A method of functional testing and a test fixture for a circuit board

Abstract

This invention relates to the field of circuit board testing technology, specifically to a functional testing method and fixture for circuit boards. The method includes: placing the circuit board under test on a support platform; acquiring an image of the target interface area and determining its coordinates using a vision positioning system; and driving a programmable three-dimensional motion platform to align an interface connection device with the target interface area. The interface connection device is equipped with elastic connection pins with conductive contacts. Each elastic connection pin is connected to an external testing device via an independent cable. After crimping, the elastic connection pins form movable elastic contacts with signal pads and solder joints, establishing a temporary electrical connection without a soldered connector. The external testing device applies an excitation signal and acquires a response signal to complete the functional test. This solution achieves a non-destructive, high-precision temporary electrical test connection for circuit boards through precise vision positioning and independent cable elastic connection, adapting to the testing needs of various circuit board specifications.

Description

Technical Field

[0001] This invention relates to the field of circuit board testing technology, and in particular to a functional testing method and test fixture for circuit boards. Background Technology

[0002] Current circuit board functional testing commonly employs soldered connectors to construct the electrical path for testing. This, combined with fixed mechanical fixtures, aligns the probes with the target interface area of ​​the circuit board. The fixture structure restricts the position of the interface connection device, and the probes are centrally connected to external testing equipment via integrated wiring harnesses. A rigid press-fit is used to achieve contact and conductivity between the probes and the pads / solder joints. The entire testing connection process relies on the soldering process and the fixed fixture. The alignment accuracy of the fixed fixture is entirely limited by manufacturing precision and assembly errors, and cannot adaptively adjust to actual positional deviations of the circuit board. The wiring harness layout can cause signal interference between adjacent probes, and the rigid contact structure is difficult to adapt to minute differences in surface flatness on the circuit board.

[0003] Soldering connectors can cause irreversible physical damage to signal pads and solder joints on circuit boards. Fixtures lack versatility and cannot adapt to the alignment requirements of target interface areas with different layouts, making it difficult to guarantee probe alignment and electrical connection stability. This invention aims to solve the problems of insufficient alignment accuracy, susceptibility to soldering damage to pads, significant signal crosstalk, and poor contact compatibility in existing testing technologies. It achieves precise alignment of interface connection devices by using image acquisition and coordinate positioning to drive a three-dimensional motion platform, and constructs a temporary, flexible electrical connection path independent of soldering connectors by using independent cables to connect elastic connecting pins. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and to propose a functional testing method and test fixture for circuit boards.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a functional testing method for a circuit board, comprising: The circuit board under test is placed at a predetermined position on the support platform, and the target interface area on the circuit board under test is image acquired and coordinate located using a visual positioning system. The target interface area includes one or more sets of signal pads and solder joints for functional testing. Based on the coordinate information obtained by the visual positioning system, the programmable three-dimensional motion platform is driven to move at least one interface connection device, so that the interface connection device is aligned with the target interface area on the circuit board under test. On the mounting surface of the interface connection device facing the circuit board under test, a plurality of elastic connection pins are arranged. Each elastic connection pin has a conductive contact at its end, and each elastic connection pin establishes an electrical path with an external test device through an independent connection cable. Driven by the programmable three-dimensional motion platform, the interface connection device is pressed against the circuit board under test, so that the conductive contacts of the multiple elastic connection pins form movable elastic contacts with the corresponding signal pads and solder joints in the target interface area, thereby establishing a temporary electrical connection path that does not depend on the soldering connector. The target interface area of ​​the circuit board under test is connected to the external test equipment via the connecting cable. The external test equipment applies test excitation signals and collects response signals to complete the functional test operation of the circuit board under test.

[0006] As a further aspect of the present invention, based on the coordinate information obtained by the visual positioning system, a programmable three-dimensional motion platform is driven to move at least one interface connection device, aligning the interface connection device with the target interface area on the circuit board under test, including: The visual positioning system extracts features from an image containing the edge and positioning holes of the circuit board under test, and calculates the offset and rotation angle of the actual placement position of the circuit board under test on the support platform from the standard position. Based on the calculated offset and rotation angle, the pre-stored standard coordinates of the target interface area are transformed to generate the spatial coordinates of the target interface area in its actual placement state. Select an interface connection device from the interface connection device library whose interface type and number of ports match the current target interface area, and load it into the execution end of the programmable three-dimensional motion platform; The spatial coordinates of the target interface area in its actual placement state are converted into motion commands for the programmable 3D motion platform. The programmable 3D motion platform is then used to move the interface connection device to directly above the target interface area and complete horizontal alignment.

[0007] As a further aspect of the present invention, under the drive of the programmable three-dimensional motion platform, the interface connection device is pressed against the circuit board under test, so that the conductive contacts of the plurality of elastic connection pins respectively form movable elastic contacts with the corresponding signal pads and solder joints in the target interface area, including: Control the programmable three-dimensional motion platform to descend vertically, so that the conductive contacts of all the elastic connecting pins on the interface connection device simultaneously contact the surface of the circuit board under test. Continue to apply the preset pressure downward, drive the interface connection device to press down as a whole, force each elastic connection pin to compress within its own elastic deformation range, and ensure that each conductive contact and the corresponding signal pad or solder point maintain a stable contact pressure. During the pressing process of the preset pressure, the contact resistance at the end of each elastic connecting pin is monitored. When all the monitored contact resistance values ​​are lower than the preset threshold, it is determined that the movable elastic contact has been stably established. While maintaining the preset pressure, the programmable three-dimensional motion platform is locked in the vertical direction to maintain the stability of the temporary electrical connection path during the test.

[0008] As a further aspect of the present invention, during the pressing process of the preset pressure, the contact resistance at the end of each of the elastic connecting pins is monitored, including: The monitoring circuit is switched sequentially to each of the aforementioned connecting cables using a multiplexer switch; After each switch, a constant micro-current test signal is applied to the currently selected connection cable through the monitoring circuit; The voltage drop generated by the micro-current test signal on the circuit formed by the conductive contact of the elastic connecting pin and the corresponding signal pad or solder joint is measured. Based on the current value of the microcurrent test signal and the measured voltage drop, the contact resistance value of the end of the elastic connecting pin is calculated. The calculated contact resistance value is recorded together with the corresponding connecting cable number and flexible connecting pin number to form a contact resistance monitoring record.

[0009] As a further aspect of the present invention, it also includes the step of disconnecting the electrical connection and retrieving the interface connection device after completing the functional test: After the external testing equipment completes all preset test items, the external testing equipment stops outputting test excitation signals; Control the programmable three-dimensional motion platform to rise vertically and remove the preset pressure applied to the interface connection device; The continuous lifting of the programmable three-dimensional motion platform causes the multiple elastic connecting pins to gradually separate from the signal pads and solder joints on the circuit board under test, and the elastic connecting pins recover to their freely extended state by their own elasticity. Once the interface connection device has completely moved away from the surface of the circuit board under test and reached a preset safe distance, the programmable three-dimensional motion platform stops moving. Based on the testing requirements of the next circuit board to be tested, the programmable three-dimensional motion platform is driven to move the interface connection device to the cleaning station or directly to the area above the next target interface.

