Method for improving PCB (Printed Circuit Board) warping

Abstract

The invention discloses a method for improving PCB (Printed Circuit Board) bending, which effectively prevents the generation of the PCB bending problem by identifying a copper laying open area and adding a false copper PAD, and greatly saves the manpower and material resource cost and improves the production efficiency compared with the traditional post correction mode, and the addition mode of the false copper PAD is flexible and diverse, so that the production efficiency is improved. The number and the distribution can be adjusted according to the specific condition of a copper laying open area so as to achieve the optimal stress balance effect, and the copper laying device can adapt to PCBs of different shapes and sizes, has wide applicability, can be achieved only by slightly adjusting in the design stage without large-scale transformation of an existing production line, reduces the production cost, and improves the production efficiency. Due to the fact that the addition of the false copper PAD does not involve the change of the circuit function, the electrical performance of the PCB cannot be affected at all, the problem that the PCB is bent is solved, and meanwhile the stability and reliability of the PCB are guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of PCB production, and particularly relates to a method for improving PCB board warping. BACKGROUND

[0002] With the development of PCB design towards high density, high speed and high efficiency, the original design method of most parts using PTH hole plug-in assembly has been gradually eliminated, and various parts of the patch type design are used instead. The patch type parts do not have plug holes, and the flatness requirement of the PCB board is more and more strict in the SMT processing process. The conventional warping requirement (0.75% of the length of the diagonal line of the PCB) in the industry cannot meet the current production needs, and most SMT processing plants have begun to strictly control the standard.

[0003] In the prior art, the correction scheme for the warping of the PCB board is that workers correct the PCB board through a correction machine or a special plate press. Such a correction method is not only time-consuming and labor-intensive, but also extremely wasteful of cost, and is not conducive to the work in the production link. Therefore, a method for improving and solving the warping of the PCB board is urgently needed to solve the above problems. SUMMARY

[0004] In view of the deficiencies in the prior art that the warping of the PCB board is manually corrected or corrected by a plate press, resulting in time-consuming and labor-intensive and increased cost, the present application provides a method for improving the warping of the PCB board.

[0005] To achieve the above object, the present application provides a method for improving the warping of the PCB board, comprising the following steps: S1: identifying and establishing a copper-paved open area on a PCB board with completed wiring design, the copper-paved open area being an area without functional conductive patterns; S2: adding one or more than one false copper PAD in the copper-paved open area; S3: producing a PCB design file with the added false copper PAD to obtain a PCB board covered with the false copper PAD.

[0006] As an improved scheme of the present application, in step S2, when the false copper PAD is added, it is necessary to ensure that the minimum distance between the false copper PAD and the original lines and functional pads in the copper-paved open area is not less than 40 mil.

[0007] As an improved scheme of the present application, the step of adding the false copper PAD in step S2 comprises: uniformly distributing a plurality of false copper PADs in the copper-paved open area in an array form.

[0008] As an improved scheme of the present application, the shape of the false copper PAD is one or more of a circle, a square, an oval or a polygon.

[0009] As an improved scheme of the present application, the method for identifying the copper-free area in step S1 is: identifying the area with a copper coverage rate lower than a set threshold value through the copper coverage analysis function of the PCB design software.

[0010] As an improved scheme of the present application, the set threshold value is dynamically determined according to the overall average copper coverage rate of the PCB.

[0011] As an improved scheme of the present application, the false copper PAD is an electrically isolated isolated copper skin, which is not connected to any network.

[0012] As an improved scheme of the present application, in step S2, the number and total area of the added false copper PAD are determined according to the area of the copper-free area and the difference in copper coverage rate between the copper-free area and the adjacent area, so that the difference between the equivalent copper coverage rate of the area after adding the false copper PAD and the average copper coverage rate of the board falls within a preset range.

[0013] The present application has the following advantages: compared with the prior art, the present application provides a method for improving the warping of a PCB, which effectively prevents the generation of the warping problem of the PCB by identifying the copper-free area and adding a false copper PAD, greatly saving the labor and material costs compared with the traditional post-correction method, improving the production efficiency, and the adding method of the false copper PAD is flexible and diverse, and the number and distribution can be adjusted according to the specific conditions of the copper-free area to achieve the best stress balance effect, which can adapt to PCBs of different shapes and sizes, has wide applicability, does not require large-scale modification of the existing production line, and only needs slight adjustment in the design stage to achieve the purpose, thereby reducing the production cost, and since the addition of the false copper PAD does not involve changes in the circuit function, it will not have any impact on the electrical performance of the PCB, thereby solving the warping problem of the PCB while ensuring the stability and reliability of the PCB. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The process flowchart of the present application. DETAILED DESCRIPTION

[0015] In order to more clearly illustrate the present application, the present application will be further described below with reference to the accompanying drawings.

