PCB resin hole plugging and resin board grinding technological process manufacturing method

Abstract

The invention belongs to the field of PCB (printed circuit board) processing, and particularly relates to a PCB resin hole plugging and resin board grinding technological process manufacturing method. The method comprises the following steps: S1, drilling: drilling a PCB by using a numerical control drilling machine; s2, copper plating: performing PTH copper deposition treatment on the PCB to form a hole wall initial conductive layer, then performing cleaning and drying, performing copper treatment on the dried PCB, and thickening a copper layer of the hole wall to form a stable conductive layer; s3, negative film drying is conducted, the designed circuit pattern is subjected to the PCB resin hole plugging and resin board grinding process in the production process through the process of film pasting, exposure and development, the production process, production control and quality control of the PCB resin hole plugging and resin board grinding process can have a unified operation mode and control method, the production efficiency is improved, and the production cost is reduced. The process quality of the resin plug hole and the resin grinding plate is improved, and the conditions that the copper thickness is insufficient / too thick, the copper thickness is uneven and the plug holes are uneven in the actual production process of the resin plug hole and the resin grinding plate are avoided.

Description

Technical Field

[0001] This invention relates to the field of PCB board processing, specifically a process for manufacturing a PCB board using resin-filled holes and resin grinding. Background Technology

[0002] Resin plugging and resin grinding are key supporting processes in high-density interconnect (HDI) or high-frequency PCBs. The core is to fill through holes / blind holes with resin and then remove excess resin from the surface through grinding to achieve board surface flatness, laying the foundation for subsequent circuit fabrication or surface treatment (such as immersion gold or tin plating).

[0003] At present, all electronic PCB boards are developing and being laid out in a high-end, precise and advanced direction. Making full use of space and making products thin, light and small have become the research and development direction. The drilling and conduction of PCB boards and the placement of PAD components have become problems that must be solved. The design of resin plugging of PCB boards and resin grinding board provides a solution for this design.

[0004] However, in actual production, resin plugging + resin grinding may result in insufficient / excessive copper thickness, uneven copper thickness, and uneven plugging. Therefore, a process flow method for PCB board resin plugging + resin grinding is proposed to address the above problems. Summary of the Invention

[0005] To overcome the shortcomings of the prior art and solve at least one of the technical problems mentioned in the background art, the present invention proposes a PCB board resin hole plugging and resin grinding process manufacturing method.

[0006] The technical solution adopted by the present invention to solve its technical problem is: a PCB board resin hole plugging and resin grinding process manufacturing method, comprising the following steps;

[0007] S1: Drilling, using a CNC drilling machine to drill holes in the PCB board;

[0008] S2: Copper plating. The PCB board is subjected to PTH copper plating treatment to form an initial conductive layer on the hole wall. After cleaning and drying, the dried PCB board is subjected to copper plating to thicken the copper layer on the hole wall to form a stable conductive layer.

[0009] S3: Negative dry film. Through the process of film application, exposure and development, the designed circuit pattern is transferred to the surface of the PCB board. After development, the cured dry film will cover the surface of the non-circuit area to prevent copper layer deposition in the subsequent copper plating process.

[0010] S4: Double copper plating, which involves applying double copper plating to the PCB board, further thickening the exposed circuits and vias by electroplating.

[0011] S5: Film removal and tin stripping. Use alkaline film removal solution to remove the dry film on the PCB board surface, clean and dry, and then dissolve the electroplated tin layer on the PCB board surface with an acidic solution.

[0012] S6: Resin plugging, inserting resin into the target hole on the PCB board, with a plugging fullness of 100%;

[0013] S7: Resin Grinding Board. A grinding machine is used to grind the surface of the PCB board, removing the excess resin that overflowed onto the board surface after plugging the holes, making the board surface flush with the resin inside the holes, while exposing the copper foil around the hole openings.

[0014] During production, the above-mentioned PCB board resin via plugging + resin grinding process can provide a unified operating method and control method for the production process, production management and quality control of the PCB board resin via plugging + resin grinding process, thereby improving the quality of the resin via plugging + resin grinding process and avoiding situations such as insufficient / excessive copper thickness, uneven copper thickness and uneven via plugging during actual production.

