An experimental device and method for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue

Abstract

The present invention relates to an experimental device and method for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue, and the experimental device includes: an electromagnetic heating system, a liquid nitrogen cooling system, a dry ice cooling system, a high-speed camera system, a USB data acquisition card and a terminal computer. The present application heats the solder joint by an electromagnetic heating system, and cools the solder joint by a liquid nitrogen cooling system or a dry ice cooling system, and can complete a thermal cycle in a relatively short time, greatly improving the experimental efficiency. The high-speed camera system can monitor and record the solder joint state and the cracking path of the crack in real time; dry ice can effectively remove the oxide film on the surface of the solder joint, thereby eliminating the influence of the cracking of the oxide film on the solder joint cracking; the solder joint is cooled by a liquid nitrogen cooling system, and under the condition that the heating temperature and the cooling temperature are unchanged, it can be effectively determined according to the crack generation form whether the solder joint cracking is caused by cracks generated inside the solder joint or by cracking of the oxide film.

Description

Technical Field

[0001] The invention relates to the technical field of research on the mechanism of solder crack generation, and in particular to an experimental device and method for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue. Background Art

[0002] In the context of the booming electronics industry today, solder joints and solders are key connecting parts in electronic devices, and their reliability directly affects the performance and life of electronic devices. As electronic products continue to move towards miniaturization, high performance and multifunctionality, solder joints and solders often face the harsh environment of rapid thermal fatigue in practical applications. However, there are still many uncertainties about the mechanism of crack generation in solder joints and solders under such an environment. On the one hand, some people believe that the cracking of solder and solder oxide film is an important cause of crack generation. During the rapid thermal fatigue process, the surface of solder joints and solders will react with the surrounding environment to form an oxide film. Since the thermal expansion coefficient of the oxide film is often different from that of the solder and solder body, when the temperature changes rapidly, the oxide film will be subjected to greater stress. Once this stress exceeds the strength limit of the oxide film, the oxide film will crack. The cracking of the oxide film is very likely to destroy the integrity of the solder and solder surface, causing stress to concentrate at the interface between the oxide film and the solder and solder, thereby inducing cracks inside the solder and solder. However, there is a lack of in-depth and systematic research on the specific formation process and characteristics of the oxide film and its exact relationship with crack generation, and there is no clear experimental evidence to support this view. On the other hand, many researchers believe that internal stress is the key factor leading to cracking in solder and solder joints. Rapid thermal fatigue can cause uneven thermal expansion and contraction in solder joints and solders, thereby causing internal stress. The generation of this internal stress may be due to the mismatch of thermal expansion coefficients between solder and solder joints and connected components, and between different grains in solder and solder joints. When the internal stress exceeds the yield strength of solder and solder joints, cracks will occur in solder and solder joints. However, there is no mature technology and method for the specific generation mechanism of internal stress, its distribution inside solder and solder joints, and how to accurately measure and evaluate the impact of internal stress on crack generation.

[0003] At present, the existing thermal fatigue test equipment can usually only simulate temperature changes in a relatively simple way, and cannot accurately control and monitor the formation and changes of the oxide film, as well as the stress state inside the solder and solder joints. At the same time, the existing observation methods are also difficult to clearly capture the early stages and microscopic processes of crack generation, making it difficult for experimenters to accurately determine whether the cracks are caused by the cracking of the oxide film or by internal stress. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, one of the purposes of the present invention is to provide an experimental device for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue, so as to solve the problem that the existing experimental device cannot accurately determine whether the crack is caused by the cracking of the oxide film or the internal stress. The second purpose is to provide an experimental method for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue.

