High purity sma copolymer blend for circuit boards and method of making

Abstract

The application provides a high-purity SMA copolymerized and blended material for a circuit board and a preparation method thereof, relates to the technical field of polymer materials and electronic chemicals, and is prepared by blending semi-esterification modified terpolymer resin, epoxy resin, photoinitiator, photocrosslinking monomer, functional filler, additive and organic solvent; the N-substituted maleimide monomer such as NPMI / FPMI is introduced into the copolymer main chain to form a rigid imide ring; the intrinsic Tg of the terpolymer resin can be significantly increased from 100-150 DEG C of common SMA binary copolymer to 160-240 DEG C, so that the high-temperature requirements of lead-free soldering and multi-layer pressing are met, and the technical problems that the existing SMA resin is applied to the high-end ink and the hole resin of the PCB and is insufficient in heat resistance, lacks intrinsic photosensitivity, has high metal ion residue, and is only suitable for a single scene are solved.

Description

Technical Field

[0001] This invention relates to the field of interdisciplinary technology of polymer materials and electronic chemicals, and in particular to a high-purity SMA copolymer blend material for circuit boards and its preparation method. Background Technology

[0002] With the rapid development of 5G communication, artificial intelligence, autonomous driving, and high-speed computing, printed circuit boards (PCBs) are evolving towards high-density interconnect (HDI), high frequency and high speed, and ultra-high reliability. This places increasingly stringent requirements on various functional inks and resin materials used in PCB manufacturing: higher glass transition temperature (Tg), lower dielectric constant (Dk) and dielectric loss (Df), better adhesion, lower curing shrinkage, and electronic-grade high purity with extremely low metal ion content.

[0003] Styrene-Maleic Anhydride Copolymer (SMA) is widely used in the field of epoxy curing agents for copper-clad laminates (CCLs) due to the presence of highly reactive anhydride groups in its molecular chain. This allows it to cure with epoxy resins without producing polar hydroxyl groups, resulting in cured products with low dielectric constant, low hygroscopicity, and good heat resistance. However, when directly applying SMA resin systems to demanding applications such as PCB circuit inks, selective inks, solder resist inks, and via-filling resins, existing SMA binary copolymers still exhibit the following significant shortcomings:

[0004] (1) Insufficient heat resistance: The glass transition temperature (Tg) of ordinary SMA binary copolymer is usually only 100-150℃. In lead-free soldering peak temperature ≥260℃ and multiple reflow soldering processes, the resin layer is prone to softening and thermal degradation, causing the solder resist layer to crack and the circuit ink to fall off.

[0005] (2) Single function: SMA binary copolymers rely solely on anhydride groups as epoxy curing sites, lacking photosensitive groups, alkali-soluble groups and toughening structures in synergistic design; in order to achieve photocuring and alkali development, post-modification esterification is usually required to introduce acrylate groups; this post-modification process is difficult to control precisely, and free anhydride is easily left behind, which degrades the storage stability of the resin.

[0006] (3) Purity does not meet electronic grade standards: residual monomers, initiator fragments, and metal catalyst residues in SMA resins prepared by conventional solution polymerization and bulk polymerization. + K + Fe 2+ Cu 2+High impurity content; in the electric field-humid heat coupling environment of PCB service, ionic impurities migrate, causing a decrease in insulation resistance, CAF failure, and electrochemical migration (ECM), which seriously reduces the long-term reliability of the circuit board.

[0007] (4) Wide molecular weight distribution and poor batch stability: Traditional free radical polymerization to prepare SMA results in a polydispersity index (PDI) > 2.5, with low molecular weight components and high molecular weight components coexisting, leading to large batch fluctuations in resin solubility, development performance and mechanical properties of the product.

[0008] Existing related patented technologies:

[0009] CN111333782A discloses a modified styrene-maleic anhydride resin, which uses hydroxyl acrylate and epoxy acrylate to post-modify binary SMA and is applied to white solder resist ink. This patent is a two-step process of polymerization followed by modification, and does not involve in-situ ternary copolymerization. The research focuses on high reflectivity of white solder resist.