[0010] As a further aspect of the present invention, it also includes a configuration and adaptive adjustment step for the interface connection device: When the target interface area on the circuit board under test is located on the side of the circuit board, a clip-type interface connection device is selected, and the elastic connection pin is provided on the inner side of the clamping arm of the clip-type interface connection device. When the target interface area on the circuit board under test is located in the middle of the circuit board, not at the edge, a top-press interface connection device is selected. The top-press interface connection device has the elastic connection pins vertically mounted on the support structure facing the circuit board. The clamp-type interface connector is configured with a clamping spring that matches the thickness of the circuit board, and the clamping force is set; the top-press type interface connector is configured with a compression stroke of the elastic connecting pin that matches the height of the solder pad; The selected interface connection device type and its configuration parameters, including interface type, number of ports, clamping force or compression stroke, are written into the test control program for the programmable three-dimensional motion platform to call and execute.

[0011] As a further aspect of the present invention, the interface connection device is composed of multiple independent single-port connector modules, and further includes a combination configuration step: Based on the signal definition of the target interface area, determine the total number of signal lines and signal types to be tested; Select a corresponding number and signal type of the single-port connector modules from a standardized single-port connector module library. Each single-port connector module includes an independent flexible connector pin, an independent connector cable, and an independent mechanical fixing structure. All selected single-port connector modules are arranged according to the pad layout of the target interface area, and the mechanical fixing structure of each single-port connector module is locked into a whole by a modular fixture to form a combined interface connection device customized for the current target interface area. Assign a global device identifier to the combined interface connection device and bind the cable number of each single-port connector module to the global device identifier to complete the logical configuration.

[0012] As a further aspect of the present invention, it also includes a step of using auxiliary mounting holes on the circuit board for auxiliary fixing: When the visual positioning system acquires images of the circuit board under test, it simultaneously identifies the position coordinates of the auxiliary mounting holes on the circuit board under test. On the mounting base of the interface connection device, guide posts are provided that match the positions of the auxiliary mounting holes on the circuit board under test; During the process of the programmable three-dimensional motion platform driving the interface connection device to press down, the guide post is controlled to insert into the corresponding auxiliary mounting hole to achieve horizontal positioning between the interface connection device and the circuit board under test. After the elastic connecting pin establishes elastic contact with the signal pad and solder joint, the mechanical locking between the interface connection device and the circuit board under test is achieved by screwing in the locking screw of the auxiliary mounting hole and the guide post, or by pressing down the expansion sleeve that forms an interference fit with the auxiliary mounting hole, thereby sharing part of the lateral stress borne by the elastic connecting pin.

[0013] As a further aspect of the present invention, it also includes a step of real-time verification of the electrical connection status during functional testing: During the intervals in which the external testing equipment applies the test excitation signal, an electrical connection status verification cycle is inserted. During the electrical connection status verification period, verification signals are sent to some or all of the established temporary electrical connection paths through the external testing equipment or independent monitoring circuit. Analyze the response waveform or response data of the verification signal to determine whether there are open circuits, short circuits or impedance abnormalities in each path; Record the spring connector number, signal network name, and abnormality type corresponding to the abnormal path in the test log; Based on the verification results, a decision is made on whether to continue the subsequent testing process or to trigger an alarm to prompt the operator to check the contact status between the interface connection device and the circuit board under test.

[0014] As a further aspect of the present invention, the present invention also includes a fixture for functional testing of a circuit board, applied to a functional testing method for a circuit board as described above, the fixture comprising: A visual positioning system is used to acquire images and locate coordinates of the target interface area on the circuit board under test. Programmable 3D motion platform; At least one interface connection device is driven to move by the programmable three-dimensional motion platform, the interface connection device having a mounting surface facing the circuit board under test; Multiple flexible connecting pins are disposed on the mounting surface, each of the flexible connecting pins having a conductive contact at its end, and each of the flexible connecting pins being electrically connected to an external testing device via an independent connecting cable; And clamping components, including clips for clamping electrical components on the circuit board under test; The programmable three-dimensional motion platform is configured to drive the interface connection device to move and align with the target interface area based on the coordinate information obtained by the vision positioning system, and press the interface connection device against the circuit board under test, so that the conductive contacts of the plurality of elastic connection pins form elastic contact with the corresponding signal pads and solder joints in the target interface area to establish a temporary electrical connection path.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are as follows: The vision positioning system acquires images and locates coordinates of the target interface area of ​​the circuit board under test. Based on the acquired coordinate information, it drives a programmable 3D motion platform to move the interface connection device, enabling precise alignment between the interface connection device and the target interface area. This matches the actual layout of signal pads and solder joints within the target interface area, reducing alignment deviations caused by tooling processing and assembly errors, weakening the dependence on fixed positioning tooling, improving the alignment consistency between the interface connection device and the target interface area, adapting to the alignment adjustment requirements of different layouts in the target interface area, achieving adaptive correction in the alignment process, and ensuring the alignment accuracy of conductive contacts with corresponding signal pads and solder joints.

[0016] The interface connection device has multiple flexible connection pins facing the mounting surface of the circuit board under test. Each flexible connection pin establishes an electrical path with the external test equipment through an independent connection cable. After the flexible connection pin is crimped, the conductive contact forms a movable elastic contact with the signal pads and solder joints in the target interface area, constructing a temporary electrical connection path that does not rely on soldering connectors. The independent connection cable can reduce signal crosstalk between adjacent flexible connection pins. The movable elastic contact can adapt to the slight flatness difference on the circuit board surface, maintain a stable contact state between the conductive contact and the signal pads and solder joints, avoid irreversible physical damage to the signal pads and solder joints caused by soldering operations, simplify the test connection operation process, realize the temporary construction and dismantling of the test electrical connection, and improve the flexibility and conductivity stability of the test connection. Attached Figure Description

[0017] Figure 1 This is a flowchart of a functional testing method for a circuit board according to the present invention; Figure 2 A flowchart for establishing and stabilizing elastic contacts; Figure 3 The lifting speed curve for a programmable 3D motion platform; Figure 4 A schematic diagram of the layered structure of the top-press-fit interface connection device; Figure 5 This is a thermogram showing the relationship between probe contact pressure and contact resistance. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] In the description of this invention, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0020] See Figure 1 This invention provides a method for functional testing of a circuit board, specifically including: The circuit board under test (PCB) is placed at a predetermined position on a support platform. A vision positioning system is used to acquire images and locate the target interface area on the PCB. This target interface area includes one or more sets of signal pads and solder joints for functional testing. Based on the coordinate information acquired by the vision positioning system, a programmable 3D motion platform is driven to move at least one interface connection device, aligning it with the target interface area on the PCB. Multiple flexible connector pins are arranged on the mounting surface of the interface connection device facing the PCB. Each flexible connector pin has a conductive contact at its end, and each pin establishes an electrical path with external testing equipment via an independent connecting cable. Driven by the programmable 3D motion platform, the interface connection device is pressed against the PCB, causing the conductive contacts of the multiple flexible connector pins to form movable elastic contacts with the corresponding signal pads and solder joints within the target interface area, thus establishing a temporary electrical connection path independent of soldered connectors. The target interface area of ​​the PCB is connected to the external testing equipment via connecting cables. The external testing equipment applies test excitation signals and acquires response signals, completing the functional testing operation of the PCB.

