thermoconductive material pressure

[fabrizio_brescia]

Good morning, we're supposed to have this problem, but we can't find an immediate solution.
I put it so that someone can direct us or to the solution or to the methods to find it.
we have a printed circuit about 75mm x 25mm thickness 1mm with 6 fixing screws to a heat sink. seserve I can also attach the step file.
between heat sink and circuit is put a thermoconductive material whose thermal resistance is function of pressure.
the data speak of 100,300 and 500 kpascal, the goal is to determine the newtons with which I have to tighten the 6 screws m2.5 per head rigged to get more or less these compression forces.
definitely the pressure will not be constant (the screws are placed in the corners and in the middle, always aligned on the long side, because in the center there is a zone of 10mm in which there are components.

thanks for the help
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[luigi.paiano]

I would give a precarious fi equal to the pressure necessary for the whole divided area six. clearly if the screws do not have to endure other stresses. But I think it is essential to do a fem analysis to understand what happens. if you attach the step file maybe we can see better

 

[fabrizio_brescia]

here is the step model.
It's simple, the material is aluminum, I let you decide the alloy, I don't need a very powerful answer.

Thank you.
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