Thin Film Hybrid Circuits on AIN Substrates

The compatibility of available AIN substrate materials with thin film metallisation processes is briefly discussed. The AIN material is shown to be covered with a very thin oxide layer. NiCr and NiCr‐Ni‐Au layers have been deposited onto the substrates; the adhesion between these layers and the ceramic is tested. In the substrate, via‐holes have been made by laser drilling, and the influences of the ambient gas atmosphere on the creation of such via‐holes have been observed. Advantages and limitations of the different methods of producing via‐holes that can be metallised are discussed. A high density hybrid circuit module on AIN is demonstrated.