Hexahedral mesh generation method based on auxiliary lines
Through the hexahedral mesh generation method based on auxiliary lines, the problems of poor grid quality and difficult to control in the prior art are solved, and efficient chip thermal simulation solution and shorten simulation time are realized.
Patent Information
- Application Number
- CN202411836910.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-04-22
AI Technical Summary
The existing hexahedral mesh generation method is difficult to generate high-quality mesh in thermal simulation of 2.5D chips and 3D chips, and the mesh density is difficult to control, resulting in slow calculation speed and long simulation time.
Using the hexahedral mesh generation method based on auxiliary lines, a hexahedral mesh is generated by vertically projecting the chip's three-dimensional geometric figure into a two-dimensional projection image, partitioning auxiliary lines and discrete points are set to form a quadrilateral mesh, and stretching it to the corresponding height of the chip's three-dimensional geometric figure to generate a hexahedral mesh.
It realizes the generation of high-quality grids at the chip model boundary, and the grid density is controllable, which significantly speeds up the chip thermal simulation solution speed and shortens the thermal simulation process time.
Smart Images
Figure CN119862693A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a grid generation method, in particular to a hexahedral grid generation method based on auxiliary lines. Background Art
[0002] In the thermal simulation requirements of 2.5D chips and 3D chips, it is often necessary to establish a chip model in the thermal simulation tool based on the actual chip size. The chip model is established by generating a grid composed of several small unit grids, calculating a series of physical equations in each small unit grid, and the solver solves and analyzes a series of physical equations to obtain thermal simulation results, thereby meeting the needs of users. In the thermal simulation process, the process of generating a grid composed of several small unit grids based on the established chip model is called grid generation. After the grid is generated, the quality of each small unit grid will directly affect the calculation speed of the solver and the final calculation results. Therefore, the grid generation process plays a vital role in the thermal simulation of 2.5D chips and 3D chips.
[0003] Because of the importance of mesh generation, many methods for generating meshes of different shapes have emerged. The more famous Delaunay triangulation is a method that can generate tetrahedral meshes. In the thermal simulation requirements of 2.5D chips and 3D chips, there are nanometer-sized through holes, which are used to connect the metal traces of different chip layers. The sizes of 2.5D chips and 3D chips are in the order of millimeters, and the sizes of through holes are in the order of nanometers. In locations where the size gradient changes greatly, there will be greater stress. In order to ensure the accuracy of the subsequent solver after the solution, it is necessary to improve the convergence of the calculation results by encrypting the mesh in places with greater stress. The problem with tetrahedral meshes is that a large number of redundant tetrahedral meshes will be generated in places with greater stress, which will increase the solution time.
[0004] In recent years, some researchers have proposed hexahedral meshes. Compared with tetrahedral meshes, hexahedral meshes can reduce the generation of redundant meshes in areas with high stress, reduce the number of meshes in the overall chip model, and thus speed up the chip thermal simulation solution and shorten the thermal simulation process time.
[0005] The commonly used hexahedral mesh generation method is usually implemented based on the grid method. This method generates a grid template in advance, then superimposes the chip model to be gridded on the grid template, and fills as many regular rectangular grids or cube grids as possible inside the chip model. The shape and interconnection relationship of the hexahedral grid are changed on the boundary of the chip model according to the specific characteristics of the chip model boundary, so that the hexahedral grid on the boundary of the chip model is as close to the characteristics of the chip model boundary as possible. In the hexahedral mesh generation method based on the grid method, since the grid itself is an excellent hexahedron and is not restricted by the geometric shape, it has good geometric versatility and robustness, and has the advantages of high automation and easy solver solution. However, when the hexahedral mesh generation method based on the grid method generates a grid, the quality of the hexahedral mesh at the boundary of the chip model is poor, and the generated hexahedral mesh size is similar, and the mesh density is difficult to control, which is still difficult to meet the high-precision requirements of 2.5D chip and 3D chip thermal simulation. Summary of the invention
[0006] The technical problem to be solved by the present invention is to provide a hexahedral mesh generation method based on auxiliary lines, which can accelerate the chip thermal simulation solution speed and shorten the thermal simulation process time in 2.5D chip and 3D chip thermal simulation, and can also generate high-quality meshes on the chip model boundary and the mesh density can be controlled.
