WO2005109978A1

WO2005109978A1 - Releasable electrical contact of three-dimensional moulded interconnect devices

Info

Publication number: WO2005109978A1
Application number: PCT/EP2005/004887
Authority: WO
Inventors: Lorenz Berchtold; Joachim Neubert; Gerhard Nicklbauer; Wolfgang John; Werner Enser; Andreas Kunze; Claudius Schimpf
Original assignee: Tyco Electronics Pretema Gmbh & Co. Kg; Intedis Gmbh & Co. Kg; Odu Steckverbindungssysteme Gmbh & Co. Kg; I & T Innovation Technology Entwicklungs- Und Holding Ag; Friedrich-Alexander- Universität Erlangen-Nürnberg
Priority date: 2004-05-11
Filing date: 2005-05-04
Publication date: 2005-11-17
Also published as: DE102004023189B4; DE102004023189A1

Abstract

The present invention refers to a three-dimensional moulded interconnect device, a so-called 3D MID. In particular, the present invention refers to a 3D MID for attachment to a flexible flat cable. Further, the present invention refers to a corresponding method for detachably contacting a three-dimensional moulded interconnect device. In order to improve a 3D MID in a way that a particularly reliable and economic electric connection can be formed to a flexible flat cable, the circuit carrier comprises according to the present invention a pressing plate (114) for pressing at least one connection region (132) of the flexible flat conductor (112) onto at least one contact region (110). The flexible flat conductor (112) can be inserted at least partially between the pressing plate (114) and the substrate (110) and the contact region (110) comprises a convex bulge for contacting the connection region (132).