[0005] To achieve the above-mentioned and other related purposes, the present invention provides an experimental device for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue, comprising:

[0006] Electromagnetic heating system for heating solder joints and solder samples;

[0007] A liquid nitrogen cooling system, used to cool the solder joints and solder samples;

[0008] A dry ice cooling system, used to remove oxide films on the surfaces of the solder joints and solder samples and to cool the solder joints and solder samples;

[0009] A high-speed camera system, used to photograph and record the state changes of the solder joints and solder samples;

[0010] A USB data acquisition card, the electromagnetic induction heating system, the liquid nitrogen cooling system and the dry ice cooling system are all connected to the USB data acquisition card;

[0011] The terminal computer, the USB data acquisition card and the high-speed camera system are connected to the terminal computer, and the terminal computer is provided with programming software.

[0012] Optionally, the electromagnetic heating system includes a heating platform, a high-frequency induction heating machine and an induction coil, the induction coil is arranged around the heating platform, the high-frequency induction heating machine is connected to the induction coil, and the heating platform is used to carry the solder joint and the solder sample.

[0013] Optionally, the electromagnetic induction heating system further comprises a temperature detection element, which is used to detect the temperature of the solder joints and solder samples on the heating platform. An intelligent temperature transmitter is provided between the temperature detection element and the USB data acquisition card, and the intelligent temperature transmitter is used to amplify the temperature signal of the temperature detection element.

[0014] Optionally, the electromagnetic induction heating system further comprises a DC switching power supply, and the DC switching power supply is connected between the high-frequency induction heating machine and the USB data acquisition card.

[0015] Optionally, the liquid nitrogen cooling system includes a first control module, a first power switch, a liquid nitrogen tank, a spray head and a liquid nitrogen pipeline, the first control module is electrically connected to the USB data acquisition card, the first power switch is electrically connected to the first control module, the liquid nitrogen tank is electrically connected to the first power switch, the liquid nitrogen pipeline is connected to the liquid nitrogen tank, and the spray head is connected to the liquid nitrogen pipeline.

[0016] Optionally, the liquid nitrogen tank is provided with a pressure regulator, and the pressure regulator is used to adjust the spraying pressure of the liquid nitrogen in the liquid nitrogen tank to adjust the spraying rate of the liquid nitrogen.

[0017] Optionally, the dry ice cooling system includes a second control module, a second power switch, an air compressor, a dry ice cabinet, a dry ice pipe and a spray gun, the second control module is electrically connected to the USB data acquisition card, the second power switch is electrically connected to the second control module, the air compressor is electrically connected to the second power switch, the dry ice cabinet is connected to the air compressor, the dry ice pipe is connected to the dry ice cabinet, and the spray gun is connected to the dry ice pipe.

[0018] Optionally, an air filter is provided between the air compressor and the dry ice cabinet, and the air filter is used to filter impurities in the air input into the dry ice cabinet by the air compressor.

[0019] Optionally, the high-speed camera system includes a high-speed camera and control shooting software, the high-speed camera is used to shoot the solder joints and solder samples, the control shooting software is installed on the terminal computer, and the control shooting software is used to control the shooting parameters of the high-speed camera and display and save the captured images in real time.

[0020] The present invention also provides an experimental method for studying the mechanism of solder joints and solder cracks under rapid thermal fatigue, which is applied to the experimental device for studying the mechanism of solder joints and solder cracks under rapid thermal fatigue as described above. The experimental method comprises:

[0021] Fix the solder joint and solder sample on a heating table;

[0022] Set the preset heating temperature and preset cooling temperature, preset heating time and heating and heat preservation time, preset cooling time and cooling and heat preservation time on the programming software of the terminal computer, and select the cooling system on the terminal computer;

[0023] The electromagnetic heating system heats the solder joint and the solder sample for a preset heating time, so that the solder joint and the solder sample reach a preset heating temperature, and maintains the current temperature and the heating and heat preservation time;

[0024] If the dry ice cooling system is selected, the terminal computer controls the electromagnetic heating system to be turned off and the dry ice cooling system to be turned on. The dry ice cooling system cools the solder joints and solder samples for a preset cooling time, so that the solder joints and solder samples reach the preset cooling temperature, and maintain the current temperature and the cooling and heat preservation time;

[0025] If the liquid nitrogen cooling system is selected, the terminal computer controls the electromagnetic heating system to be turned off and the liquid nitrogen cooling system to be turned on. The liquid nitrogen cooling system cools the solder joints and solder samples for a preset cooling time, so that the solder joints and solder samples reach the preset cooling temperature, and maintain the current temperature and the cooling and holding time;

[0026] The state changes of solder joints and solder are captured by a high-speed camera system.

