A method for scanning the effect of via hole position on via hole signal quality in reflow

Abstract

The present application relates to a kind of methods for scanning the influence of reflow ground via hole position on via hole signal quality, comprising the following steps: constructing the via hole structure model including signal via hole and at least one reflow ground via hole;Keep the center distance between reflow ground via hole and signal via hole constant, rotate reflow ground via hole around signal via hole center, define rotation angle as variable;Electromagnetic simulation obtains the index under different rotation angles of reflow ground via hole;Output the correlation between the different positions of reflow ground via hole and the quality index of via hole signal loss, realize the quantitative characterization of the influence of reflow ground via hole position on via hole signal quality under the condition of same center distance.The present application breaks through the limitation in traditional design method that only provides the center distance parameter of reflow ground via hole and signal via hole, and cannot quantify the influence of different positions on signal quality under the condition of same center distance, provides clear data for engineers in high-density layout scene, avoids the signal quality risk caused by blind design.

Description

Technical Field

[0001] This invention relates to the field of circuit design, and more specifically, to a method for scanning the influence of the location of return ground vias on the signal quality of vias. Background Technology

[0002] With the trend towards higher speeds and smaller sizes in electronic products, printed circuit boards (PCBs), as the core carriers for physical support and signal transmission, directly determine the overall performance stability of the equipment. This is especially true in the manufacturing process of high-speed PCBs, where via design is a critical factor affecting signal transmission integrity. To ensure effective high-speed signal transmission, simulation engineers typically define key parameters in via optimization schemes, such as the distance between signal vias, the size of anti-pad cutouts, via diameter, via pad size, and the center distance between signal vias and return ground vias. Proper matching of these parameters is fundamental to avoiding signal distortion and ensuring transmission efficiency, and is a core focus of via design within the industry.

[0003] However, existing technical solutions have significant design limitations. The optimization parameters provided by simulation engineers only specify the center-to-center distance between signal vias and return ground vias, without considering the complex requirements of actual high-density PCB layout scenarios. In designs with high wiring density, PCB engineers often employ various return ground via placement methods while maintaining a constant center-to-center distance, in order to complete via placement within a limited space. Although these placement methods all meet the center-to-center distance requirements given by simulation engineers, the impact of return ground vias in different positions on via signal quality varies.

[0004] Due to the lack of an effective method to quickly quantify the relationship between the difference in return ground via location and signal loss under the same center distance, PCB engineers can only rely on experience to select locations, resulting in a large number of blind trial and error in the design process. This not only increases the number of design iterations and reduces R&D efficiency, but may also cause quality risks such as excessive signal loss due to improper location selection. Summary of the Invention

[0005] To overcome the problem that existing technologies lack a quantitative correlation method for the difference in return ground via position and signal loss under the same center distance, resulting in low R&D efficiency and signal quality risks, this invention provides a method for scanning the influence of return ground via position on via signal quality.

[0006] The technical solution of this invention is as follows: A method for scanning the impact of via location on via signal quality includes the following steps: Step 1: Construct a via structure model that includes signal vias and at least one return ground via; Step 2: Keep the center distance between the return ground via and the signal via constant, rotate the return ground via around the center of the signal via, and define the rotation angle as a single variable; Step 3: Obtain the via signal loss quality index data corresponding to different values ​​of rotation angle within a preset range by means of electromagnetic field simulation. Step 4: Based on the data obtained in Step 3, output the correlation between different positions of the return ground via and the via signal loss quality index, so as to realize the quantitative characterization of the influence of the return ground via position on the via signal quality under the same center distance.

[0007] As a preferred embodiment of the present invention, step 2 includes: Step 201: Define the geometric center of the signal via as the rotation reference point; Step 202: Set the center distance between the return ground via and the signal via to a fixed value, and configure the return ground via at a preset initial orientation of the rotation reference point. The preset initial orientation is the starting reference for the rotation angle variable. Step 203: Set the return ground via to rotate around the rotation reference point.

[0008] As a preferred embodiment of the present invention, in the via structure model, the signal via is a differential signal via, and the number of return ground vias is two, which are symmetrically arranged on both sides of the differential signal via.

[0009] Furthermore, step 201 specifically involves defining the rotation reference point corresponding to the left return ground via as the geometric center of the left differential signal via, and the rotation reference point corresponding to the right return ground via as the geometric center of the right differential signal via. Step 202 specifically involves: the center distance between the two return ground vias and their respective corresponding differential signal vias is the fixed value, and the initial orientations of the two return ground vias are symmetrically distributed about the perpendicular bisector of the pair of differential signal vias; Step 203 specifically involves controlling the left return ground via to rotate around its rotation reference point and the right return ground via to rotate around its rotation reference point, with the two rotating in opposite directions and rotating at the same angle.

