Solder-resistant single-side windowing plug hole plate processing technology

Abstract

The invention discloses a processing technology of a solder-resistant single-side windowing plug hole plate, which solves the problem of oil leakage of a through hole at a plug hole single-side windowing position by using independently researched and developed solder-resistant plug hole printing ink with proper viscosity, improving a developing operation method, using a high-temperature tunnel furnace device for segmented heating and curing and the like. Experiments prove that after the processing technology of the solder-resistant single-side windowing plug hole plate is improved, the defect rate of developing single-side windowing via hole oil emission PQC visual inspection is reduced to 0% from the original more than 80%; the AVI full inspection reject ratio of the FQC finished product is reduced to 0.05% from the original more than 10%, the oil leakage phenomenon of the through hole at the single-side windowing position of the plug hole is obviously improved, and the reworking and repairing cost of resistance welding is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of circuit board manufacturing, in particular to a processing technology of a solder resist single-sided window plugging plate. Background Art

[0002] PCB (Printed Circuit Board), whose Chinese name is printed circuit board, also known as printed circuit board, printed circuit board, is an important electronic component and the support of electronic components. Because it is made by electronic printing technology, it is called printed circuit board.

[0003] The solder mask single-sided window plugging board is an important part of the PCB manufacturing process. By opening windows in the solder mask layer and filling the via holes, the welding quality, reliability and service life of the PCB can be effectively improved. It is mainly used to protect the surface of the circuit board and define the pad area. Single-sided windowing refers to opening windows in the solder mask layer on one side of the PCB. The window area is usually the pad position, and these areas will not be covered by the solder mask layer; plugging holes refers to filling resin or other materials in the via holes to prevent solder from flowing into the holes during the welding process, affecting the welding quality of the PCB and the reliability of the circuit;

[0004] However, after exposure and development, oil overflow often occurs in the via holes of PCBs. The solder mask plugging ink overflows onto the copper surface of the single-sided windowed via holes, affecting product quality and component welding, resulting in increased rework and repair costs. Before the applicant improved the processing technology of the solder mask single-sided windowed plugging board, the defective rate of PCBs was more than 80% by visual inspection using PQC (Process Quality Control), that is, more than 80% of PCBs were found to have oil leakage problems through naked eye observation and needed to be reworked or scrapped. The defective rate of the finished product AVI (Automated Visual Inspection) using FQC (Final Quality Control) was also more than 10%, that is, all PCB finished products were subjected to automatic visual inspection and found to still have more than 10% of PCBs with oil leakage problems and could not pass the final inspection. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a process for processing a solder mask single-sided window plugging plate, comprising:

[0006] A. Drill via holes on the copper clad board and lay out the metal copper layer in the via holes;

[0007] B. Prepare an aluminum mesh with holes according to the circuit design requirements. The diameter of the holes on the aluminum mesh is 0.1mm smaller than the diameter of the holes that need to be plugged in the circuit design. Align the aluminum mesh with the corresponding holes of the circuit board to ensure that the solder mask ink can accurately fill the holes without overflowing to other areas where there should be no solder mask material.

[0008] C. Use screen printing technology to fill the vias that do not need to be soldered with solder mask plugging ink with a viscosity of 300-400PS from the non-single-sided window surface of the copper clad laminate, and then use ordinary solder mask ink to print the non-single-sided window surface first and then the single-sided window surface; the solder mask plugging ink with a viscosity range of 300-400PS can pass through the screen smoothly and ensure the effect of filling the holes;

[0009] D. Heat the copper clad laminate treated in step C to 65-75°C for 30-50 minutes to pre-cure the solder resist ink in the via holes and the solder resist ink on the copper clad laminate surface, and then cool it to room temperature;

[0010] E. Using film exposure method, transfer the circuit pattern to the copper clad board processed in step D;

