Method and apparatus for solder fatigue life prediction considering intermetallic compound growth

Abstract

The application discloses a solder fatigue life prediction method and device considering intermetallic compound growth, and the method comprises the following steps: carrying out temperature cycle simulation on a plurality of IMC layer thickness finite element models to obtain a first relationship curve of solder shearing plastic strain amplitude changing with IMC layer thickness; converting the first relationship curve into a second relationship curve of solder cumulative damage in a single time period changing with IMC layer thickness according to the average damage period of the solder and the reciprocal relationship of the damage; calculating an IMC layer thickness third relationship curve changing with time period number based on an IMC layer growth formula; obtaining a fourth relationship curve of solder cumulative damage in a single time period changing with time period number by combining the third relationship curve and the second relationship curve; and integrating the fourth relationship curve by using a continuous damage cumulative theory formula, so that the solder fatigue life is obtained when the integral sum of the cumulative damage in a plurality of time periods reaches 1, and the accuracy of solder fatigue life prediction is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of solder fatigue life prediction, and particularly relates to a solder fatigue life prediction method and device considering intermetallic compound growth. BACKGROUND

[0002] With the continuous reduction of the process size of chips and the gradual conversion of two-dimensional integration to three-dimensional integration, the size of the solder structure in the chip is also continuously reduced, and the proportion of the intermetallic compound (IMC) layer formed between the solder and the under bump metallization (UBM) in the total volume of the solder joint gradually increases. The connection principle of the solder and the under bump metallization is that the solder and the under bump metallization are mutually dissolved and diffused, and a metallurgical reaction occurs to form an IMC layer, thereby forming a firm bond. Although the IMC layer formed at the connection interface can help form a good solder joint, since the IMC layer itself has the tendency of brittleness and structural defects, therefore, an excessively thick IMC layer can damage the mechanical and electrical properties of the connection.

[0003] From the BGA (Ball Grid Array) packaging, QFP (Quad Flat Package) packaging and other packaging forms connecting chips and printed circuit boards (PCB, Printed Circuit Board), to the controlled collapse chip connection (C4, Controlled Collapse Chip Connect) in flip chip, to the micro-bump connecting through silicon via (TSV, Through Silicon Via) in three-dimensional integration, the solder volume used in different positions is also different. With the gradual reduction of the solder volume, the influence of the IMC layer growth on the solder life prediction is increasingly serious. Especially under temperature cycle loading, the IMC layer will grow significantly during high temperature holding, and considering the significant meaning of the IMC layer to accurately predict the solder life. The traditional experimental method to predict the fatigue life of the chip has problems such as high cost and long cycle, therefore, finite element simulation gradually becomes one of the effective methods to replace specific experiments to simulate experimental environment.

[0004] However, the existing fatigue life prediction method does not consider the dynamic changes of the IMC layer during loading, especially when the load contains high temperature conditions, the significant growth of the IMC layer will inevitably affect the solder fatigue life. In addition, the existing finite element simulation method is difficult to effectively simulate the dynamic changes of the IMC layer, therefore, the accuracy of the traditional life prediction method is too low. SUMMARY

[0005] In order to solve the above problems existing in the prior art, the present application provides a solder fatigue life prediction method and device considering intermetallic compound growth.

[0006] The technical problem to be solved by the present application is solved by the following technical scheme:

[0007] In a first aspect, the present application provides a solder fatigue life prediction method considering intermetallic compound growth, which comprises:

[0008] A plurality of finite element models are constructed according to the structure parameters of a device to be predicted; the thickness of the IMC layer in each finite element model is different;

[0009] Temperature cycle simulation is performed on the plurality of finite element models to obtain a first relationship curve representing the change of the shear plastic strain amplitude of the solder with the thickness of the IMC layer;

[0010] The average failure period of the solder is calculated based on the shear plastic strain amplitude of the solder, and the first relationship curve is converted into a second relationship curve representing the change of the cumulative damage of the solder in a single time period with the thickness of the IMC layer according to the inverse relationship between the average failure period and the damage of the solder;

[0011] A third relationship curve representing the change of the thickness of the IMC layer with the number of time periods is calculated according to an IMC layer growth formula and the plurality of finite element models, and the third relationship curve and the second relationship curve are solved to obtain a fourth relationship curve representing the change of the cumulative damage of the solder in a single time period with the number of time periods;

[0012] The fourth relationship curve is integrated according to a continuous damage accumulation theory formula, and when the integral sum of the cumulative damage in a plurality of time periods reaches 1, the plurality of time periods are taken as the solder fatigue life of the device to be predicted.

