WO2007012514A1

WO2007012514A1 - Electrically conductive connection and method for producing the same

Info

Publication number: WO2007012514A1
Application number: PCT/EP2006/062863
Authority: WO
Inventors: Gerhard Wetzel; Helmut Deringer; Peter Sprafke
Original assignee: Robert Bosch Gmbh
Priority date: 2005-07-27
Filing date: 2006-06-02
Publication date: 2007-02-01
Also published as: DE102005035102A1

Abstract

Electrically conductive connection of at least two connection partners (1, 1*) having in each case at least one conductive layer (3, 3*), which is provided on one side with a base layer (4, 4*) and on the opposite side with a top layer (5, 5*), access openings (2, 2*), which lie one above the other in the region of the connection, being provided in the top layers (5, 5*) of the connection partners (1, 1*); and the conductive layers (3, 3*) being electrically conductively connected within these access openings (2, 2*), those regions of the base layers (4, 4*) which lie opposite the access openings (2, 2*) being retained, and a method for producing such a connection. (Figure 2)

Description

Electrically conductive connection and method for producing such

STATE OF THE ART

The present invention relates to an electrically conductive connection and a method for producing a corresponding electrical connection thereto.

In electronic modules for control devices, in particular for transmission controls, also referred to as EM - are hybrid control devices, sensors and at least one connector, a so-called gear plug, for electrically connecting the electronic module to the vehicle wiring harness or a higher-level control unit available. The electrical connection between the hybrid control unit, the sensors and the gearbox plug is made via known punched grids or flexible printed circuit boards (flex foils or FPCs). Flexible printed circuit boards have the advantage that they are completely protected by their insulation against conductive deposits in the gearbox (for example, abrasion chips) in comparison with plastic fully encapsulated stamped gratings. Although they are designed with complete insulation, they are highly flexible. This makes it possible to compensate for positional tolerances between two parts to be contacted.

Some of these electronic modules are installed in the transmission under what is known as ATF (Automatic Transmission Fluid) and are exposed to the large temperature fluctuations (-40 ° C to + 150 ° C) that occur there.

There are several embodiments of contacts between a flexible printed circuit board and functional assemblies (for example, sensors, connectors) known within an EM. For example, DE 10036900 C2 describes a contacting method in which a contact partner (for example a punched grid of a sensor) is brought to a printed circuit board which has been stripped to one side and brought into abutment. The opposite side of the film is irradiated with laser light, resulting in a

Weld connection between the copper layer of the film and the contact partner is formed.

DE 19715128 and DE 10157113 describe pressure or press-fit contacts for connecting a (flexible) conductor carrier to a contact partner or between two flexible conductor carriers. DE 10224266 shows a contacting technique between a flexible and a rigid printed circuit board, which is carried out by means of a soldering.

ADVANTAGES OF THE INVENTION

The electrically conductive connection according to the invention is distinguished by the fact that the connection partners each have only one access opening in the region of the connection which lie opposite one another, wherein the outer insulation of the connection point remains and no additional insulation measures are necessary. Another advantage is that the connecting parts have a high stability due to the remaining outer insulation.

In contrast, the method according to the invention for producing an electrically conductive connection between two connection partners takes place by means of ultrasonic welding, wherein the connection partners need only be prepared to a small extent and result in a cost-effective connection with a high degree of robustness and a flat contact point.

In addition, low-cost flexible printed circuit boards can be connected to one another as connection partners, together with a metallic conductor, for example stamped gratings, or else with flexible flat cables, whereby flat cables can also be connected to one another in this way. The flexible printed circuit boards require for connection only a one-sided access through their cover film, the base film remains isolated over the entire surface.

In an inventive electrically conductive connection of at least two connection partners, each with at least one conductor layer, which is provided on one side with a base layer and on the opposite side with a cover layer, in the cover layers of the connection partners in the region of the compound are superimposed

Access openings provided; and the conductor layers are electrically conductively connected within these access openings, wherein the areas of the base layers opposite to the access openings are maintained.

In a further embodiment, in an electrically conductive connection of at least two connection partners with at least one conductor layer which is provided on one side with a base layer and on the opposite side with a cover layer, and a conductor element in the cover layer of the one connection partner in the Connection provided an access opening; and the line layer is electrically conductively connected within these access openings to the conductor element, wherein the access opening opposite region of the base layer is maintained. Thus, the range of application of the compound according to the invention is advantageously extended to stamped grid and similar conductor elements.

In a preferred embodiment, the conductor layers are electrically conductively connected to one another or to the conductor element in a contact surface. This two-dimensional connection (for example 2 × 1 mm) advantageously improves the mechanical stability of the connection point in comparison to punctiform connections such as resistance or laser welding.

The planar connection offers a further advantage over the punctiform connections of the prior art, since their planar design has a higher current carrying capacity.

In a further preferred embodiment, the region of the base layers which is in each case opposite the access openings is essentially homogeneous and has only minor penetrations or indentations. This offers the particular advantage that the junction has a high stability.

It is preferred that the electrically conductive connection is a welded joint, in particular an ultrasonic welded joint. This reduces preparation times for the production of the connection.

It is particularly advantageous that the connection partners are designed as conductor tracks or conductor layers of flexible printed circuit boards with one-sided access, of conductor elements of stamped gratings and / or ribbon cables, since thus a large application range is made possible.

According to the invention, in the method for producing an electrically conductive connection between two connection partners, the following method steps are carried out: (S1) arranging the connection partners with exposed sections to be connected in an opposite position; (S2) compressing the sections to be joined until they lie against each other;

(S3) Welding the pressed-together sections by means of ultrasonic welding. It is advantageous that in the process step (S2) the compression takes place by means of a welding device.

In a preferred embodiment, the welding device has two mutually facing stem-shaped components with projections, which are arranged on opposite ends of the components and are preferably formed like a pin, wherein in the longitudinal direction a cross-section of a have an acute triangle. These components are compressed in step (S2) by applying a variable force. Due to the variability of this force, it is possible to connect different strong contact partners.

In method step (S3), the electrical connection is established by applying variable ultrasonic vibrations. As a result of the insulation which is also present over the whole area at the point of contact after welding, the contact / welding point has better mechanical stability than a prior art type of welding. In resistance welding, for example, the insulation of the base film in the welding area would have to be removed, resulting in a more expensive film (two-sided access) and less mechanical strength in the welding area, since in this area only the copper foil with a typical thickness of 35 μm would be used. 70 μm would be present.

After contact has been made, the connection point is largely insulated, since the insulation of the base films was only penetrated by the welding tools in small point-like areas. This results in an advantageous protection against short circuits or contact bridges by chips. A post-treatment for the preparation of an insulation of the joint is therefore not required.

For the inventive ultrasonic welding of connection partners such as flexible circuit boards with each other, flexible printed circuit board with conductor strips (punched grid) is not particularly pretreated

Surface on the metals to be welded. This is not only cost-effective, but also offers the advantage that dispensing with the tinned surface very often required in other joining techniques (in particular with stamped gratings) avoids a risk of short-circuiting by so-called tin baubles.

The effort for the representation of the contact partner at the interface very low. In the case of a stamped grid, a suitable stamping at the interface is sufficient in contrast to the laser welding method according to the prior art, in which a melting depth of the contact partner of 0.5 to 1 mm is required, which is extremely massive and expensive to avoid complete melting Design of the contact partner required.

The inventive method by means of ultrasonic welding is also distinguished from the laser welding method of the prior art by the fact that for the welding device a much lower investment is necessary.

Further advantages, details and features of the invention can be found in the subsequent description part and the drawings. DRAWINGS

The invention will be explained in more detail with reference to the exemplary embodiment given in the figures of the drawing.

It shows:

FIG. 1 two exemplary flexible circuit boards in a schematic representation in the production of a contact according to the inventive method;

FIG. FIG. 2 shows the connection according to FIG. 1 after production; FIG. and

FIG. 3 shows an exemplary connection of a flexible printed circuit board with a conductor element.

DESCRIPTION OF THE EMBODIMENT

In Fig. 1, two exemplary flexible circuit boards 1, 1 * are shown schematically in the manufacture of a contact according to the inventive method.

Such a connection point can be arranged, for example, in a transmission control of a vehicle.

The flexible printed circuit boards 1, 1 * are layered in a known manner, wherein in each case a conductor layer 3, 3 * made of copper foil of a thickness of 35 or 70 microns is usually used. The conductor layer 3, 3 * is provided on one side by a base layer 4, 4 * and on the opposite side by a cover layer 5, 5 *.

In the illustrated contacting example, the flexible printed circuit boards 1, 1 * with their cover layers 5, 5 * are arranged one above the other, wherein in the region in which a connection between the line layers 3, 3 * is to be produced, the cover layers 5, 5 * each have a so-called access opening 2, 2 *.

In this connecting portion are two stem-shaped components 6, 6 * standing opposite to the respective base layer 4, 4 * of the flexible printed circuit boards 1, 1 * applied and each acted upon by a force F. The force F causes the components 6, 6 * and thus the regions of the flexible printed circuit boards 1, 1 * to be connected to be pressed onto one another. This is possible because the base layers 4, 4 * and the conductor layers 3, 3 * have a certain flexibility and a small layer thickness.

The punch-shaped components have on their opposite front surfaces spike-like projections 7, 7 *, which have in their longitudinal direction a cross section which forms an acute-angled triangle in this example. The tips of these projections 7, 7 * respectively penetrate the base layers 4, 4 * and are in mechanical contact with the side of the conductive layer 3, 3 * which is connected to the base layer 4, 4 *. About a variability of the force F, the penetration depth and the compression force of the line layer sections to be connected can be influenced. The pressed-on line layer sections form a contact surface 8, which extends in the longitudinal direction of the superposed conductor layers 3, 3 *, ie in the drawing plane to the left and right and perpendicular thereto from the plane of the drawing up and down.

The stem-shaped components 6, 6 * are part of an ultrasonic welding device, which is not shown for reasons of clarity, and are designed as so-called sonotrodes. After pressing the line layer sections and forming the contact surface 8, these sonotrodes are subjected to ultrasonic vibrations, which execute a swinging movement S in the direction of the longitudinal plane of the contact surface 8. This oscillating movement S of the sonotrodes is transmitted mechanically via the projections 7, 7 * to the base layers 4, 4 * and to the conductor layers 3, 3 *. This results in a known manner, a welding of the contact partners in the contact surface 8 of the sections of the line layers 3, 3 *, which form a mechanical and electrical connection after welding.

A modification of the force F and the oscillatory movement S during the welding process leads to an advantageous influencing of the welding result, which can thus be adapted accordingly for differently executed contact partners.

After the welding process, the oscillatory motion S is set. The sonotrodes are withdrawn, which takes place in the opposite direction of the force F in FIG. FIG. 2 shows the welded connection point with the contact surface 8. In the connection sections above and below the contact surface 8, notches 10, the thorn-like projections 7, 7 * of the components 6, 6 * remain in the base layers 4, 4 *. Due to the strength of the base layers 4, 4 * and the geometry of the thorn-like projections 7, 7 *, the indentations 10 can be influenced. However, the notches 10 are so small in their extent or size that chips, originating from Getriebeabrieb or the like, no shorts or contact bridges between different conductor layers 1, 1 * can produce at different locations. The joint thus advantageously makes no additional insulation necessary. The mechanical strength of this joint is determined by the reinforced existing base layer sections in the region of the junction. The indentations 10, however, reduce this strength only minimally.

3 shows, by way of example, a connection point between a flexible printed circuit board 1 and a conductor element 9, which may be part of a stamped grid or a knife of a plug, for example. The flexible printed circuit board 1 corresponds with its nature to that of FIG. 1 and is arranged with its access opening 2 to the conductor element 9 facing out. Here, the sequence of welding already described above with reference to FIG. 1 applies. However, it is different in this case that only the component 6 with its thorn-like projections 7 penetrates the base layer 4 of the flexible printed circuit board 1, whereas the oppositely disposed component 6 * with its projections 7 * is in direct contact with the contact partner to be connected.

The invention is not limited to the above-described embodiments, but modifiable in a variety of ways.

For example, it is possible for the projections 7 * of the components 6 * to be designed for different contact partners having different geometric shapes.

The embodiments shown in FIGS. 1 and 3 can also be transferred to the connection of two flexible flat cables (FFC). In this case, the cover layer is formed integrally with the base layer and encloses the respective conductor element or the conductor layer. In this case, the insulation is removed on one side of the FFC in the region of the joint. Then, the two FFCs are superimposed so that copper lies on top of copper. Also in this case, the insulations are first penetrated by the projections of the sonotrodes, before the welding of the two conductive layers takes place by means of ultrasound as described above.

ROBERT BOSCH GMBH, 70442 STUTTGART

Electrically conductive connection and method for producing such

LIST OF REFERENCE NUMBERS

Claims

ROBERT BOSCH GMBH, 70442 STUTTGARTEElectrically conductive connection and method for producing such PATENT CLAIMS

1. Electrically conductive connection of at least two connection partners (1, 1 *), each having at least one conductor layer (3, 3 *), which on one side with a base layer (4, 4 *) and on the opposite side with a cover layer ( 5, 5 *) is provided, wherein in the cover layers (5, 5 *) of the connection partners (1, 1 *) in the region of the connection superimposed access openings (2, 2 *) are provided; and the conductor layers (3, 3 *) are electrically conductively connected within these access openings (2, 2 *), the regions of the base layers (4, 2 *) opposite the access openings (2, 2 *) being electrically connected.

4 *) are maintained.

2. Electrically conductive connection of at least two connection partners (1, 9) with at least one conductor layer (3) which is provided on one side with a base layer (4) and on the opposite side with a cover layer (5), and a conductor element (9), wherein in the cover layer (5) of the one connection partner (1) in the region of the connection an access opening (2) is provided; and the conductor layer (3) is electrically conductively connected to the conductor element (9) within these access openings (2), the region of the base layer (4) lying opposite the access opening (2) being retained.

3. Electrically conductive connection according to claim 1 or 2, characterized in that the conductor layers (3, 3 *) are electrically conductively connected to one another or to the conductor element (9) in a contact surface (8).

4. Electrically conductive connection according to one of claims 1 to 3, characterized the area of the base layers (4, 4 *) lying opposite the access openings (2, 2 *) is essentially homogeneous and has only slight penetrations or indentations (10).

5. Electrically conductive connection according to one of claims 1 to 4, characterized in that the electrically conductive connection is a welded connection.

6. Electrically conductive connection according to claim 5, characterized in that the electrically conductive connection is an ultrasonic welding connection.

7. Electrically conductive connection according to one of claims 1 to 6, characterized in that the connection partners (1, 1 *) as conductor tracks or conductor layers (3, 3 *) of flexible printed circuit boards with unilateral access, of conductor elements (9) of lead frames and / or ribbon cables are formed.

8. A method for producing an electrically conductive connection between two connection partners (1, 1 *, 9), comprising the following method steps:

(51) arranging the connection partners (1, 1 *, 9) with exposed sections to be joined in an opposite position;

(52) compressing the sections to be joined until they lie against each other; (S3) Welding the pressed-together sections with ultrasound.

9. The method according to claim 8, characterized in that in the method step (S2) the compression takes place by means of a welding device.

10. The method according to claim 8 or 9, characterized in that the welding device has two mutually facing stems-shaped components (6, 6 *) up, the projections (7, 7 *) have.

11. The method according to claim 10, characterized in that the projections (7, 7 *) at opposite ends of the components (6, 6 *) are arranged and formed like a pin, wherein they have a cross-section of an acute-angled triangle in the longitudinal direction.

12. The method according to any one of claims 8 to 11, characterized in that in the method step (S2) the compression takes place while applying a variable force (F).

13. The method according to any one of claims 8 to 12, characterized in that in the method step (S3), the electrical connection is made by applying variable ultrasonic vibrations.

14. The method according to any one of claims 10 to 13, characterized in that in the method step (S2), the components with their projections (7, 7 *) penetrate a base layer (4, 4 *) of a flexible printed circuit board (1, 1 *) like a spike ,