[0021] In one embodiment of the present invention, the visual positioning system extracts features from an image containing the edge and positioning holes of the circuit board under test, and calculates the offset and rotation angle between the actual placement position and the standard position of the circuit board under test on the support platform. Based on the calculated offset and rotation angle, coordinate transformation is performed on the pre-stored standard coordinates of the target interface area to generate the spatial coordinates of the target interface area in its actual placement state. An interface connection device matching the current target interface area in terms of interface type and number of ports is selected from the interface connection device library and loaded onto the execution end of the programmable three-dimensional motion platform. The spatial coordinates of the target interface area in its actual placement state are converted into motion commands for the programmable three-dimensional motion platform, controlling the programmable three-dimensional motion platform to move the interface connection device to directly above the target interface area and complete the horizontal alignment.

[0022] In practice, the vision positioning system acquires images including the edges and positioning holes of the circuit board under test and extracts features. It then calculates the offset and rotation angle between the actual placement position of the circuit board on the support platform and the standard position. Based on the calculated offset and rotation angle, it performs coordinate transformation on the pre-stored standard coordinates of the target interface area to generate the spatial coordinates of the target interface area in its actual placement state. An interface connection device matching the interface type and number of ports of the current target interface area is selected from the interface connection device library and loaded onto the execution end of the programmable 3D motion platform. The spatial coordinates of the target interface area in its actual placement state are converted into motion commands for the programmable 3D motion platform, controlling the platform to move the interface connection device directly above the target interface area and complete the horizontal alignment.

[0023] In some embodiments, the visual positioning system extracts features from an image containing the edge and positioning holes of the circuit board under test, and calculates the offset and rotation angle between the actual placement position of the circuit board on the support platform and the standard position. The calculation of the offset and rotation angle can be achieved using an image feature point matching algorithm. This algorithm identifies the coordinates of the centers of at least two non-collinear positioning holes in the image, compares them with the corresponding coordinates in the pre-stored standard position, and calculates the offset and rotation angle using a coordinate transformation model. In some embodiments, the coordinate transformation model for the offset and rotation angle can be represented by the following matrix formula:

[0024] in: and These are the standard coordinates of a point on the target interface area. and These are the spatial coordinates of the point in its actual placement state. It's the rotation angle. and It's the offset.

[0025] In practice, the standard coordinates are transformed based on the calculated offset and rotation angle to generate the spatial coordinates of the target interface area in its actual placement state. An interface connection device matching the target interface area in terms of interface type and number of ports is selected from the interface connection device library and loaded onto the execution end of the programmable 3D motion platform. The spatial coordinates of the target interface area in its actual placement state are converted into motion commands for the programmable 3D motion platform, controlling it to move the interface connection device directly above the target interface area and complete horizontal alignment. After horizontal alignment, the central axis of the interface connection device is aligned with the center of the target interface area in the plane, establishing an accurate positional reference for subsequent vertical downward pressure.

[0026] In one embodiment of the present invention, see [reference] Figure 2 The programmable 3D motion platform is controlled to descend vertically, causing the conductive contacts of all the elastic pins on the interface connection device to simultaneously contact the surface of the circuit board under test. A preset downward pressure is applied, driving the interface connection device to press down as a whole, forcing each elastic pin to compress within its own elastic deformation range, ensuring a stable contact pressure between each conductive contact and its corresponding signal pad or solder joint. During this downward pressure, the contact resistance at the end of each elastic pin is monitored. When all monitored contact resistance values ​​are below a preset threshold, it is determined that a stable movable elastic contact has been established. While maintaining this preset pressure, the programmable 3D motion platform is locked in the vertical direction to maintain the stability of the temporary electrical connection path during the test. The steps for monitoring the contact resistance at the end of each flexible connector pin include: switching the monitoring circuit sequentially to each connecting cable via a multiplexer; after each switch, applying a constant micro-current test signal to the currently selected connecting cable through the monitoring circuit; measuring the voltage drop generated by the micro-current test signal in the loop formed by the conductive contact of the flexible connector pin and the corresponding signal pad or solder joint; calculating the contact resistance value at the end of the current flexible connector pin based on the current value of the micro-current test signal and the measured voltage drop; and recording the calculated contact resistance value together with the corresponding connecting cable number and flexible connector pin number to form a contact resistance monitoring record.

[0027] In practice, the programmable 3D motion platform is controlled to descend vertically, causing the conductive contacts of all the elastic pins on the interface connection device to simultaneously contact the surface of the circuit board under test. Simultaneous contact means that the conductive contacts of all the elastic pins make initial physical contact with the circuit board surface at approximately the same moment during the single vertical displacement of the programmable 3D motion platform. A preset downward pressure is then applied, driving the interface connection device to press down as a whole, forcing each elastic pin to compress within its own elastic deformation range, ensuring a stable contact pressure between each conductive contact and its corresponding signal pad or solder joint. During the downward pressure, the contact resistance at the end of each elastic pin is monitored. When all monitored contact resistance values ​​are below a preset threshold, it is determined that a stable elastic contact has been established. While maintaining the preset pressure, the programmable 3D motion platform is locked in the vertical direction to maintain the stability of the temporary electrical connection path during the test.

[0028] In practice, monitoring the contact resistance at the end of each flexible connector pin is achieved through a specially configured monitoring circuit and a multiplexer. The multiplexer sequentially switches the monitoring circuit to each connecting cable, which is an independent wire connecting each flexible connector pin to an external test device or the backplane of the monitoring circuit. After each switch, a constant micro-current test signal is applied to the currently selected connecting cable through the monitoring circuit, and the voltage drop generated by the micro-current test signal in the loop formed by the conductive contact of the flexible connector pin and the corresponding signal pad or solder joint is measured. Based on the current value of the micro-current test signal and the measured voltage drop, the contact resistance value at the end of the current flexible connector pin is calculated. The calculation of the contact resistance value follows Ohm's law, and its formula is expressed as:

[0029] in: This represents the calculated contact resistance value at the end of a single elastic connecting pin. This represents the measured voltage drop. This indicates the current value of the constant microcurrent test signal applied by the monitoring circuit.

[0030] In practice, the monitoring circuit is a combination of a constant current source and a high-precision voltage measurement module. The multiplexer is a semiconductor analog switch array, sequentially selected by a control signal. During each measurement, the constant current source outputs a known constant current to the selected connecting cable and the test circuit formed by it. The high-precision voltage measurement module simultaneously measures the voltage between the conductive contacts and the pad contacts on this circuit. It is understandable that the calculated contact resistance value... The calculation includes not only the ideal metal-to-metal contact resistance but also the wire resistance of the connecting cable. However, the wire resistance is a known fixed value and can be subtracted from the calculation result through software calibration to obtain a pure contact resistance. The calculated contact resistance value is recorded together with the corresponding connecting cable number and flexible pin number to form a contact resistance monitoring record. The contact resistance monitoring record is a data structure containing a timestamp, connecting cable identifier, flexible pin identifier, measured contact resistance value, and a preset pass threshold. In some embodiments, the preset threshold is an upper limit set based on the signal integrity and electrical safety requirements of the circuit board test, such as 50 milliohms. When all monitored contact resistance values ​​are below this preset threshold, the system determines that a stable, low-impedance flexible contact has been established and can proceed to the functional testing phase. Locking the programmable 3D motion platform in the vertical direction is typically achieved by enabling the servo motor's brake or locking the linear motor's mechanical brake, thereby maintaining a constant downward pressure position of the interface connection device during testing, thus maintaining a constant compression amount of the flexible pin, and ultimately maintaining the resistance stability of the temporary electrical connection path.

