John D. Schwarzkopf

A Low Profile Thermal Management Device for High Power Processors Using Enhanced Flow Boiling Techniques and Perfluorocarbon Fluids

It is advantageous to the electronic industry to remove in excess of 150W from a processor die with a case-to-ambient thermal resistance < 0.2 ° C/W. Although this is achievable with air cooled thermal solutions, the form factor is unwieldy and as the ambient temperature rises, the processor throttles the performance. Alternatively, thermal solutions containing water are trivial to implement but potential leaks can pose a threat to the electronic suite. The present solution is non-trivial; it utilizes a dielectric perfluorocarbon fluid (PF5050) and a combination of spray cooling and mini-channel flow boiling techniques with a particular focus on superficial quality at the onset of the channels. The idea behind mixing the two techniques is to augment the heat transfer coefficient by driving the fluid into an annular state upon entry of the mini-channels while retaining a low profile package. A macro-channel boiling heat transfer correlation was used and results show that it predicts the average surface temperature to within 10% of the experimental data. Quasi-one-dimensional numerical models were developed to predict vapor entrainment and two-phase pressure drop. Experimental results show that in excess of 250W can be removed from a 1.24cm × 1.24cm die without removing the integrated heat sink (IHS), with a case-to-ambient thermal resistance of <0.2° C/W at 150W. The packaged size is 5.6cm long by 3.1cm wide by 1.6cm tall, thus allowing the end user to adapt the technology into blade style or 1U style servers with low risk.Copyright