Most applications operate in a room temperature environment and cool to below the dew point. As a result, moisture in the environment will condense onto the cold side heat exchanger and may accumulate around the mounting hardware and eventually penetrate to the thermoelectric cooler. The presence of moisture will cause corrosion that will degrade the useful life of a module. Laird Thermal Systems offers two types of perimeter sealants to protect against condensation. Silicone (RTV) is an all purpose sealant that exhibits good sealing characteristics and retains its elastomeric properties over a wide temperature range, -60ºC to 204°C. The sealant is non-corrosive and exhibits good electrical properties with low thermal conductivity. It is suitable for high volume applications for ease of use and cost effectiveness. However, over time, it is pervious to vapor migration which can actually trap small amounts of moisture inside the Thermoelectric Cooler once the vapor condenses. This may or may not be a problem depending on life expectancy of the application and environmental condition. Epoxy (EP) is an effective barrier to moisture that exhibits a useable temperature range of -55ºC to 150°C. When cured, the material is completely uni-cellular, and therefore, moisture absorption is negligible. EP material exhibits a low dielectric constant, low coefficient of thermal expansion, and low shrinkage. Epoxies are ideal for applications requiring long life expectancies. However, applying epoxy onto thermoelectric coolers can be cumbersome as multiple fillers are required to be mixed and working life tends to be short, which makes it more difficult to automate for higher volume production runs.