Ceramic Substrate

Introduction

• Most commonly made of Alumina

• AlN or BeO also used

• Ceramic layers placed together and fired in high temperature oven

• Metal traces usually made of Tungsten or Molybdenum

• Ceramic substrates have good thermal properties; used for high power packages

Figure 4-41. Ceramic Substrate

General Thermal Considerations

Ceramic substrates are good conductors. Thus they offer a relatively low thermal resistance. This also makes them excellent spreaders of heat.

Modeling Options

Due to the high conductivity of the ceramic substrate, the substrate usually offers a relatively low thermal resistance. The metallic traces within the substrate can also be ignored for most purposes.

FloTHERM PACK creates a substrate as a single block with an isotropic conductivity of the particular ceramic material chosen. Metal traces and signal vias, which do not affect the thermal performance of the substrate significantly, are ignored.

Material Properties

Thermal conductivities:

Alumina: 18 W/(m.K)

Validation & References

1. Gary Kromann, Thermal Management of a C4/Ceramic-Ball-Grid-Array: The Motorola PowerPC 603 and 604 RISC Microprocessors, Proceedings of SEMITHERM, 1996.