A photo-painted circuit board film

Abstract

The present invention provides a photo-drawn circuit board film, comprising a PET substrate. The back side of the PET substrate is provided with, from near to far, an adhesive antistatic layer, an anti-halation layer, and an anti-scratch frosted layer II. The film is characterized in that the front side of the PET substrate is provided with, from near to far, an adhesive layer, an absorbent layer, a transparent interlayer, a photosensitive layer, and an anti-scratch frosted layer I. This reduces the difference in line width and line spacing between the photo-drawn lines and the lines on the original circuit diagram, improves the smoothness of line edges, and enhances the line resolution of the photo-drawn circuit board film.

Description

Technical Field

[0001] The present invention relates to a photo-painted circuit board, in particular to a photo-painted circuit board film. Background Art

[0002] At present, there are two technical routes for the coating structure of photo-painted circuit board films, such as Figure 1 One method is to coat an anti-halation layer 6 on the back of a PET substrate 4 coated with adhesive layers on both sides, wherein the dye contained in the anti-halation layer is a water-soluble anti-halation dye that can be reduced to colorless in a fixing solution, and a photosensitive layer 2 and an anti-scratch and wear-resistant layer 1 are coated on the front side; Figure 1 From top to bottom, the film consists of an anti-scratch matte layer I1, a photosensitive layer 2, an adhesive layer 3, a PET substrate or polyester support 4, an adhesive antistatic layer 5, an anti-halation layer 6, and an anti-scratch matte layer II7. In this method, the back anti-halation layer 6 can only absorb the excess light passing through the PET, but cannot absorb the diffusely reflected light at the PET interface. The diffusely reflected light re-enters the photosensitive layer 2, causing the photosensitive layer 2 to be exposed twice, and the exposure area is expanded, resulting in rough edges of the photo-drawn lines, wider lines, narrower line spacing, and reduced line resolution. Currently, Fuji, Agfa, and Huaguang use this technical route. Another route is Figure 2 As shown, an anti-halation layer 8 is first applied on the top of a PET substrate 4 coated with adhesive layers 3 and 9 on both sides. The dye used in the anti-halation layer 8 is a water-insoluble pigment that can be reduced to colorless in a fixing solution. The back of the PET substrate 4 is coated with an adhesive layer 9 and an antistatic layer 10, but no anti-halation layer is applied. This method can absorb light diffusely reflected at the PET interface and obtain high-resolution lines. However, the water-insoluble anti-halation pigment used is protected by the company to which it belongs and is unavailable. Figure 2 The film comprises, from top to bottom, an anti-scratch matte layer Ⅰ1, a photosensitive layer 2, an anti-halation layer 8, an adhesive layer 3, a polyester support 4, an adhesive layer 9 and an antistatic layer 10. Summary of the Invention

[0003] To solve the above problems, the present invention provides a photo-drawn circuit board film, which reduces the difference between the line width and line spacing of the light-drawn lines and the lines of the original circuit diagram, improves the smoothness of the line edges, and enhances the line resolution of the photo-drawn circuit board film.

[0004] The object of the present invention is achieved in the following manner: a photo-painted circuit board film includes a PET substrate, the back side of the PET substrate is provided with an adhesive antistatic layer, an anti-halation layer and an anti-scratch frosted layer II in sequence from near to far, and is characterized in that the front side of the PET substrate is provided with an adhesive layer, an absorption layer, a transparent interlayer, a photosensitive layer and an anti-scratch frosted layer I in sequence from near to far.

[0005] The transparent interlayer is transparent and its main function is to prevent the water-soluble anti-halation dye in the absorbing layer from diffusing into the photosensitive layer due to the wetting effect when the photosensitive layer is coated on the absorbing layer in the absence of the interlayer, thereby reducing the sensitivity of the film and even generating fog.

[0006] The thickness of the transparent interlayer is 0.2um - 0.8um. ​​If it is too thick, it will affect the penetration rate of the fixing solution, while if it is too thin, the effect of blocking the diffusion of the dye in the absorbing layer will be weakened.

[0007] The interlayer coating liquid that is coated and dried to form a transparent interlayer does not contain any dye. Calculated by weight, the interlayer coating liquid contains 2%-4% gelatin, 0.01%-0.1% nonionic surfactant, 0.01%-0.1% anionic surfactant, 0.01%-0.1% pH regulator, 0.01%-0.05%, 0.02%-0.1% thickener, 0.001%-0.01% preservative, and the remainder is pure water.

[0008] The surfactant is a combination of a nonionic surfactant and an anionic surfactant, wherein the nonionic surfactant can be a fluorosurfactant, or can be a polyoxyethylene ether, a fatty acid polyoxyethylene ester, or a polyol, and the anionic surfactant can be a fatty acid salt, or a sulfonate.

[0009] The pH adjuster is mainly at least one of a weak acid, a weak base, a low-concentration strong acid or a low-concentration strong base, such as acetic acid, citric acid, ammonia water, sodium bicarbonate or a low-concentration sodium hydroxide.

[0010] The thickener can be sodium polyacrylate, sodium polystyrene sulfonate, polyvinyl pyrrolidone, or sodium carboxymethyl cellulose.

[0011] Preservatives can be sodium benzoate, phenol, potassium sorbate, butyl paraben, or isothiazolinone.

[0012] Do not add film hardeners to the transparent interlayer. Film hardeners can cross-link with gelatin, increasing the film's hardness, but the resulting cross-linked network is ineffective in blocking small-molecule dyes. Without film hardeners, gelatin's inherent irregular curling and fragmentation can effectively block the upward diffusion of water-soluble anti-halation dyes.

[0013] The thickness of the absorption layer is 0.5um-2um. If it is too thick, it will affect the penetration of the fixing solution, and if it is too thin, the water-soluble anti-halation dye will not be absorbed well.

[0014] Compared to the anti-halation layer coating solution used for coating and drying to form the absorbing layer, the absorbing layer coating solution used for coating and drying to form the anti-halation layer uses less water-soluble anti-halation dye and does not contain small molecule resin. Since the water-soluble anti-halation dye accounts for 0.04%-0.1% of the total, the amount of gelatin used is 1%-2% of the total. Furthermore, the resulting absorbing layer is thinner than the anti-halation layer.

