A single-component latent curing solder resist ink based on dynamic covalent chemistry regulation and a preparation method thereof

Abstract

The application provides a single-component latent curing solder resist ink based on dynamic covalent chemistry regulation and a preparation method thereof. The single-component latent curing solder resist ink comprises, in parts by weight, 30-70 parts of alkali-soluble photosensitive resin, 5-20 parts of heat-curing epoxy resin, 1-4 parts of latent epoxy curing agent microbeads with an imidazole-furfuryl structure, 2-10 parts of a photoinitiator, 1-3 parts of a photopolymerization monomer, 10-30 parts of a filler, 0.5-2 parts of an antifoaming agent, 0.5-2 parts of a pigment and 1-5 parts of a diluent. The application introduces a dynamic crosslinking network microcapsule structure based on a Diels-Alder reversible reaction, thereby significantly improving the storage stability of the imidazole latent curing agent in the single-component epoxy solder resist ink system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic packaging materials, especially relates to the high-end electronic manufacturing field such as high-density interconnection (HDI) printed circuit board, 5G communication substrate and power semiconductor packaging, and specifically relates to a one-component latent curing solder resist ink based on dynamic covalent chemistry regulation. BACKGROUND

[0002] With the rapid development of 5G communication, artificial intelligence and new energy vehicles, electronic packaging devices are accelerating towards high frequency, high integration and high reliability. In particular, in practical applications, solder resist materials for printed circuit boards need to withstand repeated thermal stress, resulting in excellent thermal stability and structural integrity in HAST (high temperature and high humidity accelerated test), TCT (cold and hot cycle test) and other reliability tests. Therefore, as the key protective layer on the surface of the packaging substrate, the solder resist ink directly determines the stable operation and signal transmission quality of the entire electronic device in terms of thermal mechanical properties, dielectric properties and long-term service reliability.

[0003] Currently, the mainstream solder resist ink usually adopts a two-component formulation system, that is, the A component (containing carboxyl resin, catalyst and functional filler) and the B component (containing thermosetting resin and active diluent) are packaged separately and mixed in proportion before use. Although this system has certain process adaptability, it still faces a series of inherent problems in practical applications: first, the two-component system requires high precision and uniformity of mixing, and manual dosing can easily lead to batch instability; second, air bubbles are easily introduced during on-site mixing, and the defoaming process is complex and affects the service life of the ink; third, the system has a short operation time window after mixing, and slight deviation in pre-baking conditions will seriously affect the development performance. These problems are particularly prominent in high-density and high-precision PCB mass production, and have become a key bottleneck restricting the further improvement of the industry.

[0004] To solve the above problems, in recent years, the research gradually shifts to the development of single-component latent curing solder resist ink system. Single-component epoxy system has become an indispensable key material in many high-end applications due to its convenience of use, consistent product quality, small environmental pollution and high production efficiency. Therefore, the core technology of single-component system lies in the use of latent curing agent, which should inhibit the reaction at room temperature and rapidly cure under elevated temperature conditions. This type of ink maintains long-term storage stability at room temperature by introducing a latent curing agent, and quickly releases activity during the heating curing process to complete the crosslinking reaction. The widely used latent curing agent includes dicyandiamide, imidazole and its derivatives, and the common strategies include physical coating (such as microencapsulation) or chemical modification (such as imidazole substituent regulation) to delay its reactivity. However, the physical coating method has the problem that it is difficult to completely remove the residual curing agent that is not completely coated, and these residues can significantly reduce the storage stability of the system; while the chemical modification improves the storage stability, but usually sacrifices the catalytic efficiency, resulting in incomplete curing reaction, decreased glass transition temperature of the cured product, and significantly deteriorated mechanical properties, which is difficult to meet the comprehensive performance requirements of high temperature, high frequency and high reliability in the new generation of high-end electronic packaging. Especially in the high-end fields of 5G communication, vehicle-mounted electronics and power semiconductors, more stringent technical indicators are put forward for solder resist ink materials. The traditional epoxy-imidazole system cannot realize the synergistic optimization of the above performances due to the mutual exclusion relationship of "storage stability-curing efficiency-mechanical properties / heat resistance".

