High-resolution photoresist composition for PCB (printed circuit board) solder resist ink process

Abstract

The invention provides a high-resolution photoresist composition for a PCB (printed circuit board) solder resist ink process, which belongs to the technical field of solder resist ink and comprises the following raw materials in percentage by weight: 10-55% of self-synthesized acrylic resin, 5-20% of cross-linking agent, 1-10% of photoinitiator, 1-20% of filler, 0.01-5% of dye and 5-35% of organic solvent. The invention provides a high-resolution photoresist composition for a PCB (Printed Circuit Board) solder resist ink process, which realizes the purpose of preparing high-resolution solder resist ink.

Description

Technical Field

[0001] The invention relates to the technical field of solder resist ink, and in particular to a high-resolution photoresist composition for a PCB solder resist ink process. Background Art

[0002] Solder mask ink plays an important role in the production of printed circuit boards (PCBs). It is a chemical mixture. The cured film can form a permanent protective layer on the surface of the printed circuit board to prevent the conductors and conductive patterns of the printed circuit board from being corroded by external forces or environmental factors (such as water, chemicals, etc.). Solder mask ink has two types: thermal curing and UV light curing, depending on the curing method. It is suitable for different types of PCB boards, such as hard boards, soft boards and aluminum substrates. PCB solder mask ink is currently a very large-volume ink in the world. The solder mask ink market is widely distributed, mainly concentrated in the Asia-Pacific region, North America and Europe. These regions have developed electronic industries and have a stable and continuous demand for solder mask ink products.

[0003] The development history of solder mask ink is closely related to equipment technology, welding conditions and circuit requirements. With the further high density of PCB and the emergence of lead-free soldering technology, new requirements are put forward for solder mask ink.

[0004] In particular, the demand for high-resolution solder mask ink is more urgent. However, at present, the domestic production of PCB solder mask ink is mainly low-end products, and high-resolution products still rely mainly on imports. Summary of the invention

[0005] In view of this, the present invention provides a high-resolution photoresist composition for PCB solder resist ink process to achieve the purpose of preparing high-resolution solder resist ink.

[0006] To achieve the above-mentioned purpose, the present invention provides a high-resolution photoresist composition for PCB solder mask ink process, comprising the following raw materials in weight percentage: 10-55% of independently synthesized acrylic resin, 5-20% of cross-linking agent, 1-10% of photoinitiator, 1-20% of filler, 0.01-5% of dye, and 5-35% of organic solvent.

[0007] Optionally, the preparation of the self-synthesized acrylic resin includes the following steps: acrylic acid, ethyl acrylate, hydroxypropyl methacrylate and 4-vinylbenzyl 2-methyl-2-acrylate are mixed evenly, and then subjected to constant temperature reaction in a continuous flow reaction device and then kept warm to obtain the self-synthesized acrylic resin.

[0008] The acrylic resin synthesized by the traditional kettle mechanical stirring process generally requires two steps. The first step is to open the double bonds of each monomer through an initiator and polymerize into a copolymer similar to the "ABCD" structure, in which the monomer generally contains a carboxyl structure that provides alkali tolerance and a benzene ring structure that provides corrosion resistance and hardness. However, due to the fact that the acrylic resin synthesized by the traditional kettle mechanical stirring process has a large molecular weight distribution coefficient (PDI) due to the inability of various monomers to fully react, the molecular weight is difficult to accurately control. If the resin is used in a solder mask ink system, the contrast of the ink system will be very low, that is, it is difficult to withstand the alkaline developer, resulting in the generation of floating glue, which will eventually seriously affect the performance of the solder mask ink. Therefore, the resin synthesized by the traditional mechanical stirring will be double-bonded on the basis of the copolymer produced in the first step, that is, glycidyl methacrylate (GMA) will react with the product of the first step. In this step of the reaction, the acid value of the resin will be reduced, thereby affecting the alkali solubility of the overall formula of the solder mask ink, so that the unexposed area cannot be dissolved in the alkaline developer in a short time, resulting in a very low resolution of the overall formula. At the same time, small molecules will be produced during the second step of the reaction.