[0015] In the absorption layer coating liquid, by weight percentage, the amount of water-soluble anti-halation dye accounts for 0.04%-0.1% of the total amount, the amount of gelatin accounts for 1%-2% of the total amount, the amount of non-ionic surfactant accounts for 0.01%-0.1% of the total amount, the amount of anionic surfactant accounts for 0.01%-0.1% of the total amount, the amount of penetrant accounts for 0.5%-2% of the total amount, the amount of thickener accounts for 0.02%-0.1% of the total amount, the amount of preservative accounts for 0.001%-0.01% of the total amount, and the rest is pure water.

[0016] The surfactant is a combination of a nonionic surfactant and an anionic surfactant, wherein the nonionic surfactant can be a fluorosurfactant, or can be a polyoxyethylene ether, a fatty acid polyoxyethylene ester, or a polyol; the anionic surfactant can be a fatty acid salt, or a sulfonate.

[0017] The penetrant can be fatty alcohol polyoxyethylene ether, sodium alkylbenzene sulfonate, or sodium alkylnaphthalene sulfonate.

[0018] The thickener is sodium polyacrylate, sodium polystyrene sulfonate, polyvinyl pyrrolidone, sodium carboxymethyl cellulose, etc.

[0019] Preservatives can be sodium benzoate, phenol, potassium sorbate, butyl paraben, or isothiazolinone.

[0020] The water-soluble anti-halation dye may be a pentamethine cyanine dye, or other polymethine cyanine dyes such as a heptamethine cyanine dye, or a cyanine dye, and the maximum absorption peak is between 630 nm and 680 nm.

[0021] The thickness of the anti-halation layer is 2-4um.

[0022] The anti-halation layer coating liquid that is coated and dried to form an anti-halation layer comprises, by weight percentage, 3%-7% of gelatin, 0.001%-0.01% of preservatives, 0.001%-0.01% of pH adjusters, 0.01%-0.1% of nonionic surfactants, 0.01%-0.1% of anionic surfactants, 0.1%-0.1% of anti-halation dyes, 0.01%-0.1% of thickeners, 1%-5% of small molecule resins, and the remainder being pure water.

[0023] The preservative is sodium benzoate, phenol, potassium sorbate, butyl parahydroxybenzoate or isothiazolinone; the film hardener is an inorganic film hardener or an organic film hardener; the pH adjuster can be a weak acid, a weak base or a low concentration of sodium hydroxide or potassium hydroxide; the non-ionic surfactant is a fluorosurfactant, polyoxyethylene ether, fatty acid polyoxyethylene ester or polyol; the anionic surfactant is a fatty acid salt or sulfonate; the thickener is sodium polyacrylate, sodium polystyrene sulfonate, polyvinyl pyrrolidone or sodium carboxymethyl cellulose; the water-soluble anti-halation dye is pentamethicone cyanine dye.

[0024] Compared to the prior art, the present invention, based on the first technical route, appropriately modifies the coating structure of the photo-drawing film, adding an absorption layer and a transparent interlayer. This utilizes existing water-soluble anti-halation dyes to absorb diffusely reflected light generated at the PET interface, preventing secondary exposure of the photosensitive layer. This reduces the difference in line width and spacing between the drawn lines and the original circuit diagram, improves line edge smoothness, and ultimately enhances the line resolution of the photo-drawn circuit board film. Conventionally, photo-drawing film using the first technical route, after photo-drawing, developing, fixing, and rinsing, has a line width significantly greater than the line spacing, and exhibits significant burrs along the line edges. This can easily lead to short circuits and resulting in scrap on high-end circuit boards, failing to meet the requirements of high-end photo-drawn circuit board production. Therefore, the minimum line width and spacing that can be drawn is 2 mils. However, by adding the absorption layer and transparent interlayer to the coating structure, the minimum line width and spacing for photo-drawn lines can be reduced to 1 mil, enabling the application of photo-drawn circuit board film in precision circuit board manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the structure of the existing light-drawn circuit board Figure 1 .

[0026] Figure 2 This is a schematic diagram of the structure of the existing light-painted circuit board film Figure 2 .

[0027] Figure 3 It is a structural schematic diagram of the photo-painted circuit board film of the present invention.

[0028] Figure 4 This is a line (1 mil) image of the photo-painted circuit board film of Comparative Example 1 after photo-painting, developing, fixing and washing.

[0029] Figure 5 This is a line image (1 mil) of the photo-painted circuit board film prepared in Example 1 after photo-painting, developing, fixing and washing.

[0030] Figure 6 This is a line image (1 mil) of the photo-painted circuit board film prepared in Example 2 after photo-painting, developing, fixing and washing. DETAILED DESCRIPTION

[0031] like Figure 3 As shown, the present invention provides a photo-painted circuit board film, including a PET substrate 4, the back of the PET substrate 4 is provided with an adhesive antistatic layer 5, an anti-halation layer 6 and an anti-scratch frosted layer II 7 in sequence from near to far, and the front of the PET substrate 4 is provided with an adhesive layer I3, an absorption layer 12, a transparent interlayer 11, a photosensitive layer 2, and an anti-scratch frosted layer I1 in sequence from near to far.

[0032] The thickness of the absorbing layer 12 is 0.5 μm to 2 μm. If it is too thick, it will affect the penetration of the fixing solution. If it is too thin, the water-soluble anti-halation dye in the absorbing layer 12 will not absorb light well.

[0033] The absorbing layer coating solution, which is applied and dried to form the absorbing layer 12, contains less water-soluble anti-halation dye than the anti-halation layer 6 and does not contain a small molecule resin. The water-soluble anti-halation dye accounts for 0.04% to 0.1% of the total amount, and the gelatin accounts for 1% to 2% of the total amount. Furthermore, the absorbing layer 12 formed is thinner than the anti-halation layer 6.

[0034] Specifically, in the coating liquid of the absorption layer 12, by weight percentage, the amount of water-soluble anti-halation dye accounts for 0.04%-0.1% of the total amount, the amount of gelatin accounts for 1%-2% of the total amount, the amount of non-ionic surfactant accounts for 0.01%-0.1% of the total amount, the amount of anionic surfactant accounts for 0.01%-0.1% of the total amount, the amount of penetrant accounts for 0.5%-2% of the total amount, the amount of thickener accounts for 0.02%-0.1% of the total amount, the amount of preservative accounts for 0.001%-0.01% of the total amount, and the rest is pure water.

