Photocurable composition

Abstract

The present invention generally provides a composition having improved heat aging resistance, crack resistance, and solder compatibility, wherein the resin composition comprises: (a) an epoxy resin comprising a compound having two or more epoxy groups per molecule, (b) a binder comprising a compound having at least one carboxyl group per molecule, (c) a photopolymerization initiator, and (d) a filler composition comprising silica, talc, and wollastonite.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of international patent application serial number PCT / CN2020 / 097364 filed on June 22, 2020, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates generally to photocurable compositions, and more particularly to photocurable compositions for use in solder masks. Background Art

[0004] Compositions containing epoxy resins and fillers are known in the art for solder mask applications. However, such compositions available in the art have less than desirable heat aging resistance, crack resistance, and solder compatibility.

[0005] For example, US6342547 discloses epoxy compositions using fused silica or wollastonite as fillers, but examples using fused silica show poor crack resistance performance.

[0006] US8999433 discloses an epoxy composition using both fused silica and wollastonite as fillers, but the amount of filler used in the composition is much higher than the intended amount, which may result in poor solvent resistance.

[0007] Thus, there is a need for a photocurable composition having improved heat aging resistance, crack resistance, and solder compatibility compared to currently available photocurable compositions. Summary of the invention

[0008] It has now been unexpectedly discovered that the compositions and methods of the present invention solve the above problems. Advantages of the presently disclosed photocurable compositions include: (1) improved heat aging resistance, (2) improved crack resistance, and / or (3) improved flux compatibility compared to current compositions.

[0009] The present invention relates to photocurable compositions having improved crack resistance compared to the prior art and methods for preparing these compositions. In one embodiment, the present invention provides a photocurable composition comprising: (a) an epoxy resin comprising a compound having two or more epoxy groups per molecule, (b) a binder comprising a compound having at least one carboxyl group per molecule, (c) a photopolymerization initiator, and (d) a filler composition comprising silica, talc, and wollastonite.

[0010] In another embodiment, the present invention provides a method of making an insulating layer by coating a substrate with a photocurable composition and then curing the photocurable composition.

[0011] In yet another embodiment, the present invention provides an insulating layer comprising a substrate coated with the photocurable composition of the present invention. DETAILED DESCRIPTION

[0012] If it appears in this document, the term "includes / comprising" and its derivatives are not intended to exclude the presence of any additional components, steps or procedures, whether or not the above are disclosed herein. For the avoidance of any doubt, all compositions claimed herein by use of the term "includes / comprising" may include any additional additives or compounds unless otherwise specified. In contrast, if it appears in this document, the term "consisting essentially of excludes any other components, steps or procedures from the scope of any adjacent description, except those that are not necessary for operability; and if used, the term "consisting of" excludes any components, steps or procedures that are not explicitly depicted or listed. Unless otherwise specified, the term "or" refers to the listed members individually and in any combination.

[0013] The articles "a" and "an" are used herein to refer to one or more than one (ie, at least one) of the grammatical objects of the article. By way of example, "a resin" means one resin or more than one resin.

[0014] The phrases "in one embodiment," "according to one embodiment," and the like generally mean that the particular feature, structure, or characteristic following the phrase is included in at least one embodiment of the present invention, and may be included in more than one embodiment of the present invention. Importantly, such phrases do not necessarily refer to the same embodiment.

[0015] If the specification states that a component or feature "may / might" be included or have a property, that particular component or feature is not required to be included or have that property.

[0016] The present invention generally provides a photocurable composition comprising: (a) an epoxy resin comprising a compound having two or more epoxy groups per molecule, (b) a binder comprising a compound having at least one carboxyl group per molecule, (c) a photopolymerization initiator, and (d) a filler composition comprising silica, talc and wollastonite.

[0017] Epoxy resins suitable as component (a) are those commonly used in epoxy resin technology. Non-limiting examples of epoxy resins are:

[0018] I) Polyglycidyl ether or poly(β-methylglycidyl) ether, obtainable by reacting a compound having at least two free alcoholic and / or phenolic hydroxyl groups with epichlorohydrin or β-methylepichlorohydrin under alkaline conditions or in the presence of an acid catalyst, followed by alkaline treatment.

