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A single substrate intended for a 3-dimensional (3D) edge-cooled multichip module (MCM) has been built and thermally tested. The substrate, with dimensions 1.9 in. by 2 in., is mounted in a fluid cooled block at one end. To test this cooling architecture and verify the accuracy of thermal models, we constructed thermal test modules using alumina (Al/sub 2/O/sub 3/), aluminum nitride (AIN), and CVD diamond substrate materials. Each module was populated with an array of 16 Sandia ATC03 test chips with resistive heaters and temperature sensing diode thermometers. Comparative measurements of the 3 substrates were made in which the top row of 4 die were heated at 5 W each for a total of 20 W. The maximum temperature differences between the heated die and the interface with the cold chuck, /spl Delta/T/sub JS/, were 24, 126, and 265/spl deg/C for diamond, AIN and Al/sub 2/O/sub 3/, respectively. Measurements on the diamond thermal test module, uniformly heated at a total power of 45 W, gave a measured substrate-to-sink temperature of /spl Delta/T /spl AP/ 20/spl deg/C. An extrapolation of our experimental data indicates that the diamond edge-cooled substrate could dissipate a total power /spl AP/ 192 W for a maximum junction-to-ambient temperature of /spl Delta/T/sub JA/ /spl AP/ 124/spl deg/C. If multiple substrates were 3 mounted in the fluid cooled block, spaced 0.075 in. apart, the volumetric power density would be about 850 W/in/sup 3/. |
