A kind of transverse compensation processing method and PCB plate of through-hole back drilling

Abstract

This invention relates to the field of PCB board technology, specifically to a lateral compensation processing method for back-drilling interconnected holes and a PCB board. The processing method includes the following steps: S1, fabricating a lamination board, drilling holes in the lamination board to obtain through holes, forming a copper layer on the hole wall of the through holes, and electroplating the copper layer on the hole wall with tin; S2, first back-drilling the first conductive hole to obtain a first back-drilled hole, and then back-drilling the second conductive hole to obtain a second back-drilled hole; S3, drilling connecting grooves at adjacent positions of the first and second back-drilled holes to connect the first and second back-drilled holes, completing the back-drilling; S4, performing micro-etching on the lamination board after back-drilling to remove back-drilled copper slag and burrs from the hole openings, and then performing a tin stripping process on the tin layer inside the conductive holes; S5, simultaneously filling the first and second back-drilled holes with resin, drying and curing the resin, and then grinding the resin overflowing from the hole openings.

Description

Technical Field

[0001] This invention relates to the field of PCB technology, specifically to a lateral compensation processing method for back-drilling of interconnected holes and a PCB. Background Technology

[0002] With the rapid development and widespread application of new technologies such as 5G, ABC (AI, Big Data, Cloud Computing), and IoT, printed circuit boards (PCBs) suitable for high-frequency communication and phased array radar are evolving towards higher density, higher precision, higher integration, and multi-layering. PCBs for high-frequency communication and radar antennas need to meet the requirements of high-integrity electronic signal transmission. Back drilling, a technique that removes excess pillars affecting the signal path from the reverse side, can improve the electronic signal transmission functionality. The back drilling process is described in [link to back drilling process]. Figure 1 .

[0003] To ensure complete removal of copper from signal path vias, back-drilling often requires a larger drill bit diameter. When two signal paths are close together (spacing ≤ 0.3mm), the back-drill diameter can reach up to 0.5mm to maximize copper removal. In practice, when drilling adjacent conductive vias that are close to each other, one via needs to be back-drilled first, followed by the other. This presents the following problems: Because the two vias are close together, the thickness of the board material between adjacent vias is further reduced after back-drilling one via. When back-drilling the other via, the drill bit will tilt towards the side with less board material, resulting in low verticality and a distorted drill hole. Ultimately, when resin is applied to the drill hole, the resin cannot adhere evenly to the distorted hole wall, significantly affecting the quality of the PCB board. Summary of the Invention

[0004] One of the objectives of this invention is to provide a lateral compensation machining method for back drilling of connected holes, which avoids the shortcomings of the prior art. This lateral compensation machining method for back drilling of connected holes can efficiently and accurately back drill close electrical signal channels, effectively avoiding the problems of through hole damage and through hole channel offset, and improving the accuracy of back drilling.

[0005] The second objective of this invention is to provide a PCB board.

[0006] To achieve one of the above objectives, the present invention provides the following technical solution:

[0007] A lateral compensation machining method for consecutive back-drilled holes is provided, which includes the following steps when it is necessary to create adjacent back-drilled holes:

[0008] S1. Fabricate a pressing plate, drill holes in the pressing plate to obtain through holes, fabricate a copper layer on the hole wall of the through holes, and electroplate the copper layer on the hole wall with tin so that the copper layer on the hole wall of the conductive hole is plated with a tin layer.

[0009] S2. First, perform a first back drill on the first conductive hole to obtain a first back drill hole, and then perform a second back drill on the second conductive hole to obtain a second back drill hole.

[0010] S3. Drill a connecting groove at the adjacent positions of the first back drill hole and the second back drill hole to connect the first back drill hole and the second back drill hole, thus completing the back drilling.

[0011] S4. Perform micro-etching on the back-drilled laminate to remove the back-drilled copper slag and burrs from the hole opening, and then perform tin stripping on the laminate.

[0012] S5. Simultaneously, the first back drill hole and the second back drill hole are filled with resin, the resin is dried and cured, and then the resin overflowing from the hole is ground.

