PCB processing method

Abstract

The invention relates to the technical field of PCB (Printed Circuit Board) processing, in particular to a PCB processing method, which comprises the following steps of: firstly, drilling a back-drilled small hole, a resin plugging hole and a metal slurry plugging hole together and metalizing, and then selectively plugging metal slurry and then plugging resin in a dry film hole sealing manner, so that the production process is simplified, the production efficiency is improved, and the production cost is reduced. All resin plugging holes and back drilling small holes can be prevented from being plugged when metal slurry is plugged. The method comprises the following steps of: firstly, performing film stripping treatment, then performing back drilling to form back drilling small holes, and finally, performing resin plugging on all resin plugging holes and the back drilling small holes, so that the whole number of times of dry film hole covering can be reduced, and the process is simplified; and finally, secondary drilling is carried out on the resin plugging hole in the preset position, a through hole without resin plugging is obtained, the problem that the copper thickness of a finished product is too large and is difficult to etch due to multiple times of drilling and hole metallization is effectively avoided, the technological process is simplified, and the machining cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of PCB board processing, and particularly relates to a method for processing a PCB board. Background Art

[0002] With the development of electronic products towards being lighter, thinner and smaller, PCB boards have also been pushed towards high density and high difficulty. Customers' requirements are getting higher and higher. There are also some customer product designs that change blind vias to back drills, back drill holes are filled with resin, and at the same time, some through holes require filling with metal paste or resin. After hole filling, the bottom surface of the printed board is plated flat. Such product designs are relatively complex. In the current PCB board processing technology, the general process is roughly: lamination - drilling resin-filled holes and small back drill holes - hole metallization - back drill process - resin hole filling process - drilling holes that need to be filled with metal paste - hole metallization - copper paste hole filling process - drilling holes that do not need to be filled with resin - then going through hole metallization - pattern making and other operations. The above manufacturing method has a long process. The outer layer of the PCB board requires 3 times of drilling and 3 times of hole metallization, which will cause the outer layer finished copper thickness to be too thick, making it difficult to process products with small line width and spacing, and having a long processing cycle and high production cost.

[0003] In view of the above situation, the patent with the publication number CN 104717845 A discloses a process method for resin hole filling of the outer layer circuit board of a multi-layer circuit board. By plating enough copper for resin hole filling at one time and then performing copper reduction treatment after resin hole filling, it can not only avoid the problem that the copper foil on the surface of the outer layer circuit board is too thick and difficult to control etching to meet the circuit design requirements, but also greatly simplifies the process flow and significantly reduces the production cost compared with the existing hole plating method. Although this patent can effectively avoid the problem of too thick copper foil on the surface of the outer layer circuit board, this patent requires copper reduction treatment, resulting in a large amount of waste. Summary of the Invention

[0004] To achieve the above object, the purpose of the present invention is to provide a method for processing a PCB board. This method for processing a PCB board reduces the number of drilling and hole metallization through a selective plugging method, which is beneficial to controlling the finished copper thickness and facilitating the production of the outer layer pattern, while simplifying the process and reducing the processing cost.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0006] A method for processing a PCB board, comprising the following steps:

[0007] Step S100, pre-treating the PCB board;

[0008] Step S200, after laminating the pre-treated PCB board, drill resin-filled holes and metal paste-filled holes;

[0009] Step S300: Perform hole metallization on all the resin-filled holes and metal paste-filled holes on the PCB board obtained in step S200, and then perform dry film hole sealing operation on the end faces of the resin-filled holes on the outer surface of the corresponding side of the PCB board;

[0010] Step S400: Plug the metal paste-filled holes on the PCB board with copper paste, and bake the PCB board to cure the copper paste in the metal paste-filled holes; after the copper paste is cured, grind the copper paste bumps on the ports of the metal paste-filled holes, and after all the copper paste bumps are polished, strip the remaining dry film on the PCB board;

[0011] Step S500: Back drill the resin-filled holes at the preset positions on the PCB board to obtain back drill small holes, fill all the resin-filled holes and back drill small holes with resin, and then bake the PCB board to cure the resin; after the resin in the resin-filled holes and back drill small holes is cured, grind the resin bumps on the ports of the resin-filled holes and back drill small holes;

[0012] Step S600: Drill through holes in the resin-filled holes at the preset positions on the PCB board, and perform hole metallization on the through holes;

[0013] Step S700: Fabricate the outer layer pattern of the PCB board.

