TWI716593B - Method of forming hardened coating - Google Patents

Abstract

The subject of the present invention is to provide the formation of a hardened coating film that can fill the through holes or blind holes sufficiently even if the through holes or blind holes are provided on the substrate and make the thickness of the coating film uniform method.

The solution of the present invention is a method for forming a hardened coating film, which is characterized in that it has the following steps: by ink-jet method, the viscosity of the substrate at 25°C is 120~3300mPa. s step of the first photosensitive resin composition, the step of forming a first cured coating film from the first photosensitive resin composition applied as described above by the first curing treatment, coating on the first cured coating film The step of applying the second photosensitive resin composition and the step of forming a second cured coating film from the second photosensitive resin composition applied above by the second curing treatment.

Description

Method of forming hardened coating

The present invention relates to a method for forming a cured coating film by ejecting a photosensitive resin composition onto a substrate using an inkjet method to form a coating film.

Conventionally, the substrate, for example, when forming an insulating coating with a desired circuit pattern on a printed wiring board, a photosensitive resin composition is coated by a screen printing method and then preliminarily dried to have a circuit pattern. A film with a translucent pattern other than the pad is closely adhered to the coating film of the photosensitive resin composition, and active energy rays are irradiated from above to remove the non-exposed area corresponding to the pad with a dilute alkali aqueous solution to make the coating film It is developed and post-cured (Patent Document 1).

However, blind holes are sometimes provided on the printed wiring board. In this case, if the screen printing method is used, the blind holes cannot be fully filled, and there is a problem that the photosensitive resin composition applied on the periphery of the blind holes may move away.

In addition, if a blind hole is provided on the printed wiring board, the blind hole cannot be sufficiently filled with the photosensitive resin composition, and the photosensitive resin composition applied on the periphery of the blind hole may move away, which may cause formation For printing The thickness of the cured coating film of the wire board becomes a problem of unevenness.

In addition, when a through hole is provided on the printed wiring board, if the screen printing method is used, the coated photosensitive resin composition will leak to the back side of the printed wiring board through the through hole, making it impossible to bury the through hole In addition, the photosensitive resin composition applied on the periphery of the through hole will move away. Therefore, depending on the use conditions of the substrate, etc., it is also required to prevent such a problem.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2002-293882 A

In view of the above situation, the object of the present invention is to provide a method for forming a hardened coating film that can fill the through holes or blind holes sufficiently even if a through hole or a blind hole is provided on a substrate, and uniformize the thickness of the coating film.

The aspect of the present invention is a method for forming a hardened coating film, which is characterized in that it has the following steps: by ink-jet method, coating the substrate with a viscosity of 120~3300mPa at 25°C. The step of the first photosensitive resin composition of s is based on the first photosensitive resin composition applied above, and the first The step of curing treatment to form the first cured coating film, the step of coating the second photosensitive resin composition on the first cured coating film, and the second photosensitive resin composition applied by the aforementioned The step of curing to form a second cured coating film.

In the above aspect, the first photosensitive resin composition applied by the inkjet method is subjected to a first curing treatment to form a first cured coating film, and the first cured coating film is further included with inkjet The second photosensitive resin composition is applied by a desired coating method of the method, and the second curing treatment is performed on the first cured coating film and the applied second photosensitive resin composition.

The aspect of the present invention is a method for forming a cured coating film, wherein the coating method of the second photosensitive resin composition is screen printing method, inkjet method, roll coating method, bar coating method, spraying method , Curtain coating method, doctor blade method, smear method, doctor blade coating method, knife coating method or gravure coating method.

The aspect of the present invention is a method for forming a cured coating film, wherein the second photosensitive resin composition is coated on the first cured coating film by a coating method other than the inkjet method.

The aspect of the present invention is a method for forming a hardened coating film, wherein the aforementioned other coating methods are screen printing, roll coating, bar coating, spray coating, curtain coating, and doctor blade method , Smear method, knife coating method, knife coating method or gravure coating method.

The aspect of the present invention is a method of forming a hardened coating film, wherein the viscosity of the first photosensitive resin composition at 25°C is 200 to 1000 mPa. s.

The aspect of the present invention is a method for forming a hardened coating film, wherein the viscosity of the second photosensitive resin composition at 25°C is 120 to 60,000 mPa. s.

The aspect of the present invention is a method for forming a cured coating film, wherein the first photosensitive resin composition is the same composition as the second photosensitive resin composition.

The aspect of the present invention is a method for forming a cured coating film, wherein the first photosensitive resin composition is applied to the through holes and/or blind holes of the substrate.

