Ceramic substrate, conductive vias

In thick-film technology, new materials and unique process techniques have been developed to fill thermal vias in alumina ceramic substrates, as a lower-cost alternative to high-thermal-conductivity ceramics [26]. Also, new materials are now available that expand the use of aluminum nitride (AIN) thick-film ceramic for high-power-dissipation applications. 

The basic manufacturing process for multilayer ceramic substrates is shown in Figure 1.3 [16]. First, the ceramic powder and organic binder are mixed to make a milky slurry. The slurry is cast into tape using the doctor blade method, to obtain a raw ceramic sheet (green sheet) that before firing, is flexible like paper. Vias for conduction between layers and wiring patterns... 

In a ceramic electrochemical reactor oxygen activation is physically separate from substrate activation. Activation of dioxygen occurs at a cathodic surface, oxygen traverses the electrolyte as oxide ions, the ions react with a substrate on the anodic face, and the electrons return to complete the circuit. Two types of electrochemical membrane reactors are under study which differ in the route by which the electrons travel from anode to cathode these are illustrated schematically in Figure 1. In the shorted fuel cell reactor the electrons return through an external circuit, from which electrical power can be extracted. Electroceramic membranes allow the electrons to make their way from anode to cathode via electrically conductive phases within the membrane proper. 

A description of the application of ceramic and photopolymer technologies to achieve high-resolution electronic patterns follows. The first section discusses ceramic dielectric vias, and the second, conductive circuitry. Improved photosensitive ceramic coating compositions and more particularly, compositions that function as precursors to fired dielectric ceramics, are mainly useful in preparation of multilayer thick-film substrates. 

When LTCCs are used as substrates for LSI high density packaging, they must release the heat generated by the chips efficiently, and since ceramic dielectrics have low thermal conductivity, special thermal conduction paths called thermal vias are often formed in the LTCC. In this case, high thermal conductivity metals with excellent heat transference are required as conductive materials. 

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