Application of TLP(Transient Liquid Phase) bonding method to the high Tm lead-free solder

J. S. Lee, W. H. Bang, J. P. Jung, K. H. Oh

Research output: Contribution to journalConference articlepeer-review

7 Scopus citations


TLP method was applied to the lead free soldering process; Sn-3.5Ag core solder (Tm of 221°C) / Sn-Bi coating layer (Tm of 139°C at eutectic) was reflowed on UBM pad. Sn-Bi was formed by electroplating method at current range of 2-6A/dm2, which had varied the coating layer composition from 96wt% to 28wt% Bi. Specimens were reflowed on copper pad at temperature range of 200 and 220°C, and then interface reaction was examined. It was claimed that high Bi adding in the plated layer improved the wetting performance on Cu. Even at the reflow temperature of 200°C, SEM observation revealed well-defined interface junctions between solder and copper pad, i.e. nucleation and growth of CuxSn intermetallic compound. After heating for 5min at 220°C, Bi was resolved into Sn-3.5Ag core solder and completely homogenized, which is favorable from the viewpoint of long term fatigue reliability.

Original languageEnglish
Pages (from-to)1869-1872
Number of pages4
JournalMaterials Science Forum
Issue numberIII
StatePublished - 2005
EventPRICM 5: The Fifth Pacific Rim International Conference on Advanced Materials and Processing - Beijing, China
Duration: 2 Nov 20045 Nov 2004


  • Electroplating
  • Reflow
  • Soldering
  • TLP(Transient Liquid Phase) method


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