[0019] Glycidyl ethers of this type are derived, for example, from acyclic alcohols, such as ethylene glycol, diethylene glycol or higher polyethylene glycols, propane-1,2-diol or polypropylene glycol, propane-1,3-diol, butane-1,4-diol, polyoxytetramethylene glycol, pentane-1,5-diol, hexane-1,6-diol, hexane-2,4,6-triol, glycerol, 1,1,1-trimethylol-propane, pentaerythritol, sorbitol and polyepichlorohydrin.

[0020] Other glycidyl ethers of this type are derived from cycloaliphatic alcohols, such as 1,4-cyclohexanedimethanol, bis(4-hydroxycyclohexyl)methane or 2,2-bis(4-hydroxycyclohexyl)propane, or from alcohols containing aromatic groups and / or other functional groups, such as N,N-bis(2-hydroxyethyl)aniline or p,p'-bis(2-hydroxyethylamino)diphenylmethane. Glycidyl ethers can also be based on mononuclear phenols, such as resorcinol or hydroquinone, or on polynuclear phenols, such as bis(4-hydroxyphenyl)methane, 4,4'-dihydroxybiphenyl, bis(4-hydroxyphenyl)sulfone, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane or 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane.

[0021] Other hydroxy compounds suitable for preparing glycidyl ethers are novolacs obtainable by condensation of aldehydes, such as formaldehyde, acetaldehyde, chloral or furfural, with phenols or bisphenols which are unsubstituted or substituted by chlorine atoms or C1-C9-alkyl groups, for example phenol, 4-chlorophenol, 2-methylphenol or 4-tert-butylphenol.

[0022] II) biphenyl epoxy resin (e.g., YX4000 manufactured by Mitsubishi Chemical Corporation), biphenyl novolac epoxy resin (e.g., NC-3000 manufactured by Nippon Kayaku Co. Ltd.), biphenyl ether epoxy resin (e.g., YSLV-80XY manufactured by Nippon Steel & Sumikin Chemical Co. Ltd.), special difunctional epoxy resin (e.g., YSLV-120TE manufactured by Nippon Steel & Sumikin Chemical Co. Ltd.), dicyclopentadiene epoxy resin (e.g., EPICLON HP-7200H manufactured by DIC Corporation), naphthalene epoxy resin (e.g., EPICLON HP-4032, EPICLON HP-4700, EPICLON HP-4770 manufactured by DIC Corporation).

[0023] III) Polyglycidyl ethers or poly(β-methylglycidyl) ethers, obtainable by reacting a compound having at least two free alcoholic and / or phenolic hydroxyl groups with epichlorohydrin or β-methylepichlorohydrin under alkaline conditions or in the presence of an acid catalyst, followed by alkaline treatment.

[0024] Glycidyl ethers of this type are derived, for example, from acyclic alcohols, such as ethylene glycol, diethylene glycol or higher polyethylene glycols, propane-1,2-diol or polypropylene glycol, propane-1,3-diol, butane-1,4-diol, polyoxytetramethylene glycol, pentane-1,5-diol, hexane-1,6-diol, hexane-2,4,6-triol, glycerol, 1,1,1-trimethylol-propane, pentaerythritol, sorbitol and polyepichlorohydrin.

[0025] Other glycidyl ethers of this type are derived from cycloaliphatic alcohols, such as 1,4-cyclohexanedimethanol, bis(4-hydroxycyclohexyl)methane or 2,2-bis(4-hydroxycyclohexyl)propane, or from alcohols containing aromatic groups and / or other functional groups, such as N,N-bis(2-hydroxyethyl)aniline or p,p'-bis(2-hydroxyethylamino)diphenylmethane. Glycidyl ethers can also be based on mononuclear phenols, such as resorcinol or hydroquinone, or on polynuclear phenols, such as bis(4-hydroxyphenyl)methane, 4,4'-dihydroxybiphenyl, bis(4-hydroxyphenyl)sulfone, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane or 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane.

[0026] Other hydroxy compounds suitable for preparing glycidyl ethers are novolacs obtainable by condensation of aldehydes, such as formaldehyde, acetaldehyde, chloral or furfural, with phenols or bisphenols which are unsubstituted or substituted by chlorine atoms or C1-C9-alkyl groups, for example phenol, 4-chlorophenol, 2-methylphenol or 4-tert-butylphenol.