[0035] The surfactant is a combination of a nonionic surfactant and an anionic surfactant, wherein the nonionic surfactant can be a fluorosurfactant, or can be a polyoxyethylene ether, a fatty acid polyoxyethylene ester, or a polyol; the anionic surfactant can be a fatty acid salt or a sulfonate, such as sodium dodecylbenzenesulfonate.

[0036] The penetrant can be fatty alcohol polyoxyethylene ether, sodium alkylbenzene sulfonate, or sodium alkylnaphthalene sulfonate.

[0037] The thickener is sodium polyacrylate, sodium polystyrene sulfonate, polyvinyl pyrrolidone, sodium carboxymethyl cellulose, etc.

[0038] The preservative may be sodium benzoate, phenol, potassium sorbate, butyl paraben or isothiazolinone.

[0039] The water-soluble anti-halation dye may be a pentamethine cyanine dye, or other polymethine cyanine dyes such as a heptamethine cyanine dye, or a cyanine dye, and the maximum absorption peak is between 630 nm and 680 nm.

[0040] The interlayer coating liquid that is applied and dried to form the transparent interlayer 11 does not contain any dye. By weight, the interlayer coating liquid comprises 2%-4% gelatin, 0.01%-0.1% nonionic surfactant, 0.01%-0.1% anionic surfactant, 0.01%-0.1% pH adjuster, 0.01%-0.05% thickener, 0.02%-0.1% preservative, and the remainder is pure water. Purified water in this application refers to deionized water.

[0041] The surfactant is a combination of a nonionic surfactant and an anionic surfactant, wherein the nonionic surfactant can be a fluorosurfactant, or can be a polyoxyethylene ether, a fatty acid polyoxyethylene ester, or a polyol; the anionic surfactant can be a fatty acid salt or a sulfonate, such as sodium dodecylbenzenesulfonate.

[0042] The pH regulator is mainly at least one of a weak acid, a weak base, a low concentration of a strong acid or a low concentration of a strong base, such as acetic acid, citric acid, ammonia water, sodium bicarbonate, a low concentration of sodium hydroxide, potassium hydroxide, such as low concentration of sodium hydroxide, potassium hydroxide, etc. obtained by adding sodium hydroxide, potassium hydroxide, etc.

[0043] The thickener is sodium polyacrylate, sodium polystyrene sulfonate, polyvinyl pyrrolidone, sodium carboxymethyl cellulose, etc.

[0044] Preservatives can be sodium benzoate, phenol, potassium sorbate, butyl paraben, or isothiazolinone.

[0045] No film hardeners should be added to the transparent interlayer 11. Film hardeners can cross-link with gelatin to increase the film's hardness, but the resulting cross-linked network does not block small-molecule dyes. Without a film hardener, gelatin's inherent irregular curling and fragmentation can effectively block the upward diffusion of water-soluble anti-halation dyes.

[0046] The absorption layer 12 and the transparent interlayer 11 can be dried naturally or by hot air drying at a temperature between 30° C. and 50° C.

[0047] The transparent interlayer 11 is transparent and mainly serves to prevent the water-soluble anti-halation dye in the absorbing layer 12 from diffusing into the photosensitive layer 2 due to the wetting effect when the photosensitive layer 2 is coated on the absorbing layer 12 in the absence of the transparent interlayer, thereby reducing the sensitivity of the film and even generating gray fog.

[0048] The thickness of the transparent interlayer 11 is 0.2 μm to 0.8 μm. If it is too thick, the penetration rate of the fixing solution will be affected, while if it is too thin, the diffusion effect of the water-soluble anti-halation dye in the blocking absorption layer 12 will be weakened.

[0049] In the coating liquid of the anti-halation layer 6, by weight percentage, the amount of gelatin accounts for 3%-7% of the total amount, the amount of preservative accounts for 0.001%-0.01% of the total amount, the amount of pH adjuster accounts for 0.001%-0.01% of the total amount, the amount of nonionic surfactant accounts for 0.01%-0.1% of the total amount, the amount of anionic surfactant accounts for 0.01%-0.1% of the total amount, the amount of anti-halation dye accounts for 0.1%-0.3% of the total amount, the amount of thickener accounts for 0.01%-0.1% of the total amount, the amount of small molecule resin accounts for 1%-5% of the total amount, and the rest is pure water.

[0050] The preservative may be sodium benzoate, phenol, potassium sorbate, butyl paraben or isothiazolinone.

[0051] The pH regulator can be a weak acid, such as acetic acid, citric acid, etc., or a weak base, such as sodium bicarbonate, low concentration sodium hydroxide, potassium hydroxide, such as low concentration sodium hydroxide, potassium hydroxide, etc. obtained by adding sodium hydroxide, potassium hydroxide, etc.

[0052] The surfactant is a combination of a nonionic surfactant and an anionic surfactant, wherein the nonionic surfactant can be a fluorosurfactant, or can be a polyoxyethylene ether, a fatty acid polyoxyethylene ester, or a polyol; the anionic surfactant can be a fatty acid salt or a sulfonate, such as sodium dodecylbenzenesulfonate.

[0053] The thickener can be sodium polyacrylate, sodium polystyrene sulfonate, polyvinyl pyrrolidone, or sodium carboxymethyl cellulose.

[0054] The water-soluble anti-halation dye may be a pentamethine cyanine dye, or other polymethine cyanine dyes such as a heptamethine cyanine dye, or a cyanine dye, and the maximum absorption peak is between 630 nm and 680 nm.

[0055] The small molecule resin may be a copolymer of vinyl acetate and acrylate, a copolymer of styrene and acrylate, or a copolymer of vinylidene chloride and acrylate.

[0056] According to prior art, the anti-halation layer 6 primarily functions as follows: 1. Absorbs excess light transmitted through the PET substrate 4, preventing a halo effect. 2. The anti-halation layer 6 contains a small molecule resin that reduces expansion and contraction of the film. The dry thickness of the anti-halation layer 6 is approximately 2-4 μm.

[0057] The coating liquid for forming the anti-scratch frosted layer II 7 is coated and dried. In the anti-scratch frosted coating liquid 7, the amount of gelatin accounts for 4%-8% of the total amount, the amount of the roughening agent accounts for 0.2%-1% of the total amount, the amount of the preservative accounts for 0.001%-0.01% of the total amount, the amount of the film hardening agent accounts for 0.05%-0.2% of the total amount, the amount of the pH regulator accounts for 0.001%-0.01% of the total amount, the amount of the nonionic surfactant accounts for 0.01%-0.1% of the total amount, the amount of the anionic surfactant accounts for 0.01%-0.1% of the total amount, and the rest is pure water.

