Printed board hole site layout method

Abstract

The invention discloses a printed circuit board hole site layout method, which comprises the following steps of: 1, determining the layout state of a printed circuit board, including the size, the number of layers, the copper coating proportion, the device layout and the number of supporting points of a substrate, and establishing equivalent parameters of a printed circuit board optimization model; 2, performing grid discretization processing on the printed circuit board, and setting support point constraints and boundary conditions; 3, optimizing by adopting a particle swarm algorithm, taking the positions of the supporting points as independent particles, taking the minimum random vibration response power spectral density root-mean-square value of the key part as a target function, and obtaining a PSD root-mean-square value through discrete segmentation accumulation calculation; and step 4, performing iteration through a particle swarm algorithm to obtain an optimal hole site layout scheme. According to the method, modeling is performed on the printed circuit board, and the equivalent parameters of the printed circuit board optimization model are established, so that the layout optimization efficiency of the printed circuit board is effectively ensured.

Description

Technical Field

[0001] This invention relates to the field of hole layout in printed circuit boards, and particularly to a method for hole layout in printed circuit boards. Background Technology

[0002] The printed circuit boards (PCBs) of missile-borne electronic equipment are subjected to intense vibrations and shocks during missile flight, including engine vibration, aerodynamic loads, and separation impacts. These vibrational environments can cause structural damage to the PCBs, degrade electrical performance, and even lead to system failure. Vibration subjects the PCBs to cyclic mechanical stresses, and when the vibration frequency approaches the PCB's natural frequency, resonance occurs, resulting in amplitude amplification. Experimental data shows that when the vibration acceleration exceeds 10g, unreinforced FR-4 substrates may develop microcracks, and the inner copper foil of multilayer PCBs is prone to fatigue fracture under high-frequency vibration. Under vibration, solder joints on the PCBs can also experience fatigue fracture due to repeated stress. Simultaneously, vibration causes mechanical deformation of the PCBs, leading to changes in transmission line impedance, affecting high-speed signal quality, and high-acceleration vibrations may cause displaced or detached components that are not adequately secured.

[0003] The most effective way to improve the vibration resistance of printed circuit boards (PCBs) of missile-borne electronic equipment is to optimize the layout of PCB support points. However, most designers currently rely on experience for the layout of PCB support points. Although a few designers have used optimization algorithms to optimize the layout of support points and main components, they only consider increasing the fundamental frequency of the PCB without directly considering the magnitude of random vibration response. Summary of the Invention

[0004] The purpose of this invention is to address the issue that in the existing technology, the location of the support points to be laid out has a significant impact on the root mean square value of the power spectral density (PSD) of the random vibration response of the printed circuit board. Therefore, this invention proposes a printed circuit board hole layout method based on the root mean square value of PSD.

[0005] To achieve the above objectives, a printed circuit board hole layout method is proposed, comprising: Step 1: Determine the layout of the printed circuit board, including the size of the substrate, the number of layers, the copper coverage ratio, the device layout and the number of support points, and establish the equivalent parameters of the printed circuit board optimization model. Step 2: Discretize the printed circuit board into a mesh and set support point constraints and boundary conditions; Step 3: Optimize using particle swarm optimization, treating the support point position as an independent particle, with the objective function being to minimize the root mean square value of the random vibration response power spectral density of the key parts, and obtaining the root mean square value of PSD through discrete segmentation and accumulation calculation. Step 4: Obtain the optimal hole layout scheme through particle swarm optimization algorithm.

[0006] Optionally, among the equivalent parameters, the Poisson's ratio and elastic modulus of the printed circuit board are equivalent using the laminate theory, and the density is equivalent using the principles of consistent mass and material homogenization.

[0007] Optionally, in the boundary condition settings, constraints are applied only at the support points, and no boundary conditions are set between the support points. When multiple support points overlap, an overlapping node processing method is adopted.

