An ink material for low warpage solder resist, and a preparation method and application thereof

Abstract

This invention discloses a low-warpage solder resist ink material, its preparation method, and its application, belonging to the field of ink material preparation technology. It addresses the technical problem that the anti-shrinkage and anti-warpage properties of existing ink materials need further improvement. Specifically, it comprises the following components by weight: 30-50 parts alkali-soluble modified resin, 15-20 parts shrinkage-modified filler, 2-5 parts photoinitiator, 0.5-3 parts pigment, 1-3 parts leveling agent, and 15-25 parts solvent. This invention involves preparing negative thermal expansion nano-zirconium tungstate, coating it with polydopamine, grafting photosensitive double bonds to obtain an anti-shrinkage filler, esterifying o-cresylaldehyde epoxy resin with acrylate, and then modifying it with a dibasic anhydride to obtain an internally plasticized resin. Finally, the components are premixed under yellow light and water-cooled three-roll milling to obtain a low-warpage solder resist ink, which not only improves the anti-shrinkage and anti-warpage properties of the ink material but also enhances its mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of ink material preparation technology, specifically to a low warpage solder resist ink material, its preparation method, and its application. Background Technology

[0002] As printed circuit boards (PCBs) move towards high-density interconnection, thinning, and larger sizes, solder resist inks, in addition to needing alkali-soluble development, optical imaging resolution, adhesion, and heat resistance, also require low warpage characteristics after curing, which has become a key indicator for evaluating system stability. Traditional solder resist layers inevitably experience volume shrinkage and thermal stress accumulation during exposure curing and subsequent heat treatment. This is especially true in thin boards, flexible substrates, or structures with locally high copper thickness, which can easily induce board warpage, edge stress concentration, and dimensional shifts in patterned areas, limiting the further application of solder resist inks in the field of high-reliability electronic packaging.

[0003] Currently, solder resist inks are typically improved by adding plasticizing components, adjusting the curing process, or optimizing baking conditions to enhance their anti-warping properties. Alternatively, fillers such as silica, calcium carbonate, and talc are used to reduce system shrinkage. Stress concentration is mitigated through processes such as segmented exposure and slow-heat baking. While these solutions can improve local deformation to some extent, they generally suffer from limited shrinkage suppression, difficulty in balancing developability and heat resistance, insufficient filler dispersion stability, and uneven stress transmission in multiphase systems.

[0004] To improve the anti-warping solder resist performance of ink materials, highly cross-linked photocurable resins are prone to large volume shrinkage during the dense network formation process. If the flexibility of the resin chain segments is not sufficiently adjusted, the internal stress is difficult to release in time. On the other hand, conventional inorganic fillers mostly only serve as inert fillers, and their thermal expansion behavior differs from that of the resin matrix. Moreover, their surface functionalization is limited, which can easily lead to insufficient interfacial wetting, uneven dispersion, and local fluctuations in cross-linking density. At the same time, during the grinding, dispersion, and storage process, the active components of the solder resist ink may undergo pre-reaction or micro-agglomeration, further amplifying the stress concentration and dimensional instability after curing.

[0005] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a low-warpage solder resist ink material, its preparation method, and its application, in order to solve the technical problem that the anti-shrinkage and anti-warpage properties of ink materials in the prior art need to be further improved.

[0007] The objective of this invention can be achieved through the following technical solution: a low warpage solder resist ink material, comprising the following components by weight: 30-50 parts alkali-soluble modified resin, 15-20 parts shrinkage modified filler, 2-5 parts photoinitiator, 0.5-3 parts pigment, 1-3 parts leveling agent and 15-25 parts solvent;

[0008] The alkali-soluble modified resin is prepared by the following steps:

[0009] A1. Place o-cresol epoxy resin, p-methoxyphenol and triphenylphosphine in a reaction vessel and stir. Heat the reaction vessel to 90-110℃, add acrylic acid dropwise, and react until the acid value is less than 5mgKOH / g. Cool to obtain phenolic epoxy acrylate intermediate.

[0010] A2. Place the phenolic epoxy acrylate intermediate in a nitrogen-protected reactor and stir. Heat the reactor to 80-95℃, add N,N-dimethylbenzylamine, tetrahydrophthalic anhydride and dodecyl succinic anhydride, and keep the reaction at this temperature for 3-5 hours to obtain the alkali-soluble modified resin.

