Analysis of HyperMesh-based Circuit Board Assembly Methods and Hot Air Reflow Soldering Process

Abstract

This application relates to the field of computer-aided design technology, and provides a circuit board assembly method based on HyperMesh. In this method, Python is used to read information from INP format files, and then the internal scripts of the HyperMesh software are written. The circuit board assembly process is fast and convenient, and can handle the assembly of multiple components. The hot air reflow soldering process analysis method provided in this application applies the hot air reflow soldering process to the components and the entire circuit board assembled by the above-mentioned circuit board assembly method. By simulating the temperature and speed during the process, a temperature curve of the process is obtained, and the hot air reflow soldering process parameters are adjusted according to the temperature curve to improve the soldering quality.

Description

Technical Field

[0001] This invention relates to the field of computer-aided design technology, specifically to a circuit board assembly method based on hypermesh and a hot air reflow soldering process analysis method. Background Technology

[0002] To simulate the circuit board soldering process using a computer, the components and circuit board must first be assembled. Currently, the assembly of components and circuit boards requires clicking through a software interface, which is inefficient and cumbersome. Summary of the Invention

[0003] To address the problems of low efficiency and cumbersome assembly processes in existing component and circuit board assembly methods, this application provides a circuit board assembly method based on hypermesh and a hot air reflow soldering process analysis method.

[0004] The hypermesh-based circuit board assembly method includes:

[0005] S11: Establish a database of finite element mesh model INP files for various components;

[0006] S12: Select the finite element mesh model INP file of the circuit board and establish a coordinate system;

[0007] S13: Use a Python script to read the component settings information, and identify and save the component height, corresponding local coordinate system and material in the finite element mesh model INP file of the component;

[0008] S14: Use a Python script to create the preprocessing TCL script for the Hypermesh software, and rotate and move the local coordinate system of each component according to the design position;

[0009] S15: Rename the materials and local coordinate systems of different components according to the order of component reading, realize the automatic assembly of components, and output the finite element model INP file of the overall circuit board with the components assembled.

[0010] In one implementation, the database of the finite element mesh model INP file of the component contains the material information and location information of the component;

[0011] The position information of the component is based on the center of the bottom of the component as the origin of the coordinate system.

[0012] In one implementation, the coordinate system established in S12 takes the lower left corner of the plane where the top of the circuit board is located as the origin, and takes the length and width directions of the circuit board as the X and Y axes, respectively.

[0013] In one implementation, in S13, the absolute value of the difference between the maximum and minimum Z coordinate values ​​is used as the height of the component.

[0014] In one implementation, rotating and moving the local coordinate system of each component according to its designed position in step S14 includes:

[0015] Use the "rotate" function to select the origin of the component and rotate it α degrees around the Z-axis;

[0016] Use the "position" function to create six points: P1(0,0,0), P2(1,0,0), P3(0,1,0), P4(X,Y,Z), P5(X+1,Y,Z), and P6(X,Y+1,Z). Move the component from plane (P1,P2,P3) to plane (P4,P5,P6).

[0017] The hot air reflow soldering process analysis method includes obtaining a finite element model INP file of the overall circuit board with components assembled according to the circuit board assembly method described above.

[0018] In one embodiment, the hot air reflow soldering process analysis method further includes:

[0019] S21: Create the internal cavity model of the hot blast reflow oven;

[0020] S22: Select the overall INP file of the hot air reflux furnace's internal cavity model;

[0021] S23: The Python script reads the position information of the inner cavity model of the hot blast reflow oven from the overall INP file of the inner cavity model of the hot blast reflow oven.

[0022] S24: Use a Python script to create the preprocessing TCL script for the Hypermesh software. Calculate the midpoint (X1, Y1, Z1) using the maximum and minimum values ​​of the X, Y, and Z coordinates of the inner cavity model of the hot blast reflow oven. Create six points: P7(X1, Y1, Z1), P8(X1+1, Y1, Z1), P9(X1, Y1+1, Z1), P10(X2, Y2, Z2), P11(X2+1, Y2, Z2), and P12(X2, Y2+1, Z2). The plane (P10, P11, P12) represents the initial welding position of the hot blast reflow oven.

[0023] The finite element model of the entire circuit board with components is moved from plane (P7, P8, P9) to plane (P10, P11, P12) corresponding to the initial welding position of the hot air reflow oven.

[0024] S25: Generate a 2D mesh from the finite element model INP file of the overall circuit board with components. Generate the geometric outer surface of the overall circuit board model from the 2D mesh. Generate its 3D geometric solid from the geometric outer surface of the overall circuit board model. Perform Boolean operations on the geometric model of the region where the geometric solid of the overall circuit board model is located in the inner cavity model of the hot air reflow oven using the geometric solid of the overall circuit board model. Then, perform tetrahedral meshing on the region in the inner cavity model of the hot air reflow oven where Boolean operations were performed to obtain the mesh model of the inner cavity of the hot air reflow oven with the built-in finite element model of the overall circuit board with components. Output the MSH format mesh model file calculated in Fluent software.

