Thermoelectric Cooling Solutions

site map eng | ru

Thermoelectric sub-assemblies

Print version

TO-39 Sub-Mounts

TO-39 header is a very small package for cooling solutions in laser diodes (including VCSEL and DBF lasers), avalanche photodiodes and sensor applications. The material of TO-39 header is usually Kovar or CRS coated with nickel and gold for base and pins. RMT Ltd offers thermoelectric sub-assemblies on TO-39 header with 6 or 8 pins. Header version with 8 pins is standard and mostly requested. TO-39 header with 6 pins is available as a cost-effective solution. Pins can be standard (cylindrical form) or with flattening ends modified to simplify wire bonding process. The header surface open for mounting is about 3.2×3.2 mm2, which is enough to mounting various single- and multi-stage TECs types. RMT Ltd offers different solutions with single-stage and multistage TECs available.

Sub-Assembly Overview

Standard Sub-Assemblies Solutions

This is a list of standard, most common solutions with thermoelectric coolers mounted on TO-39 header with 8 pins. The complete list of possible solutions is wider. TO-39 header is suitable for any thermoelectric cooler with hot side dimensions up to 3.2×3.2 mm2. Please, contact RMT Ltd in case if specific solution on TO-39 is required.

Single-stage TECs
2-stage TECs

Exterior Type dTmax
1MC04-007-xx (n=7)
Click to enlarge. 1MC04-007-05 65 0.7 1.4 0.8 5.64 3.2 3.2 1.6 Datasheet
1MC04-007-08 68 0.5 1.0 1.9
1MC04-007-10 69 0.4 0.8 2.1
1MC04-007-12 69 0.3 0.6 2.3
1MC04-007-15 70 0.3 0.5 2.6

TEC performance parameters are specified at standard conditions (+27°C, vacuum). The datasheet for each sub-assembly contains also the additional data, specified at +50°C, N2. Please, download the datasheet for detailed info. The affect from TO-39 Kovar base thermal resistance (Rt) is included into specified performance values. TO-39 sub-assembly is required to be attached to an appropriate heat sink to spread the heat, pumped from laser diode or another source and thermoelectric cooler. Heatsink thermal resistance may affect on performance, and is required to be as low as possible. Heatsink thermal resistance influence is not included into specified performance data.

You may use TEC Select Assistant to find other thermoelectric coolers suitable for TO-39 header. Press the On-Line Assistant link and specify hot side dimensions as 3.2×3.2 mm2 as a main search criteria. The cooling capacity of TEC is recommended to be as at least 2 times higher than expected heat load in the application. For example, for 2W estimated heat load, please, specify TEC Qmax as at least 4W in the search field. The assistant will specify all thermoelectric coolers compatible for installing on TO-39 package. The datasheets for not listed TO-39 sub-assemblies are available by request.

Headers Available

It's a typical drawing of TO-39 header. The header dimensions may vary to a small extent, depending on the manufacturer.


Note: RMT Ltd provides the sub-assemblies - thermoelectric coolers, mounted on TO-39 headers. The company doesn’t manufacture the headers or provide headers separately. The mounting service is also available on Customer’s headers upon request.

Contact us at

Information furnished by RMT Ltd is reliable. However no responsibility is assumed for possible inaccuracies or omission. Specifications are subject to change without notice.