[0011] Further, in step A1, the ratio of o-cresol epoxy resin, p-methoxyphenol, and triphenylphosphine is 8-10:0.02-0.04:0.01-0.02, and the molar amount of acrylic acid is 1.0-1.1 times the molar amount of epoxy groups in o-cresol epoxy resin; in step A2, the ratio of phenolic epoxy acrylate intermediate, N,N-dimethylbenzylamine, tetrahydrophthalic anhydride, and dodecyl succinic anhydride is 10-12:0.05-0.10:1-3:0.5-1.5.

[0012] Furthermore, the photoinitiator is one or more of 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and isopropylthioxanthone; the solvent is one or more of propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate, γ-butyrolactone, and N-methylpyrrolidone; the pigment is one or more of phthalocyanine green, phthalocyanine blue, carbon black, and titanium dioxide; and the leveling agent is one or two of polyether-modified polydimethylsiloxane and polyacrylate copolymer.

[0013] Furthermore, the anti-shrinkage modified filler is prepared by the following steps:

[0014] B1. Place nano-zirconium tungstate powder and Tris-HCl buffer solution in a reaction vessel and stir to disperse. Add dopamine hydrochloride and react at room temperature in the dark for 20-24 hours. Post-processing yields core-shell nanoparticle precursors.

[0015] B2. The core-shell nanoparticle precursor and toluene were placed in a reaction vessel under nitrogen atmosphere and stirred. Isoethyl methacrylate and dibutyltin dilaurate were slowly added. The reaction vessel was heated to 70-80℃ and kept at this temperature for 14-16 hours. The shrinkage-resistant modified filler was obtained after post-treatment.

[0016] Further, in step B1, the ratio of the nano-zirconium tungstate powder, Tris-HCl buffer solution, and dopamine hydrochloride is 8-10g:190-210mL:2-4g, the pH of the Tris-HCl buffer solution is 8.5±0.1, and the post-processing steps include: after the reaction is completed, the mixture is filtered, the filter cake is washed 2-4 times with deionized water and ethanol, transferred to an oven at 50-60℃, and dried for 4-6 hours to obtain the core-shell nanoparticle precursor.

[0017] Further, in step B2, the ratio of the core-shell nanoparticle precursor, toluene, isocyanate methacrylate, and dibutyltin dilaurate is 12-14g:110-130mL:2-3g:0.1-0.2g. The post-processing steps include: after the reaction is completed, filtration is performed, the filter cake is washed with toluene 2-4 times, transferred to an oven at 50-60℃, and dried to constant weight to obtain the anti-shrinkage modified filler.

[0018] Furthermore, the nano-zirconium tungstate powder is prepared by the following steps:

[0019] C1. Zirconium oxychloride, sodium tungstate and deionized water are placed in a reaction vessel and stirred. The reaction vessel is heated to 75-85℃, citric acid is added, and the mixture is kept warm and stirred for 5-10 min. Ammonia is added to adjust the pH to 3-4, and the reaction is kept warm for 4-6 h. The dry gel is obtained after post-treatment.

[0020] C2. Add the dry gel to a tube furnace and heat it to 600-650℃ in air at a rate of 3-5℃ / min. Calcine for 3-5 hours and then treat to obtain nano-zirconium tungstate powder.

[0021] Further, in step C1, the ratio of zirconium oxychloride, sodium tungstate, deionized water, and citric acid is 2-4g:5-7g:80-100mL:8-10g, and the concentration of ammonia is 20-25wt%. The post-processing step includes: after the reaction is completed, wait for the reaction system to cool to room temperature, transfer the reaction product to an oven at 110-120℃, and dry for 10-12 hours to obtain a dry gel.

[0022] Furthermore, in step C2, the post-processing step includes: after the reaction is completed, the reaction product is added to liquid nitrogen for rapid quenching treatment to obtain nano-zirconium tungstate powder.

[0023] The present invention also proposes a method for preparing a low-warpage solder resist ink material, comprising the following steps:

[0024] Step 1: Place the solvent, photoinitiator, and leveling agent in a high-speed homogenizer under yellow light environment, stir evenly, add alkali-soluble modified resin, pigment, and anti-shrinkage modified filler, and stir and disperse at 800-1200 rpm for 30-60 minutes to obtain ink premix.

[0025] Step 2: Add the ink premix to a three-roll mill for grinding. During the grinding process, cool water is introduced to control the roller temperature at 25-35℃. Grind 3-5 times and pass through a 200-400 mesh sieve to obtain low warpage solder resist ink material.

[0026] The present invention also proposes the application of a low warpage solder resist ink material, which is applied to the preparation of printed circuit boards.