[0011] F. Place the copper clad laminate treated in step E into the developer entrance with the single-sided window facing upward, and transport it into a developing cylinder with a hydraulic pressure of 20 to 35 Psi. Use a developer to remove the solder resist ink outside the via hole and the solder resist ink in the unexposed part. Keeping the hydraulic pressure of the developing cylinder at 20 to 35 Psi can ensure the development effect and prevent oil from plugging the hole; then continue to transport it to a water washing cylinder with a hydraulic pressure of 5 to 10 Psi, and rinse the remaining solder resist ink with a new developer. Keeping the hydraulic pressure of the water washing cylinder at 5 to 10 Psi can ensure the cleaning effect and ensure that the ink in the via hole remains stable. The hydraulic pressure of the water washing cylinder is smaller than that of the developing cylinder, which can also prevent the solder resist plugging hole ink from rushing out of the via hole. After multiple rinsings until the solder resist ink outside the via hole and the solder resist ink in the unexposed part are completely removed, rinse the residual developer and dissolved solder resist ink on the copper clad laminate with clean water, and finally take out the copper clad laminate and dry it naturally;

[0012] G. Use a high-temperature tunnel furnace to heat and cure the copper-clad laminate after step F for 1.5 to 2.5 hours in sections. The wind speed in the high-temperature tunnel furnace is set to 5 to 20 m / s. Too high a wind speed can easily cause a strong physical impact on the surface of the circuit board, which may cause the solder mask plug ink to be blown out of the hole or shifted. However, no wind can easily cause uneven heating of the circuit board.

[0013] Preferably, the solder mask plugging ink includes the following components in parts by weight: 23-27 parts of modified epoxy resin, 17.5-22.5 parts of epoxy modified acrylic emulsion, 10-20 parts of ethanol, 3-7 parts of butanone, 12-18 parts of fumed silica, 7-13 parts of calcium carbonate, 3-6 parts of color paste, 0.5-1.9 parts of benzophenone, 0.5-1.9 parts of organic bentonite, 0.5-1.5 parts of leveling agent, 0.5-1.5 parts of defoaming agent, and 0.5-1.7 parts of dispersant. Modified epoxy resin and epoxy-modified acrylic emulsion are selected because they have better compatibility with other components. Modified epoxy resin has high crosslinking density and good heat resistance, while epoxy-modified acrylic emulsion has good flexibility. The combination of the two can make the solder mask plug ink have better adhesion, chemical resistance and mechanical properties; the combination of fumed silica and calcium carbonate can make the ink more uniform and stable when filling the holes; the viscosity and fluidity of the system are adjusted by adjusting the ratio between ethanol, butanone and other components to ensure that the final system viscosity is within the range of 300-400PS.

[0014] Preferably, the preparation process of the modified epoxy resin comprises the following steps: adding 120.5 parts of dehydrated polytetrahydrofuran diol and 500 parts of 4,4'-diphenyl diisocyanate into a container, stirring evenly, heating to 80-85°C and reacting for 2-3 hours to generate an isocyanate-terminated polyurethane prepolymer, and then mixing 100 parts of the isocyanate-terminated polyurethane prepolymer, 36.2 parts of glycidol and 272-408 parts of anhydrous dichloromethane solvent, and reacting at 40-50°C for 3-4 hours under a nitrogen atmosphere to obtain the modified epoxy resin.

[0015] Preferably, the dehydrated polytetrahydrofuran diol is prepared by using desiccant anhydrous calcium chloride to absorb the moisture in the polytetrahydrofuran diol.

[0016] Preferably, the leveling agent is a silicone leveling agent or an acrylate leveling agent.

[0017] Preferably, the defoaming agent is a mineral oil defoaming agent.

[0018] Preferably, the dispersant is a polyurethane dispersant.

[0019] Preferably, the solder mask plugging ink preparation process includes the following steps: uniformly mixing the modified epoxy resin and epoxy modified acrylic emulsion in a container according to weight parts, then adding weight parts of ethanol and butanone, continuing to stir evenly, then sequentially adding weight parts of fumed silica, calcium carbonate, color paste, benzophenone, organic bentonite, leveling agent, defoamer and dispersant to fully stir evenly, finally filtering to remove impurities and particles, and testing the viscosity to ensure that the viscosity of the finished ink is within the range of 300-400PS. Preferably, the filtration includes primary filtration and secondary filtration, the mesh aperture used for primary filtration is 150μm to effectively remove most of the larger particles and impurities, and the mesh aperture used for secondary filtration is 75μm to remove finer particles. The choice of the mesh here will also significantly affect the viscosity of the finished ink. If the mesh aperture is too coarse, the particles and impurities cannot be effectively removed, and if the mesh aperture is too fine, it will affect the fluidity and viscosity of the finished ink.

