Testing device and method for elastic body packaging stress under strong restricted constraint structure

Abstract

The application discloses a testing device and method for elastomer packaging stress under strong limited constraint structure, wherein the device is composed of a strong limited constraint device formed by a base and a constraint sleeve to inhibit free deformation of elastomer material; a cantilever beam structure is introduced into the device, the constraint degree of the device is adjusted by changing the thickness of the cantilever beam and the gap between the cantilever beam and the side edge, and in-situ strain measurement is performed by utilizing the characteristics of large span and easy deformation of the cantilever beam. The testing method deducts the influence of heat output to obtain mechanical strain data of the measuring point, and ensures the stress analysis accuracy. The strong limited constraint elastomer packaging stress testing device and method construct an approximate three-dimensional constraint structure necessary for elastomer to form observable stress, the elastomer filling is simple and easy to implement, the constraint degree of the structure is adjustable, and the device is suitable for various elastomer packaging applications.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electronic packaging, and particularly relates to a testing device and method for encapsulation stress of elastomer under strong restricted constraint structure. BACKGROUND

[0002] Elastomer materials such as silicone and polyurethane have the characteristics of low crosslinking density, easy disassembly and repair, and low hardness, and are widely used in the insulation coating, encapsulation and potting of electronic components and circuit boards. The electronic packaging industry generally believes that the modulus of elastomer materials is low, and the encapsulation stress of elastomer materials is often ignored in packaging design. However, in elastomer electronic packaging, there are also problems such as cracking of elastomer, interface delamination or fracture of stress-sensitive materials (such as magnetic cores and silicon wafers) caused by encapsulation stress, and these problems are increasingly prominent with the development of integrated and high-power electronic products. Therefore, the development of encapsulation stress testing devices and methods suitable for elastomer packaging materials has important value for the analysis and control of elastomer encapsulation stress and the improvement of the reliability of related electronic products.

[0003] The stress failure of elastomer encapsulation usually occurs in the approximately three-dimensional constraint structure formed by the specific materials and structure of electronic products, and is usually caused by high-temperature or low-temperature loading. The applicant has carried out research on the thermal properties of elastomer packaging materials, and the results show that the elastomer packaging materials have the characteristics of approximately incompressible elastic mechanics parameters and high thermal expansion coefficient. Influenced by the incompressible characteristics and Poisson's ratio close to 0.5, the Young's modulus of the elastomer packaging material is usually in the order of MPa, and the bulk modulus is in the order of GPa. Based on the derivation of the theory of elasticity, it is known that the encapsulation stress in one-dimensional and two-dimensional constraint structures is determined by the Young's modulus, and the encapsulation stress in three-dimensional constraint structure is determined by the bulk modulus. Under the conditions of curing shrinkage and temperature change, the encapsulation stress of elastomer packaging materials under one-dimensional and two-dimensional constraints is low, while the encapsulation stress level under three-dimensional constraint is higher and can approach the encapsulation stress level of hard polymer. Therefore, the analysis of elastomer encapsulation stress focuses on the encapsulation stress in the strong restricted constraint structure of approximately three-dimensional constraint, and only in the strong restricted constraint structure can the elastomer produce significant encapsulation stress that may cause failure.

[0004] The existing encapsulation stress test method is mainly aimed at hard polymer encapsulation, and is difficult to be applied to elastomer encapsulation material. The main problem is that the existing encapsulation stress test device generally does not consider the structural constraint in the configuration design, and the structural constraint degree is generally low. The Young's modulus of the encapsulation stress on the encapsulation material is much greater than the bulk modulus, and the formation and evolution law of the stress of the elastomer material under strong constraint cannot be reflected. The three-dimensional constraint structure form of the closed metal ball or the pipe with extremely high length-diameter ratio is proposed in the hard polymer stress mechanism research literature, but the constraint degree is difficult to adjust, the test implementation is difficult, and the feasibility of the elastomer encapsulation stress test is not verified.

