Heatsink Selection

• Heat is generated by the device being cooled and also by the thermoelectric cooler. Select a heatsink that is adequate to dissipate all of the heat generated by the sources. The heatsink represents the final thermal resistance to the atmosphere, so its design is critical to the performance and longevity of the device. Inadequate heatsink design, mounting or size will reduce the heat pump performance and possibly that of adjacent components.
• Mount the heatsink directly to the back of the package (in most cases where the pins protrude).
• See recommendations for Surface Preparations noted above.
• An interface material such as (Thermal Compound from Wakefield Engineering, and others) is necessary between the back of the package and the heatsink. To maintain a consistent thermal path beyond five (5) years a thermal pad must be used in place of thermal compound. This will increase the thermal resistance and thereby reduce the cooler delta T by as much as ten (10) percent but can increase the device lifetime if properly assembled and tightened when installed into the heatsink assembly.
• The connecting pins or leads that protrude from the back of the package or header are hermetically sealed with a glass-filled feed through. Complete the assembly of the heatsink, including the final torque of the mounting screws prior to soldering these pins into place. Failure to mount the heatsink before soldering the pins can put stress onto the glass joint as the heatsink is tightened and lead to a hermetic seal failure. Avoid bending the pins. If they must be bent, use a pair of bending pliers or tweezers to isolate the bend area from the glass-filled seal.