There are a lot of unknown variables in your question. But, it might be save
to generalize.

There is a difference in performance. If the design really pushes things you
may not be able to use the thermal pads. The thermal compound, given ideal
conditions will perform better. But, practically, the thermal pads work very
well. We found for one design evaluation, given all the variables in
production materials and process methods, the pads gave us much less
variation in performance and worked better because of it.

In another evaluation, where the design operated closer to the edge, we
could not use the thermal pads.

Imagine two bell curves, one with higher Cp but lower average performance
than the other, and you have the results of my experience with thermal
compound and thermal pads.

In other words . . . Cp versus Cpk


-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Eric Kalgren
Sent: Tuesday, January 11, 2005 9:04 AM
To: [log in to unmask]
Subject: [TN] Thermal Compound vs. Sil-Pads


Good morning everyone!  We have an issue that has come up dealing with
sinking heat out of a resistor on one of our antennas.  We are currently
using thermal compound (Wakefield 120) between the resistor and the heat
sink.  However, we are ramping production up to full tilt and we'd like
to use a precut thermal pad (like a sil-pad but a different brand name)
to save some time on assembly.  Have any of you used these in heat
sinking. How do they compare to the goop that is heat sink compound?  It
is a 150W flange mount resistor by Florida RF labs spec'ed for a max
temp of 150*C and a frequency range of DC-2GHz.



Thanks in advance for your help



Eric Kalgren

Manufacturing Engineer

Atlantic Microwave

Phone: 978-779-7062

Fax:     978-779-0101




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