[0010] CN114085308A discloses an oleophilic styrene-maleic anhydride copolymer, which introduces a small amount of high Tg monomer to complete the ternary copolymerization and adopts a solvent-free tubular continuous process; however, the proportion of the third monomer added is low, and the Tg improvement is limited, only 150-170℃. Its application is positioned as an epoxy curing agent for copper clad laminates, and it has not been developed for circuit inks, selective inks, or via-filling resins.

[0011] CN113388062A discloses St-MA-third monomer anhydride type oligomers with molecular weight of 1000-10000, for use in general UV-curable coatings and inks, but without specific optimization for high purity indicators and multi-scenario adaptability in PCB manufacturing processes.

[0012] US5296334A (MacDermid) discloses a photocurable solder resist composition based on partial esterification of SMA. The matrix is ​​a binary SMA copolymer, and photocurable groups are introduced through partial esterification of hydroxyalkyl acrylate and monohydric alcohol. There is no ternary copolymerization to improve heat resistance, nor are there any means of controlling electronic-grade purity.

[0013] US6509414B2 (Isola) discloses an SMA+epoxy+brominated bisphenol A co-crosslinking system for PCB laminates, targeting copper-clad laminates, which uses a halogen-containing flame-retardant system, thus not conforming to the trend of halogen-free environmental protection.

[0014] CN121718212A (Changyu) discloses a via-filling solder resist ink with an SMA content of 10-20%. The substrate is ordinary binary SMA, Tg≤150℃, and the lowest Dk is only 3.10 under 40GHz conditions, which limits the performance improvement potential.

[0015] In summary, there is an urgent need in this field to develop SMA copolymer blends that simultaneously possess high heat resistance, photosensitive / alkali-developable properties, electronic-grade high purity, and adaptability to multiple scenarios, in order to meet the comprehensive performance requirements of next-generation PCB circuit inks, selective inks, solder resist inks, and via-filling resins. Summary of the Invention

[0016] This invention relates to a high-purity SMA copolymer blend material for circuit boards and its preparation method, which solves the technical problems of insufficient heat resistance, lack of intrinsic photosensitivity, high metal ion residue, and suitability only for a single application when existing SMA resins are used in high-end PCB inks and via-filling resins.

[0017] This invention provides a high-purity SMA copolymer blend material for circuit boards, which is prepared by blending a semi-esterified modified ternary copolymer resin, an epoxy resin, a photoinitiator, a photocrosslinking monomer, a functional filler, additives, and an organic solvent.

[0018] By weight, the proportions of each blend component are as follows: 100 parts of semi-esterified modified terpolymer resin, 10-50 parts of epoxy resin, 1-10 parts of photoinitiator, 5-30 parts of photocrosslinking monomer, 5-80 parts of functional filler, 0.1-5 parts of additives, and the amount of organic solvent required to adjust the viscosity of the system.

[0019] The semi-esterified modified ternary copolymer resin is first obtained by controlled free radical polymerization of styrene, maleic anhydride and N-substituted maleimide functional monomers to obtain a ternary copolymer matrix resin, which is then semi-esterified by (meth)acrylate hydroxy ester, and then subjected to precipitation purification and ion exchange post-treatment.

[0020] The monomer composition of the terpolymer matrix resin prepared by molar percentage is: 35-70 mol% styrene, 20-50 mol% maleic anhydride, and 5-30 mol% N-substituted maleimide functional monomers.

[0021] Furthermore, the N-substituted maleimide functional monomer is selected from one or more of N-phenylmaleimide, N-(4-fluorophenyl)maleimide, N-(4-hydroxyphenyl)maleimide, and N-cyclohexylmaleimide.

[0022] Furthermore, the semi-esterification modification involves ring-opening esterification of 10-70 mol% of anhydride groups in the terpolymer matrix resin with (meth)acrylate hydroxy ester.