[0020] Preferably, the heating and curing process in step G is specifically to first heat the solder resist in the via hole at 80-100°C for 40-60 minutes, then cool it to 40-50°C, then heat the solder resist in the via hole at 100-120°C for 20-30 minutes, then cool it to 40-50°C, and finally heat the solder resist in the via hole at 120-150°C for 30-60 minutes.

[0021] The beneficial effects are as follows: the present application solves the problem of oil leakage from the single-sided window opening position of the plugged hole by adjusting the viscosity parameters of the solder resist plugging ink, improving the development operation method, and using a high-temperature tunnel furnace device for segmented heating and curing; specifically, firstly, the present application uses the independently developed solder resist plugging ink to fill the conductive holes that do not require welding. The modified epoxy resin and epoxy-modified acrylic emulsion used in the solder resist plugging ink have good compatibility with other components, ensuring that the ink has good adhesion to the substrate. If the solder resist plugging ink has poor adhesion to the circuit board substrate, the ink is easy to fall off or be washed out after plugging the hole, resulting in oil leakage; the system is made to reach an ideal viscosity by adjusting the ratio between ethanol, butanone and other components. If the viscosity of the solder resist plugging ink is too low, the ink is easy to flow when plugging the hole and cannot be well fixed in the hole. It is easy to be washed out during the development or washing process, resulting in oil leakage; if the viscosity of the solder resist plugging ink is too high, it may make it difficult for the ink to fully fill the hole, forming gaps or bubbles, which will also affect the sealing of the hole, leading to oil leakage. Other auxiliary ingredients can ensure that the ink has appropriate rheology and good chemical resistance. Too strong rheology may cause the ink to overflow when plugging the hole, while insufficient rheology may cause the ink to fail to fully fill the hole; poor chemical resistance may cause the solder mask plugging ink to be dissolved or corroded during the development process, causing the ink to be flushed out of the hole; secondly, during development, the hydraulic pressure of the developing cylinder is maintained at 20-35Psi, which can ensure the development effect and avoid oiling from the plugging hole; the hydraulic pressure of the water washing cylinder is maintained at 5-10Psi, which can ensure the cleaning effect and ensure that the ink in the via hole remains stable, and the hydraulic pressure of the water washing cylinder is smaller than that of the developing cylinder, which can also prevent the solder mask plugging ink from rushing out of the via hole, so that the copper clad laminate can smoothly transition from the developing cylinder to the water washing cylinder; finally, in step G, a segmented heating and curing method is used to ensure that the ink is uniformly and completely cured, reduce thermal stress and bubbles, and enhance the adhesion of the ink, thereby improving the processing quality and reliability of the circuit board; adding a breeze in the high-temperature tunnel furnace can both heat the circuit board evenly and avoid oiling from the plugging hole. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can understand the present invention more clearly.

[0023] The following embodiments are only used to illustrate the present invention, but are not limited to the scope of the present invention. Based on the specific embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work belong to the protection scope of the present invention.

[0024] In the examples of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the examples of the present invention, unless otherwise specified, the technical means used are conventional means well known to those skilled in the art.

[0025] Source of raw materials:

[0026] Ordinary solder resist ink, purchased from Guangzhou Weiqiao New Materials Co., Ltd.;

[0027] The developer was purchased from Shenzhen Baoxin Chemical Technology Co., Ltd.

[0028] Epoxy-modified acrylic emulsion was purchased from Shandong Suihua Biotechnology Co., Ltd.;

[0029] Butanone was purchased from Shandong Mantanghong New Materials Co., Ltd.

[0030] Fumed silica was purchased from Hubei Huifu Nanomaterials Co., Ltd.

[0031] Calcium carbonate was purchased from Nanyang Jinbo Mining Co., Ltd.

