| 摘要 |
PROBLEM TO BE SOLVED: To provide a multilayer printed wiring board which forms a through hole in which a hole diameter in a central portion in a thickness direction of an inner layer laminated substrate is smaller than an opening diameter with higher accuracy than conventional one, and enhances conduction reliability of a plating layer of the through hole.SOLUTION: A multilayer printed wiring board has a through hole formed by being subjected to laser processing at a desired position of an inner layer laminated substrate from one surface. The through hole is formed through a desmear treatment from an opening of the inner layer laminated substrate into such a shape that an opening diameter decreases from the opening of front and rear surfaces of the inner layer laminated substrate toward the central portion in the thickness direction of the inner layer laminated substrate. The through hole is filled with the conductor layer, the conductor layer of the front and rear surfaces of the inner layer laminated substrate is conducted by a conductor layer of the through hole, and an insulating resin layer, a conductor pattern and a via hole are formed on the front and rear surfaces of the inner layer laminated substrate.SELECTED DRAWING: Figure 1 |