[0016] In the following description, the example details are given in order to provide a more in-depth understanding of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all embodiments. It should be understood that the specific embodiments are only used to explain the present application, and are not used to limit the present application.

[0017] It should be understood that when the terms "include" and / or "comprising" are used in the specification, they are typically used to indicate included but not to the exclusion of additional or other features, integers, steps, operations, elements, components, or groups thereof.

[0018] Referring to Figure 1 The application discloses a method for improving PCB board warping, S1: identifying and establishing a copper-paved empty area on a PCB board with completed wiring design, the copper-paved empty area being an area without functional conductive patterns; S2: adding one or more than one false copper PAD in the copper-paved empty area; S3: producing the PCB design file with the added false copper PAD to obtain a physical PCB board.

[0019] In step S1, the identification of the copper-paved empty area is a key step, which needs to accurately find the area without functional conductive patterns on the PCB board surface. These areas are usually blank areas on the PCB board, and although the blank areas do not carry any circuit structure, neither copper nor wiring, the design is the source of the board warping. Since the weight distribution on the PCB board surface is uneven, the areas without copper are prone to warping.

[0020] In step S2, the process of adding the false copper PAD needs fine operation. The designer needs to reasonably arrange the number and position of the false copper PAD according to the size and shape of the copper-paved empty area. Although the false copper PAD does not carry circuit functions, the weight of the false copper PAD can effectively balance the weight and stress distribution on the PCB board, thereby reducing the board warping phenomenon. At the same time, when the false copper PAD is added, it is necessary to ensure that the false copper PAD and the original circuit and functional pads maintain a sufficient minimum distance to avoid electrical interference or short circuit problems.

[0021] In step S3, the PCB design file added with the false copper PAD is sent to the production line, the false copper PAD is added while the PCB plate of normal standard is made according to the design file, and finally the made PCB plate has remarkable improvement in flatness; on the one hand, the present application identifies and establishes the copper laying empty area in the design stage, and adds the false copper PAD in the subsequent production, so that the plate warping problem is prevented from the source, and the waste of manpower and material resources in the subsequent correction process is avoided; on the other hand, the adding mode of the false copper PAD is flexible and various, and the number and distribution can be adjusted according to the specific situation of the copper laying empty area, so as to achieve the best stress balance effect; the present application does not need to make large-scale transformation to the existing production line, only needs to make slight adjustment in the design stage, so that the implementation cost is greatly reduced, and secondly, since the addition of the false copper PAD does not involve the change of the circuit function, the electrical performance of the PCB plate is not affected, so that the stability and reliability of the product are ensured.

[0022] In the embodiment, in step S2, when the false copper PAD is added, it is necessary to ensure that the minimum distance between the false copper PAD and the original line and functional pad in the copper laying empty area is not less than 40 mil, since the too small distance may cause short circuit between the false copper PAD and the original line or functional pad in the PCB plate processing or use process, and then affect the normal work of the whole circuit board, therefore, the minimum distance of at least 40 mil can effectively avoid the electrical interference, and can ensure that the false copper PAD plays the maximum role in balancing the stress distribution.

[0023] In the embodiment, the step of adding the false copper PAD in step S2 comprises: The plurality of false copper PADs are uniformly distributed in the copper laying empty area in an array form; by uniformly distributing the false copper PADs in the array form, the stress distribution in the copper laying empty area can be more balanced, the plate warping phenomenon caused by local stress concentration can be effectively reduced, in the design, the number of rows and columns of the array and the distance between the false copper PADs can be flexibly adjusted according to the size and shape of the copper laying empty area, so as to achieve the best stress balance effect, not only the overall structural strength of the PCB plate can be improved, but also the anti-deformation ability can be enhanced.

[0024] In this embodiment, the shape of the dummy copper PAD is one or more of the following: circular, square, elliptical, or polygonal. Since the shapes of the copper-filled empty areas vary, it is sometimes difficult to achieve the goal of balancing the weight of the PCB board by filling the empty copper-filled area with only one shape of dummy copper PAD. However, by using dummy copper PADs of various shapes, such as circular, square, elliptical, or polygonal, it is possible to more flexibly adapt to different shapes of copper-filled empty areas, achieve a more uniform stress distribution, and thus effectively reduce board warping. This not only improves the flatness of the PCB board but also enhances its structural stability and reliability. In practical applications, appropriate dummy copper PAD shapes are selected and combined according to the specific shape and size of the copper-filled empty area to achieve the best stress balance and board warping improvement effect.