The aspect of the present invention is a method for forming a hardened coating film, wherein the first hardening treatment is exposure treatment or heat treatment by active energy rays.

The aspect of the present invention is a method for forming a hardened coating film, wherein the exposure amount of the exposure treatment by the active energy rays is 30 to 500 mJ/cm ² .

The aspect of the present invention is a method for forming a cured coating film, wherein the second curing treatment is exposure treatment or heat treatment performed by active energy rays.

According to aspects of the present invention, before coating the photosensitive resin composition by the desired coating method, first, the viscosity at 25°C is coated by inkjet method to 120~3300mPa. s's first photosensitive resin composition to form a first cured coating film, thereby even if it is provided on the substrate to be coated By placing through holes or blind holes, the through holes or blind holes can be fully filled, and the photosensitive resin composition coated on the periphery of the through holes or blind holes can be prevented from moving away. Furthermore, sufficient filling of the through holes or blind holes not only prevents the photosensitive resin composition from moving, but also prevents the first photosensitive resin composition from being coated in a convex shape, so that the coating film can be cured The thickness is uniform.

According to the aspect of the present invention, the viscosity at 25°C of the first photosensitive resin composition is 200~1000mPa. s, and can fill through holes or blind holes reliably, and make the thickness of the hardened coating film more uniform.

According to the aspect of the present invention, the exposure amount by the exposure process with the active energy line is 30~500mJ/cm ² , and the exposure time is shortened, and not only blind holes but also via holes can be filled more reliably. Therefore, it is possible to more reliably prevent the photosensitive resin composition applied on the periphery of the through hole from moving away while improving productivity.

1.‧‧The first photosensitive resin composition

2‧‧‧The second photosensitive resin composition

3‧‧‧Substrate

4‧‧‧Jet distributor

5‧‧‧The first hardening treatment

11‧‧‧The first hardened coating

12‧‧‧Second Hardening Film

[Figure 1] Figure (a) is an explanatory diagram of coating by the inkjet method in the method of forming a cured coating film of the embodiment of the present invention, and Figure (b) is of the embodiment of the present invention The explanatory diagram of the first curing treatment in the forming method of the hardened coating film is the same as the diagram (c) is an explanatory diagram of the hardened coating film obtained by the method of forming the hardened coating film of the embodiment of the present invention.

[Figure 2] is an explanatory diagram of the method of evaluating the uniformity of the coating film of the example.

Next, embodiments of the method for forming a cured coating film of the present invention will be described with reference to the drawings. The method of forming a hardened coating film of the present invention is applicable even to a substrate provided with a blind hole, but here, it is applied to a substrate provided with a through hole (for example, a circuit of a printed wiring board or a flexible printed wiring board). The case where a cured coating film is formed on the substrate) will be described as an example.

As shown in Fig. 1(a), in the method of forming a cured coating film according to the embodiment of the present invention, first, by the inkjet method (in Fig. 1, the spray dispenser 4 is used) Ink method as an example), a specific amount of the first photosensitive resin composition 1 is applied on the substrate 3. In Fig. 1, a through hole 31 is provided in the substrate 3, and the first photosensitive resin composition 1 is applied to the through hole 31 part.

The viscosity of the first photosensitive resin composition 1 at 25°C is adjusted to 120~3300mPa with a thinner. s. The lower limit of the viscosity at 25°C is 120mPa. s, and when the first photosensitive resin composition 1 is applied to the through hole 31 by the inkjet method, it can prevent the first photosensitive resin composition 1 from leaking to the back of the substrate 3 through the through hole 31 during coating. On the other hand, even the through hole 31 can be filled with the first photosensitive resin composition 1. In addition, the upper limit of the viscosity at 25°C is 3300mPa. s. When the first photosensitive resin composition 1 is applied by the inkjet method, the first photosensitive resin composition 1 can be prevented from being coated in a convex shape, and even the thickness of the cured coating film can be made uniform.

The viscosity of the first photosensitive resin composition 1 at 25°C It is 120~3300mPa. The range of s is not particularly limited, but in terms of filling the through holes 31 more reliably, the lower limit is preferably 200 mPa. s, 250mPa is particularly preferred. s. Furthermore, in terms of making the thickness of the cured coating film more uniform, the upper limit of the viscosity at 25°C is preferably 1000 mPa. s, more preferably 800mPa. s, 600mPa is particularly preferred. s. In addition, the size of the through hole 31 is not particularly limited. For example, the inner diameter is 50 to 200 μm and the depth is 50 to 200 μm.

