Crimping IGBT device metal layer monitoring equipment, clamp system and monitoring method

Abstract

The invention relates to the technical field of semiconductor monitoring equipment, in particular to crimping IGBT (Insulated Gate Bipolar Translator) device metal layer monitoring equipment, comprising a main current unit which comprises a conductive copper column electrically connected with a to-be-tested crimping part; the signal sampling unit comprises a plurality of signal thimbles connected with the to-be-tested crimping part, and a PCB (Printed Circuit Board) connected with the signal thimbles; wherein the signal sampling unit and the main current unit are in concurrent contact on a metal layer on the upper end face of the to-be-tested crimping part, and a current path and a sampling path are mutually independent. The four-point method monitoring device is integrated on the power cycle test platform, so that the change of the resistance of the metal layer can be monitored in real time and on line in the actual working (power cycle) process of the crimping part to be tested, the aging state of the metal layer is directly reflected, the defect that the dynamic aging process cannot be captured in the traditional off-line detection is overcome, and the test efficiency is improved. And dynamic data support is provided for reliability evaluation and residual life prediction of the to-be-tested crimping part.

Description

Technical Field

[0001] This invention relates to the field of semiconductor monitoring equipment technology, and in particular to a monitoring device, fixture system and monitoring method for the metal layer of a press-fit IGBT device. Background Technology

[0002] Press-fit IGBTs are core switching devices in high-power equipment such as flexible DC transmission and rail transit, and their reliability directly determines system safety. The metal layer on the chip surface serves both as a current redistribution function and a direct conductive channel at the press-fit interface. Under long-term power cycling or temperature shocks, the metal layer is prone to electromigration, cracking, oxidation, or interfacial fretting wear, leading to a slow increase in contact resistance and ultimately device failure. Therefore, online and in-situ monitoring of the aging state of the metal layer is a crucial step in assessing the remaining lifespan of press-fit IGBTs and enabling predictive maintenance.

[0003] Currently, reliability assessments of press-fit IGBT devices largely rely on offline testing or accelerated aging experiments, lacking effective means for online, in-situ monitoring of the metal layer's aging status during power cycling. Existing technologies lack dedicated fixtures or monitoring systems capable of acquiring real-time, accurate information on metal layer resistance changes under actual operating conditions. This makes it impossible to promptly determine the metal layer's health status and hinders predictive maintenance for the device's remaining lifespan. Summary of the Invention

[0004] In this section, as well as in the abstract and title of this application, some simplifications or omissions may be made to avoid obscuring the purpose of this section, the abstract, and the title of this application, and such simplifications or omissions shall not be used to limit the scope of the invention.

[0005] To address the shortcomings of existing technologies, one objective of this invention is to provide a monitoring device for the metal layer of a press-fit IGBT device.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a metal layer monitoring device for a press-fit IGBT device, comprising a main current unit, which includes conductive copper pillars electrically connected to the press-fit device under test; a signal sampling unit, which includes a plurality of signal pins connected to the press-fit device under test, and a PCB board connected to the signal pins; wherein the signal sampling unit and the main current unit are in point contact with the metal layer on the upper surface of the press-fit device under test, and the current path and the sampling path are independent of each other.

[0007] In a preferred embodiment of the metal layer monitoring device for the crimped IGBT device described in this invention, the conductive copper pillar includes a female sleeve, a male sleeve, and a pressure spring; the female sleeve is in contact with the metal layer of the crimped component to be tested; the male sleeve is movably connected to the female sleeve; the pressure spring is connected between the female sleeve and the male sleeve; and a through hole penetrating the conductive copper pillar is provided on the PCB board.

[0008] As a preferred embodiment of the metal layer monitoring device for the press-fit IGBT device described in this invention, the signal pins are divided into a current pin group and a voltage pin group, and each group has at least two pins; wherein the current pin group is in contact with the metal layer, and the voltage pin group is in contact with the metal layer and is electrically connected to the main current unit.

[0009] As a preferred embodiment of the metal layer monitoring device for the IGBT device described in this invention, the signal sampling unit further includes insulating bakelite, the upper end face of which abuts against the PCB board, and the lower end face is stacked on the surface of the IGBT to be tested. The insulating bakelite is provided with a first limiting hole that penetrates the signal pin and a second limiting hole that penetrates the conductive copper pillar. The insulating bakelite is provided in several groups on the surface of the IGBT to be tested, and each group of insulating bakelite is provided with at least one conductive copper pillar.

