Hierarchically Structured Laser-Induced Graphene for Enhanced Boiling on Flexible Substrates.

Area of Science:

• Materials Science
• Thermal Engineering
• Electronics Packaging

Background:

• High-power flexible electronics require advanced thermal management to prevent overheating and skin burns.
• Current heat dissipation methods struggle with the complexity and flexibility demands of these devices.
• Polymer substrates commonly used in flexible electronics present challenges for efficient heat removal.

Purpose of the Study:

• To investigate the heat transfer characteristics of laser-induced graphene (LIG) on flexible polyimide substrates.
• To evaluate the potential of LIG as an effective heat dissipation solution for flexible electronics.
• To explore methods for further enhancing LIG's thermal performance.

Main Methods:

• Laser direct writing was used to create patterned LIG (200 μm mesh spacing) on polyimide films.
• Pool boiling experiments were conducted using FC-72 as the working fluid.
• LIG surfaces were modified by separating liquid supply and vapor escape passages.

Main Results:

• LIG surfaces demonstrated significantly enhanced heat transfer characteristics compared to pristine polyimide.
• The critical heat flux increased 2- to 3-fold, reaching 33.6 W/cm².
• The heat transfer coefficient improved 2- to 3-fold, reaching 7.6 kW/(m²·K).

Conclusions:

• Laser-induced graphene is a highly effective material for enhancing heat dissipation in flexible electronics.
• The porous and bendable nature of LIG makes it suitable for flexible substrates.
• Optimized LIG structures, including separated fluid pathways, further improve thermal management capabilities.