I want to calculate how much would be the difference in temperatures between top and bottom surface of a 750um thick SiN. I am using the formula
Q=KA dT/t
then dT=Q/mc (to find the difference in temperatures)
Is this the right way to do it or I have to take into account other factors also. I am asking this because the answer I get does not looks good. Thank you.
Hi,
Thank you very much for your answer,
One question, the power(1W) that I put on the top of SiN is not different than how will it be transferred into the SiN? I think I would need to find first the rate of heat flow within SiN and then I can find the dT, what's your take on that.
I say it does not look good because I get huge difference in temperatures at both ends of SiN.
One more point I think I missed is the area of Laser spot that is given to heat the substrate. I think assuming that whole substrate is uniformly heated is not correct, it is only a particular area that is responsible for this heat flow within the SiN, and then there comes a lateral heat flow which cannot be ignored also and I have no idea, how can I put this lateral heat flow into equation.
I thank you again for your answer.
Yes, that will complicate things up, but if at first, I focus on heat transfer within SiN only, assuming a constant 280°C is coming at a certain area A, lets take out the
The answer that I got was 254°C difference between the two surface which I believe is too big for 750um SiN. When I check with PT100 the top surface temperature, it shows 100°C or 120°C depending on the connection. What I put in my first equation (Q=KA dT/t) in place of dT, I take 280-26 (280°C being given from bottom surface and 26°C surface temperature (as room temperature is 26)). So taking this 26°C as the top surface temperature is making things bad?
If I don't take this temperature then, I have two variables in the equation, Q and dT.
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