Photosensitive resin composition, photosensitive element, method for forming resist pattern and method for producing printed wiring board

1. A method of forming a resist pattern, comprising:

forming a photosensitive layer comprising a photosensitive resin composition on a substrate, wherein the photosensitive resin composition comprises:

(A) a binder polymer;

(B) a photopolymerizable compound that has an ethylenically unsaturated bond;

(C1) a compound represented by general formula (1) below,

wherein, at least one R represents a C 4-12 alkyl group; the sum of a, b, and c is 1 to 6; and when the sum of a, b, and c is 2 to 6, each R may be the same as or different from one another; and

(C2) a 2,4,5-triarylimidazole dimer or a derivative thereof,

wherein the content of the component (C1) is 0.05 to 0.8 mass parts per 100 mass parts of the total content of components (A) and (B), and the content of the component (C2) is 3 to 5 mass parts per 100 mass parts of the total content of components (A) and (B)

exposing prescribed regions of the photosensitive layer to light by a direct exposure imaging technique; and

developing the exposed photosensitive layer to form a resist pattern.

2. The method of forming a resist pattern according to claim 1 , wherein component (A) comprises an acrylic-type polymer that has as constituent units thereof a monomer unit derived from acrylic acid and/or methacrylic acid and a monomer unit derived from alkyl ester of acrylic acid and/or alkyl ester of methacrylic acid.

3. The method of forming a resist pattern according to claim 1 , wherein the content of the component (B) is 20 to 80 mass parts per 100 mass parts of the total content of components (A) and (B).

4. The method of forming a resist pattern according to claim 1 , wherein the sum of a, b, and c is 1 or 2.

5. The method of forming a resist pattern according to claim 1 , wherein said direct exposure imaging technique includes exposure to laser light having a peak in the wavelength range from at least 350 nm to less than 440 nm.

6. A method of producing a printed wiring board, comprising:

performing the method of forming a resist pattern according to claim 1 ; and

forming a conductor pattern on the substrate based on said resist pattern.

7. The method of forming a resist pattern according to claim 1 , wherein the component (C2) is at least one selected from the group consisting of 2-(o-chlorophenyl)-4,5-di(methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, and 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer.

8. The method of forming a resist pattern according to claim 1 , wherein the photosensitive resin composition further includes (D) leuco crystal violet.

9. The method of forming a resist pattern according to claim 8 , wherein the leuco crystal violet is included in an amount of 0.05 to 5 mass parts per 100 mass parts of the total of components (A) and (B).

10. The method of forming a resist pattern according to claim 1 , wherein a weight-average molecular weight of component (A) of the photosensitive resin composition is 40000 to 80000.