[0023] Furthermore, the (meth)acrylate hydroxy ester is selected from one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and pentaerythritol triacrylate.

[0024] Furthermore, the epoxy resin is selected from at least one of bisphenol A type epoxy, bisphenol F type epoxy, phenolic epoxy, o-cresol phenolic epoxy, and triglycidyl isocyanurate.

[0025] Furthermore, the functional filler is selected from at least one of silica, barium sulfate, alumina, boron nitride, and talc.

[0026] Furthermore, the additive is selected from at least one of defoamers, leveling agents, dispersants, and thixotropic agents.

[0027] A method for preparing a high-purity SMA copolymer blend for circuit boards includes the following steps:

[0028] Step 1: Ternary copolymerization:

[0029] Under an inert atmosphere, styrene, maleic anhydride, and N-substituted maleimide functional monomers are dissolved in an organic solvent, a free radical initiator is added, and solution polymerization is carried out at 60-120℃ for 2-12 hours to obtain a terpolymer matrix resin solution.

[0030] Step 2, Semi-esterification Modification:

[0031] (Meth)acrylate hydroxy ester, polymerization inhibitor and esterification catalyst were added to the terpolymer matrix resin solution and reacted at 60-100℃ for 2-8h. The esterification rate was controlled by monitoring the degree of weakening of the characteristic peak of the acid anhydride by infrared spectroscopy, and a semi-esterified modified resin solution was obtained.

[0032] Step 3: Precipitation and purification:

[0033] The semi-esterified modified resin solution was added dropwise to a deionized water / methanol mixed precipitant to precipitate the solid, which was then filtered, washed, and vacuum dried at 40-60℃.

[0034] Step 4: Ion exchange purification:

[0035] The dried solid is redissolved in an organic solvent, and then filled with H... + Type I strong acid cation exchange resin and OH - A mixed-bed ion exchange column of strong base anion exchange resin was used to collect the effluent and remove the solvent to obtain a high-purity semi-esterified modified terpolymer resin.

[0036] Step 5: Blending and Preparation:

[0037] High-purity semi-esterified modified ternary copolymer resin, epoxy resin, photoinitiator, photocrosslinking monomer, functional filler, and additives are mixed, dispersed at high speed and / or milled with three rollers to a fineness ≤10μm, and degassed under vacuum to obtain high-purity SMA copolymer blend material for circuit boards.

[0038] Furthermore, in step one, the organic solvent is selected from at least one of propylene glycol methyl ether acetate, butanone, cyclohexanone, N,N-dimethylformamide, and N-methylpyrrolidone; the free radical initiator is selected from at least one of azobisisobutyronitrile, benzoyl peroxide, and di-tert-butyl peroxide, and the amount of initiator is 0.5-5% of the total mass of the monomer.

[0039] Furthermore, in step two, the polymerization inhibitor is hydroquinone, and the amount used is 0.05-0.5% of the mass of (meth)acrylate hydroxy ester; the esterification catalyst is selected from triethylamine and N,N-dimethylbenzylamine.

[0040] Furthermore, in step three, the volume ratio of the deionized water / methanol mixed precipitant is 1:2 to 2:1.

[0041] Furthermore, in step four, the solid content of the resin organic solution is 30%, and the column flow rate is 2 BV / h.

[0042] This invention provides a high-purity SMA copolymer blend material for circuit boards and its preparation method, which has the following beneficial effects:

[0043] (1) High heat resistance: By introducing rigid imide rings into the copolymer backbone through N-substituted maleimide monomers such as NPMI / FPMI, the intrinsic Tg of the ternary copolymer resin can be significantly increased from 100-150℃ for ordinary SMA binary copolymers to 160-240℃, meeting the high temperature requirements of lead-free soldering and multilayer pressing.

[0044] (2) Electronic grade high purity: Through precipitation purification combined with mixed bed ion exchange refining process, the total metal ion content is controlled to ≤10ppm and the chloride ion content is ≤5ppm, which is far superior to conventional industrial grade SMA resin (metal ions are usually >100ppm), fundamentally inhibiting the failure of CAF and ECM of PCB under humid and hot electric field.

