Package Sealing

• Heat pumps should be operated in a dry, hermetically sealed environment otherwise moisture can condense and freeze around the micro-pillars. This can cause cracks to form in the micro-pillars, compromising the integrity of the heat pump.
• Some solid-state heat pumps include a sealing method to protect the micro-pillars and junctions within the heat pump assembly from moisture and other elements. Epoxy, silicon or conformal coatings are used to form the protective layer surrounding the micro-pillars. While these sealing methods help protect the heat pump module from moisture, the user should contact Redfish Photonics to determine if this is sufficient protection for specific applications.
• Adhesives are commonly used for hermetically sealing caps and lids to headers and packages. The seal should be leak tight to 1 X 10^-8 cc/sec He. Resistance welding and laser welding are also widely used.
• When joining headers to caps through a weld process ensure that the weld surfaces are flat. This will protect against unwanted torque that can compromise cap/window seals. Prior to welding verify that the temperature limits of the package components are compatible with the temperature of the weld process.
• To ensure a dry internal package environment a vacuum bake is recommended for sub-assemblies prior to cap or lid sealing. Contact Redfish Photonics if instructions are needed.