Adhesion improvement of electroless copper plating on phenolic resin matrix composite through a tin-free sensitization process

In order to improve the adhesion of electroless copper plating on phenolic resin matrix composite (PRMC), a new and efficient tin-free sensitization process has been developed. Electroless copper plating could be achieved in three steps, namely: (i) chemical etching with potassium permanganate solution; (ii) sensitization and activation with glucose and silver nitrate solution respectively; and (iii) electroless copper plating. Compared with the sample sensitized with stannous chloride (SnCl2), the copper plating obtained in the tin-free process showed excellent adhesion with the PRMC substrate, but had lower plating rate and conductivity. Additionally, the morphology of the copper plating was affected by the sensitization process, and the tin-free process was conducive to the formation of the large spherical copper polycrystal. Although the process is slightly complicated, the new sensitization process is so low-cost and environment-friendly that it is of great significance and could be applied into large-scale commercial manufacturing.

► A tin-free sensitization process for electroless copper plating was developed. ► Discussed the reactions of phenolic resin possibly occurred during the etching process. ► Glucose used as sensitizer can improve the adhesion of copper plating. ► The adhesion improvement was attributed to the anchor effect of concave holes. ► The distribution of catalyst particles affected the properties of plating.