[0027] The present invention has the following beneficial effects:

[0028] 1. This invention uses a modified resin containing long carbon aliphatic chains and alicyclic structures as a film-forming matrix. The long carbon chains are incorporated through semi-esterification modification, which expands the free volume of the polymer. The alicyclic structures maintain the mechanical properties of the system during buffering deformation. The two construct a synergistic internal plasticizing effect, which significantly improves the flexibility of the crosslinked segments. This design enables the ink coating to efficiently dissipate the internal stress generated by curing shrinkage during photo-crosslinking, suppress warping, and construct an anti-shrinkage resin network.

[0029] 2. This invention also introduces nano-zirconium tungstate anti-shrinkage filler with polydopamine coating and photosensitive double bonds grafted onto its surface. The negative thermal expansion characteristics of its core compensate for the curing volume shrinkage, while the shell and double bonds promote the filler to directly participate in photo-induced crosslinking. This synergistic interaction of physical volume compensation and chemical covalent anchoring avoids the phase separation and stress concentration defects induced by the agglomeration of inorganic fillers. The micro-internal stress is uniformly transmitted and deeply dissipated in the inorganic and organic covalent interpenetrating network, thereby endowing the ink material with excellent anti-warping deformation ability and high film density of the cured coating.

[0030] 3. This invention also relies on a multi-stage shearing and grinding process with light shielding and water-cooled temperature control. This dispersion process eliminates the risk of pre-crosslinking of active components, and achieves deep deagglomeration and high interface wetting of multiphase materials. It not only eliminates stress mutations induced by local crosslinking density differences, but also makes the crosslinking internal stress uniformly dissipated globally. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0032] The commercially available nano-silica used in this invention was purchased from Nangong Jiuxin New Material Technology Co., Ltd., with a particle size of 40-50nm.

[0033] The o-cresol epoxy resin used in this invention was purchased from Shandong Yiyi New Materials Co., Ltd., with the grade CYDCN-200 and brand name Baling Petrochemical.

[0034] Example 1

[0035] This embodiment provides a method for preparing anti-shrinkage modified filler, including the following steps:

[0036] Step I: Preparation of dry gel

[0037] Weigh out 20g of zirconium oxychloride, 50g of sodium tungstate and 800mL of deionized water and place them in a reaction vessel and stir. Heat the reaction vessel to 75℃, add 80g of citric acid, keep it warm and stir for 5min, add ammonia water to adjust the pH to 3, keep it warm and react for 4h. After the reaction is completed, wait for the reaction system to cool to room temperature, transfer the reaction product to an oven at 110℃ and dry for 10h to obtain a dry gel.

[0038] Step II: Preparation of nano-zirconium tungstate powder

[0039] The dry gel was added to a tube furnace and heated to 600°C at a rate of 3°C / min in air atmosphere. After calcination for 3 hours, the reaction product was added to liquid nitrogen for rapid cooling and quenching to obtain nano-zirconium tungstate powder.

[0040] Step III: Preparation of core-shell nanoparticle precursors

[0041] Weigh 80g of nano-zirconium tungstate powder and 1900mL of Tris-HCl buffer solution with pH 8.4 and place them in a reaction vessel. Stir and disperse the mixture. Add 20g of dopamine hydrochloride and react at room temperature in the dark for 20h. After the reaction is complete, filter the mixture. Wash the filter cake twice with deionized water and ethanol. Transfer the cake to an oven at 50℃ and dry it for 4h to obtain the core-shell nanoparticle precursor.

[0042] Step IV: Preparation of anti-shrinkage modified filler

[0043] Weigh 120g of core-shell nanoparticle precursor and 1100mL of toluene and place them in a reaction vessel under nitrogen atmosphere and stir. Slowly add 20g of isocyanate methacrylate and 1g of dibutyltin dilaurate. Heat the reaction vessel to 70℃ and keep it at that temperature for 14h. After the reaction is complete, filter the mixture and wash the filter cake twice with toluene. Transfer the cake to an oven at 50℃ and dry it to constant weight to obtain the anti-shrinkage modified filler.

[0044] First, using the sol-gel method, zirconium oxychloride and sodium tungstate are complexed with citric acid to form a gel. After high-temperature calcination and rapid quenching, a nano-zirconium tungstate core with negative thermal expansion characteristics is obtained. Subsequently, dopamine undergoes oxidative self-polymerization in a weakly alkaline buffer solution, forming a polydopamine shell rich in hydroxyl and amino groups on the core surface in situ. Finally, under organotin catalysis, the isocyanate groups in isocyanate methacrylate undergo a nucleophilic addition reaction with the hydroxyl and amino groups on the shell, covalently grafting photocurable carbon-carbon double bonds onto the filler surface to obtain a shrinkage-resistant modified filler.

