SMTA International Conference Proceedings

Evaluation of Direct Metallization Technology Plating Properties with Excellent Material Selectivity

Authors: Takuya Komeda, Tetsuji Ishida, Hisamitsu Yamamoto
Company: C. Uyemura & Co., Ltd.
Date Published: 9/22/2019   Conference: SMTA International

Abstract: A novel direct metallization technology has been developed for flex and rigid -flex printed circuit boards with excellent material selectivity. The process adsorbs a colloidal palladium catalyst only onto the resin. This is followed by the deposition of a conductive film on the catalyzed surface. No catalyst or conductive film are adsorbed on the copper surface.

This selectivity makes subsequent electrolytic copper plating produce a low profile deposit on the rolled annealed (RA) copper foil that is free of any surface metallization deposit.

In contrast, when electroless copper is used for metallization, it is also deposited on the copper surface giving rise to a higher profile abnormal appearance of electrolytic copper plating.

Using this novel direct metallization technology, good coverage was obtained in via holes and through holes. In addition, high connection reliability between the inner copper layer and the electrolytic copper plating was attained, due to absence of any contaminants on the inner copper layer.

Key Words: 

flex printed circuit boards, rigid-flex printed circuit boards, direct metallization technology, selective plating, formaldehyde free

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