Study On The Mix Combined Thick Film Metallization Paste Applies To AlN

This paper is based on the study of preparation technology, composition and performance of the thick-film paste. The thick-film metallization pastes on AlN substrate have been mainly studied. Techniques such as sol-gel, wet milling, screen printing and sintering were used for sample preparation. Effects of process, glass and reactive binders on the properties of thick film have been analyzed with XRD, SEM, TG-DSC and electrical tests.Glass binder prepared by sol-gel method has been investigated. It was showed that a glass of low melting point can be obtained when the composition according to (wt%)CaO(40), B₂O₃(15), SiO₂(35), BaO(10).The technical control of the paste viscosity has been investigated. It was showed that the paste was suitable to be printed when the viscosity controlled between 150～240Pa·s. Effects of surfactant and dispersion on the leveling of thick-film paste were investigated. Effects of the components and contents of binders on the thick film properties have been investigated. It was found that when the glass content was 10%, film adhesion strength achieve maximum (11.6MPa). In addition, it was proved that the square resistance would be higher when glass content was higher. XRD analysis indicated that the existence of 2Al2O3·B2O3 which has been reacted by reactive binder TiB2 and AlN substrate enhances the mechanical interlocking between metal film and the AlN substrate.Effects of the mixture of glass and TiB₂ on the thick film properties have been discussed. It was found that the electrical performance and adhesion strength when the mixed collaboration of glass and reactive binder was better than single binder. The best technique is successfully developed to produce the silver thick film: mix the Ag, TiB2, glass and organic vehicle together first, the percents of them are 74.25%, 0.75%, 5%, 20%;sinter the thick film in air from room temperature to 600℃, then sinter and bake it at 850℃for 10 minutes in N₂ atmosphere. Under this technique, the thick film is dense and bright, and its adhesion strength is up to 12.3MPa and the resistance is 8.9mΩ/â–¡.