A method for back drilling of PCB board and PCB board

Abstract

The application discloses a PCB back drilling processing method and a PCB, and relates to the technical field of PCB processing. The method comprises the following steps: opening a target through hole at a preset position of a PCB, performing a hole sealing and glue sticking treatment after opening a plurality of primary positioning through holes at the periphery of the PCB, and performing an electroplating process to a solder mask process; removing the glue sticking of the primary positioning through holes, calculating a theoretical coordinate of a back drilling position of the target through hole according to the position of the primary positioning through hole A, performing a first back drilling on the target through hole, and obtaining the position of a secondary positioning hole; performing a second back drilling according to the position of the secondary positioning hole, completing the back drilling processing procedure of the PCB, and effectively improving the alignment accuracy of the back drilling process of the PCB.

Description

Technical Field

[0001] This invention specifically relates to a PCB back-drilling processing method and a PCB board, belonging to the field of printed circuit board manufacturing technology. Background Technology

[0002] A PCB, also known as a printed circuit board, is the support structure for electronic components and the carrier for their electrical interconnection. In the context of the rapid development of the communications industry, high-frequency and high-speed PCBs commonly employ back-drilling designs. Back-drilling removes excess copper from metallized holes, reducing signal loss during transmission. To facilitate visual inspection of residual copper in back-drilled holes, the industry typically uses resin plugging followed by back-drilling. However, because the target holes used for back-drilling undergo subsequent processes such as resin plugging after initial drilling, issues arise such as deteriorated hole shape and resin contamination within the holes, affecting the control of back-drilling alignment. Furthermore, the coating on the positioning holes is easily peeled off, leading to issues with expansion and contraction in subsequent processes. Therefore, this process cannot completely meet the high alignment requirements of back-drilling. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a PCB back-drilling processing method and a PCB board. By utilizing the drilling equipment and the process characteristics of back-drilling depth control, the alignment accuracy of the PCB back-drilling process is improved, achieving the high precision requirement of back-drilling alignment.

[0004] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0005] A method for back drilling of a PCB board is provided, the method comprising:

[0006] A target through-hole is opened at a preset position on the PCB board, and several primary positioning through-holes are opened on the periphery of the PCB board.

[0007] The primary positioning through hole is sealed with adhesive, and the target through hole is electroplated to the solder resist process; the adhesive on the primary positioning through hole is removed, and the theoretical coordinates of the back drill position of the target through hole are calculated based on the position of the primary positioning through hole.

[0008] The target through hole is back-drilled for the first time according to the theoretical coordinates of the target through hole back-drilling position to obtain the position of the secondary positioning hole; the diameter of the first back-drilling is 3-4 mil larger than the diameter of the theoretical coordinates, and the depth of the first back-drilling is less than 15 mil.

[0009] The second back drilling is performed based on the position of the secondary positioning hole to complete the PCB back drilling process; the depth of the second back drilling is greater than the depth of the first back drilling.

[0010] Furthermore, the primary positioning through hole is sealed with adhesive before the resin plugging process to prevent it from being blocked by resin.

[0011] Furthermore, the secondary positioning holes are located near the four corners of the PCB perimeter or near the center of the long and short sides.

[0012] Furthermore, the primary positioning through hole and the back drill bottom hole are drilled together, and the secondary positioning hole is part of the bottom hole of the back drill bottom hole. The coordinates of the secondary positioning hole are the same as the coordinates of the back drill bottom hole.

[0013] Furthermore, the cover plate used for the first and second back drilling was a single-sided aluminum foil, and the cover plate was replaced after the first back drilling was completed.

[0014] The present invention also provides a PCB board, which is manufactured according to the processing method described in any of the preceding claims.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0016] The present invention provides a method for back drilling after resin plugging, which effectively solves the target hole quality problem caused by process design by back drilling twice, and improves the back drilling alignment to within 3mil. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the PCB back drilling processing method provided in an embodiment of the present invention;

[0018] Figure 2 The diagram illustrates the structural principle of an embodiment of the present invention. Detailed Implementation

[0019] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments and specific features in the embodiments are detailed descriptions of the technical solution of the present application, rather than limitations thereof. In the absence of conflict, the embodiments and technical features in the embodiments can be combined with each other.

[0020] In this document, the term "and / or" merely describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " generally indicates that the preceding and following related objects have an "or" relationship. To better understand the technical content of this invention, the technical solution of this invention will be further introduced and explained below with reference to specific implementation examples.

[0021] This invention provides a method for back drilling of PCB boards, specifically relating to an alignment method for back drilling after resin plugging, comprising:

[0022] A target through-hole is opened at a preset position on the PCB board, and several primary positioning through-holes are opened on the periphery of the PCB board.

[0023] The primary positioning through hole is sealed with adhesive, and the target through hole is electroplated and then subjected to the anti-welding process.