[0045] The negative thermal expansion properties of nano-zirconium tungstate can intrinsically compensate for the volume shrinkage caused by the curing of ink matrix, reduce macroscopic internal stress to suppress deformation, and the polydopamine coating on its surface improves the interfacial wettability and dispersibility of the inorganic core in organic resin. At the same time, the photosensitive double bonds grafted at its ends end endow the filler with reactivity, enabling it to directly participate in photo-induced crosslinking and construct an inorganic-organic covalent interpenetrating network.

[0046] Example 2

[0047] This embodiment provides a method for preparing anti-shrinkage modified filler, including the following steps:

[0048] Step I: Preparation of dry gel

[0049] Weigh out 30g of zirconium oxychloride, 60g of sodium tungstate, and 900mL of deionized water and place them in a reaction vessel. Stir the vessel and heat it to 80℃. Add 90g of citric acid and stir for 7 minutes. Add ammonia to adjust the pH to 3.5 and keep the reaction vessel at this temperature for 5 hours. After the reaction is complete, wait for the reaction system to cool to room temperature and transfer the reaction product to an oven at 115℃. Dry for 11 hours to obtain a dry gel.

[0050] Step II: Preparation of nano-zirconium tungstate powder

[0051] The dry gel was added to a tube furnace and heated to 625°C at a rate of 4°C / min in air atmosphere. After calcination for 4 hours, the reaction product was added to liquid nitrogen for rapid quenching to obtain nano-zirconium tungstate powder.

[0052] Step III: Preparation of core-shell nanoparticle precursors

[0053] Weigh 90g of nano-zirconium tungstate powder and 2000mL of Tris-HCl buffer solution with pH 8.5 and place them in a reaction vessel. Stir and disperse the mixture. Add 30g of dopamine hydrochloride and react at room temperature in the dark for 22h. After the reaction is complete, filter the mixture. Wash the filter cake three times with deionized water and ethanol. Transfer the cake to an oven at 55℃ and dry it for 5h to obtain the core-shell nanoparticle precursor.

[0054] Step IV: Preparation of anti-shrinkage modified filler

[0055] Weigh 130g of core-shell nanoparticle precursor and 1200mL of toluene and place them in a reaction vessel under nitrogen atmosphere and stir. Slowly add 25g of isocyanate methacrylate and 1.5g of dibutyltin dilaurate. Heat the reaction vessel to 75℃ and keep it at that temperature for 15h. After the reaction is complete, filter the mixture and wash the filter cake three times with toluene. Transfer the cake to an oven at 55℃ and dry it to constant weight to obtain the shrinkage-resistant modified filler.

[0056] Example 3

[0057] This embodiment provides a method for preparing anti-shrinkage modified filler, including the following steps:

[0058] Step I: Preparation of dry gel

[0059] Weigh out 40g of zirconium oxychloride, 70g of sodium tungstate and 1000mL of deionized water and place them in a reaction vessel and stir. Heat the reaction vessel to 85℃, add 100g of citric acid, keep warm and stir for 10min, add ammonia water to adjust the pH to 4, keep warm and react for 6h. After the reaction is complete, wait for the reaction system to cool to room temperature, transfer the reaction product to an oven at 120℃ and dry for 12h to obtain a dry gel.

[0060] Step II: Preparation of nano-zirconium tungstate powder

[0061] The dry gel was added to a tube furnace and heated to 650°C at a rate of 5°C / min in air atmosphere. After calcination for 5 hours, the reaction product was added to liquid nitrogen for rapid quenching to obtain nano-zirconium tungstate powder.

[0062] Step III: Preparation of core-shell nanoparticle precursors

[0063] Weigh 100g of nano-zirconium tungstate powder and 2100mL of Tris-HCl buffer solution with pH 8.6 and place them in a reaction vessel. Stir and disperse the mixture. Add 40g of dopamine hydrochloride and react at room temperature in the dark for 24h. After the reaction is complete, filter the mixture. Wash the filter cake four times with deionized water and ethanol. Transfer the cake to an oven at 60℃ and dry it for 6h to obtain the core-shell nanoparticle precursor.

