Solder fatigue life prediction method and device considering growth of intermetallic compound

Abstract

The invention discloses a solder fatigue life prediction method and device considering intermetallic compound growth. The method comprises the following steps: performing temperature cycle simulation on a finite element model of a plurality of IMC layer thicknesses to obtain a first relation curve of the change of the shear plasticity strain amplitude of a solder along with the IMC layer thickness; converting the first relation curve into a second relation curve of accumulated damage of the welding flux in a single time period along with the change of the thickness of the IMC layer according to the average damage period of the welding flux and the reciprocal relation of the damage of the welding flux; calculating based on an IMC layer growth formula to obtain a third relation curve that the thickness of the IMC layer changes along with the time cycle number, and simultaneously establishing the third relation curve and the second relation curve to obtain a fourth relation curve that the accumulated damage of the solder in a single time cycle changes along with the time cycle number; and integrating the fourth relation curve by using a continuous damage accumulation theoretical formula, and obtaining the fatigue life of the solder when the integral sum of accumulated damage in a plurality of time periods reaches 1, so that the accuracy of predicting the fatigue life of the solder is improved.

Description

Technical Field

[0001] The invention belongs to the field of solder fatigue life prediction, and in particular relates to a solder fatigue life prediction method and device taking into account the growth of intermetallic compounds. Background Art

[0002] As the chip process size continues to decrease and the two-dimensional integration gradually turns to three-dimensional integration, the size of the solder structure in the chip is also shrinking, and the proportion of the intermetallic compound (IMC) layer formed between the solder and the under bump metallization (UBM) layer in the total volume of the solder joint is gradually increasing. The connection principle between the solder and the under bump metallization is that the solder and the under bump metallization layer dissolve and diffuse with each other, and a metallurgical reaction occurs to form an IMC layer, thereby forming a strong bond. Although the IMC layer formed at the connection interface can help form a good solder joint, due to the brittleness of the IMC layer itself and the tendency to produce structural defects, an overly thick IMC layer may damage the mechanical and electrical properties of the connection.

[0003] From BGA (Ball Grid Array) and QFP (Quad Flat Package) packages that connect chips to printed circuit boards (PCBs), to controlled collapse chip connections (C4) in flip chips, to micro-bumps that connect through silicon vias (TSVs) in three-dimensional integration, the volume of solder used in different locations is also different. As the volume of solder gradually decreases, the impact of IMC layer growth on solder life prediction becomes more and more serious. Especially under temperature cycle loads, the IMC layer will grow significantly when high temperature is maintained. Considering that the IMC layer is of significant significance for accurately predicting solder life. Using traditional experimental methods to predict chip fatigue life has problems such as high cost and long cycle, so finite element simulation has gradually become one of the effective methods to replace specific experiments to simulate experimental environments.

[0004] However, the existing fatigue life prediction methods do not take into account the dynamic changes of the IMC layer during loading, especially when the load includes high temperature conditions, the significant growth of the IMC layer will inevitably affect the fatigue life of the solder. In addition, the existing finite element simulation method is difficult to effectively simulate the dynamic changes of the IMC layer, so the accuracy of the traditional life prediction method is too low. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a method and device for predicting solder fatigue life taking into account the growth of intermetallic compounds.

[0006] The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides a solder fatigue life prediction method considering the growth of intermetallic compounds, the solder fatigue life prediction method comprising:

[0008] Construct 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;

[0009] Performing temperature cycle simulation on the multiple finite element models to obtain a first relationship curve representing a change in shear plastic strain amplitude of the solder with a change in thickness of the IMC layer;

[0010] Calculating an average failure cycle of the solder based on the shear plastic strain amplitude of the solder, and converting the first relationship curve into a second relationship curve characterizing the variation 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 cycle 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 cycles is calculated according to the IMC layer growth formula and the multiple 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 cycles;

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

[0013] Optionally, a temperature cycle simulation is performed on the multiple finite element models to obtain a first relationship curve characterizing the change in shear plastic strain amplitude of the solder with the thickness of the IMC layer, including:

[0014] The multiple finite element models are subjected to temperature cycle simulation according to a preset temperature change rate to obtain a first relationship curve characterizing the shear plastic strain amplitude of the solder changing with the thickness of the IMC layer; the preset temperature change rate is less than 15°C / min.

