Enhanced adhesion strength of silver paste on AlN ceramic substrate via sintered nano-CuO

We have optimized a CuO-doped silver paste to significantly improve the adhesion strength of silver thick film on AlN ceramic substrate, which can be widely applied in power electronic packaging applications. Via a combination of scanning electron microscope and X-ray diffraction, we have systematically studied the silver layer morphology on top of AlN ceramic substrate, and the interphases between the silver thick film and AlN substrate. Due to the CuAl2O4 intermediate formed at the silver layer/AlN interface, the adhesion strength of silver thick film can be greatly improved. Particularly, the silver paste with 3 wt% nano-CuO sintered on AlN ceramic substrate exhibits high adhesion strength of 15.3 MPa with good electrical conductivity of 0.9 mΩ/□.