[0045] (3) Multifunctional integrated design: The main chain of the terpolymer itself contains anhydride groups (for epoxy thermocuring), acrylate double bonds (for UV curing) and carboxyl groups (for dilute alkaline solution development) introduced through semi-esterification, realizing the three-in-one function of "photocuring + thermocuring + alkaline development".

[0046] (4) Multi-scenario adaptability: By adjusting the ratio of ternary copolymer monomers, the degree of esterification and the blending formulation, the same resin platform can be adapted to circuit inks, chemical inks, solder resist inks and pore-filling resins respectively, significantly reducing the variety of resins for different product lines.

[0047] (5) Narrow molecular weight distribution: PDI is controlled below 1.8 by semi-continuous dripping and mixing with chain transfer agent.

[0048] (6) Low dielectric properties: When FPMI is selected as the third monomer, the Dk of the cured product can be reduced to 2.8-3.2 (@10GHz) and the Df can be reduced to 0.005-0.010 (@10GHz). Detailed Implementation

[0049] This invention proposes a high-purity SMA copolymer blend material for circuit boards, which is prepared by blending a semi-esterified modified ternary copolymer resin, an epoxy resin, a photoinitiator, a photocrosslinking monomer, a functional filler, additives, and an organic solvent.

[0050] By weight, the proportions of each blend component are as follows: 100 parts of semi-esterified modified terpolymer resin, 10-50 parts of epoxy resin, 1-10 parts of photoinitiator, 5-30 parts of photocrosslinking monomer, 5-80 parts of functional filler, 0.1-5 parts of additives, and the amount of organic solvent required to adjust the viscosity of the system.

[0051] The semi-esterified modified ternary copolymer resin is first obtained by controlled free radical polymerization of styrene, maleic anhydride and N-substituted maleimide functional monomers to obtain a ternary copolymer matrix resin, which is then semi-esterified by (meth)acrylate hydroxy ester, and then purified by precipitation and ion exchange.

[0052] The monomer composition for preparing the terpolymer matrix resin, by molar percentage, is: 35-70 mol% styrene, 20-50 mol% maleic anhydride, and 5-30 mol% N-substituted maleimide functional monomers.

[0053] Furthermore, the N-substituted maleimide functional monomers are selected from one or more of N-phenylmaleimide, N-(4-fluorophenyl)maleimide, N-(4-hydroxyphenyl)maleimide, and N-cyclohexylmaleimide.

[0054] Furthermore, the semi-esterification modification involves ring-opening esterification of 10-70 mol% of anhydride groups in the terpolymer matrix resin with (meth)acrylate hydroxy esters.

[0055] Furthermore, the (meth)acrylate hydroxy ester is selected from one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and pentaerythritol triacrylate.

[0056] Furthermore, the epoxy resin is selected from at least one of bisphenol A type epoxy, bisphenol F type epoxy, phenolic epoxy, o-cresol phenolic epoxy, and triglycidyl isocyanurate.

[0057] Furthermore, the functional filler is selected from at least one of silica, barium sulfate, alumina, boron nitride, and talc.

[0058] Furthermore, the additive is selected from at least one of defoamers, leveling agents, dispersants, and thixotropic agents.

[0059] A method for preparing a high-purity SMA copolymer blend for circuit boards includes the following steps:

[0060] Step 1: Ternary copolymerization:

[0061] Under an inert atmosphere, styrene, maleic anhydride, and N-substituted maleimide functional monomers are dissolved in an organic solvent, and a free radical initiator is added. Solution polymerization is then carried out at 60-120°C for 2-12 hours to obtain a terpolymer matrix resin solution. The organic solvent is selected from at least one of propylene glycol methyl ether acetate, butanone, cyclohexanone, N,N-dimethylformamide, and N-methylpyrrolidone. The free radical initiator is selected from at least one of azobisisobutyronitrile, benzoyl peroxide, and di-tert-butyl peroxide, and the amount of initiator is 0.5-5% of the total monomer mass.

