Galvanic process for filling through-holes with metals, in particular of printed circuit boards with copper

摘要

The present invention relates to a galvanic process for filling through-holes with metals. The process is particularly suitable for filling through-holes of printed circuit boards with copper. The process comprises the following steps: (i) formation of a narrow part in the center of a through-hole by electroplating; and (ii) filling the through-hole obtained in step (i) with metal by electroplating.

主权项

1. Galvanic process for filling through-holes of a workpiece with metals comprising the following steps:
(i) bringing in contact the workpiece containing through-holes with a first metal deposition electrolyte and applying a voltage between the workpiece and at least one anode so that a current flow is supplied to the workpiece, wherein the current flow is chosen such that a deposition occurs in the center of the through-holes and, consequently, the through-holes grow together, until the through-holes are divided into two halves forming two holes which are each closed at one end close to the through-hole center, one hole on each side of the workpiece; (ii) further bringing in contact the workpiece with a second metal-deposition electrolyte and applying a voltage between the workpiece and at least one anode so that a current flow is supplied to the workpiece, wherein the through-holes obtained in step (i) which are divided into two halves are filled by the metal, wherein the current flow in accordance with step (i) is a pulse reverse current and in every cycle of the current at least one forward current pulse and at least one reverse current pulse occurs and that the current flow in accordance with step (ii) is either a pulse reverse current, a direct current or an alternating current, and wherein, in the pulse reverse current of step (i) and in the pulse reverse current of step (ii) when present, the ratio of the duration of the at least one forward current pulse to the duration of the at least one reverse current pulse is adjusted to 5-75, wherein the electrolyte comprises a wetting agent, and wherein the through-holes have a diameter of 30 μm-300 μm and a maximum height of 0.025-1 mm.