[0005] In view of the contradiction between the process complexity of the two-component system and the demand for high-precision manufacturing, the reverse correlation between the storage stability and the curing reaction rate of the single-component system, and the inherent conflict between the high crosslinking density and the toughness improvement of the material, the present application aims to solve the problems of operation complexity, poor batch stability and difficulty in bubble control in the process application of the existing two-component solder resist ink system, especially the incomplete curing, T g decrease and kinetic performance deterioration caused by the contradiction between the storage stability and the catalytic efficiency of the imidazole latent curing agent in the existing single-component epoxy system. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application provides a single-component latent curing solder resist ink based on dynamic covalent chemistry regulation, which is based on a new strategy of imidazole latent curing regulated by Diels-Alder (DA) reversible reaction. By constructing a dynamic crosslinking network microcapsule composed of poly(imidazole monomer)-co-poly(furfuryl monomer) copolymer and bismaleimide, the reaction activity of imidazole is inhibited by both chemical and physical mechanisms during storage, and the thermal triggering release of imidazole catalytic activity is realized, thereby solving the problems raised in the above background art.

[0007] To achieve the above purpose, the present application is implemented by the following technical solutions:

[0008] According to a first aspect of the present application, a single-component latent curing solder resist ink based on dynamic covalent chemistry regulation is provided, comprising the following components by weight fraction:

[0009] 30~70 parts of alkali-soluble photosensitive resin;

[0010] 5~20 parts of heat-curing epoxy resin;

[0011] 1~4 parts of latent epoxy curing agent microbeads with imidazole-furfuryl structure;

[0012] 2~10 parts of photoinitiator;

[0013] 1~3 parts of photopolymerization monomer;

[0014] 10~30 parts of filler;

[0015] 0.5~2 parts of defoaming agent;

[0016] 0.5~2 parts of pigment;

[0017] 1~5 parts of diluent.

[0018] Preferably, the latent epoxy curing agent microbeads with imidazole-furfuryl structure are formed by microcapsule structure constructed by Diels-Alder reversible reaction of imidazole monomer-co-furfuryl monomer copolymer and bismaleimide to form a dynamic crosslinking network.

[0019] Further preferably, the D50 particle size of the latent epoxy curing agent microbeads with imidazole-furfuryl structure is 2~7 μm, and the imidazole blocking rate is >90%.

[0020] In the present application, the alkali-soluble photosensitive resin is selected from at least one of ortho-cresol formaldehyde epoxy resin, bisphenol A type epoxy resin, and acrylic epoxy resin.

[0021] Specifically, the ortho-cresol formaldehyde epoxy resin is selected from CCR-4959HW and / or CCR-4969HW;

[0022] The bisphenol A type epoxy resin is selected from resin CCR-1159HW;

[0023] The acrylic epoxy resin is selected from KPR-118 or KPR-236.

[0024] The heat-curing epoxy resin is selected from at least one of phenolic type epoxy resin, dinonylphenol type epoxy resin, bisphenol type epoxy resin, bisphenol phenolic type epoxy resin, and naphthalene type epoxy resin.

[0025] The photoinitiator is selected from at least one of TPO, ITX, 2-ethylanthraquinone, 369, 784, 651, 184, 907, and 819.

[0026] The photopolymerization monomer is selected from at least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, trimethylolpropane triacrylate, tripropylene glycol diacrylate, and pentaerythritol triacrylate.

[0027] The filler is selected from at least one of silicon powder, talc powder, fumed silica, and barium sulfate.

[0028] The defoaming agent is selected from a silicone defoaming agent, and specifically a silicone defoaming agent of type KS-66 produced by Nippon Shokubai Co., Ltd.

[0029] The pigment and diluent in the present application are selected from commonly known products.

