JPH11272735A - Method for generating finite element method analysis mode for electronic device strength evaluation, method for evaluating strength of electronic device, and evaluation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for generating a finite element method analysis model for electronic device strength evaluation, an electronic device strength evaluation method and an evaluation device which evaluate an electronic device up to its fatigue life by constructing a finite element model keeping the analysis precision in a practical level in a short time independently of techniques peculiar to an analyzing operator at the time of evaluating the strength of the electronic device. SOLUTION: With respect to the finite element method analysis model, solid elements SL are used only for electronic devices in a part to be analyzed in details, and objects (electronic devices) having the same sectional shape are expressed with beam elements B. Plural objects having the same shape exist between two plane plates A and A, and plane plates A and A are expressed with shell elements S. Thus, a part to be analyzed in details can be analyzed without degrading the precision of analysis, and deformation and actions due to beam elements are caused to coincide with respect to the other part to reduce the number of elements of the entire analysis model without an influence upon the analysis precision, and therefore, the effect that thermal stress analysis in the practical level is possible is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device strength evaluation method and apparatus.

[0002]

2. Description of the Related Art When a general finite element analysis is performed, as shown in the flowchart of FIG. 15, the number of models to be examined is as follows: shape definition, characteristic definition, node creation, element creation, boundary condition setting, calculation execution The procedure of displaying the result is repeated directly by the operator. In addition, a model having an enormous number of elements is limited by the hardware environment of the computer, and requires unrealistic calculation time or cannot be executed at all.

[0003]

Normally, an operator performs all of a series of operations on a computer terminal, and the operation time is governed by the operator's unique technology. Conventionally, if there are many models to be analyzed and studied in a development procedure including simulation, the model creation time of the operator increases accordingly.

[0004] On the other hand, when a large number of elements are required for modeling, there is a problem that calculation cannot be performed due to computer restrictions. Japanese Patent Laying-Open No. 3-25957 discloses a simulation of cracks generated in an electronic device using a thermoelastic model.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to evaluate the strength of an electronic device in a short time without depending on a technique peculiar to an analysis operator. An object of the present invention is to provide a finite element method analysis model creation method for electronic device strength evaluation, an electronic device strength evaluation method, and an evaluation device capable of constructing a finite element model that maintains analysis accuracy at a level and evaluating a fatigue life.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, two opposing flat plates, a plurality of electronic devices arranged in parallel between the flat plates, and each of the electronic devices for the flat plates are provided. The finite element method analysis model used for the method of evaluating the strength of the electronic device module including the junction of the device is used. The detailed analysis part is a solid element, the two flat plates are the shell element, and the same cross-sectional shape as the solid element is based on the design parameters of the electronic device module. Is created by defining an object having a beam element.

According to a second aspect of the present invention, in the first aspect of the invention, the beam element is matched with the deformation behavior of the solid element. The invention according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the shell element is separately defined in a flat plate portion centered on a node corresponding to an intersection of the shell element and the beam element constituting the flat plate.

According to a fourth aspect of the present invention, in the third aspect, the thickness of the shell element is defined.
According to a fifth aspect of the present invention, in the third aspect, the elastic modulus of the shell element is defined. According to a sixth aspect of the present invention, in the third aspect, a plurality of shell elements are defined.

According to a seventh aspect of the present invention, in the first or second aspect, a beam element centering on a node corresponding to an intersection between the shell element and the beam element constituting the flat plate is defined. According to an eighth aspect of the present invention, in the first or second aspect, a beam element is defined for a node on a line corresponding to the outer periphery of the cross-sectional shape of the solid element in the detailed analysis portion.

According to a ninth aspect of the present invention, in the invention of the seventh or eighth aspect, the beam elements are arranged in a cross shape. According to a tenth aspect, in the seventh or eighth aspect, the arrangement of the beam elements is defined on a diagonal line. An eleventh aspect of the present invention is characterized in that in the invention of the seventh or eighth aspect, the beam elements are arranged in a leg shape.

