A circuit safety insulation test method for an intelligent power module

Abstract

The present application relates to the technical field of circuit test, and especially relates to a circuit safety insulation test method of an intelligent power module. The method comprises the following steps: establishing an electrical connection relationship between a golden finger in a test seat and the intelligent power module, setting a test connection environment, and obtaining a test seat connection network; connecting a voltage detection end in the test seat connection network to a predetermined voltage, detecting a pin contact condition of each intelligent power module, and setting a voltage signal disconnection time according to the pin contact condition; when the voltage signal disconnection time arrives, controlling a relay to disconnect the predetermined voltage, and simultaneously disconnecting a relay control connection between all current injection ends in the test seat and a single-chip microcomputer; switching the voltage detection end to a high-voltage output end of an insulation withstand voltage tester, and performing insulation performance detection; sorting defective products according to an insulation performance detection result, and displaying the current insulation performance detection result and the sorting defective product result. The present application helps to improve the safety and accuracy of insulation test.

Description

Technical Field

[0001] This invention relates to the field of circuit testing technology, and in particular to a method for testing the circuit safety insulation of a smart power module. Background Technology

[0002] As a core component of power electronic systems, the packaging reliability of IPMs (Intelligent Power Modules) directly affects the lifespan and safety of equipment. Current industry standards require IPM modules to pass insulation withstand voltage tests before leaving the factory to verify the absence of defects in the molding process. However, during the testing process, slight deformation after lead trimming may cause some leads to poor contact with the test fixture. Leads that are not shorted are easily damaged by high voltage during high-voltage testing, resulting in batch defects in good products.

[0003] Currently, before insulation withstand voltage testing, it is not checked whether the module pins are in good contact with the test fixture finger. High voltage is directly applied between the pins of the IPM module and the heat sink on the back. However, for multi-row, multi-pin devices like IPM modules, if a pin is deformed and not in contact with the test finger, high voltage may be applied to the chip. Generally, the insulation withstand voltage test voltage is greater than 1500V, while the chip withstand voltage is generally only 600V or 1200V. Without good contact, it is very easy to cause chip breakdown and cause batch accidents. Summary of the Invention

[0004] Therefore, it is necessary for the present invention to provide a circuit safety insulation test method for intelligent power modules to solve at least one of the above-mentioned technical problems.

[0005] To achieve the above objectives, a circuit safety insulation testing method for an intelligent power module is provided, applied to a test socket. The test socket includes a display screen, a sorting machine, a current injection terminal, a controller, a microcontroller, an insulation withstand voltage tester, a relay electrically connected to the controller, and gold fingers for an integrated voltage detection terminal. The sorting machine, display screen, gold fingers, current injection terminal, microcontroller, and insulation withstand voltage tester are all electrically connected to the controller. The method includes the following steps:

[0006] Step S1: Establish an electrical connection between the gold fingers inside the test socket and the intelligent power module, and set the test connection environment for the test socket to establish the electrical connection, thereby obtaining the test socket connection network;

[0007] Step S2: Connect the test socket to the voltage detection terminal in the network and apply a predetermined voltage to detect the pin contact of each smart power module, and set the voltage signal disconnection time according to the pin contact.

[0008] Step S3: When the voltage signal disconnection time is reached, control the relay to disconnect the predetermined voltage, and at the same time disconnect the relay control connection between all current injection terminals in the test socket and the microcontroller; switch the voltage detection terminal to the high voltage output terminal of the insulation withstand voltage tester, start the high voltage loading path, and perform insulation performance testing;

[0009] Step S4: Based on the insulation performance test results, sort out the defective products and display the current insulation performance test results and the sorting results of the defective products on the display screen.

[0010] This application uses a 5V voltage to detect the contact status of module pins, assessing their connection quality in real time and preventing high voltage from being directly applied to poorly contacted pins, which could cause chip breakdown. Subsequently, an adjustable voltage signal disconnection period is set before high voltage application, and the disconnection time is dynamically adjusted based on the voltage output status. An intermittent low duty cycle loading strategy is introduced to achieve transient voltage unloading and protection of the pins. Finally, the process switches to insulation withstand voltage testing, and the preliminary test results are corrected based on environmental parameters and material information. Through linkage with a sorting machine, the physical sorting of qualified and defective products is automatically completed. This effectively solves the problem of batch damage to good products due to poor pin contact in existing technologies, significantly improving the safety, accuracy, and automation level of insulation testing. Attached Figure Description

[0011] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0012] Figure 1 This is a schematic flowchart illustrating the circuit safety insulation test method for the intelligent power module of the present invention.

[0013] Figure 2 This is a schematic diagram of the circuit structure of the test socket in an embodiment of the present invention;

[0014] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0015] The technical method of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0016] Furthermore, the accompanying drawings are merely illustrative of the invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor methods and / or microcontroller methods.