[0007] The technical solution adopted by the present invention to solve the above technical problems is: a hexahedral mesh generation method based on auxiliary lines. When using Salome chip thermal simulation software to perform thermal simulation on the chip, the three-dimensional geometric figure of the chip is first loaded, and then the three-dimensional geometric figure of the chip is vertically projected into a two-dimensional projection image. According to the density of the projection positions of each vertex of the three-dimensional geometric figure of the chip in the two-dimensional projection image, a number of partition auxiliary lines are set in the two-dimensional projection image to divide the two-dimensional projection image into a number of projection areas. Then, the same number of discrete points are set for all partition auxiliary lines, and the discrete points in corresponding positions in all partition auxiliary lines are connected to form a number of quadrilateral meshes to achieve mesh division. Finally, all quadrilateral meshes in each projection area of the two-dimensional projection image are stretched to the corresponding height of the three-dimensional geometric figure of the chip to achieve hexahedral mesh generation. These hexahedral meshes constitute a chip model.
[0008] Compared with the prior art, the present invention has the advantages that the three-dimensional geometric figure of the chip is first projected in a direction perpendicular to the direction to form a two-dimensional projection image, and the two-dimensional projection image retains the chip geometric shape information, avoiding the problem of poor mesh quality at the boundary of the chip model in the subsequent process, so that the generated mesh boundary is the boundary of the three-dimensional geometric figure of the chip. At the same time, partition auxiliary lines are set in the two-dimensional projection image based on the density of the projection positions of each vertex of the three-dimensional geometric figure of the chip in the two-dimensional projection image, and the two-dimensional projection image is divided into a number of projection areas. The density of the mesh in each projection area can be actively controlled. Compared with the hexahedral mesh generated completely based on the grid method, it has stronger density controllability. While meeting the mesh density simulation requirements, it also reduces a large number of redundant meshes, and can shorten a lot of simulation time in the thermal simulation process of the chip. In addition, the quadrilateral mesh is stretched to form a hexahedral mesh, and the quadrilateral mesh stretching process will not generate a large number of redundant meshes due to stress. Therefore, in the thermal simulation of 2.5D chips and 3D chips, the present invention can accelerate the chip thermal simulation solution speed, shorten the thermal simulation process time, and can also generate high-quality meshes at the chip model boundary, and the mesh density can be freely controlled.
[0009] Furthermore, the three-dimensional geometric figure of the chip is loaded in the following manner: a step file describing the chip geometric shape information is imported into the Salome chip thermal simulation software, and the corresponding three-dimensional geometric figure of the chip is displayed on the graphical interface of the Salome chip thermal simulation software, and the loading of the three-dimensional geometric figure of the chip is completed.
[0010] Furthermore, the specific process of vertically projecting the three-dimensional geometric figure of the chip into a two-dimensional projection image is as follows:
[0011] Step A1, projecting the three-dimensional geometric figure of the chip displayed on the graphical interface of the Salome chip thermal simulation software onto a two-dimensional plane from a viewing angle perpendicular to the top of the three-dimensional geometric figure of the chip to obtain a two-dimensional projection image of the three-dimensional geometric figure of the chip, and then displaying the two-dimensional projection image in the graphical interface of the Salome chip thermal simulation software;
[0012] Step A2: Record the projection coordinates of each vertex of the three-dimensional geometric figure of the chip in the two-dimensional projection image displayed on the graphical interface of the Salome chip thermal simulation software, that is, the projection position. At this time, a two-dimensional projection image with the projection position recorded is obtained, and the two-dimensional projection image with the projection position recorded is displayed on the graphical interface of the Salome chip thermal simulation software.
[0013] Furthermore, the shape of each partition auxiliary line extends from its center to the periphery until it intersects with the boundary of the two-dimensional projection image. After the two-dimensional projection image is divided into a number of projection areas, a two-dimensional projection image with a number of partition auxiliary lines is obtained. The two-dimensional projection image with a number of partition auxiliary lines is displayed in the two-dimensional graphical interface of the Salome chip thermal simulation software.
