Method for monitoring a bonding process of a flex cable and flex cable

Abstract

The present invention relates to a method for monitoring the joining process of a flex cable (10) and to such a flex cable (10). The method includes a first step of pulling the flex cable (10) in a joining direction (20) of a plug (30) to which the flex cable (10) is to be connected, using a first assembly portion (12) and a second assembly portion (14) of the flex cable (10), the plug (30) being fixed to a first side (42) of a circuit board (40), and the assembly portions (12, 14) being elongated, upstanding portions on each side of the flex cable (10), extending beyond a contact area (16) in the longitudinal direction of the flex cable (10), and corresponding openings (14) in the circuit board (40). and a second step of testing the proper mating state of the flex cable (10) and the plug (30) based on electrical and / or optical and / or mechanical properties of the first and / or second assembly portions (12, 14) using portions of the first and / or second assembly portions (12, 14) accessible at the second side (44) of the circuit board (40) after mating.

Description

[Technical Field]

[0001] The present invention relates to a method for monitoring the bonding process of a flex cable, and to such a flex cable. [Background technology]

[0002] In power electronics, power semiconductors are controlled by switching signals that are transmitted via various conductor tracks or various technological solutions. For example, bonding, press-fitting of stamped parts, and the use of connection elements formed, for example, as cables and / or flex cables are conceivable for controlling power semiconductors with DBC or AMB-based techniques.

[0003] To implement a connection solution using a flex cable, a plug is first attached to the circuit board, and during the joining process between the flex cable and the plug, electrical contact areas of the flex cable can come into contact with the plug. In this connection, arrangements are known in which the plug is on the upper side of the circuit board, which is accessible and visible from the outside, and the flex cable is led from the lower side of the circuit board to the plug. For this purpose, the circuit board is provided with corresponding openings, through which the flex cable is led from the lower side of the circuit board to the upper side of the circuit board and then connected to the plug horizontally or vertically, depending on the plug arrangement.

[0004] In this way, the joining process and the result of the joining process can be visually inspected, so that in such cases a properly performed joining connection can be ensured in a simple manner. Summary of the Invention

[0005] According to a first aspect of the invention, a method is proposed for monitoring a joining process of a flex cable, and in particular for monitoring a joining process that is not or only slightly visible from the outside.

[0006] Such flex cables, also known as foil or flat cables, are made of a flexible material and typically include a large number of individual conductors or wires that are typically guided from one end of the flex cable to the other, through which electrical connections between components are established. Flex cables can be formed as single-layer or multi-layer flex cables, and electrical components and / or circuits can be pre-assembled and / or integrated into the flex cable. Particularly advantageously, flex cables include locking devices (e.g., one or more locking catches) at one or, preferably, both, ends of the flex cable to be connected to enable mating connection with the plug to be connected. Alternatively or additionally, the flex cable can be connected to the plug via a frictional connection, for example, by using a clamping device provided on the plug for connection. In this context, adhesive connections are also generally conceivable.

[0007] The method includes a first step of pulling a flex cable in a mating direction of a plug to which the flex cable is to be connected, using a first mounting portion and a second mounting portion of the flex cable, the plug being fixed to a first side of a circuit board, the mating direction of the plug extending transversely, particularly perpendicularly, to the plane of the circuit board. The first mounting portion and the second mounting portion are elongated, upstanding portions on either side of a contact area of ​​the flex cable to be connected to the plug, respectively, and extending beyond the contact area of ​​the flex cable in the longitudinal direction of the flex cable. The contact area is an area at the end of the flex cable that is accessible to wires of the flex cable for electrical contact.