[0058] The surface roughening agent can be micron-sized silicon dioxide particles or micron-sized PMMA powder. The particle size of the surface roughening agent is between 5-10um.

[0059] The preservative may be sodium benzoate, phenol, potassium sorbate, butyl paraben or isothiazolinone.

[0060] The film hardener may be an inorganic film hardener, such as chromium vanadium, glutaraldehyde, etc., or an organic film hardener, such as 1,3-bis(vinylsulfone)methane or 2,4-dichloro-6-hydroxy-s-triazine sodium salt.

[0061] The pH regulator can be a weak acid, such as acetic acid, citric acid, etc., or a weak base, such as sodium bicarbonate, low-concentration sodium hydroxide, potassium hydroxide, such as low-concentration sodium hydroxide, potassium hydroxide, etc., which can be obtained by adding sodium hydroxide, potassium hydroxide.

[0062] The surfactant is a combination of a nonionic surfactant and an anionic surfactant, wherein the nonionic surfactant can be a fluorosurfactant, or can be a polyoxyethylene ether, a fatty acid polyoxyethylene ester, or a polyol; the anionic surfactant can be a fatty acid salt or a sulfonate, such as sodium dodecylbenzenesulfonate.

[0063] The main functions of the scratch-resistant matte layer II7 are: 1. Protecting the anti-halation layer 6 from damage during storage, transportation, and use. 2. The scratch-resistant matte layer II7 contains a matte agent that increases the roughness of the anti-halation coating, making it easier to vacuum the film during use and ensuring a closer fit between the film and the copper-clad circuit board.

[0064] The coating liquid for forming the anti-scratch frosted layer Ⅰ1 by coating and drying is as follows: in the coating liquid for the anti-scratch frosted layer 1, the amount of gelatin accounts for 4%-8% of the total amount, the amount of the matting agent accounts for 0.2%-1% of the total amount, the amount of the preservative accounts for 0.001%-0.01% of the total amount, the amount of the film hardening agent accounts for 0.05%-0.2% of the total amount, the amount of the pH regulator accounts for 0.001%-0.01% of the total amount, the amount of the nonionic surfactant accounts for 0.01%-0.1% of the total amount, the amount of the anionic surfactant accounts for 0.01%-0.1% of the total amount, and the rest is pure water.

[0065] The surface roughening agent can be micron-sized silicon dioxide particles or micron-sized PMMA powder. The particle size of the surface roughening agent is between 2-5 μm.

[0066] Preservatives can be sodium benzoate, phenol, potassium sorbate, butyl paraben, or isothiazolinone.

[0067] The film hardener may be an inorganic film hardener, such as chromium vanadium, glutaraldehyde, etc., or an organic film hardener, such as 1,3-bis(vinylsulfone)methane or 2,4-dichloro-6-hydroxy-s-triazine sodium salt.

[0068] The pH regulator can be a weak acid, such as acetic acid, citric acid, etc., or a weak base, such as sodium bicarbonate, low-concentration sodium hydroxide, etc.

[0069] The surfactant is a combination of a nonionic surfactant and an anionic surfactant, wherein the nonionic surfactant can be a fluorosurfactant, or can be a polyoxyethylene ether, a fatty acid polyoxyethylene ester, or a polyol; the anionic surfactant can be a fatty acid salt or a sulfonate, such as sodium dodecylbenzenesulfonate.

[0070] The main function of the anti-scratch frosted layer I1 is to protect the photosensitive layer 2 from being damaged during storage, transportation and use.

[0071] In the coating liquid of the photosensitive layer 2, by weight percentage, the amount of gelatin accounts for 2%-5% of the total amount, the amount of unexposed nano-scale silver halide particles accounts for 5%-8% of the total amount, the amount of pH adjuster accounts for 0.001%-0.01% of the total amount, the amount of thickener accounts for 0.01%-0.1% of the total amount, the amount of small molecule resin accounts for 1%-5% of the total amount, the amount of antifoggant accounts for 0.001%-0.01% of the total amount, the amount of sensitizer accounts for 0.0001%-0.001% of the total amount, the amount of hardener accounts for 0.1%-0.5% of the total amount, and the rest is pure water.

[0072] The nanometer-scale silver halide particles can be silver chloride or a mixture of silver chloride and silver bromide. The particle size of the silver halide particles is between 100 and 300 nanometers and they are highly dispersed and uniform in the coating solution.

[0073] The pH regulator can be a weak acid, such as acetic acid, citric acid, etc., or a weak base, such as sodium bicarbonate, low-concentration sodium hydroxide, etc.

[0074] The thickener can be sodium polyacrylate, sodium polystyrene sulfonate, polyvinyl pyrrolidone, or sodium carboxymethyl cellulose.

[0075] The small molecule resin may be a copolymer of vinyl acetate and acrylate, a copolymer of styrene and acrylate, or a copolymer of vinylidene chloride and acrylate.

[0076] The anti-fogging agent may be benzotriazole, tetrazole, potassium bromide or a combination thereof.

[0077] The sensitizer can be a heavy metal salt such as gold salt, rhodium salt, etc., or it can be a sulfide such as sodium sulfide, sulfur, etc.

[0078] The film hardener can be an inorganic film hardener, such as chromium vanadium, or an organic film hardener, such as 1,3-bis(vinylsulfone)methane or 2,4-dichloro-6-hydroxy-s-triazine sodium salt.

[0079] In the coating liquid of the adhesive layer I3, by weight percentage, the adhesive accounts for 5%-20% of the total weight, the surfactant accounts for 0.5%-2% of the total weight, the film-forming agent accounts for 2%-5% of the total weight, and the rest is pure water.

[0080] The binder can be an aliphatic anionic modified waterborne polyurethane resin dispersion or a waterborne acrylic copolymer emulsion.

[0081] The surfactant can be a nonionic surfactant, such as a fluorosurfactant, polyoxyethylene ether, fatty acid polyoxyethylene ester or polyol; or it can be an anionic surfactant, fatty acid salt or sulfonate, such as sodium dodecylbenzenesulfonate.