[0013] Optionally, the temperature cycle simulation on the plurality of finite element models to obtain the first relationship curve representing the change of the shear plastic strain amplitude of the solder with the thickness of the IMC layer comprises:

[0014] The temperature cycle simulation on the plurality of finite element models according to a preset temperature change rate to obtain the first relationship curve representing the change of the shear plastic strain amplitude of the solder with the thickness of the IMC layer; the preset temperature change rate is less than 15℃ / min.

[0015] Optionally, the calculation of the average failure period of the solder based on the shear plastic strain amplitude of the solder comprises:

[0016] Based on the shear plastic strain amplitude of the solder, the average failure cycle of the solder is calculated using the Engelmaier-modified Coffin-Manson formula.

[0017] Optionally, the continuous damage accumulation theoretical formula is determined based on Miner's fatigue cumulative damage theoretical formula;

[0018] The Miner fatigue cumulative damage theory formula is:

[0019]

[0020] Wherein, D represents the cumulative damage of the solder in a single cycle; n i Indicates the stress load S i The number of time periods; N i Indicates the stress load S i Solder fatigue life; i = 1, 2, ..., m; m represents the total number of stress loads.

[0021] Optionally, integrating the fourth relationship curve according to the continuous damage accumulation theory formula includes:

[0022]

[0023] Among them, D 总 represents the integral sum of the accumulated damage in the multiple time periods; 总

[0024] =1, N is equal to the average failure cycle N of the solder f ; D(N) represents the fourth relationship curve.

[0025] In a second aspect, the present invention provides a solder fatigue life prediction device taking into account intermetallic compound growth, the solder fatigue life prediction device comprising:

[0026] A finite element model building module is used to build multiple finite element models according to the structural parameters of the device to be predicted; the thickness of the IMC layer in each finite element model is different;

[0027] a first relationship curve determination module, configured to perform temperature cycle simulation on the plurality of finite element models to obtain a first relationship curve representing a change in shear plastic strain amplitude of the solder as a function of thickness of the IMC layer;

[0028] a second relationship curve determining module, configured to calculate an average damage cycle of the solder based on the shear plastic strain amplitude of the solder, and convert the first relationship curve into a second relationship curve representing the cumulative damage of the solder in a single time cycle varying with the thickness of the IMC layer according to the average damage cycle and the inverse relationship of the damage of the solder;

[0029] a fourth relationship curve determining module, configured to calculate a third relationship curve representing the thickness of the IMC layer varying with the number of time cycles according to an IMC layer growth formula and the plurality of finite element models, and obtain a fourth relationship curve representing the cumulative damage of the solder in a single time cycle varying with the number of time cycles by combining the third relationship curve and the second relationship curve;

[0030] a solder fatigue life determining module, configured to integrate the fourth relationship curve according to a continuous damage accumulation theory formula, and take the plurality of time cycles as the solder fatigue life of the to-be-predicted device when the integral sum of the cumulative damage in the plurality of time cycles reaches 1.

[0031] Optionally, the first relationship curve determining module is specifically configured to perform temperature cycle simulation on the plurality of finite element models according to a preset temperature change rate to obtain the first relationship curve representing the shear plastic strain amplitude of the solder varying with the thickness of the IMC layer; and the preset temperature change rate is less than 15 ℃ / min.

[0032] Optionally, the second relationship curve determining module calculates the average damage cycle of the solder based on the shear plastic strain amplitude of the solder, and the method includes:

[0033] calculating the average damage cycle of the solder by using an Engelmaier-modified Coffin-Manson formula based on the shear plastic strain amplitude of the solder.

[0034] Optionally, the continuous damage accumulation theory formula is determined based on a Miner fatigue cumulative damage theory formula.

[0035] The Miner fatigue cumulative damage theory formula is:

[0036]

[0037] wherein D represents the cumulative damage of the solder in a single cycle; n i represents the number of time cycles corresponding to the stress load S i ; N i represents the solder fatigue life corresponding to the stress load S i ; i = 1, 2,..., m; and m represents the total number of stress loads.

[0038] Optionally, the solder fatigue life determining module integrates the fourth relationship curve according to a continuous damage accumulation theory formula.

