Patent ID: 6940023
Filing Date: 2005-09-06
Classification: H05K

Abstract:
1. A board having a multi-layered pattern structure comprised of N layer patterns electrically insulated from one another wherein N is an integer equal to or greater than 3, wherein the multi-layered pattern structure is formed with a through-hole, into which an electrode of an electronic part is to be inserted, an external land is formed on a surface of each of the first and N-th layer patterns, an electrically conductive layer is formed on an inner wall of the through-hole such that the electrically conductive layer is electrically connected to the external land of each of the first and N-th layer patterns, the electronic part is fixed in the through-hole with lead-free solder filled in the through-hole, and at least one internal land extending inwardly of the multi-layered pattern structure from the electrically conductive layer is formed in the same layer as a M-th layer pattern (2=<M=<(N−1)) such that the internal land is not electrically connected to the M-th layer pattern; wherein, the internal land is in the form of a ring including the through-hole as a central opening, and the internal land has a width equal to or greater than about 0.10 mm and equal to or smaller than 1.5 R wherein the width is defined as a difference between a radius of the through-hole and an outer radius of the internal land and R indicates a radius of the through-hole.