Next, as shown in 1st (b), the 1st hardening process 5 is performed with respect to the applied 1st photosensitive resin composition, and the 1st hardening coating film 11 is formed. Examples of the first curing treatment 5 series include: exposure treatment using active energy rays, heat treatment using a heating device, and the like.

The conditions for the exposure treatment using active energy rays are not particularly limited as long as the first photosensitive resin composition 1 undergoes photocuring. For example, through holes or blind holes are filled more reliably and As far as the thickness of the cured coating film is more uniform, the lower limit of exposure to ultraviolet light (for example, wavelength 240~420nm) is preferably 10mJ/cm ² , so that the through hole can be filled more reliably. , More preferably 25mJ/cm ² , particularly preferably 30mJ/cm ² . On the other hand, the upper limit of the exposure dose of ultraviolet rays is not particularly limited in terms of the point of photocuring, but in terms of shortening the exposure time and improving productivity, it is preferably 2000 mJ/cm ² , especially Preferably, it is 500mJ/cm ² . Although there are no particular limitations on the light source of ultraviolet rays, examples thereof include metal halide lamps, ultra-high pressure mercury lamps, xenon lamps, UV-LEDs, and the like. In addition, the heat treatment conditions are not particularly limited as long as the first photosensitive resin composition 1 is thermally cured, and examples thereof include 60 to 170° C., 15 to 80 minutes, and the like.

Next, as shown in FIG. 1(c), the second photosensitive resin composition 2 is coated on the obtained first cured coating film 11 by a desired coating method. In FIG. 1(c), the second photosensitive resin composition 2 is applied to the entire surface of the substrate 3. Although the time interval from the end of the first curing treatment 5 to the start of the application of the second photosensitive resin composition 2 is not particularly limited, it prevents oxidation on the surface of the substrate 3 or the surface of the first cured coating film 11 In particular, it is preferably 72 hours or less.

The coating method of the second photosensitive resin composition 2 is not particularly limited, and well-known methods used in the past can be used. Examples include screen printing methods and inkjet methods (for example, using a jet dispenser). Inkjet method, etc.), roll coating method, bar coating method, spray coating method, curtain coating method, doctor blade method, smear method, knife coating method, knife coating method, gravure coating method, etc. The coating method of the second photosensitive resin composition 2 may be the same as the coating method of the first photosensitive resin composition 1 (that is, the inkjet method), or may be coating other than the inkjet method. Cloth method. Among them, the screen printing method is preferred in terms of ease of coating the entire substrate.

The second photosensitive resin composition 2 may be the same composition as the first photosensitive resin composition 1, or may be a different composition. In addition, the viscosity of the second photosensitive resin composition 2 at 25°C may be the same as or different from the viscosity of the first photosensitive resin composition 1 at 25°C. Although the viscosity of the second photosensitive resin composition at 25°C varies depending on the coating method used, for example, the lower limit is preferably 120 mPa in terms of coating to a specific film thickness. s, using screen printing as the coating method In the case of 10000mPa, it is more preferable for the point to be applied to a specific film thickness. s, particularly preferably 12000mPa. s. Also, for example, in terms of coatability, the upper limit of the viscosity at 25°C is preferably 60000mPa. s, in the case of using screen printing as the coating method, it is more preferably 50000mPa. s, as far as the leveling point is concerned, it is particularly preferably 30000mPa. s.

The film thickness when the second photosensitive resin composition 2 is applied can be appropriately selected in accordance with the use condition of the substrate. For example, when applied to a circuit substrate, 10 to 100 μm can be cited.

Next, a second curing treatment is performed on the applied second photosensitive resin composition 2 to form a second cured coating film 12. The second hardening treatment system is the same as the first hardening treatment 5, and examples thereof include exposure treatment using active energy rays, heat treatment using a heating device, and the like. In addition, as the treatment conditions of the second hardening treatment, the same treatment conditions as those of the first hardening treatment 5 can be cited. Moreover, in terms of productivity and the like, the first curing treatment 5 series can have a smaller exposure amount than the second curing treatment, and can have a lower heating temperature and a shorter heating time than the second curing treatment.

By performing the second curing treatment, the second cured coating film 12 composed of the second photosensitive resin composition 2 can be formed on the entire substrate surface.

