Black Al₂O₃ Ceramic Packaging Materials And Co-fired Ceramic Multilayer Substrates

The present paper reviewed the development of research on electronic packaging materials and technologies. The important role of black alumina ceramics and its background of application were indicated. Black alumina ceramics, as a kind of ceramic packaging materials, has lower density than general metal materials and better properties for application than plastic, so it plays an unshakable role when packaging materials are required with high properties in the aspects of reliability, thermostabilization and hermetization. Some electronic components cannot be exposed to light and black alumina ceramics help to satisfy the demand. Black alumina ceramics also have advantages of lower cost, the ease of their fabrication, and so on, compared with other ceramic materials.In this paper, black alumina ceramics were made proportionally from super fine powder ofα-Al2O3, SiO2 and some transitional metal oxides such as Co2O3, Cr2O3, V2O5, MnO2 and TiO2 by conventional ceramic techniques and sintered at 1350℃in the air ambient. The effect of several kinds of doping on black alumina ceramics was investigated. It was indicated that SiO2 is the right doping for back alumina ceramics: It not only lowered the sintering temperature of black alumina ceramics, but also improved the electrical properties of the samples. When w(SiO2)/% was 1.5%, the density of the sample of black alumina ceramics was up to 3.78 g/cm3, the porosity was 0.12% and the resistivity was 2.5×1010 ?·cm, theεr and tgδof the samples were 13.68 and 0.0226 respectively. B2O3-doping on the black alumina ceramics further lowered the sintering temperature to 1320℃and did no harm to its electrical properties. When w(B2O3)/% was 2.0%, the density of the sample of black alumina ceramics was 3.77 g/cm3 and the porosity 0.17%. Theεr and tgδof the samples were 12.05 and 0.0142 respectively. CuO intensively lowered the sintering temperature of alumina ceramics. We also got black alumina ceramics composition by CuO-doping in alumina, but the black color of the samples from CuO wasn't stable as that from Co2O3 et al and CuO harmed the electrical properties of the alumina ceramics.We also investigated the technics of multilayer co-fired ceramics. Pieces of green ceramics were obtained by means of tape-casting, and they were then punched mechanically. Electrode paste was made by mixing powders of metal W and some kinds of organic materials proportionally. The paste was then printed on the tapes of green ceramics. Four layers of the tape were laminated correctly and then pressured at 80℃. Subsequently the target samples were sintered in N2 ambient, finally we got the co-fired Al2O3 multilayer substrates.