A thermal environment pull-off test method for electronic products

Abstract

A thermal environment deflection test method for electronic products is used in deflection testing of single units supporting space launch vehicles and missile weapon systems. This method is used to determine product design margins, identify weaknesses, and conduct quantitative deflection testing to improve product reliability. This invention is a reliability enhancement method based on quantitative deflection testing.

Description

Technical Field

[0001] The present invention relates to a thermal environment deflection test method for electronic products. This method is applicable to electronic products for space vehicles and missile weapon systems. It is used in deflection testing of individual components of these systems to determine product design margins, identify weaknesses, and conduct quantitative deflection testing to improve product reliability. This invention provides a reliability enhancement method based on quantitative deflection testing. Background Art

[0002] The pull-off test is a typical reliability enhancement method. During the product development process, conducting pull-off tests on electronic products can effectively expose design and process weaknesses through rigorous assessment, thereby improving product reliability.

[0003] For a long time, the reliability of electronic products has been calculated through statistical calculations of data collected in laboratories and the field. This method focuses more on failure results and cannot be associated with the product design process. The failure physics method, on the other hand, quantifies the relationship between product design parameters and failure time, which can directly guide the design process. Reliability enhancement testing is mainly based on the principles of failure physics and selects product-sensitive design parameters for testing. The Highly Accelerated Stress Life Test (HALT), proposed by American scientists, is a qualitative reliability enhancement test based on failure physics. Although it can help identify product weaknesses, it is often unable to quantitatively evaluate the product's design margin. Summary of the Invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the existing technology, provide a thermal environment pull-off test method for electronic products, and a reliability enhancement test method for calculating the pull-off level of electronic products based on a fault physical model, and perform high temperature and temperature cycle pull-off tests on the product thermal environment.

[0005] The technical solution of the present invention is: a thermal environment tensile test method for electronic products, comprising:

[0006] Determine the design characteristics of the test object as input for its quantitative pull-off test;

[0007] Determine the tensile test limit of the test object based on the design characteristics of the test object;

[0008] Determine the high-temperature deflection quantitative model and deflection grade, the temperature cycle deflection quantitative model and temperature cycle deflection grade;

[0009] Establish initial conditions for test subjects;

[0010] Adjust the cut-off level of the pull-out test;

[0011] Perform a tensile test according to the previous settings to obtain the tensile test results for subsequent analysis of the weak links of the test object.

[0012] Furthermore, the design characteristics of the test object include design plans, design requirement documents, circuit diagrams, functional block diagrams, functional flow charts, functional performance indicators, fault judgment criteria, detection and monitoring methods, working conditions and working environment, historical usage data of the test object, and also include reliability design analysis data of the test object and fault data during field use.

[0013] Furthermore, the tensile test limits of the test object include: technical specification limits, design limits, working limits and destruction limits.

[0014] Furthermore, the high temperature tensile strength quantitative model is

[0015] SS=1-exp(-0.0017(ΔT+0.6) 0.6 t)

[0016] Among them, SS is the tensile strength, which actually represents the impact of the corresponding environmental stress on electronic products; ΔT is the tensile range, ΔT=(T U -T0)℃;T U is the pulling temperature; T0 is the initial high temperature; t is the high temperature test holding time.

[0017] Furthermore, the tensile strength level includes four levels, namely, level 1: initial high temperature and corresponding time, level 2: tensile strength SS=2%, level 3: tensile strength SS=4%, level 4: tensile strength SS=6%.

[0018] Furthermore, the temperature cycle deflection quantitative model includes:

[0019] SS=0.1-0.1*exp{-0.0017(ΔT+0.6) 0.6 [ln(e+v)] 3 N}

[0020] Where SS is the tensile strength; ΔT is the tensile range, ΔT=(T U -T0)℃;T U is the biased temperature cycle range; T0 is the initial temperature cycle range; N is the number of cycles; e is the natural logarithm; v is the temperature change rate. When the heating and cooling rates are different, the average temperature change rate is taken; v = (|V1|+|V2|) / 2, V1 is the heating rate, and V2 is the cooling rate.