[0014] In some possible embodiments, step S300 specifically includes the following steps:

[0015] Step S310: Perform dry film pressing treatment on the outer surface of the PCB board, and the dry film completely adheres to the outer surface of the PCB board;

[0016] Step S320: Perform graphic exposure treatment on the dry film to complete graphic transfer;

[0017] Step S330: Perform development treatment on the dry film obtained in step S320 in sequence, so that only the part of the dry film in the area where the resin-filled holes are located is retained, and the dry film hole sealing operation for the resin-filled holes is completed.

[0018] In some possible embodiments, in step S330, the difference between the diameter of the dry film plugging the end face of the resin-filled hole and the diameter of the resin-filled hole is greater than 6 mil.

[0019] In some possible embodiments, after the copper paste bumps on the ports of the metal paste-filled holes in step S400 are ground flat, the end faces of the copper paste bumps also need to be browned.

[0020] In some possible embodiments, the hole metallization treatment specifically includes: performing electroless copper plating on the PCB board, and then performing electroplating.

[0021] In some possible embodiments, the thickness of the copper in the holes metallized for resin hole plugging, metal paste hole plugging in step S200 and via holes in step S600 is between 10 - 25 um.

[0022] In some possible embodiments, in step S400, the specific operation of the film stripping treatment is as follows: dissolve the dry film on the PCB board with an alkaline solution, then rinse it with pure water at least twice, and dry it to complete the film stripping treatment.

[0023] In some possible embodiments, the alkaline solution is sodium hydroxide or potassium hydroxide solution.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: in a PCB board processing method of the present invention, small backdrilled holes, resin hole plugging and metal paste hole plugging are drilled together and metallized first, and then by the way of dry film hole sealing, selective metal paste plugging first and then resin plugging are realized, which simplifies the production process and can avoid plugging all resin hole plugs and backdrilled small holes when plugging the metal paste. Then through the film stripping treatment, the backdrilled small holes are backdrilled again, and finally resin is plugged into all resin hole plugs and backdrilled small holes. Such a design can reduce the overall number of times of dry film covering holes and simplify the process; finally, the resin hole plugs at the preset positions are drilled twice to obtain via holes that do not need resin plugging, effectively avoiding the problem that the finished copper thickness is too thick to be etched due to multiple drilling and hole metallization, and simplifying the process flow and saving processing costs. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 It is a flowchart of the PCB processing method provided by the embodiment of the present invention. Detailed Embodiments

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Hereinafter, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present disclosure, unless otherwise specified, the meaning of "a plurality" is two or more.

[0028] Referring to Figure 1 a PCB board processing method, which includes the following steps:

[0029] Step S100, preprocessing the PCB board;

[0030] Step S200, after laminating the preprocessed PCB board, drill resin plug holes and metal paste plug holes;

[0031] Step S300, perform hole metallization on all the resin plug holes and metal paste plug holes on the PCB board obtained in Step S200, and then perform dry film hole sealing operation on the end faces of the resin plug holes on the outer surface of the corresponding side of the PCB board;

[0032] Step S400, perform copper paste plugging on the metal paste plug holes on the PCB board, bake the PCB board to cure the copper paste in the metal paste plug holes; after the copper paste is cured, grind the copper paste bumps on the ports of the metal paste plug holes, and after all the copper paste bumps are polished, perform stripping treatment on the remaining dry film on the PCB board;

[0033] Step S500, back drill the resin plug holes at the preset positions on the PCB board to obtain back drill small holes, fill all the resin plug holes and back drill small holes with resin, and then bake the PCB board to cure the resin; after the resin in the resin plug holes and back drill small holes is cured, then grind the resin bumps on the ports of the resin plug holes and back drill small holes;

[0034] Step S600, drill through holes in the resin plug holes at the preset positions on the PCB board, and perform hole metallization on the through holes;

[0035] Step S700, perform outer layer pattern making on the PCB board.