[0027] IV) Poly(N-glycidyl) compounds obtainable by dehydrochlorination of the reaction products of epichlorohydrin with amines containing at least two amine hydrogen atoms. Such amines are, for example, aniline, n-butylamine, bis(4-aminophenyl)methane, m-xylylenediamine or bis(4-methylaminophenyl)methane.

[0028] However, poly(N-glycidyl) compounds also include triglycidyl isocyanurate, N,N′-diglycidyl derivatives of cyclic alkylene ureas, such as ethylene urea or 1,3-propylene urea, and diglycidyl derivatives of hydantoins, such as 5,5-dimethylhydantoin.

[0029] V) Cycloaliphatic epoxy resins, for example bis(2,3-epoxycyclopentyl)ether, 2,3-epoxycyclopentyl glycidyl ether, 1,2-bis(2,3-epoxycyclopentyloxy)ethane or 3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexanecarboxylate.

[0030] However, it is also possible to use epoxy resins in which the 1,2-epoxy group is bonded to different heteroatoms or functional groups, such compounds including, for example, N,N,O-triglycidyl derivatives of 4-aminophenol, glycidyl ethers / esters of salicylic acid, N-glycidyl-N′-(2-glycidyloxypropyl)-5,5-dimethylhydantoin and 2-glycidyloxy-1,3-bis(5,5-dimethyl-1-glycidylhydantoin-3-yl)propane.

[0031] In the context of the present invention, the term "cycloaliphatic epoxy resin" denotes any epoxy resin having cycloaliphatic structural units, ie it includes both cycloaliphatic glycidyl compounds and β-methylglycidyl compounds and epoxy resins based on cyclooxides.

[0032] Suitable cycloaliphatic glycidyl and β-methylglycidyl compounds are the glycidyl and β-methylglycidyl esters of cycloaliphatic polycarboxylic acids such as tetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, hexahydrophthalic acid, 3-methylhexahydrophthalic acid and 4-methylhexahydrophthalic acid.

[0033] Other suitable cycloaliphatic epoxy resins are the diglycidyl and β-methylglycidyl ethers of cycloaliphatic alcohols such as 1,2-, 1,3- and 1,4-dihydroxycyclohexane, 1,4-cyclohexanedimethanol, 1,1-bis(hydroxymethyl)cyclohex-3-ene, bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hydroxycyclohexyl)propane and bis(4-hydroxycyclohexyl)sulfone.

[0034] Examples of the epoxy resin having an epoxycycloalkane structure are bis(2,3-epoxycyclopentyl)ether, 2,3-epoxycyclopentyl glycidyl ether, 1,2-bis(2,3-epoxycyclopentyl)ethane, vinylcyclohexene dioxide, 3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3',4'-epoxy-6'-methylcyclohexanecarboxylate, bis(3,4-epoxycyclohexylmethyl)adipate and bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate.

[0035] Preferred cycloaliphatic epoxy resins are bis(4-hydroxycyclohexyl)methane diglycidyl ether, 2,2-bis(4-hydroxycyclohexyl)propane diglycidyl ether, diglycidyl tetrahydrophthalate, diglycidyl 4-methyltetrahydrophthalate, diglycidyl 4-methylhexahydrophthalate, 3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexanecarboxylate and especially diglycidyl hexahydrophthalate.

[0036] Aliphatic epoxy resins can also be used as the epoxy resin of component (a). Aliphatic epoxy resins include, for example, but not limited to, epoxidized products of unsaturated fatty acid esters. If epoxidized products of unsaturated fatty acid esters are used as the epoxy resin of component (a), preferably, epoxy-containing compounds derived from mono- and poly-fatty acids having 12 to 22 carbon atoms and an iodine value of 30 to 400 are used, such as laureic acid, myristic acid, palmitoleic acid, oleic acid, gadoleic acid, erucic acid, ricinoleic acid, linoleic acid, linolenic acid, elaidic acid, octadecatriene-4-keto acid, arachidonic acid, and docosapentaenoic acid.

[0037] Non-limiting examples of epoxidation products of suitable unsaturated fatty acid esters for component (a) are epoxidation products of soybean oil, linseed oil, perilla oil, tung oil, oti oil, safflower oil, poppy seed oil, hemp oil, cottonseed oil, sunflower oil, rapeseed oil, polyunsaturated triglycerides, triglycerides from Euphorbia, peanut oil, olive oil, olive kernel oil, almond oil, kapok oil, hazelnut oil, apricot kernel oil, beech nut oil, lupine oil, corn oil, sesame oil, grape seed oil, Raman oil, castor oil, herring oil, sardine oil, menhaden oil, whale oil, tall oil and derivatives thereof.