[0009] The self-synthesized acrylic resin used in the present invention is a copolymer synthesized from acrylic acid, ethyl acrylate, hydroxypropyl methacrylate and 4-vinylbenzyl 2-methyl-2-acrylate. The molecular weight distribution coefficient (PDI) of the resin synthesized by a continuous flow reaction device is small, which ensures the uniformity of the resin molecular weight. At the same time, the reaction time and reaction temperature are controlled to increase the molecular weight of the resin. The contrast of the solder mask ink formula formed by compounding the resin synthesized by the continuous flow process with a cross-linking agent, an initiator, etc. can be greatly improved. Therefore, there is no need to introduce double bonds, and the second step reaction can be omitted. Therefore, the acid value of the resin will not decrease, and the unexposed area will quickly dissolve in the alkaline developer, ultimately greatly improving the resolution of the formula.

[0010] Optionally, the weight ratio of acrylic acid: ethyl acrylate: hydroxypropyl methacrylate: 4-vinylbenzyl 2-methyl-2-acrylate is 90-110:20-40:20-30:30-50.

[0011] Optionally, the isothermal reaction conditions include a temperature of 80-90° C. and a time of 1-1.5 h; and the insulation time is 0.5-1 h.

[0012] Optionally, the cross-linking agent is one or a combination of two or more of hydroxyethyl methacrylate HEMA, 1,6-hexanediol diacrylate HDDA, trimethylolpropane acrylate TMPTA, and glycidyl methacrylate GMA.

[0013] Optionally, the photoinitiator is one of photoinitiator 651, photoinitiator ITX, photoinitiator 907, Irgacure 127, photoinitiator 379, and photoinitiator 819, or a combination of two or more thereof.

[0014] Optionally, the dye is an anthraquinone-type environmentally friendly dye.

[0015] Optionally, the filler is barium sulfate.

[0016] Optionally, the organic solvent is acetone.

[0017] The above technical solution of the present invention includes at least the following beneficial effects: The technical solution provided by the present invention uses an independently synthesized acrylic resin and adopts a continuous flow reaction device. Compared with the acrylic resin synthesized by the conventional kettle mechanical stirring process in the prior art, the large-scale equipment investment and manpower expenditure are reduced, and the production cost of the acrylic resin is reduced, thereby reducing the cost of the high-resolution photoresist composition. At the same time, the acid value of the independently synthesized acrylic resin of the present invention is highly controllable, and the molecular weight distribution coefficient (PDI) is good, so that the relative dissolution rate (ADR) of the photoresist composition for the solder mask ink process formed can be adjusted in a large adjustable range, and the contrast of the photoresist composition is high, and finally the purpose of high resolution is achieved.

[0018] The high-resolution photoresist composition for PCB solder mask ink process provided by the present invention can clearly distinguish the minimum distance between two adjacent objects or features of 20 μm at a film thickness of 20 μm, that is, the resolution can reach 20 μm. The resolution of the 20 μm film thickness solder mask ink of Japan Sun Ink (PSR-4000 AUS308), a high-end product benchmark in the PCB solder mask ink industry in the prior art, is 40 μm, that is, the resolution of the product provided by the present invention is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A scanning electron microscope cross-sectional view of the high-resolution photoresist composition Startech solder resist ink SUN-5200N for PCB solder resist ink process prepared in Example 4 of the present invention; Figure 2 This is a scanning electron microscope cross-sectional view of the high-resolution photoresist composition Japan Taiyo Ink PSR-4000 for PCB solder mask ink process prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0020] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the following will be combined with the appended drawings of the embodiments of the present invention. Figure 1~2, the technical scheme of the embodiment of the present invention is clearly and completely described. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0021] Example 1 The preparation of the independently synthesized acrylic resin includes the following steps: 100g of acrylic acid, 20g of ethyl acrylate, 20g of hydroxypropyl methacrylate and 40g of 2-methyl-2-acrylate 4-vinylbenzyl ester are mixed evenly, and a constant temperature of 85°C is maintained for 1h through a continuous flow reaction device, and then the temperature is kept for 1h to obtain the independently synthesized acrylic resin.