[0008] Optionally, the root mean square value of the power spectral density is obtained by discretely segmenting and accumulating the power spectral density curve of the random vibration response, and the horizontal and vertical coordinates of different substrate sizes are standardized during the calculation.

[0009] Optionally, in the particle swarm optimization algorithm, the particle variable Z is represented as Z = (X1, Y1, X2, Y2, ..., X...). n Y n ), where n is the number of support points, and the dimension D=2n.

[0010] Optionally, the objective function is the average root mean square value of the power spectral density at the center point of a specified device on the printed circuit board.

[0011] Optionally, when updating the particle position, the coordinate value is calculated by adding the update velocity to the initial coordinate, and the update velocity is randomly generated between the maximum velocity and the minimum velocity.

[0012] Optionally, the particle boundary processing method is as follows: when the particle's horizontal or vertical coordinates exceed the set range, the coordinates are reset back to the boundary range in a random manner.

[0013] Optionally, the discrete segmentation and accumulation calculation uses different area calculation formulas depending on the slope of the power spectral density curve.

[0014] The advantages of this invention compared to the prior art are: (1) The present invention provides a printed circuit board hole layout method based on PSD root mean square value, which simplifies the modeling of the printed circuit board substrate and the printed circuit board with devices, and establishes the equivalent parameters of the printed circuit board optimization model, thereby effectively ensuring the efficiency of the printed circuit board optimization layout. (2) The present invention uses the position of the support point of the printed circuit board as the variable for optimizing the layout, and aims to minimize the root mean square value of the random vibration response of the key parts. The vibration response level is obtained directly to determine the vibration resistance of the printed circuit board, avoiding the indirect determination of the vibration resistance of the printed circuit board through the fundamental frequency of the printed circuit board. The former optimization method is more intuitive and accurate.

[0015] (3) The root mean square value of PSD in this invention is obtained by discretely dividing and accumulating the power spectral density curve of random vibration response. This calculation method is simple and improves the efficiency of optimization simulation.

[0016] (4) According to the vibration resistance design requirements of different parts of the printed circuit board, the present invention can obtain the hole layout scheme with the best vibration response amplification level through intelligent optimization algorithm, which avoids the empirical hole layout of the printed circuit board, reduces the complexity of vibration resistance design, and effectively improves the performance and reliability of missile-borne electronic equipment. Attached Figure Description

[0017] Figure 1 This is a flowchart of an optimized implementation scheme of the present invention; Figure 2 This is a schematic diagram of the layout of a printed circuit board. Figure 3 This is a schematic diagram of the discrete segmentation of the power spectral density curve. Detailed Implementation

[0018] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a further detailed explanation of the printed circuit board hole layout method proposed by the present invention. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, used only to facilitate and clearly illustrate the embodiments of the present invention. Please refer to the drawings to make the objectives, features, and advantages of the present invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the present invention, should still fall within the scope of the technical content disclosed in the present invention.

[0019] This invention provides a method for arranging hole positions on a printed circuit board, comprising: Step 1: Determine the layout of the printed circuit board (PCB), including the substrate size, number of layers, copper coverage ratio, component layout, and number of support points. Establish an optimization model of the PCB by determining equivalent parameters, such as equivalent density, equivalent Poisson's ratio, and equivalent elastic modulus. Specifically, the Poisson's ratio and elastic modulus of the PCB are equivalentd using laminate theory, while the density of the PCB is equivalentd using the principles of consistent mass and material homogenization.

[0020] Furthermore, the root mean square value of the power spectral density is obtained by discretely segmenting and accumulating the power spectral density curve of the random vibration response, and the horizontal and vertical coordinates of different substrate sizes are standardized during the calculation. This facilitates the updating of particle velocity and position during the optimization process and ensures the convergence of the particle swarm optimization algorithm. The discrete segmentation and accumulation calculation uses different area calculation formulas depending on the slope of the power spectral density curve.