[0008] The first and second mounting parts are guided from a first side through corresponding openings in the circuit board to connect the flex cable, and the mounting parts are pulled from a second side of the circuit board opposite the first side in the direction of the plug connection. The first side of the circuit board is, for example, the underside of the circuit board, and depending on the assembly and / or pre-assembly state of the circuit board, may be completely or only slightly visible and / or accessible from the outside, at least in the connection area between the plug and the flex cable. Correspondingly, the second side of the circuit board is, for example, the upper side of the circuit board, and may be completely or only slightly visible and / or accessible from the outside for inspection of the connection process and / or the connection state. In other words, both the contact area of ​​the plug and the contact area of ​​the flex cable are on the first side of the circuit board, which may be completely or only slightly accessible for inspection during and after the connection process. Naturally, the method can also be advantageously used when the first side is also accessible for external inspection of the connection process and / or the connection.

[0009] It should be noted that for the joining process according to the invention, additional assembly aids such as centering devices can be provided, allowing for easier and / or more reliable assembly of the flex cable, especially in the case of joining processes that are to be carried out "blind" or concealed.

[0010] In a second step of the method according to the present invention, portions of the first assembly portion and / or the second assembly portion that are accessible on the second side of the circuit board after bonding are used to inspect the proper bonding between the flex cable and the plug based on electrical and / or optical and / or mechanical properties of the first assembly portion and / or the second assembly portion.

[0011] The method according to the invention offers the particular advantage that the mating connection between the flex cable and the corresponding plug can be particularly reliably monitored even when the mating area between the flex cable and the plug is not or only slightly accessible or visible due to the assembly situation. This allows, inter alia, the use of mating connections in which the plug and the flex cable are both mated to the underside of the circuit board, whereby, compared to the prior art, only a small opening in the circuit board needs to be provided for the passage of the assembly section, since the flex cable does not have to be guided over its entire width from one side of the circuit board to the other side of the circuit board. This saves space, especially on the second side of the circuit board, which can be used, for example, for arranging components and / or for reducing the overall size of the circuit board.

[0012] The dependent claims show preferred developments of the invention. In an advantageous embodiment of the invention, the method further comprises a step for using the results of the bond inspection to correct and / or identify defective bonds and / or output information about the bond. The correction can advantageously be performed by an assembly tool used for the bonding process that may be performed in the first method step. The identification of defective bonds is performed, for example, by markings applied to the second side of the circuit board. The information about the bond is output, for example, as an optical and / or acoustic and / or tactile notification on a mobile terminal and / or a monitoring unit of the production line.

[0013] In a particularly advantageous embodiment of the invention, the flex cable includes at least one test contact in the contact area of ​​the flex cable, the test contact being connected to a conductor of the flex cable and guided into the first and / or second assembly sections so that the conductor is electrically contactable from the second side of the circuit board, at least in the mated state of the flex cable and the plug. To test the proper mating state of the flex cable, the conductivity is determined between the conductor in the first and / or second assembly sections and a corresponding contact of the plug, which is contactable from the second side of the circuit board. The location of the test contact within the contact area is essentially unlimited. Thus, for example, the test contact can be positioned in the center of the contact area or off-center. Furthermore, the contact of the plug used to test the conductivity can be formed as a contact surface ("pad") on the circuit board to facilitate electrical contact. The conductivity measurement is performed, for example, by an assembly tool used to mating the flex cable and the plug. Alternatively or additionally, a dedicated test tool can be used for this purpose. The conductivity is checked, for example, by applying a voltage between the electrical conductors in the assembly and the contacts of the plug corresponding to the test contacts and / or the contact surfaces electrically connected to the contacts of the plug. The conductivity can then be determined based on the current and / or resistance measured in the measuring device. In exemplary cases where the flowing current exceeds a predetermined current threshold and / or the resistance value is below a predetermined resistance value, the mating connection between the plug and the flex cable can be considered to be suitable.

[0014] It is particularly advantageous if the at least one test contact is smaller than the further contacts of the contact area and / or is offset ("lagged") from the further contacts of the contact area, so that during the joining process the further contacts are first brought into contact with the respective contacts of the plug, and only once the joining process has been completed without any defects is the at least one test contact brought into contact with the corresponding contact of the plug. This further reduces the possibility of a faulty joining connection when a current is present through the test contact, thereby making it possible to further increase the reliability of testing the adequacy of the joining connection.

