| 摘要 |
PROBLEM TO BE SOLVED: To provide a method to completely fill through-holes with copper in manufacturing a printed circuit board having the through-holes.SOLUTION: The wall of each through-hole is coated with electroless copper or flash copper, and then, a pulse plating method is performed as follows: a board is immersed into a copper plating bath having an anode, forward current density is applied thereto for a predetermined period, and then the forward current density is cut off for a predetermined period; and second forward current density is applied thereto for a predetermined period, and then the second forward current density is cut off for a predetermined period. The pulse plating cycle which is repeated allows the through-hole to be filled with copper in the method. The current density is in a range of 0.1-5 ASD, preferably 0.5-3 ASD, and desirably, it is applied for a period of 10-200 msec, preferably for a period of 20-100 msec. Desirably, it is cut off for a period of 0.5-5 msec, preferably for a period of 1-2 msec.SELECTED DRAWING: Figure 1 |