In addition, when the second photosensitive resin composition 2 contains an organic solvent, after the second photosensitive resin composition 2 is applied, in order to volatilize the organic solvent and become a non-sticky coating film, it may be After preliminary drying by a dryer or the like, the second curing treatment is performed. As the pre-drying conditions, for example, 15~60 at a temperature of 60~80℃ The heating time is about minutes. In addition, when the coating film of the second photosensitive resin composition 2 is developed, the second curing treatment (performed after preliminary drying) is preferably an exposure treatment. In this case, the exposure process is to closely adhere a film with a pattern that has a light-transmitting pattern other than the circuit pattern pad on the coating film of the second photosensitive resin composition 2, and irradiate active energy rays from above. Then, the coating film of the second photosensitive resin composition 2 is photocured.

After the second photosensitive resin composition 2 is cured by light, the non-exposed area corresponding to the aforementioned pad is removed with a dilute alkali aqueous solution to develop the coating film. The above-mentioned development method can be used, for example, a spray method, a shower method, etc., although the diluted alkali aqueous solution used is not particularly limited, for example, 0.5 to 5 mass% sodium carbonate aqueous solution can be mentioned. After development, it is cured with a hot air circulating dryer at 130 to 170° C. for 20 to 80 minutes, thereby forming a target cured film on the substrate 3.

Next, the first photosensitive resin composition and the second photosensitive resin composition (hereinafter, the first photosensitive resin composition and the second photosensitive resin composition may be collectively referred to as "photosensitive resin composition"). Description.

Examples of the cured film system of the photosensitive resin composition include insulating films such as solder resist films formed on circuit boards such as printed wiring boards.

Examples of the aforementioned photosensitive resin composition system include: a photosensitive resin composition containing a carboxyl group-containing photosensitive resin, a photopolymerization initiator, a urethane (meth)acrylate, an epoxy compound, and a diluent Things.

Carboxyl-containing photosensitive resin

The carboxyl group-containing photosensitive resin is not particularly limited, and examples include resins having one or more photosensitive unsaturated double bonds. Examples of the carboxyl group-containing photosensitive resin system include radically polymerizable unsaturated monocarboxylic acids such as acrylic acid or methacrylic acid (hereinafter, sometimes referred to as "(meth)acrylic acid"), which have a compound in one molecule At least a part of the epoxy groups of the polyfunctional epoxy resin having two or more epoxy groups react to obtain radically polymerizable unsaturated monocarboxylated epoxy resins such as epoxy (meth)acrylate, and Polyacid denatured radical polymerizable unsaturated monocarboxylated epoxy resin such as polyacid denatured epoxy (meth)acrylate obtained by reacting an acid or its anhydride with the generated hydroxyl group.

Any one of the aforementioned polyfunctional epoxy resins can be used as long as it is a bifunctional or higher epoxy resin. Although the epoxy equivalent of the multifunctional epoxy resin is not particularly limited, it is preferably 1000 or less, and particularly preferably 100 to 500. Examples of polyfunctional epoxy resins include rubber-modified epoxy resins such as biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, and silicone modified epoxy resins. , Ε-caprolactone modified epoxy resin, bisphenol A type, bisphenol F type, bisphenol AD type and other phenol novolac type epoxy resin, o-cresol novolak type and other cresol novolac type ring Oxygen resin, bisphenol A novolac type epoxy resin, cycloaliphatic multifunctional epoxy resin, glycidyl ester type multifunctional epoxy resin, glycidylamine type multifunctional epoxy resin, heterocyclic multifunctional epoxy resin Resins, bisphenol modified novolac type epoxy resins, multifunctional modified novolac type epoxy resins, phenols Condensate type epoxy resin with aromatic aldehyde having phenolic hydroxyl group. In addition, it is also possible to use halogen atoms such as Br and Cl introduced into these resins. These epoxy resins can be used alone, or two or more of them can be mixed and used.

The radically polymerizable unsaturated monocarboxylic acid is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, crotonic acid, and cinnamic acid, and acrylic acid and methacrylic acid are preferred. These radically polymerizable unsaturated monocarboxylic acids may be used alone, or two or more of them may be mixed and used.

The reaction method of the epoxy resin and the radical polymerizable unsaturated monocarboxylic acid is not particularly limited. For example, the epoxy resin and the radical polymerizable unsaturated monocarboxylic acid can be heated in a suitable diluent. Its response.

