Heat-conducting and insulating diamond composite material substrate as well as preparation method and application thereof

The invention relates to a heat-conducting and insulating diamond composite material substrate and a preparation method and application thereof. The method comprises the following steps: taking a diamond copper composite material and/or a diamond aluminum composite material as a heat-conducting base material; sequentially preparing an aluminum nitride insulating layer, a metal transition layer and a welding layer seed layer on the heat-conducting base material through a magnetron sputtering method; and a welding layer is prepared on the welding layer seed layer through an acid electroplating method, and the heat conduction and insulation diamond composite material substrate is prepared. According to the heat-conducting and insulating diamond composite material substrate prepared by the invention, the high-insulation requirement of a chip on a chip substrate can be realized, the breakdown-resistant voltage can reach 0.5-1000kV, meanwhile, the heat conductivity requirement of 200W/(m.K) or even 400W/(m.K) or ab