[0005] Therefore, it is necessary to develop a strong constraint structure encapsulation stress test device suitable for elastomer material, so as to realize the accurate evaluation and analysis of the elastomer encapsulation stress of high-integration electronic products. SUMMARY

[0006] Therefore, the present application provides a strong constraint structure encapsulation stress test device and method for elastomer.

[0007] To achieve this purpose, the first aspect of the present application provides a strong constraint structure encapsulation stress test device for elastomer. The device comprises a base and a constraint sleeve (including a side wall and a cantilever beam) to form a strong constraint structure cavity filled with elastomer. The constraint degree can be adjusted by adjusting the thickness and gap distance of the cantilever beam structure. Based on the relationship between mechanical strain and stress, the measurement of the encapsulation stress of the elastomer is realized by attaching a sensor to the cantilever beam structure to monitor the mechanical strain.

[0008] The test device comprises a base, a constraint sleeve, a strain sensor and a temperature sensor.

[0009] The base is connected to the bottom of the constraint sleeve by screwing.

[0010] The constraint sleeve is a hollow structure with a cantilever beam inside. The cantilever beam is integrally formed with the side wall of the constraint sleeve. A gap is provided between the pair of symmetrical sides of the cantilever beam and the side wall of the constraint sleeve.

[0011] The strain sensor and the temperature sensor are arranged in pairs on the upper and lower surfaces of the cantilever beam, and are located at the midpoint position of the cantilever beam span.

[0012] Preferably, the temperature sensor is any one of a fiber Bragg grating sensor.

[0013] Preferably, the strain sensor is any one of a strain gauge, a strain rosette and a fiber Bragg grating sensor.

[0014] Preferably, the temperature sensor is fixed by polyimide tape. The strain sensor is fixed by glue.

[0015] Preferably, the gap between the cantilever beam side and the constraint sleeve side wall is 1mm to 3mm.

[0016] Preferably, the cantilever beam thickness is adjusted according to actual conditions, and the thickness is designed to ensure that the deformation of the cantilever beam during the curing of the elastomer packaging material can be measured and the cantilever beam does not plastically deform.

[0017] Preferably, the height of the elastomer packaging material is above the upper surface of the cantilever beam when the test device is in use.

[0018] The second aspect of the application provides a test method for the stress of an elastomer packaging under a strong constraint structure, which is based on the test device described above, and the method includes testing the residual stress of the elastomer packaging material during curing and testing the thermal stress of the elastomer packaging material during packaging.

[0019] (1) The test of the residual stress of the elastomer packaging material during curing is as follows:

[0020] S1-1: Paste strain sensors and temperature sensors on the upper and lower surfaces of the cantilever beam of the constraint sleeve, and assemble with the base to form a constraint cavity;

[0021] S1-2: Place the constraint cavity in an environmental test chamber, and zero the strain sensors at room temperature T0; start the temperature control of the environmental test chamber, first cool down and then warm up, and collect the strain ε i (t i,rsc ) and temperature data T i (t i ) of the cantilever beam at different times t i ) during the whole process; use the strain ε i,rsc (t i ) and temperature data T i (t i ) to fit the functional relationship ε i,rsc (T i ) between the strain ε i (t i ) of the cantilever beam and the temperature T i,rsc (t i ), and draw a thermal output temperature curve with T i (t i ) as the horizontal coordinate and ε i,rsc (t i ) as the vertical coordinate.

[0022] S1-3: According to the process requirements, mix the ingredients of the elastomer packaging material uniformly, place it in a vacuum environment for bubble removal treatment, and then inject it into the metal cavity formed by the base and the constraint sleeve;

[0023] S1-4: Start the temperature control of the environmental test chamber, carry out the curing process of the elastomer packaging material, and collect the indicated strain j and temperature data of the cantilever beam at different time t during the curing process of the elastomer packaging material

[0024] S1-5: Obtain the strain of the cantilever beam at different temperature data from the heat output temperature curve obtained in S1-2 by using interpolation method

[0025] S1-6: Calculate the curing residual stress of the elastomer packaging material:

[0026] (II) The test of the packaging thermal stress of the elastomer packaging material is as follows:

