Method for manufacturing a board harness assembly

Abstract

The application relates to a preparation method of a card wire harness assembly and belongs to the technical field of signal cable connectors. The application directly adopts wire harness welding with a card, instead of using the wire core exposed after the signal cable is returned to the outer sheath and the shielding layer to weld the card, and then assembling the outer sheath with the shielding layer built-in into the wire harness welded with the card into a complete signal cable by means of a guide body, so that the operation of returning is avoided, and the swing life of the product is improved.

Description

Technical Field

[0001] This invention relates to a method for manufacturing circuit board harness assemblies, belonging to the field of signal cable connector technology. Background Technology

[0002] In medical devices, especially endoscopic equipment, the lens is connected to a circuit board via a wiring harness. The circuit board then plugs into a slot on the motherboard of a computer. A circuit board is typically a printed circuit board that integrates various electronic components and interfaces to connect different internal computer parts and external devices, enabling data transmission, processing, and conversion.

[0003] When an endoscope is in use, various electronic devices, such as medical instruments and lighting equipment, are present, which can generate electromagnetic interference. Therefore, the wiring harness connecting the lens to the circuit board needs to use a signal cable. The metal shielding layer of the signal cable can effectively block external electromagnetic interference from entering the wiring harness, ensuring that the images, data, and other signals transmitted by the endoscope are not interfered with, and ensuring clear images and accurate data. For example, invention patent application CN 118117395A discloses a connector structure, a communication cable, an endoscope camera, and an assembly method. It designs a connector structure including a connecting part, a mating part, and a wiring part. The connecting part has conductive contacts, the mating part has an installation cavity and a potting hole, and the wiring part is embedded in the mating part. The connecting part is fixed by welding and applying glue to ensure the reliability of the connection. The connecting part is a flat circuit board, and the installation cavity is a through groove formed on the inner wall of the mating part that matches the shape of the circuit board. The communication cable is a camera signal cable. The structure of the camera signal cable, from the inside out, includes a conductor, an insulation layer, a shielding layer, and an outer sheath. Typically, the conductor consists of multiple copper wires, each covered with the aforementioned insulation layer. The shielding layer is a braided metal mesh. The outer sheath is usually a TPU layer, providing good flexibility. This type of camera signal cable is the signal cable described above.

[0004] In existing technology, when connecting signal cables to circuit boards, the outer sheath must first be stripped. Then, the outer sheath and braided wire mesh of the signal cable are retracted. This involves pulling on the ends of the wire cores and utilizing the flexibility and extensibility of the outer sheath and braided wire mesh to retract them, exposing a longer wire end. In this retracted state, the outer sheath and braided wire mesh are curled around the wire core without damaging the structure, allowing for later restoration. After sufficient wire ends are exposed, they are laid out, then soldered to the circuit board. The outer sheath and braided wire mesh are then restored, and finally, termination assembly is performed. Termination assembly is equivalent to forming the connector structure in CN 118117395A. Throughout this process, while retracting the outer sheath and braided wire mesh does not damage their structure, it inevitably causes deformation of the braided wire mesh, thus affecting the overall lifespan of the product, such as a swing life of approximately 200,000 cycles. Summary of the Invention

[0005] This invention aims to solve the above-mentioned problems by providing a method for manufacturing circuit board wiring harness assemblies. By changing the process sequence and further improving the process, this invention solves the technical problem of low swing life in circuit board wiring harness assemblies.

[0006] The technical solution of the present invention to solve the above problems is as follows: The method for manufacturing circuit board wiring harness assemblies includes the following steps: S1. Provide a wire harness with multiple wire cores and solder the wire harness to the board; S2. A guide body and an outer sheath with a built-in shielding layer are provided. The guide body is used to pass through the outer sheath to bring out the wire harness, so that the outer sheath is fitted onto the wire harness. S3. Terminal assembly to obtain the board wiring harness assembly.

[0007] In this field, existing technologies for soldering wire harnesses to circuit boards typically involve first stripping the outer sheath and shielding layer of the signal cable to expose the wire core. Then, mechanical force is used to retract the outer sheath and shielding layer, ensuring the exposed wire core has sufficient length for wiring. The wire core is then laser-cut to remove the insulation layer, exposing the copper / silver conductor. This copper / silver conductor is then soldered to the circuit board. Finally, the outer sheath and shielding layer are retracted, restoring the cable. Directly stripping the outer sheath and braided wire without retraction results in excessively long wire cores at the connectors. Conversely, without stripping the outer sheath and braided wire and without retraction, the wire cores cannot be wired, let alone soldered to the circuit board. Therefore, in existing technologies, retraction followed by restoration is a compromise.