[0062] Step 2, Semi-esterification Modification:

[0063] Hydroxyl methacrylate, a polymerization inhibitor, and an esterification catalyst were added to a terpolymer matrix resin solution and reacted at 60-100℃ for 2-8 hours. The esterification rate was controlled by monitoring the attenuation of the characteristic peak of the acid anhydride using infrared spectroscopy to obtain a semi-esterified modified resin solution. The polymerization inhibitor was hydroquinone, and the amount used was 0.05-0.5% of the mass of the hydroxy methacrylate. The esterification catalyst was selected from triethylamine and N,N-dimethylbenzylamine.

[0064] Step 3: Precipitation and purification:

[0065] The semi-esterified modified resin solution was added dropwise to a deionized water / methanol mixed precipitant to precipitate the solid. After filtration and washing, the solid was dried under vacuum at 40-60℃. The volume ratio of the deionized water / methanol mixed precipitant was 1:2 to 2:1.

[0066] Step 4: Ion exchange purification:

[0067] The dried solid was redissolved in an organic solvent and passed through a mixed-bed ion exchange column filled with H⁺ type strong acid cation exchange resin and OH⁻ type strong base anion exchange resin. The effluent was collected and the solvent was removed to obtain a high-purity semi-esterified modified ternary copolymer resin. The solid content of the resin organic solution was 30%, and the column flow rate was 2 BV / h.

[0068] Step 5: Blending and Preparation:

[0069] High-purity semi-esterified modified ternary copolymer resin, epoxy resin, photoinitiator, photocrosslinking monomer, functional filler, and additives are mixed, dispersed at high speed and / or milled with three rollers to a fineness ≤10μm, and degassed under vacuum to obtain high-purity SMA copolymer blend material for circuit boards.

[0070] Synthesis Examples (1-5)

[0071] Synthesis Examples 1-5 were used to prepare the high-purity semi-esterified modified ternary copolymer resin of the present invention, which is the core matrix intermediate of the high-purity SMA copolymer blend material for circuit boards of the present invention;

[0072] In particular, Synthesis Examples 1-3 completed the synthesis of styrene-maleic anhydride-N-substituted maleimide terpolymer matrix resin, Synthesis Example 4 completed the semi-esterification modification of the terpolymer, and Synthesis Example 5 completed precipitation purification and ion exchange purification to obtain a high-purity modified resin intermediate that meets the requirements of total metal ions ≤10ppm and chloride ions ≤5ppm, as detailed below:

[0073] Example 1: Preparation of St / MA / NPMI ternary copolymer matrix resin R1

[0074] A 500mL four-necked reaction flask was equipped with a mechanical stirrer, a reflux condenser, a nitrogen delivery tube, and a constant-pressure dropping funnel. 19.9g (0.115mol) of NPMI, 8.2g (0.288mol) of MA, and 120mL of PGMEA were added. Nitrogen gas was introduced and the mixture was stirred to dissolve the monomers, and the temperature was raised to 80℃. 6.0g (0.346mol) of St3, 2.1g (2.5% of total monomer mass) of AIBN, and 1.7g (2.0% of total monomer mass) of the chain transfer agent n-dodecyl mercaptan were dissolved in 60mL of PGMEA and added dropwise to the reaction flask at a constant-pressure dropping funnel over 2 hours. After the addition was complete, the reaction was maintained at 80℃ for 4 hours, then the temperature was raised to 100℃ and the reaction continued for 2 hours. The mixture was cooled to room temperature to obtain a light yellow, viscous terpolymer solution.

[0075] Product specifications: Mn=5200g / mol, PDI=1.42, acid value 195mgKOH / g, Tg=198℃ as measured by DSC; monomer molar ratio St:MA:NPMI=46:38:16.

