TABLE OF CONTENTS The substrate is the foundation of an electronic circuit and must perform many functions. It acts as the platform upon which to mount components and must be compatible with the processes intended to metallize the substrate and to attach the components to the metallized traces. The substrate may also be an integral part of the overall circuit package.
The desirable properties of a substrate for electronic applications include
High electrical resistivity. A substrate must have high electrical resistivity to isolate adjacent circuitry.
High thermal conductivity. High thermal conductivity assists in transporting the heat generated by electronic components during normal operation away from the components.
Resistance to temperature. Many of the processes used to metallize substrates and assemble the components take place at elevated temperatures.
Inert to chemical corrosion. Solvents, fluxes, and the like are harsh and must not attack the chemical structure of the substrate.
Cost. The cost of the substrate material must be compatible with the cost of the end product.
The properties of ceramic substrates are advantageous for many microelectronic systems, ranging from simple, inexpensive circuits used in throwaway toys to elaborate multilayer structures used in space or medical applications. Only by understanding the properties of ceramic substrates can they be optimally utilized in this wide variety of applications.
Ceramics are crystalline in nature, with very few free electrons. They have high electrical resistivity, are chemically and thermally very stable, and have a high melting point. They...
