Thermoelectric Cooling Solutions

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Thermoelectric sub-assemblies

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TO-66 Sub-Mounts

TO-66 header is a “diamond”-like analog of TO-8 header. Like TO-8 header it’s a very common header type in laser and photodetector applications. The material of TO-66 header is usually cold rolled steel (CRS) or Kovar coated with nickel and gold for base and pins. The number of pins is up to 9 (usually 6 or 9 pins). Header version with 9 pins is standard and mostly requested. Other types available by request. For different dimensional modification of TO-66 header surface open for mounting TECs is different. The standard surface open for mounting is about 7.0×7.0 mm2, which is enough for mounting a wide range of TECs without contacting with pin’s isolation. 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-66 headers with 9 pins. The complete list of possible solutions is wider. TO-66 header is suitable for any thermoelectric cooler with hot side dimensions up to 7.0×7.0 mm2. Please, contact RMT Ltd in case if specific solution on TO-66 is required.

Single-stage TECs
2-stage TECs
3-stage TECs
4-stage TECs

Exterior Type dTmax
1MD04-031-xx (n=31)
Click to enlarge. 1MD04-031-05 59 2.5 1.2 3.6 3.22 5.0 5.0 1.6 Datasheet
1MD04-031-08 64 1.8 0.8 1.9
1MD04-031-10 66 1.5 0.7 2.1
1MD04-031-12 67 1.3 0.6 2.3
1MD04-031-15 69 1.0 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-66 Kovar base thermal resistance (Rt) is included into specified performance values. TO-66 sub-assembly is required to be attached to an appropriate heatsink to spread the heat, pumped from LD (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-66 header. Press the On-Line Assistant link and specify hot side dimensions as 7.0×7.0 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 mounting on TO-66 package. The datasheets for not listed TO-66 sub-assemblies are available by request.

Headers Available

It's a typical drawing of TO-66 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-66 headers. The company doesn’t manufacture the headers or provide headers separately. The mounting service is also available on Customer’s headers upon request.

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