[0036] Among them, in the above embodiments, the pretreatment in step S100 mainly cleans each layer of the PCB board to avoid impurities being mixed in the process of multi-layer lamination, which may affect the forming and quality of the entire PCB board. In step S200, the lamination operation of the PCB board is a conventional operation, which will not be elaborated in this application. In step S400, all copper paste bumps are polished so that only the outermost layer is not protruded, which is convenient for heat dissipation in the later stage and also facilitates subsequent processing, such as copper foil precipitation and etching on the board surface; in step S500, the process method for plugging the resin holes and back-drilled small holes with resin is the aluminum sheet resin plugging method.

[0037] This PCB board processing method first drills and metallizes the back-drilled small holes, resin holes, and metal paste holes together, and then uses the dry film sealing method to selectively plug the metal paste first and then the resin, which simplifies the production process and can avoid blocking all resin holes and back-drilled small holes when plugging the metal paste. Then through the film stripping process, the back-drilled small holes are back-drilled again, and finally all resin holes and back-drilled small holes are plugged with resin. Such a design can reduce the number of times of dry film covering holes as a whole, and simplify the process; finally, the resin holes at the preset positions are drilled twice to obtain through holes that do not need to be plugged with resin, effectively avoiding the problem that the finished copper thickness is too thick and difficult to etch due to multiple drilling and hole metallization, and simplifying the process flow and saving processing costs.

[0038] In some possible embodiments, step S300 specifically includes the following steps:

[0039] Step S310: Perform dry film pressing treatment on the outer surface of the PCB board, and the dry film completely adheres to the outer surface of the PCB board;

[0040] Step S320: Perform graphic exposure treatment on the dry film to complete graphic transfer;

[0041] Step S330: The dry film obtained in step S320 is sequentially developed, so that only the part of the dry film in the area where the resin holes are located remains, and the dry film sealing operation of the resin holes is completed.

[0042] In step S310, the dry film pressing treatment is a conventional processing method, which will not be elaborated in this application; in step S330, the difference between the diameter of the dry film plugging the end face of the resin hole and the diameter of the resin hole is greater than 6 mil. Such a design enables the dry film to completely plug the resin hole, ensuring a stable connection between the dry film and the end face of the resin hole, and avoiding copper powder from infiltrating into the resin hole during the copper paste plugging in step S400. The dry film in this application is a three-layer sandwich structure composed of a polyester film, a polyolefin film, and a photosensitive film. In fact, the dry film is a conventional material, which will not be elaborated in this application.

[0043] In some possible embodiments, subsequent processing is also required on the outer surface of the PCB board, such as laminating with other circuit boards. In order to facilitate the connection of the later-formed outer-layer circuit board with other structures, after the copper paste bumps on the ports of the metal paste-filled holes are ground flat in step S400, the end faces of the copper paste bumps also need to be browned. Among them, browning, as the first step in the lamination process of the circuit board, is an essential process in the circuit board lamination process. The browning process can adopt the technical solution in Patent CN112739064A - Circuit Board and Its Browning Process, which is not elaborated in detail in this application.

[0044] In some possible embodiments, the hole metallization treatment specifically includes: depositing copper on the PCB board and then electroplating. In fact, these are all conventional operations and are not elaborated in detail in this application. Just process with conventional copper deposition process and electroplating process.

[0045] In addition, in the above embodiments, the hole copper thickness of the resin-filled holes, metal paste-filled holes in step S200, and the through holes in step S600 during hole metallization is between 10 - 25 um.

