The Melexis Technologies MLX90614 Family Infrared Thermometer Sensor is a good option if you are looking for a high precision non-contact temperature measurement sensor. Both the IR sensitive thermopile detector chip and the signal conditioning ASSP are integrated in the same TO-39 can.
Two options for evaluation boards are available here: Eval Boards for MLX90614
Melexis’ application note, Soldering Techniques for TO39 IR Sensor Products can be downloaded via the link.
During soldering, if peak solder temperature is higher than 225°C, or if going through a wash, the IR window cannot get wet or over heated, hence the need for a cap. The cap or cover would need to be totally sealed.
For example, when using MLX90614ESF-AAA-000-TU, a ID=3/8” cap is recommended.
The TO-39 can would be placed manually. Melexis recommends that you use a spacer as well, such as one of the options found here: Parametric Spacer Search Results