[0082] The film-forming agent can be some copolymers, such as copolymers of vinyl acetate and acrylate, or copolymers of vinylidene chloride and acrylate.

[0083] In the coating liquid for bonding the antistatic layer 5, by weight percentage, the binder accounts for 5%-20% of the total weight, the surfactant accounts for 0.5%-2% of the total weight, the film-forming agent accounts for 2%-5% of the total weight, the antistatic agent accounts for 1%-5% of the total weight, and the rest is pure water.

[0084] The binder can be an aliphatic anionic modified waterborne polyurethane resin dispersion or a waterborne acrylic copolymer emulsion.

[0085] The surfactant can be a nonionic surfactant, such as a fluorosurfactant, polyoxyethylene ether, fatty acid polyoxyethylene ester or polyol; or it can be an anionic surfactant, fatty acid salt or sulfonate, such as sodium dodecylbenzenesulfonate.

[0086] The film-forming agent can be some copolymers, such as copolymers of vinyl acetate and acrylate, or copolymers of vinylidene chloride and acrylate.

[0087] The antistatic agent can be a water-based nonionic antistatic agent, can be ethoxylated lauryl amide, or glyceryl monostearate.

[0088] The drying temperature of the adhesive layer I3 and the adhesive antistatic layer 5 is between 100-120°C, and the drying temperature of the remaining layers is between 30-50°C, using hot air drying.

[0089] The original anti-halation layer 6 and anti-scratch matte layer 7 are retained on the back of the PET substrate coated with an adhesive layer. A transparent interlayer 11 and an absorption layer 12 are first applied beneath the adhesive layer on the front photosensitive layer 2. A small amount of water-soluble anti-halation dye is added to the absorption layer 12, which is the same dye as the anti-halation layer 6 on the back. When a laser light source illuminates the photosensitive layer 2, the light passes through the photosensitive layer 2 and the absorption layer 12 into the interior of the PET substrate 4, where it undergoes diffuse reflection and scattering on the surface and interior of the PET substrate 4. The anti-halation layer 6 on the back absorbs most of the scattered light, while the remaining small amount of reflected light is absorbed by the absorption layer 12. This prevents the reflected light from entering the photosensitive layer 2 and causing secondary exposure, which can widen the line width of the photo-painted lines and roughen the line edges, thereby improving the resolution of the photo-painted lines. Because water-soluble anti-halation dyes easily diffuse in a wet coating and diffuse into the photosensitive layer 2, which can reduce the film's sensitivity, the present invention includes a transparent interlayer 11 coated between the absorbing layer 12 and the photosensitive layer 2 to prevent the water-soluble anti-halation dyes from diffusing into the photosensitive layer 2. The absorbing layer 12 and the transparent interlayer 11 can be coated in a single layer or separately.

[0090] The water-soluble anti-halation dye may be a pentamethine cyanine dye, or other polymethine cyanine dyes such as a heptamethine cyanine dye, or a cyanine dye, and the maximum absorption peak is between 630 nm and 680 nm.

[0091] Compared to the prior art, the present invention, based on the first technical route, makes appropriate changes to the structure of the photo-drawing film, adding an absorption layer 12 and a transparent interlayer 11. This utilizes existing water-soluble anti-halation dyes to absorb diffusely reflected light generated at the PET interface, preventing secondary exposure of the photosensitive layer. This reduces the difference in line width and spacing between the drawn lines and the lines on the original circuit diagram, improves the smoothness of line edges, and achieves the goal of improving the line resolution of the photo-drawing circuit board film. The photo-drawing film typically uses the first technical route, which can produce a minimum line width and spacing of 2 mils. However, by adding the coating structure of the absorption layer and transparent interlayer, the minimum line width and spacing of the drawn lines can be reduced to 1 mil, enabling the application of the photo-drawing circuit board film in the manufacture of precision circuit boards.

[0092] The present invention is described in detail below with reference to specific embodiments. It is necessary to point out that this embodiment is only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art in this field can make some non-essential improvements and adjustments based on the contents of the present invention.

[0093] Specific example 1:

[0094] The composition of the absorption layer coating liquid, by weight percentage, is 0.07% of water-soluble pentamethicone cyanine dye, 2% of gelatin, the non-ionic surfactant is a fluorosurfactant, FC-202 produced by Guangzhou Chunyan Industrial Co., Ltd., with a usage of 0.02%; the anionic surfactant sodium dodecylbenzenesulfonate is 0.04%, the penetrant sodium alkyl succinate sulfonate is 0.9%, the thickener sodium polystyrene sulfonate is 0.08%, the preservative isothiazolinone is 0.002%, and the rest is pure water.

[0095] The composition of the transparent interlayer coating liquid is as follows: by weight percentage, gelatin is 2.6%, the non-ionic surfactant is a fluorosurfactant, FC-202 produced by Guangzhou Chunyan Industrial Co., Ltd., the usage is 0.015%; the anionic surfactant sodium dodecylbenzene sulfonate is 0.03%, the pH regulator citric acid is 0.012%, the thickener sodium polystyrene sulfonate is 0.05%, the preservative isothiazolinone is 0.0018%, and the rest is pure water.

[0096] The coating liquid composition of the photosensitive layer 2 is as follows: gelatin accounts for 3.2% of the total amount, unexposed nano-scale silver halide particles are composed of a mixture of silver chloride and silver bromide in a molar ratio of 4.1:1, accounting for 5.5% of the total amount, citric acid as a pH adjuster accounts for 0.0037% of the total amount, sodium polystyrene sulfonate as a thickener accounts for 0.04% of the total amount, the small molecule resin vinyl acetate and acrylate copolymer is Nipol LX552 latex produced by Japan Zeon Co., Ltd., accounting for 2.9% of the total amount, anti-fogging agent benzotriazole accounts for 0.004% of the total amount, sensitizer gold trichloride accounts for 0.00061% of the total amount, film hardening agent 1,3-bis(vinylsulfone)methane accounts for 0.2% of the total amount, and the rest is pure water.

[0097] The coating liquid composition of the anti-scratch matte layer Ⅰ1 is, by weight percentage, gelatin accounting for 5.4% of the total amount, the roughening agent is silicon dioxide with an average particle size of 4.3um accounting for 0.52% of the total amount, the preservative isothiazolinone accounting for 0.006% of the total amount, the film hardening agent 1,3-bis(vinylsulfone)methane accounting for 0.15% of the total amount, the pH adjuster potassium hydroxide accounting for 0.0046% of the total amount, the fluorosurfactant is FC-202 produced by Guangzhou Chunyan Industrial Co., Ltd., accounting for 0.078% of the total amount; the anionic surfactant sodium dodecylbenzenesulfonate accounting for 0.022% of the total amount, and the rest is pure water.

