Furnace and laser methods of bonding metals to ceramics: phenomenological investigation

Several methods for direct bonding of metals to ceramics in air and various inert atmospheres using a furnace or lasers as a heating source are invest igated. In order to investigate inter-diffusion between the copper layer an d the sapphire and also to measure the percentage of diffused copper in sap phire, Rutherford backscattering spectroscopy (RBS) was performed. Based on heat transfer theory and on diffusion theory. a model was derived to expla in and predict the behavior of furnace and laser beam bonding of metals to ceramics. Thr predictions of the model are in agreement with the experiment al percentages of diffused copper in sapphire obtained in the RES investiga tions. Based on experimental investigations and theoretical modeling, it ha s been concluded that the direct bonding phenomenon is a thermal effect, si milar to transient liquid phase bonding. The major advantage of direct bond ing is that no filler material is required between the metallic member and the ceramic substrate. Finally, the method of direct bonding of metals to c eramics using a laser beam is capable of directly drawing a metallic patter n on a ceramic substrate. (C) 2000 Elsevier Science S.A. All rights reserve d.