[0030] According to a second aspect of the present application, a preparation method of a single-component latent curing solder resist ink based on dynamic covalent chemistry regulation is provided, including the following steps: first, mixing, dispersing, and grinding components of an imidazole-furfuryl structure latent epoxy curing agent microbead according to mass fraction to form a uniform slurry, then adding the imidazole-furfuryl structure latent epoxy curing agent microbead to the slurry, and stirring and homogenizing to obtain the single-component latent curing solder resist ink.

[0031] Specifically, the preparation method of the single-component latent curing solder resist ink based on dynamic covalent chemistry regulation is as follows:

[0032] S1, adding an alkali-soluble photosensitive resin, a thermally curing epoxy resin, a photoinitiator, a photopolymerization monomer, a filler, a defoaming agent, a pigment, and a diluent into a mixing container in sequence, and dispersing at a high speed of 1500-3000 rpm for 15-30 min to uniformly premix the components;

[0033] S2, grinding the premixed material obtained in step S1 by a three-roll mill to control the particle size of solid particles in the material to be less than 25 μm, and form a stable and uniform resin composition slurry;

[0034] S3, adding an imidazole-furfuryl structure latent epoxy curing agent microbead to the resin composition slurry, and stirring at a speed of 1500-3000 rpm for 15-30 min to improve the homogeneity and storage stability of the system, and obtain the single-component latent curing solder resist ink based on dynamic covalent chemistry regulation.

[0035] Preferably, the preparation method of the imidazole-furfuryl structure latent epoxy curing agent microbead is as follows:

[0036] (1) adding an initiator to a mixed solution containing an imidazole monomer, a furfuryl monomer and a diluent, and performing a polymerization reaction under nitrogen protection to generate an imidazole monomer-co-furfuryl monomer copolymer;

[0037] (2) dissolving the imidazole monomer-co-furfuryl monomer copolymer and a bismaleimide in an oil phase solvent, adding an aqueous solution containing an emulsifier, and performing an oil-in-water emulsification reaction at a first reaction temperature to obtain the latent type epoxy curing agent microbeads with an imidazole-furfuryl structure.

[0038] Preferably, in step (1), the imidazole monomer is selected from imidazole structure-containing acrylate compounds;

[0039] the furfuryl monomer is selected from furan structure-containing acrylate monomers;

[0040] the diluent is selected from at least one of anisole, p-methoxytoluene, phenetole, dimethoxybenzene, phenyl acetate, phenylacetone, methyl benzoate, benzyl alcohol, benzyl ether, benzyl alcohol, o-methoxytoluene, and o-methoxyphenethyl alcohol;

[0041] the initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptyl nitrile, dibenzoyl peroxide, and diisopropyl peroxydicarbonate.

[0042] Specifically, the imidazole monomer is selected from imidazole monomers represented by Formula I:

[0043] Formula I;

[0044] In Formula I, R1 is selected from H or CH3, R2 is selected from C1-C20 aliphatic straight chain or branched alkyl, R3 is selected from H or C1-C6 aliphatic straight chain or branched alkyl, and R4 is selected from H or C1-C6 aliphatic straight chain or branched alkyl.

[0045] the furfuryl monomer is selected from furfuryl monomers represented by Formula II:

[0046] Formula II;

[0047] In Formula II, R5 is selected from H or CH3, and CH6 is selected from C1-C20 aliphatic straight chain or branched alkyl.

[0048] In the preparation process of the latent curing agent microbeads, the ratio of the furan monomer to the imidazole monomer has a significant influence on the crosslinking density, thermal response performance and stability of the microbead structure of the curing system. If the proportion of the furan monomer is too low, the crosslinking degree of the system will be insufficient, which will make it difficult to support the formation of the spherical structure of the microbeads, resulting in unstable structure of the latent curing agent and affecting the dispersibility and use performance of the latent curing agent in the epoxy resin. Preferably, in step (1), the mass ratio of the imidazole monomer to the furfuryl monomer is 1:0.5-3.

[0049] The diluent accounts for 100-500% of the total mass of the monomers, and the initiator accounts for 0.05-5% of the total mass of the monomers.

