Thick-film paste manufacturing processes

Aluminum nitride has been demonstrated to be suitable for blank substrates for high power and high frequency applications. Substrates from many sources are available for thick or thin film metaUization. Thick film paste manufacturers now supply pastes formulated for aluminum nitride. The multilayer process described in the previous section has also been adapted for aluminum nitride. Both multilayer substrates and packages are available commercially. 

Metallization methods for alumina ceramics using conductive paste can be broadly classified into two types thick film processing and cofiring (HTCC). Although both methods share many points of similarity in the printing process, big differences can be seen in the other manufacturing processes. 

The process for the thennal sensor network is as follows. Organic diodes, to be used as sheet-type thermal sensors, are manufactured on an ITO-coated PEN film. A 30-mn thick p-type semiconductor of copper phthalocyanine (CuPc) and a 50-nm thick n-type semiconductor of 3,4,9,10-perylene-tetracarboxylic-diimide (PTCDI) are deposited by vacuum sublimation. A 150-mn thick gold film is then deposited to form cathode electrodes having an area of 0.19 mm. The film with the organic diodes is coated with a 2-pm thick parylene layer and the electronic interconnections are made by the method similar to that mentioned before. The diode film is also mechanically processed to form net-shaped structures. Finally, to complete the thermal sensor network, we laminated the transistor and diode net films together with silver paste patterned by a microdispenser. This is shown in Figure 6.3.11. 

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