[0017] It should be understood that although the terms "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are used merely to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0018] To achieve the above objectives, please refer to Figures 1 to 2 This invention provides a circuit safety insulation test method for intelligent power modules, the method comprising the following steps:

[0019] Step S1: Establish an electrical connection between the gold fingers inside the test socket and the intelligent power module, and set the test connection environment for the test socket to establish the electrical connection, thereby obtaining the test socket connection network;

[0020] In this embodiment, a test socket with a gold finger structure is installed on the test bench. The gold fingers adopt an upper and lower double spring clamping structure, and are press-fitted to form stable physical contact with each pin of the intelligent power module. Each pin is connected by a pair of metal contacts forming a Kelvin connection, which is used to realize independent paths for voltage detection and current injection. Inside the test socket, all voltage detection paths (Sense terminals) are converged to a unified node, and selectively connected to a 5V low-voltage source or the high-voltage positive terminal of an insulation withstand voltage tester through relays, forming a switchable test input network. At the same time, all current injection paths (Force terminals) are connected to relays one by one, and then connected to the microcontroller of the control unit to form a current control network. Finally, the above voltage detection network and current injection control network are integrated to construct the test socket connection network. The main control microcontroller initializes and collects the relay on / off status, input path configuration status, and electrical parameter status of each node to ensure that the test environment is configured correctly.

[0021] Step S2: Connect the test socket to the voltage detection terminal in the network and apply a predetermined voltage to detect the pin contact of each smart power module, and set the voltage signal disconnection time according to the pin contact.

[0022] In this embodiment, the main control microcontroller controls the relay to conduct, connecting the voltage detection terminal to a 5V voltage source, and sequentially applying a 5V DC voltage to the current injection terminal. The electrical response of each pin is judged by the data returned from the voltage detection terminal. Within 10ms after each injection channel is loaded, three sets of voltage data are sampled. If the stable level of the sampled data is between 4.9V and 5.1V, the voltage settling time does not exceed 20ms, and the voltage fluctuation range is less than ±0.1V, the pin is considered to have good contact. If any indicator fails to meet the preset threshold, it is marked as poor contact, and the 5V voltage source connection is immediately disconnected to prevent further testing. After this stage of detection is completed, the main control sets the transition period from the current time to before the planned high-voltage loading as the voltage signal disconnection time period, and sets the initial disconnection time to the current time plus 500ms. During this period, the voltage output status of the Sense terminal is collected in real time. If the output level fluctuation exceeds 0.1V within three consecutive cycles, the disconnection time is delayed by 50–100ms with the average fluctuation amplitude as the weight; if the output remains stable, the original disconnection time remains unchanged. The disconnection time is determined based on real-time feedback, and 50ms before disconnection, the relay is controlled to reduce the voltage injection duty cycle to below 50% in an intermittent loading manner to buffer electrical pressure.

[0023] Step S3: When the voltage signal disconnection time is reached, control the relay to disconnect the predetermined voltage, and at the same time disconnect the relay control connection between all current injection terminals in the test socket and the microcontroller; switch the voltage detection terminal to the high voltage output terminal of the insulation withstand voltage tester, start the high voltage loading path, and perform insulation performance testing;

[0024] In this embodiment, when the voltage signal disconnection time arrives, the main control microcontroller immediately controls the relay to disconnect the 5V voltage source, and simultaneously completely disconnects all current injection terminals from the microcontroller to avoid the risk of high-voltage backflow. Subsequently, the relay is switched to connect all voltage detection terminals to the high-voltage output positive terminal of the insulation withstand voltage tester, establishing a high-voltage loading path. At this time, the insulation withstand voltage tester begins executing a preset program, applying a 1500V DC voltage to each pin for 500ms, while simultaneously collecting leakage current values ​​and comparing them with a set tolerance threshold (e.g., 100μA). If the leakage current value of any pin exceeds the threshold, the module is marked as having poor insulation. During this stage, all channel leakage current data returned by the tester is stored and parsed by the main control microcontroller, and the results are marked as preliminary insulation test conclusions. Simultaneously, based on the test environment parameters collected by the on-site temperature and humidity sensors, combined with the material characteristics of the intelligent power module (e.g., epoxy resin encapsulation withstand voltage rating), the system automatically determines whether there are environmentally induced misjudgments. If it is confirmed that the abnormality is caused by environmental fluctuations, the relevant results are corrected.

[0025] Step S4: Sort out defective products according to the insulation performance test results, and display the current insulation performance test results and the results of sorting out defective products on the display screen.

[0026] In another embodiment, if the insulation performance test results have been transmitted back and the qualified / defective status has been marked, the product screening and result release stage is entered. In this embodiment, the main control single-chip microcomputer generates a sorting control instruction according to the test status of each module. The instruction content includes the module number, the test result, and the recommended physical sorting position number. This instruction is sent to the automatic sorter supporting the test platform. After receiving the instruction, the sorter controls the robotic arm to move the module to be tested from the test station to the corresponding collection area (such as the qualified product area A and the defective product area B). Synchronously, the display screen updates the current test status in real time, including the number of modules whose tests have been completed, the insulation test data chart of the current module, the final sorting position, and the sorting statistics summary, facilitating the operator to check and record. In addition, to meet the production traceability requirements, the system also exports all the test and sorting information as a CSV format file and stores it on the test main control platform, forming a complete data archiving chain.

[0027] Figure 2 It is a schematic circuit structure diagram of the test socket in the embodiment of the present invention; as Figure 2 shown, this test structure is built around the intelligent power module (DIP25), presenting an integrated circuit architecture of low-voltage detection - high-voltage loading - sorting control.

