Selective Electroless Copper Plating on Poly(ethylene terephthalate) Surfaces by Microcontact Printing

Microcontact printing (mu CP) is incorporated with electroless plating to fabricate the micrometer (and submicrometer) scale pattern of copper on poly(ethylene terephthalate) surfaces. Copper patterns with featured sizes ranging from 0.45 to 10 mu m are fabricated by two different procedures: the printing adhesion layer (PAL) and printing masking layer (PML) methods. The PAL method applies mu CP to directly print the siloxane-containing functional group for further catalyst adhesion and electroless plating. The PML method uses mu CP to print the octadecyltrichlorosilane self-assembled monolayer as a masking layer, which prevents the stamped regions from any further catalyst adhesion. Therefore, the catalyst adhesion would occur in the unstamped regions. Consequently, copper would deposit in these catalyst-adsorbed regions via electroless plating. The PML method has a better selectivity of copper deposition than the PAL method. In addition, the variation in deposited copper properties as a function of the plating time and temperature is discussed.