[0031] In some embodiments, the preset pressure is achieved by controlling the driving force of a vertical axis servo motor or cylinder of a programmable three-dimensional motion platform. The pressure value can be preset according to the material of the elastic connecting pin, the spring constant, and the desired compression stroke, and configured in the motion control program as a position-force hybrid control mode. During the monitoring of contact resistance, the monitoring circuit traverses all connecting cables in a cyclic scanning manner, with each scan being called a monitoring cycle. Optionally, multiple monitoring cycles can be executed during a single pressure and contact establishment process, and the data from each cycle can be recorded for trend analysis to ensure the stability of the contact resistance rather than just achieving the target in a single measurement.

[0032] In one embodiment of the present invention, after the external testing equipment completes all preset test items, the external testing equipment stops outputting test excitation signals. The programmable three-dimensional motion platform is controlled to rise vertically, and the preset pressure applied to the interface connection device is removed. The continuous rising of the programmable three-dimensional motion platform causes multiple elastic connection pins to gradually separate from the signal pads and solder joints on the circuit board under test, and the elastic connection pins recover to their freely extended state due to their own elasticity. When the interface connection device completely leaves the surface of the circuit board under test and reaches a preset safe distance, the programmable three-dimensional motion platform stops moving. According to the test requirements of the next circuit board under test, the programmable three-dimensional motion platform is driven to move the interface connection device to the cleaning station or directly to above the next target interface area.

[0033] In practice, after the external testing equipment completes all preset test items, it stops outputting test excitation signals. The programmable 3D motion platform is then raised vertically, releasing the preset pressure applied to the interface connector. The continuous raising of the programmable 3D motion platform causes multiple elastic connector pins to gradually separate from the signal pads and solder joints on the circuit board under test (TBT). The elastic connector pins then recover to their freely extended state due to their own elasticity. When the interface connector completely leaves the TBT surface and reaches a preset safe distance, the programmable 3D motion platform stops. This preset safe distance is a pre-set vertical gap that ensures the interface connector will not accidentally collide with the TBT under any movement. Based on the testing requirements of the next TBT circuit board, the programmable 3D motion platform is driven to move the interface connector to the cleaning station or directly above the next target interface area. In some embodiments, the cleaning station is a separate location in the system, equipped with a cleaning solvent nozzle and compressed air nozzle, used to automatically clean the conductive contacts of the elastic connector pins, removing any flux or oxides that may remain after multiple contacts.

[0034] In practical implementation, external testing equipment stops outputting test excitation signals, including stopping the output of all digital signals, analog signals, power supplies, and specific clock signals, and placing all output ports in a high-impedance or safe state. The control of the programmable 3D motion platform's vertical lifting motion has a set lifting speed curve, and the lifting speed... The lifting motion can be determined based on the quality of the interface connection device, the elastic coefficient of the flexible connecting pin, and the requirement to avoid excessive inertial impact. Begin by raising the equipment to the height corresponding to the preset safe distance. End, total lifting distance It can be calculated using the following formula:

[0035] in: This indicates the height coordinates corresponding to the preset safety distance. This indicates the height coordinates at which the interface connection device is locked during testing. This indicates the total lifting distance.

[0036] In practice, the continuous lifting motion of the programmable 3D motion platform is precisely controlled by a controller. The separation of the elastic connector pin is a gradual process. At the moment of separation, a tiny electric arc may be generated between the conductive contact of the elastic connector pin and the pad, but the arc energy is controlled within a safe range because the external test equipment signal has stopped. The elastic connector pin recovers to its free extension state due to its own elasticity. The free extension state refers to the natural length state of the elastic connector pin when it is not subjected to any external compressive force. When the interface connection device completely leaves the surface of the circuit board under test and reaches the preset safe distance, the programmable 3D motion platform stops moving. Stopping moving means that the servo motor stops supplying power and may enter the position holding mode. It can be understood that the determination of whether the preset safe distance has been reached is achieved by comparing the position information fed back by the high-precision encoder installed on the programmable 3D motion platform with the preset position threshold. According to the test requirements of the next circuit board under test, the programmable 3D motion platform is driven to move the interface connection device to the cleaning station or directly to the area above the next target interface. This decision logic can be automatically made based on the pre-programmed test sequence or the real-time detected contact cleanliness. In some embodiments, the system maintains an interface connection device usage record table, which records the number of times each interface connection device has been tested and the number of times it has been used since the last cleaning. When the number of uses exceeds a preset threshold, the system instructs the programmable 3D motion platform to send the interface connection device to the cleaning station for cleaning after completing the test. Optionally, the preset threshold can be configured according to the cleanliness of the solder pads on the circuit board under test, the test environment, and reliability requirements. See Table 1.

[0037] Table 1: Interface Connection Device Usage and Maintenance Record Interface connection device identification Total number of uses Total number of uses after this test Cleaning status ProbeHead_01 1500 12 Cleaning required ProbeHead_02 980 5 normal ClampType_A 750 3 normal In practice, Table 1 records the usage and maintenance information of the interface connection device. The interface connection device identifier is a unique identification number. The total number of uses is the cumulative number of tests since the device was put into use. The cumulative number of uses after this test is the number of tests completed since the last cleaning or maintenance. The cleaning status is a status indication derived by comparing a preset cleaning threshold with the "cumulative number of uses after this test." When the "cumulative number of uses after this test" reaches the preset cleaning threshold, the cleaning status is marked as "needs cleaning," and the system will drive the programmable 3D motion platform to send the interface connection device to the cleaning station after disconnection. At the cleaning station, the interface connection device will be cleaned according to a preset procedure. After cleaning, the "cumulative number of uses after this test" will be reset to zero, and the cleaning status will be updated to "normal." If cleaning is not required, the programmable 3D motion platform will directly carry the interface connection device to the next target position for alignment according to the test procedure of the next circuit board under test, thus skipping the cleaning step and saving overall test cycle time.

[0038] See Figure 3 The lifting speed curve of the programmable 3D motion platform follows a symmetrical S-shaped smooth speed change design, aiming to achieve smooth separation of the interface connection device and the circuit board under test after testing. The curve, with time as the horizontal axis and lifting speed (mm / s) as the vertical axis, fully covers the lifting cycle from 0 to 2.00 s: Acceleration phase (0~1.00 s): The speed smoothly increases from 0 mm / s to a peak of approximately 15 mm / s, with acceleration gradually increasing and then decreasing to avoid inertial impact during the initial stage and protect the elastic connector pins and the circuit board pads from mechanical stress damage. Constant speed / gradual descent phase (approximately 1.00 s): The speed is maintained near the peak for a brief transition, providing a smooth transition for the subsequent deceleration and ensuring stable platform motion. Deceleration phase (1.00 s~2.00 s): The speed symmetrically decreases to 0 mm / s, with the deceleration change mirroring the acceleration phase, ensuring precise locking at the lifting endpoint, avoiding overshoot or vibration, and simultaneously allowing the elastic connector pins to gradually detach from the pads, suppressing arcing and contact wear at the moment of separation. The speed curve design fully considers the quality of the interface connection device, the elastic coefficient of the elastic connection pin, and the impact resistance requirements of the system. Through a smooth speed change strategy, it achieves a lifting action with low vibration and low stress, which not only ensures the safe disconnection of the temporary electrical connection path, but also provides a stable motion basis for the subsequent cleaning or reuse of the interface connection device.

