JP5190976B2 - Thermosetting resin composition using urethane resin - Google Patents

Description

  The present invention relates to a thermosetting resin composition comprising a polyurethane having two or more carboxyl groups in one molecule and a urethane bond formed by a reaction between a polycarbonate diol and a polyisocyanate, and a thermosetting component. . More specifically, the present invention relates to a thermosetting composition excellent in adhesion to a substrate, low warpage, flexibility, tin plating resistance, moist heat resistance, solder heat resistance, and the like. The thermosetting composition of the present invention can be used for applications in the fields of protective films such as solder resists and interlayer insulating films, electrical insulating materials, ICs and VLSI sealing materials, and laminates.

  The solder resist has a problem of warpage caused by shrinkage due to curing and cooling shrinkage after curing. In addition, as a conventional thermosetting resist, there is an epoxy resin resist composition having an epoxy resin and a dibasic acid anhydride as essential components as disclosed in JP-B-5-75032 (Patent Document 1). However, when it adjusts so that low warpage property and flexibility may be imparted to the coating film to be formed, there is a problem that the tin plating resistance, the moist heat resistance, and the solder heat resistance are lowered.

Japanese Patent Publication No. 5-75032

  Therefore, the present invention provides a thermosetting composition that is excellent in adhesion to a substrate, low warpage, and flexibility, and that is excellent in tin plating resistance, moist heat resistance, and solder heat resistance. Let it be the main issue.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have two or more carboxyl groups in one molecule, and are formed by reaction between polycarbonate diol (a) and polyisocyanate (b). According to the thermosetting resin composition containing the polyurethane (A) having a urethane bond and the thermosetting component (B), adhesion to the substrate, low warpage, flexibility, tin plating resistance, moisture resistance The present inventors have found that the balance between thermal properties and solder heat resistance is excellent and can solve the above problems, and have completed the present invention.

That is, this invention relates to the thermosetting resin composition shown by the following 1-14, its hardened | cured material, the soldering resist and protective film which consist of the hardened | cured material, and the printed wiring board coat | covered with the hardened | cured material.
1.1 Polyurethane (A) having two or more carboxyl groups in the molecule and having a urethane bond formed by a reaction between polycarbonate diol (a) and polyisocyanate (b), and thermosetting component ( A thermosetting resin composition comprising B).
2. 2. The thermosetting resin composition according to 1 above, wherein the polyurethane (A) has a number average molecular weight of 500 to 100,000 and an acid value of 5 to 150 mgKOH / g.
3. 2. The thermosetting resin composition according to 1, wherein the polycarbonate diol (a) has a number average molecular weight of 200 to 5,000.
4). Polycarbonate diol (a) is a repeating unit derived from a polycarbonate diol, one or more alicyclic diols containing one or more linear aliphatic diols as a structural unit. 4. The thermosetting resin composition as described in 1 or 3 above, which is at least one selected from the group consisting of polycarbonate diols containing polycarbonate and polycarbonate diols containing repeating units derived from both diols.
5. The polycarbonate diol (a) is a polycarbonate diol containing a repeating unit derived from a linear aliphatic diol and an alicyclic diol as a constitutional unit, the number average molecular weight is 400 to 2000, and the linear aliphatic 5. The thermosetting resin composition as described in 4 above, wherein the copolymerization ratio of the diol and the alicyclic diol is from 3: 7 to 7: 3 by mass ratio.
6). 2. The thermosetting resin composition according to 1, wherein the polyisocyanate (b) is an alicyclic diisocyanate derived from an alicyclic diamine.
7). 2. The thermosetting resin composition as described in 1 above, wherein the thermosetting component (B) is an epoxy resin.
8). The epoxy resin is at least one selected from the group consisting of a bisphenol S type epoxy resin, a diglycidyl phthalate resin, a heterocyclic epoxy resin, a bixylenol type epoxy resin, a biphenyl type epoxy resin, and a tetraglycidyl xylenoylethane resin. 8. The thermosetting resin composition as described in 7 above.
9. Furthermore, the thermosetting resin composition of 1 containing a hardening | curing agent.
10. 10. The thermosetting resin composition according to 9, wherein the curing agent is at least one selected from the group consisting of amines, quaternary ammonium salts, acid anhydrides, polyamides, nitrogen-containing heterocyclic compounds, and organometallic compounds.
11. Furthermore, the thermosetting resin composition of 1 containing an organic solvent.
12 A cured product obtained by curing the thermosetting resin composition according to any one of 1 to 11 above.
13. A solder resist comprising the cured product as described in 12 above.
14 13. A protective film comprising the cured product as described in 12 above.
15. 13. A printed wiring board, wherein a part or all of the surface is covered with the cured product described in 12 above.

