| abstract |
A hardening body capable of improving the adhesion between an insulating layer and a metal layer and reducing the surface roughness of the insulating layer is provided. The cured product according to the present invention is a cured product of a resin composition comprising an epoxy compound, a curing agent, an inorganic filler, and a polyimide, wherein the content of the inorganic filler is 30% by weight or more and 90% by weight or less in 100% by weight of the cured product, The hardened body has a sea-island structure having an anatomy and a sea-islanding part, the average long diameter of the island-causing part is 5 µm or less, and the island-independent part includes the polyimide. |