The polybasic acid or polybasic acid anhydride is used to react with the hydroxyl group generated by the reaction of the aforementioned epoxy resin and the radically polymerizable unsaturated monocarboxylic acid to introduce free carboxyl groups into the resin. The polybasic acid or its anhydride is not particularly limited, and either saturated or unsaturated can be used. Examples of polybasic acids include succinic acid, maleic acid, adipic acid, citric acid, phthalic acid, tetrahydrophthalic acid, 3-methyltetrahydrophthalic acid, 4-methyltetrahydro Phthalic acid, 3-ethyltetrahydrophthalic acid, 4-ethyltetrahydrophthalic acid, hexahydrophthalic acid, 3-methylhexahydrophthalic acid, 4-methylhexahydrophthalic acid Hydrophthalic acid, 3-ethylhexahydrophthalic acid, 4-ethylhexahydrophthalic acid, methyltetrahydrophthalic acid, methylhexahydrophthalic acid, bridged methylene Tetrahydrophthalic acid, methyl bridged methylene tetrahydrophthalic acid, trimellitic acid, pyromellitic acid and diglycolic acid, etc. Examples of the basic acid anhydride series include these anhydrides. These compounds can be used alone or in combination of two or more.

The above-mentioned polybasic acid-modified unsaturated monocarboxylic acid epoxy resin can also be used as a carboxylic acid-containing photosensitive resin, but it can also be used as required by having one or more radical polymerizable unsaturated groups and The epoxy glycidyl compound reacts with the carboxyl group of the above-mentioned polybasic acid-denatured unsaturated monocarboxylated epoxy resin to further introduce radical polymerizable unsaturated groups to further improve the sensitivity of the carboxyl-containing photosensitive resin .

The carboxyl group-containing photosensitive resin that enhances the photosensitivity is that by the reaction of the aforementioned glycidyl compound, the radically polymerizable unsaturated group is bonded to the side chain of the polybasic acid modified unsaturated monocarboxylated epoxy resin skeleton Therefore, the photopolymerization reversibility is high, and it can have excellent photosensitive properties. Examples of the compound system having one or more radically polymerizable unsaturated groups and epoxy groups include: glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and neopentyl erythritol triacrylate Monoglycidyl ether and so on. In addition, glycidyl groups may have a plurality in one molecule. The above-mentioned compound system having one or more radically polymerizable unsaturated groups and epoxy groups may be used alone or in combination of two or more kinds.

Photopolymerization initiator

The photopolymerization initiator is not particularly limited as long as the general user is used. Examples include ethyl ketone, 1-[9-ethyl-6-(2-methylbenzyl)-9H-carbazole-3- Base)-1-(0-acetoxime) and other oxime initiators, benzoin, benzoin methyl Ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2 -Phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexylphenyl Ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholine-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy- 2-propyl) ketone, diphenyl ketone, p-phenyl diphenyl ketone, 4,4′-diethylamino diphenyl ketone, dichloro diphenyl ketone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4- Dimethyl thioxanthone, 2,4-diethyl thioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, ethyl P-dimethylaminobenzoate, etc. These systems can be used alone, or two or more of them can be mixed and used.

Although the blending amount of the photopolymerization initiator is not particularly limited, it is preferably 5 to 20 parts by mass relative to 100 parts by mass of the carboxyl group-containing photosensitive resin.

Urethane (meth)acrylate

The urethane (meth)acrylate system is helpful for obtaining a flexible hardened coating film. The urethane (meth)acrylate is a urethane (meth)acrylate obtained by reacting (meth)acrylic acid as a radically polymerizable unsaturated monocarboxylic acid with a urethane ) Acrylate is sufficient, and it is not limited to a specific compound. The urethane is obtained by reacting a compound having two or more isocyanate groups in one molecule with a polyol compound having two or more hydroxyl groups in one molecule.

Although there are no particular limitations on the compound having two or more isocyanate groups in one molecule, examples include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and methylene diisocyanate (MDI). ), methylene biscyclohexyl isocyanate, trimethyl hexamethyl diisocyanate, hexane diisocyanate, hexamethylamine diisocyanate, methylene biscyclohexyl isocyanate, toluene diisocyanate, 1,2-diphenyl ethane Diisocyanate, 1,3-diphenylpropane diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethyl diisocyanate and other diisocyanates. These compounds can be used alone or in combination of two or more.

The polyol compound having two or more hydroxyl groups in one molecule is not particularly limited, but examples thereof include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, and 1,3-butanediol Alcohol, 1,2-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, neopentyl glycol, 1,6-hexanediol, 2,2-diethyl-1,3-propanediol, 3,3-dimethylolheptane, 2-ethyl-2-butyl-1,3-propanediol, 1 , C ₂ -C ₂₂ alkane diols such as 12-dodecanediol, 1,18-octadecanediol, or 2-butene-1,4-diol, 2,6-dimethyl- Aliphatic diols such as 1-octene-3,8-diol and other enediols; alicyclic diols such as 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol; glycerin , 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentane, 1,2,6-hexanetriol, trimethylolethane, Trimethylolpropane, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-(hydroxymethyl)pentane, 2,2-bis(hydroxymethyl) Aliphatic triols such as -3-butanol; polyols with more than 4 hydroxyl groups such as tetramethylolmethane, pentaerythritol, dipentaerythritol, and xylitol. These compounds can be used alone or in combination of two or more.