[0039] In one embodiment of the present invention, when the target interface area on the circuit board under test is located on the side of the circuit board, a clip-type interface connection device is selected, wherein the clamping arm of the clip-type interface connection device is provided with elastic connecting pins on its inner side. When the target interface area on the circuit board under test is located in the middle of the circuit board, not at the edge, a top-press type interface connection device is selected, wherein the top-press type interface connection device has elastic connecting pins vertically mounted on the support structure facing the circuit board. A clamping spring matching the thickness of the circuit board is configured for the clip-type interface connection device, and the clamping force is set. The compression stroke of the elastic connecting pins matching the height of the pads is configured for the top-press type interface connection device. The selected interface connection device type and its configuration parameters, including interface type, number of ports, clamping force or compression stroke, are written into the test control program for execution by the programmable three-dimensional motion platform. The interface connection device can be composed of multiple independent single-port connector modules. The combination configuration steps include: determining the total number and signal types of signal lines to be tested according to the signal definition of the target interface area; selecting the corresponding number and signal types of single-port connector modules from a standardized single-port connector module library; each single-port connector module contains an independent elastic connector pin, an independent connector cable, and an independent mechanical fixing structure; arranging all selected single-port connector modules according to the pad layout of the target interface area; and locking the mechanical fixing structure of each single-port connector module into a whole using a modular fixture to form a combined interface connection device customized for the current target interface area; assigning a global device identifier to the combined interface connection device; and binding the cable number of each single-port connector module to the global device identifier to complete the logical configuration.

[0040] In practical implementation, when the target interface area on the circuit board under test is located on the side of the circuit board, a clip-type interface connection device is selected. The clip-type interface connection device has elastic connecting pins on the inner side of its clamping arm. When the target interface area on the circuit board under test is located in the middle, not at the edge, a top-press type interface connection device is selected. The top-press type interface connection device has elastic connecting pins vertically mounted on the support structure facing the circuit board. A clamping spring matching the circuit board thickness is configured for the clip-type interface connection device, and the clamping force is set. The compression stroke of the elastic connecting pins matching the pad height is configured for the top-press type interface connection device. It can be understood that the clamping spring is the elastic element providing the clamping force, while the compression stroke is the maximum linear displacement allowed for the elastic connecting pin from a free state to full compression in the top-press type. The selected interface connection device type and its configuration parameters, including interface type, number of ports, clamping force, or compression stroke, are written into the test control program for execution by the programmable 3D motion platform. The interface connection device is composed of multiple independent single-port connector modules. The assembly configuration steps determine the total number and signal types of signal lines to be tested based on the signal definition of the target interface area. A corresponding number and signal types of single-port connector modules are selected from a standardized single-port connector module library. Each single-port connector module contains an independent flexible connector pin, an independent connector cable, and an independent mechanical fixing structure. All selected single-port connector modules are arranged according to the pad layout of the target interface area, and the mechanical fixing structures of each single-port connector module are locked together as a whole using modular fixtures, forming a combined interface connection device customized for the current target interface area. A global device identifier is assigned to the combined interface connection device, and the cable number of each single-port connector module is bound to the global device identifier to complete the logical configuration.

[0041] In practical implementation, interface type identification and selection are based on the analysis of visual images of the target interface area. It can be understood that interface types may include standard or non-standard interfaces such as USB Type-C, HDMI, and board-to-board connector pad arrays. Clip-type interface connection devices are suitable for gold fingers or side test points on the edge of the circuit board, with clamping force... The setting needs to ensure sufficient contact pressure without damaging the circuit board edges, and the clamping force... With circuit board thickness and the spring constant The basic relationship between them can be expressed as:

[0042] in: This indicates the set clamping force. Indicates the number of clamping springs. This indicates the spring constant of a single clamping spring. This indicates the opening distance of a clip-type interface connection device in its free state. This indicates the thickness of the circuit board under test. The top-press interface connection is suitable for pad arrays on the circuit board surface, with a compression stroke. The configuration must ensure that the resilient connector pin generates sufficient compression upon contact with the pad to provide stable contact force, while not exceeding its maximum permissible stroke to avoid permanent deformation. In some embodiments, the compression stroke... It is usually set to be slightly larger than the height difference between the highest and lowest points on the pad array. With a basic compression margin The sum of The basic compression margin These are preset empirical values ​​used to compensate for manufacturing tolerances and positioning errors. See Table 2.

[0043] Table 2: Configuration Parameters of Interface Connection Device Target interface area location Select interface connection device form Key configuration parameters Parameter value Number of single-port connector modules used Side of the circuit board (gold fingers) clip form Clamping force 15N 24 Middle of the circuit board (BGA solder ball array) Top crimp form Compressed travel 1.5mm 256 Middle section of the circuit board (test point cluster) Top crimping Compressed travel 2.0mm 48 In practical implementation, Table 2 shows the configuration options for different target interface areas. When the target interface area is the gold fingers located on the side of the circuit board, a clip-type interface connection device is selected, with a clamping force of 15 Newtons, and 24 single-port connector modules are used. When the target interface area is the BGA solder ball array located in the middle of the circuit board, a top-press interface connection device is selected, with a compression stroke of 1.5 mm set according to the solder ball height difference, and 256 single-port connector modules are used to form a high-density probe array. These configuration parameters, including the interface connection device type, clamping force, compression stroke, and the number of single-port connector modules used, are written as a configuration record into the test control program. Optionally, the test control program is a software program stored in the test system's main control computer, which contains the test process definition and corresponding hardware configuration parameters for different circuit board models. A corresponding number and signal type of single-port connector modules are selected from a standardized single-port connector module library. The single-port connector module library is a physical module storage rack, and each module has a unique RFID tag identifying its electrical characteristics, such as signal type (digital input, digital output, analog input, analog output, power, or ground). All selected single-port connector modules are arranged according to the pad layout of the target interface area. This arrangement can be done manually or automatically on an assembly platform with a positioning grid, ensuring that the elastic connecting pins of each single-port connector module are aligned with the target pads. The mechanical fixing structure of each single-port connector module is locked into a single unit using a modular fixture, a mechanical frame with adjustable slots and locking screws. A global device identifier, such as "Combined_Probe_Unit_001," is assigned to the combined interface connection device. The cable numbers of each single-port connector module, such as "Cable_A01" and "Cable_A02," are bound to the global device identifier "Combined_Probe_Unit_001" in the system configuration database, completing the logical configuration. This allows external test equipment to correctly address and control each test signal channel during subsequent testing through the mapping relationship between the global device identifier and the cable number.

[0044] See Figure 4In the structural design of the top-pressed interface connection device, its layered layout and compatibility with the pad array in the middle of the circuit board are clearly demonstrated. The device consists of three layers: a pressing base, an elastic probe array, and a test area in the middle of the circuit board. Each component forms a clear functional zone in the vertical direction: Pressing base (dark gray area): Serving as the mechanical support and mounting base, covering the range of horizontal coordinates 2 to 6 and vertical coordinates 5 to 6, providing stable mechanical support and mounting reference for the elastic probes, while also limiting the upper limit of the overall pressing stroke. Elastic probes (red area): Arranged in a discrete array below the pressing base, within the range of horizontal coordinates 3 to 6 and vertical coordinates 3 to 5. Their free extension height and compression stroke match the height difference of the pads in the middle of the circuit board, ensuring stable contact pressure through elastic deformation during pressing and avoiding pad damage. Middle of the circuit board (blue area): Serving as the load-bearing area for the test object, covering the range of horizontal coordinates 1 to 7 and vertical coordinates 1 to 3, corresponding to the pad array in the middle of the circuit board under test, providing a precise contact reference surface for the elastic probes. The layered structure decouples the mechanical support, elastic contact, and test object functions. Through vertical spatial allocation, it ensures precise alignment and stable contact between the probe and the pad in the top-press form, making it suitable for testing high-density pad arrays in the non-edge areas of the circuit board.