[0039]

[0040] wherein D 总 represents the integral sum of the accumulated damage in the plurality of time periods; when D 总 = 1, N is equal to the average damage period N f of the solder; and D(N) represents the fourth relationship curve.

[0041] The present application provides a solder fatigue life prediction method considering intermetallic compound growth, a third relationship curve representing the change of the thickness of the IMC layer with the number of time periods is calculated according to the IMC layer growth formula and a plurality of finite element models with different IMC layer thicknesses, the third relationship curve and a second relationship curve representing the change of the accumulated damage of the solder in a single period with the thickness of the IMC layer are solved in parallel to obtain a fourth relationship curve representing the change of the accumulated damage of the solder in a single time period with the number of time periods. The fourth relationship curve is integrated according to a continuous damage accumulation theory formula, when the integral sum of the accumulated damage in the plurality of time periods reaches 1, the plurality of time periods are taken as the solder fatigue life of the device to be predicted, the finite element models with different IMC layer thicknesses are fitted on the time period by the IMC layer growth formula, the purpose of simulating the continuous change of the IMC layer thickness with time is achieved, thereby realizing the solder fatigue life prediction considering the change of the IMC layer thickness, and improving the accuracy of the solder fatigue life prediction.

[0042] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a flowchart of a solder fatigue life prediction method considering intermetallic compound growth provided by an embodiment of the present application;

[0044] Figure 2 is a schematic diagram of the accumulated damage of the solder in a single time period provided by an embodiment of the present application;

[0045] Figure 3 is a structural schematic diagram of a solder fatigue life prediction device considering intermetallic compound growth provided by an embodiment of the present application. DETAILED DESCRIPTION

[0046] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0047] In order to solve the problems that the existing fatigue life prediction method is difficult to simulate the dynamic change of the IMC layer and the prediction accuracy is low, the embodiment of the present application provides a solder fatigue life prediction method considering the growth of intermetallic compounds, referring to Figure 1 , Figure 1 is a flowchart of a solder fatigue life prediction method considering the growth of intermetallic compounds provided by the embodiment of the present application, and specifically includes the following steps:

[0048] In step S101, a plurality of finite element models are constructed according to the structure parameters of the device to be predicted; the thickness of the IMC layer in each finite element model is different.

[0049] In the embodiment of the present application, the device to be predicted can be various chips or PCB circuit boards and the like.

[0050] In the embodiment of the present application, the structure parameters are determined according to the device to be predicted. For example, if the device to be predicted is a C4 bump of a chip, the structure parameters can be the size of the upper and lower pads of the device to be predicted, the thickness of the pad, the diameter of the bump, the height of the bump, the spacing between the bumps, the number of bumps, and the length, width and height of the chip, the length, width and height of the plastic package, the length, width and height of the substrate, and the like. Specifically, the structure parameters can be selected by the skilled person according to the device to be predicted, which is not limited herein.

[0051] In the embodiment of the present application, the construction of the finite element model can be realized by inputting the structure parameters of the device to be predicted into the finite element analysis software. For example, the finite element analysis software can be ANSYS, Abaqus or COMSOL Multiphysics and the like.

[0052] The IMC layer refers to a compound layer formed at the interface between the solder and the metal layer under the bump of the chip, such as the copper-tin (Cu-Sn) interface, through an interfacial chemical reaction during welding.

[0053] In the embodiment of the present application, based on the structure parameters of the device to be predicted, a plurality of finite element models can be established by setting IMC layers with different thicknesses, that is, for each finite element model, only the thickness of the IMC layer in the finite element model is different, and the other structure parameters are completely the same.

[0054] In the embodiment of the present application, at least 10 finite element models with different thicknesses of the IMC layer can be established, and considering the growth of the IMC layer during welding, at least 10 thicknesses of the IMC layer can be selected at equal intervals from 2.5 μm to the estimated final thickness to establish the finite element models. It should be noted that in each finite element model, the sum of the thickness of the IMC layer and the thickness of the solder is assumed to be constant.

[0055] In step S102, temperature cycle simulation is performed on the plurality of finite element models to obtain a first relationship curve representing the change of the shear plastic strain amplitude of the solder with the thickness of the IMC layer.

[0056] In the embodiment of the present application, during the temperature cycle, high temperature promotes the growth of the IMC layer, i.e., the thickness of the IMC layer increases. The IMC layer is an intermetallic compound layer formed between the solder and the under bump metallization layer of the chip during the soldering process.