A twelfth aspect of the present invention is characterized in that, in the seventh aspect of the invention, a sectional shape of the beam element is defined. According to a thirteenth aspect, in the seventh aspect, the elastic modulus of the beam element is defined.
According to a fourteenth aspect of the present invention, in the first or the second aspect, a solid element having a center at a node corresponding to an intersection between a shell element and a beam element constituting a flat plate is defined.

According to a fifteenth aspect of the present invention, in accordance with the fourteenth aspect, the height of the solid element is defined. According to a sixteenth aspect, in the fourteenth aspect, the elastic modulus of the solid element is defined. According to a seventeenth aspect of the present invention, in any one of the first to sixteenth aspects, the sectional shape of the solid element of the detailed analysis portion is defined and a plurality of numbers are set.

[0013] In the invention according to claim 18, a step of inputting a parameter relating to the design of the electronic device module for which the thermal stress intensity is to be evaluated, a step of calculating a temperature distribution of the electronic device module, and a step of calculating based on the parameter Item 13. A step of creating a simulation model by the finite element method analysis model creation method for electronic device strength evaluation according to any one of Items 1 to 17, and substituting the temperature distribution into a corresponding part of the simulation model to calculate heat from the temperature distribution. A stress analysis step, and a step of quantitatively evaluating the fatigue life strength of the electronic device module using the stress distribution and fatigue life data of the electronic device module obtained in the thermal stress analysis step. It is characterized by the following.

According to the nineteenth aspect, means for inputting parameters relating to the design of an electronic device module for which thermal stress intensity is to be evaluated, a function of creating a finite element analysis model based on the input parameters, and a temperature of the electronic device module Function to calculate distribution, function to calculate thermal stress with calculated temperature distribution and finite element analysis model, and comparison between thermal stress distribution obtained by thermal stress calculation and fatigue life data registered in advance in data file And a display means for displaying the data file and the analysis result obtained by the calculation means, wherein the finite element analysis model is used as the finite element analysis model. Created by the finite element method analysis model creation method for electronic device strength evaluation according to any one of 17. Characterized by using the finite element method analysis model.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the embodiments, the principle of the present invention will be described. When the finite element method is used for the strength evaluation, the finite element analysis model is composed of a solid element, a shell element, and a beam element. Generally, when performing analysis, each element is used alone, but a Peltier module, a semiconductor bump, a ball grid array (BG)
A) An electronic device module including two opposing flat plates such as a pin grid array (PGA), a plurality of electronic devices arranged in parallel between the flat plates, and a junction of each electronic device with the flat plates. In the case where a large number of objects (electronic devices) are arranged as in the above, if a finite element method analysis model is created using solid elements, the number of elements becomes enormous and calculation becomes impossible. Of course, the same applies when a large number of objects having the same shape are arranged.

As an alternative in such a case, a two-dimensional model may be analyzed for a certain cross section, but three-dimensional data cannot be obtained. Therefore, in the finite element method analysis model of the present invention, the solid element SL as shown in FIG. 1 is used only for the electronic device of the part for detailed analysis of the electronic device module M (FIG. 2 shows the appearance of the Peltier unit). , The object (electronic device) having the same cross-sectional shape as described above is represented by the beam element B. The plurality of objects having the same shape exist between the two flat plates A, A, and the flat plates A, A are represented by shell elements S.

FIG. 3A shows a solid element model.
(B) shows a beam element model, respectively. When the beam element B is used, the number of elements can be represented by a very small number as compared with a solid element model having the same cross section. However, when the shell element S and the beam element B are joined on the model, they share the same node X. However, when the model is deformed in the analysis, as shown in FIG. Load concentrates. Therefore, since the actual object has a certain cross-sectional area, the analysis corresponding to the actual phenomenon has not been performed.

A method for solving the problem will be described in detail with reference to the following embodiments. First, in order to match the deformation behavior of the solid element model shown in FIG. 5A with the deformation behavior of the beam element deformation model shown in FIG. Of the beam element B, the solid element SL
Define the same cross-sectional shape as the cross-sectional shape defined in.