[0027] As described above, the present invention has the following beneficial effects: the present application heats the solder joint and the solder sample by an electromagnetic heating system, and cools the solder joint and the solder sample by a liquid nitrogen cooling system or a dry ice cooling system, and can complete a thermal cycle in a relatively short time, which greatly improves the experimental efficiency compared to the traditional thermal cycle; the high-speed camera system can observe and record the solder joint state and the cracking path of the crack in real time, and clearly observe the crack generation process; by adopting a dry ice cooling system to cool the solder joint, the dry ice can effectively remove the oxide film on the surface of the solder joint, thereby eliminating the influence of the cracking of the oxide film on the solder joint cracking; by cooling the solder joint by a liquid nitrogen cooling system, under the condition that the heating temperature and the cooling temperature are unchanged, it can be effectively determined whether the solder joint cracking is caused by cracks generated inside the solder joint or by cracking of the oxide film according to the crack generation form. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Shown is a schematic diagram of the structure of an experimental device for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue shown in an embodiment of the present application;

[0029] Figure 2 The experimental system for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue shown in the embodiment of the present application is shown;

[0030] Figure 3 The flowchart shows an experimental method for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue according to an embodiment of the present application.

[0031] Description of Reference Numerals

[0032] Electromagnetic heating system 1, heating table 101, high-frequency induction heating machine 102, induction coil 103, temperature detection element 104, intelligent temperature transmitter 105, DC switching power supply 106, liquid nitrogen cooling system 2, first control module 201, first power switch 202, liquid nitrogen tank 203, spray head 204, liquid nitrogen pipeline 205, pressure regulator 206, dry ice cooling system 3, second control module 301, second power switch 302, air compressor 303, dry ice cabinet 304, dry ice pipeline 305, spray gun 306, air filter 307, high-speed camera 4, USB data acquisition card 5, terminal computer 6. DETAILED DESCRIPTION

[0033] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0034] See also Figures 1 to 3 It should be noted that the diagrams provided in the present embodiment only illustrate the basic concept of the present invention in a schematic manner, so the diagrams only show the components related to the present invention rather than drawing according to the number, shape and size of the components in actual implementation. The type, quantity and proportion of each component in actual implementation can be changed at will, and the component layout type may also be more complicated. The structures, proportions, sizes, etc. shown in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions that the present invention can be implemented, so they have no technical substantive significance. Any modification of the structure, change of the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of the relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0035] Before describing the embodiments of the present invention in detail, the application environment of the present invention is described first. The technology of the present invention is mainly applied to the technical field of research on the mechanism of solder crack generation. The present invention is used to solve the problem that the existing experimental device cannot accurately determine whether the crack is caused by the cracking of the oxide film or the internal stress.

[0036] Please combine Figure 1 to Figure 2As shown, the present invention provides an experimental device for studying the generation mechanism of solder joint and solder crack under rapid thermal fatigue.

[0037] In an exemplary embodiment of the present application, an experimental device for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue includes: an electromagnetic heating system 1, used to heat the solder joint and solder samples; a liquid nitrogen cooling system 2, used to cool the solder joint and solder samples; a dry ice cooling system 3, used to remove the oxide film on the surface of the solder joint and solder samples and cool the solder joint and solder samples; a high-speed camera system, used to photograph and record the state changes of the solder joint and solder samples; a USB data acquisition card 5, the electromagnetic induction heating system, the liquid nitrogen cooling system 2 and the dry ice cooling system 3 are all connected to the USB data acquisition card 5; a terminal computer 6, the USB data acquisition card 5 and the high-speed camera system are all connected to the terminal computer 6, and the terminal computer 6 is provided with programming software.