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

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

[0017] Optionally, the continuous damage accumulation theoretical formula is determined based on Miner fatigue accumulation 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 the growth of intermetallic compounds, 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 is used to perform temperature cycle simulation on the multiple finite element models to obtain a first relationship curve representing the shear plastic strain amplitude of the solder as a function of the thickness of the IMC layer;

[0028] a second relationship curve determination module, configured to calculate an 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 characterizing the variation 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;

[0029] a fourth relationship curve determination module, configured to calculate, according to the IMC layer growth formula and the plurality of finite element models, a third relationship curve characterizing the change of the thickness of the IMC layer with the number of time cycles, and to obtain, in conjunction with the third relationship curve and the second relationship curve, a fourth relationship curve characterizing the change of the cumulative damage of the solder in a single time period with the number of time cycles;

[0030] The solder fatigue life determination module is used to integrate the fourth relationship curve according to the continuous damage accumulation theoretical formula. When the integral sum of the accumulated damage in multiple time periods reaches 1, the multiple time periods are used as the solder fatigue life of the component to be predicted.

[0031] Optionally, the first relationship curve determination module is specifically used to perform temperature cycle simulation on the multiple finite element models according to a preset temperature change rate to obtain a first relationship curve characterizing the change in the shear plastic strain amplitude of the solder with the thickness of the IMC layer; the preset temperature change rate is less than 15°C / min.

[0032] Optionally, the second relationship curve determination module calculates the average failure period of the solder based on the shear plastic strain amplitude of the solder, including:

[0033] Based on the shear plastic strain amplitude of the solder, the average failure cycle of the solder is calculated using the Coffin-Manson formula modified by Engelmaier.

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

[0038] Optionally, the solder fatigue life determination module integrates the fourth relationship curve according to the continuous damage accumulation theory formula, including:

[0039]

[0040] Among them, D 总 represents the integral sum of the accumulated damage in the multiple time periods; 总 = 1, N is equal to the average failure cycle N of the solder f ; D(N) represents the fourth relationship curve.

[0041] The present invention provides a solder fatigue life prediction method considering the growth of intermetallic compounds. According to the IMC layer growth formula and the finite element model of different thicknesses of multiple IMC layers, a third relationship curve characterizing the change of the thickness of the IMC layer with the number of time cycles is calculated, and the third relationship curve and the second relationship curve characterizing the change of the cumulative damage of the solder in a single cycle with the thickness of the IMC layer are combined to obtain a fourth relationship curve characterizing the change of the cumulative damage of the solder in a single time period with the number of time cycles. The fourth relationship curve is integrated according to the continuous damage accumulation theory formula. When the integral sum of the cumulative damage in multiple time periods reaches 1, the multiple time periods are used as the solder fatigue life of the device to be predicted. The finite element model of different IMC layer thicknesses is fitted in the time period through the IMC layer growth formula to achieve the purpose of simulating the continuous change of the IMC layer thickness with time, 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 invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a flow chart of a method for predicting solder fatigue life taking into account the growth of intermetallic compounds provided by an embodiment of the present invention;

[0044] Figure 2 is a schematic diagram of cumulative damage of solder within a single time period provided by an embodiment of the present invention;

[0045] Figure 3 It is a schematic structural diagram of a solder fatigue life prediction device taking into account the growth of intermetallic compounds provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0047] In order to solve the problem that the existing fatigue life prediction method is difficult to simulate the dynamic changes of the IMC layer and has low prediction accuracy, the embodiment of the present invention provides a solder fatigue life prediction method considering the growth of intermetallic compounds, see Figure 1 , Figure 1 : is a flow chart of a method for predicting solder fatigue life considering intermetallic compound growth provided by an embodiment of the present invention, which specifically includes the following steps:

[0048] Step S101 , constructing 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.

[0049] In the embodiment of the present invention, the device to be predicted may be various chips or PCB circuit boards.

[0050] In the embodiment of the present invention, the structural 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 structural parameters may be the size of the upper and lower pads of the device to be predicted, the pad thickness, the bump diameter, the bump height, the bump spacing, the number of bumps, and the length, width, and height of the chip, the length, width, and height of the plastic package, and the length, width, and height of the substrate. The specific selection may be made by the technician according to the device to be predicted, and no limitation is made here.

[0051] In the embodiment of the present invention, the structural parameters of the device to be predicted can be input into finite element analysis software to achieve the construction of the finite element model. For example, the finite element analysis software can be ANSYS, Abaqus or COMSOL Multiphysics, etc.

