Thermal Management – Paul Wu's Blog

Colorless PI

Polyimide (PI) film has been broadly used in industries due to its high mechanical strength, thermal stability, low coefficient of expansion (CTE), etc.

Al Vs Cu

Traditionally, IC interconnects formed from Al; however due to scaling and performances needs, Copper is gradually replacing Aluminum.

A method to reduce nodules on ED copper foil

ED copper foil is broadly used in Li-ion battery and printed circuit boards in electronics industry. However, nodules are commonly observed on the surface of ED copper foil made through a conventional electro-deposition method. Patent of US 9,562.298 B2 teaches a new way to reduce the number of the nodules on the surface.

Liquid metal

For liquid metals, people may immediately think of mercury; in fact there are several other metals with melting point close to room temperature in addition to Mercury (Hg, MP=−38.8 °C, e.g. Caesium(Cs, MP=28.5 °C, Rubidium (Rb, MP=39 °C, Francium (Fr, estimated MP= at 27 °C), and Gallium (Ga, MP=30 °C). However, due to the issues of radioactivity, vapor pressure, and toxicity, etc, the practical liquid metal is typically Ga based eutectic alloy with melting point less than that of Ga.

Accuracy of Steady State Thermal conductivity measurement

The steady state method is commonly adopted to measure thermal resistance and conductivity of thermal interface materials or TIMs. A heat flow through the TIM is generated and the temperature gradient across the TIM is measured, and the thermal resistance or conductivity can be calculated through the procedure defined by ASTM standard ASTM D5470.

Super cooling technology: VC & graphene

There are two ways to combine Vapor Chamber and Graphene and deliver super cooling effects:

Heat Pipes & Vapor Chambers

Due to limited space in consumer electronics, traditional heat sinks and fans become irrelevant anymore. Besides, thin film graphite sheets, from 20-100um thick, gradually phase out as well due to limited thermal dissipation capability and weak mechanic performances, particularly poor layer to layer cohesion. Meanwhile slim heat pipes and vapor chambers are taking the momentum.