[0038] In this embodiment, programming software is used to control the entire system and select a cooling mode with high control accuracy and short lag time. The electromagnetic heating system 1 is used to heat the solder joint and the solder sample, so that the solder joint can be heated to a preset temperature in a relatively short time. The liquid nitrogen cooling system 2 or the dry ice cooling system 3 is used to cool the solder joint and the solder sample, so that the solder joint can be cooled to a preset temperature in a relatively short time. The electromagnetic heating system 1 and the liquid nitrogen cooling system 2 or the dry ice cooling system 3 are combined, so that the solder joint can complete a thermal cycle in a relatively short time. Traditional thermal cycles generally take more than one hundred hours to produce phenomena, which consumes a lot of time. The experimental device proposed in this application can achieve the same effect in a few hours or dozens of hours, which greatly improves the experimental efficiency compared to traditional thermal cycles. In addition, the procurement cost of traditional thermal fatigue test equipment is relatively high. By adopting the experimental device shown in the embodiment of this application, the equipment purchase cost can be effectively reduced, thereby reducing the experimental cost. This embodiment can observe and record the state of the solder joint and the cracking path of the crack in real time through the high-speed camera system, and clearly observe the crack generation process; by adopting the dry ice cooling system 3 to cool the solder joint, the dry ice can effectively remove the oxide film on the surface of the solder joint, thereby eliminating the influence of the solder joint crack caused by the cracking of the oxide film; by cooling the solder joint through the liquid nitrogen cooling system 2, under the condition that the heating temperature and the cooling temperature are unchanged, it can be effectively determined according to the crack generation form whether the solder joint crack is caused by cracks generated inside the solder joint or by cracks caused by the cracking of the oxide film.

[0039] In an exemplary embodiment of the present application, the electromagnetic heating system 1 includes a heating table 101, a high-frequency induction heating machine 102 and an induction coil 103. The induction coil 103 is arranged around the heating table 101, the high-frequency induction heating machine 102 is connected to the induction coil 103, and the heating table 101 is used to carry solder joints and solder samples.

[0040] In this embodiment, the heating platform 101 is made of stainless steel, which has excellent corrosion resistance and mechanical strength, and the solder joint to be heated is fixed on the heating platform 101. The induction coil 103 wraps the heating platform 101, and the high-frequency induction heating machine 102 passes a high-frequency current into the induction coil 103. When the high-frequency current passes through the induction coil 103, an alternating high-frequency magnetic field is formed around it. This magnetic field is the medium for energy transfer during the induction heating process and can convert electrical energy into thermal energy; when the high-frequency magnetic field acts on the heating platform 101, an induced current (eddy current) is generated inside it. Since the resistance of the metal is very low, this induced current is similar to a short-circuit current, which will generate a large amount of heat energy inside the metal, thereby achieving heating, and then the solid-solid heat exchange between the heating platform 101 and the solder joint is used to heat the solder joint.

[0041] In an exemplary embodiment of the present application, the electromagnetic induction heating system also includes a temperature detection element 104, which is used to detect the temperature of the solder joints and solder samples on the heating platform 101. An intelligent temperature transmitter 105 is provided between the temperature detection element 104 and the USB data acquisition card 5, and the intelligent temperature transmitter 105 is used to amplify the temperature signal of the temperature detection element 104.

[0042] In this embodiment, the temperature detection element 104 is a K-type thermocouple, which is arranged on the heating platform 101 to monitor the temperature of the solder joint on the heating platform 101 in real time; the intelligent temperature transmitter 105 is used to linearly amplify the temperature signal of the K-type thermocouple, and the temperature signal is transmitted to the USB data acquisition card 5. The USB data acquisition card 5 transmits the real-time collected temperature signal as a feedback signal to the terminal computer 6. After the computer runs the programming software, the calculation result is fed back to the USB data acquisition card 5 to achieve the purpose of controlling the power of the high-frequency induction heater 102 and the temperature of the heating platform 101. The advantage of using the intelligent temperature transmitter 105 in this embodiment is that it adopts magnetic and electric isolation technology, has good stability, strong anti-interference ability, short response time and high transmission accuracy.