[0028] In the figure, in the center is the pin arrangement structure of the intelligent power module. The left and right sides are connected to the single-chip microcomputer through relays to achieve the on-off control of each current injection end. The green connection part is the voltage signal detection path, which is connected to the voltage detection end and the insulation withstand voltage tester; the red path is the high-voltage loading channel, which is used to switch through the relay in the early stage of the test to achieve the path conversion of the 5V low-voltage signal and the HV high-voltage signal.

[0029] In the figure, 5V and HV+ respectively correspond to the outputs of the low-voltage power supply and the insulation withstand voltage tester. The relay is used as a switching component to control different power supply loading paths; the single-chip microcomputer is connected to the display screen and the sorter module at the same time, facilitating the real-time monitoring of the test status and the control of product sorting. During pin testing, the contact situation is judged through the voltage detection feedback signal to ensure that the contact screening is completed before high-voltage loading and avoid the risk of breakdown.

[0030] In addition, the relay layout in the figure is of a symmetrical structure. The left side is the input control end, and the right side is the output drive and feedback end, realizing independent detection and control at the pin level. The overall structure is clear and the logic is reasonable, fully ensuring the safety and controllability of the test.

[0031] Optionally, the set test connection environment in step S1 includes:

[0032] By summarizing all the voltage detection terminals of the gold fingers of the test socket that have established electrical connections, a unified signal bus path is obtained. Then, by switching the connection between the 5V voltage source and the positive power terminal of the insulation withstand voltage tester through a relay, a voltage detection terminal connection network is obtained.

[0033] In this embodiment, if the test system completes the intelligent power module insertion operation and detects that the test socket's gold fingers have established initial physical contact with the module pins, the initialization configuration process of the test connection environment is initiated. All gold fingers inside the test socket are designed with a Kelvin dual-touch structure, leading out two sets of wires: the Sense terminal and the Force terminal. All Sense terminal lines are connected to a unified main bus via the inner layer of the PCB, forming a centralized voltage detection network. Based on this, a double-pole double-throw relay with a DPDT switching structure is configured to establish switching connections between the voltage detection main bus and two power sources: one end is a 5V low-voltage source used for the contact detection stage; the other end is the high-voltage positive terminal of the insulation withstand voltage tester used for subsequent insulation performance testing. The digital control logic of the relay achieves seamless switching between the two power sources, thereby constructing a complete and orderly voltage detection connection network.

[0034] Connect a relay to the current injection terminal of the test socket with the established electrical connection, and then connect the other end of the relay to a microcontroller to obtain the current injection terminal connection network.

[0035] In this embodiment, each Force terminal signal line (i.e., injection terminal) within the test socket is connected to an independent single-channel relay input terminal, while the relay output terminals are uniformly connected to the digital output pin of the control microcontroller. This structure achieves pin-by-pin discrete control of the Force injection voltage, meaning that during testing, the microcontroller can independently drive each relay channel, thereby sequentially applying a 5V voltage signal to each pin of the intelligent power module for bit-by-bit detection. Simultaneously, a voltage holding time setting capacitor and surge absorption components are introduced into the relay control circuit to ensure signal stability and interference-free operation during switching. This structure completes the construction of a current injection terminal connection network with timing control capabilities and fault channel isolation capabilities.

[0036] By integrating the voltage detection terminal connection network and the current injection terminal connection network, a test socket connection network is obtained.

[0037] In this embodiment, the main control microcontroller synchronously activates the control logic interfaces of both types of networks and reads all relay drive states, feedback signal states, and contact state sensor data within the system. After verifying that the integrity of each channel connection and the physical on / off relationship meet the test logic requirements, the system completes the synchronous integration of the two sub-networks, establishing a four-in-one test connection structure network including the input path (Force), monitoring path (Sense), control path (microcontroller I / O), and switching path (relay group). This network has features such as low-voltage contact judgment, high-voltage load switching, channel-specific control, and real-time status synchronization, laying the physical layer foundation for subsequent voltage load control and insulation judgment processes.

[0038] Optionally, switching the connection between the 5V voltage source and the positive power terminal of the insulation withstand voltage tester includes:

[0039] When checking the pin contact of each smart power module, the control relay is turned on, connecting the voltage detection terminal to the network to connect to a 5V voltage source, forming a low-voltage signal path;

[0040] Once all pin contact conditions have been checked and confirmed to be normal, the voltage signal disconnection time is set, and the relay is controlled to disconnect the 5V voltage source at the voltage signal disconnection time. Instead, the voltage detection terminal is switched to the positive power terminal of the insulation withstand voltage tester to establish a high-voltage loading path.

[0041] In this embodiment, the main control microcontroller sequentially activates the relay channels of each current injection terminal, applying a 5V DC voltage to each Force terminal inside the test socket. During this stage, the voltage detection network switches from the central relay to a 5V voltage source output, forming a complete Kelvin low-voltage detection path. By monitoring the voltage feedback value at the Sense terminal, the voltage response fluctuation, settling time, and feedback voltage tolerance value of each pin are collected to determine whether the pin is making good contact with the gold fingers. If the feedback status of all pins meets the contact judgment conditions of fluctuation amplitude less than ±0.1V, voltage settling time less than 20ms, and feedback voltage between 4.9V and 5.1V, the intelligent power module is determined to have normal contact and enters the subsequent high-voltage preparation stage. At this time, the main control microcontroller records the current moment as the contact detection completion time point and sets the voltage signal disconnection time period according to preset logic, setting the voltage signal disconnection time at the end of this time period.

