Huirong He, Jida Chen, Shengtao Zhang, Minhui Liao, Lingxing Li, Wei He, Yuanming Chen and Shijin Chen
This paper aims to propose a modified full-additive method (MFAM) to fabricate fine copper lines for high density interconnection (HDI) printed circuit boards (PCBs). In addition…
Abstract
Purpose
This paper aims to propose a modified full-additive method (MFAM) to fabricate fine copper lines for high density interconnection (HDI) printed circuit boards (PCBs). In addition, the surface of the fine copper lines is treated with a brown oxidation process to obtain good adhesion between the copper and the dielectric resin.
Design/methodology/approach
Fine copper lines fabricated by MFAM were observed to evaluate the undercut quality, in comparison to undercut quality of copper lines fabricated by the semi-additive method and the subtractive method. The effect of the thickness of the dry film on the quality of the copper plating was investigated to obtain the regular shape of fine lines. The fine copper lines treated with the brown oxidation process were also examined to generate a coarse surface microstructure to improve the adhesion between the copper and the dielectric resin. The cross section and surface of as-fabricated fine copper lines were characterized using an optical microscope, a scanning electron microscope and an atomic force microscope.
Findings
MFAM has the potential to fabricate high-performance fine copper lines for HDI PCBs. Undercut of as-fabricated fine copper lines could be prevented to meet the design requirement of impedance. In addition, fine copper lines exhibit enough adhesive force to laminate with dielectric resin after the brown oxidation process.
Originality/value
MFAM, with the advantages of high efficiency and being a facile process, is developed to fabricate high-quality fine copper lines for industrial HDI PCB manufacture.