Journal of Materials Science

, Volume 48, Issue 6, pp 2724–2732 | Cite as

Microstructural variation and high-speed impact responses of Sn–3.0Ag–0.5Cu/ENEPIG solder joints with ultra-thin Ni–P deposit

  • Cheng-Ying Ho
  • Jenq-Gong Duh
  • Chih-Wei Lin
  • Chun-Jen Lin
  • Yu-Hui Wu
  • Huei-Cheng Hong
  • Te-Hui Wang


Electroless Ni–P/electroless Pd/immersion Au (ENEPIG) with ultra-thin Ni–P deposit serve as a potential replacement of traditional ENEPIG surface finish because of its superior electrical performance in flip chip solder joints interconnection. However, the interfacial reaction and mechanical reliability of solder joints in ENEPIG with ultra-thin Ni–P layer is not yet well evaluated. In this study, we investigated the characteristic microstructure of interfacial intermetallic compounds and high-speed impact responses of Sn–3.0Ag–0.5Cu/ENEPIG attachments with 4.8, 0.3, and 0.05 μm Ni–P deposit. ENEPIG with Ni–P layer of 0.3 μm exhibited the eutectic structure dispreading in the solder alloys and layer-type P-rich IMCs at solder/metallization interface, while there was (Cu,Ni)6Sn5 precipitation in the solder but no P-rich IMCs layer formed in ENEPIG with 0.05 μm Ni–P layer. Slower interfacial reaction rate in ENEPIG with 0.3 μm Ni–P layer was attributed to the effect of electroless Ni–P diffusion barrier layer, which would further provide better impact resistivity than that of ENEPIG with 0.05 μm Ni–P deposit. Moreover, breach in P-rich IMCs and underneath (Cu,Ni)6Sn5 patch were observed in ENEPIG with 0.3 μm Ni–P layer. The growth mechanism was closely related to the Ni diffusion from surface finish and element redistribution.


Solder Joint Impact Toughness Solder Alloy IMCs Layer Interfacial IMCs 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



The authors would like to acknowledge Kinsus Interconnect Technology Co. for the materials supplied. This study was financially supported by Kinsus Interconnect Technology Co. and National Science Council, Taiwan, under Contract No. NSC-97-2221-E-007-021-MY3.


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Copyright information

© Springer Science+Business Media New York 2012

Authors and Affiliations

  • Cheng-Ying Ho
    • 1
  • Jenq-Gong Duh
    • 1
  • Chih-Wei Lin
    • 2
  • Chun-Jen Lin
    • 2
  • Yu-Hui Wu
    • 2
  • Huei-Cheng Hong
    • 2
  • Te-Hui Wang
    • 2
  1. 1.Department of Materials Science and EngineeringNational Tsing Hua UniversityHsinchuTaiwan
  2. 2.Kinsus Interconnect Technology CorporationTaoyuanTaiwan

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