[0042] In another embodiment, 50ms before the voltage signal disconnection time, a pre-switching signal is issued, and the following operations are performed: 1) the relays between all current injection terminals and the microcontroller are pre-disconnected, cutting off the control path to ensure the relay channel is in a high-impedance state; 2) the relays are controlled to disconnect the connection between the voltage detection terminal and the 5V low-voltage source, completely disconnecting the low-voltage signal path. Subsequently, the control logic immediately switches the relays to the high-voltage loading state, connecting the voltage detection terminal to the network and connecting it to the positive output terminal of the insulation withstand voltage tester. After the high-voltage source switching is completed, the high-voltage loading preparation command is executed, and the withstand voltage tester outputs an insulation test voltage in the range of 1500V to 2500V, formally establishing the high-voltage loading path.

[0043] Optionally, the detection of pin contact status for each smart power module in step S2 includes:

[0044] Based on the feedback from the voltage detection terminal after sequentially applying a 5V voltage signal to each current injection terminal, the contact between all gold fingers and the pins of the intelligent power module within the test socket is determined to be either good or poor. The determination of the contact condition includes:

[0045] If the response voltage fluctuation in the voltage detection terminal feedback within a unit time does not exceed the fluctuation amplitude threshold ±0.1V, the voltage settling time does not exceed the settling time threshold of 20ms, and the voltage feedback value of each pin is within the tolerance threshold of 4.9V to 5.1V, then the pin contact of the intelligent power module is considered to be good.

[0046] If any one of the following parameters—voltage fluctuation amplitude, voltage settling time, or voltage feedback value—exceeds the corresponding threshold within a unit of time, it is determined that the intelligent power module pin has poor contact, and the relay is immediately controlled to disconnect the 5V voltage source.

[0047] In this embodiment, the microcontroller of the test platform sequentially triggers the current injection terminals (Force terminals) connected to the pins of each intelligent power module at a fixed timing sequence, causing them to load a 5V voltage signal within a specified time window. During the loading process, the feedback voltage signal from the corresponding voltage detection terminal (Sense terminal) is simultaneously acquired. During each loading process, the voltage acquisition frequency of the Sense terminal is set to 1kHz, and the continuous acquisition time for each pin is no less than 100ms. The corresponding feedback data is then buffered into the data acquisition module. The maximum voltage value, minimum voltage value, first response delay time, and average stable voltage value of each pin within this time period are acquired.

[0048] In another embodiment, the control system performs contact status judgment based on the following judgment logic: 1) If the difference between the maximum voltage value and the minimum voltage value in the current pin acquisition data is less than ±0.1V, the first response delay time is less than 20ms, and the stable voltage value is between 4.9V and 5.1V, then the pin is judged to have good contact; 2) If any item in the detection result exceeds the above judgment threshold, the system will record the corresponding number of the pin as contact abnormal and trigger a fault response signal at the same time.

[0049] It is worth noting that when at least one pin is determined to have poor contact, the central relay will immediately disconnect the 5V voltage source output connection to prevent the risk of localized burning or breakdown of the loose pin due to abnormal sensing circuit caused by continuous voltage application. Simultaneously, the module will be marked as unqualified and await re-inspection, preventing it from entering the insulation testing process. If all pins complete the test under the aforementioned threshold conditions, confirming good contact, the module can proceed to the high-voltage preparation process and enter the voltage disconnection timing stage. This ensures controllable physical connection quality before high-voltage loading, avoiding high-voltage breakdown of the chip's core structure due to loose pin connections, and improving the safety and accuracy of insulation testing.

[0050] Optionally, setting the voltage signal disconnection time in step S2 includes:

[0051] The time period from the completion of the current detection pin contact status to the time before the high voltage loading is executed is set as the voltage signal disconnection time period, and the specific time when the voltage signal disconnection time period ends is determined as the initial voltage signal disconnection time.

[0052] During the voltage signal disconnection period, each current injection terminal is controlled to maintain a 5V voltage input, the voltage output status is sampled in real time, and the initial voltage signal disconnection time is adaptively adjusted according to the voltage output status to obtain the voltage signal disconnection time.

[0053] When the voltage signal disconnection time reaches 50ms before the voltage signal disconnection time, the connection between each current injection terminal of each test socket and the microcontroller is pre-disconnected by controlling each relay, and the input status of the static voltage detection terminal is also checked.

[0054] In this embodiment, if all pin contact detections of the intelligent power module are completed, the current time is immediately recorded as the pin contact detection completion time. Based on this time, combined with the high-voltage loading start time, a transition period (e.g., 100ms to 200ms) is pre-set. This transition period covers all preparatory actions from detection completion to high-voltage loading. Timing is started via the microcontroller's built-in timer, and the end of this transition period is marked as the initial voltage signal disconnection time. This disconnection time serves as a reference point for subsequent control circuit switching and relay disconnection, ensuring a safe transition from low-voltage detection to high-voltage testing.