The thermosetting resin composition containing polyurethane (A) having a urethane bond and a thermosetting component (B) according to the present invention is excellent in adhesion to a substrate, low warpage, flexibility, and tin-resistant plating. It is also excellent in heat resistance, moisture heat resistance, and solder heat resistance, and can be suitably used in fields such as electrical insulating materials such as solder resists and interlayer insulating films, IC and VLSI sealing materials, and laminates.
In the conventional solder resist, curing shrinkage and cooling shrinkage after curing are large, causing warping and causing a decrease in yield. However, according to the thermosetting resin composition of the present invention, low warpage and flexibility In addition, it is possible to achieve tin plating resistance, solder heat resistance, and moist heat resistance that are in a trade-off relationship with each other, and an excellent solder resist or protective film can be formed at low cost with high productivity.

Hereinafter, the present invention will be described in detail.
The polyurethane (A) has two or more carboxyl groups in one molecule, and has a urethane bond formed by a reaction between the polycarbonate diol (a) and the polyisocyanate (b). The polyurethane (A) is obtained, for example, by reacting at least a polycarbonate diol (a), a polyisocyanate (b), and a polyol (c) having a carboxyl group for the purpose of adjusting the acid value. In the reaction, a monohydroxyl compound (d) may be added as a terminal blocking agent.

  The polycarbonate diol (a) is derived from a polycarbonate diol (a1) containing a repeating unit derived from one or more linear aliphatic diols as a constituent unit, derived from one or more alicyclic diols. Polycarbonate diol (a2) containing as a structural unit, or polycarbonate diol (a3) containing a repeating unit derived from both of these diols as a structural unit.

  Specific examples of the polycarbonate diol (a1) containing a repeating unit derived from a linear aliphatic diol as a constituent unit include, for example, polycarbonate diol derived from 1,6-hexanediol, 1,5-pentanediol and 1 Polycarbonate diol derived from 1,6-hexanediol, polycarbonate diol derived from 1,4-butanediol and 1,6-hexanediol, 3-methyl-1,5-pentanediol and 1,6-hexanediol The polycarbonate diol derived is mentioned.

  Specific examples of the polycarbonate diol (a2) containing a repeating unit derived from an alicyclic diol as a constituent unit include, for example, a polycarbonate diol derived from 1,4-cyclohexanedimethanol.

  Specific examples of the polycarbonate diol (a3) containing repeating units derived from both a linear aliphatic diol and an alicyclic diol as constituent units include, for example, 1,6-hexanediol and 1,4-cyclohexane. Polycarbonate diols derived from dimethanol are mentioned.

  A polycarbonate diol containing a repeating unit derived from a linear aliphatic diol as a constituent unit tends to be excellent in low warpage and flexibility. Moreover, the polycarbonate diol containing a repeating unit derived from an alicyclic diol as a constituent unit tends to have high crystallinity and excellent tin plating resistance and solder heat resistance. From the above viewpoints, these polycarbonate diols can be used in combination of two or more, or polycarbonate diols containing repeating units derived from both linear aliphatic diols and alicyclic diols as constituent units can be used. . In order to achieve a good balance between low warpage and flexibility, tin plating resistance and solder heat resistance, the copolymerization ratio of the linear aliphatic diol and the alicyclic diol is 3: 7 to 7 by mass ratio. : 3 polycarbonate diol is preferably used.

  Moreover, it is preferable that the number average molecular weights of polycarbonate diol (a) are 200-5000. When the number average molecular weight is less than 200, the chemical resistance is lowered and the tin plating resistance may be impaired. If it exceeds 5,000, the relative amount of urethane bonds decreases and the acid value also decreases, so that the crosslinking density decreases and as a result, solder heat resistance may be impaired. The polycarbonate diol includes a repeating unit derived from a linear aliphatic diol and an alicyclic diol as a structural unit, and the copolymerization ratio of the linear aliphatic diol and the alicyclic diol is from 3: 7 to 7: In the case of 3, the number average molecular weight is preferably 400 to 2,000.

