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Understanding dissipation, thermal resistance, and IC temperature (Part 1 of 2)

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mariocaptain
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Will sealing the circuit make the IC temperature rise?
mariocaptain   11/1/2013 4:50:03 AM
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Dear Hardik,


This is a great great article. I've been searching around for IC thermal resistance with makes me confused and by far this is the best article. Thank you!


I am just wondering if sealing the PCB (and the IC) will result in a rise in IC temperature.


In my application I am using a 2N2222 transistor to drive a small load (around 30mA). Given the calculated power dissipation & the ambient temperature range, the Junction temperature of the transistor should not exceed 100 degrees C in any circumstances, which is well below the max allowable junction temperature of 150 degrees C of the transistor.

I need to water proof the circuit by epoxy resin and from what I learned from your article, this could make the junction temp to rise. My reasoning is: by potting the circuit, basically I am prolonging the path from junction to ambient ("thermal ground") and therefore the junction temperature will rise.

Is it correct?

Thanks in advance for any advice.

Dave

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