Enhancing peel strength between liquid crystal polymer and copper with plasma treatment, surface oxidation, and silane coating

Abstract

Liquid crystal polymer (LCP) has been employed as a major type of substrate in flexible printed circuit manufacturing due to its excellent electrical and mechanical properties. In order to improve the peel strength of LCP to copper, a three‐step process was proposed in this study. In the process, the surface of LCP was treated with oxygen plasma to create holes and increase the number of hydrophilic groups. The surface of copper was then oxidized and coated with silane coupling agent. Above surface treatment aimed to introduce amine group to facilitate the interconnection between copper and LCP and improve the surface roughness of the copper surface. The final samples were laminated by the above treated copper and LCP. In this study, different oxidation conditions were explored to analyze the morphology and composition of the copper surface after oxidation. The maximum peel strength of the sample prepared by this process was 8.92 N cm−1. This developed process can effectively reduce product thickness compared to current methods in industry and can reduce lamination temperature compared to previous studies.