[0008] The technical solution of this invention breaks with the biases of existing technologies and abandons the technical route of soldering complete signal cables to circuit boards. Instead, the wire harness is directly soldered to the circuit board, and then, starting from the end of the wire harness furthest from the soldered circuit board, a guide is used to guide the wire harness through the outer sheath containing the built-in shielding layer, assembling it into a complete signal cable. In other words, this invention abandons the existing approach of directly using signal cables, adopting a technology of soldering first and then assembling. This solves the problem of deformation and damage to the shielding layer when retracting the outer sheath and shielding layer, thereby increasing the product's swing life from approximately 200,000 cycles to approximately 300,000 cycles.

[0009] In the above technical solution of the present invention, since the signal cable is assembled later, its outer sheath with built-in shielding layer can be slightly larger than that of the original signal cable. This makes it easier to assemble the wire harness with the soldered circuit board and the outer sheath with built-in shielding layer into a signal cable through the guide. Preferably, the inner diameter d of the shielding layer of the assembled signal cable is 0.1~0.5mm larger than the inner diameter d of the shielding layer of the original signal cable. The guide acts as a medium for threading, and its technical principle is similar to that in the garment manufacturing industry, when faced with the need to sew and cut at least two pieces of fabric, a needle is used to pass the sewing thread through them.

[0010] As a preferred embodiment of the above technical solution, the length of the guide body exceeds that of the outer sheath. When the guide body is used to pass through the outer sheath to bring out the wire harness, the end of the guide body close to the wire harness is pre-tied with the end of the wire harness away from the soldering board.

[0011] As a preferred embodiment of the above technical solution, the guide body is a metal wire.

[0012] As a further preferred embodiment of the above technical solution, the guide body is a steel wire.

[0013] As a preferred embodiment of the above technical solution, the binding is achieved by wrapping and securing with single-sided adhesive tape.

[0014] As a preferred embodiment of the above technical solution, the end of the guide body away from the wire harness is fixed to the workbench.

[0015] As a preferred embodiment of the above technical solution, in step S2, the guide body is used to bring the wire harness out through the outer sheath. Specifically, the outer sheath is first put on the guide body, and then the outer sheath is moved towards the end of the wire harness that is close to the soldering plate until the end of the wire harness that is away from the soldering plate passes through the outer sheath.

[0016] As a preferred embodiment of the above technical solution, the step S1 of soldering the wire harness to the board specifically includes the following steps: S11. Arrange the wire harness using a tooling fixture, so that the ends of multiple wire cores are arranged in a row and fixed on the tooling fixture, and then cut the ends of these wire cores flat. S12. Use a laser to cut at the same position at the end of each wire core; S13. Strip the insulation layer from the end of the wire core; the insulation layer is broken at the laser cutting point. S14. Solder the wire harness to the board.

[0017] As a preferred embodiment of the above technical solution, in step S2, after the outer sheath is fitted onto the wire harness, the outer sheath is continuously swung to release the mechanical stress generated by the fitting of the outer sheath onto the wire harness.

[0018] As a preferred embodiment of the above technical solution, while continuously swinging the outer sheath or back and forth, the multiple cores of the wire harness are pulled out one by one at the end of the wire harness away from the welding board.

[0019] As a preferred embodiment of the above technical solution, in step S2, after the outer sheath is fitted onto the wire harness, the end of the shielding layer is also soldered to the circuit board.

[0020] As a preferred embodiment of the above technical solution, in step S3, the terminal assembly includes encapsulating the connection between the wire harness and the board with an insulating plastic shell.

[0021] In summary, the present invention has the following beneficial effects: 1. This invention breaks with the prejudice of the prior art by directly soldering the wire harness to the board, instead of using the exposed wire core after the outer sheath and shielding layer of the signal cable are removed to solder the board. Then, with the help of the guide, the outer sheath with the built-in shielding layer and the wire harness with the board soldered are assembled into a complete signal cable, avoiding the removal operation and thus improving the swing life of the product. 2. Since the present invention does not require the use of original signal cables, it can save processes, that is, there is no need to braid a shielding layer on the wire harness; and the assembled signal cable has a slightly larger outer diameter than the original signal cable, with the same internal wire harness. This not only makes the assembly of the signal cable more convenient, but also makes the assembled signal cable more suitable for bending use, further improving the swing life of the product. Detailed Implementation

[0022] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. Any changes made by those skilled in the art after reading the specification of the present invention, as long as they are within the scope of the claims, will be protected by patent law. Example

[0023] Medical endoscope board wiring harness assembly Wire core configuration: 13 wire cores (11 signal wires, 2 spare wires), wire diameter 0.1mm, insulation layer is PE.

