Circuit board and manufacturing method therefor

摘要

A method for manufacturing a circuit board having a through-hole for defining via hole, which has a sloped inner wall tilted at a desired tilt angle theta, is provided. The through-hole has an inverted-trapezoidal cross-section and is made using a photomask having a via hole pattern including a light-shielding pattern corresponding to the bottom of the through-hole, and pluralities of light-shielding strips and translucent strips which are arranged alternately and substantially parallel to one another, the pluralities of light-shielding strips and translucent strips corresponding to the sloped inner wall of the through-hole. The tilt angle theta is determined using a polynomial approximation of degree n: 1 $f\left(s\right)=\mathrm{theta}=\phi it\sum _{k=0}^{n}it{C}_{k}it{s}^k$ wherein s is the width of the light-shielding strips and phi is a constant relating to the exposure conditions, and is in the range of about 0.17 rad