[0076] Example 2: Preparation of St / MA / FPMI ternary copolymer matrix resin R2

[0077] The equipment and operating procedures are the same as in Example 1; NPMI is replaced with FPMI, i.e., 22.0g (0.115mol) of N-(4-fluorophenyl)maleimide; the other raw materials and process conditions remain unchanged.

[0078] Product specifications: Mn=4800g / mol, PDI=1.48, acid value 205mgKOH / g, Tg=186℃; Dk=2.61, Df=0.008 under 10GHz conditions.

[0079] Example 3: Preparation of St / MA / CHMI ternary copolymer matrix resin R3

[0080] The equipment process is the same as in Example 1; NPMI is replaced with CHMI, i.e., 20.6g (0.115mol) of N-cyclohexylmaleimide; the initiator is replaced with 2.5g of BPO; the polymerization temperature is 90-110℃, and the rest remains unchanged.

[0081] Product specifications: Mn=5800g / mol, PDI=1.55, acid value 210mgKOH / g, Tg=172℃.

[0082] Example 4: Preparation of semi-esterified modified resins MR1, MR2, and MR3

[0083] Take 100g of solid resin from each of the terpolymer solutions from Examples 1-3; add 13.5g of HEA, corresponding to an anhydride molar esterification rate of approximately 50%; add 0.03g of hydroquinone as a polymerization inhibitor; add 0.5g of triethylamine as a catalyst; react at 80℃ for 4 hours; monitor with FTIR at 1780 cm⁻¹. -1 1850cm -1 The characteristic peaks of the acid anhydride decreased by about 50%, yielding semi-esterified modified resins MR1 ​​(derived from R1), MR2 (derived from R2), and MR3 (derived from R3).

[0084] MR1: Acid value 108 mg KOH / g, double bond equivalent 480 g / eq, Tg = 175℃;

[0085] MR2: Acid value 112 mg KOH / g, double bond equivalent 475 g / eq, Tg = 165℃; 10 GHz: Dk = 2.72, Df = 0.009;

[0086] MR3: Acid value 116 mg KOH / g, double bond equivalent 470 g / eq, Tg = 158℃.

[0087] Example 5: High-purity preparation of H-MR1, H-MR2, and H-MR3

[0088] Take MR1 resin solution and slowly add a 1:1 volume ratio of deionized water / methanol mixed precipitant, with the precipitant volume being 8 times the resin solution volume; stir vigorously to precipitate resin solids; filter under vacuum, wash the filter cake three times with deionized water; dry under vacuum at 50℃ for 12 h. Dissolve the dried resin solids in PGMEA to prepare a 30% solids solution; pass it through a mixed bed of H⁺ type Amberlyst 15 cation exchange resin and Amberlyst A26OH⁻ type anion exchange resin at a flow rate of 2 BV / h; collect the effluent and desolventize under reduced pressure to obtain high-purity resin H-MR1.

[0089] ICP-MS detection of H-MR1: Na + =1.2ppm, K + =0.8ppm, Ca2+ =2.1ppm, Fe 2+ =1.5ppm, Cu 2+ =0.3ppm, Zn 2+ =0.2ppm, Ni 2+ =0.1ppm; total metal ions 6.2ppm, chloride ions 2.5ppm.

[0090] MR2 and MR3 were processed using the same refining process, yielding H-MR2 with a total metal content of 5.8 ppm and H-MR3 with a total metal content of 7.1 ppm, respectively.

[0091] Application Examples (AD):

[0092] Application Example AD uses 100 parts by weight of the high-purity semi-esterified modified ternary copolymer resin obtained in the above synthesis examples as the matrix, and further blends it with epoxy resin, photoinitiator, photocrosslinking monomer / diluent, functional filler, additives, and organic solvent to obtain the high-purity SMA copolymer blend material for circuit boards as defined in this invention. These materials correspond to solder resist ink, photosensitive circuit ink, via-filling resin, and electroplating resistant selective ink products, and provide processing technology and integrity performance test data for the finished products. Based on the processes disclosed in Synthesis Examples 1-5, a core matrix resin conforming to the parameter limitations can be prepared. Combined with the formulation and preparation operation of Application Example AD, the complete technical solution of the copolymer blend material of this invention can be reproduced, as follows:

[0093] Application Example A: Solder Resist Ink Composition

[0094]

[0095] Preparation process: All components are dispersed and premixed at high speed, then ground with three rollers to a fineness of ≤8μm, and vacuum degassing is performed to obtain green solder resist ink.

