An apparatus and method for evaluating the degradation of a welded joint under the combined effects of temperature and pressure

Abstract

The application discloses a kind of temperature pressure coupling under the evaluation device and method of life degradation of welded joint, the device includes shell, pressure rod, heating system, pressure sensing system, cushion block, control system;Pressure rod is used to apply pressure to the sample to be measured;Heating system, heat insulating block, pressure sensing system, cushion block are installed in shell, and are coaxially installed with pressure rod, cushion block is located below pressure rod, pressure sensing system is located below cushion block, heat insulating block is located below pressure sensing system;Heating system is installed in the bottom of shell, and the inside of heating system is the cavity for placing the sample to be measured;Pressure sensing system is used to detect the pressure applied by pressure rod, heating system is used to heat the sample to be measured, control system is used to control pressure sensing system, heating system and receive the data of pressure sensing system, heating system.The application can simulate the service environment of welded joint under coupling condition, and provide data support for studying the life degradation of welded joint.

Description

Technical Field

[0001] This invention relates to the field of power semiconductor material performance testing technology, and in particular to an evaluation device and method for the lifetime degradation of welded joints under temperature-pressure coupling. Background Technology

[0002] As a critical interconnection between the chip and substrate, and between the substrate and heat dissipation structure within power semiconductor devices, the performance of the weld joint directly determines the overall electrothermal transfer efficiency, mechanical reliability, and service life of the device. In practical applications, power semiconductor devices often simultaneously withstand Joule heating generated by current, thermal loads caused by changes in ambient temperature, and mechanical constraints and thermal mismatch stresses imposed by the packaging structure. This is especially true for press-fit power devices, which endure complex conditions of multi-field coupling of pressure and thermal stress over extended periods. Under these conditions, the microstructure evolution, interface reactions, and damage accumulation behavior of the weld joint differ significantly from those under single thermal cycles or mechanical vibration loads. Currently, high-temperature reliability assessments of weld joints for power semiconductor devices often employ individual high-temperature storage, thermal cycling, or shear tests, which are insufficient to realistically simulate the coupled environment of simultaneous temperature and pressure during actual service. Therefore, a testing device and method capable of simulating temperature-pressure coupled conditions are urgently needed to accurately assess the lifetime degradation behavior of weld joints in power semiconductor devices. Summary of the Invention

[0003] Purpose of the invention: To address the above-mentioned shortcomings, the present invention provides an apparatus and method for evaluating the life degradation of welded joints under temperature-pressure coupling.

[0004] Technical Solution: To solve the above problems, this invention employs an assessment device for the life degradation of welded joints under temperature-pressure coupling, comprising a housing, a pressure rod, a heating system, a pressure sensing system, a pad, and a control system. The pressure rod is movably mounted on the housing, with one end inside the housing and the other end above it. The heating system, heat insulation block, pressure sensing system, and pad are all installed inside the housing and coaxially with the pressure rod. The pad is located below the pressure rod, the pressure sensing system is located below the pad, and the heat insulation block is located below the pressure sensing system. The heating system is installed at the bottom inside the housing, with an inner cavity for placing the sample to be tested. The pressure sensing system is used to detect the pressure applied by the pressure rod, the heating system is used to heat the sample to be tested, and the control system is used to control the pressure sensing system and the heating system, as well as receive data from the pressure sensing system and the heating system.

[0005] Furthermore, the outer casing includes a base plate, a support plate mounted on the base plate, an upper cover plate mounted on the support plate, and a pressure rod mounted on the upper cover plate.

[0006] Furthermore, the pressure rod is a hexagonal bolt, and a screw hole is opened in the center of the upper cover plate, into which the pressure rod is installed.

[0007] Furthermore, the lower surface of the upper cover plate is provided with guide posts, and the heat insulation block, pressure sensing system, and pad block are provided with through holes for the guide posts to pass through.

[0008] Furthermore, the heat insulation block is made of high-strength microporous heat insulation material.

[0009] Furthermore, the pressure sensing system includes a pressure sensor and a signal processing module. The pressure sensor is used to detect the pressure on the sample to be tested, and the signal processing module is used to transmit the pressure data to the control system.

[0010] Furthermore, the heating system includes an electromagnetic induction heating coil and a temperature feedback device. The heating coil has interfaces at both ends for connecting to a power source, and the temperature feedback device is used to monitor the temperature of the heating coil and transmit the data to the control system.

[0011] Furthermore, the temperature feedback device is a thermocouple or an infrared thermometer.

[0012] The present invention also provides an evaluation method for the above-mentioned evaluation device, comprising the following steps:

[0013] Step 1: Place the sample to be tested in the cavity inside the heating system, so that the lower surface of the heat insulation block is in contact with the upper surface of the sample to be tested.

