A reliability comparison of electroplated and stencil printed flip-chip solder bumps based on UBM related intermetallic compound growth properties

Jing Feng Gong, Guo Wei Xiao, Philip Ching Ho Chan, Ricky S W Lee, Matthew M F Yuen

Research output: Journal article publicationConference articleAcademic researchpeer-review

3 Citations (Scopus)


The effects of UBM microstructures on the IMC growth of electroplated and stencil printed eutectic Sn-Pb solder bumps were investigated. The process parameters and their relations to UBM surface morphology and UBM shear strength have been established. For electroplating process, the plating current density is the dominant factor to control the Cu UBM microstructure. For stencil printing process, the zincation process has significant effect on the Ni UBM surface roughness and grain size. In both processes, the good adhesion of UBM to Al can be obtained in different UBM process conditions. Samples with different UBM microstructures were prepared by two processes and thermal aged at 85°C, 120°C and 150°C. It was observed the Cu UBM surface roughness has larger effect on the IMC growth and solder ball shear strength than Ni UBM surface roughness. The thickness of Cu3Sn and Cu6Sn5 IMC formed depends strongly on the UBM microstructure. However, for Ni/Au UBM, no significant dependence was observed. More likely, the thickness of Au-Ni-Sn IMC near to solder was controlled by the amount of gold and gold diffusion rate in the solder. Shear tests were performed after thermal aging tests and thermal/humidity tests. Different failure modes were analyzed.
Original languageEnglish
Pages (from-to)685-691
Number of pages7
JournalProceedings - Electronic Components and Technology Conference
Publication statusPublished - 17 Jul 2003
Externally publishedYes
Event53rd Electronic Components and Technology Conference 2003 - New Orleans LA, United States
Duration: 27 May 200330 May 2003

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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