Controlling Interfacial Exchanges in Liquid Phase Bonding Enables Formation of Strong and Reliable Cu–Sn Soldering for High-Power and Temperature Applications

Abstract

Developing solder joints capable of withstanding high-power density, hightemperature, and significant thermomechanical stress is essential to further develop electronic devices performances. This study demonstrates an effective route of producing dense, robust, and reliable high-temperature Cu-Sn soldering by modifying the interfacial exchange during a transient liquid phase bonding (TLP) process. Our approach relies thus on altering internal phenomena (diffusion and transport of reactive species) rather than classical external TLP bonding parameters (e.g., time, temperature, and pressure). By adding a Cu3Sn coated layer between Cu and Sn before the TLP process, a fast dissolution of Cu in liquid Sn is achieved, altering undesired Cu6Sn5 scallop grains impingement and promoting their uniform growth within the liquid. A bonding and pore formation mechanism of the solder with or not the Cu3Sn coated layer is proposed based on experimental and theoretical analysis. The developed TLP joint possesses a shear stress resistance of more than 80 MPa with a thermal cycle endurance 2 superior to 1200 (-45 to 180 ºC), making it highly reliable compared to a classical solder joint with shear and thermal cycling resistance of 45 MPa and 500, respectively. The developed approaches provide, thus, an easy, affordable, and scalable method of producing hightemperature and durable Cu-Sn joint for high-power module applications.

Comparative Study of the Impurity Effect on SnAgCu and SnZn Solder Joints with Electrodeposited Cu

“…In the soldering process, molten solder reacts with the metallization, resulting in the formation of intermetallic compounds (IMCs) at the joint interfaces [8][9][10]. IMC formation is an indicator of successful joints, like the Cu 6 Sn 5 and Cu 3 Sn phase in Sn-based solder/Cu joints [11,12]. However, the faster growth of IMCs accompanying the formation of Kirkendall voids gives rise to critical reliability issues [13].…”

Robust Cu–Cu Bonding with Multiscale Coralloid Nano-Cu3Sn Paste for High-Power Electronics Packaging

“…Intermetallic compounds (IMCs), which possess high MP, for example, Cu 6 Sn 5 (415 °C) and Cu 3 Sn (676 °C), have been widely investigated in the reaction between the Cu substrate and tin-based solders. − Recently, full-IMC joints, which can be formed at low temperature but can be serviced at high temperature, have been considered to overcome the above-mentioned technological challenges. The full-Cu 6 Sn 5 or full-Cu 3 Sn IMC joints are usually fabricated by eutectic bonding, transient liquid phase (TLP) bonding, and solid–liquid interdiffusion (SLID) bonding technologies. − However, the above bonding techniques may require longer times (for example 120 min, 180 min, and 960 min) to form a thermodynamically stable full-IMC joint.…”