[0043] In an exemplary embodiment of the present application, the electromagnetic induction heating system further includes a DC switching power supply 106 , which is connected between the high-frequency induction heating machine 102 and the USB data acquisition card 5 .

[0044] In this embodiment, the DC power switch is controlled by programming software, thereby controlling the power of the high-frequency induction heater 102 and the temperature of the heating platform 101 .

[0045] In an exemplary embodiment of the present application, the liquid nitrogen cooling system 2 includes a first control module 201, a first power switch 202, a liquid nitrogen tank 203, a spray head 204 and a liquid nitrogen pipeline 205. The first control module 201 is electrically connected to the USB data acquisition card 5, the first power switch 202 is electrically connected to the first control module 201, the liquid nitrogen tank 203 is electrically connected to the first power switch 202, the liquid nitrogen pipeline 205 is connected to the liquid nitrogen tank 203, and the spray head 204 is connected to the liquid nitrogen pipeline 205.

[0046] In this embodiment, the liquid nitrogen tank is used to store liquid nitrogen, and the liquid nitrogen pipeline 205 is used to connect the spray head 204 and the liquid nitrogen tank 203. The liquid nitrogen in the liquid nitrogen tank is transported to the spray head 204 through the liquid nitrogen pipeline 205. The spray head 204 is located above the heating platform 101, and the liquid nitrogen is sprayed on the solder joint through the spray head 204, so as to achieve the cooling effect on the solder joint; the spray head 204 includes but is not limited to the use of a porous nozzle, a rotary nozzle, etc., which can make the liquid nitrogen cover a larger area, accelerate the evaporation rate, and thus enhance the cooling effect. The first control module 201 is connected to the output end of the USB data acquisition card 5. When it is detected that the temperature of the solder joint rises to the preset heating temperature, the programming software feeds back the calculated temperature signal to the USB data acquisition card 5, and the USB data acquisition card 5 transmits the signal to the first control module 201. The first control module 201 controls the first power switch 202 to turn on, thereby controlling the liquid nitrogen to spray out, and achieving the cooling of the solder joint.

[0047] In an exemplary embodiment of the present application, a pressure regulator 206 is provided on the liquid nitrogen tank 203, and the pressure regulator 206 is used to adjust the spraying pressure of the liquid nitrogen in the liquid nitrogen tank 203 to adjust the spraying rate of the liquid nitrogen.

[0048] In this embodiment, the spraying pressure of the liquid nitrogen tank 203 is adjusted by the pressure regulator 206, so as to control the liquid nitrogen to be sprayed uniformly at a certain rate.

[0049] In an exemplary embodiment of the present application, the dry ice cooling system 3 includes a second control module 301, a second power switch 302, an air compressor 303, a dry ice cabinet 304, a dry ice pipe 305 and a spray gun 306. The second control module 301 is electrically connected to the USB data acquisition card 5, the second power switch 302 is electrically connected to the second control module 301, the air compressor 303 is electrically connected to the second power switch 302, the dry ice cabinet 304 is connected to the air compressor 303, the dry ice pipe 305 is connected to the dry ice cabinet 304, and the spray gun 306 is connected to the dry ice pipe 305.