Although the blending amount of urethane (meth)acrylate is not particularly limited, the lower limit is preferably 5 in terms of improving flexibility with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin. Parts by mass, particularly preferably 10 parts by mass. On the other hand, in terms of photosensitivity, the upper limit is preferably 50 parts by mass.

Epoxy compound

The epoxy compound is used to increase the crosslinking density of the cured coating film to obtain a cured coating film with sufficient strength, for example, epoxy resin is added. Examples of epoxy resins include bisphenol A epoxy resins, novolac epoxy resins (phenol novolac epoxy resins, o-cresol novolac epoxy resins, p-tert-butyl phenol Novolac type, etc.), bisphenol F type or bisphenol S type epoxy resin obtained by reacting epichlorohydrin with bisphenol F or bisphenol S, further having cyclohexane oxide group, tricyclodecane oxidation Cycloalicyclic epoxy resins such as compound base, cyclopentene oxide base, etc., ginseng (2,3-epoxypropyl) isocyanurate, triglycidyl ginseng (2-hydroxyethyl) isocyanurate Triglycidyl isocyanurate with triazine ring, dicyclopentadiene type epoxy resin, adamantane type epoxy resin such as acid ester. These compounds can be used alone or in combination of two or more.

Although the blending amount of the epoxy compound is not particularly limited, it is preferably 10-50 parts by mass relative to 100 parts by mass of the carboxyl-containing photosensitive resin in terms of obtaining a coating film with sufficient strength after curing. Preferably it is 20-40 mass parts.

Thinner

The thinner is used to adjust the viscosity or dryness of the photosensitive resin composition. Examples of the diluent include organic solvents that are non-reactive diluents. Examples of organic solvent systems include ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, alcohols such as methanol, isopropanol, and cyclohexanol, and cyclohexane. , Methylcyclohexane and other alicyclic hydrocarbons, petroleum ether, naphtha and other petroleum-based solvents, siloxu, butyl siloxu, carbitol, butyl card Carbitols such as carbitol, ethyl acetate, butyl acetate, cyrus acetate, butyl cyrus acetate, carbitol acetate, butyl carbitol acetate, ethyl acetate Diethylene glycol acetate, diethylene glycol monoethyl ether acetate and other esters. These systems can be used alone, or two or more of them can be mixed and used.

Moreover, in the photosensitive resin composition, colorants, extender pigments, various additives, defoamers, flame retardants, etc. may be blended as needed.

Next, other embodiments of the method for forming the cured coating film of the present invention will be described. In the above-mentioned embodiment of the method for forming a hardened coating film of the present invention, although a substrate provided with through holes is used, it may be replaced by a substrate provided with blind holes, or may be a substrate not provided with through holes or blind holes. Substrate. It is also applicable to substrates provided with through holes and blind holes. Furthermore, in the method for forming a cured coating film of the present invention, the coating area is not particularly limited. For example, the first cured coating film applied by the inkjet method can be formed on the entire surface of the substrate or on a specific area of the substrate. Comprehensive, can also be in the first On the cured coating film, a second cured coating film is formed by a desired coating method including an inkjet method. In addition, if necessary, a cured coating film may be further formed on the second cured coating film.

[Example]

Hereinafter, although the embodiments of the present invention are described, the present invention is not limited to these examples as long as it does not exceed the gist.

Examples 1~4, Comparative Examples 1~3

The components shown in Table 1 below were blended at the blending ratios shown in Table 1 below, and mixed and dispersed using a 3-roller at room temperature to prepare a resin composition. To this resin composition, further add A specific amount of diluent was used to prepare the photosensitive resin compositions used in Examples 1 to 4 and Comparative Examples 1 to 3. Next, the prepared photosensitive resin composition was coated in the following manner to prepare a test piece.