[0025] S26: A Python script reads the information of each component and its material to obtain the process parameters for hot air reflow soldering;

[0026] S27: Generate UDF and TUI preprocessing scripts for Fluent software using Python scripts, solve them in Fluent software to obtain temperature curves, and adjust the hot air reflow soldering process parameters based on the temperature curves.

[0027] In one implementation, in S26, information about each component and its materials is read by searching for keywords.

[0028] In one implementation, in S26:

[0029] After reading the information of each component and its material, save the component's name, density, thermal conductivity, and specific heat capacity;

[0030] The obtained hot air reflow soldering process parameters include the air velocity and temperature of each temperature zone in the inner cavity model of the hot air reflow oven, as well as the speed at which the entire circuit board moves within the inner cavity model of the hot air reflow oven.

[0031] In one implementation, the UDF file defines the overall circuit board movement speed and applies it to boundary conditions, while the TUI file contains the material information of the components and applies it to the corresponding material properties of the circuit board and components.

[0032] The circuit board assembly method based on HyperMesh provided in this application uses Python to read information from INP format files and then writes the internal scripts of the HyperMesh software. The circuit board assembly process is fast and convenient and can handle the assembly of multiple components.

[0033] This application also provides a hot air reflow soldering process analysis method for the components and the entire circuit board assembled by the above-mentioned circuit board assembly method to undergo hot air reflow soldering. By simulating the temperature and speed during the process, a temperature curve of the process is obtained, and the hot air reflow soldering process parameters are adjusted according to the temperature curve to improve the soldering quality.

[0034] For further clarity, aspects and advantages of the embodiments disclosed in this application will become apparent in the following description or may be learned by practice of the embodiments disclosed in this application. Attached Figure Description

[0035] The accompanying drawings are provided to further understand this application and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation on the invention.

[0036] Figure 1 A logic flowchart of the hypermesh-based circuit board assembly method provided in Embodiment 1 of this application;

[0037] Figure 2 This is a schematic diagram of the coordinate system established in step S12 of the hypermesh-based circuit board assembly method provided in Embodiment 1 of this application;

[0038] Figure 3 This is a temperature curve obtained at two locations using the hot air reflow soldering process analysis method provided in Embodiment 2 of this application. Detailed Implementation

[0039] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0040] Example 1

[0041] This embodiment provides a circuit board assembly method based on Hypermesh, referring to... Figure 1 ,Include:

[0042] S11: Establish a database of finite element mesh model INP files for various components;

[0043] Perform some operations using scripts provided within the Hypermesh software, including:

[0044] S12: Select the finite element mesh model INP file of the circuit board being used and establish a coordinate system;

[0045] S13: Use a Python script to read the component settings information, and identify and save the component height, corresponding local coordinate system and material in the finite element mesh model INP file of the component;

[0046] S14: Use a Python script to create the preprocessing TCL script for the Hypermesh software. Rotate and move the local coordinate system of each component according to the design position; thus placing the model of each component on the circuit board model according to the design position.

[0047] S15: Rename the materials and local coordinate systems of different components according to the order of component reading, realize the automatic assembly of components, and output the finite element model INP file of the overall circuit board with the components assembled.

[0048] When assembling circuit boards using HyperMesh software, the above implementation uses Python to read information from INP format files and then writes the internal scripts of HyperMesh software. The circuit board assembly process is fast and convenient and can handle the assembly of multiple components.

[0049] In this embodiment, the database of the finite element mesh model INP file of the component contains the material information and location information of the component;

[0050] The position information of the component is based on the center of the bottom of the component as the origin of the coordinate system.

[0051] In this embodiment, the coordinate system established in S12 takes the lower left corner of the plane where the top of the circuit board is located as the origin, and the length and width directions of the circuit board as the X and Y axes, respectively. Figure 2 As shown.

[0052] Within this coordinate system, set the X-coordinate, Y-coordinate, and rotation angle α of the Z-axis around the origin for each component.

[0053] Different components in the database have different heights, and the height information of each component cannot be guaranteed during circuit board assembly. Therefore, in S13 of this embodiment, the height of the components in the finite element mesh model INP file is identified. Specifically, the information of all nodes of the component in the INP file is read by a script, and the absolute value of the difference between the maximum and minimum Z coordinates is used as the height of the component, providing a more accurate circuit board model for subsequent process analysis.