[0050] In this embodiment, the dry ice cabinet 304 is used to store dry ice, which has a large volume and good thermal insulation performance; the air compressor 303 is used to provide the pressure required for the dry ice to be sprayed, and the dry ice is transmitted to the spray gun 306 through the dry ice pipeline 305. The spray gun 306 is located above the heating platform 101, and the dry ice particles are sprayed on the weld point through the spray gun 306. When the dry ice is sprayed, the dry ice particles sprayed at a high speed hit the surface of the weld point, generating a strong physical impact force. At the same time, the dry ice quickly sublimates from a solid state to a gaseous state during the impact process, absorbing a large amount of heat, causing the local temperature of the weld point surface to drop sharply. This temperature change and the physical impact force work together to help break the oxide film on the surface of the weld point and peel it off from the surface; and due to the electromagnetic induction heating and dry ice cooling, the heating time and cooling time of the weld point are both short. During the thermal cycle, the oxide film has no time to form, which can effectively ensure that the dry ice cooling system 3 intervenes in the cooling experiment process, and can exclude the situation where the oxide film cracks cause the weld point cracks. The second control module 301 is connected to the output end of the USB data acquisition card 5. After the second control module 301 acquires the signal from the USB data card, the second power switch 302 is turned on, and the air compressor 303 starts to operate, so that dry ice is sprayed out with the spray gun 306, thereby achieving a cooling effect on the welding point.

[0051] In an exemplary embodiment of the present application, an air filter 307 is provided between the air compressor 303 and the dry ice cabinet 304 , and the air filter 307 is used to filter impurities in the air input into the dry ice cabinet 304 by the air compressor 303 .

[0052] In this embodiment, by arranging an air filter 307 between the dry ice cabinet 304 and the air compressor 303 , moisture and impurities in the air can be effectively filtered, thereby preventing moisture or impurities in the air from entering the dry ice cooling system 3 .

[0053] In an exemplary embodiment of the present application, the high-speed camera system includes a high-speed camera 4 and control shooting software. The high-speed camera 4 is used to shoot solder joints and solder samples. The control shooting software is installed on a terminal computer 6. The control shooting software is used to control the shooting parameters of the high-speed camera 4 and to display and save the captured images in real time.

[0054] In this embodiment, a high-speed camera system is set up to monitor and record the surface state changes of the solder joint and the cracking path of the crack in real time, and the captured images can be processed. The experimenter can view the images directly on the terminal computer 6, so that the experimenter can clearly observe the early stages and microscopic processes of crack generation.

[0055] See also Figure 3 The embodiment of the present application also proposes an experimental method for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue.

[0056] In an exemplary embodiment of the present application, an experimental method for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue includes at least steps S110 to S160.

[0057] In step S110 , the solder joint and the solder sample are fixed on the heating stage 101 .

[0058] Exemplarily, the solder joint and the solder sample are brought into direct contact with the heating platform 101 and fixed. The purpose of direct contact is that the high-frequency magnetic field generated by the electromagnetic heating system 1 causes eddy currents to be generated inside the metal heating platform 101 to achieve heating, and solid-solid heat exchange is performed between the heating platform 101 and the solder joint to heat the solder joint. The purpose of fixing is that the liquid nitrogen cooling system 2 or the dry ice spray system will cause impact on the solder joint on the heating platform 101 when cooling it. By fixing it to the heating platform 101, the solder joint is prevented from being detached from the heating platform 101.

[0059] In step S120, the preset heating temperature and the preset cooling temperature, the preset heating time and the heating and heat preservation time, the preset cooling time and the cooling and heat preservation time are set on the programming software of the terminal computer 6, and the cooling system is selected on the terminal computer 6.

[0060] Exemplarily, the preset heating temperature is 120°C, the preset cooling temperature is -20°C, the preset heating time is 10 seconds, the heating and heat preservation time is 10 seconds, the preset cooling time is 10 seconds, and the cooling and heat preservation time is 10 seconds; by heating the solder joint to the preset heating temperature and then cooling it to the preset cooling temperature, the cycle is continuously repeated until cracks appear in the solder joint and the solder sample, thereby completing a thermal fatigue experiment; the experimenter can select the cooling system on the terminal computer 6.

[0061] In step S130, the electromagnetic heating system 1 heats the solder joint and the solder sample for a preset heating time, so that the solder joint and the solder sample reach a preset heating temperature, and maintains the current temperature and the heating and heat preservation time.