[0027] First, obtain the heat output temperature curve and fill the elastomer packaging material to be tested, and the operation steps are the same as S1-1-S1-3 in the test of the curing residual stress of the elastomer packaging material

[0028] Next, set the high-low temperature cycle condition, start the temperature control of the environmental test chamber, carry out the temperature cycle loading of the elastomer packaging material, and collect the indicated strain j and temperature data of the cantilever beam at different time t during the high-low temperature cycle test of the elastomer packaging material to be tested

[0029] Then, obtain the strain of the cantilever beam at different temperature data from the heat output temperature curve obtained in S1-2 by using interpolation method

[0030] Finally, calculate the packaging thermal stress of the elastomer to be tested:

[0031] Preferably, S1-2 further includes eliminating the zero drift of the strain sensor when it is first subjected to high and low temperatures, and specifically includes:

[0032] First, set multiple temperature rising and falling cycles, and collect the strain data and temperature data during the temperature rising and falling process, and record the starting time and ending time of the last temperature rising cycle as t k and t l ;

[0033] Next, after the temperature rising and falling cycle is completed, the temperature is restored to room temperature T0 and is kept, and the ending time of the keeping is recorded as t n ;

[0034] Then, use the time period t k ~ tl The strain ε collected inside i,rsc (t i ) and temperature data T i (t i ) to calculate the function relationship between strain ε i,rsc (t i ) and temperature T i (t i ) ε i,rsc (T i );

[0035] Finally, the strain at the end of the heat preservation time t n is taken as the strain zero point ε n,rsc (t n ), and the function relationship ε i,rsc (T i ) is corrected to obtain the function relationship between the corrected strain ε i,rsc (t i ) and temperature T i (t i ): ε i ′ ,rsc (T i ) = ε i,rsc (T i ) - ε n,rsc (t n ), and the heat output temperature curve drawn according to the corrected function relationship.

[0036] The beneficial effects of the present application are: the test device and method for packaging stress of elastomer under strong limited constraint structure disclosed by the present application: (1) the device designed has the structural characteristics of strong limited constraint: the device adopts a base and a constraint sleeve (including a side wall and a cantilever beam) to form a cavity filled with elastomer material, after the cavity is filled with elastomer material, the base, cantilever beam and constraint sleeve of the cavity will inhibit the deformation of the elastomer material, thereby forming strong limited constraint; by adjusting the thickness of the cantilever beam and the gap between the cantilever beam and the side, the degree of constraint can be adjusted; the cantilever beam and the side are provided with a gap space, which facilitates the filling of the elastomer, and only the free deformation in the height direction within the gap has little effect on the strong limited constraint structure of the overall test device. (2) By using the above device, the strain of the elastomer packaging material can be measured during the solidification shrinkage process and under high and low temperature environmental conditions, the deformation of the elastomer packaging material during the solidification process and the thermal expansion and contraction deformation under high and low temperature environments are reflected on the cantilever beam, and the measurement of the solidification residual stress and thermal stress of the elastomer packaging material is realized. The device can not only test the solidification residual stress during the solidification process, but also test the thermal stress caused by temperature change, so that the solidification residual stress and thermal stress are decoupled.

[0037] The test device and method provided in the patent have the following uses: (1) material selection comparison of elastomer packaging materials, the method can obtain quantitative analysis results of packaging stress and stress cracking and delamination risk of different elastomer packaging materials under strong constraint structure, for guiding material selection design; (2) for guiding elastomer packaging structure optimization design, the method can evaluate the failure risk of elastomer packaging materials under different degrees of strong constraint structure, thereby guiding the reverse design of packaging structure; (3) for elastomer packaging stress mechanism analysis, the method can obtain process data of curing residual stress and thermal stress formation, thereby obtaining stress formation and evolution mechanism; (4) for elastomer packaging stress simulation model checking, the method can quantitatively obtain packaging stress time-varying data of elastomer materials under curing forming and high temperature and low temperature conditions, which can provide reference data for simulation model and verify simulation model accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 It is a structural schematic view of the test device for elastomer packaging stress under strong constraint structure in the embodiment of the application.