[0021] Furthermore, the temperature cycle tensile strength level includes four levels, namely, level 1: initial temperature cycle range, temperature change rate and corresponding number of cycles, level 2: tensile strength SS = 2%, level 3: tensile strength SS = 4%, level 4: tensile strength SS = 6%.

[0022] Furthermore, the method for formulating the initial conditions of the test subject is any of the following conditions:

[0023] First condition: select a certain model identification level condition as the initial condition;

[0024] Second condition: Envelope the identification-level conditions of the potential application model of the product according to certain principles, and use the conditions after enveloping as the initial conditions;

[0025] The third condition: select a certain model acceptance level condition as the initial condition;

[0026] The fourth condition: Envelope the acceptance level conditions of the potential application model of the product according to certain principles, and use the enveloped conditions as the initial conditions

[0027] Fifth condition: The most severe conditions experienced by the test object in its historical or expected use environment are used as the initial conditions;

[0028] Sixth condition: Use the conditions given in the general specifications or standards of the test object as the initial conditions.

[0029] Furthermore, the method for adjusting the cutoff level of the pull-out test is:

[0030] The stress level corresponding to the deflection cutoff level exceeds the product design limit or working limit;

[0031] When there is no need to improve the product reliability level by an order of magnitude or more, the stress level corresponding to the deflection cutoff level does not exceed its destruction limit;

[0032] When the product reliability level needs to be improved by an order of magnitude or more, the stress level corresponding to the deflection cutoff level exceeds its destruction limit.

[0033] On the basis of the above coordination, the specific tensile strength under each tensile strength level may fluctuate by ±0.5%;

[0034] The technical specification limit takes precedence as the initial test condition for the product, and its stress level is not used as the deflection cutoff level.

[0035] Furthermore, during the pull-off test, if a fault occurs, it is handled according to the following method:

[0036] When a fault is confirmed, stop the test, restore the temperature in the test chamber to normal atmospheric conditions, and then remove the test object;

[0037] For non-responsible faults, repair the test object and restore it to the state before the fault occurs before continuing the test;

[0038] For responsible faults, the test is suspended, the fault is corrected, the design or process improvement of the test object is implemented, and the test is resumed after the test object implements the corrective measures;

[0039] After the functional performance of the subjects has fully recovered, the test will continue.

[0040] The advantages of the present invention compared with the prior art are:

[0041] (1) The present invention provides a product reliability enhancement test method by establishing a mapping relationship between test limits, test conditions, and pull-off levels;

[0042] (2) The present invention establishes a high-temperature quantitative tensile stress model, which can realize the high-temperature tensile stress test in a quantitative manner;

[0043] (3) The present invention can realize the temperature cycle pull-off test in a quantitative manner by establishing a temperature cycle temperature quantitative pull-off model.

[0044] (4) The present invention has accumulated experience in tensile testing of multiple models and set four quantitative tensile levels, providing a quantitative characterization method for the design margin of single-machine products. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0046] In order to better understand the above technical solution, the technical solution of the present application is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical solution of the present application, rather than limitations on the technical solution of the present application. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other.

[0047] The following is a further detailed description of a thermal environment pull-off test method for electronic products provided by the embodiment of the present application in conjunction with the accompanying drawings. The specific implementation method may include (eg Figure 1 shown):

[0048] Step 1: Clarify the design characteristics of the experimental subjects.

[0049] The present invention mainly focuses on the quantitative pull-off test of stand-alone products. First, the design information of the stand-alone product and the usage information of similar products should be collected as the input of the quantitative pull-off test. This information includes the design scheme, design requirement documents, circuit diagrams, functional block diagrams, functional flow charts, functional performance indicators, fault judgment criteria, detection and monitoring methods, working conditions and working environment, historical usage data of this product and similar products, including reliability design analysis data, fault data during field use and other information related to the stand-alone product (i.e., the test object). Before carrying out the quantitative pull-off test, in order to more effectively find the weak links, the information collection should be as comprehensive and detailed as possible.

