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Transient liquid bonding (TLP). TLP overview. Also called Transient liquid phase diffusion bonding . Liquid phase is temporary – in the end an alloy is formed. TLP process in 4 steps. To create the bond, 2 materials with different melting points are needed.
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TLP overview • Also called Transientliquid phase diffusion bonding. • Liquid phase is temporary – in the end an alloy is formed. TLP process in 4 steps
To create the bond, 2 materials with different melting points are needed. • Ni/Sn are the most common • Re-melting temperature of the resulting alloy is higher than the bonding temperature
Features • Provided both mechanical and electrical connection, in separate and multiple areas if needed • Liquid-proof sealing • Similar advantages to eutectic bonding but lower temperatures are needed • Useful for MEMS and power devices
Pros and cons + Relatively low processing temperature + High re-melting temperature allows sequential stacking + Ni and Sn relatively cheap + Contamination with small particles not a problem +/- Electrically and thermally conductive bond • Diffusion-based process – slow • Formation of voids possible • May result in metal ion contamination
TLP example: Cooling system for power devices Sang Won Yoon et al: Reliable and repeatable bonding technology for high temperature automotive power modules for electrified vehiclesJ. Micromech. Microeng. 23 (2013) 015017
Future outlook • TLP with ceramic materials (Aluminium and boron oxide) • Low materials cost • Ultrasonic bonding • Rapid heating by applying ultrasonic waves