Thermal Characterization of Multi-Layer Graphene Heat Spreader by Pt/Cu/Ti Micro-Coil

Hotspot cooling by heat spreader is essential to avoid reliability issues of the power electronic devices. Herein, the evaluation of the heat spreading capability of mono- and multi-layer graphene using a Pt/Cu/Ti micro-coil heater-thermometer is reported. Monolayer graphene is grown and transferred onto the test structure which consists of micro-coil, pads, and heat sinks. The temperature coefficient of resistance of the bare coil is around 0.0087 degrees C-1. During Joule heating, the bare structure dissipates heat from the coil mainly via stage. Deposited graphene helps carry heat from the coil to the peripheral heat sinks. In transient-state Joule heating, graphene reduced all stage, coil, and hotspot temperatures. However, stage temperature cannot be reduced during steady-state Joule heating. The thickening of the graphene layer did improve the heat dissipation from the coil. The optimum number of layers is suggested to be 3-layers graphene with a hotspot reduction from 5.86 degrees C W-1 down to 4.97 degrees C W-1. More than 3-layers result in a slight increase in hotspot temperature due to heat accumulation within the films. Findings in this work give insight into thermal management strategies in high-temperature power electronics.