Calibration Methodology for Interposing Liquid Coolants for Infrared Thermography of Microprocessors

Hom, L., Durieux, A., Miler, J., Asheghi, M., Ramani, K., Goodson, K.E. "Calibration Methodology for Interposing Liquid Coolants for Infrared Thermography of Microprocessors". IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITHERM) 2012, May 30 - June 1, San Diego, CA

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There have been unprecedented temperature non-uniformities reported in conventional 2D- and emerging 3D-packaged multi-core microprocessors. Therefore, techniques for spatially resolving chip power and temperature profiles in fully operational chips are needed to improve circuit design and enable optimal cooling solutions. This paper presents a high-resolution, infrared (IR) thermography technique for microprocessors operating at fully-operational power levels. A custom, microfluidic heat sink with an IR-transparent working fluid (0.75 LPM) is manufactured to cool an instrumented test chip while permitting optical access for IR thermal imaging. A detailed system calibration is conducted to account for the temperature-dependent optical properties of the chip and heat sink. It is concluded that the IR imaging can be conducted with ~ 0.1 °C error over the temperature range of 45-90 °C if the fluid plenum height is less than 500 μm. For a 2 mm channel, the error can be as high as 43°C due to strong signal attenuation in the fluid.

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