[0014] Step 2: Press down the pressure bar to apply a preset pressure to the sample to be tested;

[0015] Step 3: Start the heating system and heat the sample to be tested according to the preset heating and cooling curve;

[0016] Step 4: The control system records the pressure-time curve, temperature-time curve, and sample failure time of the sample under temperature-pressure coupling.

[0017] Step 5: Repeat steps 1 to 4 to obtain the failure time of the test sample under different pressure and temperature conditions, and establish a pressure-temperature-test sample lifetime relationship model.

[0018] Furthermore, the sample failure time is the time when the pressure sensor detects a sudden change in pressure.

[0019] Beneficial effects: Compared with the prior art, the significant advantages of this invention are that it can simultaneously apply temperature and pressure loads, realistically simulating the service environment of welded joints under coupled conditions; it adopts electromagnetic induction heating, which has a fast heating speed and precise temperature control, and the non-contact heating avoids interference from the heating element on sample deformation; through the design of heat insulation block and guide column, it effectively protects the pressure sensing system from the influence of high temperature, while ensuring coaxial pressure transmission and improving test accuracy; it has a simple structure, is easy to operate, and is applicable to welded joint samples of various sizes. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the evaluation device of the present invention;

[0021] Figure 2 This is a schematic diagram of the evaluation method of the present invention. Detailed Implementation

[0022] like Figure 1 As shown, this embodiment of an assessment device for the life degradation of welded joints under temperature-pressure coupling includes a base plate 1, a support plate 2, a top cover plate 3, a pressure rod 4, a heating system 5, a heat insulation block 7, a pressure sensing system 8, a pad 9, and a control system. The base plate 1 is a rectangular thick plate made of heat-resistant steel, with a flat upper surface for placing samples. Two support plates 2 are vertically welded to both sides of the base plate 1. The top cover plate 3 is horizontally welded to the top of the two support plates 2, forming a rigid frame shell for mounting the assessment structure. The pressure rod 4 is a hexagonal bolt; a screw hole is opened in the center of the top cover plate 3, and the pressure rod 4 is installed in this screw hole. Rotation causes the hexagonal bolt to move up and down.

[0023] The heating system 5, heat insulation block 7, pressure sensing system 8, and pad 9 are all installed inside the frame housing and are coaxially mounted with the pressure rod 4. Pad 9 is located below the pressure rod 4, pressure sensing system 8 is located below pad 9, and heat insulation block 7 is located below pressure sensing system 8. The heat insulation block 7, pressure sensing system 8, and pad 9 are stacked and contacted sequentially. The heating system 5 is installed at the bottom of the housing. The inner side of the heating system 5 is a cavity for placing the sample 6 to be tested. After the sample 6 is installed in the cavity, its upper surface contacts the lower surface of the heat insulation block 7. The heat insulation block 7 is used to isolate the sample to be tested from the pressure sensing system 8. The heat insulation block 7 is made of alumina ceramic or microporous insulating material.

[0024] The lower surface of the upper cover plate 3 is provided with guide posts (not shown in the figure). The guide posts are annular or columnar structures. The pad 9, pressure sensing system 8, and heat insulation block 7 all have grooves or through holes that cooperate with the guide posts, so that they can move along the axial direction of the guide posts to ensure that the pressure transmission axis coincides with the sample axis.

[0025] The pressure sensing system 8 includes a pressure sensor and a signal processing module. The pressure sensor detects the pressure on the sample, and the signal processing module transmits the pressure data to the control system. The heating system 5 includes a heating coil and a temperature feedback device. The heating coil has interfaces at both ends for connecting to a power source. After connecting to a high-frequency power supply, it heats the sample through electromagnetic induction. The temperature feedback device monitors the temperature of the heating coil and transmits the data to the control system. The control system controls the pressure sensing system 8 and the heating system 5, and receives data from both systems.

[0026] like Figure 2 As shown, the present invention also provides an evaluation method for the above-mentioned evaluation device, comprising the following steps:

[0027] Step 1: Place the sample to be tested in the cavity inside the heating system 5. The lower surface of the heat insulation block 7 is in contact with the sample to be tested 6, and the sample to be tested 6 is also coaxial with the pressure rod 4.

[0028] Step 2: Rotate the hexagonal bolt to move it downwards to generate a preset pressure. The pressure of the pressure rod 4 is transmitted to the sample 6 to be tested through the heat insulation block 7, the pressure sensing system 8, and the pad 9.

[0029] Step 3: Start the heating system 5 to heat the sample to be tested according to the preset heating and cooling curve. The sample to be tested is heated by the heating coil. Thermocouples or infrared thermometers are used to monitor the temperature of the heating coil and transmit the data to the control system.

