| 摘要 |
PROBLEM TO BE SOLVED: To provide a multilayer printed circuit board wherein diameter of through holes of each layer is different from one another, and to provide its perforating method.SOLUTION: This multilayer printed circuit board includes a first circuit board, a second circuit board adjacent to the first circuit board, and a through hole penetrating the first circuit board and the second circuit board. The diameter of the through hole in the first circuit board is larger than the diameter of the through hole in the second circuit board. The perforating method of the multilayer printed circuit board includes: a step wherein the first circuit board and the second circuit board of the multilayer printed circuit board are so drilled as to be penetrated with a first drill to bore a first through hole in the multilayer printed circuit board; and a step wherein the first circuit board is so drilled as to penetrate along the first through hole with a second drill having a diameter larger than that of the first drill, and drilling is finished when the second drill reaches the upper surface of the second circuit board. |