Specific examples of the polyisocyanate (b) include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, diphenylmethylene diisocyanate, (o, m, or p) -xylene diisocyanate, (o , M, or p) -hydrogenated xylene diisocyanate, methylene bis (cyclohexyl isocyanate), trimethylhexamethylene diisocyanate, cyclohexane-1,3-dimethylene diisocyanate, cyclohexane-1,4-dimethylene diisocyanate, 1,5-naphthalene diisocyanate, etc. Of the diisocyanate. These polyisocyanates can be used alone or in combination of two or more.
Among these, alicyclic diisocyanates derived from alicyclic diamines, specifically, isophorone diisocyanate or (o, m, or p) -hydrogenated xylene diisocyanate are preferable. When these diisocyanates are used, a cured product excellent in tin plating resistance can be obtained.

  As the polyol (c) having a carboxyl group, it is particularly preferable to use a dihydroxy aliphatic carboxylic acid having a carboxyl group. Examples of such a dihydroxyl compound include dimethylolpropionic acid and dimethylolbutanoic acid. By using a dihydroxy aliphatic carboxylic acid having a carboxyl group, the carboxyl group can be easily present in the urethane resin.

The monohydroxyl compound (d) may be a compound having one hydroxyl group in the molecule as an end-capping agent for the polyurethane (A), such as aliphatic alcohol (d1), monohydroxymono (meth). An acrylate compound (d2) etc. are mentioned.
Examples of the aliphatic alcohol (d1) include methanol, ethanol, propanol, isobutanol and the like, and examples of the monohydroxy mono (meth) acrylate compound (d2) include 2-hydroxyethyl acrylate and the like.

  The number average molecular weight of the urethane resin (A) is preferably 500 to 100,000, and more preferably 8,000 to 30,000. Here, the number average molecular weight is a value in terms of polystyrene measured by gel permeation chromatography. When the number average molecular weight of the polyurethane (A) is less than 500, the elongation, flexibility and strength of the cured film may be impaired, and when it exceeds 100,000, it may become hard and decrease flexibility.

  The acid value of the urethane resin (A) is preferably 5 to 150 mgKOH / g, more preferably 30 to 120 mgKOH / g. When the acid value is less than 5 mgKOH / g, the reactivity with the curable component is lowered, and the heat resistance may be impaired. If it exceeds 150 mgKOH / g, the resist properties such as alkali resistance and electrical properties of the cured film may be deteriorated. In addition, the acid value of resin is the value measured based on JISK5407.

  As the thermosetting component (B), an epoxy resin that reacts with the component (A) is used. Specific examples include bisphenol A type epoxy resins, hydrogenated bisphenol A type epoxy resins, brominated bisphenol A type epoxy resins, bisphenol F type epoxy resins, novolac type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, N-glycidyl type epoxy resin, bisphenol A novolac type epoxy resin, chelate type epoxy resin, glyoxal type epoxy resin, amino group-containing epoxy resin, rubber modified epoxy resin, dicyclopentadiene phenolic type epoxy resin, silicone modified epoxy resin, ε -Epoxy compounds having two or more epoxy groups in one molecule such as caprolactone-modified epoxy resin. Further, in order to impart flame retardancy, a material in which an atom such as halogen such as chlorine or bromine or phosphorus is introduced into the structure may be used. Furthermore, bisphenol S type epoxy resin, diglycidyl phthalate resin, heterocyclic epoxy resin, bixylenol type epoxy resin, biphenol type epoxy resin, tetraglycidyl xylenoyl ethane resin, and the like may be used.

In the thermosetting resin composition of the present invention, the curing component (B) is used alone or as a mixture of two or more. The amount thereof, the equivalent ratio of the epoxy groups of the (A) curable component against the carboxyl groups of component (B) is desirably 1.0 to 3.0. If it is less than 1.0, the electric insulation of the cured film of the thermosetting resin composition may be insufficient, and if it exceeds 3.0, the amount of shrinkage of the cured film increases, and as an insulating protective film of a flexible printed circuit board (FPC) When used, low warpage tends to deteriorate.