[0050] Preferably, in step (2), the bismaleimide is selected from N, N' -methylene bismaleimide, N, N' -p-phenylene bismaleimide, N, N' -diphenylmethane bismaleimide, N, N' -hexamethylene bismaleimide, N, N' -dicyclohexylmethane bismaleimide, N, N' -di(trishydroxymethylpropane) bismaleimide, N, N' -diphenylstyrene bismaleimide, N, N' -bis(aminoethyl) ether bismaleimide, N, N' -di(hydroxyethyl) ethylenediamine bismaleimide, N， N’ -di(hydroxypropyl) propylenediamine bismaleimide, Figure 1 -dimethyl-p-phenylenediamine bismaleimide, at least one of a siloxane structure bismaleimide, a polyether type bismaleimide and a fluorine-containing bismaleimide. Preferably, in step (2), the mass ratio of the imidazole monomer-co-furfuryl monomer copolymer to the bismaleimide is 1:0.1-2.

[0051] The type and amount of the emulsifier have a key influence on the preparation process of the latent curing agent microbeads. If the emulsifier is not properly selected or the addition ratio is not appropriate, it is easy to cause the particle size of the microbeads to be too large and the particle size distribution to be uneven, thereby affecting the dispersion stability of the microbeads in the solder resist ink and the photosensitive performance of the film layer. If the particle size of the microbeads is too large, it is also easy to cause the development of the coating to be blurred and the pattern resolution to be reduced, and in severe cases, it can cause incomplete exposure and development, thereby restricting the formation precision of the fine lines.

[0052] Preferably, in step (2), the emulsifier is selected from the OP series emulsifiers, the MOA series emulsifiers, the AEO series emulsifiers and the Tween series emulsifiers.

[0053] Specifically, the OP series emulsifiers are selected from at least one of OP-9, OP-10 and OP-15; the MOA series emulsifiers are selected from at least one of MOA-7, MOA-9, MOA-15, MOA-20 and MOA-23; the AEO series emulsifiers are selected from at least one of AEO-7, AEO-9, AEO-15 and AEO-23; and the Tween series emulsifiers are selected from at least one of Tween-20, Tween-40, Tween-60, Tween-80 and Tween-85.

[0054] Preferably, the mass ratio of the oil phase solvent to the water phase solution containing the emulsifier is 1:2-3, and the mass concentration of the emulsifier in the water phase solution containing the emulsifier is 1.5-2.0 wt%.

[0055] Preferably, in step (1), the temperature of the polymerization reaction is 20-100℃, the stirring speed is 150-200 rpm, and the time is 30-45 min.

[0056] In step (2), the temperature of the first reaction temperature is 20-100℃, the stirring speed is 150-200 rpm, and the time is 30-45 min.

[0057] The oil-in-water emulsion reaction is treated by high-speed homogenization, and the time is 2-5 min.

[0058] Specifically, the preparation method of the imidazole-furfuryl structure latent epoxy curing agent microbeads in the application is as follows: (1) a diluent is added into a reaction kettle, after warming, an initiator, an imidazole monomer, a furfuryl monomer and nitrogen gas are sequentially added for deoxygenation, and then stirring reaction is performed to obtain a poly(imidazole monomer)-co-poly(furfuryl monomer) random copolymer solution as an initial product; when a predetermined reaction time is reached, the polymerization reaction is terminated by cooling and exposure to air; and the obtained polymer solution is precipitated three times with a poor solvent to remove unreacted monomers;

[0059] (2) the poly(imidazole monomer)-co-poly(furfuryl monomer) copolymer obtained in step (1) is dissolved in an oil solvent, an aqueous solution containing an emulsifier is added as a dispersed phase, the temperature is increased to a first reaction temperature for stirring reaction, oil-in-water emulsion treatment is performed to generate a uniform emulsion system, and then the microbead solid is collected by medium-speed filtration or vacuum suction filtration after natural cooling, and the drying temperature is not higher than 50℃; the obtained curing agent microbead has excellent thermal stability and latency, the particle size D 50 is 2-7 μm, the imidazole blocking rate is greater than 90%, and the microbead can be stably stored for more than 3 months at room temperature.

