Thermal Management Of Supercomputer Subsystem And Manufacture & Thermo-mechanical Reliability Of 3D-MCM For Wireless Sensor Network

System-level thermal simulation and design optimization for a kind of supercomputersubsystem—chassis was conducted, and a three dimensional multi-chip module (3D-MCM)for wireless sensor network was developed, and furthermore, its thermo-mechanicalreliability was studied.Thermal performance of a supercomputer chassis including 128 ASIC chips wassimulated by CFD (Computational Fluid Dynamics) method. The significant variables suchas the chip arrangement, structure of plate heat sink, clearance spacing of air duct, ambienttemperature etc. are studied and optimized, the optimal values of above parameters arepresented. The experiment results of prototype are coincident with simulation results. Thesignificances of above parameters are studied by using the orthogonal experiment designmethod. Furthermore, the V-shaped curves of the chip temperature vs. fin-pitch andfin-thickness are derived by using the full factorial experiment method, and a thermalresistance model is built to explore the profile and obtain the convective heat-transfercoefficient of the heat sinks. It turns out that the V-shaped profile arises from the jointaction of the thermal conduction and convection of heat sink, which can be attributed to theintricacy of the dependencies of thermal resistances on either fin pitch or thickness. Biotcriterion was revised that Biot criterion is applicable to estimate the Biot Number oflarge-scale plate-fin heat sink, but not applicable for the small-sized one. Finally, theempirical formulas of heat transfer are obtained and the fin-pitch and fin-thickness areoptimized.A new type of 3D-MCM is developed. FCOB, COB, BGA technologies are combined together with 3-D packaging, wire bonding and Flip-chip interconnection technologies arecombined together, and PBGA device and bare die are hybrid-integrated on a multi-layerFR-4 substrate with embedded chip. The thermal behavior of 3D-MCM are simulated andevaluated, which indicated the 3D-MCM designs are reasonable and realizable. The3D-MCM dimensions are equal to only 30% of that of primary 2D package and assemblyefficiency reaches up to 70%. Test result indicated that the electrical performance of3D-MCM is coincident with that of 2D-PCB. The techniques embedding positive deviceinto multi-layer substrate was developed, and the repeated reflow-soldering problem wasalso solved. Thermal cycle test demonstrates that the fatigue life of 3D-MCM are morethan 1500 temperature cycles. The thermal cycle simulation was also conducted by usingfinite element method (FEM) so as to investigate the mechanical characteristics and topredict the fatigue life of 3D-MCM. The simulated fatigue life is coincident with thethermal cycle test. The effects of structure parameters and material parameters on thesolder ball fatigue life were studied in conjunction with FEM and response surface method(RSM).Finally, 3D-MCM warpage was studied by using linear elastic, viscoplastic and largedeformation models. The results turns out that: it is the existence of the cavity in substratethat results in the double-bow warpage and the inflection point of warpage vs. temperaturecurve of substrate; Cavity in the substrate center could make for the decrease of substratewarpage; Proper usage of underfill material could strengthen interconnection of device andsubstrate and could decrease warpage of 3D-MCM, however, the too big CTE of underfillmaterial may incur other new failure models. Moiréfringes test of 3D-MCM validated themodeling and warpage prediction.