[0062] Exemplarily, by heating the solder joint and the solder sample through the electromagnetic heating system 1, the solder joint can be heated to a preset temperature in a relatively short time, and the heating and heat preservation time can be maintained so that the solder joint is heated evenly.

[0063] In step S140, if the dry ice cooling system 3 is selected, the terminal computer 6 controls the electromagnetic heating system 1 to turn off and turns on the dry ice cooling system 3. The dry ice cooling system 3 cools the solder joints and solder samples for a preset cooling time, so that the solder joints and solder samples reach a preset cooling temperature, maintain the current temperature and maintain the cooling and insulation time.

[0064] Exemplarily, the dry ice cooling system 3 can effectively remove the oxide film on the surface of the solder joint, avoid the influence of the cracking of the oxide film on the solder joint, and thus accurately judge the thermal fatigue performance of the solder joint; maintain the cooling and heat preservation time to make the solder joint cool evenly.

[0065] In step S150, if the liquid nitrogen cooling system 2 is selected, the terminal computer 6 controls the electromagnetic heating system 1 to turn off and turns on the liquid nitrogen cooling system 2. The liquid nitrogen cooling system 2 cools the solder joints and solder samples for a preset cooling time, so that the solder joints and solder samples reach a preset cooling temperature, maintain the current temperature and maintain the cooling and insulation time.

[0066] Exemplarily, the solder joint is cooled by the liquid nitrogen cooling system 2 to ensure that the cooling temperature of the solder joint is consistent. The liquid nitrogen cooling system 2 retains the influence of the oxide film on the solder joint. According to the form of crack generation, it can be effectively determined whether the solder joint crack is caused by cracks generated inside the solder joint or by cracks caused by cracks in the oxide film.

[0067] In step S160, the state changes of the solder joint and the solder are photographed and captured by a high-speed camera system.

[0068] For example, by setting up a high-speed camera system to monitor and record the surface state changes of the weld and the cracking path of the crack in real time, and being able to process the captured images, the experimenter can view the images directly on the terminal computer 6, so that the experimenter can clearly observe the early stages and microscopic processes of crack generation.

[0069] Working principle: the present application heats the solder joint and the solder sample through the electromagnetic heating system 1, and cools the solder joint and the solder sample through the liquid nitrogen cooling system 2 or the dry ice cooling system 3, and can complete a thermal cycle in a shorter time. Compared with the traditional thermal cycle, the experimental efficiency is greatly improved; the high-speed camera system can observe and record the solder joint state and the cracking path of the crack in real time, and clearly observe the crack generation process; by adopting the dry ice cooling system 3 to cool the solder joint, the dry ice can effectively remove the oxide film on the surface of the solder joint, thereby eliminating the influence of the cracking of the oxide film on the solder joint cracking; by cooling the solder joint through the liquid nitrogen cooling system 2, under the condition that the heating temperature and the cooling temperature are unchanged, it can be effectively determined according to the crack generation form whether the solder joint cracking is caused by cracks inside the solder joint or by cracks caused by the cracking of the oxide film.

[0070] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An experimental device for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue, characterized in that: include: Electromagnetic heating system for heating solder joints and solder samples; A liquid nitrogen cooling system, used to cool the solder joints and solder samples; A dry ice cooling system, used to remove oxide films on the surfaces of the solder joints and solder samples and to cool the solder joints and solder samples; A high-speed camera system, used to photograph and record the state changes of the solder joints and solder samples; A USB data acquisition card, the electromagnetic induction heating system, the liquid nitrogen cooling system and the dry ice cooling system are all connected to the USB data acquisition card; The terminal computer, the USB data acquisition card and the high-speed camera system are connected to the terminal computer, and the terminal computer is provided with programming software.

2. The experimental device for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue according to claim 1, characterized in that: The electromagnetic heating system comprises a heating platform, a high-frequency induction heating machine and an induction coil. The induction coil is arranged around the heating platform. The high-frequency induction heating machine is connected to the induction coil. The heating platform is used to carry the solder joint and the solder sample.

