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Other Parts Discussed in Thread: TMP102-Q1, TMP102


I would like to use tmp102-q1 in my LED flash light application. I am planning to place the sensors on the same side of the LEDs and as close as possible to LEDs. As per SBOS702B  page 22 (layout guidelines) a 'Ground Plane is used for Thermal Coupling to Heat Source'.

Do I have to open the solder mask under the IC to ensure max. heat exchange between GND plane and IC?



  • Hi Eldho,


    I've consulted with my teammate, Mayrim, and here is our input:


    The dominant thermal path is the ground pin; the conduction through packaging is secondary which is really what the question is about.


    With that being said, generally speaking it is better to open up the solder mask directly under a device, provided there is direct contact between the copper plate and the device, especially for devices that have exposed pad. Solder or thermal paste can be applied to ensure close contact.


    The situation here is different since most likely there will be no thermal grease, and definitely there is no solder. The body of TMP102 is slightly raised from the plane it is sitting on, so there might be an air gap between copper pattern and TMP102. Although varying, most solder mask is thicker than this gap. It is better to be in contact with solder mask than with air gap. The thermal conductivity of solder mask material, although poor, is still many times better than that of air.



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