[0045] In one embodiment of the present invention, when the vision positioning system acquires images of the circuit board under test, it simultaneously identifies the position coordinates of the auxiliary mounting holes on the circuit board under test. A guide post, matching the position of the auxiliary mounting hole on the circuit board under test, is provided on the mounting base of the interface connection device. During the downward pressing process of the interface connection device driven by the programmable three-dimensional motion platform, the guide post is controlled to insert into the corresponding auxiliary mounting hole, achieving horizontal limiting between the interface connection device and the circuit board under test. After the elastic connecting pin establishes elastic contact with the signal pads and solder joints, mechanical locking between the interface connection device and the circuit board under test is achieved by screwing in the locking screw between the auxiliary mounting hole and the guide post, or by pressing down the expansion sleeve that forms an interference fit with the auxiliary mounting hole, thus sharing some of the lateral stress borne by the elastic connecting pin. The steps for real-time verification of electrical connection status during functional testing include: inserting an electrical connection status verification cycle during the intervals when test excitation signals are applied by external test equipment; sending verification signals to some or all of the established temporary electrical connection paths through external test equipment or independent monitoring circuits within the verification cycle; analyzing the response waveform or response data of the verification signals; determining whether there are open circuits, short circuits, or impedance abnormalities in each path; recording the elastic connection pin number, signal network name, and abnormality type corresponding to the abnormal path in the test log; and deciding whether to continue the subsequent test process or trigger an alarm to prompt the operator to check the contact status between the interface connection device and the circuit board under test based on the verification results.

[0046] In practical implementation, while the vision positioning system acquires images of the circuit board under test, it simultaneously identifies the position coordinates of the auxiliary mounting holes on the circuit board. Guide posts matching the positions of the auxiliary mounting holes on the circuit board are set on the mounting base of the interface connection device. During the downward pressing process of the interface connection device driven by the programmable 3D motion platform, the guide posts are controlled to insert into the corresponding auxiliary mounting holes, achieving horizontal limiting between the interface connection device and the circuit board under test. After the elastic connecting pins establish elastic contact with the signal pads and solder joints, mechanical locking between the interface connection device and the circuit board under test is achieved by screwing in the locking screws of the auxiliary mounting holes and guide posts, or by pressing down the expansion sleeve that forms an interference fit with the auxiliary mounting holes, thus sharing some of the lateral stress borne by the elastic connecting pins. The step of real-time verification of the electrical connection status during functional testing includes inserting an electrical connection status verification cycle during the intervals between the application of test excitation signals by external test equipment. During the electrical connection status verification cycle, verification signals are sent to some or all of the established temporary electrical connection paths through external test equipment or independent monitoring circuits. The response waveforms or response data of the verification signals are analyzed to determine whether there are open circuits, short circuits, or impedance abnormalities in each path. Record the spring connector pin number, signal network name, and anomaly type corresponding to any abnormal path in the test log. Based on the verification results, decide whether to continue the subsequent testing process or trigger an alarm to prompt the operator to check the contact status between the interface connection device and the circuit board under test.

[0047] In some embodiments, the visual positioning system simultaneously identifies the position coordinates of auxiliary mounting holes on the circuit board under test. These auxiliary mounting holes are through holes or threaded holes on the circuit board specifically used for mechanical positioning or fixing, in addition to pads and solder joints used for electrical connections. The identification process includes locating the center of the auxiliary mounting hole in the acquired image and calculating its coordinates in the coordinate system of the support platform. Guide posts are provided on the mounting base of the interface connection device. The mounting base is a mechanical component that fixes the main structure of the interface connection device, and the guide posts are precision-machined cylindrical or tapered pins. The position coordinates of the guide posts are... Target coordinates of auxiliary mounting holes The two must satisfy a positional matching relationship, and their matching error must be within a certain range. It must be smaller than the allowable tolerance range. Matching error It can be represented as:

[0048] in: This represents the spatial coordinate vector of the guide post at its designed location. This represents the spatial coordinate vector of the center of the auxiliary mounting hole identified by the visual positioning system. This represents the coordinate transformation matrix from the coordinate system of the bearing platform to the coordinate system of the mounting base of the interface connection device. This represents the magnitude of the vector. During the downward pressing process of the programmable 3D motion platform drive interface connection device, the tip of the guide post is designed with a chamfer to assist the guide post in smoothly entering the auxiliary mounting hole. After the guide post is fully inserted into the auxiliary mounting hole, the relative displacement of the interface connection device and the circuit board under test in the horizontal direction is strictly limited, achieving horizontal limiting. After the elastic connection pin establishes stable elastic contact with the signal pads and solder joints, the optional mechanical locking methods include screwing in a locking screw or pressing down an expansion sleeve. When using a locking screw, the guide post has a hollow structure with internal threads. The locking screw passes through the mounting base of the interface connection device and is screwed into the threaded hole of the guide post until the screw head presses against the surface of the circuit board or the mounting base, generating a locking force. When using an expansion sleeve, the guide post has a segmented elastic structure with an external conical sleeve. Pressing down the conical sleeve forces the segmented structure of the guide post to expand radially, forming an interference fit friction with the inner wall of the auxiliary mounting hole, achieving locking. The purpose of mechanical locking is to share the lateral stress that the elastic connecting pin may bear during the test due to vibration, cable pulling or thermal expansion and contraction, and to prevent the contact point from sliding or breaking due to lateral force.

[0049] During functional testing, the electrical connection status is verified in real time. In practice, the electrical connection status verification period is a short time interval inserted between the formal functional test excitation signals, specifically for checking the path connection quality. During the electrical connection status verification period, external test equipment or an independent monitoring circuit sends a verification signal to a selected temporary electrical connection path. This verification signal is a low-frequency, low-voltage, low-current probe signal, distinct from the functional test excitation signal; for example, a square wave or sine wave with a fixed amplitude and frequency. The path status is determined by analyzing the response waveform or response data of the verification signal. For the case of sending a square wave verification signal, the rise time of the received signal can be measured. descent time The presence of signal reflection is used to assess the continuity of the path impedance. In the case of an open circuit, the receiver will not detect a valid signal. In the case of a short circuit, the receiver signal will exhibit a continuous DC level. The spring connector number, signal network name, and anomaly type corresponding to the abnormal path are recorded in the test log. The test log is a file that records events and data throughout the entire test process. The anomaly type can be "open circuit," "short circuit to ground," "short circuit to power supply," or "high impedance." In some embodiments, the decision to continue subsequent test procedures is based on the number and criticality of the abnormal paths. If the abnormal path exists only at non-critical test points, the test control program may choose to skip the relevant test items and continue execution. If the abnormal path exists on a critical power or clock network, the test control program will immediately pause the test and trigger an audible and visual alarm. Simultaneously, the operator will be prompted on the human-machine interface to check the contact status of the specific interface connection device and the circuit board under test, for example, prompting "Channel A15 (Network: CLK_50M) open circuit, please check the contact of probe number 15." Optionally, after an alarm is triggered, the system can automatically control the programmable three-dimensional motion platform to slightly lift the interface connection device and then re-execute the alignment and pressing contact process to attempt to automatically restore the connection. If the automatic restoration fails, the operator will be notified to intervene.