[0015] Preferably, in S6, when the resin plugs the hole, the target hole diameter is ≥0.4mm. The screen printing plugging method is used, with windows made on the screen corresponding to the target hole position, and the resin is pressed into the hole with a scraper.

[0016] The target hole diameter is ≤0.3mm. Vacuum plugging is used. The board is placed in a vacuum chamber and the resin is drawn into the hole under negative pressure. The vacuum degree is -80kPB to -90kPB.

[0017] Preferably, in step S6, after the resin is used to plug the holes, the PCB board is sent into a curing chamber, heated to 80-100°C, cured for 15-30 minutes, and the resin curing degree is 30%-50%.

[0018] Preferably, in S7, the process of grinding the PCB board surface with a grinding machine includes the following steps:

[0019] A1: Coarse grinding: Use an 800-1000 grit diamond grinding wheel to quickly remove most of the excess resin from the surface.

[0020] A2: Use a 1200-1500 grit resin grinding wheel for fine grinding, and the copper thickness after grinding should be 0.6-0.8 mil.

[0021] Preferably, in step S7, when the grinding machine grinds the PCB board surface, a cooling spray device is installed next to the grinding wheel of the grinding machine to spray deionized water to reduce the grinding temperature.

[0022] Preferably, in S6, the target hole needs to be pretreated before resin plugging. The pretreatment process includes the following steps:

[0023] B1: Degreasing. Place the PCB board in an alkaline degreasing agent at a temperature of 30-35℃ for 60-90 seconds.

[0024] B2: Water wash, spray with deionized water for 2-3 minutes to remove residual degreaser from the PCB board;

[0025] B3: Pickling and activation. Immerse the PCB board in a 5% dilute sulfuric acid solution at 25-30℃ for 30 seconds to remove the oxide film on the surface of the copper layer on the hole wall.

[0026] B4: Etching, using a spray etching machine to spray etching solution onto the PCB board to dissolve burrs at the hole openings and roughen the hole walls;

[0027] B5: Drying, hot air drying of PCB boards.

[0028] Preferably, in B4, after etching is completed, the PCB board is immediately sprayed with deionized water for 3-5 minutes, then immersed in a 5% sodium carbonate solution for 30 seconds to neutralize the residual acidity, followed by rinsing with water for 1 minute, and then immersed in a 0.5% corrosion inhibitor solution for 30 seconds to form a passivation film on the copper layer surface of the hole wall.

[0029] Preferably, before resin plugging and resin grinding of the PCB board, 1 to 2 sample boards are taken for trial processing.

[0030] The advantages of this invention are:

[0031] 1. In the production process of this invention, the above-mentioned PCB board resin hole plugging + resin grinding process can be adopted to make the PCB board resin hole plugging + resin grinding process production flow, production control and quality control have a unified operation method and control method, improve the quality of resin hole plugging + resin grinding process, and avoid the situation of insufficient / excessive copper thickness, uneven copper thickness and uneven hole plugging in the actual production of resin hole plugging + resin grinding.

[0032] 2. In this invention, a first article is made for confirmation before the resin plugging + resin grinding process, which can ensure the production quality of the board according to the designed process and each station of the process. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a flowchart of the method of the present invention;

[0035] Figure 2 This is a flowchart of the grinding method of the grinding machine of the present invention;

[0036] Figure 3 This is a flowchart of the resin plugging pretreatment method of the present invention. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Specific implementation examples are given below.

[0039] Please see Figure 1 As shown, a method for manufacturing a PCB board using resin-filled holes and resin-ground board includes the following steps;

[0040] S1: Drilling, using a CNC drilling machine to drill holes in the PCB board;

[0041] S2: Copper plating. The PCB board is subjected to PTH copper plating treatment to form an initial conductive layer on the hole wall. After cleaning and drying, the dried PCB board is subjected to copper plating to thicken the copper layer on the hole wall to form a stable conductive layer.

[0042] S3: Negative dry film. Through the process of film application, exposure and development, the designed circuit pattern is transferred to the surface of the PCB board. After development, the cured dry film will cover the surface of the non-circuit area to prevent copper layer deposition in the subsequent copper plating process.

[0043] S4: Double copper plating, which involves applying double copper plating to the PCB board, further thickening the exposed circuits and vias by electroplating.

[0044] S5: Film removal and tin stripping. Use alkaline film removal solution to remove the dry film on the PCB board surface, clean and dry, and then dissolve the electroplated tin layer on the PCB board surface with an acidic solution.