[0032] Benzophenone was purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.;

[0033] Organic bentonite was purchased from Henan Tianchou Chemical Products Co., Ltd.;

[0034] Organic silicon leveling agents BYK-300, BYK-306 and polyurethane dispersant DISPERBYK-190 were purchased from Shenzhen Longdi Chemical Co., Ltd.;

[0035] Acrylic leveling agent BYK-331 and mineral oil defoamer BYK-141 were purchased from Shanghai Kaiyin Chemical Co., Ltd.

[0036] The remaining reagents are commercially available.

[0037] Example 1

[0038] A process for processing a solder resist single-sided window plugging plate, comprising:

[0039] A. Drill via holes on the copper clad board and lay out the metal copper layer in the via holes;

[0040] B. Prepare an aluminum mesh with holes according to the circuit design requirements. The diameter of the holes on the aluminum mesh is 0.1mm smaller than the diameter of the holes that need to be plugged in the circuit design. Align the aluminum mesh with the corresponding holes on the circuit board.

[0041] C. Use screen printing technology to fill the vias that do not need to be soldered with solder mask plugging ink with a viscosity of 300-400PS from the non-single-sided window surface of the copper clad laminate, and then use ordinary solder mask ink to print the non-single-sided window surface first and then the single-sided window surface;

[0042] D. Heat the copper clad laminate treated in step C to 65°C for 30 minutes to pre-cure the solder resist ink in the via holes and the solder resist ink on the copper clad laminate surface, and then cool it to room temperature;

[0043] E. Using film exposure method, transfer the circuit pattern to the copper clad board processed in step D;

[0044] F. Place the copper clad laminate treated in step E into the developer entrance with the single-sided window facing upward, and transport it into a developing cylinder with a hydraulic pressure of 20 Psi, and use a developer to remove the solder resist ink outside the via hole and the solder resist ink in the unexposed part; then continue to transport it to a water washing cylinder with a hydraulic pressure of 5 Psi, and rinse the remaining solder resist ink with a new developer. After multiple rinses until the solder resist ink outside the via hole and the solder resist ink in the unexposed part are completely removed, rinse the remaining developer and dissolved solder resist ink on the copper clad laminate with clean water, and finally take out the copper clad laminate and let it dry naturally;

[0045] G. Use a high-temperature tunnel furnace device to heat and cure the copper-clad laminate after step F for 1.5 hours in sections. The specific heating and curing process is to first heat the solder resist in the via hole at 80°C for 40 minutes, then cool it to 40°C, then heat the solder resist in the via hole at 100°C for 20 minutes, then cool it to 40°C, and finally heat the solder resist in the via hole at 120°C for 30 minutes. The wind speed in the high-temperature tunnel furnace is set to 5m / s;

[0046] The solder mask plugging ink used in step C includes the following components by weight: 23 parts of modified epoxy resin, 22.5 parts of epoxy modified acrylic emulsion, 20 parts of ethanol, 7 parts of butanone, 12 parts of fumed silica, 7 parts of calcium carbonate, 6 parts of color paste, 0.5 parts of benzophenone, 0.5 parts of organic bentonite, 0.5 parts of organic silicone leveling agent (model BYK-300), 0.5 parts of mineral oil defoamer (model BYK-141), and 0.5 parts of polyurethane dispersant (model DISPERBYK-190); and the solder mask plugging ink is prepared according to the following steps:

[0047] Preparation of modified epoxy resin: 120.5 parts of dehydrated polytetrahydrofuran diol and 500 parts of 4,4'-diphenyl diisocyanate are added to a container, stirred evenly, and then heated to 80°C for reaction for 2 hours to generate a terminal isocyanate polyurethane prepolymer, and then 100 parts of the terminal isocyanate polyurethane prepolymer, 36.2 parts of propylene oxide and 272 parts of anhydrous dichloromethane solvent are mixed, and reacted at 40°C for 3 hours under a nitrogen atmosphere to obtain a modified epoxy resin; wherein the dehydrated polytetrahydrofuran diol is prepared by using a desiccant anhydrous calcium chloride to absorb the moisture in the polytetrahydrofuran diol;

[0048] The modified epoxy resin and epoxy-modified acrylic emulsion are mixed uniformly in a container according to the above-mentioned weight portions, and then the above-mentioned weight portions of ethanol and butanone are added, and the stirring is continued to be uniform. Then the above-mentioned weight portions of fumed silica, calcium carbonate, color paste, benzophenone, organic bentonite, leveling agent, defoaming agent and dispersant are added in sequence and fully stirred. Finally, impurities and particles are removed by filtration, wherein the filtration includes two steps of primary filtration and secondary filtration. The mesh aperture of the primary filtration is 150 μm, and the mesh aperture of the secondary filtration is 75 μm. The viscosity is tested to ensure that the viscosity of the finished ink is within the range of 300 to 400 PS.