[0055] In some embodiments, during a set voltage signal disconnection period (e.g., 100ms to 200ms), the 5V voltage input at each current injection terminal is continuously kept stable to ensure the intelligent power module is in a low-voltage excitation state. Simultaneously, the microcontroller synchronously acquires the voltage output status of each voltage detection terminal at a fixed sampling period (e.g., every 10ms), monitoring voltage fluctuation amplitude and level stability. If the difference between the maximum and minimum output voltage values ​​exceeds 0.1V within three consecutive sampling periods, the voltage state is determined to be abnormal. Based on the abnormal amplitude, the microcontroller dynamically adjusts the initial voltage signal disconnection time, delaying the disconnection time to ensure system voltage stability and prevent sudden voltage changes during switching due to excessive voltage fluctuations. Meanwhile, if the voltage fluctuation is stable during the sampling period, with the average level maintained within the range of 4.9V to 5.1V, the disconnection time remains unchanged. This adaptive adjustment mechanism effectively avoids false alarms and test anomalies caused by hardware state fluctuations.

[0056] In another embodiment, when the voltage signal disconnection timer reaches 50ms before the adjusted disconnection time, the microcontroller begins to gradually execute the relay pre-disconnection operation. Specifically, the relays connected to the microcontroller at each current injection terminal are controlled to enter the pre-disconnection state: under normal voltage output conditions, the relays operate according to a preset periodic on / off mode, for example, periodically opening and closing with a 100ms interval, reducing the voltage load intensity and preparing for high-voltage switching; if abnormal voltage fluctuations are detected, the relays use a pulse intermittent mode with a duty cycle of less than 50% to intermittently apply voltage, reducing the risk of impact. At the same time, the input state of the voltage detection terminal is kept still, that is, sampling and voltage changes are stopped, to prevent interference signals during the switching process from affecting the test data. This pre-disconnection operation effectively achieves a smooth transition of voltage input, providing a safety guarantee for the final disconnection of the relays and high-voltage loading.

[0057] Optionally, adaptive adjustment of the initial voltage signal disconnection time includes:

[0058] The voltage output state is considered abnormal if the difference between the maximum and minimum values ​​of the output level in three consecutive sampling periods exceeds 0.1V. The initial voltage signal disconnection time is adjusted accordingly based on the average over-limit amplitude of the difference to obtain the voltage signal disconnection time.

[0059] The voltage output status is considered normal if the average voltage is maintained between 4.9V and 5.1V during the continuous sampling period, and the initial voltage signal disconnection time is taken as the voltage signal disconnection time.

[0060] In this embodiment, if the voltage signal disconnection period begins after the pin contact detection is completed, the microcontroller continuously samples the output level of the voltage detection terminals corresponding to all intelligent power module pins with a sampling period of 10ms. After every 3 sampling periods, the deviation between the maximum and minimum voltage values ​​sampled within those 3 periods is calculated. .like If the voltage exceeds 0.1V, the output voltage state is judged as abnormal, and the sampled voltage is recorded. The difference between the value and the threshold of 0.1V is taken as the over-limit amplitude. Subsequently, the controller dynamically delays the initial voltage signal disconnection time by the over-limit amplitude multiplied by 10ms, for example... If the voltage is 0.15V, then the delay is (0.15V-0.1V)×10ms=0.5×10ms=5ms, thus postponing the voltage signal disconnection time by 5ms and resetting it to a new voltage signal disconnection time. This adaptive delay mechanism prevents premature voltage signal disconnection during periods of significant fluctuation, ensuring stable pin voltage before relay switching.

[0061] In another embodiment, if the microcontroller continuously samples for multiple cycles during the voltage signal disconnection period and averages the detected voltage of each cycle, and determines that the average voltage of three consecutive sampling cycles is stable between 4.9V and 5.1V, then the voltage output state is considered normal. In this case, the controller does not adjust the initial voltage signal disconnection time but directly uses that initial time as the final voltage signal disconnection time. During this process, each current injection terminal maintains a 5V voltage input to maintain a stable level, while the 5V signal is automatically cut off at the end of the disconnection period. This ensures that the pins are in a low-voltage state without significant fluctuations when the relay operates, preventing false jitter before subsequent high-voltage switching and achieving a smooth transition from low-voltage testing to high-voltage loading.

[0062] Optionally, the connection between each current injection terminal of the pre-disconnect test socket and the microcontroller includes:

[0063] If the voltage output status is determined to be normal, the relay is controlled to control the electrical connection between the current injection terminal and the microcontroller to be in a periodic on-off state with a preset intermittent on-off cycle until the voltage signal is disconnected.

[0064] If the voltage output status is determined to be abnormal, the relay is controlled to control the on / off state of the current injection terminal at a preset interval, and the voltage is intermittently applied to the pin of the intelligent power module with a duty cycle of less than 50% until the voltage signal is disconnected.

[0065] In some embodiments, if the average voltage output state is maintained within the range of 4.9V to 5.1V without abnormal fluctuations during the continuous sampling period, the microcontroller determines the voltage output state as normal and controls the relay to drive the electrical connection between the current injection terminal and the microcontroller according to a preset intermittent on / off cycle (e.g., 100ms on, 50ms off), thus putting it into a periodic on / off alternating operation mode. Specifically, during the on phase, the microcontroller is allowed to continuously provide a 5V voltage sustaining electrode excitation signal to the intelligent power module pin through the current injection terminal; during the off phase, the connection is temporarily disconnected to release residual parasitic capacitance voltage. This periodic on / off control is executed immediately after pin detection and continues until the timer reaches the finally determined voltage signal disconnection time, thereby achieving a safe control process from continuous low-voltage detection to complete low-voltage disconnection.