[0022] Example 2 The preparation of the independently synthesized acrylic resin includes the following steps: 110g of acrylic acid, 30g of ethyl acrylate, 30g of hydroxypropyl methacrylate and 30g of 2-methyl-2-acrylate 4-vinylbenzyl ester are mixed evenly, and a constant temperature reaction of 90°C is maintained for 1.5h through a continuous flow reaction device, and then the temperature is kept for 0.5h to obtain the independently synthesized acrylic resin.

[0023] Example 3 The preparation of the independently synthesized acrylic resin includes the following steps: 90g of acrylic acid, 40g of ethyl acrylate, 20g of hydroxypropyl methacrylate and 50g of 2-methyl-2-acrylate 4-vinylbenzyl ester are mixed evenly, and a constant temperature of 80°C is maintained through a continuous flow reaction device for reaction for 1h and then kept warm for 0.5h to obtain the independently synthesized acrylic resin.

[0024] Example 4 A high-resolution photoresist composition for PCB solder mask ink process, comprising 180 g of the self-synthesized acrylic resin prepared in Example 1; 20 g of cross-linking agents hydroxyethyl methacrylate (HEMA), 1,6-hexanediol diacrylate (HDDA), and trimethylolpropane acrylate (TMPTA); 20 g of photoinitiator 651, photoinitiator ITX, and photoinitiator 907; 0.2 g of anthraquinone-type environmentally friendly dye; 6.2 g of barium sulfate; and 106 g of organic solvent acetone.

[0025] The above components were mixed and fully dissolved before filtering through a 0.2 μm filter to obtain a photoresist solution. The photoresist solution was spin-coated on the purified copper-clad laminate substrate and baked in an oven at 75°C for 15 minutes. The film thickness was measured to be about 20 μm. UV exposure, exposure dose 250-300 mJ / cm 2. The developed wafer was fixed with deionized water and then baked in an oven at 150°C for 55 minutes. The detection resolution was 20μm. Figure 1 .

[0026] Example 5 A high-resolution photoresist composition for PCB solder mask ink process, comprising 190 g of the self-synthesized acrylic resin prepared in Example 2; 30 g of cross-linking agents trimethylolpropane acrylate TMPTA and glycidyl methacrylate GMA; 20 g of Irgacure 127, photoinitiator 379 and photoinitiator 819; 1.2 g of anthraquinone-type environmentally friendly dye; 8 g of barium sulfate; and 100 g of an organic solvent acetone.

[0027] The above components were mixed and fully dissolved before filtering through a 0.2 μm filter to obtain a photoresist solution. The photoresist solution was spin-coated on the purified copper-clad laminate substrate and baked in an oven at 75°C for 15 minutes. The film thickness was measured to be about 20 μm. UV exposure, exposure dose 250-300 mJ / cm 2 . The image was developed with an alkaline solvent at a temperature of 30°C for 60 seconds. The developed silicon wafer was fixed with deionized water and then post-baked in an oven at 150°C for 55 minutes. The detection resolution was 20μm.

[0028] Example 6 A high-resolution photoresist composition for PCB solder mask ink process, comprising 200 g of the self-synthesized acrylic resin prepared in Example 3; 40 g of cross-linking agents 1,6-hexanediol diacrylate (HDDA) and trimethylolpropane acrylate (TMPTA); 30 g of photoinitiators ITX, 907 and Irgacure 127; 2 g of anthraquinone-type environmentally friendly dye; 10 g of barium sulfate; and 110 g of an organic solvent acetone.

