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A copper electroplating formula for BVHs and THs filling at one process

Jia Liu (School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, China)
Jida Chen (School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, China)
Zhu Zhang (School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, China)
Jiali Yang (School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, China)
Wei He (School of Microelectronics and Solid-State Electronics, University of Electronic Science and Technology, Chengdu, China)
Shijin Chen (Bomin Electronic Co., Ltd, Meizhou City, China)

Circuit World

ISSN: 0305-6120

Article publication date: 1 August 2016

297

Abstract

Purpose

The purpose of this paper is to introduce a new copper electroplating formula which is able to fill blind microvias (BVHs) and through holes (THs) at one process through a direct current (DC) plating method.

Design/methodology/approach

Test boards of printed circuit board (PCB) fragments with BVHs and THs for filling plating are designed. The filling plating is conducted in a DC plating device, and the filling processes and influence factors on filling effect of BVHs and THs are investigated. Dimple depths, surface copper thickness, thermal shock and thermal cycle test are applied to characterize filling effect and reliability. In addition, to overcome thickness, increase of copper on board surface during filling plating of BVHs and THs, a simple process called pattern plating, is put forwarded; a four-layered PCB with surface copper thickness less than 12 μm is successfully produced.

Findings

The filling plating with the new copper electroplating formula is potential to replace the conventional filling process of BVHs and THs of PCB and, most importantly, the problem of thickness increase of copper on board surface after filling process is overcome if a pattern plating process is applied.

Research limitations/implications

The dimple depth of BVHs and THs after filling plating is not small enough, though it meets the requirements, and the smallest diameter and largest depth of holes studied are 75 and 200 μm, respectively. Hence, the possibility for filling holes of much more small in diameter and large in depth with the plating formula should be further studied.

Originality/value

The paper introduces a new copper electroplating formula which achieves BVHs and THs filling at one process through a DC plating method. It overall reduces production processes and improved reliability of products resulting in production cost saving and production efficiency improvement.

Keywords

Acknowledgements

The authors gratefully acknowledge the support from Guangdong Province of Ministry of Education (No. 2012A090300007) and the Funds of Large Apparatus and Equipment of Chongqing University (201406150020).

Citation

Liu, J., Chen, J., Zhang, Z., Yang, J., He, W. and Chen, S. (2016), "A copper electroplating formula for BVHs and THs filling at one process", Circuit World, Vol. 42 No. 3, pp. 141-151. https://doi.org/10.1108/CW-10-2015-0049

Publisher

:

Emerald Group Publishing Limited

Copyright © 2016, Emerald Group Publishing Limited

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