[0010] As a preferred embodiment of the present invention, the preset range of the rotation angle is -60° to 60°, and the value of the rotation angle is a discrete angle value.

[0011] Furthermore, the different values ​​of the rotation angle are distributed according to a linear step size, and the step size is set to 10° to 20°.

[0012] As a preferred embodiment of the present invention, the via signal loss quality index includes insertion loss, which is used to reflect the degree of energy attenuation of the signal during the via transmission process.

[0013] As a preferred technical solution of the present invention, the output form of the correlation between different positions of the return ground via and the via signal loss quality index includes at least one of a data table and a loss comparison curve, which is used to present the trend of the change of rotation angle and signal loss.

[0014] As a preferred technical solution of the present invention, based on the correlation between different positions of the return ground via and the signal loss quality index of the via, the method further includes step 5: calculating the signal loss margin corresponding to different rotation angles. The signal loss margin is the difference between the signal loss quality index at the current rotation angle and the minimum signal loss quality index within a preset range, which is used to quantify the performance cost of position offset on signal quality.

[0015] As a preferred embodiment of the present invention, the via structure model is a multilayer PCB model, which includes several dielectric layers, several copper layers, and via pad structure and anti-pad structure.

[0016] According to the above-described solution, the beneficial effects of this invention are as follows: This invention breaks through the limitations of traditional design methods that only provide center distance parameters for return ground vias and signal vias and cannot quantify the impact of different positions on signal quality under the same center distance. It provides PCB engineers with clear location and loss correlation data in high-density layout scenarios, avoids signal quality risks caused by blind design, and fills the gap in quantitative analysis technology for signal vias and return ground vias with the same center distance but different return ground via positions. This invention enables the rapid acquisition of signal loss data corresponding to different return ground via positions within a preset range, significantly reducing the number of design trial and error iterations; at the same time, the output correlation intuitively presents the performance change trend, helping PCB engineers quickly determine the optimal position of the return ground via and providing data support for layout decisions. Attached Figure Description

[0017] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram of the structure of the present invention; Figure 3 This is a schematic diagram of the recirculation via rotating in another direction in the model; Figure 4 The image shows a comparison of loss curves for a specific embodiment.

[0018] In the diagram, 1. Signal vias; 2. Return ground vias; 3. Anti-pad structure. Detailed Implementation

[0019] To better understand the purpose, technical solution, and technical effects of this invention, the invention will be further explained and described below in conjunction with the accompanying drawings and embodiments. It should be noted that similar reference numerals and letters in the following drawings indicate similar items; therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. It is also stated that the embodiments described below are only for explaining this invention and are not intended to limit this invention.

[0020] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is referred to as "connected to" another component, it can be directly connected to the other component or there may be an intermediate component.

[0021] The terms “first” and “second” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or specifying the number of technical features. “Several” means two or more, unless otherwise expressly and specifically defined.

[0022] like Figures 1 to 3 As shown, a method for scanning the influence of the location of a return ground via on the via signal quality includes the following steps: Step 1: Construct a via structure model that includes signal via 1 and at least one return ground via 2; The via structure model is a multilayer PCB model. In addition to signal via 1 and at least one return ground via 2, the model also includes several dielectric layers, several copper layers, via pad structure and anti-pad structure 3. The constructed via structure model can restore the real electromagnetic scene of signal transmission, ensuring that the data obtained from subsequent simulations are consistent with actual engineering applications, and avoiding analysis distortion caused by model simplification.

[0023] Step 2: Keep the center distance between the return ground via 2 and the signal via 1 constant, rotate the return ground via 2 around the center of the signal via 1, and define the rotation angle as a single variable; This step converts the positional difference of the return ground via 2 into a precisely controllable variable by fixing the center distance between the return ground via 2 and the signal via 1 and using the rotation angle.

[0024] In this embodiment, step 2 includes: Step 201: Define the geometric center of signal via 1 as the rotation reference point; The geometric center of signal via 1 is set as a unique and fixed rotation reference to ensure that all positional changes of return ground via 2 revolve around the signal transmission core. Step 202: Set the center distance between the return ground via 2 and the signal via 1 to a fixed value, and position the return ground via 2 at a preset initial orientation of the rotation reference point. The preset initial orientation is the starting reference for the rotation angle variable. This step gives the rotation angle a clear physical meaning and links the angle variable to the orientation in the PCB layout. For example, if the initial orientation of the return ground via 2 is set to the left of the signal via 1, then 0° corresponds to the direct left side of the signal via 1; 45° corresponds to the upper left of the signal via 1; and -45° corresponds to the lower left of the signal via 1. Step 203: Set the return ground via 2 to rotate around the rotation reference point; under the premise that the reference point is clear and the center distance is fixed, this step enables the position of the return ground via 2 to be flexibly switched on a circle with the signal via 1 as the center and a fixed distance as the radius through the rotation action; at the same time, the uncertain concept of "different orientations" is transformed into an adjustable rotation angle variable.