[0096] Processing technology: Screen printing on FR-4 copper-clad laminate; pre-baking at 80℃ for 30 minutes; UV exposure at 365nm, 500mJ / cm 2 ; 1% sodium carbonate aqueous solution, alkaline development at 30℃ for 60s; then curing at 150℃ for 60min.

[0097] Application Example B: Photosensitive Circuit Ink Composition

[0098]

[0099] Processing steps: screen printing; pre-baking at 75℃ for 20 minutes; UV exposure at 400mJ / cm²; alkaline development, followed by acid etching to evaluate resolution.

[0100] Application Example C: Pore-sealing Resin Composition

[0101]

[0102] Processing technology: vacuum plugging, curing at 150℃ for 60 minutes; testing curing shrinkage rate, CTE, and void ratio.

[0103] Application Example D: Electroplating-resistant chemical ink composition

[0104]

[0105] Processing steps: screen printing, pre-baking, UV exposure, alkaline development; H2SO4 4- CuSO4 acid copper plating at 2A / dm² for 60 min was used to evaluate electroplating resistance and adhesion.

[0106] Comparative examples (1-3):

[0107] Comparative Example 1: Ordinary binary SMA solder resist ink, commercial SMA1000 resin St / MA=1:1, Mn=5500, Tg=155℃ replaced H-MR1, and the remaining components were consistent with Application Example A.

[0108] Comparative Example 2: No ion exchange purification was performed; MR1 was used directly instead of H-MR1, with a total metal ion concentration of approximately 85 ppm; the remaining components were the same as in Application Example A.

[0109] Comparative Example 3: The through-hole solder resist ink was prepared according to Example 1 of Patent CN121718212A.

[0110] Performance test results:

[0111] Comparison of solder resist ink performance:

[0112]

[0113] Properties of circuit inks, chemically selected inks, and via-filling resins:

[0114]

[0115] Test results show that the SMA copolymer blend material of this invention is significantly superior to traditional binary SMA and existing patented solutions in key indicators such as glass transition temperature, adhesion, hardness, heat resistance to welding, damp heat insulation reliability, CAF resistance, dielectric properties, development resolution, electroplating resistance, curing shrinkage, and pore filling void rate.

Claims

1. A high-purity SMA copolymer blend material for circuit boards, characterized in that, The copolymer blend is prepared by blending semi-esterified modified ternary copolymer resin, epoxy resin, photoinitiator, photocrosslinking monomer, functional filler, additives and organic solvent; By weight, the proportions of each blend component are as follows: 100 parts of semi-esterified modified terpolymer resin, 10-50 parts of epoxy resin, 1-10 parts of photoinitiator, 5-30 parts of photocrosslinking monomer, 5-80 parts of functional filler, 0.1-5 parts of additives, and the amount of organic solvent required to adjust the viscosity of the system. The semi-esterified modified ternary copolymer resin is first obtained by controlled free radical polymerization of styrene, maleic anhydride and N-substituted maleimide functional monomers to obtain a ternary copolymer matrix resin, which is then semi-esterified by (meth)acrylate hydroxy ester, and then subjected to precipitation purification and ion exchange post-treatment. The monomer composition of the terpolymer matrix resin prepared by molar percentage is: 35-70 mol% styrene, 20-50 mol% maleic anhydride, and 5-30 mol% N-substituted maleimide functional monomers.