Next, with respect to a node X between the beam element B and the shell element S representing the upper and lower flat plates A, A, in order to correct the joint deformation shown in FIG. Is defined as follows. That is, the beam element B is joined to the shell element S via the same node X as shown in FIG.
Define your own physical properties. Then, a new correction shell element S 'is defined around the joint node X as shown in FIG.

[0020] In the definition of the shell element S, the shell
By increasing the rigidity of element S, the concentrated load at joint X
Can be corrected. How to increase this rigidity
There is a method of increasing the thickness of the flat plate A. And other
Method to increase deformation resistance by increasing elastic modulus
Alternatively, there is a method of defining a plurality of shell elements S.

As described above, there is a method using the beam element B as a method that does not rely on correction of deformation by the shell element S.
The method of correcting the deformation by the concentrated load shown here is, of course, not defined beyond the cross section of each object. Now, in this case, the solid element SL of the detailed analysis part
8A is a method of defining a node X on a line corresponding to the outer periphery of the cross-sectional shape of FIG. 8A, a method of forming the beam element B in a cross shape as shown in FIG. 8A, and a method of forming a diagonal as shown in FIG. In particular, the diagonal method is effective because the object can define the end with respect to the rectangular cross section. As shown in FIG. 8C, there is also a method of arranging the beam element B in a leg shape diagonally from slightly above the center point.

By the way, the shear rigidity is defined as a method for matching the deformation behavior of the beam element B and the solid element SL. Here, the definition by the beam element B is used. By defining the beam element B like a tripod foot, the deformation behavior of the solid element S can be matched with that of the solid element S while considering the cross-sectional shape of the object. Under the same concept as when the shell element S is used, the definition of the cross-sectional shape of the beam element can be changed as a method of increasing the rigidity of the beam element B (for example, simply increasing the cross-sectional area). Further, the elastic modulus of the beam element B can be defined so that the beam element B has rigidity against deformation. Since the beam element B is defined between two nodes, the beam element B can be formed into a leg shape as shown in FIG.
It is easy to define a node on the outer peripheral portion of the cross-sectional shape.

Further, the beam element B and the solid element SL
There is a method using the solid element SL as a method of matching the deformation behavior of the solid element. In this case, similarly to the above two types of element definitions, a solid element SL is defined at the center of the joint node. That is, this is applied to the solid element SL as in the plate thickness (height) defined by the shell element SL. FIG. 10 shows this case. FIG. 11 shows a beam element B and a solid element SL.
And the auxiliary shell element S 'when the same load is applied to
Is shown with respect to the thickness t. In this case, it is shown that the thickness t of the auxiliary shell element S ′ in which the displacement (I) of the solid element SL matches the displacement (II) of the beam element B may be defined.

Also, the deformation behavior can be matched by a method by defining the elastic modulus. In this way, for the detailed analysis part of the finite element method analysis model, various cross-sectional shapes can be taken depending on the shape of the electronic device,
They perform detailed element division by a solid element SL at a part to be subjected to detailed analysis, and define beam elements B for many other objects, but their cross-sectional shapes are the same as those of the solid element SL. .

A method of creating a finite element method analysis model as a simulation model by the above method and evaluating the strength of an electronic device will be described based on an embodiment of an evaluation apparatus. The apparatus according to the embodiment is implemented using an electronic computer as shown in FIG. 12, and stores a keyboard 1 for inputting design parameters (specifications) of an electronic device, an arithmetic unit 2, and physical property value data. An external storage device 3,
External storage device 4 for reading and writing fatigue life data file
And a display terminal 5 for displaying the evaluation result. The strength evaluation of the electronic device module is performed according to the flowchart shown in FIG.

That is, steps (1) and (2) in FIG. 13 are design parameter processes by manual work. First, design parameters (specifications) of the electronic device module for evaluating the strength are determined. In 2), parameter input using the keyboard 1 is performed. These design parameters are parameters required for designing an electronic device module, such as the number of electronic devices, data on the arrangement of electronic devices, and the shape of electronic devices.