[0060] The poor solvent in step (1) is at least one of hexane, n-pentane, isopentane, heptane, isopentane, cyclohexane, petroleum ether, and naphtha.

[0061] The application provides a single-component latent curing solder resist ink based on dynamic covalent chemistry regulation and a preparation method thereof.

[0062] (1) The single-component latent curing solder resist ink based on dynamic covalent chemistry regulation provided in the scheme significantly improves the storage stability of an imidazole latent curing agent in a single-component epoxy solder resist ink system by introducing a dynamic crosslinking network microcapsule structure constructed based on a Diels-Alder reversible reaction.

[0063] (2) The single-component latent curing solder resist ink based on dynamic covalent chemistry regulation provided in the scheme realizes chemical passivation and physical coating of imidazole activity in cooperation through a heat-responsive crosslinking network formed between poly(imidazole monomer)-co-poly(furfuryl monomer) and bismaleimide, effectively overcomes the problems that traditional physical coating is difficult to completely wrap and chemical modification reduces the catalytic efficiency, realizes long-term storage without curing at room temperature, and releases the catalytic activity quickly under heating conditions, so that high storage stability and high curing efficiency are realized, and the requirements of high frequency, high density, and high reliability electronic packaging materials on multiple performance indicators such as thermal stability, mechanical strength, and reliability are met. BRIEF DESCRIPTION OF DRAWINGS

[0064] Figure 1 An electron microscope graph of the latent epoxy curing agent microbead with an imidazole-furfuryl structure prepared in Example 1 of the application at 20 mu m. DETAILED DESCRIPTION

[0065] The technical solutions in the embodiments of the application will be described clearly and completely in combination with the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0066] In the application, all raw materials can be purchased from the market or commonly used in the industry, and the methods in the following embodiments are all conventional methods in the field, unless otherwise specified.

[0067] In order to better illustrate the content of the application, the following specific embodiments are combined for description.

[0068] Example 1

[0069] In a three-neck flask equipped with stirring device, temperature control system and nitrogen protection, 50 g of anisole was added as diluent, heated to 80°C, and then 0.5 g of azobisisobutyronitrile was added as initiator, 15 g of imidazole monomer (structure as shown in formula I, R1=CH3, R2=C2H4, R3=H, R4=H) and 35 g of furfuryl acrylate (structure as shown in formula II, R5=H, R6=C1) were added under stirring, and then deoxygenated by nitrogen and reacted for 6 h under constant temperature. After cooling, the reaction was seeded and the reaction liquid was dropped into 300 mL of cooled hexane for precipitation, and the precipitation was repeated three times to obtain imidazole monomer-co-furfuryl monomer copolymer;

[0070] 10 g of imidazole monomer-co-furfuryl monomer copolymer and 5 g of N,N'-methylene bis-maleimide were dissolved in 30 mL of trichloroethylene to form an oil phase, which was slowly dropped into 90 mL of water phase with a mass concentration of 1.5 wt% AEO-9 emulsifier, and then treated in a 8000 rpm homogenizer for 3 min to generate stable oil-in-water emulsion. The emulsion was stirred at 60°C for 30 min, and then filtered at medium speed after cooling to room temperature. The microbead solid was collected and dried at low temperature below 50°C for 24 h to obtain a light yellow solid powder, i.e. latent epoxy curing agent microbeads with imidazole-furfuryl structure, as shown in ​ .

[0071] The prepared latent epoxy curing agent microbeads with imidazole-furfuryl structure were tested by particle size analyzer, and the D 50 particle size was 3.5 μm, the imidazole active blocking rate was 92%, and the DSC test showed that the pyrolysis starting temperature was 120°C. No reaction starting phenomenon was observed after sealing and storing at room temperature for 3 months.

