Interconnect Materials And Processes For Packaging Thick Film Hic

Thick film hybrid integrated circuit is an important part of microelectronictechniques, which is widely applied in civil, military and aerospace satellite fields.Compared with thin film technique, thick film technique owns many advantages such aseasy process, low cost and especially cheap equipments. Among the thick techniques,electrical conductive pastes are one of the most important materials. It is necessary tostudy on sintering and soldering properties of the electrical conductive pastes due totheir mechanical and electric connections for microelectronics. In this paper, themorphology, composition and mechanical properties of6177T-Pd-Ag and4093-Pt-Pd-Ag pads are investigated by corresponding techniques. Meanwhile, the fine sinteringand soldering processes are obtained and it is very significant to direct the actualproduction.The thickness of the thick film pads is about20μm, which are fabricated bysintering the electrical conductive pastes on96%alumina ceramic substrates. Thesintering and soldering processes of the chick film pads are mainly studied. Consideredmorphology, composition and mechanical properties, the best electrical conductivepaste is4093-Pt-Pd-Ag. Then, current protectors are soldered on thick film pads usingSn62Pb36Ag2, and the joints have perfect properties. This process could greatly shortenthe production cycles and reduce the cost.Upon the thick film sintering process, there are two different processes, such asprocess A and process B，which were explained in my paper. Process B is simple andcould shorten the production cycles via studying the morphology of the differentsintering processes. In this paper, reflow soldering is relatively simple among the threedifferent soldering processes such as reflow soldering, manual soldering and vaporphase soldering. Compared with6177T-Pd-Ag, the sintering bonding strength of4093-Pt-Pd-Ag is high because of the Pt inhibiting effect to Ag diffusion. However, it mayreduce the electrical conduction property of thick film.In the view of morphology, the elements diffusion between thick film pads andsolder alloy is the inner reason that the property of joints reduces. Fortunately, it can beeffectively relieved by choosing inhibiting elements and corresponding solder material.On the micro level, the accumulation of the active time and number of thermal cyclingis the main external reasons that the property of joints reduces. Merely, it can bereduced by strictly controlling sintering and soldering process in order to avoid over-temperature. In order to obtain perfect joints, process B,96%alumina,4093-Pt-Pd-Agthick film electrical conductive pastes, Sn-Pb-Ag soldering paste and reflow solderingprocess should be applied.