Learn about ultra-low thermal resistance structural heat spreaders built with the OHP technology to improve the thermal management of high heat flux devices. The OHP heat spreaders presented herein have a copper or aluminum envelope material of nominal size 3” x 1.5” ranging in thickness from 0.150 – 0.190”. Tested in high power arrangement up to 330 W heat input (nominal heat flux of 256 W/cm2), with predicted operation up to 600 W via OHP limits modeling.
At high power inputs OHP heat spreaders demonstrated thermal resistances 40% lower than that of an equivalent solid copper spreader. Under a separate demonstration effort, OHP heat spreaders were tested in high heat flux arrangements up to 1,550 W/cm2 with two heat input regions totaling an area of 0.037 cm2 and a total heat load of 56W and a peak flux of 1,800 W/cm2 with no sign of performance degradation.
ThermAvant Technologies has also refined and verified limits modeling capabilities with these high flux thermal ground plane OHPs. In 2018 the process further refined the OHP limits model and is now able to predict the onset of nucleate boiling in OHPs’ microchannels which in turn correlates to the characteristic drop in thermal resistance, or increase in conductance, of a well-functioning OHP. Of particular focus was experimentally verifying the previously developed start-up limit and demonstrating that the swept length limit’s non-applicability to this form factor. This “StartUp” limit is critical to predicting the lower temperature and lower power operational bounds of OHPs.