[0013] In some embodiments, the manufacturing steps of the pressing plate include:

[0014] S11. Cut the core board by stacking the core board into a copper-clad laminate and cutting the copper-clad laminate.

[0015] S12. Apply a film to the copper-clad laminate and expose it to transfer the preset circuit pattern to the corresponding copper-clad laminate. Etch the copper-clad laminate to produce a core board containing the circuit pattern.

[0016] S13. Stack all core boards in the corresponding order, place a prepreg between adjacent core boards, and press them together in a press to make a laminated board with multi-layer circuit patterns.

[0017] In some embodiments, in S1, a copper layer is formed on the hole wall by electroplating or immersion copper.

[0018] In some embodiments, the method of the first back drilling and / or the second back drilling includes: using a CNC drilling machine to drill holes in the conductive holes at a depth and along the line surface.

[0019] In some embodiments, during back drilling in S2, the center of the first back drill hole coincides with the center of the first conductive hole, and the center of the second back drill hole coincides with the center of the second conductive hole.

[0020] In some embodiments, the diameter of the first back-drilled hole is 0.1 to 0.3 mm larger than the diameter of the first conductive hole; and the diameter of the second back-drilled hole is 0.1 to 0.3 mm larger than the diameter of the second conductive hole.

[0021] In some embodiments, the diameter of the first back-drilled hole is 0.2 mm larger than the diameter of the first conductive hole; the diameter of the second back-drilled hole is 0.2 mm larger than the diameter of the second conductive hole.

[0022] In some embodiments, in S3, when the depth of the first back drill hole is less than the depth of the second back drill hole, the bottom of the connecting groove is aligned with the bottom of the first back drill hole.

[0023] The beneficial effects of the transverse compensation machining method for continuous hole back drilling of the present invention are as follows:

[0024] The transverse compensation processing method for back drilling of interconnected holes of the present invention performs back drilling on adjacent conductive holes simultaneously. After back drilling, the position between the back drilled holes corresponding to the adjacent conductive holes is removed, so that the first back drilled hole and the second back drilled hole are connected. Since the position between the first back drilled hole and the second back drilled hole, which are close to each other, is removed, the residual copper left on the back drilled hole wall due to the small back drill bit during back drilling can also be removed. It also overcomes the problem that the resin cannot adhere well to the hole wall due to the distortion between the positions of adjacent back drilled holes. Furthermore, it does not require strict control of the back drill bit diameter, thus improving the back drilling efficiency.

[0025] Another PCB board is provided, which is manufactured by the above-mentioned transverse compensation processing method of through-hole back drilling. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the transverse compensation machining method for continuous hole back drilling according to a specific embodiment of the present invention.

[0027] Figure 2 This is a cross-sectional view of the transverse compensation machining method for continuous hole back drilling according to a specific embodiment of the present invention. Detailed Implementation

[0028] Preferred embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0029] The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular forms “a,” “the,” and “the” as used in this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0030] It should be understood that although the terms "first," "second," "third," etc., may be used in this invention to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this invention, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0031] Example

[0032] Please see Figures 1-2 This embodiment discloses a lateral compensation machining method for continuous back-drilling, including the following steps: When it is necessary to make adjacent back-drilled holes, exemplarily, the distance between the electrical signal channels in adjacent back-drilled holes is ≤0.3mm.

[0033] S1. Fabricate a pressing plate, drill holes in the pressing plate to obtain through holes, fabricate a copper layer on the hole wall of the through holes, and electroplate the copper layer on the hole wall with tin so that the copper layer on the hole wall of the conductive hole is plated with a tin layer.

[0034] The above steps mainly involve creating a copper layer inside the hole wall of the via, at which point all layers of the circuit board are made conductive, including circuit networks that do not need to be connected. Tin plating is also applied to the copper layer on the hole wall to facilitate subsequent micro-etching of any residual copper left after back-drilling with a small back drill bit; in other words, it prepares the circuit for subsequent back-drilling with a small back drill bit.

