Morphology and Intermetallics Study of (Sn-8Zn-3Bi)-1Ag Solder under Liquid-State Aging

Abstract:

This study investigated the effect of Ag addition on the morphology and growth rate of Cu₅Zn₈, Cu₆Sn₅ and Cu₃Sn intermetallics in the Sn-8Zn-3Bi solder. The solder was prepared by mixing 1wt% of Ag into 99wt% of Sn-8Zn-3Bi solder. The intermetallics were formed by liquid-state aging, whereby the solders were reacted on Cu substrate above the melting temperature of the solder. The reflow was done at 250°C and 270°C at various soldering times. A scanning electron microscope (SEM) was used to observe the morphology of the intermetallic phase and energy dispersive X-ray (EDX) was used to identify the elemental composition. The Sn-8Zn-3Bi solder reacting with Cu substrate formed a single Cu₅Zn₈ intermetallic layer with a flat structure. On the other hand, the reaction between (Sn-8Zn-3Bi)-1Ag solder and Cu substrate produces Cu₆Sn₅ intermetallic. This Cu₆Sn₅ intermetallic has a scallop structure. As the soldering time increases, a second layer, identified as Cu₃Sn starts to grow. The thickness of the intermetallics increases with aging temperatures and time. The addition of Ag into the Sn-8Zn-3Bi solder has significantly suppressed the formation of Cu₅Zn₈ intermetallic and promoted the growth of Cu₆Sn₅ intermetallic.

• Periodical: Advanced Materials Research (Volume 620)
• Pages: 273-277
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.620.273
• Online since: December 2012
• Authors: Nor Aishah Jasli, Hamidi Abd Hamid, Ramani Mayappan
• Keywords: Cu₅Zn₈, Cu₆Sn₅ , Growth Rate, Intermetallic, Lead-Free Solder

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