In this case, a screen for selecting the design parameters of the electronic device module registered in advance in the computer is displayed on the display terminal 5 connected to the computer, and the designer himself selects the design parameters while watching this display screen. And enter. After inputting the design parameters,
The arithmetic unit 2 of the electronic computer performs the following processing according to the procedure of the evaluation method programmed in advance. First, a finite element method analysis model is created as a simulation model based on the input design parameters. This step is the node creation step (3) and the element creation step (4). Here, based on the above-described method of creating the finite element method analysis model, the detailed analysis part is defined as a solid element SL,
A number of objects (electronic devices) having the same cross-sectional shape as the two flat plates A, A and the shell element S and the solid element SL are defined as beam elements B. The function of the arithmetic unit 2 corresponding to this step is the mesh data automatic generation function 20 of the FEM (finite element method analysis model) in FIG.

When performing a thermal stress analysis, it is necessary to give temperature conditions to all nodes.
It is known that a nonlinear distribution is caused by physical properties. In the embodiment of the present invention, heat generation and heat conduction are performed based on physical property value data of each part stored in the external storage device 3 based on conditions indicated by input design parameters. Is calculated to determine a temperature condition (boundary condition) (step (5)).

When this temperature condition is determined, the temperature condition is defined at each node of the finite element method analysis model in order to reflect it in the finite element method analysis model (step (6)). Then, when all the data as the finite element method analysis model have been prepared, calculation for analyzing the stress state at that time is performed (step 7). The function of the arithmetic unit 2 for performing the calculation for analysis in step (7) is a thermal stress calculation function 21 by FEM, and this step (7) is a thermal stress analysis step.

When the thermal stress analysis is obtained in this thermal stress analysis step, the maximum amplitude is calculated by the maximum stress amplitude calculating function 22 of the arithmetic unit 2 from the thermal stress analysis result (step (8)). The calculation result is compared with fatigue life data corresponding to various materials registered in the external storage device 4 in advance to determine the life cycle number of the electronic device module (product). (Step (9)). That is, this step corresponds to a step of quantitatively evaluating the life strength.

FIG. 14 shows an example of fatigue life data. The life cycle number increases as the stress amplitude decreases.
That is, it indicates that the life is prolonged. After performing the life evaluation, an analysis result (calculation result) is displayed on the display terminal 3 (step (10)). In the process corresponding to this step (10), the analysis result is post-processed, and in particular, the stress distribution of an arbitrary cross section of the solid element SL in the detailed analysis portion is displayed.

As described above, in the apparatus according to the embodiment, the steps other than the step of inputting the design parameters do not require the direct operation of the designer (operator), and the designer (operator) obtains the analysis result automatically obtained by the arithmetic unit 2. Display terminal 3
Can be easily known from the display.

[0033]

According to the first aspect of the present invention, there is provided an electronic device module comprising two opposing flat plates, a plurality of electronic devices arranged in parallel between the flat plates, and a junction of each electronic device with the flat plates. A finite element analysis model used for the strength evaluation method is created by defining a detailed analysis part from a design parameter of an electronic device module as a solid element, two flat plates as a shell element, and an object having the same cross-sectional shape as a solid element as a beam element. Therefore, many electronic devices (objects) having the same cross-sectional shape are arranged between two flat plates of the electronic device module, even if the calculation is impossible due to the limitation of the computer in the creation of the ordinary finite element method analysis model. The parts that need to be analyzed in detail can be analyzed without reducing the accuracy of the analysis. The results also have three-dimensional data, and the other parts have the same deformation behavior due to the beam elements, so that the number of elements in the entire analysis model can be reduced without affecting the analysis accuracy. Therefore, a practical level of thermal stress analysis There is an effect that it becomes possible.

According to the second aspect of the present invention, since the beam element matches the deformation behavior of the solid element, both elements can be replaced. According to the invention of claim 3, since the shell element is separately defined on the flat plate portion centered on the node corresponding to the intersection of the shell element and the beam element constituting the flat plate, the behavior at the nodal point coincides with the case where the solid element is used, There is an effect that accurate analysis can be realized.