[0010] As a preferred embodiment of the metal layer monitoring device for the press-fit IGBT device of the present invention, the main current unit further includes a conductive copper block connected to a plurality of conductive copper pillars in insulating bakelite; the conductive copper block is provided with a connecting groove that mates with the conductive copper pillars, and the male sleeve is connected to the top of the inner surface of the connecting groove; wherein, the lower end face of the conductive copper block has an axial displacement distance H1 with the PCB board, and the male sleeve and the female sleeve have an elastic gap H2, wherein H2 > H1.

[0011] As a preferred embodiment of the metal layer monitoring device for the crimped IGBT device of the present invention, the signal pin includes a fixed end, a contact end, and a buffer spring; the fixed end passes through the first limiting hole and is fixedly connected to the lower end face of the PCB board; the contact end is movably connected to the fixed end and makes contact with the metal layer of the crimped component to be tested; the buffer spring is connected between the fixed end and the contact end.

[0012] As a preferred embodiment of the metal layer monitoring device for the crimped IGBT device described in this invention, the crimped component to be tested is provided with a protective shell, and the protective shell is provided with a limiting port that penetrates the insulating bakelite.

[0013] The beneficial effects of the metal layer monitoring device for crimped IGBT devices of the present invention are as follows: By integrating a four-point monitoring device on a power cycling test platform, the present invention can monitor the change of metal layer resistance in real time and online during the actual operation (power cycling) of the crimped device under test, directly reflecting the aging state of the metal layer. This overcomes the shortcomings of traditional offline testing that cannot capture the dynamic aging process, and provides dynamic data support for the reliability assessment and remaining life prediction of the crimped device under test.

[0014] To address the shortcomings of the prior art, another objective of this invention is to provide a clamping system.

[0015] To achieve the above objectives, the present invention adopts the following technical solution: a clamping system, including a metal layer monitoring device for pressing IGBT devices, and a frame, the frame including a pressing end and a supporting end, at least two test platforms are arranged between the pressing end and the supporting end, a positive electrode plate is connected between the pressing end and the upper test platform, and a negative electrode plate is connected between the supporting end and the lower test platform; wherein, the lower end face of the upper test platform is connected to a conductive copper block, and the upper end face of the lower test platform is in contact with the lower end face of the pressing component to be tested.

[0016] In a preferred embodiment of the fixture system of the present invention, a first positioning hole is provided on the test platform, a second positioning hole is provided on the conductive copper block, and a positioning post is provided between the first positioning hole and the second positioning hole.

[0017] The advantages of the clamping system of the present invention are as follows: Through the cooperative structure of the first positioning hole, the second positioning hole, and the positioning post, the present invention enables precise axial stacking and positioning of multiple monitoring devices on the same clamping system frame. This allows the device to simultaneously perform power cycle aging tests and online monitoring on multiple pressure fittings under test, significantly improving testing efficiency. When the frame is subjected to overall tightening pressure, this positioning structure effectively prevents lateral displacement or torsion of the monitoring devices at each layer, ensuring the consistency of the pressure transmission path and the stability of electrical contact, thereby guaranteeing reliability and data accuracy during parallel testing.

[0018] As a preferred embodiment of the monitoring method described in this invention, the method includes the following steps: S1: Place the pressure fitting to be tested on the test platform below the fixture system, with the metal layer of the device facing upwards; stack the insulating bakelite, PCB board, and conductive copper block sequentially on top of the device, and make the current pin group, voltage pin group, and the lower end of the conductive copper pillar form a common point contact on the surface of the metal layer; S2: Drive the pressure end of the fixture system to move downwards, the positive plate pushes the conductive copper block, and the male sleeve of the conductive copper pillar compresses the pressure spring and generates an axial displacement distance H1 relative to the female sleeve, until the female sleeve establishes a stable main current path with the metal layer, while the voltage pin group remains unaffected under the action of the buffer spring. S3: Connect the current pin group of the main current unit to the external constant current source to form a Force loop, and connect the voltage pin group to the Kelvin interface of the PCB board to form a Sense loop; S4: Inject a constant DC or pulse current into the metal layer through the main current unit, and at the same time, collect the no-current voltage drop signal on the surface of the metal layer through the voltage pin group in a four-point method, and send the signal to the PCB board. The host computer electrically connected to the PCB board calculates the real-time resistance; S5: Repeat step S4 during the power cycle, record the relative change in resistance, and determine the aging failure of the metal layer when the resistance exceeds the set threshold, so as to realize online monitoring. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the conductive copper pillar, signal pin, and metal layer of the present invention.