[0021] Step 2: Discretize the printed circuit board into a mesh and select nodes within the range of support points as mounting hole constraints. This method avoids the constraint problem that the coordinates of continuous mounting holes do not coincide with the discrete nodes of the printed circuit board, and simulates the locking method of fastener support and fixation in a relatively realistic way. In addition, support point constraints and boundary conditions need to be set to ensure the rationality of the support point layout.

[0022] Furthermore, in the boundary condition settings, constraints are applied only at the support points, and no boundary conditions are set between the support points. When multiple support points overlap, an overlapping node processing method is adopted. This method ensures the rationality of the layout of all devices and support points on the substrate.

[0023] Step 3: Optimize using particle swarm optimization, treating the support point position as an independent particle, with the objective function being to minimize the root mean square value of the random vibration response power spectral density of the key parts, and obtaining the root mean square value of PSD through discrete segmentation and accumulation calculation. Step 4: Obtain the optimal hole layout scheme through particle swarm optimization algorithm.

[0024] In some embodiments, with Figure 2 Taking the printed circuit board shown as an example. Step 1: First, determine the layout of the printed circuit board, which includes 5 support points K1~K5, 2 large components C1 and C2, and also clarify the dimensions of the substrate and large components. Printed circuit boards are similar to multilayer boards, composed of stacked layers. Calculating multilayer printed circuit boards is complex, so it's necessary to directly equate the multilayer structure to a single-layer structure, which simplifies the calculation. Equivalent the multilayer printed circuit board to a single-layer board of equal thickness, and determine the equivalent parameters of the printed circuit board. In the equivalence process of Young's modulus and Poisson's ratio of the printed circuit board, the printed circuit board is assumed to be an isotropic laminate. E 1 = E 2 = E Poisson's ratio v 21 = v 12 = v Then the stiffness matrix of the laminated plate Q Represented as: Stiffness coefficient matrix of single-layer plate M Represented as: in, E For Young's modulus, t For single-layer board thickness, v It is Poisson's ratio.

[0025] To use a single-layer plate as an equivalent laminated plate, it is necessary to ensure that the front and rear stiffness coefficient matrices remain unchanged. E eff= in, E eff Equivalent Young's modulus, where t is the thickness of a single-layer plate; v eff = v PCB in, v eff For the equivalent Poisson ratio, v PCB This is the Poisson's ratio of the printed circuit board.

[0026] By utilizing the principles of consistent quality and material homogenization, we obtain in, For equivalent density, Let i be the density of the i-th layer. Let be the thickness of layer i.

[0027] For small devices with negligible dynamic characteristics, their additional effective mass is evenly distributed onto the substrate after being equivalent to a multilayer board, thus obtaining the global equivalent density; the global Young's modulus and Poisson's ratio still use the substrate parameters after being equivalent to a multilayer board.

[0028] Step 2: Determine the simulation conditions for the printed circuit board. After discretizing the printed circuit board mesh, select nodes within the mounting hole range as constraints. This approach avoids the problem of continuous mounting hole coordinates not coinciding with discrete printed circuit board nodes, while also realistically simulating the fastener locking method. Certain safety distances are set between support points and devices, between support points and substrate boundaries, and between devices and substrate boundaries. However, no boundary conditions are set between support points during optimization. When two or more support points overlap, overlapping node processing is used. These methods ensure the rationality of the layout of all devices and support points on the substrate.

[0029] Step 3: Determine the optimization method for the hole layout of the printed circuit board. In the particle swarm optimization algorithm programming, the support point positions of the printed circuit board are treated as independent particles, and the entire particle variable Z = (X1, Y1, X2, Y2, X3, Y3, X4, Y4, X5, Y5), where the dimension D is 10. That is, in the particle swarm optimization algorithm, the particle variable Z is represented as Z = (X1, Y1, X2, Y2, ..., X...). N Y N (), where N is the number of support points, and the dimension D=2N. The average root mean square value of PSD of the center points of devices C1 and C2 on the printed circuit board is used as the objective function. By minimizing the objective function, the hole layout scheme with the best vibration response amplification level for devices C1 and C2 can be obtained.