[0072] Example 2

[0073] In a 500 mL three-neck flask, 60 g of anisole was added as diluent, heated to 75°C, and then 0.25 g of azobisisobutyronitrile initiator was added, followed by 25 g of imidazole monomer (structure as shown in formula I, R1=CH3, R2=C2H4, R3=H, R4=H) and 25 g of furfuryl acrylate (structure as shown in formula II, R5=H, R6=C1). After deoxygenation by nitrogen for 30 min, the reaction was carried out under constant temperature and stirring for 5 h. After the reaction was completed, the reaction liquid was quickly cooled and the polymerization reaction was terminated. The obtained reaction liquid was dropped into 250 mL of cooled heptane for precipitation, and the unreacted monomer oligomers were removed after repeated washing three times, and then filtered and vacuum dried to obtain imidazole monomer-co-furfuryl monomer copolymer;

[0074] Take 10 g of imidazole monomer-co-furfuryl monomer copolymer and 5 g of N,N'-diphenylmethane bismaleimide dissolved in 25 mL of 1,2-dichloroethane to obtain an oil phase, slowly add the oil phase to a 75 mL aqueous solution containing 2.0 wt% Tween-80, use a homogenizer to process at 8000 rpm for 3 min, generate a stable and uniform emulsion, react at 65°C under nitrogen protection for 45 min, cool to room temperature, filter and dry at low temperature to obtain light yellow curing agent microbeads, i.e. latent epoxy curing agent microbeads with imidazole-furfuryl structure.

[0075] The prepared latent epoxy curing agent microbeads with imidazole-furfuryl structure are tested by a particle size analyzer, and the D 50 The particle size is 4.2 μm, the imidazole active blocking rate is 90%, the DSC test shows that the pyrolysis starting temperature is 135°C, and no reaction starting phenomenon is observed after sealing storage at room temperature for 3 months, and the active is stable.

[0076] Application Example 1

[0077] A one-component latent curing solder resist ink based on dynamic covalent chemistry regulation, by weight fraction, including 34 parts of o-cresol formaldehyde epoxy resin (including 17 parts of CCR-4959HW and 17 parts of CCR-4969HW), 15 parts of phenolic epoxy resin (including 7 parts of DEN431 and 8 parts of N870-75EA), 8 parts of photoinitiator (including 6 parts of TPO and 2 parts of 369), 4 parts of photopolymerization monomer (including 2 parts of TMPTA and 2 parts of TPGDA), 1 part of KS-66 defoamer, 14 parts of filler (including 7 parts of silicon dioxide and 7 parts of barium sulfate), 1 part of phthalocyanine blue, 3 parts of imidazole-furfuryl structure latent epoxy curing agent microbeads prepared in Example 1 and 1 part of DCAC diluent.

[0078] Application Example 2

[0079] A one-component latent curing solder resist ink based on dynamic covalent chemistry regulation, by weight fraction, including 34 parts of alkali-soluble photosensitive resin (including 17 parts of CCR-4959HW and 17 parts of KPR-118), 15 parts of phenolic epoxy resin (including 7 parts of DEN431 and 8 parts of N870-75EA), 8 parts of photoinitiator (including 4 parts of TPO and 4 parts of ITX), 4 parts of photopolymerization monomer (including 2 parts of TMPTA and 2 parts of PETA), 1 part of KS-66 defoamer, 14 parts of filler (including 7 parts of silicon dioxide and 7 parts of barium sulfate), 1 part of phthalocyanine blue, 3 parts of imidazole-furfuryl structure latent epoxy curing agent microbeads prepared in Example 1 and 1 part of DCAC diluent.

[0080] Application Example 3

[0081] A single-component latent curing solder resist ink based on dynamic covalent chemistry regulation, comprising, by weight fraction, 34 parts of alkali-soluble photosensitive resin (including 17 parts of CCR-4959HW and 17 parts of KPR-118), 15 parts of phenolic epoxy resin (including 7 parts of DEN431 and 8 parts of N870-75EA), 8 parts of photoinitiator (including 4 parts of TPO and 4 parts of ITX), 4 parts of photopolymerization monomer (including 2 parts of TMPTA and 2 parts of PETA), 1 part of KS-66 defoamer, 14 parts of filler (including 7 parts of silicon dioxide and 7 parts of barium sulfate), 1 part of phthalocyanine blue, 3 parts of imidazole-furfuryl structure latent epoxy curing agent microbeads prepared in Example 2, and 1 part of DCAC diluent.

