Authors:

Kyle Wieg

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About Paper:

High Pb solders (95Pb-5Sn, 92.5Pb-5Sn-2.5Ag) are most common solders for operating temperatures above 200 degrees Celsius for SiC or GaN-based power electronics. A main challenge in developing Pb-free solder or transient liquid phase bonding (TLP) technique is comparable or superior mechanical and thermal properties to Pb-based solders. Further, a drop-in solution of an alternative to Pb-based solder alloy is preferred that can be reflowed on the existing die and substrate metallization without significant changes to the established manufacturing processes. Bismuth-based solder alloys are notably promising in this sector as viable substitutes for lead-based solder, offering favorable properties and reduced environmental impact. These alloys demonstrate excellent thermal and electrical conductivity, low toxicity, and improved mechanical properties, making them suitable for various electronic applications. However, a significant drawback of bismuth-based solder alloys lies in their wettability issues, particularly when it comes to commonly used substrate materials like copper and nickel. Poor wetting behavior can result in insufficient adhesion and compromised joint integrity, leading to unreliable solder connections and increased failure rates. Overcoming this challenge requires ongoing research and development efforts to enhance the wetting behavior, ensuring reliable solder connections and wider adoption of bismuth-based solder alloys in the electronics industry. Here we compare the morphology and mechanical properties of 58Bi-42Sn and 95Bi-5Sn alloys, which will lead to customizing the properties of these solder materials through alterations in their composition and structural dimensionality.

Source:

Purdue University / 2023

Topics:

No topics listed

Co-authors:

Kyle Wieg