[0014] Furthermore, the same number of discrete points are set for all partition auxiliary lines, and the specific process of connecting the discrete points with corresponding positions in all partition auxiliary lines to form a quadrilateral mesh is as follows:
[0015] Step B1, read a python script file into the Salome chip thermal simulation software, the python script file is used to automatically set discrete points for all partition auxiliary lines in a two-dimensional projection image with a plurality of partition auxiliary lines, and the number of discrete points on each partition auxiliary line is the same, and the positions of the mth discrete points on all partition auxiliary lines are in a corresponding relationship, m = 1, 2, ..., n, n represents the number of discrete points on each partition auxiliary line;
[0016] Step B2, connecting the mth discrete points on all partition auxiliary lines in sequence, at this time forming multiple quadrilateral grids on the two-dimensional projection image with several partition auxiliary lines, and obtaining a two-dimensional projection image generating multiple quadrilateral grids, and the two-dimensional projection image generating multiple quadrilateral grids is displayed in the graphical interface of the Salome chip thermal simulation software.
[0017] Furthermore, all the quadrilateral meshes in each projection area of the two-dimensional projection image are stretched to the height corresponding to the three-dimensional geometric figure of the chip to form a hexahedral mesh. The specific process is as follows: in the Salome chip thermal simulation software, a python script for automatic stretching is read in, and all the quadrilateral meshes in each projection area in the two-dimensional projection image that generates multiple quadrilateral meshes are stretched upward to the height recorded in the step file that describes the chip geometry information. At this time, all the quadrilateral meshes in each projection area are stretched into hexahedral meshes. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 A flowchart of a method for generating a hexahedral mesh based on auxiliary lines according to the present invention;
[0019] Figure 2 This is an effect diagram of a hexahedral mesh generated by a hexahedral mesh generation method based on auxiliary lines of the present invention. DETAILED DESCRIPTION
[0020] The present invention is further described in detail below with reference to the accompanying drawings.
[0021] Embodiment 1: Figure 1 As shown, a hexahedral mesh generation method based on auxiliary lines is shown. When the chip is thermally simulated by using Salome chip thermal simulation software, the chip three-dimensional geometric figure is first loaded, and then the chip three-dimensional geometric figure is vertically projected into a two-dimensional projection image. According to the density of the projection positions of each vertex of the chip three-dimensional geometric figure in the two-dimensional projection image, a number of partition auxiliary lines are set in the two-dimensional projection image to divide the two-dimensional projection image into a number of projection areas. Then, the same number of discrete points are set for all partition auxiliary lines, and the discrete points in corresponding positions in all partition auxiliary lines are connected to form a number of quadrilateral meshes to achieve mesh division. Finally, all quadrilateral meshes in each projection area of the two-dimensional projection image are stretched to the corresponding height of the chip three-dimensional geometric figure to achieve hexahedral mesh generation. These hexahedral meshes constitute a chip model.
[0022] In this embodiment, the three-dimensional geometric figure of the chip is first projected in a direction perpendicular to it to form a two-dimensional projection image. The two-dimensional projection image can retain the chip geometric shape information, so that the mesh boundary generated subsequently is the boundary of the three-dimensional geometric figure of the chip, avoiding the problem of poor mesh quality at the boundary of the chip model. At the same time, according to the density of the projection positions of each vertex of the three-dimensional geometric figure of the chip in the two-dimensional projection image, partition auxiliary lines are set in the two-dimensional projection image, the two-dimensional projection image is divided into a number of projection areas, and the mesh density of each projection area of the two-dimensional projection image is actively controlled, so that the mesh density generated subsequently can be more consistent with the actual mesh density simulation requirements. Compared with the hexahedral mesh generated completely based on the grid method, it has stronger density controllability. While meeting the mesh density simulation requirements, it also reduces a large number of redundant meshes, which can shorten a lot of simulation time in the thermal simulation process of the chip. In addition, the hexahedral mesh generation is achieved by stretching the quadrilateral mesh to form a hexahedral mesh. The quadrilateral mesh stretching process will not generate a large number of redundant meshes due to stress.