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

[0053] In an embodiment of the present invention, based on the structural parameters of the device to be predicted, multiple finite element models can be established by setting IMC layers of multiple 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 structural parameters are exactly the same.

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

[0055] Step S102 , performing temperature cycle simulation on multiple finite element models to obtain a first relationship curve representing the change in shear plastic strain amplitude of the solder with the thickness of the IMC layer.

[0056] In the embodiment of the present invention, during the temperature cycle, high temperature will promote the growth of the IMC layer, that is, the thickness of the IMC layer will increase. The IMC layer is an intermetallic compound layer formed between the solder and the under-bump metallization layer of the chip during the welding process.

[0057] In the embodiment of the present invention, the shear plastic strain variation of the solder refers to the variation amplitude of the shear plastic strain of the solder per time period after periodic stabilization.

[0058] By performing temperature cycle simulation on multiple finite element models, a first relationship curve representing the shear plastic strain amplitude of the solder changing with the thickness of the IMC layer can be obtained.

[0059] In the embodiment of the present invention, if there is no special requirement, the temperature variation range for performing temperature cycle simulation on multiple finite element models should be selected from the national standard.

[0060] Step S103, calculating the average failure period of the solder based on the shear plastic strain amplitude of the solder, and converting the first relationship curve into a second relationship curve representing the cumulative damage of the solder in a single time period as a function of the thickness of the IMC layer according to the inverse relationship between the average failure period and the damage of the solder.

[0061] In an embodiment of the present invention, a low cycle fatigue life calculation formula, such as the Coffin-Manson model, can be used to calculate the average failure cycle of the solder based on the shear plastic strain amplitude of the solder. Among them, the Coffin-Manson model is widely used to predict the low cycle fatigue life, i.e., the average failure cycle, of a welding alloy based on the plastic strain range.

[0062] In an embodiment of the present invention, the average failure period 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 Coffin-Manson formula modified by Engelmaier (a model used to predict the fatigue life of devices under temperature cycling environment) is used to calculate the average failure cycle of the solder. The Coffin-Manson formula model incorporates parameters such as cycle frequency, that is, time cycle frequency, solder and substrate temperature into the equation.

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

[0065]

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

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

[0068]

[0069] in, represents the average solder point temperature, that is, the aforementioned substrate temperature, in °C, and f is the cycle frequency, in cycles (number of cycles) / day.

[0070] In an embodiment of the present invention, 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, that is, the first relationship curve of the plastic amplitude-IMC layer thickness can be converted into the second relationship curve of the single cycle damage of the solder-IMC layer thickness according to the low-cycle fatigue life formula while considering the inverse relationship between the damage of the solder and the average failure period.

[0071] Step S104, according to the IMC layer growth formula and multiple finite element models, a third relationship curve characterizing the change of the thickness of the IMC layer with the number of time cycles is calculated, and the third relationship curve and the second relationship curve are combined to obtain a fourth relationship curve characterizing the change of the cumulative damage of the solder in a single time period with the number of time cycles.

[0072] In the embodiment of the present invention, the IMC layer growth formula conforms to the Dybkov equation, that is, the growth thickness is directly proportional to the square root of the temperature loading time. It should be noted that the temperature loading time is the high temperature holding time in the temperature cycle.

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

[0074]

[0075] Among them, x AB represents the thickness of the IMC layer at time t; x0 represents the initial thickness of the IMC layer; C Cu represents the Cu atomic concentration in the Cu pad, and its value is 8.44×10 22 at. / cm 3 ; C Cu / SnIndicates the concentration of Cu atoms in solder, and its value is 1.1×10 20 at. / cm 3 ; represents the Cu atomic concentration in the IMC, which is 3.7×10 22 at. / cm 3 ; represents the thermal diffusion coefficient of Cu atoms in the IMC layer, The variation law with temperature T is:

[0076]

[0077] Wherein, the unit of T is ℃; The unit is cm 2 / s.

[0078] Based on this, the growth formula of the IMC layer under the corresponding temperature cycle conditions 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 cycles can be obtained according to the IMC layer growth formula.

[0079] The third relationship curve and the second relationship curve are combined to obtain a fourth relationship curve representing the variation of the cumulative damage of the solder in a single time period with the number of time periods.

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

[0081] Step S105, integrating the fourth relationship curve according to the continuous damage accumulation theory formula, when the integral sum of the accumulated damage in multiple time periods reaches 1, the multiple time periods are used as the solder fatigue life of the component to be predicted.

