Mechanical and Physical Properties of Ceramic Substrates

The ceramic surface finish is a function of the microgranular structure and the density of the ceramic-glass composite. Small grains, in as-fired ceramic structures, form a smooth surface, and are mainly used for thin-film or fine-line thick-film applications. The centerline average (CLA) is a measure of ceramic surface requirement, 0.381-1 pm (15 0 pin.) for thick-film surface requirement, and 0.127 pm (5 pin.) and less for thin-film surface requirement. It is important to realize that the glass inclusion degrades both the electrical and the thermal properties of the ceramic substrates. 

Camber (pm/mm) is defined as the overall deviation from one side of the substrate to the other side as measured along the diagonal of the surface. Substrates 635 pm (25 mil) thick with 1-3 pm/mm (1-3 mil/in.) camber are available as standard. AIN substrates may possess a camber less than 3 pm/ mm. The specific gravity is the ratio of the material density to that of the water density. 

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