[0057] In the embodiment of the present application, the shear plastic strain amplitude of the solder refers to the amplitude of the change of the shear plastic strain of the solder per time cycle after the periodic stabilization.

[0058] The temperature cycle simulation is performed on the plurality of finite element models to obtain a first relationship curve representing the change of the shear plastic strain amplitude of the solder with the thickness of the IMC layer.

[0059] In the embodiment of the present application, if no special requirement is made, the temperature change range for the temperature cycle simulation on the plurality of finite element models should be selected from the national standard.

[0060] In step S103, the average failure cycle of the solder is calculated based on the shear plastic strain amplitude of the solder, and the first relationship curve is converted into a second relationship curve representing the change of the cumulative damage of the solder in a single time cycle with the thickness of the IMC layer according to the inverse relationship between the average failure cycle and the damage of the solder.

[0061] In the embodiment of the present application, the average failure cycle of the solder can be calculated based on the shear plastic strain amplitude of the solder by using a low cycle fatigue life calculation formula, such as the Coffin-Manson model. The Coffin-Manson model is widely used to predict the low cycle fatigue life, i.e., the average failure cycle, of the soldering alloy according to the plastic strain range.

[0062] In the embodiment of the present application, the average failure cycle of the solder is calculated based on the shear plastic strain amplitude of the solder, including:

[0063] Based on the shear plastic strain amplitude of the solder, the average failure cycle of the solder is calculated by using the Coffin-Manson formula modified by Engelmaier (a model for predicting the fatigue life of a device in a temperature cycle environment). The Coffin-Manson formula model takes parameters such as the cycle frequency, i.e., the time cycle frequency, the solder and substrate temperature into the equation.

[0064] Specifically, the Coffin-Manson formula modified by Engelmaier is as shown in the following formula:

[0065]

[0066] wherein, N f represents the average failure period of the solder; Δγ represents the shear plastic strain amplitude of the solder; ε, f represents the fatigue ductility coefficient, and the empirical value thereof for the solder is 0.325; c represents the fatigue ductility index.

[0067] In the embodiment of the present application, the fatigue ductility index can be calculated according to the following formula:

[0068]

[0069] wherein, represents the average solder joint temperature, i.e. the aforementioned substrate temperature, in units of ℃, and f is the cycle frequency, in units of cycles (periods) per day.

[0070] In the embodiment of the present application, the cumulative damage of the solder in a single time period is calculated according to the inverse relationship between the average failure period of the solder and the damage of the solder, i.e. the first relationship curve of the plastic strain amplitude-IMC layer thickness is converted into the second relationship curve of the solder single-period damage-IMC layer thickness according to the low-cycle fatigue life formula which considers the inverse relationship between the damage of the solder and the average failure period of the solder.

[0071] In step S104, a third relationship curve representing the change of the thickness of the IMC layer with the number of time periods is calculated according to the IMC layer growth formula and the plurality of finite element models, and the third relationship curve and the second relationship curve are solved to obtain a fourth relationship curve representing the change of the cumulative damage of the solder in a single time period with the number of time periods.

[0072] In the embodiment of the present application, the IMC layer growth formula conforms to the Dybkov equation, i.e. the growth thickness is in a positive proportional relationship with the square root of the temperature loading time, and it is noted that the temperature loading time takes the high-temperature holding time in the temperature cycle.

[0073] Under the condition of single-temperature stress, the growth of the IMC layer at the copper-tin (Cu-Sn) interface caused by thermal diffusion is mainly dominated by the thermal diffusion of copper atoms caused by the temperature gradient, and the growth thickness of the IMC layer is in a positive proportional relationship with the square root of the temperature loading time, and the IMC layer growth formula under the condition of single-temperature stress is:

[0074]

[0075] wherein, x AB represents the thickness of the IMC layer corresponding to the time t; x0 represents the initial thickness of the IMC layer; C Cu represents the Cu atom concentration in the Cu pad, and the value thereof is 8.44×10 22 at. / cm 3 ; C Cu / Snrepresents the Cu atomic concentration in the solder, and has a value of 1.1 x 10 20 at. / cm 3 ; represents the Cu atomic concentration in the IMC, and has a value of 3.7 x 10 22 at. / cm 3 ; represents the thermal diffusion coefficient of the Cu atoms in the IMC layer, the change rule of T with temperature T is:

[0076]

[0077] wherein the unit of T is ℃; the unit of D is cm 2 / s.