[0050] Step 2: Determine the pull-out test limit.

[0051] The tensile test limit of the test object should be determined based on the above-mentioned information collected and the overall needs. The tensile test limit is the general framework for formulating the tensile test level and is the cutoff condition for the gradual implementation of the tensile test.

[0052] (1) Technical specification limit: The stress limit specified by the user or the manufacturer, within which the product is expected to operate; (2) Design limit: The limit designed by the manufacturer when designing the product, taking into account the design margin. The difference between the technical specification limit and the design limit is called the design margin; (3) Working limit: If a product fails at a certain stress level (set as An), but can return to normal after being reduced to the previous stress level (set as An-1) or without applying the test stress, then An-1 is the working limit; (4) Destruction limit: If a product fails at a certain stress level (set as An), and cannot return to normal after being reduced to the previous stress level (set as An-1) or without applying the test stress, then An is the destruction limit.

[0053] Step 3: Determine the quantitative model of high temperature deflection.

[0054] Different stresses have different effects on the failure rate of electronic products. The tensile strength indicates the degree of deviation of the test object under a certain test condition during the tensile test. The greater the degree of deviation, the stricter the test conditions, and the greater the possibility of product failure, thus identifying the product's weak links. The tensile strength calculation formula for high temperature test conditions is as follows:

[0055] SS=1-exp(-0.0017(ΔT+0.6) 0.6 t) (1)

[0056] Where:

[0057] SS—tensile strength, which actually represents the impact of corresponding environmental stress on electronic products;

[0058] ΔT—pull deviation range, ΔT=(T U -T0)℃;

[0059] T U —Pull-off temperature;

[0060] T0—initial high temperature;

[0061] t—High temperature test holding time.

[0062] Alternatively, based on the actual product conditions, an appropriate high-temperature acceleration model, such as the Arrhenius model, can be selected to quantitatively calculate the degree of deflection of the test object. However, the coefficients of the model need to be adjusted to match different deflection levels.

[0063] Step 4: Determine the high temperature pull-off level.

[0064] The design parameters for the quantitative high-temperature deflection test should be selected based on the product's design characteristics: the high-temperature hold time and high-temperature temperature. Whenever possible, the more sensitive parameters of the product should be selected for deflection testing to ensure that the deflection strength meets the expected test objectives. This invention proposes four levels of deflection testing for aerospace electronic products, each corresponding to a deflection strength. Level 1: Initial high-temperature temperature and corresponding time; Level 2: Deflection strength SS = 2%; Level 3: Deflection strength SS = 4%; Level 4: Deflection strength SS = 6%.

[0065] Initial conditions should be reasonably formulated based on product design characteristics and usage requirements. See step 7. Level 2 to Level 4 pull-off conditions are further tightened based on Level 1.

[0066] When the tensile test is carried out, the test can be carried out step by step according to the degree of tensile deviation, or the test can be carried out directly across levels according to the desired degree of tensile deviation.

[0067] Step 5: Determine the quantitative model of temperature cycle deviation.

[0068] Same as the third step, the calculation formula for the tensile strength under the temperature cycling test conditions is as follows:

[0069] SS=0.1-0.1*exp{-0.0017(ΔT+0.6) 0.6 [ln(e+v)] 3 N} (2)

[0070] SS—tensile strength, which actually represents the impact of corresponding environmental stress on electronic products;

[0071] ΔT—pull deviation range, ΔT=(T U -T0)℃;

[0072] T U —Temperature cycle range (high temperature - low temperature);

[0073] T0—initial temperature cycle range (high temperature-low temperature);

[0074] N—number of cycles, it is recommended to take an integer;

[0075] e—base of natural logarithms, 2.718;

[0076] v—Temperature change rate (℃ / min). When the heating and cooling rates are different, take the average temperature change rate.

[0077] v = (|V1| + |V2|) / 2 (V1 - heating rate, V2 - cooling rate).

[0078] Alternatively, based on the actual product conditions, an applicable temperature cycle acceleration model, such as the Coffin-Manson model, can be selected to quantitatively calculate the degree of pull-out of the test object. However, the coefficients of the model need to be adjusted to match different pull-out levels.