[0039] Figure 2 It is a top view of the test device for elastomer packaging stress under strong constraint structure in the embodiment of the application (including elastomer packaging material).

[0040] Figure 3 It is an A-A cross-sectional view of Figure 2

[0041] Figure 4 It is a top view of the test device for elastomer packaging stress under strong constraint structure in the embodiment of the application (hidden elastomer packaging material)

[0042] Figure 5 It is an A-A cross-sectional view of Figure 4

[0043] Wherein: 1, base; 2, constraint sleeve; 3, elastomer packaging material; 4, strain sensor; 5, temperature sensor. DETAILED DESCRIPTION

[0044] Those skilled in the art will appreciate that the embodiments described herein are presented to assist the reader in understanding the principles of the application and should be understood as not limiting the scope of protection of the application to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations according to the technical inspiration disclosed in the application without departing from the essence of the application, and these modifications and combinations are still within the scope of protection of the application.

[0045] ​​The application will be described in detail below with reference to the drawings and specific embodiments.

[0046] Referring to Figures 1-5 In the test device for the stress of the elastomer package under strong and limited constraint structure, the test device comprises a base 1 and a constraint sleeve 2.

[0047] The base 1 is threadedly connected to the bottom of the constraint sleeve 2, the constraint sleeve 2 is a hollow structure with a cantilever beam arranged inside, a gap is arranged between the side edge of the cantilever beam and the side wall of the constraint sleeve 2, so that the elastomer package material can be effectively poured into the area below the cantilever beam; the cantilever beam is integrally formed with the side wall of the constraint sleeve, and during the temperature test, the cantilever beam and the side wall are rigidly connected and cannot slide relative to each other, and the two are fixedly connected to assemble a constraint cavity, which provides external constraint for the elastomer material and suppresses the thermal expansion and contraction deformation of the elastomer material.

[0048] The strain sensor 4 and the temperature sensor 5 are arranged in pairs on the upper and lower surfaces of the cantilever beam and are located at the midpoint position of the span of the cantilever beam, for measuring the solidification residual stress and thermal stress of the elastomer package material to be tested. The double-end fixed cantilever beam structure is symmetrical, the strain on the upper and lower surfaces of the cantilever beam changes little in the length direction of the cantilever beam at the span center position, the position dependence of the strain sensor is low, and the error caused by the deviation of the pasting position is small.

[0049] As an embodiment, the temperature sensor 5 is preferably a thermocouple, and other high-sensitivity temperature sensors can also be used instead; the strain sensor 4 is any one of a strain gauge, a strain rosette and a fiber Bragg grating sensor, and if a strain gauge and a fiber Bragg grating sensor are selected, there can be one or more.

[0050] As an embodiment, the temperature sensor 5 is fixed by being pasted with a high-temperature-resistant adhesive tape, and polyimide is preferred; the strain sensor 4 is fixed by being pasted with high-temperature-resistant glue.

[0051] A certain gap is reserved between the side edge of the cantilever beam and the constraint sleeve, and the degree of constraint of the elastomer material is adjusted by the size of the gap; in order to achieve strong and limited constraint, the width of the gap between the side edge of the cantilever beam and the inner surface of the constraint sleeve is 1mm-3mm.

[0052] The thickness of the cantilever beam is adjusted according to the actual situation, and the thickness is designed to ensure that the deformation of the cantilever beam during the curing process of the elastomer package material can be measured and the cantilever beam does not plastically deform. If it is found in the test that the strain is too small, the wall thickness is appropriately reduced or increased to reduce the rigidity of the cantilever beam, so as to ensure that the deformation of the cantilever beam during the curing process and the temperature change process reaches the measurable order of magnitude of the strain gauge, otherwise, the thickness of the cantilever beam can be appropriately increased to reduce the risk of plastic deformation of the metal cantilever beam.

[0053] When the above-mentioned testing device is used, the filling height of the elastomer encapsulation material 3 is higher than that of the cantilever beam to ensure a strong transfer between the elastomer encapsulation material and the cantilever beam.