[0078] Based on this, the growth formula of the IMC layer under the corresponding temperature cycle condition can be calculated according to the above parameters, and then the third relationship curve representing the change of the thickness of the IMC layer with the number of time periods can be obtained according to the growth formula of the IMC layer.

[0079] By combining the third relationship curve and the second relationship curve, the fourth relationship curve representing the change of the cumulative damage of the solder in a single time period with the number of time periods can be obtained.

[0080] In addition, for different metal material interfaces or loading conditions, the growth formula of the IMC layer can be replaced by the IMC growth formula corresponding to the condition for calculation.

[0081] Step S105, according to the continuous damage accumulation theory formula, the fourth relationship curve is integrated, when the integral sum of the cumulative damage in multiple time periods reaches 1, the multiple time periods are taken as the solder fatigue life of the device to be predicted.

[0082] For life calculation under multiple stresses, the Miner fatigue cumulative damage theory considers that the fatigue damage caused by each stress to the material is independent of each other, and the total cumulative damage can be obtained by linearly accumulating the damage caused by each stress. According to the Miner fatigue cumulative damage theory, for an object with unchanged loading condition, the cumulative damage D in each period is equal to the reciprocal of the fatigue life (the number of time periods), and when the total damage accumulation reaches 1, the device is determined to be invalid.

[0083] And for the case where the loading condition changes with time, the cumulative damage in each time period can be seen from Figure 2 , Figure 2is a schematic diagram of cumulative damage of solder in a single time period provided by the embodiment of the present application, wherein the abscissa represents the cycle number N, i.e. the number of time periods, and the ordinate represents the damage D. When the single period time is small enough compared with the total fatigue life, the discrete damage in each time period can be regarded as a function continuously changing with time as shown by the curve, i.e. the damage in each time period can be regarded as a continuously changing process, and the Miner cumulative damage theory is extended from summation to integration to obtain the continuous damage cumulative theory formula. Further, the fourth change curve is integrated according to the continuous damage cumulative theory formula, and when the total sum of the cumulative damage in the multiple time periods reaches 1, i.e. the integral area reaches 1, the number of the multiple time periods is taken as the predicted solder fatigue life of the device to be predicted, i.e. the solder fatigue life considering the IMC layer thickness variation is obtained at this time. Figure 2 The curve shown in the curve is a function continuously changing with time, i.e. the damage in each time period can be regarded as a continuously changing process, and the Miner cumulative damage theory is extended from summation to integration to obtain the continuous damage cumulative theory formula. Further, the fourth change curve is integrated according to the continuous damage cumulative theory formula, and when the total sum of the cumulative damage in the multiple time periods reaches 1, i.e. the integral area reaches 1, the number of the multiple time periods is taken as the predicted solder fatigue life of the device to be predicted, i.e. the solder fatigue life considering the IMC layer thickness variation is obtained at this time.

[0084] In the embodiment of the present application, the third relationship curve representing the change of the thickness of the IMC layer with the number of time periods is calculated according to the IMC layer growth formula and the finite element models with different thicknesses of the IMC layer, and the third relationship curve and the second relationship curve representing the change of the cumulative damage of the solder in a single period with the thickness of the IMC layer are combined to obtain the fourth relationship curve representing the change of the cumulative damage of the solder in a single time period with the number of time periods. The fourth relationship curve is integrated according to the continuous damage cumulative theory formula, and when the integral sum of the cumulative damage in the multiple time periods reaches 1, the number of the multiple time periods is taken as the solder fatigue life of the device to be predicted, the finite element models with different thicknesses of the IMC layer are fitted on the time period by the IMC layer growth formula to simulate the continuous change of the thickness of the IMC layer with time, thereby realizing the prediction of the solder fatigue life considering the change of the thickness of the IMC layer and improving the accuracy of the prediction of the solder fatigue life.

[0085] In one implementation, the multiple finite element models are simulated for temperature cycling to obtain the first relationship curve representing the change of the shear plastic strain amplitude of the solder with the thickness of the IMC layer, including:

[0086] The multiple finite element models are simulated for temperature cycling according to the preset temperature change rate to obtain the first relationship curve representing the change of the shear plastic strain amplitude of the solder with the thickness of the IMC layer; the preset temperature change rate is less than 15℃ / min.