Description

RELEASABLE ELECTRICAL CONTACT OF THREE-DIMENSIONAL MOULDED INTERCONNECT DEVICES

The present invention relates to what is known as a 3D MID (three-dimensional moulded interconnect device). In particular, the present invention relates to an interconnect device of this type for releasable electrical contact with a flexible flat conductor. The present invention also relates to a corresponding method for the releasable electrical contacting of a three-dimensional moulded interconnect device. The ever more stringent demands that are placed on the safety, environmental compatibility and economic efficiency of modern mass-produced articles in the industrial and consumer goods market are difficult to meet with conventional mechanical and electrical systems. Presently, complex objectives are therefore increasingly achieved by using decentrally arranged mechatronic units, which integrate mechanical and electrical functions in a single module. 3D MID engineering provides the key to integrating electrical and mechanical functions in interconnect devices of any shape, in which metallic conductor tracks form a composite with a, usually thermoplastic, moulded part. Three-dimensional moulded interconnect devices of this type offer considerable potential for improving the efficiency of electrical and electronics production, and are generally more environmentally acceptable than conventional printed circuit boards. The structure of modern on-board wiring systems, for example in the car industry, has displayed a turn from previous central control devices toward decentrally arranged electronics modules and an associated marked increase in "on-site intelligence". The use of 3D MED technology offers enormous potential for integrating mechanical and electrical functions in an interconnect device and also for making optimal geometrical use of overall space. 3D MED technology is therefore increasingly being used in industry in the production of decentral mechatronic units. In the automotive industry, the on-board wiring forms the backbone of the divided systems, both for control currents and for power currents. The substantially increased size of the required wiring structures with respect to weight and assembly automation has tended to call for new approaches. In the car industry in particular, at least in many sectors, the round cables that were used in the past have frequently been replaced by laminated or extruded flat cable systems. The use of flexible flat conductor structures of this type in car wiring systems provides significant advantages over conventional cable harness structures in terms of weight reduction, utilisation of overall space, increase in integration density and cost reduction by automated assembly. Nevertheless, the electrically releasable connection of decentral MED modules to the on-board wiring structure on the basis of foil-insulated flat conductors is problematic, as known plug connector systems lead to higher costs as a result of plug and socket parts and relatively complex assembly processes. Moreover, a substantially larger overall space is required for previous solutions. In conjunction with the electrical connection of flexible flat conductors to conventional interconnect devices (printed circuit boards, PCBs), it is known to press the flexible flat conductor, using various pressing devices, onto corresponding contact regions of the printed circuit board. Contact designs of this type are known, for example, from US patent specifications US 5295838 and US 5730619, German Of enlegungsschriften DE 19832011 Al and DE 10028184 Al, and US patent specification US 3629787. However, these known contact systems are not easily transferable to the application of a three-dimensional moulded interconnect device, and they usually entail substantial production engineering costs. The object of the present invention is therefore to improve a three-dimensional moulded interconnect device of the aforementioned type such that an electrical connection, which may be produced in as reliable and cost-effective manner as possible, to a flexible flat conductor may be produced. This object is achieved by a three-dimensional moulded interconnect device having the features of claim 1 and by a method for the releasable electrical contacting of a three-dimensional moulded interconnect device having the steps of claim 22. Advantageous developments of the present invention are recited in a plurality of sub-claims. The present invention is based on the idea of providing a pressing plate for pressing the connection regions of the flexible flat conductor against contact regions on the substrate of the three-dimensional moulded interconnect device and of providing the contact region with a convex bulge. The flexible flat conductor is held at least partially between the pressing plate and the substrate. The pressing plate is preferably resilient in its construction, so that it forms a long-stroke spring for exerting the required contact force. On the one hand, this solution has the advantage that plug connections that are complex in their construction and assembly may be dispensed with. On the other hand, the electrical contact according to the invention allows a particularly reliable electrical contact to be produced, which contact may, however, easily be released if required. Assembly is simple, clear and economical to implement. Finally, the three-dimensional moulded interconnect device according to the invention allows the advantages both of 3D MED technology and of the flexible flat conductors to be fully utilised. A particularly effective possibility for fixing the resilient pressing plate to the substrate of the three-dimensional moulded interconnect device consists in the fact that it comprises at least one locking device, which cooperates with at least one associated locking recess on the substrate for mechanically fixing the pressing plate. Locking connections of this type may be produced easily and cost-effectively, are easy to assemble and may, if required, also be released again without difficulty. Alternatively, a locking recess that cooperates with an associated locking device of the substrate may also be provided in the pressing plate. These two solutions may be viewed as being of equal value, and which is preferable will depend on the respective design requirements. A combination of the above arrangements, i.e. locking recesses and locking devices such as, for example, locking hooks, both on the pressing plate and on the substrate, is also possible. According to an advantageous embodiment, the pressing plate may be configured as a bending beam, which is fixed on two sides, comprising a first and a second fixing region, as a result of which the necessary pressure in the contact region may be ensured in a particularly simple manner. If it is provided that the first fixing region is configured as a hinge-like connection, so the pressing plate, for producing the electrical contact between the contact region and the connection region, may be swivelled about an axis of rotation, a mechanical fixing of the pressing plate to the substrate may be