[0049] Example 2

[0050] A process for processing a solder resist single-sided window plugging plate, comprising:

[0051] A. Drill via holes on the copper clad board and lay out the metal copper layer in the via holes;

[0052] B. Prepare an aluminum mesh with holes according to the circuit design requirements. The diameter of the holes on the aluminum mesh is 0.1mm smaller than the diameter of the holes that need to be plugged in the circuit design. Align the aluminum mesh with the corresponding holes on the circuit board.

[0053] C. Use screen printing technology to fill the vias that do not need to be soldered with solder mask plugging ink with a viscosity of 300-400PS from the non-single-sided window surface of the copper clad laminate, and then use ordinary solder mask ink to print the non-single-sided window surface first and then the single-sided window surface;

[0054] D. Heat the copper clad laminate treated in step C to 70°C for 40 minutes to pre-cure the solder resist ink in the via holes and the solder resist ink on the copper clad laminate surface, and then cool it to room temperature;

[0055] E. Using film exposure method, transfer the circuit pattern to the copper clad board processed in step D;

[0056] F. Place the copper clad laminate treated in step E into the developer entrance with the single-sided window facing upward, and transport it into a developing cylinder with a hydraulic pressure of 30 Psi, and use a developer to remove the solder resist ink outside the via hole and the solder resist ink in the unexposed part; then continue to transport it to a water washing cylinder with a hydraulic pressure of 7 Psi, and rinse the remaining solder resist ink with a new developer. After multiple rinses until the solder resist ink outside the via hole and the solder resist ink in the unexposed part are completely removed, rinse the remaining developer and dissolved solder resist ink on the copper clad laminate with clean water, and finally take out the copper clad laminate and let it dry naturally;

[0057] G. Use a high-temperature tunnel furnace device to heat and cure the copper-clad laminate after step F for 2 hours in sections. The specific heating and curing process is to first heat the solder resist in the via hole at 90°C for 50 minutes, then cool it to 45°C, then heat the solder resist in the via hole at 110°C for 25 minutes, then cool it to 45°C, and finally heat the solder resist in the via hole at 135°C for 45 minutes. The wind speed in the high-temperature tunnel furnace is set to 12m / s;

[0058] The solder mask plugging ink used in step C includes the following components by weight: 25 parts of modified epoxy resin, 20 parts of epoxy modified acrylic emulsion, 15 parts of ethanol, 5 parts of butanone, 15 parts of fumed silica, 10 parts of calcium carbonate, 4.5 parts of color paste, 1.2 parts of benzophenone, 1.2 parts of organic bentonite, 1 part of organic silicone leveling agent (model BYK-306), 1 part of mineral oil defoamer (model BYK-141), and 1.1 parts of polyurethane dispersant (model DISPERBYK-190); and the solder mask plugging ink is prepared according to the following steps:

[0059] Preparation of modified epoxy resin: add 120.5 parts of dehydrated polytetrahydrofuran diol and 500 parts of 4,4'-diphenyl diisocyanate into a container, stir evenly, heat to 83°C and react for 2.5 hours to generate terminal isocyanate polyurethane prepolymer, then mix 100 parts of terminal isocyanate polyurethane prepolymer, 36.2 parts of glycidol and 323 parts of anhydrous dichloromethane solvent, and react at 45°C for 3.5 hours under nitrogen atmosphere to obtain modified epoxy resin; wherein the dehydrated polytetrahydrofuran diol is prepared by using a desiccant anhydrous calcium chloride to absorb the moisture in the polytetrahydrofuran diol;