[0082] For life calculation under multiple stresses, Miner's fatigue cumulative damage theory believes that the fatigue damage caused by each level of stress to the material is independent of each other, and the total cumulative damage can be obtained by linearly adding the damage caused by each stress. According to Miner's fatigue cumulative damage theory, for an object with constant loading conditions, the accumulated damage D in each cycle is equal to the inverse of the fatigue life (number of time cycles), and when the total cumulative damage reaches 1, the device is judged to have failed.

[0083] For the case where the loading conditions vary with time, the cumulative damage in each time period can be found in Figure 2 , Figure 2: is a schematic diagram of the cumulative damage of the solder in a single time period provided by an embodiment of the present invention, wherein the abscissa represents the number of cycles N, that is, the number of time periods, and the ordinate represents the damage D. When the single cycle time is sufficiently small compared to the total fatigue life, the discrete damage in each time period can be regarded as Figure 2 The curve shows a function that changes continuously with time, that is, the damage in each time period can be regarded as a continuously changing process. At this time, Miner's cumulative damage theory is extended from summation to integration, and the continuous damage accumulation theory formula is obtained. Then, the fourth change curve is integrated according to the continuous damage accumulation theory formula. When the sum of the cumulative damage in multiple time periods reaches 1, that is, the integral area reaches 1, the number of multiple time periods is used as the predicted solder fatigue life of the device to be predicted, that is, the solder fatigue life considering the change in the thickness of the IMC layer is obtained at this time.

[0084] In an embodiment of the present invention, a third relationship curve characterizing the change of the thickness of the IMC layer with the number of time cycles is calculated based on the IMC layer growth formula and the finite element model of multiple IMC layers with different thicknesses, and the third relationship curve and the second relationship curve characterizing the change of the cumulative damage of the solder in a single cycle with the thickness of the IMC layer are combined to obtain a fourth relationship curve characterizing the change of the cumulative damage of the solder in a single time cycle with the number of time cycles. The fourth relationship curve is integrated according to the continuous damage accumulation theory formula. When the integral sum of the cumulative damage in multiple time cycles reaches 1, the multiple time cycles are used as the solder fatigue life of the device to be predicted. The finite element model of different IMC layer thicknesses is fitted in the time cycle through the IMC layer growth formula to achieve the purpose of simulating the continuous change of the IMC layer thickness with time, thereby realizing the prediction of solder fatigue life considering the change of IMC layer thickness, and improving the accuracy of solder fatigue life prediction.

[0085] In one implementation, a temperature cycle simulation is performed on multiple finite element models to obtain a first relationship curve representing the shear plastic strain amplitude of the solder as a function of the thickness of the IMC layer, including:

[0086] Temperature cycle simulation is performed on multiple finite element models according to a preset temperature change rate to obtain a first relationship curve representing the shear plastic strain amplitude of the solder changing with the thickness of the IMC layer; the preset temperature change rate is less than 15°C / min.

[0087] In an embodiment of the present invention, temperature cycle simulation is performed on multiple finite element models according to a preset temperature change rate, and exponential fitting is performed with the thickness of the IMC layer in the finite element model as the independent variable and the shear plastic strain amplitude of the solder in the finite element model as the dependent variable to obtain a plastic amplitude-IMC layer thickness curve, which is the first relationship curve.

[0088] Considering that most materials will experience large stress concentrations due to thermal expansion and contraction when the temperature changes rapidly, which may cause microcracks, delamination or solder joint failure. In addition, too fast a temperature change rate may introduce errors and affect the calculation results of strain and stress. Therefore, it is necessary to control the temperature change rate in the temperature cycle simulation. By setting a reasonable temperature 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 present invention, the preset temperature change rate is preferably less than 15° C. / min.

[0090] In one implementation, the continuous damage accumulation theoretical formula is determined based on the Miner fatigue accumulation damage theoretical formula;

[0091] Miner fatigue cumulative damage theory formula is:

[0092]

[0093] Where D represents the cumulative damage of 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.

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

[0095]

[0096] Among them, D 总 Indicates the integral sum of the accumulated damage over multiple time periods; 总 =1, N is equal to the average failure cycle of the solder N f ; N f D(N) represents the fourth relationship curve. 总 When ≠1, N is equal to the number of cycles for damage calculation.