[0024] Steps S1~S4: Tooling the cabling, laser cutting to remove the insulation layer, and soldering it to the corresponding contacts on the circuit board.

[0025] Step S5: Select a shielding layer with an inner diameter of 6mm (original cable 5.8mm), and add an outer sheath by steel wire traction.

[0026] Steps S6~S7: The shielding layer is soldered to the grounding terminal of the board, and the shell is encapsulated with epoxy resin.

[0027] Specifically, a circuit board wiring harness assembly is used for communication connection between an endoscope lens and a device host, including a circuit board and a signal cable communicating with the circuit board. The signal cable includes a wiring harness, a shielding layer covering the wiring harness, and an outer sheath covering the shielding layer. Furthermore, the wiring harness includes 13 wire cores, two of which are spare cores. Each wire core includes a copper conductor and an insulating layer covering the copper conductor. Eleven of the copper conductors are soldered to a first position (corresponding to a contact point) on the circuit board; the shielding layer is soldered to a second position (the circuit board grounding terminal). Additionally, the connection between the wiring harness and the circuit board is encapsulated with insulating plastic (epoxy resin).

[0028] In this embodiment, the specific preparation method of the above-mentioned board wiring harness assembly includes the following steps: S1. Provide a wire harness with 13 wire cores, use a tool to arrange 11 of the wire cores so that the ends of the 11 wire cores are arranged in a row and fixed on the tool, and cut the ends of the wire cores flat. S2. Use a laser to cut at the same position at the end of these 11 wire cores; S3. Strip the insulation layer from the end of the wire core to expose the internal copper conductor; S4. Solder the wire harness to the board through the exposed copper wire; S5. Provide a steel wire rope as a guide and an outer sheath with a built-in shielding layer; the length of the steel wire rope exceeds the outer sheath, the steel wire rope is threaded into the outer sheath, and both ends of the steel wire rope extend out of the outer sheath; the end of the wire harness away from the welding plate is wrapped and fixed to one end of the steel wire rope with single-sided tape; the other end of the steel wire rope is fixed to the workbench, and then the outer sheath is held and gently pulled while shaking or swinging to disperse the mechanical stress between the wire harness and the outer sheath; the end of the wire harness away from the welding plate is pulled out of the outer sheath, so that the outer sheath is fitted onto the wire harness; after the outer sheath is fitted onto the wire harness, the outer sheath is continuously swung to release the mechanical stress generated by the fitting of the outer sheath onto the wire harness; S6. Weld the end of the shielding layer inside the outer sheath to the board; S7. Insulating plastic is used to encapsulate the connection between the wire harness and the board, thus obtaining the board harness assembly for medical endoscopes.

[0029] Results: Suitable for high-frequency bending environments; Test results: Swing life reaches 300,000 cycles. Example

[0030] Wiring harness assembly for industrial sensors Wire core configuration: 18 wire cores (16 signal wires, 2 spare wires), wire diameter 0.08mm, conductor is silver wire, insulation layer is PVC.

[0031] Steps S1~S4: Tooling the cabling, laser cutting to remove the insulation layer, and soldering it to the corresponding contacts on the circuit board.

[0032] Step S5: Select a shielding layer with an inner diameter of 6.5mm (original wire 6.2mm), and add an outer sheath for steel wire rope traction.

[0033] Steps S6~S7: The shielding layer is soldered to the grounding terminal of the board, and the shell is encapsulated with epoxy resin.

[0034] Specifically, a board-based wiring harness assembly is used for communication connection between industrial sensors and a host device, including a board and a signal cable communicating with the board. The signal cable includes a wiring harness, a shielding layer covering the wiring harness, and an outer sheath covering the shielding layer. Furthermore, the wiring harness includes 18 wire cores, two of which are spare cores. Each wire core includes a silver conductor and an insulating layer covering the silver conductor. The silver conductors of 16 wire cores are soldered to a first position (corresponding to a contact) on the board; the shielding layer is soldered to a second position (the board's ground terminal). Additionally, the connection between the wiring harness and the board is encapsulated with insulating plastic (epoxy resin).

