Embedding resin, circuit board, electronic module, and method for manufacturing circuit board

Abstract

In a structure in which a resin fills in gaps between wiring patterns, the resin is adjusted in advance so as to reduce the influence of stress in the filling resin. The resin that is to fill in gaps between wiring patterns of a circuit board is an embedding resin with a coefficient of linear expansion and a Young's modulus such that, in a stack in which a base substrate, an insulating layer and a resin portion formed of the embedding resin are stacked in this order, stress at an interface of the insulating layer that is in contact with the resin portion is at most 13.0 MPa. This stress is calculated by the formula σ=(P/bh)+(Ey/R), which is based on a 4-layer model using a temperature difference between room temperature and a glass transition temperature of the insulating resin. σ represents stress (MPa), P represents axial force (N), b represents a depth measurement of the insulating layer (mm), h represents a thickness of the insulating layer (mm), E represents the Young's modulus (MPa), y represents distance from a neutral plane (mm) and R represents a radius of curvature (mm).

Dependencies are inferred from the claim text.