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|Thermal Characterization and Simulation of a fcBGA-H device|
|Keywords: thermal, characterization, modeling|
|In this paper, the thermal performance data of theta jc and theta ja of a flip chip device with heat spreader, fcBGA-H, are measured and compared with simulation data. A transient measurement method is used to obtain the temperature responses of the diodes, as a function of time, at different locations on the die. The structure functions of the diodes are measured, and based on the structure functions, the theta ja and jc are calculated. With this experimental setup, there is no need to use thermocouples for temperature measurements. The traditional hole drilled to install a thermocouple and the thermocouple itself can change the package configuration and heat dissipation path, and, therefore, impact the accuracy of the measurements The current experiment further measures the non-uniform distribution of the temperatures of the die, and compares the structure functions at different locations to predict the magnitudes of the powering. These structure functions reflect the thermal behavior at their particular positions. By manipulating the powering currents into the diodes, the curves of structure functions are shifted and based on the shifting, the real power distribution of the device is estimated. The novel approach of calculating the power distribution may be important when the power distribution becomes very complicated especially for the high power CPU which has multi-cores or multi-cells for their power distribution on the cells could be overlapped with each other. Besides the experiments, a computer thermal simulation is conducted to correlate with the experimental data. The theta ja and jc are simulated with appropriate boundary conditions. For theta jc, two kinds of boundary conditions are used, one is a fixed temperature on top of the lid, and the other one considers the fluid flowing behavior inside the cold plate. The simulation and experimental data are compared to verify the prediction.|
|Eric Ouyang, Staff