[0023] Embodiment 2: This embodiment is basically the same as Embodiment 1, except that: in this embodiment, the three-dimensional geometric graphics of the chip are loaded in the following manner: the step file describing the chip geometric shape information is imported into the Salome chip thermal simulation software, and the corresponding three-dimensional geometric graphics of the chip are displayed on the graphical interface of the Salome chip thermal simulation software, and the loading of the three-dimensional geometric graphics of the chip is completed.
[0024] Embodiment 3: This embodiment is basically the same as Embodiment 2, except that: in this embodiment, the specific process of vertically projecting the three-dimensional geometric figure of the chip into a two-dimensional projection image is as follows:
[0025] Step A1, projecting the three-dimensional geometric figure of the chip displayed on the graphical interface of the Salome chip thermal simulation software onto a two-dimensional plane from a viewing angle perpendicular to the top of the three-dimensional geometric figure of the chip to obtain a two-dimensional projection image of the three-dimensional geometric figure of the chip, and then displaying the two-dimensional projection image in the graphical interface of the Salome chip thermal simulation software;
[0026] Step A2: Record the projection coordinates of each vertex of the three-dimensional geometric figure of the chip in the two-dimensional projection image displayed on the graphical interface of the Salome chip thermal simulation software, that is, the projection position. At this time, a two-dimensional projection image with the projection position recorded is obtained, and the two-dimensional projection image with the projection position recorded is displayed on the graphical interface of the Salome chip thermal simulation software.
[0027] In this embodiment, by recording the projection coordinates of each vertex of the chip's three-dimensional geometric figure in the two-dimensional projection image, the density of the projection positions of each vertex of the chip's three-dimensional geometric figure in the two-dimensional projection image can be displayed more intuitively, making it easier for simulation personnel to quickly set partition auxiliary lines later.
[0028] Embodiment 4: This embodiment is basically the same as Embodiment 3, except that: in this embodiment, the shape of each partition auxiliary line extends from its center to the periphery until it intersects with the boundary of the two-dimensional projection image. After the two-dimensional projection image is divided into a number of projection areas, a two-dimensional projection image with a number of partition auxiliary lines is obtained. The two-dimensional projection image with a number of partition auxiliary lines is displayed in the two-dimensional graphical interface of the Salome chip thermal simulation software.
[0029] In this embodiment, a partition auxiliary line is set by extending from the center to the periphery until it intersects with the boundary of the two-dimensional projection image, thereby ensuring that the entire area of the two-dimensional projection image is completely divided.
[0030] Embodiment 5: This embodiment is basically the same as Embodiment 4, except that: in this embodiment, the same number of discrete points are set for all partition auxiliary lines, and the specific process of connecting the discrete points in corresponding positions in all partition auxiliary lines to form a quadrilateral mesh is as follows:
[0031] Step B1, read a python script file into the Salome chip thermal simulation software, the python script file is used to automatically set discrete points for all partition auxiliary lines in a two-dimensional projection image with a plurality of partition auxiliary lines, and the number of discrete points on each partition auxiliary line is the same, and the positions of the mth discrete points on all partition auxiliary lines are in a corresponding relationship, m = 1, 2, ..., n, n represents the number of discrete points on each partition auxiliary line, and the value of n is set according to actual needs;
[0032] Step B2, connecting the mth discrete points on all partition auxiliary lines in sequence, at this time forming multiple quadrilateral grids on the two-dimensional projection image with several partition auxiliary lines, and obtaining a two-dimensional projection image generating multiple quadrilateral grids, and the two-dimensional projection image generating multiple quadrilateral grids is displayed in the graphical interface of the Salome chip thermal simulation software.
[0033] In this embodiment, after setting a number of partition auxiliary lines to divide the two-dimensional projection image into multiple projection areas, n discrete points are set for each partition auxiliary line according to actual needs. Since the number of discrete points set on each partition auxiliary line is the same, the first discrete point on the n partition auxiliary lines is connected in sequence, the second discrete point is connected in sequence, and so on, the nth discrete point is connected in sequence, thereby forming n discrete point lines, and these n discrete points and the n partition auxiliary lines are cross-linked vertically and horizontally to form multiple quadrilateral grids.