[0064] Step IV: Preparation of anti-shrinkage modified filler

[0065] Weigh 140g of core-shell nanoparticle precursor and 1300mL of toluene and place them in a reaction vessel under nitrogen atmosphere and stir. Slowly add 30g of isocyanate methacrylate and 2g of dibutyltin dilaurate. Heat the reaction vessel to 80℃ and keep it at that temperature for 16h. After the reaction is complete, filter the mixture and wash the filter cake 4 times with toluene. Transfer the cake to an oven at 60℃ and dry it to constant weight to obtain the shrinkage-resistant modified filler.

[0066] Example 4

[0067] This embodiment provides a method for preparing an alkali-soluble modified resin, comprising the following steps:

[0068] Step ①: Preparation of phenolic epoxy acrylate intermediate

[0069] Weigh out 80g of o-cresol epoxy resin, 0.2g of p-methoxyphenol and 0.1g of triphenylphosphine and place them in a reaction vessel and stir. Heat the reaction vessel to 90℃ and add acrylic acid dropwise at 1.0 times the molar amount of epoxy groups in o-cresol epoxy resin. React until the acid value is less than 5mgKOH / g and cool to obtain phenolic epoxy acrylate intermediate.

[0070] Step 2: Preparation of alkali-soluble modified resin

[0071] Weigh 100g of phenolic epoxy acrylate intermediate and place it in a nitrogen-protected reactor and stir. Heat the reactor to 80℃, add 0.5g of N,N-dimethylbenzylamine, 10g of tetrahydrophthalic anhydride and 5g of dodecyl succinic anhydride, and keep the reaction at this temperature for 3h to obtain an alkali-soluble modified resin.

[0072] Under the catalysis of triphenylphosphine, the carboxyl group of acrylic acid undergoes a ring-opening esterification reaction with the epoxy group of o-cresol epoxy resin, introducing a photocurable carbon-carbon double bond into the polymer backbone and generating a secondary hydroxyl group in situ to obtain a phenolic epoxy acrylate intermediate. Subsequently, the secondary hydroxyl group on the backbone of this intermediate undergoes a ring-opening half-esterification reaction with tetrahydrophthalic anhydride and dodecyl succinic anhydride. The side chain introduces free carboxyl groups through the ring-opening of the anhydride to provide the alkali solubility required for alkaline water development, and simultaneously incorporates alicyclic structures and long carbon chain aliphatic hydrocarbon groups, finally constructing a modified resin system with photopolymerization activity and alkali solubility and development characteristics.

[0073] The photosensitive double bonds introduced by acrylate esterification endow the backbone with photo-crosslinking activity, and the half-esterification modification enables alkaline water development through free carboxyl groups. The long carbon aliphatic chains and alicyclic structures that are simultaneously introduced form a synergistic internal plasticizing effect. The long carbon chains effectively increase the free volume of the polymer to dissipate the internal stress of photocuring shrinkage, while the alicyclic structure maintains the mechanical properties of the system while buffering deformation. This structural design significantly improves the flexibility of the crosslinked segments in the resin matrix and intrinsically suppresses the warping of the coating.

[0074] Example 5

[0075] This embodiment provides a method for preparing an alkali-soluble modified resin, comprising the following steps:

[0076] Step ①: Preparation of phenolic epoxy acrylate intermediate

[0077] Weigh out 90g of o-cresol epoxy resin, 0.3g of p-methoxyphenol and 0.15g of triphenylphosphine and place them in a reaction vessel and stir. Heat the reaction vessel to 100℃ and add acrylic acid dropwise at 1.05 times the molar amount of epoxy groups in o-cresol epoxy resin. React until the acid value is less than 5mgKOH / g and cool to obtain phenolic epoxy acrylate intermediate.

[0078] Step 2: Preparation of alkali-soluble modified resin

[0079] Weigh 110g of phenolic epoxy acrylate intermediate and place it in a nitrogen-protected reactor and stir. Heat the reactor to 90℃, add 0.75g of N,N-dimethylbenzylamine, 20g of tetrahydrophthalic anhydride and 10g of dodecyl succinic anhydride, and keep the reaction at this temperature for 4h to obtain an alkali-soluble modified resin.