[0021] Figure 2 This is a schematic diagram of the conductive copper pillar, PCB board, and pressure fitting to be tested according to the present invention.

[0022] Figure 3 This is a schematic diagram of the PCB board structure of the present invention.

[0023] Figure 4 This is a schematic diagram of the structure of the conductive copper pillar of the present invention.

[0024] Figure 5 This is a schematic diagram of the structure of the insulating bakelite of the present invention.

[0025] Figure 6 This is a schematic diagram showing the distribution of the current-type ejector pin group and the voltage-type ejector pin group of the present invention.

[0026] Figure 7 This is a schematic diagram of the connecting groove and conductive copper block of the present invention.

[0027] Figure 8 This is a schematic diagram of the conductive copper pillar of the present invention in a state where it is not in contact with the PCB board.

[0028] Figure 9 This is a schematic diagram showing the contact state between the conductive copper pillar of the present invention and the PCB board.

[0029] Figure 10 This is a schematic diagram of the signal pin structure of the present invention.

[0030] Figure 11 This is a schematic diagram of the main current unit and signal sampling unit of the present invention.

[0031] Figure 12 This is a three-dimensional schematic diagram of the overall structure of the present invention.

[0032] Figure 13 This is a schematic diagram of the test platform and conductive copper block of the present invention.

[0033] Figure 14 This is an exploded view of the test platform and conductive copper block of the present invention.

[0034] Figure 15 This is a flowchart of the detection method of the present invention. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0036] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0037] Reference Figures 1-2 This embodiment provides a metal layer monitoring device for a crimped IGBT device, including a main current unit 100, which includes conductive copper pillars 102 electrically connected to the crimped component 101 under test; and a signal sampling unit 200, which includes a plurality of signal pins 201 connected to the crimped component 101 under test, and a PCB board 202 connected to the signal pins 201; wherein the signal sampling unit 200 and the main current unit 100 are in point contact with the metal layer S on the upper surface of the crimped component under test, and the current path and the sampling path are independent of each other.

[0038] Among them, the main current unit 100 and the signal sampling unit 200 are two functionally distinct and relatively independent units. The core function of the main current unit 100 is to carry out the flow of large current and provide the necessary current excitation for measurement. The core function of the signal sampling unit 200 is to extract electrical signals (voltage) that reflect the health status of the metal layer S with high precision, while hardly diverting the main current.

[0039] Main current path: external constant current source → conductive copper block 103 → conductive copper pillar 102 → metal layer S → inside the device under test.

[0040] Voltage sampling path: Metal layer S → Signal pin 201 → PCB board 202 → Host computer.

[0041] The metal layer S is located on the upper surface of the pressure fitting 101 to be tested. The PCB board 202 is connected to the host computer. The voltage pin group 201b collects the no-current voltage drop signal on the surface of the metal layer S in a four-point method and sends the signal to the PCB board 202. The host computer, which is electrically connected to the PCB board 202, calculates the real-time resistance.

[0042] Reference Figures 3-4 This embodiment provides a metal layer monitoring device for crimped IGBT devices, including a conductive copper pillar 102 comprising a female sleeve 102a, a male sleeve 102b, and a pressure spring 102c; the female sleeve 102a is in contact with the metal layer S of the crimped component 101 to be tested; the male sleeve 102b is movably connected to the female sleeve 102a; the pressure spring 102c is connected between the female sleeve 102a and the male sleeve 102b; wherein, a through hole 102d penetrating the conductive copper pillar 102 is provided on the PCB board 202.

[0043] When pressure is applied by the clamping system, the pressure is transmitted to the male sleeve 102b through the conductive copper block 103. The male sleeve 102b then moves downward, compressing the pressure spring 102c, instead of rigidly transmitting the pressure to the female sleeve 102a and directly impacting the pressure-sensitive connector 101 under test. Under the action of the spring force, the female sleeve 102a contacts the metal layer S with a controllable and gentle force. This design decouples the huge mechanical clamping force from the sensitive chip surface, ensuring that while applying sufficient pressure to reduce contact resistance, it effectively avoids mechanical damage such as indentations and cracks to the fragile metal layer S caused by excessive pressure or non-parallel installation, thus achieving non-destructive testing.

[0044] The continuous elastic force provided by the pressure spring 102c ensures that the electrical contact between the female sleeve 102a and the metal layer S, as well as between the male sleeve 102b and the female sleeve 102a, remains stable and reliable throughout the entire life test cycle. Even when high and low temperature cycles cause the material to expand and contract, good contact can still be maintained.

