Role of Bismuth in Lead-free Systems - All You Need to Know


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Bismuth (Bi), which is introduced either through the supply chain or by design, is becoming an inevitable element in lead-free electronic products. With the deliberation of all relevant parameters, theoretical and practical, Bi plays a “potent” role in electronic solder systems. The proper use of Bi can profoundly benefit the performance and reliability of electronic package and assembly including solder joint performance, tin whisker mitigation, among others. An adequate understanding of the properties and performance parameters of Bi is critical to product reliability.

This webtorial will discuss the relevant aspects of Bi to help dispel misconceptions and to demonstrate performance criteria related to Bi. The goal is to help achieve the desired level of performance and product reliability. Your questions and issues for solutions and discussions are welcome.

1:00pm to 2:30pm Eastern

Presented by: Jennie S. Hwang, Ph.D., H-Technologies Group

Main topics for Part 1:

  • Your issues & concerns related to Bi
  • Bi - characteristics, resources, safety data
  • Bi effects in 63Sn37Pb solder joint
    • Physical properties
    • Mechanical behavior
  • Effects of Bi from component coating and PCB surface finish
    • Dissolving into solder joint
    • Estimation of concentration of Bi in solder joint
    • Effect of compositional change
  • Bi effects in SAC solder joint (SnAgCuBi)
    • Compositional change
    • Stress vs. strain
    • Fatigue behavior
  • Bi effects in other Pb-free alloys (SnCu, SnAg, SnAgIn)
    • Stress vs. strain
    • Fatigue performance

Main topics for Part 2:

  • Historically established Bi-containing electronic solder alloys
    • Pb-containing
    • Pb-free
  • Bi-containing Pb-free solder alloys
    • Melting temperature range
    • Compositional control level
    • Physical, mechanical properties
    • BGA thermal fatigue performance
  • PCB through-hole fillet-lifting vs. Bi
    • Causes
    • Solutions
  • Low temperature BiPbSn phase
    • Presence or absence
    • Thermograms
    • Detectable or non-detectable effects
    • General guidelines
  • Design limit in Pb-free solder joints vs. solder joint reliability
  • Concluding points

Who Should Attend:

The webtorial provides a working knowledge to all who are involved with or interested in solder joint reliability and system integrity with and without the presence of Bi and related issues in electronic packages and assemblies including designers, engineers, researchers, managers and business decision makers; also is designed for those who desire the broad-based information on the subject.


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