Patent ID: 6655024
Filing Date: 2003-12-02
Classification: H05K,Y10T

Abstract:
A method for manufacturing a circuit board comprising the steps of:forming a lower conductor connection on a substrate; applying a photosensitive resin on the lower conductor connection and drying the photosensitive resin to form a photosensitive resin film; exposing the photosensitive resin film via hole a photomask for patterning, and developing and drying the photosensitive resin film so as to form an insulating resin film including a through-hole for defining a via hole, the through-hole having an inverted-trapezoidal cross-section taken in the direction of the substrate thickness and a sloped inner wall tilted at a tilt angle &thgr; with respect to the substrate; and forming an upper conductor connection on the insulating resin film so as to connect the upper conductor connection to the lower conductor connection through the through-hole in the insulating resin film, wherein the photomask has 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, wherein the tilt angle &thgr;, which is determined using a polynomial approximation of degree n: f&af;(s)=Î¸=Ï†&it;&Sum;k=0n&it;Ck&it;skwherein s is the width of the light-shielding strips and &PHgr; is a constant relating to the exposure conditions, is in the range of about 0.17 rad