[0080] Example 6

[0081] This embodiment provides a method for preparing an alkali-soluble modified resin, comprising the following steps:

[0082] Step ①: Preparation of phenolic epoxy acrylate intermediate

[0083] Weigh out 100g of o-cresol epoxy resin, 0.4g of p-methoxyphenol and 0.2g of triphenylphosphine and place them in a reaction vessel and stir. Heat the reaction vessel to 110℃ and add acrylic acid dropwise at 1.1 times the molar amount of epoxy groups in o-cresol epoxy resin. React until the acid value is less than 5mgKOH / g and cool to obtain phenolic epoxy acrylate intermediate.

[0084] Step 2: Preparation of alkali-soluble modified resin

[0085] Weigh 120g of phenolic epoxy acrylate intermediate and place it in a nitrogen-protected reactor and stir. Heat the reactor to 95℃, add 1g of N,N-dimethylbenzylamine, 30g of tetrahydrophthalic anhydride and 15g of dodecyl succinic anhydride, and keep the reaction at this temperature for 5h to obtain an alkali-soluble modified resin.

[0086] Example 7

[0087] This embodiment provides a method for preparing a low-warpage solder resist ink material, including the following steps:

[0088] Step 1: Preparation of ink premix

[0089] Weigh out 15 parts by weight of propylene glycol methyl ether acetate, 2 parts of 1-hydroxycyclohexylphenyl ketone and 1 part of polyether-modified polydimethylsiloxane and place them in a high-speed homogenizer under yellow light. Stir evenly, add 30 parts of the alkali-soluble modified resin prepared in Example 4, 0.5 parts of carbon black and 15 parts of the anti-shrinkage modified filler prepared in Example 1, and stir and disperse at 800 rpm for 30 min to obtain ink premix.

[0090] Step 2: Preparation of low-warpage solder resist ink material

[0091] The ink premix was added to a three-roll mill for grinding. Cooling water was introduced during the grinding process to control the roller temperature at 25°C. The mixture was ground three times and then passed through a 200-mesh sieve to obtain a low-warpage solder resist ink material.

[0092] Short-wave radiation is shielded under yellow light to inhibit photoinitiator decomposition and prevent photo-induced dark polymerization of resins containing double bonds. At the same time, high-speed shearing allows solid fillers and pigments to be initially dispersed in the organic continuous phase. Subsequently, the strong shearing and extrusion stress of a three-roll mill is used to deeply break down particle agglomerates, achieving high dispersion and interfacial wetting of the inorganic phase in the polymer matrix. The entire grinding process is water-cooled and temperature-controlled to eliminate mechanical frictional heat and prevent thermal cross-linking of highly active resins. Finally, the ink material is obtained through microporous sieving.

[0093] The synergistic effect of light shielding and water-cooled temperature control eliminates the pre-crosslinking risk of the system and ensures rheological stability. Multi-stage shearing and three-roll milling achieve deep deagglomeration of multiphase materials and high interface wetting, avoiding local crosslinking density differences and stress concentration induced by inorganic filler agglomeration. The highly uniform microstructure ensures uniform dissipation of internal stress during coating crosslinking. Combined with the high-density film-forming characteristics imparted by microporous sieving, the system's anti-warping dimensional stability is further enhanced through physical dispersion.

[0094] Example 8

[0095] This embodiment provides a method for preparing a low-warpage solder resist ink material, including the following steps:

[0096] Step 1: Preparation of ink premix

[0097] Weigh out 20 parts by weight of propylene glycol methyl ether acetate, 3.5 parts of 1-hydroxycyclohexylphenyl ketone and 2 parts of polyether-modified polydimethylsiloxane and place them in a high-speed homogenizer under yellow light. Stir evenly, add 40 parts of the alkali-soluble modified resin prepared in Example 5, 2 parts of carbon black and 17.5 parts of the anti-shrinkage modified filler prepared in Example 2, and stir and disperse at 1000 rpm for 45 min to obtain ink premix.

[0098] Step 2: Preparation of low-warpage solder resist ink material

[0099] The ink premix was added to a three-roll mill for grinding. Cooling water was introduced during the grinding process to control the roller temperature at 30°C. The mixture was ground four times and then passed through a 300-mesh sieve to obtain a low-warpage solder resist ink material.

[0100] Example 9

[0101] This embodiment provides a method for preparing a low-warpage solder resist ink material, including the following steps:

[0102] Step 1: Preparation of ink premix

[0103] Weigh out 25 parts by weight of propylene glycol methyl ether acetate, 5 parts of 1-hydroxycyclohexylphenyl ketone and 3 parts of polyether-modified polydimethylsiloxane and place them in a high-speed homogenizer under yellow light. Stir evenly, add 50 parts of the alkali-soluble modified resin prepared in Example 6, 3 parts of carbon black and 20 parts of the anti-shrinkage modified filler prepared in Example 3, and stir and disperse at 1200 rpm for 60 min to obtain ink premix.