[0054] In S14 of this embodiment, rotating and moving the local coordinate system of each component according to its designed position includes:

[0055] Use the "rotate" function to select the origin of the component and rotate it α degrees around the Z-axis;

[0056] Use the "position" function to create six points: P1(0,0,0), P2(1,0,0), P3(0,1,0), P4(X,Y,Z), P5(X+1,Y,Z), and P6(X,Y+1,Z). Move the component from plane (P1,P2,P3) to plane (P4,P5,P6).

[0057] The circuit board assembled using the method provided in this embodiment can be used for subsequent hot air reflow soldering process analysis, vapor phase soldering process analysis, etc.

[0058] Example 2

[0059] This embodiment provides a hot air reflow soldering process analysis method. The circuit board model used can be obtained from the finite element model INP file of the overall circuit board with components assembled by the circuit board assembly method provided in Embodiment 1.

[0060] In this embodiment, the hot air reflow soldering process analysis method includes:

[0061] S21: Create an internal cavity model of the hot air reflow oven based on the actual hot air reflow oven in use;

[0062] S22: The internal cavity model of the hot air reflow oven can contain multiple temperature zones. In this embodiment, the internal cavity model of the hot air reflow oven can contain 10 temperature zones. Select the overall INP file of the internal cavity model of the hot air reflow oven.

[0063] S23: The Python script reads the position information of the inner cavity model of the hot blast reflow oven from the overall INP file of the inner cavity model of the hot blast reflow oven.

[0064] S24: Use a Python script to create the preprocessing TCL script for the Hypermesh software. Calculate the midpoint (X1, Y1, Z1) using the maximum and minimum values ​​of the X, Y, and Z coordinates of the inner cavity model of the hot blast reflow oven. Create six points: P7(X1, Y1, Z1), P8(X1+1, Y1, Z1), P9(X1, Y1+1, Z1), P10(X2, Y2, Z2), P11(X2+1, Y2, Z2), and P12(X2, Y2+1, Z2). The plane (P10, P11, P12) represents the initial welding position of the hot blast reflow oven.

[0065] Move the finite element model of the entire circuit board with components from plane (P7, P8, P9) to plane (P10, P11, P12) corresponding to the initial soldering position in the hot air reflow oven; specifically, the "position" function can be used to create six points: P7(X1, Y1, Z1), P8(X1+1, Y1, Z1), P9(X1, Y1+1, Z1), P10(X2, Y2, Z2), P11(X2+1, Y2, Z2), and P12(X2, Y2+1, Z2).

[0066] S25: Using the "find faces" function in TCL, generate a 2D mesh from the mesh of the overall circuit board in the finite element model INP file of the overall circuit board with components. Generate the geometric outer surface of the overall circuit board model from the 2D mesh, and then generate its 3D geometric solid from the geometric outer surface of the overall circuit board model. Perform Boolean operations on the geometric model of the region where the geometric solid of the overall circuit board model is located in the inner cavity model of the hot air reflow oven using the geometric solid of the overall circuit board model. Then, perform tetrahedral meshing on the region in the inner cavity model of the hot air reflow oven where Boolean operations were performed to obtain the mesh model of the inner cavity of the hot air reflow oven with the built-in finite element model of the overall circuit board with components. Output the MSH format mesh model file calculated in Fluent software.

[0067] In this step, while avoiding mesh overlap, a mesh model of the hot air reflow oven cavity is obtained from the finite element model of the overall circuit board with built-in components.

[0068] S26: A Python script reads the information of each component and its material to obtain the process parameters for hot air reflow soldering;

[0069] S27: Generate UDF and TUI preprocessing scripts for Fluent software using Python scripts, solve them in Fluent software, and obtain temperature profiles, such as... Figure 3 As shown, the hot air reflow soldering process parameters are adjusted according to the temperature profile. Specifically, the UDF file defines the overall circuit board movement speed and applies it to boundary conditions, while the TUI file contains component material information and applies it to the corresponding circuit board and component material properties in the MSH file.

[0070] In this embodiment, in S26, information about each component and its materials is read by searching for keywords.

[0071] In S26 of this embodiment: after reading the information of each component and its material, the name, density, thermal conductivity and specific heat capacity of the component are saved;

[0072] The obtained hot air reflow soldering process parameters include the air velocity and temperature of each of the 10 temperature zones in the inner cavity model of the hot air reflow oven, as well as the speed at which the entire circuit board moves within the inner cavity model of the hot air reflow oven, for a total of 21 parameters.

[0073] The hot air reflow soldering process analysis method provided in this embodiment obtains the temperature curve of the process by simulating the temperature and speed during the process. Based on the temperature curve, the hot air reflow soldering process parameters can be adjusted to improve the welding quality.

[0074] The simulation model for simulating the internal environment of a hot air reflux furnace can use the method described in the patent document with publication number CN116151067A.

[0075] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this technical solution and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this technical solution.