[0035] S2. Select a first conductive hole and a second conductive hole that are close to each other. Perform a first back drill on the first conductive hole to obtain a first back drill hole. Perform a second back drill on the second conductive hole to obtain a second back drill hole.

[0036] Specifically, the first and / or second back drilling method involves using a CNC drilling machine to drill holes in the conductive holes according to the depth and orientation of the circuit lines. The CNC drilling machine is a high-precision machine that can better control the size of the back-drilled holes, thus improving the quality of the PCB board.

[0037] During back drilling, the center of the first back drill hole coincides with the center of the first conductive hole, and the center of the second back drill hole coincides with the center of the second conductive hole. By aligning the centers of the back drill holes and the conductive holes, the accuracy of subsequent back drilling is improved.

[0038] In this embodiment, the diameter of the first back-drilled hole is 0.1 to 0.3 mm larger than the diameter of the first conductive hole; the diameter of the second back-drilled hole is 0.1 to 0.3 mm larger than the diameter of the second conductive hole. Preferably, the diameter of the first back-drilled hole is 0.2 mm larger than the diameter of the first conductive hole; the diameter of the second back-drilled hole is 0.2 mm larger than the diameter of the second conductive hole.

[0039] Although a smaller back drill diameter was still used in this back drill, the subsequent lateral compensation effectively removed residual copper. Using a smaller back drill also significantly improved back drill efficiency.

[0040] S3. Drill a connecting groove at the adjacent positions of the first back drill hole and the second back drill hole to connect the first back drill hole and the second back drill hole, thus completing the back drilling.

[0041] The above steps involve drilling a connecting groove at the adjacent positions of the first back-drilled hole and the second back-drilled hole to directly remove residual copper on the hole wall, while also removing residual copper on the outside of the back-drilled hole, ensuring that no residual copper remains in the back-drilled hole.

[0042] S4. Perform micro-etching on the back-drilled laminate to remove the back-drilled copper slag and burrs from the hole opening, and then perform tin stripping on the laminate.

[0043] The above steps remove residual copper and burrs from the back-drilled hole openings through micro-etching, while the tin layer protects the signal channels on the non-back-drilled holes in the conductive holes. After micro-etching, the tin layer can be removed.

[0044] S5. Simultaneously, the first back drill hole and the second back drill hole are filled with resin, the resin is dried and cured, and then the resin overflowing from the hole is ground.

[0045] The above steps involve filling the walls of adjacent back-drilled holes with resin, then curing the resin, and finally grinding to smooth out the resin overflowing from the back-drilled holes and conductive orifices.

[0046] In this embodiment, the manufacturing steps of the pressing plate include:

[0047] S11. Cut the core board by stacking the core board into a copper-clad laminate and cutting the copper-clad laminate.

[0048] S12. Apply a film to the copper-clad laminate and expose it to transfer the preset circuit pattern to the corresponding copper-clad laminate. Etch the copper-clad laminate to produce a core board containing the circuit pattern.

[0049] S13. Stack all core boards in the corresponding order, place a prepreg between adjacent core boards, and press them together in a press to make a laminated board with multi-layer circuit patterns.

[0050] In this embodiment, in S1, a copper layer is formed on the hole wall by electroplating or immersion copper.

[0051] In this embodiment, in S3, when the depth of the first back drill hole is less than the depth of the second back drill hole, the bottom of the connecting groove is aligned with the bottom of the first back drill hole.

[0052] The drilling depth for connecting grooves is based on the shallow depth of the back drill hole. This not only enables the connection between the first and second back drill holes, but also minimizes the workload of drilling connecting grooves.

[0053] In this process, after drilling the back hole, the CNC drilling machine simultaneously opens the connecting groove, simplifying the production procedure.

[0054] In this embodiment, the method of the first back drilling and / or the second back drilling includes: using a CNC drilling machine to drill holes in the conductive hole according to the depth and the line surface.