Test piece production steps

Substrate: the first substrate provided with a through hole with an inner diameter of Φ150μm and a depth of 70μm; the second substrate with a blind hole with an inner diameter of Φ100μm and a depth of 70μm

Surface treatment: acid treatment (5 mass% sulfuric acid aqueous solution)

After surface treatment, using a jet dispenser (manufactured by Nordson Advanced Technology, stage main body Quantum Q-6800, dispensing jet valve DJ-9500), the photosensitive resin composition 1 of Examples 1 to 4 and Comparative Examples 2 to 3 Dot by dot, apply to each through hole of the first substrate and each blind hole of the second substrate. Here, use a UV irradiator (manufactured by USHIO Electric Co.) to make ultraviolet rays with a wavelength of 250~450nm (light source: metal Halogen lamp) 250mJ/cm ² exposure (first curing treatment). The exposure time of 250 mJ/cm ² exposure with a metal halide lamp is about 5 seconds. After exposure, the photosensitive resin compositions of Examples 1 to 4 and Comparative Examples 1 to 3 were screen-printed on the entire surface of the first substrate and the second substrate. In addition, the viscosity of the photosensitive resin composition of Examples 1 to 4 and Comparative Examples 1 to 3 during screen printing was adjusted to 15000 mPa. s.

DRY film thickness for screen printing: 20~23μm

Preliminary drying: 80°C, 20 minutes

Exposure (second hardening treatment): wavelength 250~450nm (light source: metal halide lamp), 250mJ/cm ² (manufactured by Oak Corporation, "HMW-680GW")

Development: 1% by mass sodium carbonate aqueous solution, 60 seconds, spray pressure 0.2MPa

Post-curing: 150°C, 30 minutes

In addition, the DRY film thickness of the screen printing was measured at the part where the coating by the jet dispenser was not performed. In addition, in Comparative Example 1, coating by a jet dispenser was not performed, but only screen printing was performed.

Evaluation

(1) Viscosity (mPa.s)

Using a Brookfield B-type viscometer, the temperature of the photosensitive resin composition of Examples 1 to 4 and Comparative Examples 1 to 3 was 25° C., and the viscosity at 50 rpm was measured.

(2) Through hole filling

For 100 parts of the through holes of the test piece, observe whether the photosensitive resin compositions of Examples 1 to 4 and Comparative Examples 1 to 3 are filled and filled with a microscope (×40 times), and measure the filled through holes The number of departments.

○: 100 parts

△: 99~80 parts

×: Less than 79 parts

(3) Blind hole filling

For 100 blind holes of the test piece, observe whether the photosensitive resin composition of Examples 1 to 4 and Comparative Examples 1 to 3 are filled and buried with a microscope (×40 times), and measure the buried blind holes The number of departments.

○: 100 parts

×: Less than 99 parts

(4) Film uniformity

The cross section of the through hole and the blind hole of the test piece was observed, and the film thickness of the coating portion of the jet distributor was measured. By measuring the part a shown in Fig. 2 (in Fig. 2 only the first substrate is shown as an example), the film thickness of the coating portion of the jet dispenser was measured. Furthermore, the appearance of the coating film of the first substrate and the second substrate was visually evaluated.

○: The film thickness of the coating portion of the jet dispenser is a protrusion of 10 μm or less, and there is no color unevenness.

△: Although the film thickness of the coating portion of the jet dispenser is a protrusion of 10 μm or less, the color is uneven.

×: A protrusion with a film thickness of more than 10 μm in the coating portion of the jet dispenser.

The evaluation results are shown in Table 2.

As shown in Table 2, if the viscosity is 160~1200mPa at 25℃. For the photosensitive resin compositions of Examples 1 to 4 of s, after forming the first cured coating film by the inkjet method, and then forming the second cured coating film by the screen printing method, it is possible to obtain through-hole filling and blinding properties. A hardened coating film with excellent hole filling properties and coating uniformity. Also, according to Examples 2 and 3, if 25°C is used The viscosity is 260~580mPa. The photosensitive resin composition of s improves the filling of via holes and the uniformity of the coating film.

On the other hand, the viscosity at 25°C is 3400mPa. In the photosensitive resin composition of Comparative Example 2 of s, the coating film became convex, and the uniformity of the coating film could not be obtained. Moreover, the viscosity at 25°C is 110mPa. In the photosensitive resin composition of Comparative Example 3 of s, the coated photosensitive resin composition often leaks to the back side of the first substrate through the through holes, and the through hole filling properties cannot be obtained. In addition, according to Comparative Example 1, only the screen printing method can not obtain the through hole filling property and the blind hole filling property.

Examples 5-11, Comparative Example 4

Next, as the UV irradiator used in the first curing treatment, instead of the UV irradiator using a metal halide lamp as the light source, an exposure device (manufactured by USHIO Electric Co., Ltd., model UX-2123SM) using an ultra-high pressure mercury lamp as the light source was used. ), except that the exposure amount of the first hardening treatment is set to 10-100 mJ/cm ² , it is performed in the same manner as in Example 3. That is, in Examples 5 to 11, the photosensitive resin composition of Example 3 was used to form a cured coating film. The wavelength of the ultra-high pressure mercury lamp is set to 365nm, 385nm, 405nm. The exposure time of 30mJ/cm ² exposure with ultra-high pressure mercury lamp is less than 1 second.

