Enerdyne Solutions makes the Indigo thermal package
it was a competitive analysis of current technologies and was presented at the
International Microelectronics and Packaging Society
(IMAPS) Advanced Thermal Workshop in 2005
the paper from the previous year was
Performance Reliability, and Approaches Using a Low Melt Alloy as a Thermal Interface Material (PDF)
a results summary can be had here
Indigo Thermal Impedance Comparision
but the pertinant passages I thought where
"These differences can be factored out by application of a TTV-to-CPU correction factors"
test rig diagram & proceedure
"small changes in the package dimensions from Oil canning or spherical deformation can be significant, The Coefficients of Thermal Expansion (CET) mismatch between the Flip Chip Pin Grid Array (FCPGA) and the heat spreader lid may cause the Bondline Thickness (TIM1) to change slightly as the package temperature is lowered from the
adhesive glass transition temperature (tg)"
"This small dimensional instability is not normally significant with low performance Thermal Interface Materials (TIMs)"
implying that while care must be exercised in the selection of TIM1\IHS\sealant when taking into consideration oil canning,
the impact on TIM2 is less pronounced do to its lower conductivity and that maintaining an optimal contact between the IHS and heatsink is likely targeted by package designers to a specific temperature range. (observation of the "flatness" of an IHS is really dependent on its temperature) far more than any compression flex, and further that an "optimal target temperature" is unlikely to match "enthusiasts" and especially extreme "coolers" but rather be the median temperature youd see in a server or desktop possessed by the average joe.
further investigation of the papers shows the considerable weight maintaining the seal plays in the reliability of an IHS
by deduction also temperature\thermal cycling dependent