[0029] The above components were mixed and fully dissolved before filtering through a 0.2 μm filter to obtain a photoresist solution. The photoresist solution was spin-coated on the purified copper-clad laminate substrate and baked in an oven at 75°C for 15 minutes. The film thickness was measured to be about 20 μm. UV exposure, exposure dose 250-300 mJ / cm 2 . The image was developed with an alkaline solvent at a temperature of 30°C for 60 seconds. The developed silicon wafer was fixed with deionized water and then post-baked in an oven at 150°C for 55 minutes. The detection resolution was 20μm.

[0030] Comparative Example 1 The high-resolution photoresist composition used in the prior art PCB solder mask ink process is obtained by taking the commercially available Japanese Taiyo ink (PSR-4000 AUS308): Component A, 80g: Component B, 20g; the above components are mixed, fully dissolved and filtered through a 0.2μm filter to obtain a photoresist solution. The photoresist solution is spin-coated on a purified silicon wafer substrate and baked in a 75℃ oven for 15 minutes. The film thickness is measured to be about 20μm. UV i-ray exposure, exposure dose 250-300mJ / cm 2 . The developed wafer was developed with an alkaline solvent at a temperature of 30°C and a development time of 60 seconds. The developed wafer was fixed with deionized water and then post-baked in an oven at 150°C for 55 minutes. The detection resolution was 40 μm. Figure 2 .

[0031] The performance of the high-resolution photoresist composition for PCB solder mask ink process prepared in Examples 4 to 6 and Comparative Example 1 was tested and the results are shown in Table 1.

[0032] Table 1 Performance table of products prepared in Examples 4 to 6 and Comparative Example 1

[0033] Combined with Table 1 Figure 1 , Figure 2 It can be seen that the high-resolution photoresist composition for PCB solder mask ink process prepared by the present invention has lower cost and higher resolution.

[0034] The above are preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A high-resolution photoresist composition for PCB solder mask ink process, characterized in that: The invention comprises the following raw materials in percentage by weight: 10-55% of self-synthesized acrylic resin, 5-20% of a cross-linking agent, 1-10% of a photoinitiator, 1-20% of a filler, 0.01-5% of a dye, and 5-35% of an organic solvent.

2. The high-resolution photoresist composition for PCB solder mask ink process according to claim 1, characterized in that: The preparation of the self-synthesized acrylic resin comprises the following steps: Acrylic acid, ethyl acrylate, hydroxypropyl methacrylate and 4-vinylbenzyl 2-methyl-2-acrylate are mixed evenly, reacted at a constant temperature in a continuous flow reaction device and then kept warm to obtain a self-synthesized acrylic resin.

3. The high-resolution photoresist composition for PCB solder mask ink process according to claim 2, characterized in that: The weight ratio of acrylic acid: ethyl acrylate: hydroxypropyl methacrylate: 2-methyl-2-acrylate 4-vinyl benzyl ester is 90-110: 20-40: 20-30: 30-50.

4. The high-resolution photoresist composition for PCB solder mask ink process according to claim 2, characterized in that: The isothermal reaction conditions include a temperature of 80-90° C. and a time of 1-1.5 h; and the insulation time is 0.5-1 h.

5. The high-resolution photoresist composition for PCB solder mask ink process according to claim 1, characterized in that: The crosslinking agent is one or a combination of two or more of hydroxyethyl methacrylate, 1,6-hexanediol diacrylate, trimethylolpropane acrylate, and glycidyl methacrylate.

6. The high-resolution photoresist composition for PCB solder mask ink process according to claim 1, characterized in that: The photoinitiator is one of photoinitiator 651, photoinitiator ITX, photoinitiator 907, Irgacure 127, photoinitiator 379, and photoinitiator 819, or a combination of two or more thereof.

7. The high-resolution photoresist composition for PCB solder mask ink process according to claim 1, characterized in that: The dye is an anthraquinone type environmentally friendly dye.

8. The high-resolution photoresist composition for PCB solder mask ink process according to claim 1, characterized in that: The filler is barium sulfate.

9. The high-resolution photoresist composition for PCB solder mask ink process according to claim 1, characterized in that: The organic solvent is acetone.

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