The results of the wavelength and exposure of the ultra-high pressure mercury lamp in Examples 5 to 11, the through hole filling property, the blind hole filling property and the coating uniformity as the above evaluation items are shown in the following Table 3. In addition, in Comparative Example 4 in Table 3 below, although the photosensitive resin composition of Example 3 was used, it could not Line 1 hardening treatment.

As shown in Table 3, in Examples 5 to 11 where 10-100mJ/cm ² exposure was carried out with an exposure device using an ultra-high pressure mercury lamp as the light source, any wavelength of 365nm, 385nm, 405nm can be filled with via holes A cured coating film with excellent properties, blind hole filling properties, and coating uniformity. In addition, in Examples 5 to 9 with an exposure amount of 30 to 100 mJ/cm ² , more excellent through hole filling properties can be obtained.

In addition, according to Example 5, the exposure time of 30mJ/cm ² exposure using ultra-high pressure mercury lamp as the light source is less than 1 second due to the excellent through hole filling property, blind hole filling property and coating uniformity. Therefore, the first hardening treatment using the ultra-high pressure mercury lamp as the light source can shorten the time required for exposure compared with the first hardening treatment of Examples 1 to 4 using metal halide lamps, so the productivity is also improved.

On the other hand, the viscosity is 260mPa even at 25℃. In the photosensitive resin composition of Example 3 of s, even in Comparative Example 4 where the first curing treatment (exposure treatment in this embodiment) was not performed, the through-hole filling property could not be obtained.

[Industrial availability]

The method of forming a hardened coating film of the present invention is due to By providing through holes or blind holes on the substrate, the through holes or blind holes can also be fully filled and the thickness of the coating film can be made uniform. Therefore, for example, the utility value is high in the field of the insulating film of the circuit substrate.

1.‧‧The first photosensitive resin composition

2‧‧‧The second photosensitive resin composition

3‧‧‧Substrate

4‧‧‧Jet distributor

5‧‧‧The first hardening treatment

11‧‧‧The first hardened coating

12‧‧‧Second Hardening Film

31‧‧‧Through hole

Claims (10)

A method for forming a hardened coating film, which is characterized by having the following steps: by using an inkjet method using a jet dispenser, coating the substrate with a viscosity of 120~3300mPa at 25°C. s step of the first photosensitive resin composition, the step of forming a first cured coating film from the first photosensitive resin composition applied as described above by the first curing treatment, coating on the first cured coating film The step of applying the second photosensitive resin composition, and the step of forming a second cured coating film from the second photosensitive resin composition applied above by a second curing treatment, wherein the first photosensitive resin composition The substance is coated on the through holes and/or blind holes of the aforementioned substrate. The method for forming a cured coating film according to claim 1, wherein the coating method of the second photosensitive resin composition is screen printing, inkjet, roll coating, bar coating, spray coating, Curtain coating method, doctor blade method, smear method, knife coating method, knife coating method or gravure coating method. The method for forming a cured coating film according to claim 1, which is to coat the second photosensitive resin composition on the first cured coating film by a coating method other than the inkjet method. Such as the method for forming a hardened coating film of claim 3, wherein the aforementioned other coating methods are screen printing method, roll coating method, bar coating method, spraying method, curtain coating method, doctor blade method, Smearing method, doctor blade coating method, knife Coating method or gravure coating method. The method for forming a hardened coating film of claim 1 or 2, wherein the viscosity of the first photosensitive resin composition at 25°C is 200~1000mPa. s. The method for forming a hardened coating film of claim 1 or 2, wherein the viscosity of the second photosensitive resin composition at 25°C is 120 to 60000 mPa. s. The method for forming a cured coating film according to claim 1 or 2, wherein the first photosensitive resin composition is the same composition as the second photosensitive resin composition. The method for forming a cured coating film according to claim 1 or 2, wherein the first curing treatment is exposure treatment or heat treatment performed by active energy rays. The method for forming a hardened coating film according to claim 8, wherein the exposure amount of the exposure treatment with the active energy rays is 30 to 500 mJ/cm ² . The method for forming a cured coating film according to claim 1 or 2, wherein the second curing treatment is exposure treatment or heat treatment performed by active energy rays.

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