[0079] Step 6: Determine the temperature cycling deviation level.

[0080] The high and low temperature difference, temperature change rate and number of cycles should be selected as the design parameters of the quantitative temperature cycle tensile test according to the design characteristics of the product. As far as possible, more sensitive parameters of the product should be selected for tensile testing to ensure that the tensile strength meets the expected test objectives. The present invention proposes that four levels of tensile tests can be carried out on aerospace electronic products. The tensile strength of each tensile level can be fine-tuned according to actual conditions. The tensile levels are the same as the high-temperature tensile levels. Level 1: initial temperature cycle range, temperature change rate and corresponding number of cycles, Level 2: tensile strength SS = 2%, Level 3: tensile strength SS = 4%, Level 4: tensile strength SS = 6%.

[0081] Initial conditions should be reasonably formulated based on product design characteristics and usage requirements. See step 7. Level 2 to Level 4 pull-off conditions are further tightened based on Level 1.

[0082] When the tensile test is carried out, the test can be carried out step by step according to the degree of tensile deviation, or the test can be carried out directly across levels according to the desired degree of tensile deviation.

[0083] Step 7: Establish initial conditions for the experimental subjects.

[0084] Initial high temperature conditions and initial temperature cycle conditions are collectively referred to as initial test conditions. The method for establishing the initial conditions of the test object is any of the following conditions:

[0085] First condition: select a certain model identification level condition as the initial condition;

[0086] Second condition: Envelope the identification-level conditions of the potential application model of the product according to certain principles, and use the conditions after enveloping as the initial conditions;

[0087] The third condition: select a certain model acceptance level condition as the initial condition;

[0088] The fourth condition: Envelope the acceptance level conditions of the potential application model of the product according to certain principles, and use the enveloped conditions as the initial conditions

[0089] Fifth condition: The most severe conditions experienced by the test object in its historical or expected use environment are used as the initial conditions;

[0090] Sixth condition: Use the conditions given in the general specifications or standards of the test object as the initial conditions.

[0091] Step 8: Adjust the pull-off cutoff level.

[0092] Due to different product improvement requirements, the deviation test can be completed at any deviation level from one to four. The deviation level at the end of the deviation test is the cutoff level. According to steps three to seven of the present invention, the deviation levels of the test objects can be obtained. The test magnitude of each deviation level is compared with the product estimated limit obtained in step two to determine the deviation cutoff level of the product. The specific coordination relationship is as follows:

[0093] (1) The technical specification limit can be used as the initial test condition of the product, and its stress level is generally not used as the tensile cutoff level;

[0094] (2) In order to find the weak links of the product and achieve design and process improvements, the stress level corresponding to the tensile cutoff level should at least exceed the product design limit or working limit;

[0095] (3) When there is no need to significantly improve the reliability level of the product, the stress level corresponding to the tensile cutoff level generally does not need to exceed its destruction limit;

[0096] (4) When the reliability level of the product needs to be greatly improved, the stress level corresponding to the tensile cutoff level can exceed its destruction limit.

[0097] (5) On the basis of the above coordination, the specific tensile strength under each tensile strength level may fluctuate by ±0.5%, that is, tensile strength level one is the initial test condition, the tensile strength range of tensile strength level two is (1.5%≤SS≤2.5%), the tensile strength range of tensile strength level three is (3.5%≤SS≤4.5%), and the tensile strength range of tensile strength level four is (5.5%≤SS≤6.5%).

[0098] Step 9: Troubleshooting and classification.