[0045] S6: Resin plugging, inserting resin into the target hole on the PCB board, with a plugging fullness of 100%;

[0046] S7: Resin grinding board. The PCB board surface is ground with a grinding machine to remove the part that overflowed onto the board surface after the hole was plugged, so that the board surface is flush with the resin in the hole, and at the same time exposes the copper foil around the hole opening.

[0047] During production, the above-mentioned PCB board resin via plugging + resin grinding process can provide a unified operating method and control method for the production process, production management and quality control of the PCB board resin via plugging + resin grinding process, thereby improving the quality of the resin via plugging + resin grinding process and avoiding situations such as insufficient / excessive copper thickness, uneven copper thickness and uneven via plugging during actual production.

[0048] Furthermore, in S6, when using resin to plug holes, if the target hole diameter is ≥0.4mm, screen printing is used for plugging. A window is made on the screen corresponding to the target hole position, and a scraper is used to press the resin into the hole. If the target hole diameter is ≤0.3mm, vacuum plugging is used. The board is placed in a vacuum chamber, and the resin is drawn into the hole under negative pressure. The vacuum degree is -80kPB to -90kPB. During production, the above two methods are used, and different resin plugging methods are selected for different hole diameters. This ensures the fullness of the plugging and improves the efficiency of plugging.

[0049] Furthermore, in S6, after the resin plugging is completed, the PCB board is sent into the curing chamber, heated to 80-100℃, and cured for 15-30 minutes, with a resin curing degree of 30%-50%. During production, to avoid resin falling off during transportation and grinding, the PCB board is sent into the curing chamber for preliminary resin curing and shaping after the resin plugging is completed. This prevents the resin from falling off during subsequent transportation or grinding. At the same time, the above curing temperature and time can control the resin curing degree at 30%-50%, avoiding the situation where over-curing will lead to difficulties in subsequent grinding and under-curing will easily cause the resin to stick to the grinding wheel.

[0050] Furthermore, such as Figure 2 As shown, in S7, the process of grinding the PCB board surface with a grinding machine includes the following steps: A1: Coarse grinding: Use an 800-1000 grit diamond grinding wheel to quickly remove most of the excess resin from the surface; A2: Use a 1200-1500 grit resin grinding wheel for fine grinding, and grind the copper thickness to 0.6-0.8 mil.

[0051] Furthermore, in S7, when the grinding machine grinds the PCB board surface, a cooling spray device is installed next to the grinding wheel of the grinding machine to spray deionized water to reduce the grinding temperature. During processing, spraying deionized water to reduce the grinding temperature can prevent copper foil oxidation and prevent resin debris from sticking to the grinding wheel and causing scratches on the board surface.

[0052] Furthermore, such as Figure 3 As shown in S6, the target hole needs to be pretreated before resin plugging. The pretreatment process includes the following steps:

[0053] B1: Degreasing. Place the PCB board in an alkaline degreasing agent at a temperature of 30-35℃ for 60-90 seconds.

[0054] B2: Water wash, spray with deionized water for 2-3 minutes to remove residual degreaser from the PCB board;

[0055] B3: Pickling and activation. Immerse the PCB board in a 5% dilute sulfuric acid solution at 25-30℃ for 30 seconds to remove the oxide film on the surface of the copper layer on the hole wall.

[0056] B4: Etching, using a spray etching machine to spray etching solution onto the PCB board to dissolve burrs at the hole openings and roughen the hole walls;

[0057] B5: Drying, hot air drying of PCB boards;

[0058] During production, copper burrs with a height of 0.05 to 0.1 mm are easily left on the edge of the hole after drilling. If they are not removed, they will be pushed up by the resin when plugging the hole, forming local gaps. After subsequent curing, voids or resin peeling are likely to occur. Therefore, before resin plugging, a weak acid etching solution is used to selectively dissolve the copper burrs at the hole opening. At the same time, the etching solution will form tiny pits on the surface of the copper layer on the hole wall, with a hole wall roughness RB of 0.5 to 1.0 μm, increasing the contact area between the resin and the copper layer and improving adhesion. Especially for smooth copper layers, the adhesion can be improved by more than 30% after roughening. In addition, during the etching process, the copper powder and drilling debris remaining in the hole will be washed away with the etching solution, avoiding impurities from embedding in the resin and causing poor plugging, thus ensuring the quality of plugging. Before etching, an oil removal process is carried out to avoid oil stains blocking the etching solution and causing local burrs to be unable to dissolve.