[0045] To provide a passageway for the retractable conductive copper pillar 102, a through-hole 102d is pre-installed on the PCB board 202. The diameter of the through-hole 102d is slightly larger than the maximum outer diameter of the conductive copper pillar 102, ensuring that the conductive copper pillar 102 does not come into contact with or rub against the PCB board 202 when passing through it. This ensures electrical isolation between the main current path (flowing through the conductive copper pillar 102) and the signal measurement path (laid out on the PCB board 202), preventing signal crosstalk.

[0046] Reference Figures 5-6 This embodiment provides a metal layer monitoring device for a press-fit IGBT device, including several signal pins 201 divided into current pin group 201a and voltage pin group 201b, with at least two pins in each group; wherein, the current pin group 201a is in contact with the metal layer S, and the voltage pin group 201b is in contact with the metal layer S and is electrically connected to the main current unit 100.

[0047] The current pin group 201a (Force circuit) and the voltage pin group 201b (Sense circuit) are physically and electrically independent of each other. The strong current flowing through the Force circuit will not flow into the high-impedance Sense circuit.

[0048] This grouping design allows for the precise measurement of the minute resistance value R of the metal layer S. During power cycling aging, any minute cracks, oxidation, or electromigration in the metal layer S that cause an increase in resistance can be detected by this highly sensitive measurement method, thus enabling accurate, online monitoring of the aging state of the metal layer S.

[0049] Furthermore, the signal sampling unit 200 also includes an insulating bakelite 203. The upper end face of the insulating bakelite 203 abuts against the PCB board 202, and the lower end face is stacked on the surface of the pressure fitting 101 to be tested. The insulating bakelite 203 is provided with a first limiting hole 203a that penetrates the signal pin 201 and a second limiting hole 203b that penetrates the conductive copper pillar 102. The insulating bakelite 203 is provided in several groups on the surface of the pressure fitting 101 to be tested, and each group of insulating bakelite 203 is provided with at least one conductive copper pillar 102.

[0050] The first limiting hole 203a and the second limiting hole 203b are used to fix the signal pin 201 and the conductive copper pillar 102, respectively. The value and number of the first limiting hole 203a correspond to the number and position of the signal pin 201, and the value and number of the second limiting hole 203b correspond to the value and number of the conductive copper pillar 102.

[0051] The number of conductive copper pillars 102 on each set of insulating bakelite 203 can be adjusted according to the actual current measurement requirements. Similarly, the number of second limiting holes 203b on the insulating bakelite 203 used to fix the conductive copper pillars 102 can also be adjusted. The position of the conductive copper pillars 102 on each set of insulating bakelite 203 is not restricted and is set according to the metal layer S of the pressure connector 101 (chip) to be tested. It should be noted that the positions of the conductive copper pillars 102 and the four signal pins 201 on the insulating bakelite 203 need to be staggered (including the positions of the first limiting hole 203a and the second limiting hole 203b).

[0052] Reference Figure 4 , Figures 7-9 This embodiment provides a metal layer monitoring device for a press-fit IGBT device, including a main current unit 100 and a conductive copper block 103 connected to conductive copper pillars 102 in a plurality of insulating bakelite 203; the conductive copper block 103 is provided with a connecting groove 103a that mates with the conductive copper pillars 102, and the male sleeve 102b is connected to the top of the inner surface of the connecting groove 103a; wherein, there is an axial displacement distance H1 between the lower end face of the conductive copper block 103 and the PCB board 202, and there is an elastic gap H2 between the male sleeve 102b and the female sleeve 102a, where H2 > H1.

[0053] The male sleeve 102b is radially limited by the side wall of the connecting groove 103a to prevent it from deflecting under pressure, ensuring that the pressure is transmitted vertically along the axial direction and avoiding lateral force that could cause structural jamming or poor contact.

[0054] By setting the conductive copper block 103 and the connecting groove 103a, the current can be synchronously transmitted through the conductive copper block 103 to multiple conductive copper pillars 102 at different positions on the pressure connector 101 to be tested.

[0055] During the pressure application process of the clamping system, the conductive copper block 103 moves downward a maximum distance of H1. Since H2 > H1, this means that even under maximum pressure, after the male sleeve 102b moves downward a distance of H1, it will not impact the mechanical limiting surface inside the female sleeve 102a. Therefore, the enormous pressure applied to the conductive copper block 103 is completely absorbed by the compressed pressure spring 102c and converted into an elastic force that brings the female sleeve 102a into contact with the metal layer S.