2. The high-purity SMA copolymer blend material for circuit boards according to claim 1, characterized in that, The N-substituted maleimide functional monomers are selected from one or more of N-phenylmaleimide, N-(4-fluorophenyl)maleimide, N-(4-hydroxyphenyl)maleimide, and N-cyclohexylmaleimide.

3. The high-purity SMA copolymer blend material for circuit boards according to claim 1, characterized in that, The semi-esterification modification involves ring-opening esterification of 10-70 mol% of anhydride groups in the terpolymer matrix resin with (meth)acrylate hydroxy ester.

4. The high-purity SMA copolymer blend material for circuit boards according to claim 1, characterized in that, The (meth)acrylate hydroxy ester is selected from one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and pentaerythritol triacrylate.

5. The high-purity SMA copolymer blend material for circuit boards according to claim 1, characterized in that, The epoxy resin is selected from at least one of bisphenol A epoxy, bisphenol F epoxy, phenolic epoxy, o-cresol phenolic epoxy, and triglycidyl isocyanurate.

6. The high-purity SMA copolymer blend material for circuit boards according to claim 1, characterized in that, The functional filler is selected from at least one of silicon dioxide, barium sulfate, aluminum oxide, boron nitride, and talc.

7. The high-purity SMA copolymer blend material for circuit boards according to claim 1, characterized in that, The additive is selected from at least one of defoamers, leveling agents, dispersants, and thixotropic agents.

8. The method for preparing a high-purity SMA copolymer blend for circuit boards as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Ternary copolymerization: Under an inert atmosphere, styrene, maleic anhydride, and N-substituted maleimide functional monomers are dissolved in an organic solvent, a free radical initiator is added, and solution polymerization is carried out at 60-120℃ for 2-12 hours to obtain a terpolymer matrix resin solution. Step 2, Semi-esterification Modification: (Meth)acrylate hydroxy ester, polymerization inhibitor and esterification catalyst were added to the terpolymer matrix resin solution and reacted at 60-100℃ for 2-8h. The esterification rate was controlled by monitoring the degree of weakening of the characteristic peak of the acid anhydride by infrared spectroscopy, and a semi-esterified modified resin solution was obtained. Step 3: Precipitation and purification: The semi-esterified modified resin solution was added dropwise to a deionized water / methanol mixed precipitant to precipitate the solid. After filtration and washing, the solid was dried under vacuum at 40-60℃. The volume ratio of the deionized water / methanol mixed precipitant was 1:2 to 2:

1. Step 4: Ion exchange purification: The dried solid is redissolved in an organic solvent, and then filled with H... + Type I strong acid cation exchange resin and OH - A mixed-bed ion exchange column of a strong base anion exchange resin was used to collect the effluent and remove the solvent to obtain a high-purity semi-esterified modified ternary copolymer resin; the solid content of the resin organic solution was 30%, and the column flow rate was 2 BV / h. Step 5: Blending and Preparation: High-purity semi-esterified modified ternary copolymer resin, epoxy resin, photoinitiator, photocrosslinking monomer, functional filler, and additives are mixed, dispersed at high speed and / or milled with three rollers to a fineness ≤10μm, and degassed under vacuum to obtain high-purity SMA copolymer blend material for circuit boards.

9. The method for preparing a high-purity SMA copolymer blend for circuit boards according to claim 8, characterized in that, In step one, the organic solvent is selected from at least one of propylene glycol methyl ether acetate, butanone, cyclohexanone, N,N-dimethylformamide, and N-methylpyrrolidone; the free radical initiator is selected from at least one of azobisisobutyronitrile, benzoyl peroxide, and di-tert-butyl peroxide, and the amount of initiator is 0.5-5% of the total mass of the monomer.

10. The method for preparing a high-purity SMA copolymer blend for circuit boards according to claim 8, characterized in that, In step two, the polymerization inhibitor is hydroquinone, and the amount used is 0.05-0.5% of the mass of (meth)acrylate hydroxy ester; the esterification catalyst is selected from triethylamine and N,N-dimethylbenzylamine.

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