[0046] In some possible embodiments, the specific operation of the film stripping treatment in step S400 is: dissolving the dry film on the PCB board with an alkaline solution, then rinsing with pure water at least twice and drying to complete the film stripping treatment. Among them, the alkaline solution is sodium hydroxide or potassium hydroxide solution, and the concentration of the alkaline solution can be adapted according to the different components of the dry film. In fact, this design is also a conventional technical means, so it is not elaborated in detail in this application either. After the film stripping treatment, the resin-filled holes are completely exposed, which facilitates the subsequent resin filling operation.

[0047] In addition, in step S700, the outer-layer pattern of the PCB board is made, which is mainly to form copper foil on the outer layer. This operation is a conventional one. For example, first transfer the film image to the board surface of the PCB board obtained in step S600; then form a copper foil layer on the board surface of the PCB board by means of pattern electroplating, and then etch the required circuit on the board surface of the PCB board by means of outer-layer etching. Of course, this design is just a simple way, and this application is not limited to the above example operations.

[0048] The above is only the specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A PCB board processing method, characterized in that: The following steps are involved: Step S100, pre-processing the PCB board; Step S200, after laminating the pre-treated PCB board, drilling the resin plugging holes and the metal paste plugging holes; Step S300, performing hole metallization processing on all the resin plug holes and metal paste plug holes on the PCB board obtained in step S200, and then performing a dry film sealing operation on the end surface of the resin plug hole on the outer surface of the corresponding side of the PCB board; Step S400, plugging the metal paste holes on the PCB board with copper paste, baking the PCB board to solidify the copper paste in the metal paste holes; after the copper paste is solidified, grinding the copper paste bumps on the ports of the metal paste holes, and after all the copper paste bumps are polished, stripping the dry film remaining on the PCB board; Step S500, back-drilling the plug resin holes at the preset positions on the PCB board to obtain back-drilled small holes, and filling all the plug resin holes and the back-drilled small holes with resin, and then baking the PCB board to solidify the resin; after the resin in the plug resin holes and the back-drilled small holes is solidified, the resin bumps on the plug resin holes and the back-drilled small holes are ground flat; Step S600, drilling the resin plug hole at the preset position of the PCB board to obtain a through hole, and performing hole metallization treatment on the through hole; Step S700: producing outer layer graphics for the PCB board.

2. A PCB board processing method according to claim 1, characterized in that: Step S300 specifically includes the following steps: Step S310, performing a dry film pressing process on the outer surface of the PCB board, so that the dry film completely adheres to the outer surface of the PCB board; Step S320, performing pattern exposure processing on the dry film to complete pattern transfer; Step S330, the dry film obtained in step S320 is subjected to development treatment in sequence, so that only the portion of the dry film where the resin plugging hole is located is retained, thereby completing the dry film sealing operation of the resin plugging hole.

3. A PCB board processing method according to claim 2, characterized in that: In step S330, the difference between the diameter of the dry film sealing the end surface of the resin plugging hole and the diameter of the resin plugging hole is greater than 6 mil.

4. A PCB board processing method according to claim 1, characterized in that: In step S400, after the copper paste bumps on the ports of the metal paste plug holes are ground flat, the end surfaces of the copper paste bumps need to be browned.

5. A PCB board processing method according to claim 1, characterized in that: The hole metallization process specifically includes: copper deposition on the PCB board and then electroplating.

6. A PCB board processing method according to claim 1 or 5, characterized in that: The copper thickness of the resin plugging holes and metal paste plugging holes in step S200 and the through holes metallized in step S600 is between 10-25 um.

7. A PCB board processing method according to claim 1, characterized in that: In step S400, the specific operation of the film stripping treatment is: using an alkaline solution to dissolve the dry film on the PCB board, then rinsing it with pure water at least twice, and drying it to complete the film stripping treatment.

8. A PCB board processing method according to claim 7, characterized in that: The alkaline solution is sodium hydroxide or potassium hydroxide solution.

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