External Cooling Concept

Thermoelectric Cooling Solutions

TO56/TO9 Laser Diode

(or similar object)

Center Hole

for LD wires feed

through

TE Cooler

(Cut view)

Thermal

Contact area

Heatsink

Heatsink

Description

“External cooling” with center-hole thermoelectric coolers is the solution for objects without a possibility to integrate

TEC inside (or where a built-in TEC is not sufficient enough because of large heatload). For example there is a wide

range of uncooled LD types that use industrial standard TO-56 or TO-9 headers. The typical design and pins

layout for such headers assume uncooled solution with no space to integrate a thermoelectric cooler directly on a

header. In the same time thermal stabilisation can improve LD performance and lifetime and give additional features

in final application. In such cases the “external” thermoelectric cooling can be an optimal choice. TEC has a center

hole (or multiple holes) to feed LD pins through and provide a thermal contact between header and cold side

surface. Center-hole TECs and “external” cooling are optimal for creating environmental testing setups for LD

manufacturers, laboratory researches and temperature sensitive experiments.

Application Tips

1. An appropriate heatsink is required to be attached to TE cooler hot side. TEC operates as a heatpump. The

heat pumped from TEC cold side has to be spread from a hot side with a heatsink.

2. TEC built it on a header (internal cooling) is more optimal solution by power consumption comparing with

“external” one (TEC under the header). The external cooling is good if there is no way to integrate a suitable TE

cooler on a header. The external cooling can be an extension for standard un-cooled packaged devices.

3. With the external cooling the temperature on TEC cold side may differ from temperature of the object inside a

packaged assembly. This is a result of header thermal resistance availability.

4. Recommended methods of mounting: thermal grease or gluing. In case of Copper or Aluminium heatsink

materials it is strongly recommended to use a thermal grease or elastic silicon-based thermoconductive glues.

Copper and Aluminium heatsink materials have high thermal expansion coefficient (CTE), different to TEC

materials.

Final product item

(packaged assembly

on a header)

“External” TE Cooling

TEC cools the entire

assembly

“Internal” TE Cooling

TEC on a header, cools the

heat-generating object directly

Heatsink

Heatsink

!

Copyright 2014. RMT Ltd. The design and specifications of products can be changed by RMT Ltd without notice.

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