Each of the inventions of claims 4 to 6 corresponds to claim 3
This is an embodiment of the present invention, and has the same operation and effect as the invention of claim 3. The invention of claim 7 defines a beam element centered on a node corresponding to the intersection of a shell element and a beam element constituting a flat plate, and the invention of claim 8 defines the cross-sectional shape of a solid element in a detailed analysis part. Since the beam element is defined for a node on the line corresponding to the outer periphery, the behavior at the node matches the case where a solid element is used, and there is an effect that accurate analysis can be realized.

The invention of claims 9 to 13 is the invention of claim 7
Alternatively, this is an embodiment of the invention, and has the same operation and effect as the invention of claim 7 or 8. The invention of claim 14 defines a solid element centered on a node corresponding to an intersection of a shell element and a beam element constituting a flat plate, so that the behavior at the node coincides with the case where a solid element is used for an object, There is an effect that accurate analysis can be realized.

According to the seventeenth aspect of the present invention, since the cross-sectional shape of the solid element of the detailed analysis part is defined and a plurality of numbers are set, there is no need to create a plurality of analysis models themselves, and the analysis results can be efficiently examined. Thus, finite element method analysis at a practical level can be realized. The invention according to claim 18 is a step of inputting a parameter relating to the design of an electronic device module for which thermal stress intensity is to be evaluated, a step of calculating a temperature distribution of the electronic device module, and a method based on the parameters. 17. A step of creating a simulation model by the finite element method analysis model creation method for electronic device strength evaluation according to any one of 17), and performing a thermal stress analysis from the temperature distribution by substituting the temperature distribution into a corresponding part of the simulation model. And the step of quantitatively evaluating the fatigue life strength of the electronic device module using the stress distribution and the fatigue life data of the electronic device module obtained by the thermal stress analysis step, When the parameters (specifications) are determined and the input by the designer (operator) is completed, Since the process from the creation of elementary analysis models to the calculation of fatigue life and the display of stress distribution results can be performed automatically, analysis time can be significantly reduced, and the creation of finite element method analysis models depends on the operator's unique technology. Therefore, a homogeneous finite element analysis model can always be created, and as a result, the quality of the analysis result is improved.

According to the nineteenth aspect of the present invention, it is possible to provide an apparatus capable of obtaining the effects of the eighteenth aspect.

[Brief description of the drawings]

FIG. 1 is a schematic view of a finite element method analysis model according to the present invention.

FIG. 2 is a schematic perspective view of an electronic device module to be evaluated.

FIG. 3A is a schematic view of a solid element of the finite element method analysis model according to the first embodiment. (B) is a schematic view of a beam element model of the finite element method analysis model of the above.

FIG. 4 is an explanatory diagram of deformation of a joint node between a beam element and a shell element.

FIG. 5A is a diagram showing a deformation behavior of a solid element model. (B) is a figure which shows the deformation behavior of a beam element model.

FIG. 6 is an explanatory diagram of a definition of a shell element and a beam element corresponding to deformation of a joint node between the beam element and the shell element.

FIG. 7 is an explanatory diagram of a definition of an auxiliary shell element corresponding to deformation of a joint node between a beam element and a shell element.

FIG. 8 is an explanatory diagram of a definition of a beam element corresponding to a deformation of a joint node between the beam element and the shell element.

FIG. 9 is an explanatory diagram of a definition example of a behavior match between a beam element and a solid element.

FIG. 10 is an explanatory diagram of another definition example of behavior matching between a beam element and a solid element.

FIG. 11 is a diagram illustrating a relationship between the thickness of an auxiliary shell element and the displacement of a beam element and the displacement of a solid element according to the embodiment.

FIG. 12 is a conceptual configuration diagram of an embodiment of an evaluation device of the present invention.

FIG. 13 is an operation flowchart of the above.

