the characteristics of high mechanical strength, high rigidity, withstanding thermal shocks and corrosion, high dielectric strength, high isolativity, a lower loss in high frequency, high thermal conductivity and vacuum tightness, corrosion -resistant, non-deformation, electrical insulation. They are widely applied in electrical vacuum devices, I.C. chip setting, power transistors and solid integrated devices. Ceramic surface after metallization can be connected to metals by brazing. It has been widely used in vacuum electronic components, conductor base, resistor base, I.C. substrates, etc.