[0087] In the embodiment of the present application, the multiple finite element models are simulated for temperature cycling according to the preset temperature change rate, and the thickness of the IMC layer in the finite element model is taken as the independent variable and the shear plastic strain amplitude of the solder in the finite element model is taken as the dependent variable to perform exponential fitting, to obtain the plastic strain amplitude-IMC layer thickness curve, i.e. the first relationship curve.

[0088] Considering that thermal expansion and shrinkage of most materials at a rapid temperature change will cause a large stress concentration, which can initiate micro-cracks, delamination or failure of solder joints, in addition, a rapid temperature change rate can also introduce errors, affecting the calculation results of strain and stress. Therefore, it is necessary to control the temperature change rate in the temperature cycle simulation, and by setting a reasonable change rate, the obtained data can be more reliable, which is helpful for subsequent analysis and decision-making.

[0089] Based on the above considerations, in the embodiment of the application, the preset temperature change rate is preferably less than 15℃ / min.

[0090] In an implementation manner, the continuous damage accumulation theory formula is determined based on a Miner fatigue cumulative damage theory formula.

[0091] The Miner fatigue cumulative damage theory formula is:

[0092]

[0093] wherein, D represents the cumulative damage of the solder in a single cycle; n i represents the number of time cycles corresponding to the stress load S i ; N i represents the fatigue life of the solder corresponding to the stress load S i ; i = 1, 2,..., m; and m represents the total number of stress loads.

[0094] Integrating the fourth relationship curve according to the continuous damage accumulation theory formula includes:

[0095]

[0096] wherein, D 总 represents the integral sum of the cumulative damage in a plurality of time cycles; when D 总 = 1, N is equal to the average damage cycle N f of the solder; and N f D(N) represents the fourth relationship curve. In addition, when D 总 ≠ 1, N is equal to the number of cycles for damage calculation.

[0097] According to simulation experiment instances, the solder fatigue life prediction method considering intermetallic compound growth provided by the embodiment of the application is 30% more accurate than the existing life prediction method without considering the growth of the IMC layer.

[0098] Based on the same inventive concept, the embodiment of the application also provides a solder fatigue life prediction device considering intermetallic compound growth, which is described in detail in the description of the solder fatigue life prediction method. Figure 3 , Figure 3It is a kind of structure schematic view of solder fatigue life prediction device considering intermetallic compound growth provided by the embodiment of the present application, and the solder fatigue life prediction device comprises:

[0099] The finite element model construction module 301 is used to construct a plurality of finite element models according to the structural parameters of the device to be predicted;The thickness of the IMC layer in each finite element model is different.

[0100] The first relationship curve determination module 302 is used to simulate temperature cycling for the plurality of finite element models, to obtain a first relationship curve representing the change of the shear plastic strain amplitude of the solder with the thickness of the IMC layer.

[0101] The second relationship curve determination module 303 is used to calculate the average failure period of the solder based on the shear plastic strain amplitude of the solder, and convert the first relationship curve into a second relationship curve representing the change of the cumulative damage of the solder in a single time period with the thickness of the IMC layer according to the inverse relationship between the average failure period and the damage of the solder.

[0102] The fourth relationship curve determination module 304 is used to calculate a third relationship curve representing the change of the thickness of the IMC layer with the number of time periods according to the IMC layer growth formula and the plurality of finite element models, and combine the third relationship curve and the second relationship curve to obtain a fourth relationship curve representing the change of the cumulative damage of the solder in a single time period with the number of time periods.

[0103] The solder fatigue life determination module 305 is used to integrate the fourth relationship curve according to the continuous damage accumulation theory formula, and when the integral sum of the cumulative damage in a plurality of time periods reaches 1, the plurality of time periods are taken as the solder fatigue life of the device to be predicted.

[0104] In the embodiment of the present application, the third relationship curve representing the change of the thickness of the IMC layer with the number of time periods is calculated according to the IMC layer growth formula and the plurality of finite element models with different thicknesses of the IMC layer, and the third relationship curve and the second relationship curve representing the change of the cumulative damage of the solder in a single period with the thickness of the IMC layer are combined to obtain a fourth relationship curve representing the change of the cumulative damage of the solder in a single time period with the number of time periods. The fourth relationship curve is integrated according to the continuous damage accumulation theory formula, and when the integral sum of the cumulative damage in a plurality of time periods reaches 1, the plurality of time periods are taken as the solder fatigue life of the device to be predicted. The finite element models with different thicknesses of the IMC layer are fitted on the time period through the IMC layer growth formula, to achieve the purpose of simulating the continuous change of the thickness of the IMC layer with time, thereby realizing the solder fatigue life prediction considering the change of the thickness of the IMC layer, and improving the accuracy of the solder fatigue life prediction.