FIG. 14 is an explanatory diagram showing an example of fatigue life data used in the Embodiment.

FIG. 15 is a flowchart of a conventional evaluation method.

[Explanation of symbols]

 SL Solid element S Shell element B Beam element A Flat plate

[Procedure amendment]

[Submission date] November 9, 1998

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 7

[Correction method] Change

[Correction contents]

FIG. 7

Claims (19)

[Claims] 1. A finite element method used in a method for evaluating the strength of an electronic device module including two opposed flat plates, a plurality of electronic devices arranged in parallel between the flat plates, and a junction of each electronic device with the flat plate. An electronic device, wherein an analysis model is created by defining a detailed analysis part from a design parameter of an electronic device module as a solid element, two flat plates as a shell element, and an object having the same cross-sectional shape as the solid element as a beam element. A finite element method analysis model creation method for strength evaluation. 2. The method according to claim 1, wherein the beam element is matched with the deformation behavior of the solid element. 3. A finite element for evaluating the strength of an electronic device according to claim 1, wherein a shell element is separately defined on a flat plate portion centered on a node corresponding to an intersection of the shell element and the beam element constituting the flat plate. Element method analysis model creation method. 4. The method according to claim 3, wherein the thickness of the shell element is defined. 5. A method according to claim 3, wherein an elastic modulus of the shell element is defined. 6. The method according to claim 3, wherein a plurality of shell elements are defined. 7. A finite element method analysis model for electronic device strength evaluation according to claim 1, wherein a beam element centering on a node corresponding to an intersection of the shell element and the beam element constituting the flat plate is defined. How to make. 8. A finite element for evaluating the strength of an electronic device according to claim 1, wherein a beam element is defined for a node on a line corresponding to an outer periphery of a cross-sectional shape of the solid element in the detailed analysis portion. Method for creating a forensic analysis model. 9. The method according to claim 7, wherein the beam elements are arranged in a cross shape. 10. The method according to claim 7, wherein the arrangement of the beam elements is defined on a diagonal line. 11. A method according to claim 7, wherein the beam elements are arranged in a leg shape. 12. The method according to claim 7, wherein a sectional shape of the beam element is defined. 13. The method according to claim 7, wherein an elastic modulus of the beam element is defined. 14. A finite element method analysis model for electronic device strength evaluation according to claim 1, wherein a solid element centering on a node corresponding to an intersection of the shell element and the beam element constituting the flat plate is defined. How to make. 15. The method according to claim 14, wherein the height of the solid element is defined. 16. The method according to claim 14, wherein an elastic modulus of the solid element is defined. 17. The finite element method analysis model creation for electronic device strength evaluation according to claim 1, wherein a cross-sectional shape of the solid element of the detailed analysis part is defined and a plurality of numbers are set. Method. 18. A step of inputting parameters relating to the design of an electronic device module for which thermal stress intensity is to be evaluated;
Calculating the temperature distribution of the electronic device module; and generating a simulation model by the finite element method analysis model generating method for evaluating electronic device strength according to claim 1 based on the parameters. Substituting the temperature distribution into a corresponding part of the simulation model to perform a thermal stress analysis from the temperature distribution, and using the stress distribution and fatigue life data of the electronic device module obtained in the thermal stress analysis process. And quantitatively evaluating the fatigue life strength of the electronic device module. 19. A means for inputting parameters relating to the design of an electronic device module for which thermal stress intensity is to be evaluated,
A function to create a finite element analysis model with the input parameters, a function to calculate the temperature distribution of the electronic device module, a function to calculate the thermal stress using the calculated temperature distribution and the finite element analysis model, and a function to obtain the thermal stress calculation Computing means having a function of obtaining the life of the electronic device module by comparing the obtained thermal stress distribution with fatigue life data registered in advance in a data file; and the data file and analysis results obtained by the computing means. And a finite element analysis model created by the finite element analysis model creation method for electronic device strength evaluation according to any one of claims 1 to 17 as the finite element analysis model. An evaluation device, characterized in that: