A high-performance circuit board solder mask printing process

Abstract

The application belongs to the technical field of circuit board printing, and particularly relates to a high-performance circuit board anti-soldering printing process. The high-performance circuit board anti-soldering printing process comprises the following steps: S1, pretreatment; S2, preparation of anti-soldering ink; S3, silk screen printing; and S4, curing. Through the pretreatment fine etching, preparation of anti-soldering ink, high-precision silk screen printing and segmented curing process, the adhesion, temperature resistance and thermal shock resistance of the anti-soldering layer are significantly improved, the dielectric loss and process defect rate are reduced, and the strict requirements of high-frequency and high-speed circuits on reliability and signal integrity are fully met.

Description

Technical Field

[0001] This invention belongs to the field of circuit board printing technology, and specifically relates to a high-performance circuit board solder resist printing process. Background Technology

[0002] With the rapid development of 5G communication, autonomous driving, and high-density integrated circuits, the solder resist layer of circuit boards faces multiple challenges, including high-frequency signal transmission, high-temperature soldering, and reliability in complex environments. Traditional solder resist printing processes often employ a single resin system combined with mechanical roughening, but these suffer from insufficient adhesion, high dielectric loss, and poor temperature resistance. Conventional micro-etching processes often use a sulfuric acid / hydrogen peroxide system, which can roughen the copper surface, but the rapid oxidation rate can lead to uneven surface roughness, and residual acid is difficult to completely remove, causing interface corrosion defects. Furthermore, existing solder resist ink systems mostly use epoxy resin or acrylic resin as a single substrate, making it difficult to balance high-temperature stability and low dielectric requirements. While epoxy resin systems offer excellent heat resistance, their dielectric constant (ε) is generally higher than 3.8, making it difficult to meet the signal integrity requirements of 5G communication; while acrylic systems have excellent dielectric properties, their temperature resistance is insufficient to 220℃, failing to pass lead-free reflow soldering certification.

[0003] In terms of filler applications, existing technologies mostly rely on single nano-silica to reduce the dielectric constant. However, its wide particle size distribution and tendency to agglomerate lead to increased defects at the filler-resin interface and high dielectric loss (Df). At the same time, traditional curing processes use single-stage high-temperature curing, resulting in uneven resin crosslinking density, internal stress accumulation, microcracks or interlayer separation, poor thermal shock resistance, and seriously affecting long-term reliability.

[0004] Therefore, a systematic solution is urgently needed to achieve a comprehensive improvement in the performance of the weld shield through collaborative innovation in materials, processes, and structures. Summary of the Invention

[0005] The purpose of this invention is to provide a high-performance circuit board solder resist printing process. Through pretreatment fine micro-etching, preparation of solder resist ink, high-precision screen printing, and segmented curing process, the adhesion, temperature resistance and thermal shock resistance of the solder resist layer are significantly improved, while reducing dielectric loss and process defect rate.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The high-performance circuit board solder resist printing process includes the following steps:

[0008] S1, Preprocessing;

[0009] S2. Prepare solder resist ink;

[0010] S3, screen printing;

[0011] S4, Curing.

[0012] The specific steps of step S1 are as follows: after removing the oil stains on the surface of the circuit board, the surface of the circuit board is micro-etched using a micro-etching agent to obtain a micro-etched circuit board.

[0013] Preferably, the main components of the micro-etching agent are: 75-85 g / L sodium persulfate, 35-45 g / L nitric acid, 5-10 g / L tetramethylammonium chloride, and 0.5-1.0 g / L benzotriazole, and the solvent is deionized water.

[0014] The preparation steps of the micro-etching agent are as follows: Sodium persulfate and tetramethylammonium chloride are added to deionized water, stirred evenly, and the temperature is controlled at room temperature. Nitric acid is slowly added, stirred evenly, and then benzotriazole is added and stirred evenly to obtain the micro-etching agent.

[0015] The specific conditions for the micro-etching treatment are as follows: the micro-etching temperature is 28-32℃ for the first 20 seconds, then the temperature is reduced to 23-25℃ until the copper surface roughness Ra is 0.35-0.45μm. After removal, the residual acid is neutralized with a buffer solution of pH=6.5-7.5, and then thoroughly rinsed with ultrapure water. After immersion in a silane coupling agent solution, the reaction is carried out at 38-42℃ for 4-6 minutes, and then the surface is baked at 78-82℃ for 8-12 minutes.

[0016] Preferably, in the silane coupling agent solution, the mass fraction of the silane coupling agent is 1%-3%, and the solvent is an aqueous ethanol solution with a mass fraction of 65%-75%.

[0017] Preferably, the silane coupling agent comprises 3-aminopropyltriethoxysilane.

[0018] The combination of sodium persulfate, nitric acid, tetramethylammonium chloride, and benzotriazole significantly improves etching uniformity and adhesion. This is likely because sodium persulfate, acting as an oxidant, preferentially etches the copper grain boundaries, forming nanoscale pits; nitric acid dissolves oxidation products to prevent passivation layer formation, while simultaneously complexing with tetramethylammonium chloride to copper ions, avoiding localized over-etching; and benzotriazole adsorbs onto low-lying areas of the copper surface, inhibiting lateral corrosion. Through the synergistic effect of these four chemicals, a dynamic balance is achieved in the three steps of oxidation, dissolution, and complexation, allowing for precise control of the copper surface roughness (Ra) within the range of 0.35-0.45 μm. This increases the mechanical interlocking area, and combined with the treatment of silane coupling agents, significantly improves adhesion. Simultaneously, uniform etching reduces stress concentration, lowers the circuit breakage rate, and reduces the defect rate.

[0019] Preferably, the solder resist ink, by weight, comprises 65-75 parts of resin matrix, 5-10 parts of curing agent, 12-20 parts of modified filler, and 0.5-1.5 parts of additives.

[0020] Preferably, the resin matrix includes epoxy acrylate, phenolic epoxy resin, and polyimide prepolymer.

[0021] Preferably, the mass ratio of the epoxy acrylate, phenolic epoxy resin, and polyimide prepolymer is (7-9):(4-6):1; more preferably, it is 8:5:1.

[0022] Through a three-component hybrid design of epoxy acrylate, phenolic epoxy resin, and polyimide prepolymer, adhesion, temperature resistance, and thermal shock resistance are simultaneously improved, while the dielectric constant is reduced. This is likely because the hydroxyl groups in bisphenol A epoxy acrylate form hydrogen bonds with the copper surface, providing initial adhesion; the polyphenylene ring structure of bisphenol F phenolic epoxy resin forms a dense cross-linked network, inhibiting high-temperature deformation; and the rigid segments of the polyimide prepolymer are interwoven within the epoxy network, blocking molecular chain slippage at high temperatures, while simultaneously reducing the dielectric constant, decreasing signal loss, and improving the transmission speed of high-frequency circuits. The epoxy resin provides interfacial bonding, the phenolic epoxy forms the framework, and the polyimide enhances the upper temperature limit; the three work synergistically to form a "rigid-flexible" composite structure, thereby improving temperature resistance and impact resistance, while also enhancing dielectric properties. The rigid-flexible structure adapts to the thermal expansion and contraction of the copper surface, improving adhesion retention.

[0023] Preferably, the epoxy acrylate is a bisphenol A type epoxy resin with a functionality of 2-3, a viscosity of 9000-18000 cps at 30°C, and an acid value ≤2.5 mgKOH / g.

[0024] In some preferred embodiments, the epoxy acrylate is derived from Boxin, B-123.

[0025] Preferably, the phenolic epoxy resin has an epoxy equivalent of 160-180 g / eq and a viscosity of 2000-5000 cps at 25°C.

[0026] In some preferred embodiments, the phenolic epoxy resin is sourced from South Asia, NPEF-170.

[0027] The method for preparing the polyimide prepolymer includes the following steps: under nitrogen protection, 4,4'-diaminodiphenyl ether is dissolved in N-methylpyrrolidone and stirred until completely dissolved. Then, pyromellitic dianhydride is added in batches, the reaction temperature is controlled at ≤40℃, and the mixture is stirred at 300-500 rpm for 24 hours. Benzoic anhydride is added to obtain a polyamic acid solution, which is then vacuum dehydrated at 80℃ to an intrinsic viscosity of 0.4-0.6 dL / g to obtain the polyimide prepolymer.

[0028] Preferably, the molar ratio of 4,4'-diaminodiphenyl ether to pyromellitic dianhydride is 1:1.

[0029] Preferably, the amount of N-methylpyrrolidone added is twice the total mass of 4,4'-diaminodiphenyl ether and pyromellitic dianhydride.

[0030] Preferably, the amount of benzoic anhydride added is 1% to 5% of the molar amount of pyromellitic dianhydride.

[0031] By precisely matching the physical properties of epoxy acrylate, phenolic epoxy resin, and polyimide prepolymer, process compatibility and performance are maximized. Epoxy acrylate with appropriate functionality ensures proper crosslinking, avoiding the brittleness and thermal shock resistance caused by high functionality; phenolic resin with a specific epoxy equivalent extends the workable time and reacts proportionally with dicyandiamide curing agent to ensure complete crosslinking, while its low viscosity ensures filler dispersibility; the polyimide prepolymer is compatible with the epoxy resin, preventing interfacial defects caused by phase separation and adjusting the system's thixotropy. Low-viscosity epoxy acrylate ensures filler dispersibility, the high epoxy equivalent of phenolic epoxy improves crosslinking efficiency, and the viscosity matching of the polyimide prepolymer prevents sedimentation. The matching rheological properties of the three components reduce phase separation, lower the defect rate, improve thermal shock resistance, and also form a homogeneous dielectric network.

[0032] Preferably, the curing agent includes dicyandiamide and 2-ethyl-4-methylimidazole.

[0033] Preferably, the mass ratio of dicyandiamide to 2-ethyl-4-methylimidazole is (13-15):1; more preferably, it is 14:1.

[0034] The preparation method of the modified filler includes the following steps: immersing the filler in a silane coupling agent solution, treating it at 58-62℃ for 2-3 hours, removing it, rinsing it 2-3 times with deionized water, and then vacuum drying it to obtain the filler.

[0035] Preferably, the filler comprises one or more of nano-silica, boron nitride, aluminum oxide, graphene, and silver nanowires.

[0036] Preferably, the mass ratio of the nano-silica, boron nitride, and aluminum oxide is (10-14):(2-4):1; more preferably, it is 12:3:1.

[0037] By complementing the functions of various filler morphologies, a synergistic improvement in dielectric performance and reliability is achieved. This is likely because nano-silica can fill the free volume of the resin, reducing polarizability; the two-dimensional thermal conductivity path of plate-like boron nitride disperses heat and inhibits local heat accumulation; and the hard alumina particles enhance wear resistance and prevent crack propagation. Silica reduces dielectric loss, boron nitride improves heat dissipation, and alumina enhances mechanical durability. The three work synergistically to form a three-in-one functional network of "dielectric-thermal-wear resistance," thereby optimizing dielectric performance and thermal shock resistance.

[0038] Preferably, the nano-silica is spherical with an average particle size of 15-25 nm and a specific surface area of ​​145-160 m². 2 / g.

[0039] Preferably, the boron nitride has a sheet diameter of 1-5 μm, a thickness of <5 nm, an aspect ratio >50, and a bulk density of 0.1-0.3 g / cm³. 3 .

[0040] Preferably, the alumina is a mixed phase of α and γ with a particle size of 25-35 nm.

[0041] In some preferred embodiments, the nano-silica, boron nitride, and alumina are all sourced from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0042] By designing a gradient of the physical parameters of the filler, the beneficial effects of the filler were further optimized. This may be because by controlling the particle size and specific surface area of ​​silica, small sizes can fill micropores, and a specific specific surface area is suitable for silane coupling agent coating; the large aspect ratio of boron nitride flakes can form a continuous thermally conductive network, and a specific packing density ensures dispersion stability; the use of a mixture of α-phase and γ-phase alumina provides high-temperature stability, while the γ-phase improves dispersibility, reduces ink viscosity, and balances the various properties of solder resist ink. At the same time, the α-phase can inhibit the high-temperature shrinkage of the γ-phase, improve temperature resistance, and the particle size is gradient with that of silica, reducing filler sedimentation and agglomeration, forming a dense stacked structure, thereby making the film thickness uniform and reducing the defect rate.

[0043] Preferably, the additives include leveling agents and defoamers.

[0044] Preferably, the leveling agent is a polyether-modified siloxane leveling agent with a viscosity of 500-700 mPa·s at 25°C.

[0045] In some preferred embodiments, the leveling agent is sourced from Shanghai Ziyi Chemical Co., Ltd., ZY-1333.

[0046] Preferably, the defoamer is a silicone polyether defoamer, nonionic, with a solid content of 29%-31% and a viscosity of 1000-4000 mPa·s at 25°C.

[0047] In some preferred embodiments, the defoamer is sourced from Shanghai Ziyi Chemical Co., Ltd., ZY-2169.

[0048] Preferably, the mass ratio of the leveling agent to the defoamer is (1.5-2.5):1.

[0049] The preparation method of the solder resist ink includes the following steps: mixing resin matrix and modified filler, performing shear dispersion and ultrasonic dispersion in sequence, adding curing agent and additives, stirring at 80-100 rpm for 1-5 min, vacuum degassing until the bubble residual rate is <0.1%, and passing through a 300-mesh sieve to obtain the ink.

[0050] Preferably, the specific conditions for shear dispersion are: rotation speed of 2000-3000 rpm and time of 10-20 min.

[0051] Preferably, the specific conditions for ultrasonic dispersion are: frequency of 25-30kHz, power of 200-300W, and time of 5-15min.

[0052] The specific steps of step S3 are as follows: fix the micro-etched circuit board on the printing table, align it with the screen markings, pre-coat it with solder resist ink, and then accurately fill it to obtain a wet film.

[0053] Preferably, the wire mesh is a nickel mesh with a mesh count of 400, a wire diameter of 23-27 μm, and a tension of 21-23 N / cm.

[0054] Preferably, the specific conditions for the pre-coating are: doctor blade pressure of 2-4 kg / cm and speed of 190-210 mm / s.

[0055] Preferably, the specific conditions for precise filling are: scraper pressure of 4-6 kg / cm and speed of 140-160 mm / s.

[0056] Preferably, the thickness of the wet film is: 16-20 μm for the circuit area and 27-33 μm for the solder resist area.

[0057] The specific steps of step S4 are as follows: first perform photocuring, then perform thermal curing, and finally perform infrared annealing.

[0058] Preferably, the specific conditions for photocuring are: ultraviolet curing, with a light intensity of 180-220 mW / cm². 2 The illumination time is 28-32 seconds.

[0059] Preferably, the thermosetting is a multi-stage gradient temperature curing process, with the first stage temperature at 78-82℃ and a curing time of 12-18 min; the second stage temperature at 118-122℃ and a curing time of 38-42 min; and the third stage temperature at 178-182℃ and a curing time of 28-32 min.

[0060] Preferably, the specific conditions for infrared annealing are: mid-wave infrared, temperature of 58-62℃, and time of 8-12 minutes.

[0061] By employing a three-stage curing process—photocuring, thermocuring, and infrared annealing—and coupling energy fields, the contradiction between curing efficiency and interfacial stress is resolved, thereby improving temperature resistance, thermal shock resistance, and dielectric properties while reducing the defect rate. This is likely because UV pre-curing first rapidly gels the surface, locking in filler distribution and preventing dielectric inhomogeneity caused by sedimentation; then, gradient thermocuring involves a first stage where gentle heating allows for slow solvent evaporation, preventing sudden boiling and microbubble formation; a second stage where the dicyandiamide decomposition temperature is matched to trigger the main crosslinking reaction; and a third stage promoting polyimide imidization to form a high-temperature resistant, dense network. The gradient heating allows the crosslinking reaction to proceed step by step, avoiding interfacial delamination caused by drastic temperature changes, thus improving temperature resistance and thermal shock tolerance; finally, infrared annealing uses mid-wave infrared targeting to eliminate residual stress at the resin-copper interface. Photocuring preserves shape, thermocuring densifies, and infrared annealing relieves stress, with energy input distributed in a gradient from surface to bulk to overall structure, thereby reducing the defect rate and improving temperature resistance and thermal shock resistance.

[0062] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0063] 1. This invention provides a high-performance circuit board solder resist printing process. Through pretreatment fine micro-etching, preparation of solder resist ink, high-precision screen printing, and segmented curing process, the adhesion, temperature resistance and thermal shock resistance of the solder resist layer are significantly improved, while dielectric loss and process defect rate are reduced, fully meeting the stringent requirements of high-frequency and high-speed circuits for reliability and signal integrity.

[0064] 2. The present invention significantly improves etching uniformity and adhesion by combining sodium persulfate, nitric acid, tetramethylammonium chloride and benzotriazole.

[0065] 3. This invention utilizes a three-component hybrid design of epoxy acrylate, phenolic epoxy resin, and polyimide prepolymer to simultaneously improve adhesion, temperature resistance, and thermal shock resistance, while reducing the dielectric constant. By precisely matching the physical properties of the three components—epoxy acrylate, phenolic epoxy resin, and polyimide prepolymer—process adaptability and performance are maximized.

[0066] 4. This invention achieves a synergistic improvement in dielectric performance and reliability through the complementary functions of various filler types; and further optimizes the beneficial effects of the fillers through the gradient design of the physical parameters of each filler.

[0067] 5. This invention achieves curing in three stages—photocuring, thermal curing, and infrared annealing—through energy field coupling, thereby resolving the contradiction between curing efficiency and interfacial stress, thus improving temperature resistance, thermal shock resistance, and dielectric properties, while reducing the defect rate. Detailed Implementation

[0068] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0069] All raw materials used in this invention are commercially available, specifically:

[0070] Epoxy acrylate is a bisphenol A type epoxy resin with a functionality of 2-3, a viscosity of 9000-18000 cps at 30℃, and an acid value ≤2.5mgKOH / g. It comes from Boxin, B-123.

[0071] Phenolic epoxy resin, epoxy equivalent of 160-180 g / eq, viscosity of 2000-5000 cps at 25℃, from South Asia, NPEF-170.

[0072] Nano-silica is spherical with an average particle size of 15-25 nm and a specific surface area of ​​145-160 m². 2 / g; Boron nitride flakes have a diameter of 1-5μm, a thickness of <5nm, an aspect ratio >50, and a bulk density of 0.1-0.3g / cm³. 3 The alumina is a mixed α and γ phase with a particle size of 25-35 nm; all are from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0073] The leveling agent is a polyether-modified siloxane leveling agent with a viscosity of 500-700 mPa·s at 25℃. It is from Shanghai Ziyi Chemical Co., Ltd., and is designated as ZY-1333.

[0074] The defoamer is a silicone polyether defoamer, nonionic, with a solid content of 29%-31% and a viscosity of 1000-4000 mPa·s at 25℃. It is from Shanghai Ziyi Chemical Co., Ltd., and is designated as ZY-2169.

[0075] Example 1

[0076] This embodiment provides a high-performance circuit board solder resist printing process, the steps of which are as follows:

[0077] S1. After removing oil stains from the surface of the circuit board, a micro-etching agent is used to perform micro-etching treatment on the surface of the circuit board to obtain a micro-etched circuit board.

[0078] S2. Prepare solder resist ink;

[0079] S3, Screen Printing: Fix the micro-etched circuit board on the printing table, align it with the screen markings, pre-coat it with solder resist ink, and then precisely fill it to obtain a wet film;

[0080] S4, Curing.

[0081] The micro-etching agent consists of: 80 g / L sodium persulfate, 40 g / L nitric acid, 8 g / L tetramethylammonium chloride, 0.8 g / L benzotriazole, with the remainder being deionized water.

[0082] The preparation steps of the micro-etching agent are as follows: Sodium persulfate and tetramethylammonium chloride are added to deionized water, stirred evenly, and the temperature is controlled at room temperature. Nitric acid is slowly added, stirred evenly, and then benzotriazole is added and stirred evenly to obtain the micro-etching agent.

[0083] The specific conditions for the micro-etching treatment are as follows: the micro-etching temperature is 30℃ for the first 20 seconds, then the temperature is reduced to 25℃ until the copper surface roughness Ra is 0.4μm. After removal, the residual acid is neutralized with a buffer solution of pH=7.0, and then thoroughly rinsed with ultrapure water. After immersion in a silane coupling agent solution, the mixture is reacted at 40℃ for 5 minutes and then removed. Finally, it is baked at 80℃ for 10 minutes.

[0084] The silane coupling agent solution contains 2% silane coupling agent by mass and 70% ethanol aqueous solution by mass as solvent.

[0085] The silane coupling agent is 3-aminopropyltriethoxysilane.

[0086] The solder resist ink, by weight, is prepared from 70 parts resin matrix, 8 parts curing agent, 16 parts modified filler, and 1 part additive.

[0087] The resin matrix is ​​composed of epoxy acrylate, phenolic epoxy resin, and polyimide prepolymer in a mass ratio of 8:5:1.

[0088] The preparation method of the polyimide prepolymer includes the following steps: under nitrogen protection, 4,4'-diaminodiphenyl ether is dissolved in N-methylpyrrolidone and stirred until completely dissolved. Then, pyromellitic dianhydride is added in batches, the reaction temperature is controlled at ≤40℃, and the mixture is stirred at 400 rpm for 24 h. Benzoic anhydride is added to obtain a polyamic acid solution, which is then dehydrated under vacuum at 80℃ until the intrinsic viscosity is 0.5 dL / g to obtain the polyimide prepolymer.

[0089] The molar ratio of 4,4'-diaminodiphenyl ether to pyromellitic dianhydride is 1:1.

[0090] The amount of N-methylpyrrolidone added is twice the total mass of 4,4'-diaminodiphenyl ether and pyromellitic dianhydride.

[0091] The amount of benzoic anhydride added is 3% of the molar amount of pyromellitic dianhydride.

[0092] The curing agent is dicyandiamide and 2-ethyl-4-methylimidazole in a mass ratio of 14:1.

[0093] The modified filler is prepared by immersing it in a silane coupling agent solution, treating it at 60°C for 2.5 hours, rinsing it three times with deionized water, and then vacuum drying it to obtain the filler.

[0094] The filler is nano-silica, boron nitride, and aluminum oxide in a mass ratio of 12:3:1.

[0095] The additives are leveling agents and defoamers, with a mass ratio of 2:1.

[0096] The preparation method of the solder resist ink includes the following steps: mixing resin matrix and modified filler, performing shear dispersion and ultrasonic dispersion in sequence, adding curing agent and additives, stirring at 90 rpm for 3 min, vacuum degassing until the bubble residual rate is 0.05%, and passing through a 300-mesh sieve to obtain the ink.

[0097] The specific conditions for shear dispersion are: rotation speed of 2500 rpm and time of 15 min.

[0098] The specific conditions for ultrasonic dispersion are: frequency of 28kHz, power of 250W, and time of 10min.

[0099] The wire mesh is a nickel mesh with a mesh count of 400, a wire diameter of 25 μm, and a tension of 22 N / cm.

[0100] The specific conditions for the pre-coating are: doctor blade pressure of 3 kg / cm and speed of 200 mm / s.

[0101] The specific conditions for precise filling are: scraper pressure of 5 kg / cm and speed of 150 mm / s.

[0102] The thickness of the wet film is: 18 μm for the circuit area and 30 μm for the solder mask area.

[0103] The specific steps of step S4 are as follows: first perform photocuring, then perform thermal curing, and finally perform infrared annealing.

[0104] The specific conditions for photocuring are: ultraviolet curing, with a light intensity of 200 mW / cm². 2 The illumination time is 30 seconds.

[0105] The thermosetting process is a multi-stage gradient temperature curing process. The first stage temperature is 80℃ and the curing time is 15 min; the second stage temperature is 120℃ and the curing time is 40 min; and the third stage temperature is 180℃ and the curing time is 30 min.

[0106] The specific conditions for infrared annealing are: mid-wave infrared, temperature 60℃, time 10min.

[0107] Example 2

[0108] The difference between this embodiment and Embodiment 1 is that the resin matrix is ​​epoxy acrylate, phenolic epoxy resin, and polyimide prepolymer in a mass ratio of 9:6:1.

[0109] Comparative Example 1

[0110] The difference between this comparative example and Example 1 is that the composition of the micro-etching agent is: 80 g / L sodium persulfate, 40 g / L nitric acid, and the remaining solvent is deionized water.

[0111] Comparative Example 2

[0112] The difference between this comparative example and Example 1 is that the resin matrix is ​​epoxy acrylate.

[0113] Comparative Example 3

[0114] The difference between this comparative example and Example 1 is that the resin matrix includes polyester acrylate, phenolic epoxy resin, and polyimide prepolymer in a mass ratio of 8:5:1.

[0115] The polyester acrylate has a functionality of 4, a viscosity of 1600-2450 mPa·s at 60°C, and an acid value ≤9 mgKOH / g.

[0116] The polyester acrylate is from American company Ebecryl811.

[0117] The phenolic epoxy resin has an epoxy equivalent of 175-182 g / eq and a viscosity of 20,000-50,000 cps at 25°C.

[0118] The phenolic epoxy resin is from Chang Chun Corporation in Taiwan Province, EPN 1138.

[0119] Comparative Example 4

[0120] The difference between this comparative example and Example 1 is that the filler is nano-silica.

[0121] Comparative Example 5

[0122] The difference between this comparative example and Example 1 is that the nano-silica is spherical with an average particle size of 100nm and comes from Nanjing Dongna Biotechnology Co., Ltd.

[0123] The boron nitride flakes have a diameter of 1-3 μm and a thickness of <100 nm, and are sourced from Beijing Deco Island Gold Technology Co., Ltd., and are sheet-like nano boron nitride.

[0124] The alumina is a γ phase with a particle size of 10-15 nm and comes from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0125] Comparative Example 6

[0126] The difference between this comparative example and Example 1 is that the specific steps of step S4 are: thermosetting.

[0127] Comparative Example 7

[0128] The difference between this comparative example and Example 1 is that the thermosetting temperature is 180°C and the curing time is 60 min.

[0129] Performance testing

[0130] Adhesion was tested according to the method in ASTM D3359. Dielectric constant at 10 GHz was tested according to the method in GB / T 12636-1990. Temperature resistance was tested according to the method in IPC-TM-650, by immersing the sample in molten solder (Sn96.5 / Ag3.0 / Cu0.5) at (288±5)℃ for 10 seconds each time; repeated 5 times, with intervals between cooling to room temperature; microscopic examination for delamination and blistering, and X-ray examination for internal cracks. Thermal shock resistance: The sample was placed in a high and low temperature test chamber, with a 15-minute cycle of -55℃ for 10 minutes and 125℃ for 10 minutes, with a transition time ≤1 minute. After each 5 cycles, the edge of the solder resist was pried open with a blade to check for cracking. Defect rate: Ten 10mm × 10mm areas of the circuit board were randomly inspected using a 50x optical microscope. The number of voids (diameter > 0.1mm) and cracks (length > 0.5mm) was counted. The defect rate was calculated as (number of defect points / total inspected area) × 100%. The results are shown in Table 1.

