Patent ID: 7615707

Claim:
A printed circuit board (PCB), comprising: a substrate comprising a through hole, wherein one side of the through hole of the substrate corresponds to a first diameter, the other side of the through hole of the substrate corresponds to a second diameter, and the through hole comprises: a first part corresponding to the first diameter; and a second part corresponding to the second diameter; a metal conductor, filled in the second part; a blocking material, filled in the first part to separate a first surface of the substrate from a second surface of the substrate, wherein the blocking material filled in the first part is closer to the first surface than to the second surface, and the metal conductor filled in the second part is closer to the second surface than to the first surface; a conductive layer comprising a first portion, a second portion, and a third portion, wherein the third portion is placed on an inner surface of the through hole, the first and second portions are placed on the first and second surfaces respectively, the first and second portions are both electrically connected to the third portion, and the first portion acts as a conductive ring; an anti-soldering material placed on the blocking material and the conductive ring to cover the blocking material and the conductive ring completely, wherein the anti-soldering material does not cover an entire area of the first surface; and at least an electronic component of an application circuit, mounted on the first surface and electrically connected to the first portion placed on the first surface; wherein the second diameter is greater than the first diameter.