No abstract

Simple versatile processes combining plasma treatments, micro-contact printing (mCP) or ink-jet printing (IJP), and electroless deposition (ELD) have been developed to produce micrometer and sub-micrometer scale metal (Ni, Ag) patterns at the surface of polymer substrates. Plasma treatments were mainly used to graft the substrate surfaces with either nitrogen-containing functionalities on which a palladium-based catalyst can be subsequently chemisorbed (case of Ni deposition through a tin-free process in solution) or oxygen-containing functionalities on which a tin-based sensitization agent can be subsequently chemisorbed (case of Ag deposition through a redox reaction). mCP of the catalyst or of self-assembled monolayers (SAMs) as well as ink printing were used to obtain locally active or non-active areas at the polymer surfaces. The metal micro-patterns were characterized using optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Surface chemical characterization was carried out by X-ray photoelectron spectroscopy (XPS).

The aim of this paper is to report on the use of Microcontact Printing (μCP) for the manufacturing of 3D Molded Interconnects Devices. Two different approaches are reported. A first one is based on the total metallization of the polymer, μCP of the 3D pattern followed by the wet etching of the non-protected areas of the part (the so-called indirect process). A second approach is based on the combination of radio-frequency (RF) plasma treatment, μCP of a pattern of catalysts on the polymer and metallization by electroless deposition (the so-called direct process). This second process allows metallization of bare polymer parts (free of catalytic species in the bulk) with conductive 3D networks ready for the assembly of SMD devices. Examples of MID devices made with both approaches are reported. Key points like thickness (up to 12-15 μm), conductivity and adhesion of the metallic network are also reviewed. Printing on slope surfaces is demonstrated. Advantages and drawbacks of both processes are discussed.