[0015] Preferably, the test contact is a first test contact accessible via the first assembly part. Furthermore, the flex cable advantageously comprises a second test contact accessible via the second assembly part. Alternatively or additionally, the first test contact and / or the second test contact are each the outermost contacts of the preferably parallel-arranged contacts of the contact area. As a further alternative or addition, the proper bonding of the flex cable is checked based on individual conductivity measurements between the test contacts and the respective corresponding assembly parts and / or by a common conductivity measurement, in which the conductors of the two assembly parts or the plug contacts corresponding to the test contacts are directly electrically connected. The plug contacts corresponding to the test contacts can be permanently connected, for example, by one or more conductor tracks on a circuit board. Alternatively or additionally, the electrical connection between the plug contacts corresponding to the test contacts can be established by the assembly tool and / or a separate test tool used. A common conductivity measurement offers the advantage of ease of access by assembly tools and / or dedicated test tools, since a common circuit through both test contacts can be established by contacting only two conductors in the assembly or the corresponding two contacts in the conductivity measurement plug. Furthermore, only one measurement circuit is required. Separate conductivity measurements, on the other hand, offer the advantage of being able to test the proper contact of the first and second test contacts independently of each other, thus distinguishing between various contact failures between the flex cable and the plug.

[0016] In a further advantageous embodiment of the present invention, at least one test contact is a contact used during the production of the flex cable for signal transmission and / or electrical energy supply. This provides the advantage that additional contacts and lines do not need to be provided within the flex cable to test the adequacy of the mating connection. Such additional contacts and lines have no use during production after successful testing, but they must provide for space and material requirements. In this way, the flex cable can be constructed more cheaply and / or with less space. Alternatively or additionally, at least two test contacts with a predetermined mutual distance can be used to determine the type of fault, in particular the direction of tilt of the flex cable relative to the plug. Particularly advantageously, information about the specific fault can be used to precisely correct the faulty mating connection.

[0017] In a further advantageous embodiment of the invention, the proper connection between the flex cable and the plug is checked by applying a force to the first and / or second assembly sections in a connected state using a test tool in a direction opposite to the connection direction and measuring whether the force reaches a predetermined target value and / or whether the predetermined target value is maintained for a predetermined period of time and / or whether the position of the flex cable and / or the test tool remains substantially unchanged within the predetermined period of time. In other words, in this case, the mechanical test of the properness of the connection is performed by applying a force to one or both assembly sections and drawing conclusions about the properness of the connection and / or specific fault conditions based on the force. The determined information can be used for the appropriate correction of the connection by the assembly tool and / or the test tool. In an exemplary case where the application of a force in a direction opposite to the connection direction causes the first assembly section to collapse while the second assembly section remains unchanged, it can be assumed, for example, that the flex cable has not been successfully locked onto the plug on the side of the first assembly section. This defect may sometimes be corrected by again pulling the first assembly in the joining direction, and advantageously, after the correction is completed, the mechanical test described above is carried out again.

[0018] In a further advantageous embodiment of the invention, the inspection of the proper bonding state is performed by capturing the position and / or size and / or orientation of the first and / or second attachment parts relative to the circuit board by means of an optical sensor (e.g., an RGB and / or monochrome camera) (e.g., by means of markings on the circuit board, and / or reference objects placed on the circuit board, and / or characteristic mountings, and / or conductor track patterns on the circuit board), and determining whether the parameters captured by the optical sensor (i.e., position and / or size and / or orientation) match predetermined corresponding target parameters.

[0019] According to a second aspect of the present invention, a flexible cable is proposed, comprising: at least one contact area having a number of parallel-arranged contacts, at least one of which represents a test contact; and a first and second assembly portion, the flexible cable being designed to be connected (reversibly or irreversibly) to a corresponding plug, the contacts of the contact area establishing an electrical connection with the respective corresponding contacts of the plug. The first and second assembly portions are elongated, upstanding portions located on either side of the contact area of ​​the flexible cable, extending beyond the contact area of ​​the flexible cable in the longitudinal direction of the flexible cable. Furthermore, the first and second assembly portions are designed to be pulled toward the plug to be connected, joining the flexible cable and the plug. Furthermore, at least one test contact is designed to be connected to a conductor of the flex cable, and the conductor is guided into the first assembly part and / or the second assembly part, so that the conductor is electrically contacted via the first assembly part and / or the second assembly part.