The curing agent used in the present invention accelerates the curing reaction, and is used to further improve properties such as adhesion, chemical resistance, and heat resistance. Examples of such curing agents, imidazole derivatives (e.g., manufactured by Shikoku Chemicals _{Co., 2MZ, 2E4MZ, C 11 Z} , C 17 Z, 2PZ, 1B2MZ, 2MZ-CN, 2E4MZ-CN, C 11 Z-CN, 2PZ-CN, 2PHZ-CN, 2MZ-CNS, 2E4MZ-CNS, 2PZ-CNS, 2MZ-AZINE, 2E4MZ-AZINE, C 11 Z-AZINE, 2MA-OK, 2P4MHZ, 2PHZ, 2P4BHZ , etc.); Guanamines such as acetoguanamine and benzoguanamine; polyamines such as diaminodiphenylmethane, m-phenylenediamine, m-xylenediamine, diaminodiphenylsulfone, dicyandiamide, urea, urea derivatives, melamine, polybasic hydrazide; organic acid salts and / or Or epoxy adak G; amine complex of boron trifluoride; triazine derivatives such as ethyldiamino-S-triazine, 2,4-diamino-S-triazine, 2,4-diamino-6-xylyl-S-triazine; trimethylamine, triethanol Amine, N, N-dimethyloctylamine, N-benzyldimethylamine, pyridine, N-methylmorpholine, hexa (N-methyl) melamine, 2,4,6-tris (dimethylaminophenol), tetramethylguanidine, m- Amines such as aminophenol; polyphenols such as polyvinylphenol, polyvinylphenol bromide, phenol novolak, alkylphenol novolak; organic phosphines such as tributylphosphine, triphenylphosphine, tris-2-cyanoethylphosphine; phosphonium salts such as n-butyl (2,5-dihydroxyphenyl) phosphonium bromide and hexadecyltributylphosphonium chloride; quaternary ammonium salts such as benzyltrimethylammonium chloride and phenyltributylammonium chloride; the polybasic acid anhydrides; diphenyliodonium tetra Fluoroboroate, triphenylsulfonium hexafluoroantimonate, 2,4,6-triphenylthiopyrylium hexafluorophosphate, manufactured by Ciba Geigy, Irgacure 261, manufactured by Asahi Denka Co., Ltd., Optomer-SP-170, etc. Cationic photopolymerization catalyst of styrene; maleic anhydride resin; equimolar reaction product of phenyl isocyanate and dimethylamine, tolylene diisocyanate, isophorone diisocyanate Over organic polyisocyanate and the curing agents or curing accelerators such known conventional such equimolar reaction product of dimethylamine, such bets can be mentioned.

  These curing agents can be used alone or in admixture of two or more. The use of a curing agent is not essential, but can be used in a range of up to 25 parts by mass with respect to 100 parts by mass of the curing component (B), particularly when curing is desired to be accelerated. If it exceeds 25 parts by mass, the sublimable component from the cured product increases, which is not preferable.

  The thermosetting resin composition of the present invention is obtained by dissolving or dispersing the polyurethane (A) and the thermosetting component (B) using a mixer such as a disper, a kneader, a three-roll mill, or a bead mill. It is done. In that case, you may use the solvent inactive with respect to an epoxy group and a carboxyl group.

  The organic solvent is used for easily dissolving or dispersing the polyurethane (A) and the thermosetting component (B), or adjusting the viscosity to be suitable for coating. Examples of organic solvents include toluene, xylene, ethylbenzene, nitrobenzene, cyclohexane, isophorone, diethylene glycol dimethyl ether, ethylene glycol diethyl ether, carbitol acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, dipropylene glycol methyl ether acetate, Diethylene glycol ethyl ether acetate, methyl methoxypropionate, ethyl methoxypropionate, methyl ethoxypropionate, ethyl ethoxypropionate, ethyl acetate, n-butyl acetate, isoamyl acetate, ethyl lactate, acetone, methyl ethyl ketone, cyclohexanone, N, N-dimethyl Formamide, N, N-dimethylacetamide, N- Methylpyrrolidone, .gamma.-butyrolactone, dimethyl sulfoxide, can be mentioned chloroform and methylene chloride.

Furthermore, the thermosetting composition of the present invention includes various known additives such as inorganic fillers such as barium sulfate, talc, calcium carbonate, alumina, glass powder, quartz powder, silica, glass fiber, carbon fiber, Fiber reinforcing materials such as boron nitride fibers, colorants such as titanium oxide, zinc oxide, carbon black, iron black, organic pigments, organic dyes, antioxidants such as hindered phenol compounds, phosphorus compounds, hindered amine compounds, Ultraviolet absorbers such as benzotriazole compounds and benzophenone compounds can be blended.
Moreover, a viscosity modifier, a flame retardant, an antibacterial agent, an antifungal agent, an anti-aging agent, an antistatic agent, a plasticizer, a lubricant, a foaming agent, and the like can be added and mixed according to the application.