[0034] Embodiment 6: This embodiment is basically the same as Embodiment 5, except that: in this embodiment, all the quadrilateral meshes in each projection area of the two-dimensional projection image are stretched to the height corresponding to the three-dimensional geometric figure of the chip. The specific process of forming a hexahedral mesh is as follows: in the Salome chip thermal simulation software, a python script for automatic stretching is read in, and all the quadrilateral meshes in each projection area in the two-dimensional projection image that generates multiple quadrilateral meshes are stretched upward to the height recorded in the step file that describes the chip geometric shape information. At this time, all the quadrilateral meshes in each projection area are stretched into hexahedral meshes.
[0035] In this embodiment, since the two-dimensional projection image is formed by projecting from a perspective perpendicular to the top of the three-dimensional geometric figure of the chip, it retains the chip geometric shape information described in the step file that describes the chip geometric shape information. Therefore, the generated quadrilateral mesh boundary is the chip three-dimensional geometric figure boundary. After the quadrilateral mesh is stretched according to the height recorded in the step file that describes the chip geometric shape information, the generated hexahedral mesh boundary must also be the chip three-dimensional geometric figure boundary. That is, the boundary of the chip model constituted by the hexahedral mesh has a very high degree of matching with the boundary features of the chip three-dimensional geometric figure, thereby ensuring that the hexahedral mesh at the boundary of the chip model has a high quality. In addition, during the stretching process of the quadrilateral mesh, no other meshes will be generated additionally, thereby reducing a large amount of redundant mesh generation.
[0036] In order to verify the performance of the hexahedral mesh generation method based on auxiliary lines of the present invention, the hexahedral mesh generation method based on auxiliary lines of the present invention is used in the Salome chip thermal simulation software to perform a conventional thermal simulation process. In the graphical interface of the Salome chip thermal simulation software, the effect diagram of the hexahedral mesh generated by the hexahedral mesh generation method based on auxiliary lines of the present invention is obtained, as shown in FIG. Figure 2shown.
[0037] analyze Figure 2 It can be seen that: on the chip model boundary, the hexahedral mesh strictly approximates the characteristics of the chip model boundary. Figure 2 The mesh density in the middle area is significantly higher than that at the boundary. Figure 2 The partition auxiliary lines in the chip model clearly divide the chip model into several areas, and the hexahedral mesh constituting the chip model presents a regular shape. It can be seen that the effect presented by the simulation result is consistent with the effect that can be achieved by the hexahedral mesh generation method based on auxiliary lines of the present invention. The hexahedral mesh generation method based on auxiliary lines of the present invention can generate high-quality meshes at the boundaries of the chip model, and the mesh density can be controlled.
[0038] To summarize, the auxiliary line-based hexahedral mesh generation method of the present invention generates a quadrilateral mesh by two-dimensional projection, setting and removing auxiliary lines and discrete points, and connecting discrete points, and then stretching the quadrilateral mesh to form a hexahedral mesh to generate a hexahedral mesh to achieve chip modeling. Compared with the existing method of generating tetrahedral meshes based on Delaunay triangulation, it will not generate a large number of redundant meshes at places with large stress, thereby speeding up the chip thermal simulation solution speed and shortening the thermal simulation process time; compared with the existing hexahedral mesh generation method based on the grid method, the hexahedral mesh on the boundary of the chip model is as close to the characteristics of the chip model boundary as possible, the quality of the hexahedral mesh at the boundary of the chip model is significantly improved, and the mesh density can be actively controlled, which can meet the high-precision requirements of 2.5D chip and 3D chip thermal simulation.