[0059] Furthermore, in B4, after etching is completed, the PCB board is immediately sprayed with deionized water for 3-5 minutes, then immersed in a 5% sodium carbonate solution for 30 seconds to neutralize the residual acidity, followed by rinsing with water for 1 minute, and then immersed in a 0.5% corrosion inhibitor solution for 30 seconds to form a passivation film on the copper layer surface of the hole wall.

[0060] During processing, the copper layer on the hole wall is easily oxidized during subsequent washing and drying. The oxide layer has a smooth and inactive surface, and the resin cannot bond tightly to the hole wall. After curing, "resin peeling off from the hole wall" is likely to occur, forming voids or surface depressions in the hole. During subsequent grinding, the resin may also fall off, requiring re-plugging. By adding the above process, a passivation film can be formed on the surface of the copper layer on the hole wall, thereby preventing the copper layer on the hole wall from oxidizing during subsequent washing and drying, thus ensuring a tight bond between the resin and the control.

[0061] Furthermore, before resin plugging and resin grinding of the PCB board, 1 to 2 sample boards are taken for trial processing. During processing, a first piece confirmation is made before the resin plugging + resin grinding process to ensure the production quality of each station of the designed process.

[0062] Working principle: During production, the above-mentioned PCB board resin hole plugging + resin grinding process can provide a unified operation method and control method for the production process, production control and quality control of the PCB board resin hole plugging + resin grinding process, thereby improving the quality of the resin hole plugging + resin grinding process and avoiding the occurrence of insufficient / excessive copper thickness, uneven copper thickness and uneven hole plugging in the actual production of resin hole plugging + resin grinding.

[0063] During production, the above two resin plugging methods are used, and different resin plugging methods are selected for different pore diameters. This can ensure the fullness of the plugging and improve the plugging efficiency.

[0064] During production, to avoid resin detachment during transport and grinding, the PCB board is placed in a curing chamber for initial resin curing and shaping after the resin is plugged. This prevents detachment during subsequent transport or grinding. The curing temperature and time mentioned above can control the degree of resin curing between 30% and 50%, avoiding the difficulties in subsequent grinding caused by over-curing and the tendency for under-curing to stick to the grinding wheel. During processing, deionization is sprayed to reduce the grinding temperature, which can prevent copper foil oxidation and prevent resin debris from sticking to the grinding wheel and causing scratches on the board surface.

[0065] During production, copper burrs with a height of 0.05 to 0.1 mm are easily left on the edge of the hole after drilling. If they are not removed, they will be pushed up by the resin when plugging the hole, forming local gaps. After subsequent curing, voids or resin peeling are likely to occur. Therefore, before resin plugging, a weak acid etching solution is used to selectively dissolve the copper burrs at the hole opening. At the same time, the etching solution will form tiny pits on the surface of the copper layer on the hole wall, with a hole wall roughness RB of 0.5 to 1.0 μm, increasing the contact area between the resin and the copper layer and improving adhesion. Especially for smooth copper layers, the adhesion can be improved by more than 30% after roughening. In addition, during the etching process, the copper powder and drilling debris remaining in the hole will be washed away with the etching solution, avoiding impurities from embedding in the resin and causing poor plugging, thus ensuring the quality of plugging. Before etching, an oil removal process is carried out to avoid oil stains blocking the etching solution and causing local burrs to be unable to dissolve.

[0066] During processing, the copper layer on the hole wall is easily oxidized during subsequent washing and drying. The oxide layer has a smooth and inactive surface, and the resin cannot bond tightly with the hole wall. After curing, "resin peeling off from the hole wall" is likely to occur, forming voids or surface depressions in the hole. During subsequent grinding, the resin may also fall off, requiring re-plugging. By adding the above process, a passivation film can be formed on the surface of the copper layer on the hole wall, thereby preventing the copper layer on the hole wall from oxidizing during subsequent washing and drying, thus ensuring a tight bond between the resin and the control.

[0067] During processing, a first piece confirmation is made before the resin plugging + resin grinding process to ensure the production quality of each station of the designed process.