[0055] In this embodiment, after S4, there are subsequent processes, which include:

[0056] S5. Make a copper layer in the holes of the lamination plate, that is, perform secondary copper plating, so that the resin surface in the back-drilled hole is covered with copper, so as to provide a corresponding copper layer for subsequent wiring on the resin surface.

[0057] S6. Apply film, expose and develop the laminate to copy the preset outer layer circuit pattern onto the laminate surface, and then etch to complete the outer layer circuit fabrication of the laminate.

[0058] S7. Perform solder resist printing on the circuitry of the laminated board, followed by subsequent processes.

[0059] The above embodiments avoid the problem of residual copper on the hole wall not being removed by connecting adjacent back-drilled holes.

[0060] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0061] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms 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 on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0062] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0063] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this application.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for lateral compensation machining of continuous hole back drilling, characterized in that, When it is necessary to create adjacent back drill holes, the following steps are included: S1. Fabricate a pressing plate, drill holes in the pressing plate to obtain through holes, fabricate a copper layer on the hole wall of the through holes to obtain conductive holes, and electroplate the copper layer on the hole wall with tin so that the copper layer on the hole wall of the conductive holes is plated with a tin layer. S2. First, perform a first back drill on the first conductive hole to obtain a first back drill hole, and then perform a second back drill on the second conductive hole to obtain a second back drill hole. S3. Drill a connecting groove at the adjacent positions of the first back drill hole and the second back drill hole to connect the first back drill hole and the second back drill hole, thus completing the back drilling. S4. Perform micro-etching on the back-drilled laminate to remove the back-drilled copper slag and burrs from the hole opening, and then perform tin stripping on the laminate. S5. Simultaneously, the first back drill hole and the second back drill hole are filled with resin, the resin is dried and cured, and then the resin overflowing from the hole is ground.

2. The transverse compensation machining method for continuous hole back drilling according to claim 1, characterized in that, The manufacturing steps of the pressed plate include: S11. Cut the core board by stacking the core board into a copper-clad laminate and cutting the copper-clad laminate. S12. Apply a film to the copper-clad laminate and expose it to transfer the preset circuit pattern to the corresponding copper-clad laminate. Etch the copper-clad laminate to produce a core board containing the circuit pattern. S13. Stack all core boards in the corresponding order, place a prepreg between adjacent core boards, and press them together in a press to make a laminated board with multi-layer circuit patterns.

3. The transverse compensation machining method for continuous hole back drilling according to claim 1, characterized in that, In S1, a copper layer is formed on the hole wall by electroplating or immersion copper.

4. The transverse compensation machining method for continuous hole back drilling according to claim 3, characterized in that, The method of the first back drilling and / or the second back drilling includes: using a CNC drilling machine to drill holes in the conductive holes according to the depth and the line orientation.

5. The transverse compensation machining method for continuous hole back drilling according to claim 1, characterized in that, In S2, during back drilling, the center of the first back drill hole coincides with the center of the first conductive hole, and the center of the second back drill hole coincides with the center of the second conductive hole.

6. The transverse compensation machining method for continuous hole back drilling according to claim 1, characterized in that, The diameter of the first back-drilled hole is 0.1~0.3mm larger than the diameter of the first conductive hole; The diameter of the second back-drilled hole is 0.1~0.3mm larger than the diameter of the second conductive hole.

7. The transverse compensation machining method for continuous hole back drilling according to claim 1, characterized in that, The diameter of the first back-drilled hole is 0.2 mm larger than the diameter of the first conductive hole; the diameter of the second back-drilled hole is 0.2 mm larger than the diameter of the second conductive hole.

8. The transverse compensation machining method for continuous hole back drilling according to claim 1, characterized in that, In S3, when the depth of the first back drill hole is less than the depth of the second back drill hole, the bottom of the connecting groove is aligned with the bottom of the first back drill hole.

9. A PCB board, characterized in that, It is prepared by the transverse compensation machining method of the continuous hole back drilling as described in any one of claims 1 to 8.

Images