Photosensitive resin composition, photosensitive dry film, and pattern formation method

A photosensitive resin composition comprising

• (A) a polymer comprising repeat units having the formula (A1) and repeat units of at least one type selected from repeat units having the formula (A2) and repeat units having the formula (A3), shown below,
• (B) an epoxy compound containing on the average at least four epoxy groups per molecule,
• (C) a photoacid generator,
• (D) a benzotriazole compound and/or imidazole compound, and
• (E) an organic solvent,
• wherein X1 and X2 are each independently hydrogen or glycidyl group,
• Y1 is a C1-C5 alkanediyl group,
• Z1 is a C1-C10 straight alkanediyl group which may contain hydroxy, a C2-C10 branched alkanediyl group, or a divalent group having the formula (A4):
• wherein Z11 and Z13 are each independently a C1-C5 alkanediyl group, Z12 is a C1-C30 hydrocarbylene group, a4 and a5 are each independently an integer of 1 to 50,
• Z2 and Z3 are each independently a single bond or a C1-C10 alkanediyl group,
• R1, R2, R3, and R4 are each independently hydrogen or a C1-C10 hydrocarbyl group,
• a1, a2, and a3 are numbers in the range:
• 0<a1<1, 0≤a2<1, 0≤a3<1, and a1+a2+a3=1,
• x and y are each independently an integer of 1 to 50.