Brazing of alumina ceramics modified by pulsed plasma beams combined with arc PVD treatment

A new method of preparing alumina ceramic surface for brazing it to kovar with conventional Ag-Cu. eutectic brazes is presented. The key concept of this approach consists in formation of two inter-layers on the ceramic surface: (i) thin (in nm scale) layer of TiOx using pulse plasma beams, and (ii) thicker (about 2 mum) layer of TiO. or metallic Ti using arc PVD technique. Grazing angle X-ray diffraction (GXRD) analysis shows that the first layer consists most likely of Ti7O13, whereas the second is either Ti2O or metallic Ti-depending on the deposition conditions. Commercial housings of semiconductor diodes have been used as the samples. Brazed housings were-tested under routine industrial conditions. The ultimate tensile strength (UTS) of joints reaches the average value of 90 MPa. Vacuum tightness is better than 5 x 10(-6) mbar (.) l/s. The values of both parameters are sufficient to pass the production requirements. (C) 2003 Elsevier Science Ltd. All rights reserved.