[0038] Also suitable as epoxy resins are the higher unsaturated derivatives which are obtainable by subsequent dehydrogenation of those oils.

[0039] The olefinic double bonds of the unsaturated fatty acid groups of the above compounds can be epoxidized according to known methods, for example by reaction with hydrogen peroxide, alkyl hydroperoxides or peracids (for example performic acid or peracetic acid), optionally in the presence of a catalyst. Within the scope of the present invention, both fully epoxidized oils and partially epoxidized derivatives which still contain free double bonds can be used for component (a).

[0040] Preference is given to using epoxidized soybean oil and epoxidized linseed oil.

[0041] Mixtures of the epoxy resins I) to V) mentioned above can also be used. The photocurable composition according to the invention preferably comprises as component (a) an aromatic or cycloaliphatic glycidyl ether or glycidyl ester which is liquid or solid at 25° C., preferably a diglycidyl ether or diglycidyl ester of bisphenol A or bisphenol F. Preferred epoxy resins can also be obtained by reacting polyglycidyl ethers and polyglycidyl esters with alcohols such as diols. The reaction with diols increases the molecular weight.

[0042] A particularly preferred epoxy resin is the glycidyl ether of bisphenol A reacted with a less than equimolar amount of bisphenol A.

[0043] According to a preferred embodiment, the photocurable composition comprises a material selected from the group consisting of polyglycidyl esters, poly(β-methylglycidyl) esters, polyglycidyl ethers, poly(β-methylglycidyl) ethers and mixtures thereof.

[0044] According to one embodiment, 40 to 80 wt % of the epoxy resin includes a biphenyl type epoxy resin having an epoxy equivalent of 150 to 450 g / mol.

[0045] According to another embodiment, 20 to 40 wt % of the epoxy resin comprises a bisphenol A type epoxy resin having an epoxy equivalent weight of 175 to 210 g / mol.

[0046] According to one embodiment, the epoxy resin is present in the photocurable composition in an amount of about 5 wt % to about 30 wt %, or preferably about 5 wt % to about 15 wt %, based on the total weight of the photocurable composition.

[0047] In one embodiment, the binder comprising a compound having at least one carboxyl group per molecule (i.e., component (b)) comprises (i) one or more of a cresol novolac resin or an aromatic epoxy resin and (ii) one or more of a carboxyl-functional polyester resin, a carboxyl-functional acrylic resin, or a glycidyl-functional acrylic resin.

[0048] The carboxyl functional acrylic resin and the glycidyl functional acrylic resin include alkyl (meth)acrylates. Non-limiting examples of alkyl (meth)acrylates include methyl acrylate, methyl methacrylate, ethyl acrylate, acrylic acid, methacrylic acid, butyl acrylate, and butyl methacrylate.

[0049] The weight average molecular weight (Mw) of the binder is 1,000 to 80,000 Daltons, preferably 2,000 to 40,000 Daltons.

[0050] Molecular weight (MW) is the weight average molecular weight defined by gel permeation chromatography (GPC) using polystyrene as a reference.

[0051] In another embodiment, component (b) (i.e., a binder comprising a compound having at least one carboxyl group per molecule) is obtained by reacting a cresol novolac-type epoxy compound and an unsaturated monocarboxylic acid with a saturated or unsaturated polyacid anhydride. Unreacted saturated or unsaturated polyacid anhydride is subsequently reacted with a hydroxyl-containing monomer to remove the saturated or unsaturated polyacid anhydride.

[0052] In yet another embodiment, component (b) is obtained by reacting bisphenol A epoxy acrylate with a diisocyanate. The diisocyanate can be any commonly available diisocyanate, such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), methylene diisocyanate (MDI), methylene dicyclohexyl isocyanate, trimethyl hexamethylene diisocyanate, hexane diisocyanate, hexamethylamine diisocyanate, methylene dicyclohexyl isocyanate, toluene diisocyanate, 1,2-diphenylethane diisocyanate, 1,3-diphenylpropane diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethyl diisocyanate, etc. Preferably, the diisocyanate is an aliphatic diisocyanate, such as HDI, for maximum flexibility of the oligomer. At this time, the molecule has a diisocyanate functional group.