attained that makes due with as few locking connections as possible and is particularly beneficial from the point of view of force distribution. In particular, the process of releasing the connection is simplified in an arrangement of this type. The use of the hinge-like connection also ensures a pre-positioning of the pressing plate with respect to the substrate, so assembly errors may be prevented during locking. In particular, if the pressing plate is already connected to the flexible flat conductor in a pre-assembly state, a solution in which the axis of rotation extends substantially transversely to a longitudinal axis of the flexible flat conductor is a highly beneficial variant from the point of view of assembly. However, the axis of rotation may also of course extend parallel to the longitudinal axis of the flexible flat conductor. Alternatively, however, the pressing plate may also be configured in the form of a slide, which is held in at least one lateral guide, for example a groove. In the embodiment of the pressing plate as a bending beam that is secured at both ends, the second fixing region may advantageously be formed by at least one locking hook, which, in the final assembled state, is locked to an associated locking recess in the substrate. The locking recess may of course also be provided on the locking plate, and the associated locking hook integrally formed on the substrate. In order to be able to secure the pressing plate to the flexible flat conductor in a simple manner, in a pre-assembled state, and also to arrange the flat conductor in as space-saving a manner as possible during assembly, the pressing plate may, according to an advantageous embodiment, be configured such that the flexible flat conductor may be deflected about the pressing plate substantially in the shape of a U. As positioning of the connection region that is as precise as possible is required for making electrical contact between the contact region of the substrate and the associated connection region of the flexible flat conductor, the pressing plate may comprise at least one guide projection, which cooperates with at least one corresponding guide opening in the flexible flat conductor. A connection region that is defined by an opening in the sheathing insulation of the flat conductor obviates the need to configure this opening in an unnecessarily large form. According to an advantageous embodiment, a holding device for mechanically fixing the flexible flat conductor to the pressing plate may be arranged on the pressing plate. This is particularly important if the pressing plate is to be connected to the flexible flat conductor in a pre-assembly state. The pressing plate may be held captive on the flexible flat conductor by means of a holding clip, for example, which at least partially encompasses the flexible flat conductor and the pressing plate. For compensation of production tolerances, and hence more reliable electrical contactivity of a large number of contact regions, the pressing plate may advantageously be configured such that it comprises a large number of spring elements, which are separated from one another by corresponding recesses. In order to prevent assembly errors and faulty contacts, various encoding elements for determining a defined assembly position may be provided on the pressing plate and/or the substrate. These may, for example, be guide projections, which may be inserted into corresponding grooves. The pressing plate may, for example, be made of a homogeneous, resilient insulating material having a correspondingly sufficient modulus of elasticity and good creep resistance. This variant has the advantage of optimally adjustable spring properties and, for example in conjunction with a later withdrawal and disposal, the advantage of the homogeneous material. Plastics materials such as polyamide, polyphenylene sulphide or polyphthalamide, which may also be provided with a reinforcing component, for example a glass fibre filling, are, for the most part, used. Alternatively, however, a composite consisting of a rigid insulating material and an elastomer zone may also be used for improving the long-stroke nature and long-term durability of the pressure during the production of the pressing plate. Finally, in order to limit material costs during production of the pressing plate, without thereby impairing the spring properties, an inexpensive insulating material, which does not in itself satisfy the requirements set with respect to the modulus of elasticity and creep resistance, may also be used with an integrated or connected metallic reinforcement. The metallic reinforcement is, for example, produced as a moulded punched bent part or by a holding clip made of steel wire. According to an advantageous embodiment of the present interconnect device according to the invention, the contact region comprises a dome-shaped bulge. In terms of production engineering, this may be achieved in that the three-dimensional plastics material substrate comprises a dome-shaped raised portion, via which the metal coating of the conductor track is subsequently guided. The cap- or dome-shaped bulge of the contact region has the advantage that an approximately punctiform electrical contact region is produced. If, during production of the contact region for the three-dimensional moulded interconnect device according to the invention, the conductor track is guided over a raised portion of the plastics material substrate using a hot stamping method, the configuration of the contact region as a barrel-shaped bulge is particularly advantageous for ensuring a continuous application of the conductor track to the substrate in the contact region. If, on the other hand, a pyramid-shaped bulge of the contact region is provided, infiltration of the contact region into the conductor track of the flexible flat conductor may, in this embodiment, be facilitated and, given a suitable configuration of the individual components, prior stripping of the flexible flat conductor may optionally be omitted. Moreover, the assembly of the complete 3D MED component (MED: moulded interconnect device) or the holding device for mechanically fixing the flexible flat conductor to the pressing plate may, according to the present invention, be simplified if the pressing plate is integrated with a corresponding housing of the component. This solution may be particularly advantageous for requirements placed on sealing with respect to environmental influences. The invention will be described below in greater detail with reference to configurations illustrated in the accompanying drawings. Similar or corresponding details of the plug connection according to the invention are provided with the same reference numerals in the figures. En the drawings: Fig. 1 is a perspective illustration of a three-dimensional moulded interconnect device according to an exemplary embodiment of the invention with an attached flexible flat conductor; Fig. 2 shows the interconnect device from Fig. 1 without the flexible flat conductor; Fig. 3 shows the substrate of the three-dimensional moulded interconnect device

