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

Abstract

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 °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 °C W−1 down to 4.97 °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.