[0050] See Figure 5 In the heatmap of the relationship between probe contact pressure and contact resistance, the data point density is visually presented through a color gradient. The high-density red area reflects the stable and reliable electrical contact range under typical operating conditions. The "×" marked in the figure represents an abnormal channel, where the corresponding contact pressure and contact resistance combination deviates from the main data distribution cluster: the abnormal point on the left is located at a contact pressure of approximately 0.81 N and a contact resistance of approximately 20.5 mΩ. The overall data density in this area is low, indicating a risk of contact instability or high impedance under low pressure; the abnormal point on the right is located at a contact pressure of approximately 1.15 N and a contact resistance of approximately 17.8 mΩ. Although it is in a higher pressure range, it still deviates from the main density band, possibly due to localized failures such as probe tip contamination, pad oxidation, or mechanical misalignment. The main density band of the heatmap is concentrated in the range of contact pressure 0.80–1.20 N and contact resistance 15–33 mΩ, showing a general decreasing trend in contact resistance as contact pressure increases, consistent with the classic mechanical-electrical coupling characteristics of elastic probes' "pressure-contact resistance". This diagram can be directly used to guide the setting of the preset pressure threshold in functional testing: prioritize the pressure range within the main density band (e.g., 1.0–1.1N) to balance contact stability and the mechanical fatigue life of the probe / pad; at the same time, incorporate the impedance threshold corresponding to the abnormal channel into the real-time verification logic, and quickly trigger contact status re-inspection or alarm when the resistance of a certain channel deviates from the main distribution cluster.

[0051] This invention provides a functional test fixture for circuit boards, which aims to enable rapid, reliable, and non-invasive functional testing of circuit boards without connectors or where it is inconvenient to solder connectors.

[0052] In some embodiments, the functional test fixture for the circuit board includes a support platform, a vision positioning system, a programmable three-dimensional motion platform, at least one interface connection device, multiple flexible connecting pins, and clamping components.

[0053] The support platform is typically made of engineering plastic with anti-static properties or metal material with an insulating coating. It features limiting edges or positioning pins for initial positioning of the circuit board under test, ensuring consistent initial placement. Vacuum adsorption channels may be integrated beneath the platform, allowing the circuit board to be stably adsorbed and fixed onto the platform via an external vacuum generator, preventing displacement during testing.

[0054] The vision positioning system preferably includes an industrial camera fixed above the support platform, equipped with a ring light source. The camera photographs the circuit board under test placed at a predetermined position on the support platform, and uses image processing algorithms (such as template matching and feature point recognition) to accurately identify the target interface area on the circuit board. The target interface area is typically one or more sets of exposed signal pads and solder joints on the surface of the circuit board. The vision positioning system calculates the precise center coordinates and angular deflection information of the target interface area in the fixture coordinate system and transmits this information to the control system.

[0055] The programmable three-dimensional motion platform can be a combination of a three-axis (X, Y, Z) linear motor module, a servo motor-driven ball screw module, or a high-precision linear motor platform, and is controlled by a control system (such as a PLC). The interface connection device is rigidly mounted on the Z-axis end of the three-dimensional motion platform via a connecting block. The mounting surface of the interface connection device is made of insulating material, and multiple mounting holes are formed on it in a matrix or specific array according to the pad layout of the interface area of ​​the target to be tested.

[0056] The flexible connecting pins are installed within the mounting holes. Each flexible connecting pin has a core of a miniature spring probe (Pogo Pin), with a hemispherical or crown-shaped conductive contact at its end, made of gold-plated beryllium copper or piano wire, providing excellent conductivity and wear resistance. The main body of the spring probe is housed within an insulating sleeve, ensuring insulation between probes. The tail end of each spring probe is connected to an independent flexible connecting cable via welding or crimping. All cables are bundled together and connected to external testing equipment (such as the signal interface card of an automated test unit, ATE).

[0057] The clamping assembly is a key component of the fixture of this invention. It is primarily used to assist in securing soldered electrical components (such as large capacitors, inductors, shielding covers, or easily loosened connectors) on the circuit board under test before and during testing, preventing stress or displacement of solder joints due to their own weight or testing vibrations. The clamping assembly includes one or more mechanical clamps, which can be independently mounted on columns or adjustable brackets at the edge of the support platform. The front end of the clamp arms is covered with an insulating silicone sleeve, and the clamping force can be adjusted by its built-in torsion spring or miniature cylinder, ensuring secure clamping of the electrical components without damaging the component body or the circuit board.

[0058] During testing, the operator first places the circuit board under test (PCB) on the support platform and secures it using vacuum adsorption. Then, the control system initiates a vision positioning process to obtain the precise location of the target interface area. Next, the programmable 3D motion platform, based on this location information, drives the interface connection device to move directly above the target interface area and precisely align it. Afterward, the Z-axis moves downward, smoothly pressing the interface connection device against the PCB. During this process, the conductive contacts of multiple elastic connector pins press against the corresponding signal pads under the action of springs, forming multi-point, reliable elastic contact with a small margin of movement, establishing a temporary electrical connection path. Simultaneously, the operator can use the clamps on the clamping assembly to further clamp and secure critical electrical components on the PCB. Finally, external testing equipment applies test signals to the PCB through the connecting cables and the established electrical connection path and collects the response, completing the functional test. After the test, the motion platform lifts and resets the interface connection device, the elastic connector pins separate from the PCB, the clamping assembly releases, and the PCB can be removed. The entire process requires no soldering of any connectors, achieving efficient and non-destructive testing of the PCB.

[0059] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for functional testing of a circuit board, characterized in that, The method includes: The circuit board under test is placed at a predetermined position on the support platform, and the target interface area on the circuit board under test is image acquired and coordinate located using a visual positioning system. The target interface area includes one or more sets of signal pads and solder joints for functional testing. Based on the coordinate information obtained by the visual positioning system, the programmable three-dimensional motion platform is driven to move at least one interface connection device, so that the interface connection device is aligned with the target interface area on the circuit board under test. On the mounting surface of the interface connection device facing the circuit board under test, a plurality of elastic connection pins are arranged. Each elastic connection pin has a conductive contact at its end, and each elastic connection pin establishes an electrical path with an external test device through an independent connection cable. Driven by the programmable three-dimensional motion platform, the interface connection device is pressed against the circuit board under test, so that the conductive contacts of the multiple elastic connection pins form movable elastic contacts with the corresponding signal pads and solder joints in the target interface area, thereby establishing a temporary electrical connection path that does not depend on the soldering connector. The target interface area of ​​the circuit board under test is connected to the external test equipment via the connecting cable. The external test equipment applies test excitation signals and collects response signals to complete the functional test operation of the circuit board under test.

2. The functional testing method for a circuit board according to claim 1, characterized in that, Based on the coordinate information obtained by the visual positioning system, a programmable 3D motion platform is driven to move at least one interface connection device, aligning the interface connection device with the target interface area on the circuit board under test, including: The visual positioning system extracts features from an image containing the edge and positioning holes of the circuit board under test, and calculates the offset and rotation angle of the actual placement position of the circuit board under test on the support platform from the standard position. Based on the calculated offset and rotation angle, the pre-stored standard coordinates of the target interface area are transformed to generate the spatial coordinates of the target interface area in its actual placement state. Select an interface connection device from the interface connection device library whose interface type and number of ports match the current target interface area, and load it into the execution end of the programmable three-dimensional motion platform; The spatial coordinates of the target interface area in its actual placement state are converted into motion commands for the programmable 3D motion platform. The programmable 3D motion platform is then used to move the interface connection device to directly above the target interface area and complete horizontal alignment.