[0104] Step 2: Preparation of low-warpage solder resist ink material

[0105] The ink premix was added to a three-roll mill for grinding. Cooling water was introduced during the grinding process to control the roller temperature at 35°C. The mixture was ground 5 times and then passed through a 400-mesh sieve to obtain a low-warpage solder resist ink material.

[0106] Comparative Example 1

[0107] The difference between this comparative example and Example 9 is that, in step one, when preparing the ink premix, commercially available nano-silica is used to replace the anti-shrinkage modified filler in an equal amount.

[0108] Comparative Example 2

[0109] The difference between this comparative example and Example 9 is that, in step one, when preparing the ink premix, nano-zirconium tungstate powder is used to replace the anti-shrinkage modified filler in an equal amount.

[0110] Comparative Example 3

[0111] The difference between this comparative example and Example 9 is that, in step ②, when preparing the alkali-soluble modified resin, the use of dodecyl succinic anhydride is omitted.

[0112] Performance testing:

[0113] Using copper-clad laminate as the substrate, the ink materials prepared in Examples 7-9 and Comparative Examples 1-3 were uniformly coated onto the substrate surface using a wire rod coater, with the wet film thickness controlled at 25 μm. The substrate was first pre-baked at 80°C for 30 min, and then cured using a UV curing machine with a light intensity of 800 mW / cm² and a cumulative exposure energy of 1200 mJ / cm². After curing at 150°C for 60 min, a test sample was obtained. The sample was then placed in an environment with a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5% for 24 h for later use.

[0114] The volume shrinkage rate of the ink materials prepared in Examples 7-9 and Comparative Examples 1-3 was tested according to the standard GB / T 13465.5-2009 "Test Method for Shrinkage Rate of Impermeable Graphite Phenolic Adhesives".

[0115] The ink material test samples prepared in Examples 7-9 and Comparative Examples 1-3 were placed naturally on a horizontal marble platform. Under no external load conditions, the vertical height difference between the four corners and the center of the sample relative to the platform was measured using a digital height gauge. The maximum value among the five measuring points was used to characterize the anti-warping ability of the ink material test sample.

[0116] The adhesion grades of the ink materials prepared in Examples 7-9 and Comparative Examples 1-3 were tested according to the standard GB / T 9286-2021 "Cross-cut test of paints and varnishes".

[0117] The hardness of the ink materials prepared in Examples 7-9 and Comparative Examples 1-3 was tested according to the standard GB / T 6739-2022 "Determination of Hardness of Paints and Varnishes by Pencil Method".

[0118] The ink material test samples prepared in Examples 7-9 and Comparative Examples 1-3 were placed in a molten solder bath at 288±5℃ and floated for 10 seconds. This was repeated 3 times. After cooling, the coating surface was observed and solder resistance was tested. The specific data are shown in Table 1 below.

[0119] Table 1 - Performance Test Data for Each Sample

[0120]

[0121] Data Analysis:

[0122] Analysis of the above table shows that the ink material prepared by this invention has a volume shrinkage rate of 1.86%, a warpage height of 0.15 mm, an adhesion grade of 0, and a hardness of 3H. Furthermore, it did not blister or peel off after passing the solderability test. All of these data are superior to those of the comparative example.

[0123] This invention prepares negative thermal expansion nano-zirconium tungstate using a sol-gel method combined with liquid nitrogen quenching. After polydopamine coating and grafting of photosensitive double bonds, an anti-shrinkage filler is obtained. Then, o-cresyl epoxy resin is acrylated and modified with dibasic anhydride to obtain an internally plasticized resin. Finally, the components are premixed under yellow light and water-cooled three-roll milling to obtain a low-warpage solder resist ink. This not only improves the anti-shrinkage and anti-warpage properties of the ink material, but also improves its mechanical properties.

[0124] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A low-warpage solder resist ink material, characterized in that, It comprises the following components by weight: 30-50 parts alkali-soluble modified resin, 15-20 parts shrinkage modified filler, 2-5 parts photoinitiator, 0.5-3 parts pigment, 1-3 parts leveling agent and 15-25 parts solvent; The alkali-soluble modified resin is prepared by the following steps: A1. Place o-cresol epoxy resin, p-methoxyphenol and triphenylphosphine in a reaction vessel and stir. Heat the reaction vessel to 90-110℃, add acrylic acid dropwise, and react until the acid value is less than 5mgKOH / g. Cool to obtain phenolic epoxy acrylate intermediate. A2. Place the phenolic epoxy acrylate intermediate in a nitrogen-protected reactor and stir. Heat the reactor to 80-95℃, add N,N-dimethylbenzylamine, tetrahydrophthalic anhydride and dodecyl succinic anhydride, and keep the reaction at this temperature for 3-5 hours to obtain the alkali-soluble modified resin.

