Thermal Protection Methods for Electronics in Hot Wells

This article reviews the criteria and constraints used to successfully design thermal protection for down-hole tools and electronic instruments that make high-quality measurements in hot geothermal wells. Imposed thermal, mechanical, and chemical environments and design methods for obtaining highly reliable electronic operation are described. The two main approaches for thermally protecting electronics and ensuring operation at high temperatures are (1) to use ?>temperature-hardened?> electronics below its specified temperature limit, or (2) to use conventional electronics with thermal protection, either a passive thermal protection system using insulation and heat sinking or an active refrigeration system. The technology related to both approaches for thermal protection and the choices among thermal protection methods are reviewed.