[0098] The coating liquid composition of the bonding layer I3 is, by weight percentage, the binder being an aliphatic anionic modified waterborne polyurethane resin dispersion, Hankins PU198 produced by Motan Chemical Company, accounting for 11.8% of the total weight; the surfactant sodium dodecylbenzenesulfonate accounting for 0.98% of the total weight; the film-forming agent being a binary copolymer of vinylidene chloride and acrylate accounting for 4.3% of the total weight; and the rest being pure water.

[0099] The coating liquid for bonding the antistatic layer 5 is composed of, by weight percentage, a binder which is an aliphatic anionic modified aqueous polyurethane resin dispersion, Hankins PU198 produced by Motan Chemical Company, accounting for 13.2% of the total weight; a surfactant, sodium dodecylbenzenesulfonate, accounting for 1.3% of the total weight; a film-forming agent, a binary copolymer of vinylidene chloride and acrylate, accounting for 3.8% of the total weight; an antistatic agent, ethoxylated lauryl amide, accounting for 3.5% of the total weight; and the remainder being pure water.

[0100] The coating liquid composition of the anti-halation layer 6 is, by weight percentage, 4.0% of gelatin, 0.003% of the total amount of the preservative phenol, 0.0025% of the total amount of the pH regulator citric acid, 0.01% of the total amount of the non-ionic surfactant polyoxyethylene ether, 0.04% of the total amount of the anionic surfactant sodium succinate sulfonate, 0.25% of the total amount of the anti-halation dye pentamethicone cyanine, 0.02% of the total amount of the thickener sodium polystyrene sulfonate, 1.8% of the total amount of the small molecule resin vinyl acetate and acrylate copolymer, Nipol LX552 latex produced by Japan Zeon Co., Ltd., and the rest is pure water.

[0101] The coating liquid composition of the anti-scratch matte layer II7 is, by weight percentage, 5.2% of the total amount of gelatin, 0.5% of the total amount of silica with an average particle size of 4.7um as a roughening agent, 0.003% of the total amount of phenol as a preservative, 0.12% of the total amount of 1,3-bis(vinylsulfone)methane as a hardening agent, 0.002% of the total amount of potassium hydroxide as a pH adjuster, 0.015% of the total amount of polyoxyethylene ether as a nonionic surfactant, 0.07% of the total amount of sodium succinate sulfonate as an anionic surfactant, and the rest is pure water.

[0102] Polyester support 4 uses the biaxially oriented polyester film transparent optical PET film that Yizheng Chemical Fiber Company produces in this example, 175 microns of thickness. Adhesive layer I 3 and the film-forming agent of bonding antistatic layer 5 use the 1# latex that Meng Li Chemical Industry Co., Ltd. produces. The baking temperature of adhesive layer I 3 and bonding antistatic layer 5 is between 100-120 ℃, and the baking temperature of all the other layers is between 30 ℃-50 ℃, uses hot air drying. Dried thickness is respectively: the thickness of bonding antistatic layer 5 is that the thickness of 0.653 micron, antihalation layer 6 is that the thickness of 2.236 microns, anti-scratch frosted layer II 7 is 1.128 microns, the thickness of adhesive layer I 3 is that the thickness of 0.671 micron, absorbing layer 12 is that the thickness of 0.752 micron, transparent interlayer 11 is that the thickness of 0.414 micron, photosensitive layer 2 is that the thickness of 2.386 microns, anti-scratch frosted layer I 1 is 1.523 microns.

[0103] Specific example 2:

[0104] The coating liquid composition of the anti-scratch matte layer Ⅰ1 is, by weight percentage, gelatin accounting for 7.4% of the total amount, silicon dioxide with an average particle size of 2.8um as a roughening agent accounting for 0.93% of the total amount, preservative isothiazolinone accounting for 0.0022% of the total amount, film hardening agent 1,3-bis(vinylsulfone)methane accounting for 0.084% of the total amount, pH regulator potassium hydroxide accounting for 0.0046% of the total amount, fluorosurfactant FC-202 produced by Guangzhou Chunyan Industrial Co., Ltd., accounting for 0.029% of the total amount; anionic surfactant sodium dodecylbenzenesulfonate accounting for 0.087% of the total amount, and the rest is pure water.

[0105] The coating liquid composition of the photosensitive layer 2 is as follows: gelatin accounts for 4.8% of the total amount, unexposed nano-scale silver halide particles are composed of a mixture of silver chloride and silver bromide at a molar ratio of 4.1:1, accounting for 7.6% of the total amount, citric acid as a pH adjuster accounts for 0.0074% of the total amount, sodium polystyrene sulfonate as a thickener accounts for 0.014% of the total amount, the small molecule resin vinyl acetate and acrylate copolymer is Nipol LX552 latex produced by Japan Zeon Co., Ltd., accounting for 4.3% of the total amount, benzotriazole as an anti-fogging agent accounts for 0.007% of the total amount, gold trichloride as a sensitizer accounts for 0.00029% of the total amount, ammonium thiocyanate as a sensitizer accounts for 0.00029% of the total amount, 1,3-bis(vinylsulfone)methane as a film hardener accounts for 0.41% of the total amount, and the rest is pure water.

[0106] The composition of the transparent interlayer coating liquid is as follows: gelatin accounts for 3.5% of the total weight percentage; the non-ionic surfactant is a fluorosurfactant, FC-202 produced by Guangzhou Chunyan Industrial Co., Ltd., with a usage of 0.035%; the anionic surfactant sodium dodecylbenzene sulfonate is 0.074%; the pH regulator citric acid is 0.041%; the thickener sodium polystyrene sulfonate is 0.021%; the preservative isothiazolinone is 0.0074%; and the rest is pure water.

[0107] The composition of the absorption layer coating liquid, by weight percentage, is 0.089% of water-soluble pentamethicone cyanine dye, 1.4% of gelatin, the non-ionic surfactant is a fluorosurfactant, FC-202 produced by Guangzhou Chunyan Industrial Co., Ltd., with a usage of 0.075%; the anionic surfactant sodium dodecylbenzenesulfonate is 0.068%, the penetrant sodium alkyl succinate sulfonate is 1.7%, the thickener sodium polystyrene sulfonate is 0.041%, the preservative isothiazolinone is 0.0039%, and the rest is pure water.

