Effect of UV irradiation on electroless Cu–Ni–P plating on cycloolefin polymer

Abstract

Polytetrafluoroethylene is one of the leading candidates for a low dielectric constant material. The authors have studied metallisation by electroless deposition followed by electroplating on cycloolefin polymer (COP), an alternative material which has similar electrical characteristics to polytetrafluoroethylene. Conventionally, a microroughened surface has to be created by a strong etching medium in order to achieve a good adhesion between the deposited metal and insulating resin. However, this etched surface results in transmission loss due to the skin effect. Thus, the authors focussed on the applicability of UV irradiation for modification of the COP resin, avoiding the roughness of the surface. Around 0·8 kN m–1 of peel strength between the deposited copper top layer and the COP substrate was obtained through applying the modification by UV irradiation and electroless Cu–Ni–P plating as a seed layer deposition on to the irradiated COP. The insulation resistance using a comb pattern was also measured <100 V and gave a sufficient value (1·7 × 1013 Ω) without migration of copper.