Fig. 4 is a sectional illustration of the interconnect device from Fig. 1; Fig. 5 is a detail of the connecting region from Fig. 4; and Fig. 6 is a plan view, partially in section, of the three-dimensional moulded interconnect device of Fig. 1. Fig. 1 is a perspective illustration of a three-dimensional moulded interconnect device 100 according to an exemplary embodiment of the present invention. The interconnect device 100 comprises a substrate 102, which is provided with various conductor tracks 104 for contacting various components. The components may be any number and arrangement of active components 106, for example a Hall sensor unit for measuring rotational speed, or passive components 108. According to the invention, the interconnect device 100 comprises a contact region 110, which is even more apparent from Fig. 3. Conductors 138 (shown in Fig. 5), which are embedded in an insulating layer, of a flexible flat conductor 112 are electrically contacted in this contact region. The flexible flat conductor 112 may, for example, be an extruded flat conductor cable (flexible flat cable extruded, FFCe). However, the electrical connection according to the invention also allows other flexible flat conductors or else flexible interconnect devices of a more complex construction to be contacted.

According to the invention, the three-dimensional moulded interconnect device 100 comprises a resilient pressing plate 114 for pressing the flexible flat conductor 112 against the contact region 110. In the illustrated embodiment, the pressing plate 114 is configured as a bending beam that is secured at both ends, a first fixing region 140 (see Fig. 4) being configured as a hinge-like connection 116 and a second fixing region 142 being configured as a locking device 118. For assembly and for disassembly, the pressing plate 114 may be swivelled about an axis of rotation 120. In the illustrated embodiment, the flexible flat conductor 112 is guided around the pressing plate 114 approximately in the shape of a U and mechanically fixed to the pressing plate 114 by means of a holding clip 122. Optionally, the pressing plate (114) may be made of a fibre-reinforced, homogeneous resilient insulating material, preferably polyamide, polyphenylene sulphide or polyphthalamide. Alternatively, the pressing plate (114) may comprise a resilient metal element, such as a punched bent part. The pressing plate (114) may further comprise an electrical insulating layer, which at least partially insulates the metal element. The configuration of the pressing plate 114 is apparent from Fig. 2. The hingelike connection 116 is produced by two projections of the pressing plate 114, which sink into corresponding recesses of two fixing domes on the substrate 102. The pressing plate 114 is locked to the substrate 102 using two locking hooks 118, which engage in corresponding locking recesses 124 in the substrate 102. Alternatively, however, locking projections, which hold the pressing plate 114, may also be provided on the substrate 102. A plurality of recesses 126 divide the pressing plate 114 into a large number of spring elements 128, which allow better adaptation of the contact pressure to the base. Fig. 3 shows the substrate 102 of the three-dimensional moulded interconnect device 100 according to the invention from Fig. 1, with the pressing plate omitted. The conductor tracks 104, which are, for example, connected to the components 106, 108, are guided in the connecting region 130. The contact regions of the individual conductor tracks 110 are of a raised configuration, so the conductor track is guided via an approximately barrel-shaped or dome-shaped bulge. The electrical contact to the corresponding connection face of the flexible flat conductor therefore has a linear or punctiform (or point) configuration. Fig. 4 shows a sectional illustration through the three-dimensional moulded interconnect device 100 according to the invention. The flexible flat conductor 112 is guided around the pressing plate 114 such that a stripped connection region 132 of the embedded conductor 138 rests on the contact region of the conductor track 104. In order to ensure precise positioning of the connection region 132 and contact region 110, the pressing plate 114 also comprises a guide projection 134, which runs through associated openings in the flexible flat conductor 112. A locking hook 118, which is integrally formed on the pressing plate 114, ensures locking of the pressing plate to the substrate 102. Fig. 5 is a further enlarged view of the contact region from Fig. 4. In the connection region 132, the insulation of the flexible flat conductor 112 is open and the metallic embedded conductor 138 (which is made, for example, of copper) is exposed. However, a pyramid-shaped configuration of the contact region 110 could also allow the contact region directly to penetrate the insulation 136 of the flexible flat conductor 112. Fig. 6 is a partially open, plan view of the connecting region 130 of the three- dimensional moulded interconnect device 100 according to an exemplary embodiment of the invention. This illustration clarifies, inter alia, the function of the encoding device, which is provided on the pressing plate 114 and the fixing domes 116: the pressing plate comprises as fixing projections differently shaped projections 144, 145, each of which cooperates with correspondingly fitting recesses 146 in order to ensure during assembly that the pre-assembled pressing plate may not be fixing at the wrong orientation. Although the term "3D MTD", as used above, refers to a three-dimensional moulded interconnect device made of plastics material, it will be clear to a person skilled in the art that the principles and advantages of the solution according to the invention are transferable to all types of three-dimensional interconnect devices, such as those made of ceramic, glass or the like. The assembly of the complete 3D MED component (MTD: moulded interconnect device) or the holding device for mechanically fixing the flexible flat conductor 112 to the pressing plate 114 may, according to an exemplary embodiment of the present invention, be simplified if the pressing plate 114 or the holding device 122 is integrated with a corresponding housing of the component that surrounds the interconnect device 100. This solution may be particularly advantageous for requirements placed on sealing with respect to environmental influences.

Claims

1. Three-dimensional moulded interconnect device comprising a substrate (102), at least one electrical conductor track (104) and a connecting region (130) for releaseably contacting the at least one conductor track (104) with a flexible flat conductor (112), the at least one conductor track (104) comprising in the connection region a contact region (110), which may be electrically contacted by at least one associated connection region (132) of the flexible flat conductor (112), characterised by a pressing plate (114) for pressing the at least one connection region (132) of the flexible flat conductor (112) against the at least one contact region (110), wherein the flexible flat conductor (112) may be inserted at least partially between the pressing plate (114) and the substrate (102) and wherein the contact region (110) comprises a convex bulge for electrically contacting the connection region (132).