2. The low warpage solder resist ink material according to claim 1, characterized in that, In step A1, the ratio of o-cresol epoxy resin, p-methoxyphenol, and triphenylphosphine is 8-10:0.02-0.04:0.01-0.02, and the molar amount of acrylic acid is 1.0-1.1 times the molar amount of epoxy groups in the o-cresol epoxy resin; in step A2, the ratio of phenolic epoxy acrylate intermediate, N,N-dimethylbenzylamine, tetrahydrophthalic anhydride, and dodecyl succinic anhydride is 10-12: 0.05-0.10:1-3:0.5-1.5。 3. The low warpage solder resist ink material according to claim 1, characterized in that, The photoinitiator is one or more of 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and isopropylthioxanthone; the solvent is one or more of propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate, γ-butyrolactone, and N-methylpyrrolidone; the pigment is one or more of phthalocyanine green, phthalocyanine blue, carbon black, and titanium dioxide; and the leveling agent is one or two of polyether-modified polydimethylsiloxane and polyacrylate copolymer.

4. The low warpage solder resist ink material according to claim 1, characterized in that, The anti-shrinkage modified filler is prepared by the following steps: B1. Place nano-zirconium tungstate powder and Tris-HCl buffer solution in a reaction vessel and stir to disperse. Add dopamine hydrochloride and react at room temperature in the dark for 20-24 hours. Post-processing yields core-shell nanoparticle precursors. B2. The core-shell nanoparticle precursor and toluene were placed in a reaction vessel under nitrogen atmosphere and stirred. Isoethyl methacrylate and dibutyltin dilaurate were slowly added. The reaction vessel was heated to 70-80℃ and kept at this temperature for 14-16 hours. The shrinkage-resistant modified filler was obtained after post-treatment.

5. The low warpage solder resist ink material according to claim 4, characterized in that, In step B1, the ratio of the nano-zirconium tungstate powder, Tris-HCl buffer solution, and dopamine hydrochloride is 8-10g:190-210mL:2-4g, and the pH of the Tris-HCl buffer solution is 8.5±0.1; in step B2, the ratio of the core-shell nanoparticle precursor, toluene, isocyanate methacrylate, and dibutyltin dilaurate is 12-14g:110-130mL:2-3g:0.1-0.2g.

6. The low warpage solder resist ink material according to claim 4, characterized in that, The nano-zirconium tungstate powder is prepared by the following steps: C1. Zirconium oxychloride, sodium tungstate and deionized water are placed in a reaction vessel and stirred. The reaction vessel is heated to 75-85℃, citric acid is added, and the mixture is kept warm and stirred for 5-10 min. Ammonia is added to adjust the pH to 3-4, and the reaction is kept warm for 4-6 h. The dry gel is obtained after post-treatment. C2. Add the dry gel to a tube furnace and heat it to 600-650℃ in air at a rate of 3-5℃ / min. Calcine for 3-5 hours and then treat to obtain nano-zirconium tungstate powder.

7. The low warpage solder resist ink material according to claim 6, characterized in that, In step C1, the ratio of zirconium oxychloride, sodium tungstate, deionized water and citric acid is 2-4g:5-7g:80-100mL:8-10g, and the concentration of ammonia is 20-25wt%.

8. A method for preparing a low-warpage solder resist ink material according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Place the solvent, photoinitiator, and leveling agent in a high-speed homogenizer under yellow light environment, stir evenly, add alkali-soluble modified resin, pigment, and anti-shrinkage modified filler, and stir and disperse at 800-1200 rpm for 30-60 minutes to obtain ink premix. Step 2: Add the ink premix to a three-roll mill for grinding. During the grinding process, cool water is introduced to control the roller temperature at 25-35℃. Grind 3-5 times and pass through a 200-400 mesh sieve to obtain low warpage solder resist ink material.

9. The application of a low-warpage solder resist ink material, characterized in that, The low warpage solder resist ink material as described in claims 1-7 is applied to the fabrication of printed circuit boards.

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