[0053] According to one embodiment, the binder including a compound having at least one carboxyl group per molecule is present in the photocurable composition in an amount of about 10 wt % to about 60 wt %, preferably about 30 wt % to about 50 wt %, based on the total weight of the photocurable composition.

[0054] In one embodiment, the binder comprising a compound having at least one carboxyl group per molecule has an acid value greater than or equal to 40 mg KOH / g. Preferably, the binder comprising a compound having at least one carboxyl group per molecule has an acid value greater than or equal to 60 mg KOH / g. In addition, the binder comprising a compound having at least one carboxyl group per molecule preferably has an acid value less than or equal to 120 mg KOH / g, or more preferably less than or equal to 100 mg KOH / g.

[0055] In another embodiment, the photopolymerization initiator of the present invention is a free radical photoinitiator. Typical representatives of free radical photoinitiators are: benzoins, such as benzoin; benzoin ethers, such as benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether, benzoin phenyl ether and benzoin acetate; acetophenones, such as acetophenone, 2,2-dimethoxyacetophenone and 1,1-dichloroacetophenone; benzil, benzil ketal, such as benzil dimethyl ketal and benzil diethyl ketal; anthraquinones, such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone and 2-amylanthraquinone; and triphenylphosphine; benzoylphosphine oxides, for example 2,4,6-trimethylbenzoyl-diphenylphosphine oxide ( TPO); bisacylphosphine oxides; benzophenones such as benzophenone and 4,4'-bis(N,N'-dimethylamino)benzophenone; thioxanthones and xanthone; acridine derivatives; phenazine derivatives, quinoxaline derivatives or 1-phenyl-1,2-propanedione 2-O-benzoyl oxime; 1-aminophenyl ketone or 1-hydroxyphenyl ketone such as 1-hydroxycyclohexylphenyl ketone, phenyl 1-hydroxyisopropyl ketone and 4-isopropylphenyl 1-hydroxyisopropyl ketone.

[0056] Preferably, the free radical photoinitiator is 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-isopropylthioxanthone, or a mixture thereof.

[0057] According to one embodiment, the photopolymerization initiator is present in the photocurable composition in an amount of about 1 wt % to about 10 wt %, preferably about 2 wt % to about 6 wt %, based on the total weight of the photocurable composition.

[0058] An essential component of the photocurable composition according to the present invention is a filler composition comprising silica, talc and wollastonite. The filler composition may optionally further comprise at least one of barium sulfate and kaolin.

[0059] Silicon dioxide is an oxide of silicon and has the chemical formula SiO2.

[0060] According to a preferred embodiment, the silica is amorphous silica. Preferably, the amorphous silica is natural amorphous silica or fused silica.

[0061] According to a preferred embodiment, the amorphous silica has an average particle size (d ) of 1 to 100 μm, more preferably 2 to 50 μm, and most preferably 2 to 10 μm, determined according to ISO 13320-1:1999. 50 ).

[0062] d 50is called the median particle size. This means that the powder contains 50% of the specific 50 Value of particle size larger than 50% of the particle size d 50 The smaller the particle size, the smaller the particle size. 95 This means that 95% of the particles have a ratio of d 95 The particle size is smaller than d 95 Value for greater granularity.

[0063] Preferably, the amorphous silica is surface treated. Preferably, the amorphous silica is surface treated with a silane, more preferably a silane selected from the group consisting of aminosilanes, epoxysilanes, (meth)acrylic silanes, methylsilanes and vinylsilanes.

[0064] Preferred silanes are (meth)acrylic silanes.

[0065] Talc is a clay mineral composed of hydrated magnesium silicate with the chemical formula Mg3Si4O 10 (OH)2. Talc in powder form is widely used as a filler. Talc is commercially available, for example, under the name FH105 from Fuji TALC INDUSTRIAL Co. Ltd.

[0066] Preferably, the talc is surface treated. Preferably, the talc is surface treated with a silane, more preferably a silane selected from the group consisting of aminosilanes, epoxysilanes, (meth)acrylic silanes, methylsilanes and vinylsilanes.

[0067] Preferably the silane is a (meth)acrylic silane.

[0068] The third essential filler component is wollastonite. Wollastonite is a naturally occurring needle-shaped calcium silicate having the formula Ca3[Si3O9] and a particle size in the micrometer range. Artificial wollastonite is also needle-shaped. Wollastonite can be found, for example, under the names From Nyco Corporation or under the name (For example 283-100EST or 283-600EST) was commercially available from Quarzwerke, Germany.