[0068] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0069] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for manufacturing a PCB board using resin-filled vias and resin grinding process, comprising the following steps; S1: Drilling, using a CNC drilling machine to drill holes in the PCB board; S2: Copper plating. The PCB board is subjected to PTH copper plating treatment to form an initial conductive layer on the hole wall. After cleaning and drying, the dried PCB board is subjected to copper plating to thicken the copper layer on the hole wall to form a stable conductive layer. S3: Negative dry film. Through the process of film application, exposure and development, the designed circuit pattern is transferred to the surface of the PCB board. After development, the cured dry film will cover the surface of the non-circuit area to prevent copper layer deposition in the subsequent copper plating process. S4: Double copper plating, which involves applying double copper plating to the PCB board, further thickening the exposed circuits and vias by electroplating. S5: Film removal and tin stripping. Use alkaline film removal solution to remove the dry film on the PCB board surface, clean and dry, and then dissolve the electroplated tin layer on the PCB board surface with an acidic solution. S6: Resin plugging, inserting resin into the target hole on the PCB board, with a plugging fullness of 100%; S7: Resin Grinding Board. A grinding machine is used to grind the surface of the PCB board to remove the portion that overflowed onto the board surface after plugging the holes, making the board surface flush with the resin inside the holes, while exposing the copper foil around the hole openings.

2. The method for manufacturing a PCB board using resin-filled vias and resin grinding process according to claim 1, characterized in that: In S6, when filling holes with resin, if the target hole diameter is ≥0.4mm, the screen printing method is used to fill the holes. A window is made on the screen corresponding to the target hole position, and the resin is pressed into the hole with a scraper. The target hole diameter is ≤0.3mm. Vacuum plugging is used. The board is placed in a vacuum chamber and the resin is drawn into the hole under negative pressure. The vacuum degree is -80kPB to -90kPB.

3. The method for manufacturing a PCB board using resin-filled vias and resin grinding process according to claim 1, characterized in that: In S6, after the resin is used to plug the holes, the PCB board is sent into the curing chamber, heated to 80-100℃, cured for 15-30 minutes, and the resin curing degree is 30%-50%.

4. The PCB board resin plugging and resin grinding process according to claim 1, in step S7, the process of grinding the PCB board surface with a grinding machine includes the following steps: A1: Coarse grinding: Use an 800-1000 grit diamond grinding wheel to quickly remove most of the excess resin from the surface. A2: Use a 1200-1500 grit resin grinding wheel for fine grinding, and the copper thickness after grinding should be 0.6-0.8 mil.

5. The method for manufacturing a PCB board using resin-filled vias and resin grinding process according to claim 1, characterized in that: In step S7, when the grinding machine grinds the PCB board surface, a cooling spray device is installed next to the grinding wheel of the grinding machine to spray deionized water to reduce the grinding temperature.

6. The method for manufacturing a PCB board using resin-filled vias and resin grinding process according to claim 1, characterized in that: In S6, the target hole needs to be pretreated before resin plugging. The pretreatment process includes the following steps: B1: Degreasing. Place the PCB board in an alkaline degreasing agent at a temperature of 30-35℃ for 60-90 seconds. B2: Water wash, spray with deionized water for 2-3 minutes to remove residual degreaser from the PCB board; B3: Pickling and activation. Immerse the PCB board in a 5% dilute sulfuric acid solution at 25-30℃ for 30 seconds to remove the oxide film on the surface of the copper layer on the hole wall. B4: Etching, using a spray etching machine to spray etching solution onto the PCB board to dissolve burrs at the hole openings and roughen the hole walls; B5: Drying, hot air drying of PCB boards.

7. The method for manufacturing a PCB board using resin-filled vias and resin grinding process according to claim 6, characterized in that: In B4, after etching is completed, the PCB board is immediately sprayed with deionized water for 3-5 minutes. Then it is immersed in a 5% sodium carbonate solution for 30 seconds to neutralize the residual acidity. After that, it is rinsed with water for 1 minute and then immersed in a 0.5% corrosion inhibitor solution for 30 seconds to form a passivation film on the copper layer surface of the hole wall.

8. The method for manufacturing a PCB board using resin-filled vias and resin grinding process according to claim 1, characterized in that: Before resin plugging and resin grinding of the PCB board, take 1-2 sample boards for trial processing.

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