[0035] In this embodiment, the specific preparation method of the above-mentioned board wiring harness assembly includes the following steps: S1. Provide a wire harness with 18 wire cores, use a tool to arrange 16 of the wire cores so that the ends of the 16 wire cores are arranged in a row and fixed on the tool, and cut the ends of the wire cores flat. S2. Use a laser to cut at the same position at the end of these 16 wire cores; S3. Strip the insulation layer from the end of the wire core to expose the internal silver wire conductor; S4. Solder the wire harness to the corresponding contact of the circuit board through the exposed silver wire; S5. Provide a steel wire rope as a guide and an outer sheath with a built-in shielding layer; the length of the steel wire rope exceeds the outer sheath, the steel wire rope is threaded into the outer sheath, and both ends of the steel wire rope extend out of the outer sheath; the end of the wire harness away from the welding plate is wrapped and fixed to one end of the steel wire rope with single-sided tape; the other end of the steel wire rope is fixed to the workbench, then the outer sheath is held and gently pulled, and the outer sheath is gently swung after each small distance to disperse the mechanical stress between the wire harness and the outer sheath, the end of the wire harness away from the welding plate is pulled out of the outer sheath, so that the outer sheath is fitted onto the wire harness; after the outer sheath is fitted onto the wire harness, the outer sheath is continued to be swung to release the mechanical stress generated by the fitting of the outer sheath onto the wire harness; S6. Solder the end of the shielding layer inside the outer sheath to the grounding terminal of the board; S7. Insulating plastic is used to encapsulate the connection between the wire harness and the board, and the final product is the board wire harness assembly for industrial sensors.

[0036] Results: Suitable for high-frequency bending environments; Test results: 300,000 swing cycles.

[0037] Comparative Example 1 Medical endoscope board wiring harness assembly Wire core configuration: 13 wire cores (11 signal wires, 2 spare wires), wire diameter 0.1mm, insulation layer is PE.

[0038] Steps S1~S4: Tooling the cabling, laser cutting to remove the insulation layer, and soldering it to the corresponding contacts on the circuit board.

[0039] Step S5: Select a shielding layer with an inner diameter of 6mm (original cable 5.8mm), and add an outer sheath by steel wire traction.

[0040] Steps S6~S7: The shielding layer is soldered to the grounding terminal of the board, and the shell is encapsulated with epoxy resin.

[0041] Specifically, a circuit board wiring harness assembly is used for communication connection between an endoscope lens and a device host, including a circuit board and a signal cable communicating with the circuit board. The signal cable includes a wiring harness, a shielding layer covering the wiring harness, and an outer sheath covering the shielding layer. Furthermore, the wiring harness includes 13 wire cores, two of which are spare cores. Each wire core includes a copper conductor and an insulating layer covering the copper conductor. Eleven of the copper conductors are soldered to a first position (corresponding to a contact point) on the circuit board; the shielding layer is soldered to a second position (the circuit board grounding terminal). Additionally, the connection between the wiring harness and the circuit board is encapsulated with insulating plastic (epoxy resin).

[0042] In this embodiment, the specific preparation method of the above-mentioned board wiring harness assembly includes the following steps: S1. Provide a communication cable with 13 cores; S2. Retract the outer sheath and metal wire braided shielding layer of the communication cable; specifically, pull the end of the wire core and use the flexibility and extensibility of the outer sheath and metal wire braid to retract them so that a longer wire end of the wire core is exposed. S3. Use a tool to arrange 11 wire cores so that the ends of these 11 wire cores are arranged in a row and fixed on the tool, and then cut the ends of these wire cores flat. S4. Use a laser to cut at the same position at the end of these 11 wire cores; S5. Strip the insulation layer from the end of the wire core to expose the internal copper conductor; S6. Solder the wire harness to the board through the exposed copper wire; S7. Restore the metal wire mesh and weld its ends to the grounding terminal of the board; S8. Restore the outer sheath as described above; S9. Insulating plastic is used to encapsulate the connection between the wire harness and the board, thus obtaining the board harness assembly for medical endoscopes.

[0043] Results: Suitable for high-frequency bending environments; Test results: 200,000 swing cycles.

[0044] Cable swing life testing is used to evaluate the durability of cables under repeated bending, torsion, and other mechanical stresses, and is particularly suitable for high-frequency bending scenarios such as medical equipment and industrial sensors. The following is a test method based on industry practice.

[0045] Test equipment and conditions Test equipment: The cable swing tester mainly consists of the following components: Fixture: Holds one end of the cable, simulating the fixed end of the equipment; Movable clamp: Holds the other end of the cable and swings along a set trajectory to simulate an actual bending action; Counter: Records the number of swings, with an accuracy of ±1.

[0046] Test conditions: Bending angle: set according to the application scenario (such as 90°~180° commonly used for medical endoscopes).

