RESIN COMPOSITION LAYER

PROBLEM TO BE SOLVED: To provide a resin composition layer capable of obtaining an insulating layer which can suppress a haloing phenomenon even when a thickness is thin and can form a via hole having a good shape.SOLUTION: A resin composition layer contains a resin composition and has a thickness of 15 micro m or less, and the resin composition contains (A) an epoxy resin, (B) an aromatic hydrocarbon resin containing an aromatic ring having two or more hydroxyl groups as a monocycle or condensed ring, and (C) an inorganic filler having at least one of an average particle diameter of 100 nm or less and a specific surface area of 15 m/g or more.SELECTED DRAWING: Figure 1