| 摘要 |
PURPOSE: To obtain a manufacturing method of a buildup multilayer wiring board whereby blind via holes can be formed at a high density therein and their reliabilities are improved too. CONSTITUTION: On a double-sided printed board 11 provided with inner layer circuit patterns 12 on both sides, photosensitive insulation layers 13 are so laminated that the inner layer circuit patterns 12 is covered therewith, and by the exposures, developments and peelings of the photosensitive insulation layers 13, through holes 13a are formed in the photosensitive layers 13 on the inner layer circuit patterns 12. Further, by a milling machine 20, the inner peripheral surface of each formed through hole 13a is so counterbored as to be changed into an inclined surface 13b whose inner diameter is increased with its departing from the inner layer circuit pattern 12. Thereafter, on the photosensitive insulation layer 13 and on each inner circuit pattern 12 in each through hole 13a, an outer layer circuit pattern 14 is laminated. Thereby, a blind via hole 15 whereby the outer layer circuit pattern 14 and each inner layer circuit pattern 12 are connected directly through each through hole 13a is formed. |
