Fabrication of Cu@Sn TLPS joint for high temperature power electronics application

Area of Science:

• Materials Science
• Electrical Engineering
• Solid-State Physics

Background:

• High-temperature power electronics require robust interconnects capable of withstanding extreme thermal conditions.
• Traditional interconnects often fail under high-temperature aging and thermal cycling.
• Copper-tin (Cu/Sn) systems are widely used, but enhancing their high-temperature performance remains a challenge.

Purpose of the Study:

• To fabricate and characterize a novel Cu@Sn core-shell composite joint using transient liquid phase sintering (TLPS) for high-temperature power electronics.
• To evaluate the high-temperature mechanical, electrical, and thermal properties of the fabricated Cu@Sn TLPS joint.
• To compare the performance of the Cu@Sn TLPS joint with pure Cu3Sn and other Cu/Sn TLPS joints.

Main Methods:

• Fabrication of Cu@Sn core-shell composite powder via methylate electroplating.
• Preparation of a preformed sheet from the composite powder.
• Reflow processing of the preform under controlled temperature (250–280 °C) and low pressure (0.1 × 10⁻³ MPa).
• Characterization of joint microstructure, shear strength, Young's modulus, hardness, electrical resistivity, and thermal conductivity, including aging tests at 400 °C for 1000 h.

Main Results:

• The Cu@Sn TLPS joint successfully withstood temperatures up to 600 °C, with Sn transforming to Cu₃Sn surrounding residual Cu particles.
• The joint exhibited a high shear strength of no less than 48 MPa after aging at 400 °C for 1000 h.
• Young's modulus (98.35 GPa) and hardness (2.62 GPa) were lower than pure Cu₃Sn, while electrical resistivity (5.1 μΩ cm) and thermal conductivity (148 W m⁻¹ K⁻¹) were superior.
• Performance metrics surpassed those of pure Cu₃Sn and other Cu/Sn TLPS joints.

Conclusions:

• The developed Cu@Sn TLPS joint offers a promising interconnect solution for high-temperature power electronics due to its excellent high-temperature stability and mechanical integrity.
• The optimized microstructure and material composition contribute to superior thermal and electrical properties compared to conventional Cu/Sn systems.
• This technology facilitates high power density modules by providing reliable, high-performance interconnects under extreme conditions.