[0105] Optionally, the first relationship curve determining module is specifically configured to perform temperature cycle simulation on the plurality of finite element models according to a preset temperature change rate to obtain a first relationship curve representing a change of a shear plastic strain amplitude of the solder with respect to a thickness of the IMC layer; and the preset temperature change rate is less than 15℃ / min.

[0106] Optionally, the second relationship curve determining module is configured to calculate the average failure period of the solder based on the shear plastic strain amplitude of the solder, including:

[0107] The average failure period of the solder is calculated based on the shear plastic strain amplitude of the solder by using an Engelmaier-modified Coffin-Manson formula.

[0108] Optionally, the continuous damage accumulation theory formula is determined based on a Miner fatigue cumulative damage theory formula.

[0109] The Miner fatigue cumulative damage theory formula is:

[0110]

[0111] wherein D represents a cumulative damage of the solder in a single period; n i represents a number of time periods corresponding to a stress load S i ; N i represents a solder fatigue life corresponding to the stress load S i ; i = 1, 2, …, m; and m represents a total number of stress loads.

[0112] Optionally, the solder fatigue life determining module is configured to integrate the fourth relationship curve according to the continuous damage accumulation theory formula, including:

[0113]

[0114] wherein D 总 represents an integrated sum of cumulative damages in the plurality of time periods; when D 总 = 1, N is equal to the average failure period N f of the solder; and D(N) represents the fourth relationship curve.

[0115] It should be noted that the terms "first", "second", and so on are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the application described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of devices and methods consistent with some aspects of the present application.

[0116] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms is not necessarily directed to the same embodiment or example. Moreover, the specific features or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present specification.

[0117] Although the present application is described herein in conjunction with various embodiments, other variations of the disclosed embodiments can be understood and implemented by those skilled in the art with reference to the drawings and the disclosure. In the description of the present application, the word "comprising" does not exclude other components or steps, "one" or "an" does not exclude a plurality, and "plurality" means two or more, unless otherwise explicitly specified. In addition, some measures are described in different embodiments, but this does not mean that these measures cannot be combined to produce good results.

[0118] For device embodiments, since they are basically similar to method embodiments, the description is relatively simple, and the relevant part can be referred to the part of the method embodiment.

[0119] It should be noted that the device of the embodiments of the present application is a device applying the above-mentioned solder fatigue life prediction method considering intermetallic compound growth, and all embodiments of the above-mentioned solder fatigue life prediction method considering intermetallic compound growth are applicable to the device, and can achieve the same or similar beneficial effects.

[0120] The above is a further detailed description of the present application in conjunction with specific preferred embodiments, and the specific implementation of the present application cannot be limited to these descriptions. For those skilled in the art to which the present application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, which should be regarded as falling within the scope of protection of the present application.

Claims

1. A solder fatigue life prediction method considering intermetallic compound growth, characterized by, The solder fatigue life prediction method comprises: a plurality of finite element models are constructed according to structure parameters of a device to be predicted; the thicknesses of IMC layers in the finite element models are different; temperature cycle simulation is performed on the plurality of finite element models to obtain a first relationship curve representing the change of the solder shearing plastic strain amplitude with the thickness of the IMC layer; the average damage period of the solder is calculated based on the solder shearing plastic strain amplitude, and the first relationship curve is converted into a second relationship curve representing the change of the cumulative damage of the solder in a single time period with the thickness of the IMC layer according to the reciprocal relationship between the average damage period and the damage of the solder; a third relationship curve representing the change of the thickness of the IMC layer with the number of time periods is calculated according to an IMC layer growth formula and the plurality of finite element models, and the third relationship curve and the second relationship curve are combined to obtain a fourth relationship curve representing the change of the cumulative damage of the solder in a single time period with the number of time periods; the fourth relationship curve is integrated according to a continuous damage accumulation theory formula, and when the integral sum of the cumulative damage in a plurality of time periods reaches 1, the plurality of time periods are taken as the solder fatigue life of the device to be predicted.