[0025] Step 3: Using electromagnetic field simulation, obtain the via signal loss quality index data corresponding to different values ​​of rotation angle within a preset range. This step accurately captures the signal transmission energy attenuation caused by the change in the position of the return ground via 2 under different rotation angles, greatly reducing the number of design trial and error iterations and avoiding the subjectivity of traditional experience judgment.

[0026] Step 4: Based on the data obtained in Step 3, output the correlation between different positions of the return ground via 2 and the via signal loss quality index, intuitively present the performance change trend, realize the quantitative characterization of the impact of the position of the return ground via 2 on the via signal quality under the same center distance, help PCB engineers quickly determine the optimal position of the return ground via 2, and provide data support for layout decisions.

[0027] For PCB engineers, in high-density PCB layouts such as mobile phone motherboards and high-speed server interfaces, when the return ground via 2 cannot be placed in an ideal position due to space constraints, there is no longer a need for guesswork placement and repeated prototyping tests. Using the method of this invention, PCB engineers can quickly obtain loss data corresponding to different positions of the return ground via 2, thereby determining whether the position of the return ground via 2 is within an acceptable range, or directly selecting the position with the least loss; avoiding signal distortion and other problems caused by improper position selection. It is evident that this invention overcomes the limitation of traditional design methods in being unable to quantify the impact of different positions of the return ground via 2 on signal quality under the same center distance, providing PCB engineers with clear position-loss correlation data in high-density layout scenarios, avoiding signal quality risks caused by blind design, and filling the gap in quantitative analysis technology for signal via 1 and return ground via 2 with the same center distance but different positions of the return ground via 2.

[0028] In this embodiment, differential signal is the mainstream signal transmission method in high-speed PCB. Therefore, the via structure is a differential signal via 1 structure. In the model, the signal via 1 is a differential signal via 1, and the number of return ground vias 2 is two, which are symmetrically arranged on both sides of the differential signal via 1.

[0029] Step 201 specifically involves defining the rotation reference point corresponding to the left return ground via 2 as the geometric center of the left differential signal via 1, and the rotation reference point corresponding to the right return ground via 2 as the geometric center of the right differential signal via 1; each differential signal via 1 has a dedicated return ground via 2, and the rotation reference point of the return ground via 2 is the center of the corresponding signal via 1. The return of the left signal is achieved through the left return ground via 2, and the return of the right signal is achieved through the right return ground via 2. Step 202 specifically involves: the center distance between the two return ground vias 2 and their respective corresponding differential signal vias 1 is a fixed value, and the initial orientation of the two return ground vias 2 is symmetrically distributed about the perpendicular bisector of the pair of differential signal vias 1. For example, the left return ground via 2 is located to the upper left of the left signal via 1, and the right return ground via 2 is located to the upper right of the right signal via 1. In the initial state, the layout on both sides is completely consistent, ensuring that the positional difference caused by rotation becomes the only variable. Step 203 specifically involves controlling the left return ground via 2 to rotate around its rotation reference point in a first direction, and the right return ground via 2 to rotate around its rotation reference point in a second direction, with the first direction and the second direction being opposite in direction, while keeping the rotation angles of the left return ground via 2 and the right return ground via 2 equal at all times; for example, the left return ground via 2 rotates counterclockwise by an angle θ, and the right return ground via 2 rotates clockwise by an angle θ, with the angles always being equal, ensuring that the symmetry of the differential signal via 1 structure remains unchanged during the rotation process.

[0030] In this embodiment, in the high-density PCB, the return ground via 2 is limited by surrounding components and wiring space, so the preset range of its rotation angle is -60° to 60° to avoid physical interference or electromagnetic interference with other devices. The rotation angle is a discrete angle value. There is no need to pursue infinite precision of continuous rotation. Only a few key discrete angles are selected. The different values ​​of the rotation angle are distributed according to a linear step size, and the step size is set to 10° to 20°. For example, the range is -60° to 60°, and the step size is 20°: -60°, -40°, -20°, 0°, 20°, 40°, 60°.

[0031] In this invention, the via signal loss quality index includes insertion loss, which reflects the degree of energy attenuation of the signal during via transmission. The output format of the correlation between different positions of the return ground via 2 and the via signal loss quality index includes at least one of a data table and a loss comparison curve, used to present the trend of change in signal loss with rotation angle.

[0032] like Figure 4 As shown in one specific embodiment, using seven different return ground via 2 positions (-60°, -40°, -20°, 0°, 20°, 40°, and 60°), a comparison chart containing seven loss curves is obtained. This clearly shows the signal loss of the signal via 1 at different rotation angles, i.e., different design positions of the return ground via 2. Through this invention, PCB engineers can better understand the signal differences when the distance between the return ground via 2 and the signal via 1 is the same but their relative positions are different. Especially in scenarios with high wiring density, where the return ground via 2 cannot be conventionally placed at the top and bottom ends of the signal via 1 and must be offset at a certain angle (such as 45 degrees or 60 degrees), PCB engineers can quickly obtain accurate data support.