[0082] Comparative Example 1

[0083] A solder resist ink, comprising, by weight fraction, 34 parts of alkali-soluble photosensitive resin (including 17 parts of CCR-4959HW and 17 parts of KPR-118), 15 parts of phenolic epoxy resin (including 7 parts of DEN431 and 8 parts of N870-75EA), 8 parts of photoinitiator (including 4 parts of TPO and 4 parts of ITX), 4 parts of photopolymerization monomer (including 2 parts of TMPTA and 2 parts of PETA), 1 part of KS-66 defoamer, 14 parts of filler (including 7 parts of silicon dioxide and 7 parts of barium sulfate), 1 part of phthalocyanine blue, and 1 part of DCAC diluent.

[0084] The performance tests were carried out on Application Examples 1-3 and Comparative Example 1, respectively.

[0085] Storage stability: The prepared ink samples were respectively packaged in sealed glass bottles and stored at room temperature in a light-proof environment at 25±2℃, and samples were taken for testing at 0, 7, 14, 30, 60 and 90 days, respectively. The test contents included: observation of whether there were delamination, precipitation, flocculation or color change; using a WVS-2M type viscometer, 30 rpm, No. 3 rotor to determine the rotational viscosity; and evaluating the exposure and development performance by observing the pattern resolution and boundary definition. If the ink did not show obvious physical changes within 90 days, the viscosity fluctuation was not more than ±10%, and the development performance remained stable, it was determined that the single-component ink system had good storage stability.

[0086] Heat resistance: The prepared ink samples were applied to the surface-treated copper-clad substrate by screen printing, and the surface was pretreated with CZ8101B reagent for roughening treatment at an etching rate of 1.0 μm / min to form a uniform coating. After coating, the sample was pre-baked at 80℃ for 30 min without air bubbles, and then the bulk of the sample was determined by DMA exposure. Then, 30℃, 1% Na2CO3 aqueous solution, spray pressure 2kg / cm 2Conditioned for 60s, the unexposed area was removed, and the developed sample was treated by UV conveyor, the cumulative light energy was 2000mJ / cm2, to complete the photocuring pre-crosslinking process, finally heat cured in 170℃ hot air circulation oven for 60min, to form a dense resist film.

[0087] After curing, the glass film layer was tested for its thermal mechanical properties by DMA (dynamic mechanical analyzer), the glass transition temperature (Tg) of the solder resist film was determined by the peak temperature of tan delta, to evaluate the thermal stability and curing degree of the system, the test results are shown in Table 1.

[0088] Table 1

[0089]

[0090] From the data in Table 1, it can be seen that the thermal responsive crosslinking network formed between the imidazole monomer-co-furfuryl monomer and the bismaleimide realizes the chemical passivation and physical coating of imidazole activity synergistically, effectively overcomes the problems that the traditional physical coating is difficult to completely wrap and the chemical modification reduces the catalytic efficiency, realizes long-term storage without curing at room temperature, and releases the catalytic activity quickly under heating conditions, so as to realize the consideration of high storage stability and high curing efficiency, and meets the requirements of high frequency, high density and high reliability electronic packaging materials on multiple performance indicators such as thermal stability, mechanical strength and reliability.

[0091] Although the embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A one-component latent cure soldermask ink based on dynamic covalent chemistry regulation, characterized in that: By weight parts, including the following components: 30~70 parts of alkali-soluble photosensitive resin; 5~20 parts of thermally cured epoxy resin; 1~4 parts of imidazole-furfuryl structure of latent epoxy curing agent microbeads; 2~10 parts of photoinitiator; 1~3 parts of photopolymerization monomer; 10~30 parts of filler; 0.5~2 parts of defoaming agent; 0.5~2 parts of pigment; 1~5 parts of diluent; Wherein, the imidazole-furfuryl structure of latent epoxy curing agent microbeads is formed by the microcapsule structure of the dynamic crosslinking network of imidazole monomer-co-furfuryl monomer copolymer and bismaleimide through Diels-Alder reversible reaction.