[0056] If H2≤H1, under pressure, the male sleeve 102b will bottom out first, forming a rigid connection with the female sleeve 102a. This would cause external pressure to act directly and rigidly on the chip, losing the protective function of the telescopic buffer. The design of H2>H1 fundamentally prevents this from happening, ensuring that the contact force acting on the chip is always a gentle and controllable spring force, rather than a huge external mechanical clamping force.

[0057] Reference Figures 10-11 This embodiment provides a metal layer monitoring device for IGBT devices, including a signal pin 201, which includes a fixed end 201c, a contact end 201d, and a buffer spring 201e; the fixed end 201c passes through a first limiting hole 203a and is fixedly connected to the lower end face of the PCB board 202; the contact end 201d is movably connected to the fixed end 201c and is in contact with the metal layer S of the press-fit component 101 to be tested; the buffer spring 201e is connected between the fixed end 201c and the contact end 201d.

[0058] By setting a retractable signal pin 201, the signal pin 201 does not bear the main mechanical pressure, but only maintains a good electrical contact state, thereby improving the accuracy of voltage measurement.

[0059] Furthermore, the external part of the crimping component 101 to be tested is provided with a protective shell 204, and the protective shell 204 is provided with a limiting port 205 that penetrates the insulating bakelite 203.

[0060] The protective shell 204 includes the upper surface and surrounding area of ​​the crimping component 101 to be tested, and the limiting port 205 is used to limit and fix the insulating bakelite 203 to prevent the insulating bakelite 203 from shifting position.

[0061] Reference Figures 12-14 This embodiment provides a clamping system, including a metal layer monitoring device for pressing IGBT devices, and a frame 300. The frame 300 includes a pressing end 301 and a supporting end 302. At least two test platforms are provided between the pressing end 301 and the supporting end 302. A positive electrode plate 304 is connected between the pressing end 301 and the upper test platform, and a negative electrode plate 305 is connected between the supporting end 302 and the lower test platform. The lower end face of the upper test platform is connected to a conductive copper block 103, and the upper end face of the lower test platform is in contact with the lower end face of the pressing component 101 to be tested.

[0062] Furthermore, a first positioning hole 306 is provided on the test platform, a second positioning hole 307 is provided on the conductive copper block 103, and a positioning post 308 is provided between the first positioning hole 306 and the second positioning hole 307.

[0063] The mating structure of the first positioning hole 306, the second positioning hole 307, and the positioning post 308 enables precise axial stacking and positioning of multiple monitoring devices on the frame 300 of the same fixture system. This allows the device to simultaneously perform power cycle aging tests and online monitoring on multiple pressure fittings 101 under test, significantly improving testing efficiency. When the frame 300 is tightened and pressurized as a whole, this positioning structure effectively prevents lateral displacement or torsion of the monitoring devices at each layer, ensuring the consistency of the pressure transmission path and the stability of electrical contact, thereby guaranteeing reliability and data accuracy during parallel testing.

[0064] Reference Figure 15 This embodiment provides a monitoring method, including the following steps: S1: Place the pressure connector 101 to be tested on the test platform below the fixture system, with the metal layer S of the device facing upwards; stack the insulating bakelite 203, PCB board 202, and conductive copper block 103 on top of the device in sequence, and make the current pin group 201a, voltage pin group 201b, and the lower end of the conductive copper pillar 102 form a common point contact on the surface of the metal layer S; S2: Drive the pressure end 301 of the fixture system to move downwards, and the positive electrode plate 304 pushes the conductive copper block 103 and the conductive copper pillar. S1: The male sleeve 102b of 102 compresses the pressure spring 102c and generates an axial displacement distance H1 relative to the female sleeve 102a until the female sleeve 102a establishes a stable main current path with the metal layer S. At the same time, the voltage pin assembly 201b maintains no current contact under the action of the buffer spring 201e. S2: Connect the current pin assembly 201a of the main current unit 100 to an external constant current source to form a Force circuit, and connect the voltage pin assembly 201b to the Kelvin interface of the PCB board 202 to form a Sense circuit. S3: Inject a constant DC or pulse current into the metal layer S through the main current unit 100. At the same time, the voltage pin assembly 201b collects the no-current voltage drop signal on the surface of the metal layer S in a four-point method and sends the signal to the PCB board 202. The host computer electrically connected to the PCB board 202 calculates the real-time resistance. S4: Repeat step S4 during the power cycle and record the relative change in resistance. When the resistance exceeds the set threshold, the metal layer S is determined to have aged and failed, realizing online monitoring.