[0099] If a fault occurs during the pull-off test, it should be handled as follows:

[0100] (1) When a fault is confirmed, the test should be stopped immediately, the temperature in the test chamber should be restored to normal atmospheric conditions, and the test product should be removed;

[0101] (2) For non-responsible faults, it is allowed to repair the product and restore it to the state before the fault occurs before continuing the test; among them, non-responsible faults are other faults specified in GJB 899A except for responsible faults;

[0102] (3) For responsible failures, the test should be suspended, the failure should be thoroughly analyzed and corrected, the product design or process should be improved, and the test should be resumed after corrective measures are implemented on the tested product. Among them, responsible failures are independent failures of the tested product as specified in GJB899A and any subordinate failures caused by them;

[0103] (4) When it is impossible to complete the corrective measures for the tested product in a timely manner, in order to ensure the continuity of the test, the correction can be delayed and the faulty components can be temporarily replaced, but functional components that are not faulty should not be replaced arbitrarily;

[0104] (5) After the functional performance of the product is fully restored, it can be placed in the test facility for further testing. The effectiveness of the corrective measures can be verified in subsequent tests while the weak links of the product can be further discovered.

[0105] Step 10: Analysis and improvement of weak links.

[0106] After finding the weak links of the product through the tensile test, design improvements or process improvements should be made, and the improvements should be verified. At the same time, the impact on the improvement of product reliability should be analyzed. If necessary, the tensile test should be carried out again for further verification.

[0107] The solution provided in the embodiment of the present application specifically includes the following steps:

[0108] Step 1: Clarify the design characteristics of the experimental subjects.

[0109] A certain FW-type stand-alone device A, serving as the video imaging device for the measurement system, primarily performs functions such as onboard image acquisition and collection. Its design input documents are listed in the A stand-alone device design brief, and its expected operating environment conditions are listed in the model documents, including the mechanical test conditions and thermal environment conditions. A stand-alone device A has completed its prototype design, as shown in the design drawings, and has also produced several prototypes. The design characteristics of the A stand-alone device, as confirmed by the above documents, are as follows:

[0110] (1) Image characteristics: such as image resolution, imaging requirements, illumination, etc.;

[0111] (2) Antenna characteristics: antenna style, operating frequency band, standing wave, etc.;

[0112] (3) Data transmission characteristics: transmission rate, packet loss rate, etc.

[0113] (4) Other design features such as environmental adaptability.

[0114] Step 2: Determine the pull-out test limit.

[0115] The tensile test limit of the test object should be determined based on the above-mentioned information collected and the overall requirements.

[0116] (1) Technical specification limit: see the specific provisions in the technical conditions for acceptance of single-machine manufacturing A.

[0117] a) High temperature appraisal level: 60℃, 4h; acceptance level condition: 50℃, 4h;

[0118] b) Temperature cycle conditions: The identification level conditions are of the same order as the acceptance level conditions: -40℃~+60℃, the single cycle time is 4h, and there are 10 cycles in total.

[0119] (2) Design limit: The contractor takes into account a certain design margin when designing the product. The maximum junction temperature allowed by the device is above 125°C. After considering the temperature rise, the design limit is estimated to be 100°C;

[0120] (3) Working limit: Estimated working limit 75℃;

[0121] (4) Destruction limit: Estimated destruction limit is 110℃.

[0122] Step 3: Determine the quantitative model of high temperature deflection.

[0123] A preliminary calculation was performed based on the tensile strength calculation formula (1) under high temperature test conditions, see Table 1.

[0124] Table 1 Calculation of tensile strength under high temperature test conditions

[0125]

[0126] Step 4: Determine the high temperature pull-off level.

[0127] According to the design characteristics of the product, the high temperature holding time and high temperature can be used as the design parameters of the tensile test of the product.

[0128] A single machine pull-off level 1: initial high temperature and corresponding time, pull-off level 2: pull-off strength SS = 2%, pull-off level 3: strength SS = 4%, pull-off level 4: pull-off strength SS = 6%.

[0129] It is initially planned to conduct step-by-step high-temperature tensile tests on unit A.

[0130] Step 5: Determine the quantitative model of temperature cycle deviation.

[0131] The tensile strength under the temperature cycle test conditions was calculated according to formula (2). The calculation results are shown in Table 2.

[0132] Table 2 Calculation results of tensile strength under temperature cycle test conditions

[0133]

[0134] Step 6: Determine the temperature cycling deviation level.

