Electromigration behaviors and effects of addition elements on the formation of a Bi-rich layer in Sn58Bi-based solders

Xu Zhao, Masumi Saka, Mikio Muraoka, Mitsuo Yamashita, Hiroaki Hokazono

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

This study investigates the electromigration (EM) behaviors and effects of the addition elements on the formation of a Bi-rich layer in Sn58Bi-based solders including Sn58Bi (SB), Sn58Bi0.5Ag (SBA) and Sn58Bi0.5Ag0.1Cu0.07Ni0.01Ge (SBACNG) solders. The EM tests were conducted at a relatively high temperature of 373 K and at a current density of 30 kA/cm2. Although the dominant diffusing atom was Bi, hillocks were formed from Sn more easily than from Bi. The electrical resistance increased in the solder during the current stressing, and the dominant factor was attributed to the formation of a Bi-rich layer. SBACNG solder showed the highest resistance to the formation of a Bi-rich layer, followed by SBA, and then SB solder. The possible addition elements enhancing the resistance of SBACNG solder are Ag, Ni and Ge. The effects of the addition elements are summarized as follows: (1) Ag distributes in the Sn phase as Ag3Sn intermetallic compounds (IMCs) that enhance the mechanical strength of Sn; (2) Ni distribution in Bi as Ni-Bi IMCs stabilizes Bi and suppresses its migration; and (3) Ge may distribute in Bi, stabilizing Bi, or Ge exists at the phase boundaries as a precipitate that inhibits Bi migration.

Original languageEnglish
Pages (from-to)4179-4185
Number of pages7
JournalJournal of Electronic Materials
Volume43
Issue number11
DOIs
Publication statusPublished - 2014 Nov 1

Keywords

  • Bi-rich layer
  • Electromigration
  • Sn58Bi solder
  • microelements

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry

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