[0069] According to a preferred embodiment, the wollastonite is preferably of an average particle size d of 1 to 100 μm, more preferably 3 to 50 μm and most preferably 2 to 15 μm, determined according to ISO 13320-1:1999. 50 of powder.

[0070] More preferred is wherein the wollastonite has a particle size d of 1 to 200 μm, more preferably 2 to 100 μm and most preferably 3 to 20 μm as determined according to ISO 13320-1:1999.95 A photocurable composition.

[0071] Wollastonite preferably has a carbon content of 0.40 to 0.90 g / cm 3 , more preferably 0.49 to 0.80 g / cm 3 And most preferably 0.55 to 0.76 g / cm 3 Bulk density.

[0072] Particularly preferred are those having a relative humidity of 2 to 5 m, determined according to DIN 66132. 2 / g of BET surface area of ​​wollastonite.

[0073] The photocurable composition according to the present invention preferably comprises surface-treated wollastonite. Preferably, the wollastonite is surface-treated with a silane, which is preferably selected from the group consisting of aminosilanes, epoxysilanes, (meth)acrylic silanes, methylsilanes and vinylsilanes.

[0074] Preferably the silane is a (meth)acrylic silane.

[0075] According to one embodiment, the filler composition is present in the photocurable composition in an amount of about 20 wt % to about 50 wt %, preferably about 30 wt % to about 39 wt %, based on the total weight of the photocurable composition.

[0076] In another embodiment, the photocurable composition may also optionally include an acrylate monomer, a curing agent, a coupling agent, a defoaming agent, a flame retardant, an antioxidant, a solvent, a surfactant, a pigment, a polymerization inhibitor, a stabilizer, or any other typical additives used in epoxy resin materials.

[0077] Advantages of the presently disclosed photocurable compositions include: (1) improved heat aging resistance, (2) improved crack resistance, and / or (3) improved flux compatibility compared to the prior art.

[0078] The present invention also provides a method for forming an insulating layer, which comprises: coating a substrate with a photocurable composition as disclosed herein, pre-drying the coated substrate at about 70°C to 80°C for about 30 to 90 minutes, irradiating the coated substrate with activation energy, thermally curing the coated substrate for a first time at about 20°C to 40°C for about 30 to 120 seconds, dissolving and removing unexposed areas of the coated substrate, and thermally curing the coated substrate for a second time at about 100°C to 200°C for about 30 to 120 minutes.

[0079] Furthermore, the present invention provides an insulation layer produced by the method described herein.

[0080] The following examples should be considered as illustrative of the invention and not limiting in any way.

[0081] raw material

[0082] Solvent 1: diethylene glycol ethyl acetate (supplier: Polynt, UK);

[0083] Solvent 2: PMA, propylene glycol monomethyl ether acetate (supplier: Dow Chemical Company, USA);

[0084] Adhesive 1: PR-3000, carboxyl-containing modified cresol novolac epoxy acrylate (supplier: Shanghai ShowaDenka highpolymer Cop.);

[0085] Binder 2: UXE-3000, acid-modified epoxy acrylate (supplier: Nippon Kayaku, Japan);

[0086] Binder 3: PACAZ-250, acid-modified acrylate copolymer (supplier: Daicel Corporation, Japan);

[0087] Photoinitiator 1: 369, 2-benzyl-2-(dimethylamino)-1-[4-(morpholinyl)phenyl]-1-butanone (supplier: IGM);

[0088] Photoinitiator 2: IHT-PI TPO, diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide (supplier: Insight High Technology);

[0089] Photoinitiator 3: IHT-PI ITX, 2-isopropylthioxanthone (supplier: Insight High Technology);

[0090] Photoinitiator 4: OXE02, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone 1-(O-acetyloxime) (supplier: BASF, Germany);

[0091] Photoinitiator 5: JMT-784, bis(η5-2,4-cyclopentadien-1-yl)bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titanium (supplier: Yueyang Kimoutain Sci-tech);

[0092] Acrylate monomer 1: SR444NS, pentaerythritol triacrylate (supplier: Sartomer);

[0093] Acrylate Monomer 2: DPCA-60, ethoxylated dipentaerythritol hexaacrylate (supplier: Nippon Kayaku, Japan);