[0054] The principle of the aforementioned stress testing device for elastomeric encapsulation under strongly constrained structures is as follows: Utilizing the chemical shrinkage deformation characteristics of the elastomeric encapsulation material during curing and the mismatch in thermal expansion coefficients between the elastomeric and metallic materials, combined with the characteristics of cantilever beams—large span, low stiffness, and easy deformation—a structure is designed to measure the mechanical stress generated by the expansion and deformation of the elastomeric encapsulation material. During the curing process and at low temperatures, the elastomeric material undergoes chemical and thermal shrinkage, respectively. The thermal expansion coefficient of the elastomeric material is much greater than that of the metallic material. During curing shrinkage and cooling, the elastomeric material contracts inward, generating compressive strain on the upper surface and tensile strain on the lower surface of the cantilever beam. During heating, the elastomeric material expands outward, generating tensile strain on the upper surface and compressive strain on the lower surface of the cantilever beam.

[0055] The device designed in this invention has a small free surface area for the elastomeric encapsulation material, allowing it to deform freely only along its height within the gap between the cantilever beam and the side. Therefore, the overall design structure exhibits a strongly constrained form. The degree of constraint can be adjusted by modifying the thickness of the cantilever beam and the gap between the cantilever beam and the side. This strongly constrained structure enables measurable strain of the elastomeric encapsulation material during curing shrinkage and under high and low temperature conditions. Through this design, the deformation of the elastomeric encapsulation material during curing and the thermal expansion and contraction under high and low temperature conditions are reflected on the cantilever beam, enabling the measurement of residual stress and thermally induced stress in the cured elastomeric encapsulation material.

[0056] Based on the above testing device, a testing method for the encapsulation stress of an elastomer under a constrained structure is proposed. This method includes testing the residual stress of the curing of the elastomer encapsulation material and testing the thermal stress caused by the encapsulation of the elastomer encapsulation material.

[0057] (a) The test results for residual stress after curing of elastomeric encapsulation materials are as follows:

[0058] S1-1: Strain sensors and temperature sensors are attached to the upper and lower surfaces of the cantilever beam of the constraint sleeve and assembled with the base to form a constraint cavity;

[0059] S1-2: Place the constraint chamber in the environmental test chamber and zero the strain sensor at room temperature T0; start the environmental test chamber temperature control, first cooling and then heating. Throughout the process, use strain and temperature sensors to collect data on the cantilever beam at different times t. i strain ε i,rsc (t i ) and temperature data T i (ti ); the strain ε i,rsc (t i ) and temperature data T i (t i ) are fitted to obtain a function relationship ε i,rsc (T i ) between the strain ε i (t i ) of the cantilever beam and the temperature T i,rsc (t i ), and a thermal output temperature curve is drawn with T i (t i ) as the horizontal coordinate and ε i,rsc (t i ) as the vertical coordinate.

[0060] S1-3: According to the process requirements, the ingredients of the elastomer packaging material are uniformly mixed, then placed in a vacuum environment for bubble removal treatment, and then injected into the metal cavity formed by the base and the constraint sleeve;

[0061] S1-4: Start the temperature control of the environmental test chamber, perform the curing process of the elastomer packaging material, and collect the indicated strain j and temperature data of the cantilever beam at different times t

[0062] S1-5: Using interpolation method, the strain of the cantilever beam at different temperature data is obtained from the thermal output temperature curve obtained in S1-2.

[0063] S1-6: Calculate the curing residual stress of the elastomer packaging material:

[0064] (II) Test of the packaging thermal stress of the elastomer packaging material as follows:

[0065] First, obtain the thermal output temperature curve and fill the elastomer packaging material to be tested, and the operation steps are the same as S1-1-S1-3 in the test of the curing residual stress of the elastomer packaging material.

