300 Degree Celsius Electronic Component Packaging

Characterizing geothermal wells and their surrounding geothermal formations requires the use of electronic subsurface logging tools that monitor conditions (e.g. temperature, pressure, flow, fluid chemistry); unfortunately, few electronics can gather and transmit accurate data at temperatures exceeding 200 ˚C. The most common workaround is to place a low temperature electronic device inside a vacuum flask, which slows the migration of heat transfer from the surrounding rock formation, but the drawback to this approach is that the tool is limited to a few hours of operation before it needs to be removed from the geothermal well. Enhanced geothermal systems require long-term characterization, with tools and downhole monitoring systems that can be emplaced for months at a time. At Sandia National Laboratories, the Geothermal Department is focused on developing subsurface tools that can operate for a month or more at temperatures reaching 300 ˚C. At present, we are developing a range of electronic packaging techniques that integrate off-the-shelf high-temperature surface mount integrated circuits onto ceramic printed circuit boards, with gold-tin solder and wire bonding, along with a conformal coating to improve reliability. These four-packaging techniques have been evaluated at 300 ˚C towards the goal of demonstrating a 300 ˚C datalink that uses a RelChip RC10001 microcontroller for geothermal well evaluation.