[0131] Table 1 Measurement Results

[0132]

[0133]

[0134] According to statistics, the processes of Examples 1-2 of this invention significantly improve the adhesion, temperature resistance, and thermal shock resistance of the solder resist layer, while reducing dielectric loss and process defect rate. Comparative Example 1 did not add tetramethylammonium chloride and benzotriazole; Comparative Example 2's resin matrix consisted only of epoxy acrylate; Comparative Example 3 used polyester acrylate instead of epoxy acrylate, and the functionality and viscosity of the resin matrix were mismatched; Comparative Example 4 used only nano-silica as filler; Comparative Example 5's filler particle size and aspect ratio were mismatched; Comparative Example 6 only underwent thermosetting, and Comparative Example 7 only underwent single-stage thermosetting. All performance characteristics were inferior to Example 1. Therefore, the circuit board prepared using the method described in this application significantly improves the adhesion, temperature resistance, and thermal shock resistance of the solder resist layer, while reducing dielectric loss and process defect rate, fully meeting the stringent reliability and signal integrity requirements of high-frequency and high-speed circuits.

[0135] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-performance circuit board solder resist printing process, characterized in that, Includes the following steps: S1. Pretreatment: After removing oil stains from the surface of the circuit board, a micro-etching agent is used to perform micro-etching treatment on the surface of the circuit board to obtain a micro-etched circuit board. S2. Prepare solder resist ink; S3, screen printing; S4. Curing: First, perform light curing, then heat curing, and finally infrared annealing. The main components of the micro-etching agent are: 75-85 g / L sodium persulfate, 35-45 g / L nitric acid, 5-10 g / L tetramethylammonium chloride, and 0.5-1.0 g / L benzotriazole, with deionized water as the solvent; The solder resist ink, by weight, is prepared from raw materials including 65-75 parts resin matrix, 5-10 parts curing agent, 12-20 parts modified filler, and 0.5-1.5 parts additives. The resin matrix includes epoxy acrylate, phenolic epoxy resin, and polyimide prepolymer; The fillers include nano-silica, boron nitride, and aluminum oxide.

2. The high-performance circuit board solder resist printing process according to claim 1, characterized in that, The mass ratio of epoxy acrylate, phenolic epoxy resin, and polyimide prepolymer is (7-9):(4-6):

1.

3. The high-performance circuit board solder resist printing process according to claim 2, characterized in that, The epoxy acrylate is a bisphenol A type epoxy resin with a functionality of 2-3, a viscosity of 9000-18000 cps at 30℃, and an acid value ≤2.5mgKOH / g.

4. The high-performance circuit board solder resist printing process according to claim 3, characterized in that, The phenolic epoxy resin has an epoxy equivalent of 160-180 g / eq and a viscosity of 2000-5000 cps at 25°C.

5. The high-performance circuit board solder resist printing process according to claim 4, characterized in that, The filler is a modified filler, and the preparation method includes the following steps: immersing the filler in a silane coupling agent solution, treating it at 58-62℃ for 2-3 hours, taking it out, rinsing it with deionized water 2-3 times, and then vacuum drying it to obtain the filler.

6. The high-performance circuit board solder resist printing process according to claim 5, characterized in that, The nano-silica is spherical with an average particle size of 15-25 nm and a specific surface area of ​​145-160 m². 2 / g.

7. The high-performance circuit board solder resist printing process according to claim 6, characterized in that, The boron nitride has a sheet diameter of 1-5 μm, a thickness of <5 nm, an aspect ratio >50, and a bulk density of 0.1-0.3 g / cm³. 3 .

8. A product prepared by the high-performance circuit board solder resist printing process according to any one of claims 1 to 7.

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