[0030] Step 4: The control system records the pressure-time curve, temperature-time curve, and sample failure time of the sample under temperature-pressure coupling. The welded joint under test deteriorates under pressure-temperature coupling, exhibiting failure modes such as voids, cracks, or delamination. The monitored pressure will show a significant decrease; therefore, the time when the pressure changes abruptly is counted as the sample failure time.

[0031] Step 5: Repeat steps 1 to 4 to obtain the failure time of the test sample under different pressure and temperature conditions, and establish a pressure-temperature-test sample lifetime relationship model.

[0032] In step 4, the test sample can be periodically removed and ultrasonically scanned to obtain its surface morphology and performance data, thereby analyzing the effects of temperature, pressure and action time on the properties of the test sample, such as voids and interconnect strength.

[0033] This invention can simultaneously apply temperature and pressure loads, realistically simulating the service environment of welded joints under coupled conditions. It employs electromagnetic induction heating, which offers rapid heating, precise temperature control, and non-contact heating to avoid interference from the heating element on sample deformation. The design of heat insulation blocks and guide pillars effectively protects the pressure sensing system from high temperatures while ensuring coaxial pressure transmission, thus improving testing accuracy. The invention features a simple structure, convenient operation, and is applicable to welded joint samples of various sizes.

Claims

1. A device for evaluating the life degradation of welded joints under temperature-pressure coupling, characterized in that, The system includes a housing, a pressure rod (4), a heating system (5), a pressure sensing system (8), a pad (9), and a control system. The pressure rod (4) is movably mounted on the housing, with one end inside the housing and the other end above it. The heating system (5), the heat insulation block (7), the pressure sensing system (8), and the pad (9) are all installed inside the housing and are coaxially mounted with the pressure rod (4). The pad (9) is located below the pressure rod (4), the pressure sensing system (8) is located below the pad (9), and the heat insulation block (7) is located below the pressure sensing system (8). The heating system (5) is installed at the bottom inside the housing, and the inside of the heating system (5) is a cavity for placing the sample to be tested. The pressure sensing system (8) is used to detect the pressure applied by the pressure rod (4), the heating system (5) is used to heat the sample to be tested, and the control system is used to control the pressure sensing system (8), the heating system (5), and receive data from the pressure sensing system (8) and the heating system (5).

2. The evaluation apparatus as described in claim 1, characterized in that, The outer shell includes a base plate (1), a support plate (2) mounted on the base plate (1), an upper cover plate (3) mounted on the support plate (2), and a pressure rod (4) mounted on the upper cover plate (3).

3. The evaluation apparatus as described in claim 2, characterized in that, The pressure rod (4) is a hexagonal bolt, and the upper cover plate (3) has a screw hole in the center, and the pressure rod (4) is installed in the screw hole.

4. The evaluation apparatus as described in claim 2, characterized in that, The lower surface of the upper cover plate (3) is provided with guide posts, and the heat insulation block (7), pressure sensing system (8), and pad (9) have through holes for the guide posts to pass through.

5. The evaluation apparatus as described in claim 1, characterized in that, The heat insulation block (7) is made of high-strength microporous heat insulation material.

6. The evaluation apparatus as claimed in claim 1, characterized in that, The pressure sensing system (8) includes a pressure sensor and a signal processing module. The pressure sensor is used to detect the pressure on the sample to be tested, and the signal processing module is used to transmit the pressure data to the control system.

7. The evaluation apparatus as claimed in claim 1, characterized in that, The heating system (5) includes an electromagnetic induction heating coil and a temperature feedback device. The heating coil has interfaces at both ends for connecting to a power source. The temperature feedback device is used to monitor the temperature of the heating coil and transmit the data to the control system.

8. The evaluation apparatus as claimed in claim 7, characterized in that, The temperature feedback device is a thermocouple or an infrared thermometer.

9. An evaluation method for the evaluation apparatus as described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Place the sample to be tested in the cavity inside the heating system (5) so that the lower surface of the heat insulation block (7) contacts the upper surface of the sample to be tested. Step 2: Press down the pressure bar (4) to apply a preset pressure to the sample to be tested; Step 3: Start the heating system (5) and heat the sample to be tested according to the preset heating and cooling curve; Step 4: The control system records the pressure-time curve, temperature-time curve, and sample failure time of the sample under temperature-pressure coupling. Step 5: Repeat steps 1 to 4 to obtain the failure time of the test sample under different pressure and temperature conditions, and establish a pressure-temperature-test sample lifetime relationship model.

10. The evaluation method as described in claim 9, characterized in that, The sample failure time is the time when the pressure sensor detects a sudden change in pressure.

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