[0030] The initial N particle coordinates are randomly placed on a printed circuit board, where X... min Set the safe boundary distance a, X from the hole to the edge max Set the PCB length Xa, Y min Set the PCB width a, Y max Set to the PCB width Ya.

[0031] Implement the placement of the x and y coordinates using a programming language, randomly placing the x-coordinate at the X-axis. min and X max Between, place the vertical coordinate y randomly in Y min and Y max between.

[0032] x=rand(N,D / 2) * (X max -X min )+X min y=rand(N,D / 2) * (Y max -Y min )+Y min The x-coordinates are integrated into the odd-numbered columns of the Z matrix, and the y-coordinates are integrated into the even-numbered columns of the Z matrix.

[0033] z(:,1:2:end)=x; z(:,2:2:end)=y; The initial particle velocity is generated randomly, where V max Set to 1.5, V min Set to -1.5. The generation method is that the particle update rate v is randomly set to V. min and V max The function `rand(N,D / 2)` represents an N-row, D / 2-column matrix where the matrix elements are random numbers in the interval [0, 1].

[0034] v=rand(N,D)×(V max -V min )+V min ; v x =v(:,1:2:end); % indicates the update speed when decomposing to the horizontal coordinate; v y =v(:,2:2:end); % indicates the update speed when decomposing to the y-axis; Particle velocity and position are updated in the following ways for j=1:N v x (j,:)=w*v x (j,:)+c1*rand*(p(j,1:2:end)-x(j,:))+c2*rand*(g(1,1:2:end)-x(j,:)); x(j,:)=x(j,:)+v x (j,:); % indicates the update change of the x-axis. v y (j,:)=w*v y (j,:)+c1*rand*(p(j,2:2:end)-y(j,:))+c2*rand*(g(1,2:2:end)-y(j,:)); y(j,:)=y(j,:)+v y (j,:); % indicates the update change of the ordinate. end In the formula, v is the particle's velocity; x is the particle's current position; rand is a random number between 0 and 1; w represents the inertia weight; c1 and c2 are learning factors; p(j,:) represents the found individual optimal position; and g represents the found global optimal position.

[0035] The particle boundary is handled by setting that if the horizontal and vertical coordinates of a particle exceed the set boundary, it will be randomly placed back within the boundary. The safety distance between the aperture and the device is handled in the same way.

[0036] The following indicates that the x-axis exceeds X. max or X min If it's outside the range, pull it back.

[0037] for ii=1:D / 2 if(x(j,ii)>X max |x(j,ii) <X min ) x(j,ii)=rand*(X max -Xmin )+X min ; end The following indicates that the ordinate exceeds the Y-axis. max Or Y min If it's outside the range, pull it back.

[0038] if(y(j,ii)>Y max |y(j,ii) <Y min ) y(j,ii)=rand*(Y max -Y min )+Y min ; end end The final evolution coordinates are: z(j,1:2:end)=x(j,:); z(j,2:2:end)=y(j,:); If the length and width dimensions of a printed circuit board vary greatly, they can be standardized, that is, X max Multiply by coefficient Y max / X max Make it with Y max Keep the values ​​consistent, and then divide the x-axis by the coefficient Y in the obtained optimization results. max / X max The actual layout coordinates can be obtained, and the unified processing method ensures the convergence of the particle swarm algorithm.