[0097] Through simulation experiment examples, it is verified that the solder fatigue life prediction method considering the growth of intermetallic compounds provided by the embodiment of the present invention is nearly 30% more accurate than the existing life prediction method that does not consider the growth of the IMC layer.

[0098] Based on the same inventive concept, the embodiment of the present invention also provides a solder fatigue life prediction device considering the growth of intermetallic compounds, see Figure 3 , Figure 3: is a schematic diagram of the structure of a solder fatigue life prediction device considering the growth of intermetallic compounds provided by an embodiment of the present invention, the solder fatigue life prediction device comprising:

[0099] The finite element model building module 301 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;

[0100] A first relationship curve determination module 302 is used to perform temperature cycle simulation on multiple finite element models to obtain a first relationship curve representing the shear plastic strain amplitude of the solder as a function of the thickness of the IMC layer;

[0101] A 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 cumulative damage of the solder in a single time period as a function of the thickness of the IMC layer according to the inverse relationship between the average failure period and the damage of the solder;

[0102] A 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 cycles according to the IMC layer growth formula and multiple finite element models, and 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 cycles by combining the third relationship curve and the second relationship curve;

[0103] The solder fatigue life determination module 305 is used to integrate the fourth relationship curve according to the continuous damage accumulation theoretical formula. When the integral sum of the accumulated damage in multiple time periods reaches 1, the multiple time periods are used as the solder fatigue life of the component to be predicted.

[0104] In an embodiment of the present invention, a third relationship curve characterizing the change of the thickness of the IMC layer with the number of time cycles is calculated based on the IMC layer growth formula and the finite element model of multiple IMC layers with different thicknesses, and the third relationship curve and the second relationship curve characterizing the change of the cumulative damage of the solder in a single cycle with the thickness of the IMC layer are combined to obtain a fourth relationship curve characterizing the change of the cumulative damage of the solder in a single time cycle with the number of time cycles. The fourth relationship curve is integrated according to the continuous damage accumulation theory formula. When the integral sum of the cumulative damage in multiple time cycles reaches 1, the multiple time cycles are used as the solder fatigue life of the device to be predicted. The finite element model of different IMC layer thicknesses is fitted in the time cycle through the IMC layer growth formula to achieve the purpose of simulating the continuous change of the IMC layer thickness with time, thereby realizing the prediction of solder fatigue life considering the change of IMC layer thickness, and improving the accuracy of solder fatigue life prediction.

[0105] Optionally, the first relationship curve determination module is specifically used to perform temperature cycle simulation on the multiple finite element models according to a preset temperature change rate to obtain a first relationship curve characterizing the change in the shear plastic strain amplitude of the solder with the thickness of the IMC layer; the preset temperature change rate is less than 15°C / min.

[0106] Optionally, the second relationship curve determination module calculates the average failure period of the solder based on the shear plastic strain amplitude of the solder, including:

[0107] Based on the shear plastic strain amplitude of the solder, the average failure cycle of the solder is calculated using the Coffin-Manson formula modified by Engelmaier.

[0108] Optionally, the continuous damage accumulation theoretical formula is determined based on Miner fatigue accumulation damage theoretical formula;

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

[0110]

[0111] 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.

[0112] Optionally, the solder fatigue life determination module integrates the fourth relationship curve according to the continuous damage accumulation theory formula, including:

[0113]

[0114] Among them, D 总 represents the integral sum of the accumulated damage in the multiple time periods; 总 = 1, N is equal to the average failure cycle N of the solder f ; D(N) represents the fourth relationship curve.

[0115] It should be noted that the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present invention 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 invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention.

[0116] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. 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 invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0117] Although the present invention is described herein in conjunction with various embodiments, in the process of implementing the claimed invention, those skilled in the art can understand and implement other changes to the disclosed embodiments by viewing the drawings and the disclosed content. In the description of the present invention, the term "comprising" does not exclude other components or steps, "one" or "an" does not exclude multiple situations, and "multiple" means two or more, unless otherwise clearly and specifically limited. In addition, certain measures are recorded in different embodiments, but this does not mean that these measures cannot be combined to produce good results.

[0118] As for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0119] It should be noted that the device of the embodiment of the present invention is a device that applies the above-mentioned method for predicting solder fatigue life considering the growth of intermetallic compounds. All embodiments of the above-mentioned method for predicting solder fatigue life considering the growth of intermetallic compounds are applicable to the device and can achieve the same or similar beneficial effects.