[0094] Acrylate Monomer 3: 2308, tris(2-hydroxyethyl)isocyanurate triacrylate (supplier: Eternal);

[0095] Curing agent 1: 1-cyanoguanidine (supplier: Alzchem Trostberg, Germany);

[0096] Curing agent 2: UR300Fenuron (supplier: Alzchem Trostberg, Germany);

[0097] Curing agent 3: 2,4,6-triamino-1,3,5-triazine (supplier: Sichuan Yunong Chemical);

[0098] Epoxy resin 1: NC-3000 biphenyl phenolic varnish epoxy resin (supplier: Nippon Kayaku, Japan);

[0099] Epoxy resin 2: jER YX-4000k, 2,2'-((3,3',5,5'-tetramethyl-(1,1'-biphenyl)-4,4'-diyl)-bis(oxymethylene))-bis(ethylene oxide) (supplier: Mitsubishi Chemical Corporation, Japan);

[0100] Epoxy Resin 3: GY 2600, bisphenol A epoxy resin (supplier: Huntsman Advanced Materials, Switzerland);

[0101] Pigment 1: Pigment Yellow 147 (supplier: BASF, Germany);

[0102] Pigment 2: Pigment Blue 15:4 (supplier: ChemFine International);

[0103] Coupling agent: A-174, γ-methacryloxypropyltrimethoxysilane (supplier: Momentive);

[0104] Antioxidants: 1010, pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (supplier: BASF, Germany);

[0105] Polymerization inhibitor: dihydroxy-1,4-benzene (supplier: Rhodia);

[0106] Defoaming agent: KSZ-66 silicone oil (supplier: Shinetsu Silicone);

[0107] Filler 1: MEGASIL TM 525 fused silica (supplier: Sibelco);

[0108] Packing 2: 1363-800EST talc, surface treated with epoxy silane (supplier: Quarzwerke Group);

[0109] Packing 3: 1363-800MST talc, surface treated with acrylate silane (supplier: Quarzwerke Group);

[0110] Packing 4: 283-600EST wollastonite, surface treated with epoxy silane (supplier: Quarzwerke Group);

[0111] Packing 5: 283-600MST wollastonite, surface treated with acrylate silane (supplier: Quarzwerke Group);

[0112] Filler 6: barium sulfate B34 (supplier: Sakai Chemical);

[0113] Packing 7: 102A kaolin (supplier: Imerys).

[0114] Embodiment 1-15:

[0115] The components of Examples 1 to 15 are shown in Table 1. All values ​​listed in Table 1 refer to parts by weight of the photocurable composition. As shown in Table 1, Examples 8 to 15 are comparative examples containing filler compositions not from the present invention.

[0116] Table 1

[0117]

[0118]

[0119] program

[0120] Examples 1-15 were prepared by combining the components and mixing at room temperature until the mixture was uniform and grinding with a three-roll mill. A 50 μm thick glass fiber epoxy copper-clad laminate including copper foil was prepared. A core material was obtained by etching a designed pattern on the epoxy copper-clad laminate. The surface of the obtained core material was completely coated with a photocurable composition by screen printing, and then heated and dried at 75°C for 40 minutes to obtain a coating with a thickness of 25 μm. A negative mask was placed directly on the coating, and the negative mask was irradiated with ultraviolet rays using an exposure device equipped with a metal halide lamp, and the coating was thus exposed to 400 mJ / cm 2 The coating was selectively exposed to light with an exposure amount of . Then, the negative mask was removed from the coating, and the coating was developed with a 1.0% sodium carbonate aqueous solution at a temperature of about 28-32° C. for 90 s, so that a portion of the coating cured by exposure to light remained on the printed circuit board as a solder mask layer. The solder mask layer was further heated at 150° C. for 60 minutes and thermally cured. Thus, a test piece including a solder mask layer was obtained.

[0121] result

[0122] Physical properties

[0123]

[0124] 1) Tested according to IPC-TM-650 2.4.27.2, pencil hardness; target ≥5H

[0125] 2) Tested according to IPC-TM-650 2.3.42; Target: No blistering or discoloration

[0126] 3) Tested according to IPC-TM-650 2.4.6; Target: No peeling

[0127] 4) Tested according to ISO 2409; target GT0 or GT1

[0128] 5) The board for evaluation is placed in a cold-hot chamber with an operating temperature cycle between -40°C and 160°C for crack resistance testing. Each cycle is performed for 30 minutes, and there is a 10-second break between each cycle. The appearance of the board is observed with a 100× magnifier after 1000 cycles and 2000 cycles. The crack rate of the cracked angle in all corners of the board is calculated. The crack resistance test is also called a thermal cycle test (TCT) and is performed according to methods known in the art (see, for example, patent application US2012125672).

