Direct Writing of Silver-Seed Paths for Electroless Copper Deposition Using Laser-Induced Forward Transfer

In recent years much research focused on using laser-induced forward transfer (LIFT) for direct writing of electric circuits. However, the generation of conductive paths is extremely challenging. Laser irradiation typically causes donors of thin metallic films to separate into nano and micro particles. Thus, metallic pastes have become the donor material of choice for LIFT. Due to the flexibility of the pastes, it is also a promising fabrication technique for generating circuits for smart or e-textiles. However, it is extremely challenging to maintain the conductivity on stretchable fabrics. To overcome this problem, techniques surrounding the fibres with metal, such as electroless metal deposition, are advantageous. To generate circuits, this technique requires the printing of seed paths consisting e.g. of silver nano particles. This is the point where the original LIFT of thin metallic films, which enables direct writing of paths of nano and micro particles, finds a novel and promising application field. In the present paper we present a parametric study to optimise particle formation and present initial results of conductive paths generated utilizing LIFT to form Ag seed paths for electroless copper deposition.