Synthesis Example 1: Synthesis of polyurethane (PU-1) Polycarbonate diol (Ube Industries, Ltd.) derived from 1,5-pentanediol and 1,6-hexanediol in a reaction vessel equipped with a stirrer, a thermometer, and a condenser. ), PCDL800, number average molecular weight 800) 2400 g (3 mol), dimethylolpropionic acid 402 g (3 mol) as a dihydroxyl compound having a carboxyl group, isophorone diisocyanate 1554 g (7 mol) as polyisocyanate and 2-hydroxyl compound as 2-hydroxyl compound Hydroxyethyl acrylate, 238 g (2.05 mol) was added. The mixture was heated to 60 ° C. while stirring and stopped. When the temperature in the reaction vessel began to decrease, the mixture was heated again and stirred at 80 ° C., and the absorption spectrum of the isocyanate group (2280 cm ⁻¹ ) was observed in the infrared absorption spectrum. The reaction was terminated after confirming disappearance. Carbitol acetate was added so that the solid content was 50% by mass to obtain a viscous liquid polyurethane (PU-1) containing a diluent. The number average molecular weight of the obtained polyurethane was 22,000 (the average molecular weight was determined as a value converted to polystyrene using gel carrier liquid chromatography (GPC-1 manufactured by GPC Showa Denko KK)), solid acid. The value was 46 mgKOH / g.

Synthesis Example 2: Synthesis of urethane resin (PU-2) Polycarbonate diol derived from 1,6-hexanediol and 1,4-cyclohexanedimethanol as polycarbonate diol (manufactured by Ube Industries, Ltd., UM-CARB90, number) The polyurethane PU of a viscous liquid containing a diluent was synthesized by the same means as in Synthesis Example 1 except that 2700 g of an average molecular weight of 900 and the copolymerization ratio of the above two kinds of diols were 1: 1) by mass ratio. -2 was obtained. The number average molecular weight of the obtained polyurethane was 24,000, and the acid value of the solid content was 57 mgKOH / g.

Comparative Example 1:
Styrene-acrylic acid resin manufactured by Johnson Polymer Co., Ltd .; John Cryl 586 (molecular weight 4600, solid content acid value 108 mgKOH / g) was used as the carboxyl group-containing resin.

Comparative Example 2:
Acrylic copolymer resin manufactured by Daicel Chemical Industries, Ltd .; Cyclomer P ACA320 (molecular weight 20000, solid content acid value 130 mgKOH / g) was used as the carboxyl group-containing resin.

Reference Examples 1-2, Example 1 and Comparative Examples 1-2:
Each component and blending ratio shown in Table 1 were mixed with a three roll (23 ° C.) to prepare a curable resin composition. The obtained thermosetting composition was coated on a substrate with a bar coater so as to have a film thickness of about 25 μm. Each coated substrate was pre-dried at 80 ° C. for 15 minutes, and then thermally cured under conditions of 150 ° C. × 60 minutes. The performance in each example was evaluated by the following method. The results are shown in Table 1.

