Chin-Chi Hsu

Pool boiling of nanoparticle-modified surface with interlaced wettability

This study investigated the pool boiling heat transfer under heating surfaces with various interlaced wettability. Nano-silica particles were used as the coating element to vary the interlaced wettability of the surface. The experimental results revealed that when the wettability of a surface is uniform, the critical heat flux increases with the more wettable surface; however, when the wettability of a surface is modified interlacedly, regardless of whether the modified region becomes more hydrophilic or hydrophobic, the critical heat flux is consistently higher than that of the isotropic surface. In addition, this study observed that critical heat flux was higher when the contact angle difference between the plain surface and the modified region was smaller.

Influence of surface temperature and wettability on droplet evaporation

The evaporation characteristics of sessile water droplets on various wettability substrates (hydrophilic, hydrophobic, and mixed wettability surfaces) were experimentally investigated in this study. Placing droplets on a regulated superheated surface led to rapid vapor bubble formation. The droplet parameters, such as the contact angle and volume evolution over evaporation time, were experimentally measured. The results revealed that surface wettability plays a critical role not only in vapor bubble dynamics but also in evaporation.

Hybrid thermal solution for 3D-ICs: Using thermal TSVs with placement algorithm for stress relieving structures

Stacking die technology using through-silicon-via (TSV) technology has attracted a lot of attention due to various advantages in performance and integration. However, a high temperature environment during the fabrication process of TSV leads to uncontrollable thermal expansion, which then causes a serious reliability problem, the thermal mechanical problem. This problem can result in deformation or mechanical damage to the dies; therefore, it must be resolved. Unlike previous works applying novel components which are not in the standard CMOS process and thus potentially very expensive, this paper proposes to use package process compatible component, micro bumps, to relax the thermal mechanical stress. In addition, we present an efficient algorithm to place micro bumps in appropriate positions to minimize the total number of micro bumps needed. Our simulated results show that significant reduction on the maximum stress can be achieved. Not only the proposed design can lower the maximum temperature of the hotspot, but improve the thermal uniformity of the test chip. Finally, the infrared radiation thermal images are employed for monitoring the temperature of the virtual cores and that of the hybrid thermal solution. The experimental results show that one of proposed design provides excellent capability for enhancement of thermal conduction.