[0120] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for predicting solder fatigue life considering intermetallic compound growth, characterized in that: The solder fatigue life prediction method comprises: Construct 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; Performing temperature cycle simulation on the multiple finite element models to obtain a first relationship curve representing a change in shear plastic strain amplitude of the solder with a change in thickness of the IMC layer; Calculating an average failure cycle of the solder based on the shear plastic strain amplitude of the solder, and converting the first relationship curve into a second relationship curve characterizing the variation 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 cycle 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 cycles is calculated according to the IMC layer growth formula and the multiple 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 cycles; The fourth relationship curve is integrated according to a continuous damage accumulation theory formula, and when the integral sum of the accumulated damage in multiple time periods reaches 1, the multiple time periods are used as the solder fatigue life of the component to be predicted.

2. The solder fatigue life prediction method according to claim 1, characterized in that: Performing temperature cycle simulation on the multiple finite element models to obtain a first relationship curve characterizing the shear plastic strain amplitude of the solder as a function of the thickness of the IMC layer, including: The multiple finite element models are subjected to temperature cycle simulation according to a preset temperature change rate to obtain a first relationship curve characterizing the shear plastic strain amplitude of the solder changing with the thickness of the IMC layer; the preset temperature change rate is less than 15°C / min.

3. The solder fatigue life prediction method according to claim 1, characterized in that: Calculating an average failure cycle of the solder based on the shear plastic strain amplitude of the solder includes: Based on the shear plastic strain amplitude of the solder, the average failure cycle of the solder is calculated using the Coffin-Manson formula modified by Engelmaier.

4. The solder fatigue life prediction method according to claim 1, characterized in that: The continuous damage accumulation theoretical formula is determined based on Miner's fatigue accumulation damage theoretical formula; The Miner fatigue cumulative damage theory formula is: 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.

5. The solder fatigue life prediction method according to claim 4, characterized in that: Integrating the fourth relationship curve according to the continuous damage accumulation theory formula includes: Among them, D 总 represents the integral sum of the accumulated damage in the multiple time periods; 总 = 1, N is equal to the average failure cycle N of the solder f ; D(N) represents the fourth relationship curve.

6. A solder fatigue life prediction device considering the growth of intermetallic compounds, characterized in that: The solder fatigue life prediction device comprises: 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; A first relationship curve determination module is used to perform temperature cycle simulation on the multiple finite element models to obtain a first relationship curve representing the shear plastic strain amplitude of the solder as a function of the thickness of the IMC layer; a second relationship curve determination module, configured to calculate an 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 characterizing the variation 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; a fourth relationship curve determination module, configured to calculate, according to the IMC layer growth formula and the plurality of finite element models, a third relationship curve characterizing the change of the thickness of the IMC layer with the number of time cycles, and to obtain, in conjunction with the third relationship curve and the second relationship curve, a fourth relationship curve characterizing the change of the cumulative damage of the solder in a single time period with the number of time cycles; The solder fatigue life determination module is used to integrate the fourth relationship curve according to the continuous damage accumulation theoretical formula. When the integral sum of the accumulated damage in multiple time periods reaches 1, the multiple time periods are used as the solder fatigue life of the component to be predicted.

7. The solder fatigue life prediction device according to claim 6, characterized in that: The first relationship curve determination module is specifically used to perform temperature cycle simulation on the multiple finite element models according to a preset temperature change rate to obtain a first relationship curve representing the shear plastic strain amplitude of the solder as a function of the thickness of the IMC layer; The preset temperature change rate is less than 15°C / min.

8. The solder fatigue life prediction device according to claim 6, characterized in that: The second relationship curve determination module calculates the average failure period of the solder based on the shear plastic strain amplitude of the solder, including: Based on the shear plastic strain amplitude of the solder, the average failure cycle of the solder is calculated using the Coffin-Manson formula modified by Engelmaier.

9. The solder fatigue life prediction device according to claim 6, characterized in that: The continuous damage accumulation theoretical formula is determined based on Miner's fatigue accumulation damage theoretical formula; The Miner fatigue cumulative damage theory formula is: 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.

10. The solder fatigue life prediction device according to claim 9, characterized in that: The solder fatigue life determination module integrates the fourth relationship curve according to the continuous damage accumulation theory formula, including: Among them, D 总 represents the integral sum of the accumulated damage in the multiple time periods; 总 = 1, N is equal to the average failure cycle N of the solder f ; D(N) represents the fourth relationship curve.

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