Copper Plating on Liquid Crystal Polymer by Wet Pretreatment

Abstract

The material of a printed circuit board corresponding to the high frequency band needs to have a low dielectric constant and a low dielectric loss tangent. Liquid crystal polymer (LCP) is one candidate material. However, LCP is a difficult material to plate on, and current pretreatment involves a long time in highly concentrated alkaline treatment to roughen the surface before plating. However, there is concern about transmission loss resulting from the roughened surface. In this study, in order to improve these problems, we investigated a pretreatment process that combined an alkaline treatment, a mild acidity permanganate treatment, and a silane coupling treatment. We report that this process makes it possible to form electroless copper-plated films with good adhesion on low-roughness LCP surfaces.