[0076] In this technical solution, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this technical solution according to the specific circumstances.

[0077] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present technical solution. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0078] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method of analyzing a hot air reflow soldering process, characterized by, Comprise: S21: create the inner cavity model of the hot air reflow oven; S22: select the INP file of the inner cavity model of the hot air reflow oven as a whole; S23: the python script reads the position information of the inner cavity model of the hot air reflow oven in the INP file of the inner cavity model of the hot air reflow oven as a whole; S24: create a pre-processing TCL script for hypermesh software using a python script, calculate the midpoint (X1, Y1, Z1) through the maximum and minimum values of the X coordinate, Y coordinate and Z coordinate of the inner cavity model of the hot air reflow oven; create six points P7 (X1, Y1, Z1), P8 (X1+1, Y1, Z1), P9 (X1, Y1+1, Z1), P10 (X2, Y2, Z2), P11 (X2+1, Y2, Z2), P12 (X2, Y2+1, Z2), wherein the plane (P10, P11, P12) is the initial welding position of the hot air reflow oven; Move the finite element model of the whole circuit board assembled with components from the plane (P7, P8, P9) to the plane (P10, P11, P12) corresponding to the initial welding position of the hot air reflow oven; S25: generate 2D grid for the grid of the whole circuit board in the finite element model INP file of the whole circuit board assembled with components, generate the geometric outer surface of the whole circuit board model through the 2D grid, then generate the 3D geometric entity of the whole circuit board model, perform Boolean operation on the geometric model of the area where the whole circuit board model is located in the inner cavity model of the hot air reflow oven, then perform tetrahedral mesh division on the area in the inner cavity model of the hot air reflow oven which has been subjected to Boolean operation, obtain the grid model of the inner cavity of the hot air reflow oven with the whole circuit board assembled with components, and output the MSH format grid model file calculated in the Fluent software; S26: the python script reads each component and its material information, and obtains the process parameters of the hot air reflow soldering; S27: generate UDF and TUI pre-processing scripts for Fluent software through python script, solve in Fluent software, obtain temperature curve, and adjust the hot air reflow soldering process parameters according to the temperature curve; Wherein, the method for obtaining the finite element model INP file of the whole circuit board assembled with components comprises: S11: establish a database of finite element grid models INP files of multiple components; S12: select the finite element grid model INP file of the circuit board, and establish a coordinate system; S13: read the setting information of the components by using the python script, identify and save the height of the components, the corresponding local coordinate system and the material in the finite element grid model INP file of the components; S14: create a pre-processing TCL script for hypermesh software using a python script, and rotate and move the local coordinate system of each component according to the design position; S15: Renaming the material and local coordinate system of different components according to the order of reading components, realizing automatic assembly of components, and outputting the finite element model INP file of the whole circuit board assembled with components.

2. The hot air reflow soldering process analysis method according to claim 1, characterized in that, In S26, the information of each component and its material is read by searching for keywords.

3. The hot air reflow soldering process analysis method according to claim 1, characterized in that, In S26: After reading the information of each component and its material, the name, density, thermal conductivity, and specific heat capacity of the component are saved. The obtained process parameters of hot air reflow soldering include the air speed and temperature of each temperature zone in the inner cavity model of the hot air reflow oven, and the moving speed of the whole circuit board in the inner cavity model of the hot air reflow oven.

4. The hot air reflow soldering process analysis method according to claim 1, characterized in that, The speed of the whole circuit board is defined in the UDF file and loaded into the boundary conditions, and the material information of the components is included in the TUI file and loaded into the material properties of the corresponding circuit board and components.

5. The hot air reflow soldering process analysis method according to claim 1, characterized in that, The database of the finite element mesh model INP file of the components includes the material information and position information of the components. The position information of the components takes the center of the bottom of the component as the coordinate origin.

6. The hot air reflow soldering process analysis method according to claim 1, characterized in that, In S12, the coordinate system is established with the lower left corner of the plane where the top of the circuit board is located as the coordinate origin, and the length and width directions of the circuit board as the X and Y axes, respectively.

7. The hot air reflow soldering process analysis method according to claim 6, characterized in that, In S13, the absolute value of the difference between the maximum and minimum values of the Z coordinate is taken as the height of the component.

8. The hot air reflow soldering process analysis method according to claim 1, characterized in that, In S14, the local coordinate system of each component is rotated and moved according to the design position, including: Using the "rotate" function, select the origin of the component and rotate it around the Z axis by α degrees. Using the "position" function, create six points P1(0, 0, 0), P2(1, 0, 0), P3(0, 1, 0), P4(X, Y, Z), P5(X+1, Y, Z), and P6(X, Y+1, Z), and move the component from the plane (P1, P2, P3) to the plane (P4, P5, P6).

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