[0020] Particularly advantageously, at least one test contact of the flex cable is made smaller than the further contacts of the contact area and / or is arranged offset ("lagged") from the further contacts of the contact area, so that the test contact is designed to come into contact with the corresponding plug only after the further contacts have already come into contact with the respective contacts of the plug during the joining process of the flex cable.

[0021] Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic diagram of a flex cable according to the invention in a first embodiment and a corresponding plug before the joining process; [Figure 2a] 1 is a schematic view of a flex cable according to the invention in a first embodiment and a corresponding plug during a first inventive mating test; [Figure 2b] 1 is a schematic diagram of a flex cable according to the present invention in a first embodiment and a corresponding plug during a mating test according to a second embodiment of the present invention; [Figure 2c] 3 is a schematic diagram of a flex cable according to the present invention in the first embodiment and a corresponding plug during a test of the mated state according to the third invention; FIG. [Figure 3] 1 is a schematic view of a flex cable according to the invention in a second embodiment and a corresponding plug during further testing of the mating state according to the invention; [Figure 4] 1 is a schematic diagram of a flex cable according to the present invention in a second embodiment during further testing of the bonded state according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0023] FIG. 1 shows a schematic diagram of a flex cable 10 according to the present invention in a first embodiment and a corresponding plug 30 before the joining process of the two components 10, 30, where the joining process is carried out to establish electrical contact between the contacts 17 of the flex cable 10 and the respective corresponding contacts of the plug 30.

[0024] The flex cable 10 is now in a state ready for carrying out the joining process between the flex cable 10 and the plug 30, and comprises a plurality of wires for establishing an electrical connection, each of which is contactable via contacts 17 of the flex cable 10. The plug 30 is attached to the first side 42 of the circuit board 40. In this state ready, the flex cable 10 is inserted into the centering unit 70, which ensures guidance of the flex cable 10 during the subsequent joining process.

[0025] The flex cable 10 has a first assembly portion 12 and a second assembly portion 14, which are used to pull the flex cable 10 in a joining direction 20 of a plug 30 to which the flex cable 10 is to be connected in a subsequent joining process, where the joining direction 20 extends perpendicular to the plane of the circuit board 40.

[0026] The first and second assembly portions 12, 14 are elongated, standing portions located on either side of the contact area 16 of the flex cable 10 to be connected with the plug 30, and extend beyond the contact area 16 of the flex cable 10 in the longitudinal direction of the flex cable 10. The assembly portions 12, 14 further each have a punched hole 90 in their end regions, into which an assembly tool (not shown) can be inserted to facilitate the implementation of the joining process. However, it should be noted that the punched hole 90 is not necessarily required for the implementation of the joining process and may therefore be omitted.

[0027] In a prepared state, the first and second mounting portions 12, 14 are guided through corresponding openings 46 (visible in FIG. 4) in the circuit board 40, and in the subsequent joining process, the mounting portions 12, 14 are pulled from a second side 44 of the circuit board 40 opposite the first side 42 in the joining direction 20 of the plug 30.

[0028] Furthermore, the flex cable 10 has a first test contact 18 in the contact area 16 of the flex cable 10, the first test contact 18 being connected to a conductor 15 of the flex cable 10, the conductor 15 being guided into the first assembly part 12, so that the first test contact 18 can be electrically contacted via the first assembly part 12.

[0029] The flex cable 10 further comprises a second test contact 19 in the contact area 16 of the flex cable 10, the second test contact 19 being connected to a conductor 15 of the flex cable 10, the conductor 15 being guided into the second assembly portion 14 so that the second test contact 19 can be electrically contacted via the second assembly portion 14.

[0030] Here, the first test contact 18 and the second test contact 19 are each the outermost contacts 17 of the contact area 16 of the flex cable 10, but are not limited to such an arrangement. Furthermore, both test contacts 18, 19 are arranged offset ("lagged") with respect to the further contacts 17 arranged in parallel in the contact area 16, so that during the mating process, the further contacts 17 first contact the contacts of the plug 30 before the test contacts 18, 19 contact their corresponding contacts of the plug 30. Here, the test contacts 18, 19 are formed such that when they establish an electrical connection with the corresponding contacts of the plug 30, the flex cable 10 and the plug 30 can be considered to be in a properly mated state.

[0031] The contacts of the plug 30 corresponding to the test contacts 18, 19 are electrically connected to respective contact surfaces 80 ("pads") provided on the second side 44 of the circuit board 40 for electrical contact by the test tool 50 shown in FIG. 2.

[0032] FIG. 2 a shows a schematic view of a flex cable 10 according to the invention in a first embodiment and a corresponding plug 30 during testing of a first inventive connection between the flex cable 10 and the plug 30 .

[0033] 2a shows the flex cable 10 and plug 30 according to FIG. 1, now joined together, so that to avoid redundancies, only the differences between FIG. 1 and FIG. 2a will be substantially described below.

[0034] 2a, the bonding process has been completed by pulling the flex cable 10 in the bonding direction 20, and testing for proper bonding can begin. Here, this is done based on measuring current with the respective current sensors 52 to ensure conductivity between the test contacts 18, 19 and their respective contacts on the plug 30.

[0035] Now, when the test tool 50 is electrically connected to the contact surfaces 80 and the corresponding conductors 15 in the assemblies 12, 14, respectively, and the test contacts 18, 19 are properly contacted to the plug 30, a current can be measured.

[0036] Inspecting the first test contact 18 and the second test contact 19 separately allows for accurate identification of any fault conditions that may exist, since it is then possible to determine which of the test contacts 18, 19 may be in poor contact, and therefore, based on this information, precise correction of the fault can be advantageously carried out.

[0037] It should be noted that the two contact surfaces 80 on the second side of the circuit board 40 can be permanently or temporarily electrically connected, so that a total current measurement can alternatively be made between the conductors 15 at the first assembly 12 and the conductors 15 at the second assembly 14.

[0038] FIG. 2b shows a schematic view of a flex cable according to the invention in a first embodiment and a corresponding plug during a second inventive mating test. To avoid repetition, only the differences between FIG. 2b and FIG. 2a will be described below, and for the rest please refer to the description of FIG. 2a.

[0039] In FIG. 2b, the properness of the bond is checked based on a single voltage source and a single current sensor 52 by connecting the contacts of each test tool 50 as shown in FIG. 2b, so that if a proper bond exists, a circuit is closed by the test tool 52.

[0040] FIG. 2c shows a schematic view of a flex cable according to the invention in the first embodiment and a corresponding plug during a third inventive mating test. To avoid repetition, only the differences between Figure 2c and Figure 2b will be described below, and for the rest please refer to the description of Figures 2a and 2b.

[0041] In Figure 2c, the correctness of the connection is tested by completing a circuit with a conductor track 41 arranged on the circuit board 40, which is electrically connected to the contacts of the plug 30 corresponding to the test contacts 18, 19.

[0042] Thus, the test tool 50 contacting the contact surface 80 in Figures 2a and 2b (not required in Figure 2c) can be omitted, as the circuit is closed by the conductor track 41 when a suitable bond is present.

[0043] FIG. 3 shows a schematic view of a flex cable 10 according to the invention in a second embodiment and a corresponding plug 30 during further testing of the mating state according to the invention. There are many similarities between Figures 1, 2 and 3, so to avoid repetition, the following mainly focuses on the differences between Figure 3 and Figures 1 and 2.

[0044] In Figure 3, the flex cable does not include conductors 15 at assembly portions 12, 14, nor does it include test contacts 18, 19, because in this case a purely mechanical test of proper bonding between flex cable 10 and plug 30 is performed. This does not exclude such a mechanical test from being performed with a flex cable 10 formed in accordance with Figures 1 and 2.

[0045] Here, the first assembly part 12 and the second assembly part 14 are subjected in a joined state to a predetermined test force 55 acting in a direction opposite to the joining direction 20 by a test tool 50, which here also serves as an assembly tool 95 for the joining process. The test force 55 is advantageously set to be less than a force designed to release the locking connection between the joined flex cable 10 and the plug 30, but large enough to detect a faulty joint.

[0046] Based on the test force 55, it is determined whether the test force 55 reaches a predetermined target value, whether the predetermined target value is maintained for a predetermined period of time, and whether the positions of the flex cable and the test tool do not change substantially within the predetermined period of time. If the above assumptions are met, the bond condition can be considered to be proper.

[0047] 3 further shows a centering pin 75 which serves to position the centering unit 70 relative to the circuit board 40. Such a centering pin 75 can also be advantageously applied in the configurations shown in FIGS. 1, 2a, 2b, and 2c.

[0048] FIG. 4 shows a schematic view of a flex cable 10 according to the invention in a second embodiment during further testing of the bonded state according to the invention. Here, testing for proper bonding between each flex cable 10 and each plug (not visible here) is performed by an optical sensor formed as a camera 60, which is designed to capture, on the second side 44 of the circuit board 40, the position, size and orientation of each of the first and second assembly parts 12, 14 relative to the circuit board 40. Here, the use of the circuit board 40 as a reference is ensured by evaluation of a characteristic conductor track pattern (not shown). Based on the conductor track pattern, the target distance and target angle of the camera 60 relative to the circuit board 40 can thus be adjusted and / or deviations therein can be corrected by calculation, thereby enabling a reliable inspection of the target parameters of the assembly parts 12, 14.

[0049] In this manner, a proper bond can be determined when the parameters captured by the camera 60 match the predetermined corresponding target parameters for a proper bond.

[0050] Furthermore, FIG. 4 shows openings 46 provided in the circuit board 40, through which the mounting portions 12, 14 of each flex cable 10 can be guided from the first side 42 of the circuit board 40 to the second side 44 of the circuit board 40.

Claims

1. A method for monitoring a bonding process of a flex cable (10), comprising: a first step (100) of pulling the flex cable (10) in a mating direction (20) of a plug (30) to which the flex cable (10) is to be connected, using a first assembly portion (12) and a second assembly portion (14) of the flex cable (10); The plug (30) is fixed to a first side (42) of a circuit board (40), and the mating direction (20) of the plug (30) extends transversely, in particular perpendicularly, to the plane of the circuit board (40); the first and second mounting portions (12, 14) are elongated, standing portions located on either side of a contact area (16) of the flex cable (10) to be connected to the plug (30), and extend beyond the contact area (16) of the flex cable (10) in the longitudinal direction of the flex cable (10); the first and second mounting portions (12, 14) are guided through corresponding openings (46) of the circuit board (40) to join the flex cable (10), and the mounting portions (12, 14) are pulled from a second side (44) of the circuit board (40) opposite the first side (42) in the joining direction (20) of the plug (30); a second step (200) for inspecting a proper connection between the flex cable (10) and the plug (30) based on electrical and / or optical and / or mechanical properties of the first assembly portion (12) and / or the second assembly portion (14) using portions of the first assembly portion (12) and / or the second assembly portion (14) accessible on the second side (44) of the circuit board (40) after the connection; Contains method.

2. The method of claim 1 , further comprising using results of the inspection of the bond condition to correct and / or identify poor bond conditions and / or output information about the bond condition.

3. the flex cable (10) comprises at least one test contact (18) in the contact area (16) of the flex cable (10), the test contact (18) being connected to a conductor (15) of the flex cable (10), the conductor (15) being guided into the first assembly part (12) and / or the second assembly part (14), so that the conductor (15) can be electrically contacted from the second side (44) of the circuit board (40), at least in a mated state between the flex cable (10) and the plug (30); To test the proper connection of the flex cable (10), the conductivity is determined between the conductors (15) in the first assembly portion (12) and / or the second assembly portion (14) and contacts of the plug (30) that correspond to the test contacts (18) accessible from the second side (44) of the circuit board (40).

3. The method according to claim 1 or 2.

4. 4. The method according to claim 3, wherein the at least one test contact (18) is formed smaller than the further contacts (17) of the contact area (16) and / or is offset from the further contacts (17) of the contact area (16), so that during the bonding process, the further contacts (16) are first brought into contact with the respective contacts of the plug (30), and only when the bonding process is completed without any defects is the test contact (18) brought into contact with the corresponding contact of the plug (30).

5. the test contact is a first test contact (18) accessible via the first assembly part (12), and the flex cable (10) has a second test contact (19) accessible via the second assembly part (14); and / or the first test contact (18) and / or the second test contact (19) are, respectively, the outermost contacts of the parallel-arranged contacts (17, 18, 19) of the contact area (16); and / or the proper connection of the flex cable (10) is checked based on individual conductivity measurements between the test contacts (18, 19) and the corresponding assembly parts (12, 14) and / or by a common conductivity measurement, in which the conductors (15) of the two assembly parts (12, 14) or the contacts of the plug (30) corresponding to the test contacts (18, 19) are directly electrically connected; 5. The method according to claim 3 or 4.

6. the at least one test contact (18) is a contact used in the production use of the flex cable (10) for signal transmission and / or electrical energy supply; and / or Using at least two test contacts (18, 19) having a predetermined mutual distance, the type of fault condition, in particular the direction of tilt of the flex cable (10) relative to the plug (30), is determined.

6. The method according to any one of claims 3 to 5.

7. said inspecting for proper bonding condition comprises: a test tool (50) applies a force to the first assembly part (12) and / or the second assembly part (14) in the joined state in a direction opposite to the joining direction (20); It is determined whether the force reaches a predetermined target value and / or whether the predetermined target value is maintained for a predetermined period of time and / or whether the position of the flex cable (10) and / or the test tool (50) remains substantially unchanged within the predetermined period of time. The method according to any one of claims 1 to 6, wherein the method is carried out by

8. The inspection of the proper bond condition comprises: an optical sensor (60) captures the position, size, and / or orientation of the first mounting portion (12) and / or the second mounting portion (14) relative to the circuit board (40); It is determined whether the parameters captured by the optical sensor (60) match predetermined corresponding target parameters. The method according to any one of claims 1 to 7, wherein the method is carried out by

9. a contact area (16) having a number of parallel-arranged contacts (17), at least one of said contacts (17) representing a test contact (18); A first assembly portion (12) and a second assembly portion (14) A flex cable (10) comprising: the flexible cable (10) is designed to be connected to a corresponding plug (30), and the contacts (17, 18) of the contact area (16) establish an electrical connection with the respective corresponding contacts of the plug (30); The first assembly portion (12) and the second assembly portion (14) an elongated raised portion on each side of the contact area (16) of the flex cable (10), the raised portion extending beyond the contact area (16) of the flex cable (10) in the longitudinal direction of the flex cable (10); designed to be pulled in the direction of the plug (30) to be connected in order to join the flex cable (10) and the plug (30); the at least one test contact (18) is designed to be connected to a conductor (15) of the flexible cable (10), the conductor (15) being guided into the first assembly part (12) and / or the second assembly part (14), so that the conductor (15) is electrically contacted via the first assembly part (12) and / or the second assembly part (14); Flex cable (10).

10. 10. The flex cable (10) according to claim 9, wherein the at least one test contact (18) is formed smaller than the further contacts (17) of the contact area (16) and / or is arranged offset from the further contacts (17) of the contact area (16), so that the test contact (18) is designed to come into contact with the corresponding plug (30) only after the further contacts (17) have already come into contact with the respective contacts of the plug (30) during the joining process of the flex cable (10).

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