[0065] Step S1: Test system assembly and initial positioning. The purpose of this step is to establish a precise mechanical foundation for subsequent pressurization and measurement. The specific operations are as follows: 1. Place the device under test: First, place the crimp connector 101 under test stably on the test platform below the fixture system. When placing it, ensure that the metal layer S on the surface of the crimp connector 101 (chip) faces upwards, and that the surface is clean and free of oxide layer or contaminants to ensure good electrical contact.

[0066] 2. Stack the measuring components in sequence: Above the pressure fitting 101 to be tested, stack the measuring components in a strict order: Install the insulating bakelite 203: Place the lower end face of the insulating bakelite 203 stably on the metal layer S surface of the device under test. The first limiting hole 203a and the second limiting hole 203b on the insulating bakelite 203 should be initially aligned with the corresponding positions on the device. The core function of the insulating bakelite 203 is to provide mechanical support, electrical insulation, and precise positioning of the subsequent signal pins 201 and conductive copper pillars 102.

[0067] Installing PCB board 202 and signal pins 201: Place the PCB board 202, with the pre-soldered metal-layer S-signal measurement pins, onto the insulating bakelite 203. During operation, ensure that the contact end 201d of each signal pin 201 can smoothly pass through the first limiting hole 203a on the insulating bakelite 203. Simultaneously, the through hole 102d on the PCB board 202 must be aligned with the second limiting hole 203b on the insulating bakelite 203.

[0068] Installing the conductive copper block 103 and the conductive copper pillar 102: Finally, place the conductive copper block 103 on the PCB board 202. The connecting groove 103a on the bottom surface of the conductive copper block 103 must be aligned and in contact with the top of the male sleeve 102b of the retractable conductive copper pillar 102, which has been inserted into the through hole 102d of the PCB board 202 and the second limiting hole 203b of the insulating bakelite 203.

[0069] Forming common point contact: Through the above-mentioned precise stacking, it is finally ensured that the lower ends of the current pin group 201a, the voltage pin group 201b, and the lower end of the female sleeve 102a of the retractable conductive copper column 102 form stable and positionally determined physical contact points on the metal layer S surface of the pressure connector 101 to be tested.

[0070] Step S2: Applying pressure and establishing a stable electrical contact path. This step is key to achieving non-destructive and reliable measurement. The core of this step is to decouple mechanical pressure from electrical contact function through a stretchable structure.

[0071] 1. Applying pressure: Start the clamping system to drive its pressure end 301 to move downward. The pressure is transmitted to the conductive copper block 103 through the positive electrode plate 304.

[0072] 2. Action of the retractable conductive copper pillar 102: The conductive copper block 103 transmits pressure to the male sleeve 102b of the retractable conductive copper pillar 102 it contacts. The male sleeve 102b begins to displace downward relative to the female sleeve 102a, compressing the pressure spring 102c between them. Because the design ensures that the maximum elastic gap H2 between the male and female ends is greater than the maximum possible axial displacement H1 between the lower end face of the conductive copper block 103 and the upper end face of the PCB board 202 (i.e., H2>H1), the pressure spring 102c is fully compressed, but the bottom of the male sleeve 102b does not impact the inner bottom surface of the female sleeve 102a. This allows the female sleeve 102a, under its own weight and the small reaction force of the spring, to contact the surface of the metal layer S with a gentle and constant pressure, thereby establishing a stable, low-resistance main current path while avoiding mechanical damage to the chip surface from hard impacts.

[0073] 3. Status of signal pin 201: Simultaneously, under the action of the internal buffer spring 201e, the contact end 201d of the signal measurement pin for metal layer S also maintains stable contact with metal layer S. Due to the retractable design of the signal pins 201 themselves, they do not bear the main mechanical pressure, but only maintain a good electrical contact state, preparing for high-precision voltage measurement.

[0074] Step S3: Connect the measurement circuit. After the mechanical pressure stabilizes, make the electrical connection to establish a measurement system based on the four-point method (Kelvin connection).

[0075] 1. Connect the Force circuit: Use leads to connect the current pin group 201a on PCB board 202 to a high-precision, high-stability external constant current source. This circuit is called the Force circuit and is responsible for injecting excitation current into the metal layer S under test.