Claims
1. A hexahedral mesh generation method based on auxiliary lines, characterized in that When using Salome chip thermal simulation software to perform thermal simulation on a chip, first load the chip's three-dimensional geometric figure, then vertically project the chip's three-dimensional geometric figure into a two-dimensional projection image, set a number of partition auxiliary lines in the two-dimensional projection image according to the density of the projection positions of the vertices of the chip's three-dimensional geometric figure in the two-dimensional projection image, and divide the two-dimensional projection image into a number of projection areas. Then, set the same number of discrete points for all partition auxiliary lines, and connect the discrete points in corresponding positions in all partition auxiliary lines to form a number of quadrilateral meshes to achieve mesh division. Finally, stretch all quadrilateral meshes in each projection area of the two-dimensional projection image to the corresponding height of the chip's three-dimensional geometric figure to achieve hexahedral mesh generation. These hexahedral meshes constitute a chip model.
2. The method for generating a hexahedral mesh based on auxiliary lines according to claim 1, characterized in that The chip three-dimensional geometric figure is loaded in the following manner: a step file describing the chip geometric shape information is imported into the Salome chip thermal simulation software, and the corresponding chip three-dimensional geometric figure is displayed on the graphical interface of the Salome chip thermal simulation software, and the chip three-dimensional geometric figure is loaded.
3. The method for generating a hexahedral mesh based on auxiliary lines according to claim 2, characterized in that The specific process of vertically projecting the chip's three-dimensional geometric figures into a two-dimensional projection image is as follows: Step A1, projecting the three-dimensional geometric figure of the chip displayed on the graphical interface of the Salome chip thermal simulation software onto a two-dimensional plane from a viewing angle perpendicular to the top of the three-dimensional geometric figure of the chip to obtain a two-dimensional projection image of the three-dimensional geometric figure of the chip, and then displaying the two-dimensional projection image in the graphical interface of the Salome chip thermal simulation software; Step A2: Record the projection coordinates of each vertex of the three-dimensional geometric figure of the chip in the two-dimensional projection image displayed on the graphical interface of the Salome chip thermal simulation software, that is, the projection position. At this time, a two-dimensional projection image with the projection position recorded is obtained, and the two-dimensional projection image with the projection position recorded is displayed on the graphical interface of the Salome chip thermal simulation software.
4. A method for generating a hexahedral mesh based on auxiliary lines according to any one of claims 1 to 3, characterized in that The shape of each partition auxiliary line is extended from the center to the periphery until it intersects with the boundary of the two-dimensional projection image. After the two-dimensional projection image is divided into several projection areas, a two-dimensional projection image with several partition auxiliary lines is obtained. The two-dimensional projection image with several partition auxiliary lines is displayed in the two-dimensional graphical interface of the Salome chip thermal simulation software.
5. The method for generating a hexahedral mesh based on auxiliary lines according to claim 4, characterized in that The same number of discrete points are set for all partition auxiliary lines, and the specific process of connecting the discrete points with corresponding positions in all partition auxiliary lines to form a quadrilateral mesh is as follows: Step B1, read a python script file into the Salome chip thermal simulation software, the python script file is used to automatically set discrete points for all partition auxiliary lines in a two-dimensional projection image with a plurality of partition auxiliary lines, and the number of discrete points on each partition auxiliary line is the same, and the positions of the mth discrete points on all partition auxiliary lines are in a corresponding relationship, m = 1, 2, ..., n, n represents the number of discrete points on each partition auxiliary line; Step B2, connecting the mth discrete points on all partition auxiliary lines in sequence, at this time forming multiple quadrilateral grids on the two-dimensional projection image with several partition auxiliary lines, and obtaining a two-dimensional projection image generating multiple quadrilateral grids, and the two-dimensional projection image generating multiple quadrilateral grids is displayed in the graphical interface of the Salome chip thermal simulation software.
6. The method for generating a hexahedral mesh based on auxiliary lines according to claim 5, characterized in that The specific process of stretching all the quadrilateral meshes in each projection area of the two-dimensional projection image to the corresponding height of the three-dimensional geometric figure of the chip to form a hexahedral mesh is as follows: in the Salome chip thermal simulation software, read the python script for automatic stretching, and stretch all the quadrilateral meshes in each projection area in the two-dimensional projection image that generates multiple quadrilateral meshes upward to the height recorded in the step file that describes the chip geometry information. At this time, all the quadrilateral meshes in each projection area are stretched into hexahedral meshes.