[0039] Step 4: with Figure 3 Taking the power spectral density curve of random vibration response as an example, the area under the PSD curve, A1, is calculated as follows: When the slope of the random vibration response PSD curve S If the value is not -3, calculate its area using the following formula: When the slope of the random vibration response PSD curve S When the value is -3, the area is calculated using the following formula: When the slope of the random vibration response PSD curve S When the value is 0, its area is calculated using the following formula: A 2. A 3 and A Calculation reference for 4 A The root mean square value of the power spectral density of the entire random vibration response is calculated over an area.G RMS The calculation is as follows: The optimization objective is the average of the root mean square (RMS) values ​​of the PSDs at the center points of device 1 and device 2, calculated using the following formula: in: f 1 The point representing the frequency 1 on the horizontal axis. P 1 represent f 1 The power spectral density value corresponding to the point on the ordinate. f 2 The point representing the frequency 2 on the horizontal axis. P 1 represent f 1 The power spectral density value corresponding to the point on the ordinate. G RMS This is the root mean square value of the power spectral density. G RMS-C1 The root mean square value of the power spectral density of device 1 is given. G RMS-C2 is the root mean square value of the power spectral density of device 2.

[0040] By continuously changing the position of the support points, the average value of the root mean square PSD of the center points of different devices 1 and 2 can be obtained. By continuously optimizing the position of the support points of the printed circuit board through this optimization algorithm, the convergence state of the fitness value curve can be used to determine whether the optimal state has been reached. Thus, the hole layout scheme with the best vibration response amplification level of the key components of the printed circuit board can be obtained.

[0041] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0042] In the description of this invention, it should be understood that the terms "center," "height," "thickness," "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention 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, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0043] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" 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. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0044] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0045] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for arranging hole positions on a printed circuit board, characterized in that, Include: Step 1: Determine the layout of the printed circuit board, including the size of the substrate, the number of layers, the copper coverage ratio, the device layout and the number of support points, and establish the equivalent parameters of the printed circuit board optimization model. Step 2: Discretize the printed circuit board into a mesh and set support point constraints and boundary conditions; Step 3: Optimize using particle swarm optimization, treating the support point position as an independent particle, with the objective function being to minimize the root mean square value of the random vibration response power spectral density of the key parts, and obtaining the root mean square value of PSD through discrete segmentation and accumulation calculation. Step 4: Obtain the optimal hole layout scheme through particle swarm optimization algorithm.

2. The printed circuit board hole layout method as described in claim 1, characterized in that, Among the equivalent parameters, the Poisson's ratio and elastic modulus of the printed circuit board are equivalent using the laminate theory, and the density is equivalent using the principles of consistent mass and material homogenization.

3. The printed circuit board hole layout method as described in claim 1, characterized in that, In the boundary condition settings, constraints are applied only at the support points, and no boundary conditions are set between the support points. When multiple support points overlap, the overlapping node processing method is adopted.

4. The printed circuit board hole layout method as described in claim 1, characterized in that, The root mean square value of the power spectral density is obtained by discretely segmenting and summing the power spectral density curve of the random vibration response. During the calculation, the horizontal and vertical coordinates of different substrate sizes are standardized.

5. The printed circuit board hole layout method as described in claim 1, characterized in that, In the particle swarm optimization algorithm, the particle variable Z is represented as Z = (X1, Y1, X2, Y2, ..., X...). n Y n ), where n is the number of support points, and the dimension D=2n.

6. The printed circuit board hole layout method as described in claim 5, characterized in that, The objective function is the average root mean square value of the power spectral density at the center point of a specified device on the printed circuit board.

7. The printed circuit board hole layout method as described in claim 5, characterized in that, When a particle's position is updated, the coordinate value is calculated by adding the update velocity to the initial coordinate. The update velocity is randomly generated between the maximum and minimum velocities.

8. The printed circuit board hole layout method as described in claim 5, characterized in that, The particle boundary handling method is as follows: when the particle's horizontal or vertical coordinates exceed the set range, the coordinates are reset back to the boundary range in a random manner.

9. The printed circuit board hole layout method as described in claim 1, characterized in that, The discrete segmentation and accumulation calculation uses different area calculation formulas depending on the slope of the power spectral density curve.

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