[0076] 2. Connect the Sense circuit: Using another set of independent leads, connect the voltage pin group 201b on PCB 202 to the high input impedance Kelvin detection interface on PCB 202. This circuit is called the Sense circuit and is specifically used to acquire voltage signals. Due to its extremely high input impedance, the current flowing through this circuit is negligible, thus enabling voltage measurement under no current (or micro-current) conditions.

[0077] Step S4: Single resistance measurement and data acquisition. This step is the core operation of each monitoring cycle and is used to obtain the real-time resistance value of the metal layer S.

[0078] 1. Current Excitation: Through the connected Force circuit, an external constant current source is controlled to inject a preset-sized, highly stable constant DC current (or pulse current) I into the main current unit 100. The path of this current is: constant current source → current pin group 201a → metal layer S → retractable conductive copper pillar 102 → conductive copper block 103 → back to constant current source.

[0079] 2. Voltage Signal Acquisition: When current I flows through metal layer S, a voltage drop is generated along the current path. At this time, the open-circuit voltage difference between two measurement points on the surface of metal layer S is accurately acquired using a four-point method via the connected Sense circuit and voltage pin group 201b. Since the Sense circuit draws almost no current, the measured voltage drop eliminates the influence of lead resistance and contact resistance, purely reflecting the voltage drop generated by the metal layer S itself under the excitation current I.

[0080] 3. Signal Processing and Resistance Calculation: The acquired weak analog voltage signal is preprocessed by the signal conditioning circuit (such as amplification and filtering) on ​​PCB board 202, and then converted into a digital signal by the data acquisition system (such as an AD converter) and transmitted to the host computer (computer or dedicated controller). The host computer calculates the resistance value of the metal layer S in real time according to Ohm's law.

[0081] Step S5: Power Cycling and Aging Status Determination. This step enables continuous and automated monitoring throughout the entire device lifetime accelerated testing process.

[0082] 1. Continuous Cyclic Monitoring: During the operation of the power cycling test equipment, the system continuously and periodically repeats step S4. Each repetition records the current cycle number (or time, device junction temperature, etc.) and the calculated real-time resistance value.

[0083] 2. Data Processing and Trend Analysis: The host computer compares each measured resistance value R with the initial resistance value R0 and calculates its relative change: R0 = (R - R0) / R0. This relative change is a key parameter characterizing the aging degree of the metal layer S.

[0084] 3. Failure Determination: The system presets an aging failure threshold (e.g., R0 > 5% or 10%). During power cycling, the value of R0 is monitored in real time. Once the relative change in resistance is detected to continuously exceed the set threshold, the host computer can determine that the metal layer S of the pressure connector 101 under test has failed due to aging, and trigger an alarm, record failure data, or stop the test.

[0085] 4. Achieve online monitoring: Through the above complete closed-loop process, the present invention achieves online, in-situ, and real-time monitoring and evaluation of the health status of the metal layer S while power cycling stress is applied, providing direct and effective data support for device reliability research and lifetime prediction.

[0086] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A device for monitoring the metal layer of a press-fit IGBT device, characterized in that: include, The main current unit (100) includes a conductive copper pillar (102) electrically connected to the pressure connector (101) under test. The signal sampling unit (200) includes a plurality of signal pins (201) connected to the pressure connector (101) to be tested, and a PCB board (202) connected to the signal pins (201). The signal sampling unit (200) and the main current unit (100) are in point contact on the metal layer (S) on the upper end face of the pressure connector (101) under test, and the current path and the sampling path are independent of each other.

2. The monitoring device for the metal layer of the crimped IGBT device as described in claim 1, characterized in that: The conductive copper pillar (102) includes a female sleeve (102a), a male sleeve (102b), and a pressure spring (102c). The female sleeve (102a) is in contact with the metal layer (S) on the upper end face of the pressure fitting (101) to be tested; The male sleeve (102b) is movably connected to the female sleeve (102a); The pressure spring (102c) is connected between the female sleeve (102a) and the male sleeve (102b); The PCB board (202) is provided with a through hole (102d) that penetrates the conductive copper pillar (102).

3. The metal layer monitoring device for press-fit IGBT devices as described in claim 1 or 2, characterized in that: The signal pins (201) are divided into current pin groups (201a) and voltage pin groups (201b), and each group has at least two pins. The current pin group (201a) is in contact with the metal layer (S), and the voltage pin group (201b) is in contact with the metal layer (S) and is electrically connected to the main current unit (100).