2. The solder fatigue life prediction method according to claim 1, characterized by, The temperature cycle simulation on the plurality of finite element models to obtain the first relationship curve representing the change of the solder shearing plastic strain amplitude with the thickness of the IMC layer comprises: temperature cycle simulation is performed on the plurality of finite element models according to a preset temperature change rate to obtain the first relationship curve representing the change of the solder shearing plastic strain amplitude with the thickness of the IMC layer; the preset temperature change rate is less than 15 ℃ / min.

3. The solder fatigue life prediction method according to claim 1, characterized by, The calculation of the average damage period of the solder based on the solder shearing plastic strain amplitude comprises: the average damage period of the solder is calculated based on the solder shearing plastic strain amplitude by using the Coffin-Manson formula modified by Engelmaier.

4. The solder fatigue life prediction method according to claim 1, characterized by, The continuous damage accumulation theory formula is determined based on a Miner fatigue cumulative damage theory formula; The Miner fatigue cumulative damage theory formula is: where D represents the cumulative damage of the solder over a single cycle; n i represents the number of time cycles corresponding to the stress load S i ; N i represents the solder fatigue life corresponding to the stress load S i ; i = 1, 2,..., m; and m represents the total number of stress loads.

5. The solder fatigue life prediction method according to claim 4, characterized by, The integration of the fourth relationship curve according to the continuous damage accumulation theory formula comprises: where D 总 represents the integral sum of the cumulative damage over the plurality of time periods; at D 总 = 1, N is equal to the average failure period N f of the solder; D(N) represents the fourth relationship curve.

6. A solder fatigue life prediction device considering intermetallic compound growth, characterized by, The solder fatigue life prediction device comprises: a finite element model construction module configured to construct a plurality of finite element models according to structure parameters of a device to be predicted; the thicknesses of IMC layers in the finite element models are different; a first relationship curve determination module configured to perform temperature cycle simulation on the plurality of finite element models to obtain a first relationship curve representing the change of the solder shearing plastic strain amplitude with the thickness of the IMC layer; a second relationship curve determination module configured to calculate the average damage period of the solder based on the solder shearing plastic strain amplitude, and convert the first relationship curve into a second relationship curve representing the change of the cumulative damage of the solder in a single time period with the thickness of the IMC layer according to the reciprocal relationship between the average damage period and the damage of the solder; a fourth relationship curve determination module, configured to determine a third relationship curve representing a change of thickness of the IMC layer with respect to a number of time periods according to the IMC layer growth formula and the plurality of finite element models, and to determine a fourth relationship curve representing a change of accumulated damage of the solder in a single time period with respect to the number of time periods by combining the third relationship curve and the second relationship curve; a solder fatigue life determination module, configured to integrate the fourth relationship curve according to a continuous damage accumulation theory formula, and to determine the solder fatigue life of the to-be-predicted device as a plurality of time periods when an integral sum of accumulated damage in the plurality of time periods reaches 1.

7. The solder fatigue life prediction apparatus according to claim 6, characterized by The first relationship curve determination module is specifically configured to perform temperature cycle simulation on the plurality of finite element models according to a preset temperature change rate, and to determine the first relationship curve representing a change of a shear plastic strain amplitude of the solder with respect to a thickness of the IMC layer. The preset temperature change rate is less than 15 ℃ / min.

8. The solder fatigue life prediction apparatus according to claim 6, characterized by, The second relationship curve determination module is configured to calculate the average failure period of the solder based on the shear plastic strain amplitude of the solder, including: The second relationship curve determination module is configured to calculate the average failure period of the solder based on the shear plastic strain amplitude of the solder, including:

9. The solder fatigue life prediction apparatus according to claim 6, characterized by, The continuous damage accumulation theory formula is determined based on a Miner fatigue cumulative damage theory formula. The Miner fatigue cumulative damage theory formula is: where D represents the cumulative damage of the solder over a single cycle; n i represents the number of time cycles corresponding to the stress load S i ; N i represents the solder fatigue life corresponding to the stress load S i ; i = 1, 2,..., m; and m represents the total number of stress loads.

10. The solder fatigue life prediction apparatus according to claim 9, characterized by The solder fatigue life determination module is configured to integrate the fourth relationship curve according to the continuous damage accumulation theory formula, including: where D 总 represents the integral sum of the cumulative damage over the plurality of time periods; at D 总 = 1, N is equal to the average failure period N f of the solder; D(N) represents the fourth relationship curve.

Images