[0024] Remove the adhesive from the primary positioning through hole, and calculate the theoretical coordinates of the target through hole back drill position based on the position of the primary positioning through hole A;

[0025] The target through hole is back-drilled for the first time according to the theoretical coordinates of the target through hole back-drilling position to obtain the position of the secondary positioning hole; the diameter of the first back-drilling is 3-4 mil larger than the diameter of the theoretical coordinates, and the depth of the first back-drilling is less than 15 mil.

[0026] The second back drilling is performed based on the position of the secondary positioning hole to complete the PCB back drilling process; the depth of the second back drilling is greater than the depth of the first back drilling.

[0027] The specific steps are as follows:

[0028] Target through-holes are drilled at predetermined locations on the PCB board. Several primary positioning through-holes are drilled around the perimeter of the PCB board; specifically, a dedicated target hole A for back-drilling is designed on the outside of the PCB board, serving as the primary positioning hole. Target hole A is drilled during the first drilling operation, simultaneously with the initial back-drilling hole. After the first drilling is completed, the target through-holes undergo normal processing steps such as plating, resin plugging, outer layer patterning, and solder masking, before proceeding to the back-drilling process. Figure 1 The process is shown below.

[0029] One of the drills needs to drill the target hole A used for back drilling. The target hole A is designed on the periphery of the PCB and does not pass through the resin plug. The target hole A needs to be covered with tape during the resin plugging process to prevent it from being blocked by resin.

[0030] like Figure 2 The diagram shown is a structural principle diagram provided in an embodiment of the present invention. The back drilling process is divided into two back drilling operations. The theoretical coordinates of the target through-hole back drilling position are calculated based on the position of the first positioning through-hole A. The target through-hole is then back drilled for the first time based on the theoretical coordinates of the target through-hole back drilling position. The first back drilling uses a CCD drill to grasp the target hole A outside the board, controlling the depth D < 15mil, and drilling several back drilling holes H near the four corners of the PCB periphery or near the center of the long and short sides. The back drilling holes H must satisfy the requirement that the drilling depth is greater than the control depth D.

[0031] The second back drilling uses a CCD drill to capture several target holes A1, i.e., secondary positioning holes, and controls the depth D1 (D1>D) to drill all the holes, thus completing the back drilling.

[0032] Furthermore, during the first back-drilling, the depth D is controlled to be a shallow hole, less than 15mil. The purpose is to control the depth to create a window, remove the surface ink and resin, and expose hole A1, making it easier for the CCD to grasp during the second back-drilling. The back-drilled hole H from the first back-drilling should be selected from the back-drilled holes near the four corners of the PCB or near the center of the long and short sides.

[0033] During the second back drilling, the target hole A1 that was grabbed was drilled out in the first drill, which is the bottom hole corresponding to the back drilling. Its coordinates are the same as those of hole H. The diameter of the back drilling hole H is greater than the diameter of the target hole A1.

[0034] The second back-drilling control depth D1 is the depth to which the finished product needs to be drilled, and D1 must be greater than D.

[0035] Preferably, the order of the first and second back drilling cannot be changed. The cover plate used for both back drillings is single-sided aluminum foil. The cover plate needs to be replaced after the first back drilling is completed, and the cover plate must be put on after the second back drilling is completed.

[0036] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0037] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A PCB back drilling method characterized by, The method comprises: A target through hole is formed at a preset position of the PCB, and a plurality of primary positioning through holes are formed at the periphery of the PCB; The primary positioning through holes are subjected to hole sealing and glue sticking treatment, and the target through hole is subjected to electroplating, resin hole plugging, outer layer pattern making and solder mask treatment; The glue sticking of the primary positioning through holes is removed, and the theoretical coordinates of the back drilling position of the target through hole are calculated according to the position of the primary positioning through holes; The target through hole is subjected to first back drilling according to the theoretical coordinates of the back drilling position of the target through hole, a plurality of secondary positioning holes are formed at the preset position, the primary positioning through holes and the back drilling bottom hole are drilled together, the secondary positioning holes are part of the back drilling bottom hole, the coordinates of the secondary positioning holes are the same as the back drilling coordinates, the diameter of the first back drilling is 3-4 mil larger than the diameter of the theoretical coordinates, and the first back drilling depth is less than 15 mil; Second back drilling is performed according to the position of the secondary positioning holes, and the back drilling process of the PCB is completed; the second back drilling depth is greater than the first back drilling depth.

2. The method of claim 1, wherein: The primary positioning through holes are subjected to hole sealing and glue sticking treatment before the resin hole plugging process.

3. The method of claim 1, wherein: The secondary positioning holes are close to the four corners of the periphery of the PCB or close to the center position of the long and short sides.

4. The method of claim 1 wherein: The cover plate used for the first back drilling and the second back drilling is single-sided aluminum foil, and the cover plate is replaced after the first back drilling is completed.

5. A PCB board characterized by: The processing method is prepared according to any one of claims 1-4.

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