[0129] P = Test passed

[0130] Table 2 shows the physical properties of Examples 1-15. For Examples 1 to 7, the compositions have improved heat aging resistance, crack resistance, and flux compatibility. However, when the amount of the filler composition is too high (Example 7), there is an impact on the solvent resistance performance. The composition using the filler treated with acrylate silane has better crack resistance than the composition using the filler treated with epoxy silane (Example 5). The composition using only one filler (Examples 8-12) or the composition using two fillers (Examples 13-15) has poor solvent resistance or crack resistance, which cannot meet the requirements for solder mask applications.

Claims

1. A photocurable composition comprising: (a) an epoxy resin comprising a compound having two or more epoxy groups per molecule, (b) a binder comprising a compound having at least one carboxyl group per molecule, (c) a photopolymerization initiator, and (d) A filler composition comprising silica, talc and wollastonite. 2 . The photocurable composition according to claim 1 , wherein the epoxy resin comprises a biphenyl type epoxy resin having an epoxy equivalent of 150 to 450 g / mol. 3 . The photocurable composition according to claim 2 , wherein 40 to 80 wt % of the epoxy resin comprises a biphenyl type epoxy resin having an epoxy equivalent of 150 to 450 g / mol. 4 . The photocurable composition according to claim 1 , wherein the epoxy resin comprises a bisphenol A type epoxy resin having an epoxy equivalent of 175 to 210 g / mol. 5 . The photocurable composition according to claim 1 , wherein 20 to 40 wt % of the epoxy resin comprises a bisphenol A type epoxy resin having an epoxy equivalent of 175 to 210 g / mol.

6. The photocurable composition according to any one of claims 1 to 3, wherein the epoxy resin is present in the photocurable composition in an amount of 5 wt% to 30 wt% based on the total weight of the photocurable composition.

7. The photocurable composition according to any one of claims 1 to 3, wherein the epoxy resin is present in the photocurable composition in an amount of 5 wt% to 15 wt% based on the total weight of the photocurable composition.

8. The photocurable composition according to any one of claims 1 to 3, wherein the binder comprising a compound having at least one carboxyl group per molecule is present in the photocurable composition in an amount of 10 wt % to 60 wt % based on the total weight of the photocurable composition.

9. The photocurable composition according to any one of claims 1 to 3, wherein the binder comprising a compound having at least one carboxyl group per molecule is present in the photocurable composition in an amount of 30 wt % to 50 wt % based on the total weight of the photocurable composition. 10 . The photocurable composition according to claim 1 , wherein the photopolymerization initiator is present in the photocurable composition in an amount of 1 wt % to 10 wt % based on the total weight of the photocurable composition. 11 . The photocurable composition according to claim 1 , wherein the photopolymerization initiator is present in the photocurable composition in an amount of 3 wt % to 5 wt % based on the total weight of the photocurable composition.

12. The photocurable composition according to any one of claims 1 to 3, wherein the silicon dioxide is amorphous silicon dioxide.

13. The photocurable composition of any one of claims 1 to 3, wherein the filler composition is present in the photocurable composition in an amount of 20 wt% to 50 wt%, based on the total weight of the photocurable composition.

14. The photocurable composition of any one of claims 1 to 3, wherein the filler composition is present in the photocurable composition in an amount of 30 wt% to 38 wt%, based on the total weight of the photocurable composition.

15. A method for forming an insulating layer, the method comprising: Coating a substrate with the photocurable composition according to any one of claims 1 to 14; pre-drying the coated substrate at 70° C. to 80° C. for 30 to 90 minutes; irradiating the coated substrate with activation energy; thermally curing the coated substrate for a first time at 20° C. to 40° C. for 30 to 120 seconds; dissolving and removing unexposed areas of the coated substrate; and thermally curing the coated substrate for a second time at 100° C. to 200° C. for 30 to 120 minutes.

16. Insulation layer produced by the method according to claim 15.

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