[0135] According to the design characteristics of the product, if the number of cycles in the temperature cycle deflection test of single machine A is too large, it is easy to cause unnecessary life loss, which is not a weak link of the product. Therefore, when the number of temperature cycles is selected as 4, the deflection temperature range and temperature change rate are used as the test design parameters for formulating different deflection levels.

[0136] A single machine pull-off level 1: initial high temperature and corresponding time, pull-off level 2: pull-off strength SS = 2%, pull-off level 3: strength SS = 4%, pull-off level 4: pull-off strength SS = 6%.

[0137] It is initially planned to conduct cross-stage temperature cycle tensile test on unit A.

[0138] Step 7: Establish initial conditions for the experimental subjects.

[0139] The potential application models of A single unit are all liquid launch vehicle models. Therefore, the qualification level conditions of all potential application models of this product are encapsulated by the maximum operating conditions, and the conditions after encapsulation are used as the initial conditions. The initial conditions are as follows:

[0140] (1) High temperature initial conditions: high temperature 60℃, duration 4h.

[0141] (2) Initial temperature cycle conditions: -40℃~+60℃, single cycle time is 4h, and the number of cycles is 2.

[0142] Step 8: Adjust the pull-off cutoff level.

[0143] The coordination content for single machine A is as follows:

[0144] (1) Use the technical specification limits as the initial test conditions, see the specific conditions in the example in step 7;

[0145] (2) In order to find the weak link of unit A and improve its design and process, the stress level corresponding to the deflection cutoff level must exceed its working limit;

[0146] (3) The reliability of A single machine before the deflection test was evaluated to be 0.998, which basically meets the model requirements. The reliability improvement target is 0.999. The reliability does not need to be improved by an order of magnitude. Therefore, the stress level corresponding to the deflection cutoff level does not need to exceed its damage limit, and it also does not need to exceed its design limit.

[0147] (4) Based on the above coordination, the final tensile strength and grade are as follows:

[0148] a) High temperature deflection: Deflection level 1 is the initial test condition, and deflection strength of deflection level 2 is 2.5%

[0149] (Follow the sequence number 1 in Table 1), the tensile strength of the tensile level three is 4% (follow the sequence number 4 in Table 1), the tensile strength of the tensile level four is 6% (follow the sequence number 5 in Table 1), and the four levels are implemented in sequence.

[0150] b) Temperature Cycling Tensile Test: A level 4 tensile test was conducted, with a tensile strength of 5.8% (performed according to cycle number 4, sequence number 7 in Table 2).

[0151] Step 9: Troubleshooting and classification.

[0152] A single machine carries out the pull-out test according to the determined level. The faults and treatment measures during the test are as follows:

[0153] (1) No failure occurred during the high-temperature test. This is because the pull-off cutoff level did not exceed the operating limit or the design limit. The test confirmed that the A unit can withstand higher temperatures, verifying its design margin.

[0154] (2) During the temperature cycle test, a fault occurred in which the bit error rate of received data exceeded the index requirement. The test was terminated. The fault location confirmed that the antenna module was the weak link of the product. The design of this part of the printed circuit board was imperfect, resulting in its inability to withstand temperature changes.

[0155] (3) For any faults during the temperature cycle, the faulty component (antenna) is temporarily replaced and placed in the test facility to continue the test until the test is completed.

[0156] Step 10: Analysis and improvement of weak links.

[0157] Through deflection testing, the product's weak link was identified as the antenna. Subsequently, the original A-unit circularly polarized microstrip antenna was redesigned, optimizing the antenna structure and antenna pattern. The polarization was changed to linear polarization. The antenna baseplate was also raised and the baseplate material was changed. These improvements are expected to improve product reliability. The design team will conduct further environmental and reliability tests on the improved A-unit to verify its impact.

