Patent ID: 8693211

Claim:
A wiring substrate, comprising: a wiring substrate main body having a semiconductor element mounting area in which a semiconductor element is mounted; a wiring pattern provided on a first surface of the wiring substrate main body at a portion corresponding to the semiconductor element mounting area, and having connection portions to which the semiconductor element is flip-chip bonded; a solder resist provided on the first surface of the wiring substrate main body, and an inner wall of the solder resist defining an opening portion whose size is substantially equal to the semiconductor element mounting area, when viewed from a top; and a dam provided on an upper surface of the solder resist so as to surround the semiconductor element mounting area, for blocking an underfill resin provided in a clearance between the semiconductor element and the wiring substrate main body, wherein a distance between the inner wall of the solder resist defining the opening portion and an inner wall of the dam is varied, an underfill resin feeding area, from which the underfill resin is fed, is defined at a portion of a clearance between the semiconductor element and the wiring substrate main body, a first distance is defined between the inner wall of the opening portion of the solder resist and the inner wall of the dam in the underfill resin feeding area, a second distance is defined between the inner wall of the opening portion of the solder resist and the inner wall of the dam in an area other than the underfill resin feeding area, the first distance is larger than the second distance, and the inner wall of the dam is formed such that the distance between the inner wall of the opening portion of the solder resist and the inner wall of the dam decreases stepwisely or continuously from the first distance to the second distance.