[0033] In an optional embodiment, based on the correlation between different positions of the return ground via 2 and the via signal loss quality index, the method further includes step 5: calculating the signal loss margin corresponding to different rotation angles. The signal loss margin is the difference between the signal loss quality index at the current rotation angle and the minimum signal loss quality index within a preset range, used to quantify the performance cost of position offset on signal quality. Taking the aforementioned angle as an example, among all simulation data within the preset angle range of -60° to 60°, the minimum loss value is found, and the rotation angle corresponding to this minimum value is the "optimal position." For the loss value at each rotation angle, the difference between it and the minimum loss value is calculated; this difference is the signal loss margin. The size of the margin corresponds to the "degree of signal quality degradation after the position deviates from the optimal value." The smaller the margin, the lower the performance cost; the larger the margin, the higher the performance cost. The loss margin is the basis for PCB engineers to judge whether the "position offset is feasible": as long as the margin does not exceed the maximum loss threshold allowed by the project, the offset position can be selected.

[0034] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0035] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for scanning the influence of the location of a return ground via on the via signal quality, characterized in that, Includes the following steps: Step 1: Construct a via structure model that includes signal vias and at least one return ground via; Step 2: Keep the center distance between the return ground via and the signal via constant, rotate the return ground via around the center of the signal via, and define the rotation angle as a single variable; Step 3: Obtain the via signal loss quality index data corresponding to different values ​​of rotation angle within a preset range by means of electromagnetic field simulation. Step 4: Based on the data obtained in Step 3, output the correlation between different positions of the return ground via and the via signal loss quality index, so as to realize the quantitative characterization of the influence of the return ground via position on the via signal quality under the same center distance.

2. The method for scanning the influence of via location on via signal quality according to claim 1, characterized in that, Step 2 includes: Step 201: Define the geometric center of the signal via as the rotation reference point; Step 202: Set the center distance between the return ground via and the signal via to a fixed value, and configure the return ground via at a preset initial orientation of the rotation reference point. The preset initial orientation is the starting reference for the rotation angle variable. Step 203: Set the return ground via to rotate around the rotation reference point.

3. The method for scanning the influence of via location on via signal quality according to claim 2, characterized in that, In the via structure model, the signal via is a differential signal via, and there are two return ground vias, which are symmetrically arranged on both sides of the differential signal via.

4. The method for scanning the influence of via location on via signal quality according to claim 3, characterized in that, Step 201 specifically involves defining the rotation reference point corresponding to the left return ground via as the geometric center of the left differential signal via, and the rotation reference point corresponding to the right return ground via as the geometric center of the right differential signal via. Step 202 specifically involves: the center distance between the two return ground vias and their respective corresponding differential signal vias is the fixed value, and the initial orientations of the two return ground vias are symmetrically distributed about the perpendicular bisector of the pair of differential signal vias; Step 203 specifically involves controlling the left return ground via to rotate around its rotation reference point and the right return ground via to rotate around its rotation reference point, with the two rotating in opposite directions and rotating at the same angle.

5. The method for assessing the influence of via location on via signal quality according to any one of claims 1 to 4, characterized in that, The preset range of the rotation angle is -60° to 60°, and the rotation angle is a discrete angle value.

6. The method for assessing the influence of via location on via signal quality according to claim 5, characterized in that, The different values ​​of the rotation angle are distributed in a linear step size, and the step size is set from 10° to 20°.

7. The method for scanning the influence of via location on via signal quality according to claim 1, characterized in that, The signal loss quality index of vias includes insertion loss, which reflects the degree of energy attenuation of the signal during via transmission.

8. The method for scanning the influence of via location on via signal quality according to claim 1, characterized in that, The output format for the correlation between different positions of the return ground via and the via signal loss quality index includes at least one of the following: a data table and a loss comparison curve, used to present the trend of change in rotation angle and signal loss.

9. The method for assessing the influence of via location on via signal quality according to claim 1, characterized in that, Based on the correlation between different positions of the return ground via and the signal loss quality index of the via, the method also includes step 5: calculating the signal loss margin corresponding to different rotation angles. The signal loss margin is the difference between the signal loss quality index at the current rotation angle and the minimum signal loss quality index within a preset range, which is used to quantify the performance cost of position offset to signal quality.

10. The method for scanning the influence of via location on via signal quality according to claim 1, characterized in that, The via structure model is a multilayer PCB model, which includes several dielectric layers, several copper layers, and via pad structure and anti-pad structure.

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