[0060] The modified epoxy resin and epoxy-modified acrylic emulsion are mixed uniformly in a container according to the above-mentioned weight portions, and then the above-mentioned weight portions of ethanol and butanone are added, and the stirring is continued to be uniform. Then the above-mentioned weight portions of fumed silica, calcium carbonate, color paste, benzophenone, organic bentonite, leveling agent, defoaming agent and dispersant are added in sequence and fully stirred. Finally, impurities and particles are removed by filtration, wherein the filtration includes two steps of primary filtration and secondary filtration. The mesh aperture of the primary filtration is 150 μm, and the mesh aperture of the secondary filtration is 75 μm. The viscosity is tested to ensure that the viscosity of the finished ink is within the range of 300 to 400 PS.

[0061] Example 3

[0062] A process for processing a solder resist single-sided window plugging plate, comprising:

[0063] A. Drill via holes on the copper clad board and lay out the metal copper layer in the via holes;

[0064] B. Prepare an aluminum mesh with holes according to the circuit design requirements. The diameter of the holes on the aluminum mesh is 0.1mm smaller than the diameter of the holes that need to be plugged in the circuit design. Align the aluminum mesh with the corresponding holes on the circuit board.

[0065] C. Use screen printing technology to fill the vias that do not need to be soldered with solder mask plugging ink with a viscosity of 300-400PS from the non-single-sided window surface of the copper clad laminate, and then use ordinary solder mask ink to print the non-single-sided window surface first and then the single-sided window surface;

[0066] D. Heat the copper clad laminate treated in step C to 75°C for 50 minutes to pre-cure the solder resist ink in the via holes and the solder resist ink on the copper clad laminate surface, and then cool it to room temperature;

[0067] E. Using film exposure method, transfer the circuit pattern to the copper clad board processed in step D;

[0068] F. Place the copper clad laminate treated in step E into the developer entrance with the single-sided window facing upward, and transport it into a developing cylinder with a hydraulic pressure of 35 Psi, and use a developer to remove the solder resist ink outside the via hole and the solder resist ink in the unexposed part; then continue to transport it to a water washing cylinder with a hydraulic pressure of 10 Psi, and rinse the remaining solder resist ink with a new developer. After multiple rinses until the solder resist ink outside the via hole and the solder resist ink in the unexposed part are completely removed, rinse the remaining developer and dissolved solder resist ink on the copper clad laminate with clean water, and finally take out the copper clad laminate and let it dry naturally;

[0069] G. Use a high-temperature tunnel furnace device to heat and cure the copper-clad laminate after step F for 2.5 hours in sections. The specific heating and curing process is to first heat the solder resist in the via hole at 100°C for 60 minutes, then cool it to 50°C, then heat the solder resist in the via hole at 120°C for 30 minutes, then cool it to 50°C, and finally heat the solder resist in the via hole at 150°C for 60 minutes. The wind speed in the high-temperature tunnel furnace is set to 20m / s;

[0070] The solder mask plugging ink used in step C includes the following components by weight: 27 parts of modified epoxy resin, 17.5 parts of epoxy modified acrylic emulsion, 10 parts of ethanol, 3 parts of butanone, 18 parts of fumed silica, 13 parts of calcium carbonate, 3 parts of color paste, 1.9 parts of benzophenone, 1.9 parts of organic bentonite, 1.5 parts of acrylate leveling agent (model BYK-331), 1.5 parts of mineral oil defoamer (model BYK-141), and 1.7 parts of polyurethane dispersant (model DISPERBYK-190); and the solder mask plugging ink is prepared according to the following steps:

[0071] Preparation of modified epoxy resin: 120.5 parts of dehydrated polytetrahydrofuran diol and 500 parts of 4,4'-diphenyl diisocyanate are added to a container, stirred evenly, and then heated to 85°C for reaction for 3 hours to generate a terminal isocyanate polyurethane prepolymer, and then 100 parts of the terminal isocyanate polyurethane prepolymer, 36.2 parts of propylene oxide and 408 parts of anhydrous dichloromethane solvent are mixed, and reacted at 50°C for 4 hours under a nitrogen atmosphere to obtain a modified epoxy resin; wherein the dehydrated polytetrahydrofuran diol is prepared by using a desiccant anhydrous calcium chloride to absorb the moisture in the polytetrahydrofuran diol;