2. A one-component latent curing resist ink based on dynamic covalent chemistry regulation according to claim 1, characterized in that: The D50 particle size of the imidazole-furfuryl structure of latent epoxy curing agent microbeads is 2~7μm, and the imidazole blocking rate is >90%.

3. A process for the preparation of a one-component latent cure solder mask ink based on dynamic covalent chemistry regulation according to any one of claims 1 to 2, characterized in that: Including the following steps: First, mix, disperse, grind the components except the imidazole-furfuryl structure of latent epoxy curing agent microbeads according to the mass fraction, form a uniform slurry, then add the imidazole-furfuryl structure of latent epoxy curing agent microbeads to the slurry, and stir homogeneously to obtain a single-component latent curing solder mask ink.

4. A method of preparing a one-component latent cure solder resist ink based on dynamic covalent chemistry regulation according to claim 3, characterized in that: The preparation method of the imidazole-furfuryl structure of latent epoxy curing agent microbeads is: (1) Add an initiator to a mixed solution containing imidazole monomer, furfuryl monomer and diluent, and carry out polymerization reaction under nitrogen protection to generate imidazole monomer-co-furfuryl monomer copolymer; (2) Dissolve the imidazole monomer-co-furfuryl monomer copolymer and bismaleimide in an oil phase solvent, then add an aqueous solution containing an emulsifier, heat to a first reaction temperature, and then carry out an oil-in-water emulsification reaction to obtain the imidazole-furfuryl structure of latent epoxy curing agent microbeads.

5. A method of preparing a one-component latent cure solder resist ink based on dynamic covalent chemistry regulation according to claim 4, characterized in that: In step (1), the imidazole monomer is selected from imidazole-containing acrylate compounds; The furfuryl monomer is selected from furan-containing acrylate monomers; The diluent is selected from at least one of anisole, p-methoxytoluene, phenetol, dimethoxybenzene, phenyl acetate, phenylacetone, methyl benzoate, benzyl alcohol, benzyl ether, benzyl alcohol, o-methoxytoluene, o-methoxyphenethyl alcohol; The initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptyl nitrile, dibenzoyl peroxide, and diisopropyl peroxydicarbonate.

6. A method of preparing a one-component latent cure solder resist ink based on dynamic covalent chemistry regulation according to claim 4, characterized in that: In step (1), the mass ratio of the imidazole monomer to the furfuryl monomer is 1:0.5~3; The diluent accounts for 100~500% of the total mass of the monomers, and the initiator accounts for 0.05~5% of the total mass of the monomers.

7. A method of preparing a one-component latent cure solder mask ink based on dynamic covalent chemistry regulation according to claim 4, characterized by: In step (2), the mass ratio of the imidazole monomer-co-furfuryl monomer copolymer to bismaleimide is 1:0.2~2.

8. A method of preparing a one-component latent cure solder resist ink based on dynamic covalent chemistry regulation according to claim 4, characterized by: In step (2), the emulsifier is selected from OP series emulsifiers, MOA series emulsifiers, AEO series emulsifiers, and Tween series emulsifiers; The mass ratio of the oil phase solvent to the aqueous solution containing the emulsifier is 1:2~3, and the mass concentration of the emulsifier in the aqueous solution containing the emulsifier is 1.5~2.0wt%.

9. A method of preparing a one-component latent cure solder resist ink based on dynamic covalent chemistry regulation according to claim 4, characterized in that: In step (1), the temperature of the polymerization reaction is 20-100℃, the stirring speed is 150-200 rpm, and the time is 30-45 min; In step (2), the temperature of the first reaction is 20-100℃, the stirring speed is 150-200 rpm, and the time is 30-45 min; The oil-in-water emulsification reaction is treated by high-speed homogenization, and the time is 2-5 min.

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