5. Thermal Diagnostics and Cooling Solutions for IC
Packaging
Dr. Katsuo Kurabayashi, Roy Zeighami, and Peng Zhou
The increasing integration of electronic systems is leading to challenges for the thermal design of packaging. This project addresses these challenges through two activities, the first of which is the development and assessment of high-performance heat-sinking solutions. The MTMC lab plays a leading role in a recently-awarded DARPA project ($3.1 Million, 1999-2001), which will integrate electrokinetic pumping technology with two-phase micro-channel and jet heat exchangers. This activity will closely link the MTMC lab to microfluidics and micromachining research in the groups of Santiago and Kenny at Stanford. The resulting devices promise to remove more than 200W from a single chip with less than 1W of pumping power. Figure 1 depicts the charge distribution near the wall of the capillary, which allows an applied electric field to pump the liquid.
An example of pase work on advanced cooling technology is work on diamond
microchannel arrays for laser-diodes, which use the high thermal conductivity
of the diamond to increase the efficiency of the channel-wall fins.
The diamond also reduces the spreading thermal resistance from localized
heat sources at the surface of the semiconducting device. The second
activity is motivated by the fact that engineers at semiconductor firms
are investing more time into finite-element thermal-conduction simulations
of packaging. The accuracy of these simulations is impeded at present
by the lack of data for the thermal transport properties of the materials
and interfaces in electronic systems, as well as by the lack of tools available
for accurate measurement of these properties. Also important is the
lack of tools for measurement of the thermomechanical strain fields.
These diagnostic techniques should provide micrometer-scale spatial resolution
and function under high-stress conditions including moisture exposure,
thermal cycling, and electrical overstress. Project
1 described laser-reflectance thermometry activities performed over
a wide range of spatial and temporal resolution down to 1 ns and 50 nm.
This photothermal mapping capability is being leveraged to precisely resolve
thermal resistance contributions in die attachment and in cross-sectioned
flip-trip structures. Because the photothermal techniques do not
require physical contact, they are readily applied under stressing conditions
including moisture exposure and temperature cycling.
Collaboration
Components Research, Intel
Groups of Professors Santiago and Kenny, Mechanical Engineering Department,
Stanford University
Recent Publications
Kurabayashi, K., and Goodson, K.E., 1998, "Precision Measurement and Mapping of Die-Attach Thermal Resistance," accepted by the IEEE Transactions on Components, Packaging, and Manufacturing Technology, Part B: Advanced Packaging, in press.
Goodson, K.E., Kurabayashi, K., and Pease, R.F.W., 1997, "Improved Heat Sinking for Laser Diode Arrays using Microchannels in CVD Diamond," IEEE Transactions on Components, Packaging, and Manufacturing Technology, Part B: Advanced Packaging, Vol. 20, pp. 104-109.
Zhou, P. and Goodson, K.W., 1999, "Diagnostics of FLIP-CHIP/BGA Structures using Phase-Shifting Speckle-Pattern Interferometry," Proceeding of InterPAK, '99, Maui, Hawaii, June 13-19.
Sponsorship
DARPA HERETIC Program
SRC Contract 98-PJ-357