic welds are to be made.

As can best be seen from FIG. 5, the conductor tracks are 86 and 88 widened at 92 and are in this place! the widening by means of an ultrasonic weld 94 with one another tied together. In this way, a power or a signal can be transferred from a conductor track 86 to an associated one Conductor 88 are transferred.

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Claims (8)

Claims 1. Multi-layer, in particular flexible, circuit arrangement (10, 50, 80) with a connecting device between the Layers, wherein a first circuit carrier layer (12 or 52 or 82) with at least one first conductor pattern (18, 20, 26 or 58 or 8.6) and a second circuit carrier layer (14 or 54 or 84) are provided with at least one second conductor pattern (28 or 60 or 88) and the Conductor patterns are facing each other, characterized in that the conductor patterns (18, 20, 26; 28 or 58; 60 or 86; 88) of the two circuit carrier layers (.12; 14 or 52; 54 or 82; 84) at opposite points with widened Connection areas (22, 24 or 72 or 92) are provided and connected to one another at the location of these widespread connection areas by ultrasonic welding are . 2. Circuit arrangement according to claim 1, characterized in that that the connection areas (22, 24 or 74 or 92) are designed so that by making the connection the electrical properties of the circuit pattern or conductor pattern are not changed. 3. Circuit arrangement according to claim 1 or 2, characterized in that that the enlarged connection areas (22, 24 or 74 or 92) are designed so that the electrical Vex bond through between the circuit carrier layers Ultrasonic welding is produced without changing the electrical resistance of the conductor tracks. 4. Circuit arrangement according to one of claims 1 to 3, characterized characterized in that the widened connection areas is formed by widening the conductor tracks. 5. Circuit arrangement according to claim 4, characterized in that the widened connection areas (72) are rectangular. 6. circuit arrangement according to claim 4, characterized in that that the widened connecting areas (72) are arcuate. 7. Circuit arrangement according to claim 4, characterized in that the widened connection areas (72) are circular. 8. Circuit arrangement according to one of claims 1 to 7, characterized by an insulating, spacing serving layer (16 or 56 or 90) between the first and the second circuit carrier layer for separation of these layers with the exception of those areas in which the connection areas are located.