[0072] The modified epoxy resin and epoxy-modified acrylic emulsion are mixed uniformly in a container according to the above-mentioned weight portions, and then the above-mentioned weight portions of ethanol and butanone are added, and the stirring is continued to be uniform. Then the above-mentioned weight portions of fumed silica, calcium carbonate, color paste, benzophenone, organic bentonite, leveling agent, defoaming agent and dispersant are added in sequence and fully stirred. Finally, impurities and particles are removed by filtration, wherein the filtration includes two steps of primary filtration and secondary filtration. The mesh aperture of the primary filtration is 150 μm, and the mesh aperture of the secondary filtration is 75 μm. The viscosity is tested to ensure that the viscosity of the finished ink is within the range of 300 to 400 PS.

[0073] Examples 1 to 3 were followed up with small batch tests, model: K2W11046A0, quantity 200PNL (each PNL=12PCS), board thickness 1.5mm, minimum via hole diameter 0.35mm; follow up on the oil leakage problem of single-sided window via holes during development, after development, PQC visually inspected all boards, no defective boards were found, the defect rate was 0 / 200=0%, the PQC visual inspection defect rate dropped from more than 80% to 0%, and the FQC finished product via hole full inspection defect rate was 2 / 200 / 12=0.08% (in this formula, 2 represents the number of defective products found during the inspection process; 200 represents the number of PCBs inspected in each batch; 12 represents that a total of 12 batches were inspected);

[0074] After large-scale follow-up, model ①: K2W11046A0, quantity 1000PNL (each PNL=12PCS), board thickness 1.5mm, minimum via hole diameter 0.35mm; follow up on the problem of oil leakage in the single-sided window via holes during development, after development, PQC conducted a full visual inspection and found no defective boards, with a defect rate of 0 / 1000=0%; the defect rate of the full inspection of FQC finished product via holes was 6 / 1000 / 12=0.05%. Model ②: K2W14611B0, quantity 1200PNL (each PNL = 16PCS), board thickness 1.5mm, minimum via hole diameter 0.30mm; follow up on the oil leakage problem of single-sided window via holes during development, PQC visually inspected after development, no defective boards were found, and the defect rate was 0 / 1200 = 0%; the defect rate of FQC finished product via hole full inspection was 10 / 1200 / 16 = 0.05% (in this formula, 10 represents the number of defective products found during the inspection process; 1200 represents the number of PCBs inspected in each batch; 16 represents a total of 16 batches inspected);

[0075] Experiments have shown that after the processing technology has been improved, the PQC visual inspection defect rate of oil oozing from the developed single-sided windowed via holes has dropped from over 80% to 0%, and the FQC finished product AVI full inspection defect rate has dropped from over 10% to 0.05%, which significantly improves the oil oozing from the plugged single-sided windowed via holes and reduces the rework and repair cost of the solder mask.

[0076] The above is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A process for processing a solder mask single-sided window plugging plate, characterized in that: include: A. Drill via holes on the copper clad board and lay out the metal copper layer in the via holes; B. Prepare an aluminum mesh with holes according to the circuit design requirements. The diameter of the holes on the aluminum mesh is 0.1 mm smaller than the diameter of the holes that need to be plugged in the circuit design. Align the aluminum mesh with the corresponding holes of the circuit board; C. Using screen printing technology, fill the vias that do not need to be soldered with solder resist plugging ink with a viscosity of 300-400PS from the non-single-sided window surface of the copper clad laminate, and then use ordinary solder resist ink to print the non-single-sided window surface first and then print the single-sided window surface; D. heating the copper clad laminate treated in step C to 65-75° C. and maintaining the temperature for 30-50 min to pre-cure the solder resist ink in the via holes and the solder resist ink on the copper clad laminate surface, and then cooling the copper clad laminate to room temperature; E. Using a film exposure method, transferring the circuit pattern to the copper-clad board processed in step D; F. Place the copper clad laminate treated in step E into the developer entrance with the single-sided window facing upward, and transport it into a developing cylinder with a hydraulic pressure of 20 to 35 Psi, and use a developer to remove the solder resist ink outside the via hole and the solder resist ink in the unexposed part; then continue to transport it to a water washing cylinder with a hydraulic pressure of 5 to 10 Psi, and rinse the remaining solder resist ink with a new developer. After multiple rinses until the solder resist ink outside the via hole and the solder resist ink in the unexposed part are completely removed, rinse the remaining developer and dissolved solder resist ink on the copper clad laminate with clean water, and finally take out the copper clad laminate and dry it naturally; G. Use a high-temperature tunnel furnace device to heat and cure the copper-clad laminate treated in step F in sections for 1.5 to 2.5 hours, and the wind speed in the high-temperature tunnel furnace is set to 5 to 20 m / s.