[0108] The coating liquid composition of the bonding layer I3 is, by weight percentage, the binder being an aliphatic anionic modified waterborne polyurethane resin dispersion, Hankins PU198 produced by Motan Chemical Company, accounting for 11.8% of the total weight; the surfactant sodium dodecylbenzenesulfonate accounting for 0.98% of the total weight; the film-forming agent being a binary copolymer of vinylidene chloride and acrylate accounting for 4.3% of the total weight; and the rest being pure water.

[0109] The coating liquid for bonding the antistatic layer 5 is composed of, by weight percentage, a binder which is an aliphatic anionic modified aqueous polyurethane resin dispersion, Hankins PU198 produced by Motan Chemical Company, accounting for 7.8% of the total weight; a surfactant, sodium dodecylbenzenesulfonate, accounting for 0.82% of the total weight; a film-forming agent, a binary copolymer of vinylidene chloride and acrylate, accounting for 2.9% of the total weight; an antistatic agent, ethoxylated lauramide, accounting for 1.8% of the total weight; and the remainder being pure water.

[0110] The coating liquid composition of the anti-halation layer 6 is, by weight percentage, 5.9% of gelatin, 0.0079% of the preservative phenol, 0.0064% of the pH adjuster citric acid, 0.04% of the non-ionic surfactant polyoxyethylene ether, 0.072% of the anionic surfactant sodium succinate sulfonate, 0.19% of the anti-halation dye pentamethicone cyanine, 0.047% of the thickener sodium polystyrene sulfonate, 3.1% of the small molecule resin vinyl acetate and acrylate copolymer, and the rest is pure water.

[0111] The coating liquid composition of the anti-scratch matte layer II7 is, by weight percentage, gelatin accounting for 6.8% of the total amount, PMMA with an average particle size of 2.5um as a roughening agent accounting for 0.24% of the total amount, preservative phenol accounting for 0.003% of the total amount, hardening agent 1,3-bis(vinylsulfone)methane accounting for 0.12% of the total amount, pH regulator potassium hydroxide accounting for 0.0076% of the total amount, non-ionic surfactant polyoxyethylene ether accounting for 0.012% of the total amount, anionic surfactant sodium succinate sulfonate accounting for 0.088% of the total amount, and the rest is pure water.

[0112] Polyester support 4 uses the biaxially oriented polyester film that Yizheng Chemical Fiber Company produces in this example, 175 microns of thickness. Adhesive layer I 3 and the film-forming agent of bonding antistatic layer 5 use the 1# latex that Meng Li Chemical Industry Co., Ltd. produces. Adhesive layer I 3 and the baking temperature of bonding antistatic layer 5 are between 100-120 ℃, and the baking temperature of all the other layers is between 30 ℃-50 ℃, uses hot air drying.Dried thickness is respectively: the thickness of bonding antistatic layer 5 is that the thickness of 0.784 micron, antihalation layer 6 is that the thickness of 3.357 microns, anti-scratch frosted layer II 7 is 1.524 microns, the thickness of adhesive layer I 3 is that the thickness of 0.669 micron, absorbing layer 12 is that the thickness of 0.822 micron, transparent interlayer 11 is that the thickness of 0.348 micron, photosensitive layer 2 is that the thickness of 2.698 microns, anti-scratch frosted layer I 1 is 1.215 microns.

[0113] Comparative Example 1 used a PCB photolithography film produced by Lucky Huaguang Printing Technology Co., Ltd., model RP-7.

[0114] Compared with comparative example 1, examples 1 and 2 of the present application contain an absorbent layer 12, and the composition and thickness of other layers and the drying conditions of each layer are the same.

[0115] The photo-painted circuit board films prepared in Examples 1 and 2 and the photo-painted circuit board film of Comparative Example 1 were tested under the same conditions, and the test performance was as follows:

[0116]

[0117] There's no direct way to measure the permeability of a transparent interlayer. Instead, we assess its permeability by measuring the minimum blackness (technically known as "fog") formed after developing and fixing the photo-painted circuit board film without exposure. Normally, the fog level should be ≤0.04. If the transparent interlayer's permeability is poor, the fog level will be >0.04 after developing and fixing the photo-painted circuit board film without exposure. The transparent interlayer's permeability ensures that the fog level remains ≤0.04 after developing and fixing the photo-painted circuit board film without exposure. The transparent interlayer, as described in the present invention, does not contain substances that affect light transmittance and therefore has no effect on light transmittance. The degree of diffusion of the water-soluble anti-halation dye within the absorbing layer 12 is determined by the maximum blackness (technically known as the maximum density) of the photo-drawing circuit board film after exposure, development, and fixing. A normal photo-drawing circuit board film has a maximum density of 4.5 or higher after exposure, development, and fixing. If the water-soluble anti-halation dye diffuses upward through the transparent interlayer into the photosensitive layer, it will affect the maximum density after exposure, development, and fixing. The greater the diffusion, the lower the maximum density. The interlayer of the present invention effectively blocks the diffusion of the water-soluble anti-halation dye from the absorbing layer into the photosensitive layer, maintaining a maximum density of 4.5 or higher.

[0118] The transparent interlayer in Example 1 of the present invention has good effects on the permeability and the ability of the transparent interlayer to block the diffusion of water-soluble dyes into the photosensitive layer.

[0119] The lines (1 mil) of the photo-painted circuit board film of Comparative Example 1 after photo-painting, developing, fixing and washing are as follows: Figure 4 As shown;

[0120] The line width and line spacing of the photo-painted line are 1 mil, and the line width and line spacing should both be 1 mil. However, as can be seen from this picture, the line width of the photo-painted circuit board film in Example 1 after processing and washing is significantly larger than the line spacing, and there are many burrs on the edges of the lines. The high-end circuit boards produced are very likely to short-circuit, resulting in waste, and cannot meet the requirements of high-end photo-painted circuit board production.

[0121] The lines (1 mil) of the photo-painted circuit board film prepared in Example 1 after photo-painting, developing, fixing and washing are as follows: Figure 5 As shown; the lines (1 mil) of the photo-painted circuit board film prepared in Example 2 after photo-painting, developing, fixing and washing are as shown Figure 6 shown.

