Cu patterns with high adhesion strength and fine resolution directly fabricated on ceramic boards by ultrafast laser modification assisted metallization

Abstract

Laser modification assisted metallization technology (LAM) is a two-step method to fabricate metallic patterns on ceramic substrates by using laser selective activation and the subsequent electroless plating, which has received widespread attentions in recent years. In this paper, a picosecond laser (ps ~ laser) was first selected as the energy source for LAM to modify the alumina substrates coated with PdCl2 films, the adhesion strength, fracture mechanism and deposition resolution of the subsequent electroless-plated Cu coating, as well as the laser-alumina interaction mechanisms were studied systematically and compared with those obtained by nanosecond laser assisted metallization technology (ns ~ LAM). The results indicated that the textures with higher surface area and no thermal cracks were fabricated on the ceramic surface treated by ps ~ laser, making the adhesion strength of the Cu coating enhanced to as high as 51.1 MPa, in which a mixed failure mode was obtained. Moreover, the minimum width of Cu line fabricated by ps ~ LAM was only about 29 μm, which was much lower than the 47–53 μm that obtained by ns ~ LAM, and even comparable to the laser spot diameter. Therefore, the ultrafast-laser based LAM technology shows potential in enhancing the performance of circuits on ceramic boards.