[0047] Oscillation frequency: 1~5 Hz (2 Hz for medical equipment to simulate the actual operating rhythm).

[0048] Load: Suspend a standard weight (e.g., 100g) at the end of the cable to simulate actual force.

[0049] Ambient temperature and humidity: normal temperature (25±5℃), humidity ≤60% RH.

[0050] Test steps Sample preparation: Cut a sample of the cable to be tested, the length of which is determined according to the spacing of the clamps (300~500mm).

[0051] Remove the outer sheath and shielding layer from both ends to expose the conductors and solder them to the test terminals to ensure reliable electrical connection.

[0052] Fixture installation: Secure one end of the cable to the fixed clamp and the other end to the movable clamp, ensuring that the cable is in a naturally straight state.

[0053] Adjust the clamp spacing so that the bending radius of the cable when it swings meets the design requirements (e.g., the bending radius of medical cables is ≥ 5 times the wire diameter).

[0054] Parameter settings: Set the swing angle (180°), frequency (2 Hz), and number of cycles (target 300,000 cycles).

[0055] To simulate an actual load, suspend a weight (100g) at the end of the movable clamp.

[0056] Start the test: Start the swing tester, pause the test every 10,000 cycles, visually inspect the cable outer sheath for cracks and the shielding layer for breaks, and record the continuity data.

[0057] Termination conditions: Electrical failure: sudden change in resistance value or interruption of signal transmission.

[0058] Mechanical failure: damage to the outer sheath, breakage of the conductor, or complete detachment of the shielding layer.

[0059] If the target number of cycles (300,000) is reached and there is no failure, it is considered qualified.

[0060] Results Evaluation Lifespan calculation: Record the number of loops when a sample fails, and record the minimum value (3 sets of samples).

[0061] Precautions Clamp design: To prevent sharp edges from damaging cables, the clamps are lined with silicone or nylon pads.

[0062] Cable securing: Ensure both ends are securely clamped to prevent slippage during testing.

[0063] Environmental control: Avoid high temperature and high humidity environments that accelerate material aging (unless simulating special working conditions).

[0064] Sample size: Three groups of samples were tested to ensure data reliability.

Claims

1. A method for preparing a circuit board wiring harness assembly, comprising the following steps: S1. Provide a wire harness with multiple wire cores and solder the wire harness to the board; S2. A guide body and an outer sheath with a built-in shielding layer are provided. The guide body is used to pass through the outer sheath to bring out the wire harness, so that the outer sheath is fitted onto the wire harness. S3. Terminal assembly to obtain the board wiring harness assembly; The length of the guide body exceeds that of the outer sheath. When the guide body is used to pass through the outer sheath to bring out the wire harness, the end of the guide body near the wire harness is pre-tied with the end of the wire harness away from the soldering board. The binding is achieved by wrapping and securing with single-sided tape. The end of the guide body away from the wire harness is fixed to the workbench; In step S2, the guide body is used to bring the wire harness out through the outer sheath. Specifically, the outer sheath is first put on the guide body, and then the outer sheath is moved towards the end of the wire harness that is closer to the soldering board until the end of the wire harness that is away from the soldering board passes through the outer sheath.

2. The method for preparing the board wiring harness assembly according to claim 1, characterized in that, Step S1, which involves soldering the wire harness to the circuit board, specifically includes the following steps: S11. Arrange the wire harness using a tooling fixture, so that the ends of multiple wire cores are arranged in a row and fixed on the tooling fixture, and then cut the ends of these wire cores flat. S12. Use a laser to cut at the same position at the end of each wire core; S13. Strip the insulation layer from the ends of the wire core; S14. Solder the wire harness to the board.

3. The method for preparing the board wiring harness assembly according to claim 1, characterized in that, In step S2, after the outer sheath is fitted onto the wire harness, the outer sheath is continuously swung to release the mechanical stress generated by the fitting of the outer sheath onto the wire harness.

4. The method for preparing the board wiring harness assembly according to claim 3, characterized in that, While continuously swinging the outer sheath, or back and forth, the multiple cores of the wire harness are pulled out one by one at the end of the wire harness away from the soldering board.

5. The method for preparing the board wiring harness assembly according to claim 1, characterized in that, In step S2, after the outer sheath is fitted onto the wire harness, the end of the shielding layer is soldered to the circuit board.

6. The method for preparing the board wiring harness assembly according to claim 5, characterized in that, In step S3, the terminal assembly includes encapsulating the connection between the wire harness and the board with an insulating plastic shell.