Demonstration of Ni-free Surface Finishing with IGEPIG for Solid-State Diffusion Bonding on Ultra-fine Pitch Chip-on-Film (COF)

Research output: Chapters, Conference Papers, Creative and Literary Works (RGC: 12, 32, 41, 45)32_Refereed conference paper (with ISBN/ISSN)

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Author(s)

  • Kelvin P. L. Pun
  • Jason Rotanson
  • Navdeep S. Dhaka
  • Chee-Wah Cheung
  • Alan H. S. Chan

Detail(s)

Original languageEnglish
Title of host publication2018 IEEE 20th Electronics Packaging Technology Conference (EPTC)
PublisherIEEE
Pages924-931
ISBN (Electronic)978-1-5386-7668-4
Publication statusPublished - Dec 2018

Publication series

NameElectronics Packaging Technology Conference Proceedings

Conference

Title20th IEEE Electronics Packaging Technology Conference (EPTC)
PlaceSingapore
CitySingapore
Period4 - 7 December 2018

Abstract

This paper demonstrates the latest ultra-fine pitch scalability of off-chip IC assembly on an 18 um pitch chip-on film (COF) package fabricated by novel fully additive process (FAP) with Ni-free surface finish plating, immersion ALL/electroless Pd/ immersion Au (IGEPIG). The COF assembled with Au-Au diffusion bonding method is evaluated in terms of electrical and mechanical performance. Comparison is made with various finishes including Electrolytic Ni/Au and electroless Ni/ electroless Pd/ immersion Au (ENEPIG). Excellent alignment with sufficient contact area is achieved even on such narrow traces. The substrate fabricated by FAP possess desirable trace profile suitable for fine pitch bonding. With different finishing, it is seen that surface roughness is the main contributing factor that interrupt diffusion and creep process in forming void on the joint interface while the elastic plastic properties of the material construction and tri-layer thickness affect the deformation of the interconnect structure. Correlations between the surface finish and the Au-Au solid-state diffusion bonding on the COF is established. In terms of long term reliability, all finishes show stable contact resistance below 30 m Omega with no open joint on the daisy chain connectivity after high temperature humidity storage at 85 degrees C/85% RH (1000 hours) and air-to-air thermal shock test at 125 degrees C/-55 degrees C (1000 cycles).

Research Area(s)

  • Au-Au solid-state diffusion bonding, Fine-pitch COF, Fully additive process, Ni-free surface finish, GOLD

Citation Format(s)

Demonstration of Ni-free Surface Finishing with IGEPIG for Solid-State Diffusion Bonding on Ultra-fine Pitch Chip-on-Film (COF). / Pun, Kelvin P. L.; Rotanson, Jason; Dhaka, Navdeep S.; Cheung, Chee-Wah; Chan, Alan H. S.

2018 IEEE 20th Electronics Packaging Technology Conference (EPTC). IEEE, 2018. p. 924-931 (Electronics Packaging Technology Conference Proceedings).

Research output: Chapters, Conference Papers, Creative and Literary Works (RGC: 12, 32, 41, 45)32_Refereed conference paper (with ISBN/ISSN)