3. The functional testing method for a circuit board according to claim 2, characterized in that, Driven by the programmable three-dimensional motion platform, the interface connection device is pressed against the circuit board under test, so that the conductive contacts of the plurality of elastic connection pins respectively form movable elastic contacts with the corresponding signal pads and solder joints in the target interface area, including: Control the programmable three-dimensional motion platform to descend vertically, so that the conductive contacts of all the elastic connecting pins on the interface connection device simultaneously contact the surface of the circuit board under test. Continue to apply the preset pressure downward, drive the interface connection device to press down as a whole, force each elastic connection pin to compress within its own elastic deformation range, and ensure that each conductive contact and the corresponding signal pad or solder point maintain a stable contact pressure. During the pressing process of the preset pressure, the contact resistance at the end of each elastic connecting pin is monitored. When all the monitored contact resistance values ​​are lower than the preset threshold, it is determined that the movable elastic contact has been stably established. While maintaining the preset pressure, the programmable three-dimensional motion platform is locked in the vertical direction to maintain the stability of the temporary electrical connection path during the test.

4. The functional testing method for a circuit board according to claim 3, characterized in that, During the pressing process of the preset pressure, the contact resistance at the end of each elastic connecting pin is monitored, including: The monitoring circuit is switched sequentially to each of the aforementioned connecting cables using a multiplexer switch; After each switch, a constant micro-current test signal is applied to the currently selected connection cable through the monitoring circuit; The voltage drop generated by the micro-current test signal on the circuit formed by the conductive contact of the elastic connecting pin and the corresponding signal pad or solder joint is measured. Based on the current value of the microcurrent test signal and the measured voltage drop, the contact resistance value of the end of the elastic connecting pin is calculated. The calculated contact resistance value is recorded together with the corresponding connecting cable number and flexible connecting pin number to form a contact resistance monitoring record.

5. The functional testing method for a circuit board according to claim 4, characterized in that, It also includes the steps of disconnecting the electrical connection and retrieving the interface connection device after completing the functional test: After the external testing equipment completes all preset test items, the external testing equipment stops outputting test excitation signals; Control the programmable three-dimensional motion platform to rise vertically and remove the preset pressure applied to the interface connection device; The continuous lifting of the programmable three-dimensional motion platform causes the multiple elastic connecting pins to gradually separate from the signal pads and solder joints on the circuit board under test, and the elastic connecting pins recover to their freely extended state by their own elasticity. Once the interface connection device has completely moved away from the surface of the circuit board under test and reached a preset safe distance, the programmable three-dimensional motion platform stops moving. Based on the testing requirements of the next circuit board to be tested, the programmable three-dimensional motion platform is driven to move the interface connection device to the cleaning station or directly to the area above the next target interface.

6. The functional testing method for a circuit board according to claim 5, characterized in that, It also includes the configuration and adaptation steps for the interface connection device: When the target interface area on the circuit board under test is located on the side of the circuit board, a clip-type interface connection device is selected, and the elastic connection pin is provided on the inner side of the clamping arm of the clip-type interface connection device. When the target interface area on the circuit board under test is located in the middle of the circuit board, not at the edge, a top-press interface connection device is selected. The top-press interface connection device has the elastic connection pins vertically mounted on the support structure facing the circuit board. The clamp-type interface connector is configured with a clamping spring that matches the thickness of the circuit board, and the clamping force is set; the top-press type interface connector is configured with a compression stroke of the elastic connecting pin that matches the height of the solder pad; The selected interface connection device type and its configuration parameters, including interface type, number of ports, clamping force or compression stroke, are written into the test control program for the programmable three-dimensional motion platform to call and execute.

7. The method for functional testing of a circuit board according to claim 6, characterized in that, The interface connection device is composed of multiple independent single-port connector modules, and also includes a combination configuration step: Based on the signal definition of the target interface area, determine the total number of signal lines and signal types to be tested; Select a corresponding number and signal type of the single-port connector modules from a standardized single-port connector module library. Each single-port connector module includes an independent flexible connector pin, an independent connector cable, and an independent mechanical fixing structure. All selected single-port connector modules are arranged according to the pad layout of the target interface area, and the mechanical fixing structure of each single-port connector module is locked into a whole by a modular fixture to form a combined interface connection device customized for the current target interface area. Assign a global device identifier to the combined interface connection device and bind the cable number of each single-port connector module to the global device identifier to complete the logical configuration.

8. The functional testing method for a circuit board according to claim 7, characterized in that, It also includes a step of using auxiliary mounting holes on the circuit board for auxiliary fixing: When the visual positioning system acquires images of the circuit board under test, it simultaneously identifies the position coordinates of the auxiliary mounting holes on the circuit board under test. On the mounting base of the interface connection device, guide posts are provided that match the positions of the auxiliary mounting holes on the circuit board under test; During the process of the programmable three-dimensional motion platform driving the interface connection device to press down, the guide post is controlled to insert into the corresponding auxiliary mounting hole to achieve horizontal positioning between the interface connection device and the circuit board under test. After the elastic connecting pin establishes elastic contact with the signal pad and solder joint, the mechanical locking between the interface connection device and the circuit board under test is achieved by screwing in the locking screw of the auxiliary mounting hole and the guide post, or by pressing down the expansion sleeve that forms an interference fit with the auxiliary mounting hole, thereby sharing part of the lateral stress borne by the elastic connecting pin.

9. A functional testing method for a circuit board according to claim 8, characterized in that, It also includes a step of real-time verification of electrical connection status during functional testing: During the intervals in which the external testing equipment applies the test excitation signal, an electrical connection status verification cycle is inserted. During the electrical connection status verification period, verification signals are sent to some or all of the established temporary electrical connection paths through the external testing equipment or independent monitoring circuit. Analyze the response waveform or response data of the verification signal to determine whether there are open circuits, short circuits or impedance abnormalities in each path; Record the spring connector number, signal network name, and abnormality type corresponding to the abnormal path in the test log; Based on the verification results, a decision is made on whether to continue the subsequent testing process or to trigger an alarm to prompt the operator to check the contact status between the interface connection device and the circuit board under test.

10. A fixture for functional testing of a circuit board, applied to a functional testing method for a circuit board as described in any one of claims 1 to 9, characterized in that, The clamp includes: A support platform for placing a circuit board under test, the circuit board under test having a target interface area including signal pads and solder joints; A visual positioning system is used to acquire images and locate coordinates of the target interface area on the circuit board under test. Programmable 3D motion platform; At least one interface connection device is driven to move by the programmable three-dimensional motion platform, the interface connection device having a mounting surface facing the circuit board under test; Multiple flexible connecting pins are disposed on the mounting surface, each of the flexible connecting pins having a conductive contact at its end, and each of the flexible connecting pins being electrically connected to an external testing device via an independent connecting cable; And clamping components, including clips for clamping electrical components on the circuit board under test; The programmable three-dimensional motion platform is configured to drive the interface connection device to move and align with the target interface area based on the coordinate information obtained by the vision positioning system, and press the interface connection device against the circuit board under test, so that the conductive contacts of the plurality of elastic connection pins form elastic contact with the corresponding signal pads and solder joints in the target interface area to establish a temporary electrical connection path.

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