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Old April 21, 2009, 03:16 PM
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3 of 7 3 of 7 is offline
Join Date: Nov 2008
Location: Nanaimo BC
Posts: 919

Originally Posted by ICD7 View Post
3 of 7 - post 183

Your point is understood and you are correct on that I believe. Taking another look, if there was was flex it would be highly coincidental that it would be only in the copper area.

So why only in the copper area is it different? Thermal Expansion Coefficients between the copper and aluminum?

or assuming no difference in surface quality between the aluminum and copper could it be the thermal gradient across the sink under load affects how the paste adheres when it is separated? Very interesting effect,at least to me anyway.

The application looks fine to me, it may be the camera angle but the application is slightly off center hence the tendency of the paste would be to flow to the closest edge or path of least resistance.

Likely that the exposed area was not making contact with the sink/IHS separated by at least the particle thickness in that one area. Not sure whether it would make that much difference though in thermal result as the center and top section of the IHS are well covered.
It wasn't the camera angle. Even though I was very careful to place the HS on squarely, one time the pattern was definately towards the bottom and the second time it was more towards the top.
I believe the 2 screw system of tightening the HS allows it to squish the paste towards one side or the other before there is enough clamping force to pull it down squarely.
My bet is a line of paste perpendicular to the screws would do a better job.
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