2. The process for processing a solder resist single-sided window plugging plate according to claim 1, characterized in that: The solder resist plugging ink comprises the following components in parts by weight: 23 to 27 parts of modified epoxy resin, 17.5 to 22.5 parts of epoxy modified acrylic emulsion, 10 to 20 parts of ethanol, 3 to 7 parts of butanone, 12 to 18 parts of fumed silica, 7 to 13 parts of calcium carbonate, 3 to 6 parts of color paste, 0.5 to 1.9 parts of benzophenone, 0.5 to 1.9 parts of organic bentonite, 0.5 to 1.5 parts of leveling agent, 0.5 to 1.5 parts of defoaming agent, and 0.5 to 1.7 parts of dispersant.

3. The process for processing a solder resist single-sided window plugging plate according to claim 2, characterized in that: The modified epoxy resin preparation process The method comprises the following steps: adding 120.5 parts of dehydrated polytetrahydrofuran diol and 500 parts of 4,4'-diphenyl diisocyanate into a container, stirring evenly, heating to 80-85°C for reaction for 2-3 hours to generate a terminal isocyanate polyurethane prepolymer, and then mixing 100 parts of the terminal isocyanate polyurethane prepolymer, 36.2 parts of glycidol and 272-408 parts of anhydrous dichloromethane solvent, and reacting at 40-50°C for 3-4 hours under a nitrogen atmosphere to obtain a modified epoxy resin.

4. The process for processing a solder resist single-sided window plugging plate according to claim 3, characterized in that: The dehydrated polytetrahydrofuran diol is prepared by using desiccant anhydrous calcium chloride to absorb the moisture in the polytetrahydrofuran diol.

5. The process for processing a solder resist single-sided window plugging plate according to claim 2, characterized in that: The leveling agent is selected from silicone leveling agent or acrylate leveling agent.

6. The process for processing a solder resist single-sided window plugging plate according to claim 2, characterized in that: The defoamer is a mineral oil defoamer.

7. The process for processing a solder resist single-sided window plugging plate according to claim 2, characterized in that: The dispersant is a polyurethane dispersant.

8. The process for processing a solder resist single-sided window plugging plate according to claim 1, characterized in that: The solder mask plugging ink preparation process comprises the following steps: uniformly mixing the modified epoxy resin and the epoxy modified acrylic emulsion in a container according to the weight proportions, then adding the weight proportions of ethanol and butanone, continuing to stir uniformly, then sequentially adding the weight proportions of fumed silica, calcium carbonate, color paste, benzophenone, organic bentonite, leveling agent, defoamer and dispersant, stirring fully and uniformly, finally filtering to remove impurities and particles, and testing the viscosity to ensure that the viscosity of the prepared finished ink is within the range of 300 to 400 PS.

9. The process for processing a solder resist single-sided window plugging plate according to claim 8, characterized in that: The filtration includes primary filtration and secondary filtration. The mesh aperture used in the primary filtration is 150 μm, and the mesh aperture used in the secondary filtration is 75 μm.

10. The process for processing a solder resist single-sided window plugging plate according to claim 1, characterized in that: The heating and curing process in step G is specifically as follows: first, the solder resist in the via hole is heated at 80-100°C for 40-60 minutes, then cooled to 40-50°C, then heated at 100-120°C for 20-30 minutes, then cooled to 40-50°C, and finally heated at 120-150°C for 30-60 minutes.