[0066] In another embodiment, if the output voltage fluctuation amplitude exceeds 0.1V for three consecutive sampling cycles during the voltage signal disconnection period, the microcontroller determines that the voltage output state is abnormal. To prevent the risk of surge due to unstable contacts at the pin before high voltage is applied, the relay control strategy at the current injection terminal is adjusted to an intermittent voltage loading mode with a duty cycle of less than 50% (e.g., 20ms high level, 40ms low level). In this control mode, the microcontroller briefly applies a 5V detection voltage to the pin during the high-level phase to maintain the identification of the pin's electrical path state; during the low-level phase, the loading is cut off, allowing the pin interface to fully dissipate transient voltage and parasitic current. The above intermittent loading continues to execute throughout the abnormal state until the voltage signal is disconnected, at which point all connections between the current injection terminals and the microcontroller are automatically disconnected, providing a hardware interface environment where voltage fluctuations are suppressed for the high-voltage loading step.

[0067] It is important to note that the high-level phase mentioned above refers to the situation where the relay is in the closed state, and a conductive loop is formed between the current injection terminal and the microcontroller, allowing the 5V DC voltage to be actually applied to the pins of the intelligent power module. At this time, the potential measured at the pins is close to the operating voltage of the external power supply side (approximately 4.9 to 5.1V), which is used to maintain the pin path excitation and detection state. The low-level phase refers to the situation where the relay is in the open state, and the connection between the current injection terminal and the microcontroller is cut off. The 5V voltage is no longer applied to the pins, and the module pins are in a state of near-floating or grounded state with the residual voltage gradually decaying. At this time, the potential drops rapidly to a level close to 0V or no higher than 0.3V, which is used to release the residual charge of parasitic capacitance and form a voltage input interval, thereby reducing the risk of instantaneous voltage surges before subsequent high-voltage loading.

[0068] Optionally, the insulation performance test in step S3 includes:

[0069] According to the set test parameters, control the insulation withstand voltage tester to apply a high voltage loading path to the pins of the intelligent power module and obtain the tester monitoring data;

[0070] The leakage current signal is detected based on the monitoring data of the tester, and compared with the leakage current signal according to the preset current tolerance range. If all pins of the smart power module are within the current tolerance range, the insulation performance of the smart power module is judged to be qualified; if any pin of the smart power module is not within the current tolerance range, the insulation performance of the smart power module is judged to be defective.

[0071] The smart power modules that were judged as qualified and defective products were integrated to obtain the initial insulation performance test results.

[0072] In this embodiment, the controller sends a start command to the insulation withstand voltage tester according to preset withstand voltage test parameters (test voltage AC1800V, holding time 3s, leakage current threshold 3mA), so that the high-voltage loading path at its output end is sequentially connected between each pin of the intelligent power module and the heat sink copper plate on the back, establishing a complete high-voltage path. During the test, the internal sampling module of the insulation withstand voltage tester monitors the leakage current change during the high-voltage loading process with a sampling period of 5ms. The sampling data includes timestamps, current peak values, and average values. The main control microcontroller receives the monitoring data in real time and performs synchronous comparison according to the unified time reference recorded at the start of the test. It compares the current signal monitored by each pin during the loading holding time with the preset current tolerance range one by one: if the leakage current of all pins is ≤3mA, a qualified judgment mark is output; if the leakage current of any pin is >3mA, its pin number and current peak value are recorded immediately, and a defective judgment mark is output. Finally, the judgment marks of all tested intelligent power modules are integrated to generate an initial insulation performance test result list, and qualified and defective products are sorted by module ID and transmitted to the subsequent sorting process.

[0073] Optionally, the method further includes:

[0074] Collect test environment parameters and identify environmental impact factors based on the acquired module design material data and test environment parameters;

[0075] Based on the environmental impact factor, identify the intelligent power modules that were judged as defective due to environmental impact in the initial insulation performance test results, and correct the initial insulation performance test results based on the proportion of pins outside the current tolerance range to obtain the insulation performance test results.

[0076] In this embodiment, sensors deployed in the testing environment read real-time environmental parameters such as indoor temperature (T), humidity (H), and air ionization (I) in the testing room. Embedded temperature and humidity sensors and an air ion concentration detection probe synchronously collect data at 2-second intervals. Simultaneously, design material data such as the dielectric constant of the encapsulation resin material, the surface roughness of the pin metal material, and the pad spacing of the intelligent power modules in the test batch are retrieved, achieving integrated input of multi-source parameters. The control processing core constructs environmental impact factor discrimination conditions based on a combination of factors such as the dielectric constant of the encapsulation resin material, the surface roughness of the pin metal material, and the pad spacing. For example, if the temperature and humidity exceed the threshold range (T>35℃ or H>80%) and the distance from the pad spacing d<0.7mm, it is judged as a high-risk environment mode; if the environment remains within the process-recommended range (T≤35℃ and H≤80%), it is judged as a standard environment mode. Finally, an environmental impact factor label corresponding to each test batch is output for subsequent correction of the original insulation test results.

