For each Thermoelectric Cooler product family, Laird Thermal Systems offers standard finishing options for lapping, sealing, and soldering. Standard lapping tolerances of Thermoelectric Coolers are plus or minus ten-thousandths of an inch. This is sufficient for most applications where mounting of one Thermoelectric Cooler is used. Tighter lapping tolerances are required for mounting multiple Thermoelectric Coolers under one heat exchanger. For two modules wired in an array, Laird Thermal Systems recommends the lapping tolerance to be plus or minus one-thousandth of an inch, and for three or more modules plus or minus a half thousandths of an inch. This tolerance specification is recommended to maintain good thermal contact between the Thermoelectric Cooler and the heat exchanger. Laird Thermal Systems also offers metallization on the hot and cold side of the ceramic substrates in order to accommodate pre-tinning with Indium Tin or Bismuth Tin eutectic type solder. This is offered to accommodate applications requiring soldering of Thermoelectric Coolers onto the heat exchanger surface versus mechanical fastening.