Improvement on thermal fatigue properties of Sn-1.2Ag-0.5Cu flip chip interconnects by nickel addition

Shinichi Terashima, Yoshiharu Kariya, Masamoto Tanaka

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

The thermal fatigue properties of Sn-1.2Ag-0.5Cu (in mass%) flip chip interconnect were improved by a small amount of nickel addition. The thermal fatigue resistance of Sn-xAg-0.5Cu flip chip interconnects was enhanced by addition of 0.05 mass%Ni, and Sn-1.2Ag-0.5Cu-0.05Ni had longer thermal fatigue life than Sn-1.2Ag-0.5Cu. Cracks developed near solder/chip interface for all the bumps tested. This crack propagation is mainly governed by the nature of the solders themselves because a strain concentrated area was similar for all the tested alloys independent of the chemical contents. From the microstructural observation, fracture in Sn-1.2Ag-0.5Cu-0.05Ni due to thermal strain was a mixed mode, both transgranular and intergranular. From SEM and TEM analyses, fine Ag3Sn and (Cu,Ni)6Sn5 formed network around Sn grains in the initial microstructure of Sn-1.2Ag-0.5Cu-0.05Ni solder. Sn-1.2Ag-0.5Cu-0.05Ni solder joint suppressed coarsening of Sn grains even after thermal fatigue test. Namely, thermal fatigue properties of the Sn-1.2Ag-0.5Cu-0.05Ni solder joint is correlated to its microstructure, and the joint had longer fatigue life in spite of its lower silver content of 1.2 mass% due to both fine Sn matrix in the initial state and suppression of Sn grain coarsening even after thermal fatigue test.

Original languageEnglish
Pages (from-to)673-680
Number of pages8
JournalMaterials Transactions
Volume45
Issue number3
Publication statusPublished - 2004 Mar
Externally publishedYes

Fingerprint

thermal fatigue
Thermal fatigue
Nickel
solders
Soldering alloys
chips
nickel
fatigue tests
fatigue life
Fatigue of materials
Coarsening
microstructure
Microstructure
crack propagation
Silver
Crack propagation
cracks
silver
retarding
Transmission electron microscopy

Keywords

  • Crack propagation
  • Flip chip
  • Lead-free
  • Microjoining
  • Microstructure
  • Nickel
  • Reliability
  • Silver
  • Solder
  • Thermal fatigue

ASJC Scopus subject areas

  • Materials Science(all)
  • Metals and Alloys

Cite this

Improvement on thermal fatigue properties of Sn-1.2Ag-0.5Cu flip chip interconnects by nickel addition. / Terashima, Shinichi; Kariya, Yoshiharu; Tanaka, Masamoto.

In: Materials Transactions, Vol. 45, No. 3, 03.2004, p. 673-680.

Research output: Contribution to journalArticle

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