Learning Forum

[Mustafa Alsayed]

Hallo,
I do now Hotplate. I have already the design, I wonder why the line in substrate (purple) not straight, why there is angle? Is this because of  isolation? 
another question, what is the degree of freedom for this design in this case, could you explain to me, how can I find the degree of freedom?

[peteroznewman]

Are you asking why the 54.7 degree angle is not 90 degrees?  Whoever designed this part decided that was a good angle. Why do you think 90 degrees would be better?

In a Steady State Thermal analysis, the Degree of Freedom at each node is the Temperature of that node.  That is what the solver is trying to compute, the temperature at each node given the loads and boundary condtions applied at various faces or bodies.

[Mustafa Alsayed]

exactly I asking why the 54.7 degree angle is not 90 degrees? I know it is better but why, is it because to improve the isolation?

[a_l_o]

Hi Mustafa,

I looked into the matter and the line does seem straight to me. As straight as a pixel display can display straight lines...

Ok, trolling out. If the material is supposed to be monocrystalline silicon, there you have your answer: the crystal lattice is most densily packed in this direction. The angle is the inevitable result from etching processes to build up the void under your membrane because this plane is etched muched slower than others. Have a look into wafer fabrication if you are further interested in this topic. Hope I could help you out.