HEADERS MATERIALS

In most applications of miniature single and  mulistage TECs they are integrated into packages of devices (laser, detectors and so on).

The package design is very important for thermal management of such cooling system.

The package is a thermal barrier between TEC and heat sink. The barrier causes overheating of hot side of TEC which leads to decreasing cooling efficiency - more power consumption and less cooling performance..

Effective transfer of heat generated by TEC to heat sink through the package is very important for cooling performance.

A huge range of electronic packages are used in optoelectronics where TECs are integrated. Different materials are used for such packages. Among them typical metals such as kovar, CRS, Cu-Mo, Cu-W, some types of ceramics and others.

Thermal properties of some widely used materials are advised in the table.

Although for miniature packages such as most of TO-style the Kovar is usual material of base, but it has lowest thermal conductivity.

Most optimal are modern composite materials Co-W and Co-Mo as such materials have optimal combination of thermal performance and thermal expansion coordinated with TEC ceramics.

Material

Thermal Conductivity W/mK

CTE х10-6

1/K

Kovar

17

5,5

Cold-Rolled Steel (CRS)

50

11,5

Stainless steel

14,5

17,1

Copper-Mo

175

8,0

Co-W

180

6,7

Example

Cooling of laser diode in TO3 type package with single-stage TEC, RMT type 1MC06-046-05.

Heat sink temperature 75°C, laser chip is kept at 35°C by the single stage TEC.

Base material with low thermoconductivity leads to large overheating of TEC hot side.

It is a reason of reduction of TEC cooling performance.

As shown in the picture the power consumption significantly depends on thermal properties of material of package.

 

 

State-of-art composite materials such as Copper-Tungsten and  Copper-Molybdenum are preferable for such applications