2. Interconnect device according to claim 1, characterised in that the pressing plate (114) comprises at least one locking device (118), which cooperates with at least one locking recess (124) on the substrate (102) for mechanically fixing the pressing plate (114).

3. Interconnect device according to claim 1, characterised in that the pressing plate (114) comprises at least one locking recess (124), which cooperates with at least one locking device (118) on the substrate (102) for mechanically fixing the pressing plate (114).

4. Interconnect device according to at least one of the preceding claims, characterised in that the pressing plate (114) is configured as a bending beam, which is fixed at both sides, comprising a first (140) and a second (142) fixing region.

5. Interconnect device according to claim 4, characterised in that the first fixing region (140) is configured as a hinge-like connection (116), so the pressing plate (114) may be swivelled about an axis of rotation (120) in order to produce the electrical contact.

6. Interconnect device according to claim 5, characterised in that the axis of rotation (120) extends substantially transversely to the longitudinal axis of the flexible flat conductor (112).

7. Interconnect device according to any one of claims 4 to 6, characterised in that the second fixing region (142) is configured as at least one locking hook (118), which, in its final mounted state, is locked to at least one associated locking recess (124) in the substrate (102).

8. Interconnect device according to at least one of the preceding claims, characterised in that the pressing plate (114) is configured such that the flexible flat conductor (112) may be deflected about the pressing plate (114) substantially in the shape ofa U.

9. Interconnect device according to at least one of the preceding claims, characterised in that the pressing plate (114) comprises at least one guide projection (134), which cooperates with at least one corresponding guide opening in the flexible flat conductor (112) on the pressing for positioning the flexible flat conductor (112).

10. Interconnect device according to at least one of the preceding claims, characterised in that a holding device (122) for mechanically fixing the flexible flat conductor (112) on the pressing plate (114) is arranged on the pressing plate (114).

11. Interconnect device according to claim 10, characterised in that the holding device is formed by a holding clip (122), which at least partially encompasses the flexible flat conductor (112) and the pressing plate (114).

12. Interconnect device according to at least one of the preceding claims, characterised in that the pressing plate (114) comprises a large number of spring elements (128), which are separated from one another by recesses (126).

13. Interconnect device according to at least one of the preceding claims, characterised in that at least one of the pressing plate (114) and the substrate (102) comprise encoding elements for determining a defined assembly position.

14. Interconnect device according to at least one of the preceding claims, characterised in that the pressing plate (114) is made of an, optionally fibre-reinforced, homogeneous resilient insulating material, preferably polyamide, polyphenylene sulphide or polyphthalamide.

15. Interconnect device according to at least one of the preceding claims, characterised in that the pressing plate (114) comprises a resilient metal element.

16. Interconnect device according to claim 15, characterised in that the pressing plate (114) comprises an electrical insulating layer, which at least partially insulates the metal element.

17. Interconnect device according to at least one of the preceding claims, characterised in that the contact region (110) comprises a dome-shaped bulge.

18. Interconnect device according to at least one of claims 1 to 16, characterised in that the contact region (110) comprises a barrel-shaped bulge.

19. Interconnect device according to at least one of claims 1 to 16, characterised in that the contact region (110) comprises a pyramid-shaped bulge.

20. Interconnect device according to any one of the preceding claims, characterised in that the pressing plate (114) is incorporated in a housing, which at least partially surrounds the interconnect device (100).

21. Interconnect device according to at least one of claims 1 to 19, characterised in that the holding device (122) is incorporated in a housing, which at least partially surrounds the interconnect device (100).

22. Method for releaseably electrically contacting a three-dimensional moulded interconnect device, which comprises a substrate, at least one electrical conductor track and a connecting region for electrically connecting the at least one conductor track to a flexible flat conductor, the connecting region comprising a convex bulge, the method comprising the following steps: positioning the flexible flat conductor between the pressing plate and the substrate such that a contact region of the at least one conductor track is aligned to be electrically contacted by at least one associated connection region of the flexible flat conductor; pressing the at last one connection region of the flexible flat conductor against the at least one contact region by means of a pressing plate.

23. Method according to claim 21, characterised in that the positioning step includes: fixing the pressing plate to the flexible flat conductor; and fixing the pressing plate to the substrate in a first fixing region.

24. Method according to either claim 21 or claim 22, characterised in that the pressing step includes: locking the pressing plate to the substrate.

25. Method according to any one of claims 21 to 23, characterised in that the pressing step includes: swivelling the pressing plate about an axis of rotation that extends through a hinge-like connection between the pressing plate and the substrate.