[0077] In another embodiment, if the environmental impact factor is identified as a high-risk environmental mode, the control processing core locates the smart power modules with defective labels in the initial insulation performance test results and counts the number of pins in each module that failed the tolerance judgment. With total number of pins Calculate its failure rate ;when When the value is between 0.05 and 0.15, the module identifies the product as potentially defective due to environmental factors, executes a correction process, and temporarily marks the initial defective product as retestable; if... If the value is greater than 0.15, the defective product judgment remains unchanged. When the environmental impact factor is in the standard environmental mode, all initial test results remain unchanged. Through the above judgment and correction logic, the final insulation performance test result is output by comprehensively considering environmental parameters, material characteristics, and the proportion of pins exceeding limits, thereby achieving accurate optimization of test conclusions and stable improvement of production line yield.

[0078] Optionally, step S5 includes:

[0079] Based on the insulation performance test results, a corresponding sorting control command is assigned to each intelligent power module, and the sorting control command is sent to the sorting machine;

[0080] After receiving the sorting control command, the sorting machine drives the execution component of the sorting machine to move the intelligent power module that has completed the detection to the corresponding physical position in order to automatically sort the intelligent power module;

[0081] The display screen shows the physical location of each smart power module and the results of its insulation performance test.

[0082] In this embodiment, if the insulation performance test results have been calibrated and the corresponding test judgment flag for each intelligent power module has been determined, the microcontroller sequentially traverses the test results according to the module identification number (e.g., ID001–ID200), marking modules judged as qualified as category A, modules judged as defective as category B, and modules judged as retestable as retestable C, thus constructing a sorting control instruction table including module ID, instruction type, and corresponding target physical location index (e.g., qualified area: X1, NG area: X2). Subsequently, the sorting control instructions are packaged and transmitted to the sorting machine controller in real time via the RS485 bus protocol, thereby maintaining synchronization between the test system and the downstream sorting mechanism and reducing buffering time.

[0083] In another embodiment, if the sorting machine controller receives a sorting control instruction table from the microcontroller, it immediately schedules the internal execution components, including the push rod driver and the slide rail gripping device that move along the conveyor belt, to locate the intelligent power modules that have completed the test one by one according to the module ID order in the instruction table. When the classification A instruction is identified, the push rod is driven to slide the corresponding module into the qualified receiving trough; when the classification B instruction is identified, the module is pushed into the defective product collection trough until the batch sorting is completed; when the retestable C instruction is identified, the intelligent power module is not directly sorted into the qualified or defective product area, but a retest return operation is performed. During the sorting process, the upper computer monitoring software records the module position data and dynamically displays the sorting physical position of each module (e.g., ID007 → qualified area X1, ID035 → NG area X2) and the corresponding insulation test result mark on the display screen, so that the operator can intuitively confirm the correctness of the sorting action and record the sorting traceability information.

[0084] It is worth noting that the retesting reflow operation specifically includes: transferring modules determined to be retestable to the retesting buffer (e.g., intermediate buffer slot or retesting channel entrance) via a pre-deployed gripping device, instead of the qualified or NG area; the sorting machine simultaneously sends a retesting status signal to the host computer, recording the module's ID and location information; the host computer control logic will trigger a re-entry into the low-pressure detection + high-pressure test process after a certain number of modules have accumulated in the retesting buffer (or the current batch ends), to perform a complete retest on these C-command modules. The pre-deployed gripping device can be a variety of automated gripping components, such as a vacuum suction robotic arm or a clamping robotic gripper, and can be selected and deployed according to the production line tooling and the packaging structure of the module under test; this invention does not impose any limitations on this.

[0085] Therefore, the embodiments should be considered as exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the application are intended to be included within the invention.

[0086] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A method for testing the circuit safety insulation of an intelligent power module, characterized in that, The method is applied to a test socket, which includes a display screen, a sorting machine, a current injection terminal, a controller, a microcontroller, an insulation withstand voltage tester, a relay electrically connected to the controller, and gold fingers for integrated voltage detection terminals. The sorting machine, display screen, gold fingers, current injection terminal, microcontroller, and insulation withstand voltage tester are all electrically connected to the controller. The method includes the following steps: Step S1: Establish an electrical connection between the gold fingers inside the test socket and the intelligent power module, and set the test connection environment for the test socket to establish the electrical connection, thereby obtaining the test socket connection network; Step S2: Connect the test socket to the voltage detection terminal in the network and apply a predetermined voltage to detect the pin contact of each smart power module, and set the voltage signal disconnection time according to the pin contact. Step S3: When the voltage signal disconnection time is reached, control the relay to disconnect the predetermined voltage, and at the same time disconnect the relay control connection between all current injection terminals in the test socket and the microcontroller; switch the voltage detection terminal to the high voltage output terminal of the insulation withstand voltage tester, start the high voltage loading path, and perform insulation performance testing; Step S4: Based on the insulation performance test results, sort out the defective products and display the current insulation performance test results and the sorting results of the defective products on the display screen.

2. The circuit safety insulation test method for intelligent power modules according to claim 1, characterized in that, Step S1 involves setting up the test connection environment, including: By summarizing all the voltage detection terminals of the gold fingers of the test socket that have established electrical connections, a unified signal bus path is obtained. Then, by switching the connection between the 5V voltage source and the positive power terminal of the insulation withstand voltage tester through a relay, a voltage detection terminal connection network is obtained. Connect a relay to the current injection terminal of the test socket with the established electrical connection, and then connect the other end of the relay to a microcontroller to obtain the current injection terminal connection network. By integrating the voltage detection terminal connection network and the current injection terminal connection network, a test socket connection network is obtained.