[0066] Next, set the high-low temperature cycle conditions, start the temperature control of the environmental test chamber, perform the temperature cycle loading of the elastomer packaging material, and collect the indicated strain j and temperature data of the cantilever beam at different times t

[0067] Then, using interpolation method, the strain of the cantilever beam at different temperature data is obtained from the thermal output temperature curve obtained in S1-2. Strain of the cantilever beam

[0068] Finally, the thermally induced stress of the elastomer encapsulation under test is calculated:

[0069] As another embodiment, S1-2 above can also consider eliminating the zero-point drift of the strain sensor when it first experiences high and low temperatures, specifically including:

[0070] First, multiple heating and cooling cycles were set up, and strain and temperature data were collected during the heating and cooling processes. The start and end times of the last heating cycle were recorded as t1 and t2, respectively. k and t l ;

[0071] Next, after the heating and cooling cycle is completed, the temperature is restored to room temperature T0 and held at that temperature, with the end time of the holding period recorded as t. n ;

[0072] Then, using the time period t k ~t l Strain ε collected internally i,rsc (t i ) and temperature data T i (t i The strain ε was calculated. i,rsc (t i ) and temperature T i (t i The functional relationship between ε i,rsc (T i );

[0073] Finally, the end time of heat preservation is t. n The strain is taken as the zero strain point ε n,rsc (t n ), for the functional relation ε i,rsc (T i The strain ε is then corrected to obtain the corrected strain. i,rsc (t i ) and temperature T i (t i The functional relationship between ε and ε: i ′ ,rsc (T i )=ε i,rsc (T i )-ε n,rsc (t n The heat output temperature curve was plotted using the corrected functional relationship.

[0074] The method is designed according to the test principle of the strain sensor, and the influence of the thermal output of the strain sensor is considered. The indication strain of the strain sensor is related to the mechanical strain and temperature of the measuring point, wherein only the mechanical strain reflects the size of the residual stress and the thermal stress, and the strain after the indication strain is deducted from the temperature-related strain, i.e. the thermal output, is the mechanical strain. The above method considers the influence of the deduction of the thermal output, firstly, the strain sensor is pasted to the outer side of the metal sheet, and the thermal output data of the strain sheet is obtained through the experiment in the unpackaged state, and then the thermal output data is deducted from the indication strain of the strain sensor in the solidification process and the high and low temperature environment, so as to obtain the mechanical strain of the measuring point.

Claims

1. A testing device for the encapsulation stress of an elastomer under a strongly constrained structure, characterized in that, The testing device includes a base, a constraint sleeve, a strain sensor, and a temperature sensor; The base is threadedly connected to the bottom of the constraint sleeve; The constraint sleeve is a hollow structure with an internal cantilever beam. The cantilever beam and the side wall of the constraint sleeve are integrally formed, and a gap is provided between a pair of symmetrical sides of the cantilever beam and the side wall of the constraint sleeve. The strain sensor and temperature sensor are arranged in pairs on the upper and lower surfaces of the cantilever beam, and are located at the midpoint of the span of the cantilever beam. The device consists of a base and a constraint sleeve forming a strongly constrained cavity filled with an elastic body. The degree of constraint can be adjusted by adjusting the thickness and gap distance of the cantilever beam structure.

2. The testing device for the encapsulation stress of an elastomer under a strongly constrained structure according to claim 1, characterized in that, The temperature sensor can be either a thermocouple or a fiber Bragg grating sensor.

3. The testing device for the encapsulation stress of an elastomer under a strongly constrained structure according to claim 1, characterized in that, The strain sensor can be any one of a strain gauge, strain rosette, or fiber optic grating sensor.

4. The testing device for the encapsulation stress of an elastomer under a strongly constrained structure according to claim 1, characterized in that, The temperature sensor is fixed by adhesive tape or welding; the strain sensor is fixed by adhesive with high and low temperature resistant glue.

5. The testing device for the encapsulation stress of an elastomer under a strongly constrained structure according to claim 1, characterized in that, The width of the gap between the side of the cantilever beam and the side wall of the constraint sleeve is 1mm to 3mm.

6. The testing device for the encapsulation stress of an elastomer under a strongly constrained structure according to claim 1, characterized in that, The thickness of the cantilever beam is adjusted according to the actual situation. Its thickness design can ensure that the deformation of the cantilever beam can be measured during the curing process of the elastomer encapsulation material and that the cantilever beam does not undergo plastic deformation.