[0025] In this embodiment, the method for identifying empty copper areas in step S1 is as follows: using the copper analysis function of PCB design software, areas where the copper coverage rate of the board surface is lower than a set threshold are identified.

[0026] In this embodiment, the threshold is dynamically determined based on the overall average copper coverage of the PCB board.

[0027] In this embodiment, the dummy copper PAD is an electrically isolated copper layer that is not connected to any network. Since the dummy copper PAD exists only as a structure to balance stress and does not participate in the transmission of circuit functions, setting it to an electrically isolated state can avoid interference with the original circuit, ensure the electrical performance stability of the PCB board, and effectively improve the board warping problem. The electrically isolated dummy copper PAD will not cause failure due to static electricity accumulation or other electrical factors, thus improving the overall reliability of the product.

[0028] In this embodiment, the number and total area of ​​dummy copper pads added in step S2 are determined based on the area of ​​the copper-filled empty area and the difference in copper coverage rate between it and the adjacent areas. By dynamically adjusting the amount of dummy copper pads added, the equivalent copper coverage rate of the copper-filled empty area can be made consistent with the average copper coverage rate of the board surface. By pre-determining the difference in copper coverage rate between the copper-filled empty area and the area with the circuit structure on the PCB board, the actual amount and weight of copper to be laid can be controlled in advance, thereby achieving a balance. After determining the difference in copper coverage rate, the copper coverage rate is monitored in real time by external force measuring tools such as force gauges. The copper coverage ratio is adjusted based on the actual copper-filled stress on the PCB board, which can more accurately control the stress distribution of the PCB board, thereby eliminating the stress concentration problem caused by the local low copper coverage rate.

[0029] The advantages of this invention are: 1. This invention effectively prevents PCB warping by identifying empty copper areas and adding dummy copper pads. Compared with traditional post-correction methods, it greatly saves manpower and material costs and improves production efficiency.

[0030] 2. The addition of dummy copper pads is flexible and diverse. The quantity and distribution can be adjusted according to the specific conditions of the open areas of copper plating to achieve the best stress balance effect. It can adapt to PCBs of different shapes and sizes, has wide applicability, and does not require large-scale modification of existing production lines. It can be implemented with only minor adjustments during the design stage, thus reducing production costs. 3. Since the addition of dummy copper PADs does not involve changes to the circuit function, it will not have any impact on the electrical performance of the PCB board. While solving the problem of PCB board warping, it also ensures the stability and reliability of the PCB board.

[0031] The above-disclosed embodiments are merely a few specific examples of the present invention, but the present invention is not limited thereto. Any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for improving PCB board warping, characterized in that, Includes the following steps: S1: Identify and establish open copper areas on the PCB board with completed routing design. The open copper areas are areas without functional conductive patterns. S2: Add one or more dummy copper pads to the open area of ​​the copper plating; S3: Produce the PCB design file with added fake copper pads to obtain a PCB board covered with fake copper pads.

2. The method for improving PCB board warping according to claim 1, characterized in that, In step S2, when adding the dummy copper pad, it is necessary to ensure that the minimum distance between the dummy copper pad and the original circuits and functional pads in the open area of ​​the copper pour is not less than 40 mil.

3. The method for improving PCB board warping according to claim 1, characterized in that, The step of adding a dummy copper PAD in step S2 includes: Multiple dummy copper pads are evenly distributed in an array within the open area of ​​the copper plating.

4. The method for improving PCB board warping according to claim 1, characterized in that, The shape of the fake copper PAD can be one or more of the following: round, square, oval, or polygonal.

5. The method for improving PCB board warping according to claim 1, characterized in that, The method for identifying empty copper areas in step S1 is as follows: using the copper analysis function of PCB design software, identify areas where the copper coverage rate on the board surface is lower than a set threshold.

6. The method for improving PCB board warping according to claim 5, characterized in that, The set threshold is dynamically determined based on the overall average copper plating ratio of the PCB board.

7. The method for improving PCB board warping according to claim 1, characterized in that, The dummy copper PAD is an electrically isolated copper pad that is not connected to any network.

8. The method for improving PCB board warping according to claim 1, characterized in that, In step S2, the number and total area of ​​the added dummy copper PADs are determined based on the area of ​​the copper-filled empty area and the difference in copper-filling rate between it and the adjacent area, so that the difference between the equivalent copper-filling rate of the area after addition and the average copper-filling rate of the board surface falls within a preset range.

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