4. The metal layer monitoring device for press-fit IGBT devices as described in claim 3, characterized in that: The signal sampling unit (200) also includes insulating bakelite (203), the upper end face of which abuts against the PCB board (202), and the lower end face is stacked on the surface of the pressure fitting (101) to be tested. The insulating bakelite (203) is provided with a first limiting hole (203a) that penetrates the signal pin (201) and a second limiting hole (203b) that penetrates the conductive copper pillar (102). The insulating bakelite (203) is provided in several groups on the surface of the pressure fitting (101) to be tested, and each group of insulating bakelite (203) is provided with at least one conductive copper pillar (102).

5. The metal layer monitoring device for press-fit IGBT devices as described in claim 4, characterized in that: The main current unit (100) also includes a conductive copper block (103) connected to a plurality of conductive copper pillars (102) in an insulating bakelite (203). The conductive copper block (103) is provided with a connecting groove (103a) that is connected to the conductive copper column (102), and the male sleeve (102b) is connected to the top of the inner surface of the connecting groove (103a). The lower end face of the conductive copper block (103) has an axial displacement distance H1 with respect to the PCB board (202), and the male sleeve (102b) and the female sleeve (102a) have an elastic gap H2, wherein H2 > H1.

6. The metal layer monitoring device for press-fit IGBT devices as described in claim 5, characterized in that: The signal pin (201) includes a fixed end (201c), a contact end (201d), and a buffer spring (201e). The fixed end (201c) passes through the first limiting hole (203a) and is fixedly connected to the lower end face of the PCB board (202); The contact end (201d) is movably connected to the fixed end (201c) and is in contact with the metal layer (S) of the pressure fitting (101) to be tested; The buffer spring (201e) is connected between the fixed end (201c) and the contact end (201d).

7. The metal layer monitoring device for press-fit IGBT devices as described in any one of claims 1-2 and 4-6, characterized in that: The test crimping component (101) is provided with a protective shell (204) on the outside, and the protective shell (204) is provided with a limiting port (205) that penetrates the insulating bakelite (203).

8. A clamping system, characterized in that: The device includes the metal layer monitoring equipment for press-fit IGBT devices as described in any one of claims 1-2 and 5-6, and further includes, The frame (300) includes a pressure end (301) and a support end (302). At least two test platforms are provided between the pressure end (301) and the support end (302). A positive electrode plate (304) is connected between the pressure end (301) and the upper test platform, and a negative electrode plate (305) is connected between the support end (302) and the lower test platform. The lower end face of the test platform located above is connected to the conductive copper block (103), and the upper end face of the test platform located below is in contact with the lower end face of the pressure fitting (101) to be tested.

9. The clamping system as claimed in claim 8, characterized in that: The test platform is provided with a first positioning hole (306), the conductive copper block (103) is provided with a second positioning hole (307), and a positioning post (308) is provided between the first positioning hole (306) and the second positioning hole (307).

10. A monitoring method, characterized in that: Includes the following steps: S1: Place the pressure fitting to be tested (101) on the test platform below the fixture system with the metal layer (S) of the device facing upward; stack the insulating bakelite (203), PCB board (202), and conductive copper block (103) on top of the device in sequence, and make the lower ends of the current pin group (201a), voltage pin group (201b) and conductive copper pillar (102) form a common point contact on the surface of the metal layer (S); S2: The pressure end (301) of the drive clamp system moves downward, the positive plate (304) pushes the conductive copper block (103), the male sleeve (102b) of the conductive copper column (102) compresses the pressure spring (102c) and generates an axial displacement distance H1 relative to the female sleeve (102a) until the female sleeve (102a) establishes a stable main current path with the metal layer (S), while the voltage pin group (201b) remains in no-current contact under the action of the buffer spring (201e); S3: Connect the current pin group (201a) of the main current unit (100) to an external constant current source to form a Force circuit, and connect the voltage pin group (201b) to the Kelvin interface of the PCB board (202) to form a Sense circuit. S4: A constant DC or pulse current is injected into the metal layer (S) through the main current unit (100). At the same time, the voltage pin group (201b) collects the no-current voltage drop signal on the surface of the metal layer (S) in a four-point method and sends the signal to the PCB board (202). The real-time resistance is calculated by the host computer that is electrically connected to the PCB board (202). S5: Repeat step S4 during the power cycle, record the relative change in resistance, and determine the metal layer (S) aging failure when the resistance exceeds the set threshold, thus realizing online monitoring.

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