7. The testing device for the encapsulation stress of an elastomer under a strongly constrained structure according to claim 1, characterized in that, When the testing device is in use, the encapsulation height of the elastomeric encapsulation material does not exceed the upper surface of the cantilever beam.

8. A method for testing the encapsulation stress of an elastomer under a strongly constrained structure, characterized in that, The method is performed based on the testing apparatus of any one of claims 1 to 7, and the method includes testing the residual stress of the curing of the elastic encapsulation material and testing the thermal stress caused by the encapsulation of the elastomeric encapsulation material. I. The test results for residual stress after curing of elastomeric encapsulation materials are as follows: S1-1: Strain sensors and temperature sensors are attached to the upper and lower surfaces of the cantilever beam of the constraint sleeve and assembled with the base to form a constraint cavity; S1-2: Place the constraint cavity in the environmental test chamber and zero the strain sensor at room temperature; start the environmental test chamber temperature control, first cooling and then heating, and use strain and temperature sensors to collect data on the sidewall cylinder at different times throughout the process. t i Strain at time ɛ i,rsc ( t i ) and temperature data T i ( t i According to strain ɛ i,rsc ( t i ) and temperature T i ( t i The time synchronization relationship can be used to obtain the strain. ɛ i,rsc ( t i ) and temperature T i ( t i The curves between ) ɛ i,rsc ( T i ), i.e., the heat output temperature curve; S1-3: According to the process requirements, after the elastomer encapsulation material is mixed evenly, it is placed in a vacuum environment for degassing treatment, and then injected into the metal cavity formed by the base and the constraint sleeve. S1-4: Start the environmental test chamber temperature control to carry out the curing process of the elastomer encapsulation material, and collect data on the cantilever beam at different times during the curing process of the elastomer encapsulation material. t j Indicated strain and temperature data ; S1-5: Using interpolation, obtain different temperature data from the heat output temperature curve obtained in S1-2. Strain of the cantilever beam ; S1-6: Calculate the curing residual stress of the elastomeric encapsulation material: ; II. The following are the tests for the thermal stress induced by the encapsulation of elastomeric encapsulation materials: First, obtain the thermal output temperature curve and fill the elastomer encapsulation material to be tested. The operation steps are the same as those in S1-1 to S1-3 of the test of the curing residual stress of the elastomer encapsulation material. Next, high and low temperature cycling conditions were set, the environmental test chamber temperature control was activated, and temperature cycling loading was performed on the elastomer encapsulation material. Data were collected at different times during the high and low temperature cycling test of the cantilever beam containing the elastomer encapsulation material under test. t j Indicated strain and temperature data; Then, using interpolation, different temperature data are obtained from the heat output temperature curve obtained in S1-2. Strain of the cantilever beam ; Finally, the thermally induced stress of the elastomer encapsulation under test is calculated: .

9. The method for testing the encapsulation stress of an elastomer under a strongly constrained structure according to claim 8, characterized in that, S1-2 also includes eliminating zero-point drift caused by the strain sensor during its first exposure to high and low temperatures, specifically including: First, multiple heating and cooling cycles were set up, and strain and temperature data were collected during the heating and cooling processes. The start and end times of the last heating cycle were recorded as follows: t k and t l ; Next, after the heating and cooling cycle is completed, the temperature is restored to room temperature. T 0 and keep warm, and record the end time of the warming process as 0. t n ; Then, using time periods t k ~ t l Strain acquired internally ɛ i,rsc ( t i ) and temperature data T i ( t i The strain was calculated without correction. ɛ i,rsc ( t i ) and temperature T i ( t i Functional relationship between ) ɛ i,rsc ( T i ); Finally, the insulation process ends. t n The strain is taken as the zero strain point ɛ n,rsc ( t n ), for functional relations ɛi,rsc ( T i The strain is then corrected to obtain the corrected strain. ɛ′ i,rsc ( t i ) and temperature T i ( t i Functional relationship between ) The heat output temperature curve was plotted using the corrected functional relationship.

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