3. The experimental device for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue according to claim 2, characterized in that: The electromagnetic induction heating system also includes a temperature detection element, which is used to detect the temperature of the solder joints and solder samples on the heating table. An intelligent temperature transmitter is provided between the temperature detection element and the USB data acquisition card, and the intelligent temperature transmitter is used to amplify the temperature signal of the temperature detection element.

4. The experimental device for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue according to claim 3, characterized in that: The electromagnetic induction heating system also includes a DC switching power supply, which is connected between the high-frequency induction heating machine and the USB data acquisition card.

5. The experimental device for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue according to claim 1, characterized in that: The liquid nitrogen cooling system includes a first control module, a first power switch, a liquid nitrogen tank, a spray head and a liquid nitrogen pipeline, the first control module is electrically connected to the USB data acquisition card, the first power switch is electrically connected to the first control module, the liquid nitrogen tank is electrically connected to the first power switch, the liquid nitrogen pipeline is connected to the liquid nitrogen tank, and the spray head is connected to the liquid nitrogen pipeline.

6. The experimental device for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue according to claim 5, characterized in that: The liquid nitrogen tank is provided with a pressure regulator, and the pressure regulator is used to adjust the spraying pressure of the liquid nitrogen in the liquid nitrogen tank to adjust the spraying rate of the liquid nitrogen.

7. The experimental device for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue according to claim 1, characterized in that: The dry ice cooling system includes a second control module, a second power switch, an air compressor, a dry ice cabinet, a dry ice pipe and a spray gun, the second control module is electrically connected to the USB data acquisition card, the second power switch is electrically connected to the second control module, the air compressor is electrically connected to the second power switch, the dry ice cabinet is connected to the air compressor, the dry ice pipe is connected to the dry ice cabinet, and the spray gun is connected to the dry ice pipe.

8. The experimental device for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue according to claim 7, characterized in that: An air filter is provided between the air compressor and the dry ice cabinet, and the air filter is used to filter impurities in the air input into the dry ice cabinet by the air compressor.

9. The experimental device for studying the mechanism of solder joint and solder crack generation under rapid thermal fatigue according to claim 1, characterized in that: The high-speed camera system includes a high-speed camera and control shooting software. The high-speed camera is used to shoot the solder joints and solder samples. The control shooting software is installed on the terminal computer. The control shooting software is used to control the shooting parameters of the high-speed camera and display and save the captured images in real time.

10. An experimental method for studying the mechanism of solder joints and solder cracks under rapid thermal fatigue, applied to the experimental device for studying the mechanism of solder joints and solder cracks under rapid thermal fatigue as claimed in any one of claims 1 to 9, characterized in that: The experimental method includes: Fix the solder joint and solder sample on a heating table; Set the preset heating temperature and preset cooling temperature, preset heating time and heating and heat preservation time, preset cooling time and cooling and heat preservation time on the programming software of the terminal computer, and select the cooling system on the terminal computer; The electromagnetic heating system heats the solder joint and the solder sample for a preset heating time, so that the solder joint and the solder sample reach a preset heating temperature, and maintains the current temperature and the heating and heat preservation time; If the dry ice cooling system is selected, the terminal computer controls the electromagnetic heating system to be turned off and the dry ice cooling system to be turned on. The dry ice cooling system cools the solder joints and solder samples for a preset cooling time, so that the solder joints and solder samples reach the preset cooling temperature, and maintain the current temperature and the cooling and heat preservation time; If the liquid nitrogen cooling system is selected, the terminal computer controls the electromagnetic heating system to be turned off and the liquid nitrogen cooling system to be turned on. The liquid nitrogen cooling system cools the solder joints and solder samples for a preset cooling time, so that the solder joints and solder samples reach the preset cooling temperature, and maintain the current temperature and the cooling and holding time; The state changes of solder joints and solder are captured by a high-speed camera system.

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