[0122] With the development of electronic technology, the integration of electronic components is becoming increasingly higher and their size is becoming smaller and smaller. Reducing the line width and line spacing of circuits to fully utilize the limited area is an inevitable requirement for the manufacturing of electronic components. However, as the line width becomes finer, the laser light produces diffuse reflection at the PET interface, causing secondary exposure of the photosensitive layer. This causes the lines to become wider, the line spacing to become narrower, and the line edges to become more burred. This can easily cause two circuits that should be insulated to short circuit due to the reduced line spacing, causing the circuit board to be scrapped and resulting in huge losses for PCB manufacturers.

[0123] After processing, the light-drawn circuit board films prepared using Examples 1 and 2 of the present invention have substantially the same line width and line spacing of 1 mil lines, with no significant difference. The line edges are smoother than those of the light-drawn circuit board film of Comparative Example 1, meeting the manufacturing requirements for fine lines on high-end circuit boards.

[0124] Description: This application absorbs the diffusely reflected light generated at the PET interface by adding an absorption layer and a transparent interlayer, prevents the photosensitive layer from being exposed to secondary exposure, reduces the difference between the line width and line spacing of the light-drawn lines and the lines of the original circuit diagram, improves the smoothness of the line edges, and achieves the purpose of improving the line resolution of the light-drawn circuit board film.

[0125] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. It should be pointed out that for those skilled in the art and any technician familiar with this technical field, without departing from the overall concept of the present invention, the technical solution and the inventive concept of the present invention are equivalently replaced or changed, and several changes and improvements are made, which should also be regarded as the scope of protection of the present invention.

Claims

1. A photo-painted circuit board film comprising a PET substrate, the back side of which is provided with, from near to far, an adhesive antistatic layer, an anti-halation layer, and an anti-scratch frosted layer II, characterized in that: The front of the PET substrate is provided with an adhesive layer, an absorption layer, a transparent interlayer, a photosensitive layer, and an anti-scratch frosted layer I in order from near to far; The transparent interlayer coating liquid applied and dried to form the transparent interlayer comprises, by weight percentage, 2%-4% gelatin, 0.01%-0.1% nonionic surfactant, 0.01%-0.1% anionic surfactant, 0.01%-0.1% pH adjuster, 0.02%-0.1% thickener, 0.001%-0.01% preservative, and the remainder pure water; The absorption layer coating liquid is coated and dried to form an absorption layer, and the amount of the water-soluble anti-halation dye accounts for 0.04%-0.1% of the total weight percentage.

2. The photo-painted circuit board film according to claim 1, characterized in that: The thickness of the transparent interlayer is 0.2um-0.8um.

3. The photo-painted circuit board film according to claim 1, characterized in that: In the transparent interlayer coating liquid: the nonionic surfactant is a fluorine surfactant, polyoxyethylene ether, fatty acid polyoxyethylene ester or polyol, and the anionic surfactant is a fatty acid salt or sulfonate; the pH adjuster is at least one of a weak acid, a weak base, a low concentration of a strong acid or a low concentration of a strong base; the thickener is one of sodium polyacrylate, sodium polystyrene sulfonate, polyvinyl pyrrolidone or sodium carboxymethyl cellulose; and the preservative is one of sodium benzoate, phenol, potassium sorbate, butyl parahydroxybenzoate or isothiazolinone.

4. The photo-painted circuit board film according to claim 1, characterized in that: The thickness of the absorption layer is 0.5um-2um.

5. The photo-painted circuit board film according to claim 1, characterized in that: The absorbing layer coating liquid which is coated and dried to form the absorbing layer comprises, by weight percentage, 0.04%-0.1% of a water-soluble anti-halation dye, 1%-2% of gelatin, 0.01%-0.1% of a nonionic surfactant, 0.01%-0.1% of anionic surfactant, 0.5%-2% of a penetrant, 0.02%-0.1% of a thickener, 0.001%-0.01% of a preservative, and the remainder being pure water.

6. The photo-painted circuit board film according to claim 5, characterized in that: In the absorption layer coating liquid: the nonionic surfactant is a fluorosurfactant, polyoxyethylene ether, fatty acid polyoxyethylene ester or polyol, the anionic surfactant is a fatty acid salt or sulfonate; the penetrant is fatty alcohol polyoxyethylene ether, sodium alkylbenzene sulfonate or sodium alkylnaphthalene sulfonate; the thickener is sodium polyacrylate, sodium polystyrene sulfonate, polyvinyl pyrrolidone or sodium carboxymethyl cellulose; the preservative is phenol, sodium benzoate, potassium sorbate, butyl parahydroxybenzoate or isothiazolinone; the water-soluble anti-halation dye is pentamethicone cyanine dye.

7. The photo-painted circuit board film according to claim 1, characterized in that: The thickness of the anti-halation layer is 2-4um.

8. The photo-painted circuit board film according to claim 1, characterized in that: The anti-halation layer coating liquid that is coated and dried to form an anti-halation layer comprises, by weight percentage, 3%-7% of gelatin, 0.001%-0.01% of preservatives, 0.001%-0.01% of pH adjusters, 0.01%-0.1% of nonionic surfactants, 0.01%-0.1% of anionic surfactants, 0.1%-0.1% of water-soluble anti-halation dyes, 0.01%-0.1% of thickeners, 1%-5% of small molecule resins, and the remainder being pure water.

9. The photo-painted circuit board film according to claim 8, characterized in that: In the anti-halation layer coating liquid: the preservative is sodium benzoate, phenol, potassium sorbate, butyl parahydroxybenzoate or isothiazolinone; the pH adjuster is a weak acid, a weak base or a low concentration of sodium hydroxide or potassium hydroxide; the non-ionic surfactant is a fluorosurfactant, polyoxyethylene ether, fatty acid polyoxyethylene ester or a polyol; the anionic surfactant is a fatty acid salt or sulfonate; the thickener is sodium polyacrylate, sodium polystyrene sulfonate, polyvinyl pyrrolidone or sodium carboxymethyl cellulose; the water-soluble anti-halation dye is pentamethyl cyanine dye; the small molecule resin is a copolymer of vinyl acetate and acrylate, a copolymer of styrene and acrylate or a copolymer of vinylidene chloride and acrylate.

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