3. The circuit safety insulation test method for intelligent power modules according to claim 2, characterized in that, Switching between the 5V voltage source and the positive power terminal of the insulation withstand voltage tester includes: When checking the pin contact of each smart power module, the control relay is turned on, connecting the voltage detection terminal to the network to connect to a 5V voltage source, forming a low-voltage signal path; Once all pin contact conditions have been checked and confirmed to be normal, the voltage signal disconnection time is set, and the relay is controlled to disconnect the 5V voltage source at the voltage signal disconnection time. Instead, the voltage detection terminal is switched to the positive power terminal of the insulation withstand voltage tester to establish a high-voltage loading path.

4. The circuit safety insulation test method for intelligent power modules according to claim 1, characterized in that, Step S2, which involves detecting the pin contact status of each smart power module, includes: Based on the feedback from the voltage detection terminal after sequentially applying a 5V voltage signal to each current injection terminal, the contact between all gold fingers and the pins of the intelligent power module within the test socket is determined to be either good or poor. The determination of the contact condition includes: If the response voltage fluctuation in the voltage detection terminal feedback within a unit time does not exceed the fluctuation amplitude threshold ±0.1V, the voltage settling time does not exceed the settling time threshold of 20ms, and the voltage feedback value of each pin is within the tolerance threshold of 4.9V to 5.1V, then the pin contact of the intelligent power module is considered to be good. If any one of the following parameters—voltage fluctuation amplitude, voltage settling time, or voltage feedback value—exceeds the corresponding threshold within a unit of time, it is determined that the intelligent power module pin has poor contact, and the relay is immediately controlled to disconnect the 5V voltage source.

5. The circuit safety insulation test method for intelligent power modules according to claim 1, characterized in that, The step S2 includes setting the voltage signal disconnection time, which includes: The time period from the completion of the current detection pin contact status to the time before the high voltage loading is executed is set as the voltage signal disconnection time period, and the specific time when the voltage signal disconnection time period ends is determined as the initial voltage signal disconnection time. During the voltage signal disconnection period, each current injection terminal is controlled to maintain a 5V voltage input, the voltage output status is sampled in real time, and the initial voltage signal disconnection time is adaptively adjusted according to the voltage output status to obtain the voltage signal disconnection time. When the voltage signal disconnection time reaches 50ms before the voltage signal disconnection time, the connection between each current injection terminal of each test socket and the microcontroller is pre-disconnected by controlling each relay, and the input status of the static voltage detection terminal is also checked.

6. The circuit safety insulation test method for intelligent power modules according to claim 5, characterized in that, The adaptive adjustment of the initial voltage signal disconnection time includes: The voltage output state is considered abnormal if the difference between the maximum and minimum values ​​of the output level in three consecutive sampling periods exceeds 0.1V. The initial voltage signal disconnection time is adjusted accordingly based on the average over-limit amplitude of the difference to obtain the voltage signal disconnection time. The voltage output status is considered normal if the average voltage is maintained between 4.9V and 5.1V during the continuous sampling period, and the initial voltage signal disconnection time is taken as the voltage signal disconnection time.

7. The circuit safety insulation test method for intelligent power modules according to claim 5, characterized in that, The connections between the current injection terminals of the pre-disconnect test socket and the microcontroller include: If the voltage output status is determined to be normal, the relay is controlled to control the electrical connection between the current injection terminal and the microcontroller to be in a periodic on-off state with a preset intermittent on-off cycle until the voltage signal is disconnected. If the voltage output status is determined to be abnormal, the relay is controlled to control the on / off state of the current injection terminal at a preset interval, and the voltage is intermittently applied to the pin of the intelligent power module with a duty cycle of less than 50% until the voltage signal is disconnected.

8. The circuit safety insulation test method for intelligent power modules according to claim 1, characterized in that, The insulation performance test in step S3 includes: According to the set test parameters, control the insulation withstand voltage tester to apply a high voltage loading path to the pins of the intelligent power module and obtain the tester monitoring data; The leakage current signal is detected based on the monitoring data of the tester, and compared with the leakage current signal according to the preset current tolerance range. If all pins of the smart power module are within the current tolerance range, the insulation performance of the smart power module is judged to be qualified; if any pin of the smart power module is not within the current tolerance range, the insulation performance of the smart power module is judged to be defective. The smart power modules that were judged as qualified and defective products were integrated to obtain the initial insulation performance test results.

9. The circuit safety insulation test method for intelligent power modules according to claim 1, characterized in that, The method further includes: Collect test environment parameters and identify environmental impact factors based on the acquired module design material data and test environment parameters; Based on the environmental impact factor, identify the intelligent power modules that were judged as defective due to environmental impact in the initial insulation performance test results, and correct the initial insulation performance test results based on the proportion of pins outside the current tolerance range to obtain the insulation performance test results.

10. The circuit safety insulation test method for the intelligent power module according to claim 1, characterized in that, Step S5 includes: Based on the insulation performance test results, a corresponding sorting control command is assigned to each intelligent power module, and the sorting control command is sent to the sorting machine; After receiving the sorting control command, the sorting machine drives the execution component of the sorting machine to move the intelligent power module that has completed the detection to the corresponding physical position in order to automatically sort the intelligent power module; The display screen shows the physical location of each smart power module and the results of its insulation performance test.

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