[0158] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

[0159] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A thermal environment tensile test method for electronic products, characterized in that: include: Determine the design characteristics of the test object as input for its quantitative pull-off test; Determine the tensile test limit of the test object based on the design characteristics of the test object; Determine the high-temperature deflection quantitative model and deflection grade, the temperature cycle deflection quantitative model and temperature cycle deflection grade; Establish initial conditions for test subjects; Adjust the cut-off level of the pull-out test; Perform a tensile test according to the previous settings and obtain the tensile test results for subsequent analysis of the weak links of the test object; The high temperature tensile strength quantitative model is: SS=1-exp(-0.0017(ΔT+0.6) 0.6 t) Among them, SS is the tensile strength, which actually represents the impact of the corresponding environmental stress on electronic products; ΔT is the tensile range, ΔT=(T U -T0), ℃; T U is the pulling temperature; T0 is the initial high temperature; t is the high temperature test holding time, in hours; The temperature cycle deflection quantitative model includes: SS=0.1-0.1*exp{-0.0017(ΔT+0.6) 0.6 [ln(e+v)] 3 N} Where SS is the tensile strength; ΔT is the tensile range, ΔT=(T U -T0), ℃; T U is the bias temperature cycle range; T0 is the initial temperature cycle range; N is the number of cycles; e is the base of the natural logarithm; v is the temperature change rate in °C / min. When the heating and cooling rates are different, the average temperature change rate is taken; v = (|V1| + |V2|) / 2, where V1 is the heating rate and V2 is the cooling rate. When a fault occurs during the pull-off test, the following method should be used to handle the fault: When a fault is confirmed, stop the test, restore the temperature in the test chamber to normal atmospheric conditions, and then remove the test object; For non-responsible faults, repair the test object and restore it to the state before the fault occurs before continuing the test; For responsible faults, the test is suspended, the fault is corrected, the design or process improvement of the test object is implemented, and the test is resumed after the test object implements the corrective measures; After the functional performance of the subjects has fully recovered, the test will continue; The design characteristics of the test object include the design plan, design requirements document, circuit diagram, functional block diagram, functional flow chart, functional performance indicators, fault judgment criteria, detection and monitoring methods, working conditions and working environment, historical usage data of the test object, reliability design analysis data of the test object, and failure data during field use; The tensile test limits of the test object include: technical specification limit, design limit, working limit and destruction limit; The method for adjusting the cut-off level of the tensile test is as follows: the stress level corresponding to the tensile cut-off level exceeds the product design limit or working limit; When there is no need to improve the product reliability level by an order of magnitude or more, the stress level corresponding to the deflection cutoff level does not exceed its destruction limit; When the product reliability level needs to be improved by an order of magnitude or more, the stress level corresponding to the deflection cutoff level exceeds its damage limit; The specific tensile strength under each tensile strength level may fluctuate by ±0.5%; The technical specification limit is used as the initial test condition for the product, and its stress level is not used as the cutoff level for deflection.

2. The electronic product thermal environment tensile test method according to claim 1, characterized in that: The tensile strength level includes four levels, namely, level 1: initial high temperature and corresponding time, level 2: tensile strength SS=2%, level 3: tensile strength SS=4%, and level 4: tensile strength SS=6%.

3. The electronic product thermal environment tensile test method according to claim 1, characterized in that: The temperature cycle tensile strength level includes four levels, namely, level 1: initial temperature cycle range, temperature change rate and corresponding number of cycles, level 2: tensile strength SS = 2%, level 3: tensile strength SS = 4%, level 4: tensile strength SS = 6%.

4. The thermal environment tensile test method for electronic products according to claim 1, characterized in that: The method for formulating the initial conditions of the test subject is any of the following conditions: First condition: select a certain model identification level condition as the initial condition; Second condition: Envelope the identification-level conditions of the potential application model of the electronic product according to certain principles, and use the conditions after enveloping as the initial conditions; The third condition: select a certain model acceptance level condition as the initial condition; The fourth condition: Envelope the acceptance level conditions of the potential application model of the electronic product according to certain principles, and use the enveloped conditions as the initial conditions Fifth condition: The most severe conditions experienced by the test object in its historical or expected use environment are used as the initial conditions; Sixth condition: Use the conditions given in the general specifications or standards of the test object as the initial conditions.

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