Effects of laser surface modification on the adhesion strength and fracture mechanism of electroless-plated coatings

The adhesion strength between the circuit and substrate is a key factor that affects the performance of electronics. Laser modification assisted metallization technology (LAM), which can fabricate high-adhesion metallic pattern on ceramic without masks, is generally considered as a promising selective metallizing method. However, it seems lack of the reports about how the texturing patterns affect the coating adhesion on ceramic up to now. In this paper, three kinds of texturing patterns—parallel groove texture (PGT), parallel wave texture (PWT) and square net texture (SNT) with different laser scanning spacings (D) were fabricated on ceramic substrates by laser modification, and the copper was selectively electroless-plated on the textured surface. Then, the influences of textures on the adhesion strength and fracture mechanism of copper-ceramic were studied systematically. Results indicated that the adhesion were significantly affected by the surface area, microstructures and structural defects of the textures. Compared with PGTs and PWTs, SNTs showed a more significant effect on improving the adhesion, in which a reliable obtuse-angled anchoring bond was generated at D = 60 μm (sample SN60), making the fracture take place at the copper, ceramic and copper-ceramic interface simultaneously, and the maximum adhesion strength as high as 43.2 MPa was obtained. • High-adhesion copper patterns were fabricated efficiently on alumina ceramic. • Effects of different texturing patterns on the adhesion were investigated. • Fracture mechanisms of copper-ceramic were studied by observing the fracture surfaces. • A reliable obtuse-angled anchoring bond that caused mixed fracture was prepared.