SMTA International Conference Proceedings

Innovatve Acid Copper Process for Simultaneously Filling Vias and Plating Through Holes

Authors: Maria Nikolova, Ph.D., Confesol Rodriguez, Kesheng Feng, Ph.D., William Bowerman, Jim Watkowski
Company: MacDermid Enthone Electronics Solutions
Date Published: 9/17/2017   Conference: SMTA International

Abstract: This paper relates to copper plating processes in the manufacturing of printed circuit boards, IC substrates, and semiconducting devices for electronic applications. The innovative plating process is particularly useful for filling recessed structures with copper, such as vias and plating of through holes.

The increased demand for electronic devices in recent years has led to an extensive research in the field to meet the requirements of the industry. Aqueous acid plating baths for electrolytic deposition of copper have been very important in the manufacturing of PCB and IC substrates where fine structures like blind micro vias (BMV), trenches, through holes (TH), and pillar bumps need to be filled or build up with copper. The complex circuit board designs require simultaneously filling of via structures and plating TH. This is highly challenging since the commonly used electrolytes for filling vias are not suitable for plating of the through holes and vice versa. The requirements include filling BMV, while depositing no more than 18 - 20 µm of copper onto the planar substrate areas, dimple no more than 10 µm, and micro-distribution for the plated TH => 75 - 80%.

The described DC acid copper plating process is designed for simultaneously filling blind micro-vias and plating through holes across a variety of geometries in a variety of equipment applications with insoluble anodes, including vertical continuous plating equipment, VCP. The bath produces a bright, fine grained, ductile deposit. The thermal and physical mechanical properties of the copper deposits are excellent. Tensile strength => 42,000 psi and elongation > 20 % had been measured for deposits plated in a fresh and in an aged bath. The organic additive ranges have been optimized. All bath components are CVS analyzable and the electrolyte has an extremely long life.

Key Words: 

copper electroplating, via fill, through hole plating, metallization

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