Wiring board and mounting structure using it

摘要

PROBLEM TO BE SOLVED: To easily insert an optical fiber into a wiring board and easily fix it in a vertical direction. A wiring board 2 is located on an insulating substrate 20 including a plurality of insulating layers 221 and upper and lower surfaces, a mounting area X located on the upper surface of the insulating substrate, and upper and lower surfaces of the respective insulating layers. , A wiring conductor 222 including a plurality of pads 222a located in a mounting area. The insulating substrate has a through hole 24 penetrating from the lower surface to the upper surface. The through hole is a first portion 24a having a first opening 241 on the lower surface, a second portion 24b having a second opening 242 in the mounting region on the upper surface, and a third portion located between the first portion and the second portion. It has 24c and. The average diameter of the second part is smaller than the average diameter of the first part. The third portion includes a portion whose diameter decreases in the direction from the first portion to the second portion. [Selection diagram] Fig. 1