Performance Evaluation Method (1) Warpage Property A thermosetting composition was applied to a polyimide film (Kapton 100H; manufactured by Toray DuPont Co., Ltd., thickness 25 μm), and after thermosetting, cut to 50 mmφ with a circle cutter. What is cut into a circle exhibits a deformation in which the vicinity of the center warps in a convex or concave shape. After 1 hour, it was allowed to stand in a convex state, and the maximum and minimum values of the height of warpage from the horizontal plane were measured and averaged. The sign represents the direction of warping, and when left in a downwardly convex state, the case where the cured film is on the upper side with respect to the polyimide film is “+”, and the case where the cured film is on the lower side is “−”.
(2) Flexibility On a polyimide film (Kapton 100H; manufactured by Toray DuPont Co., Ltd., thickness: 25 μm), a sample which has been subjected to thermosetting is cut into 15 × 70 mm and 180 degrees so that the resist surface is on the outside. A force of 0.35 kN was applied to the bent part and the bent part for 1 second. Observed with a microscope, the number of times until cracks occurred was measured as flexibility. Evaluation was made up to 10 times.
(3) Solder heat resistance A portion of the rigid copper substrate was masked with a Kapton polyimide tape (manufactured by Toray DuPont Co., Ltd.), and the mask surface and non-mask surface were entirely coated to obtain a cured coating film. Next, the Kapton polyimide tape was peeled off, rosin-based flux was applied, and immersed in a solder bath at 260 ° C. for 10 seconds. The interface between the resist film and the tape peeling portion was visually observed, and the number of immersions until a change such as film peeling appeared was evaluated. Evaluation was performed up to three times.
(4) Adhesiveness Using a coating film cured on a copper substrate and a polyimide film (Kapton 300H; manufactured by Toray DuPont Co., Ltd., thickness: 100 μm), evaluation was performed based on JIS K5600. In addition, the tape for peeling used the product made from Nitto, and evaluated on the following reference | standard.
○: When the number of grids remains completely,
△: When the number of grids remains from 50 to less than 100,
×: When the number of grids remains less than 50.
(5) Pressure cooker test (PCT: wet heat resistance test)
A cured coating film was obtained on a flexible copper substrate (Ubecel N SE3150, manufactured by Ube Industries, Ltd.), and allowed to stand in a constant temperature and humidity chamber at 121 ° C. and a relative humidity of 100% RH for 120 hours, and then evaluated according to the following criteria.
○: Swelling, peeling, no discoloration on the cured coating film,
Δ: Slightly swollen, peeled, or discolored in the cured coating film,
X: The cured coating film swells, peels off and discolors.
(6) Tin plating resistance A cured coating film was obtained on a flexible copper substrate (Upicel N SE3150, manufactured by Ube Industries, Ltd.), and was plated with a tin plating solution (TINPOSIT LT-34, manufactured by Rohm & Haas). After immersion at 70 ° C. for 3 minutes, it was washed with hot water (70 ° C., 3 minutes) and visually evaluated according to the following criteria.
○: Swelling, peeling, no discoloration on the cured coating film,
Δ: Slightly swollen, peeled, or discolored in the cured coating film,
X: The cured coating film swells, peels off and discolors.

As described above, the thermosetting resin composition containing the polyurethane (A) having a urethane bond and the thermosetting component (B) according to the present invention has adhesiveness to a substrate, low warpage, flexibility, resistance to resistance. It has excellent tin plating properties, heat and humidity resistance, and solder heat resistance, and can be suitably used in fields such as electrical insulating materials such as solder resists and interlayer insulating films, IC and VLSI sealing materials, and laminates.

Claims (9)

Polyurethane (A) having two or more carboxyl groups in one molecule and having a urethane bond formed by reaction of polycarbonate diol (a) and polyisocyanate (b), and thermosetting component (B) A solder resist formed by curing a thermosetting resin composition containing
The polycarbonate diol (a) is a polycarbonate diol containing a repeating unit derived from a linear aliphatic diol and an alicyclic diol as a structural unit,
Ri epoxy resin der the thermosetting component (B) is reacted with the polyurethane (A),
The solder resist , wherein an equivalent ratio of the epoxy group of the thermosetting component (B) to the carboxyl group of the polyurethane (A) component is 1.0 to 3.0 . The solder resist according to claim 1, wherein the polyurethane (A) has a number average molecular weight of 500 to 100,000 and an acid value of 5 to 150 mgKOH / g. The solder resist according to claim 1, wherein the polycarbonate diol (a) has a number average molecular weight of 200 to 5,000. The number average molecular weight of the polycarbonate diol (a) containing a repeating unit derived from a linear aliphatic diol and an alicyclic diol is 400 to 2000, and the copolymerization ratio of the linear aliphatic diol and the alicyclic diol is The solder resist according to claim 1 , which has a mass ratio of 3: 7 to 7: 3. The solder resist according to claim 1, wherein the polyisocyanate (b) is an alicyclic diisocyanate derived from an alicyclic diamine. The epoxy resin is at least one selected from the group consisting of bisphenol S type epoxy resin, diglycidyl phthalate resin, heterocyclic epoxy resin, bixylenol type epoxy resin, biphenyl type epoxy resin, and tetraglycidyl xylenoylethane resin. The solder resist according to claim 1 . Furthermore, the soldering resist of Claim 1 containing a hardening | curing agent. The solder resist according to claim 7 , wherein the curing agent is at least one selected from the group consisting of amines, quaternary ammonium salts, acid anhydrides, polyamides, nitrogen-containing heterocyclic compounds, and organometallic compounds. Furthermore, the soldering resist of Claim 1 containing an organic solvent.