Patent ID: 6753480
Filing Date: 2004-06-22
Classification: H01L,H05K,Y10T

Abstract:
A printed circuit board having a permanent solder mask comprising:a substrate made of a material including a first resin, said substrate having top and bottom surfaces, a first conductive pattern disposed on said top surface and having an unsheltered portion and a sheltered portion; a first solder mask made of a second resin having a thermal expansion coefficient substantially identical to that of said first resin of said substrate, said first solder mask coated on said top surface to form a layer having a predetermined thickness and a smooth outer surface is formed thereon; said sheltered portion covered by said first solder mask and said unsheltered portion exposed outside; and the difference between the thickness of the highest position of said first solder mask to the lowest position of said first solder mask being equal to or less than 10 &mgr;m when measured over a length of 500 mm.