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Electronics and Telecommunications Research Institute (한국전자통신연구원)
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Curing Kinetics and Chemorheological Behavior of No-flow Underfill for Sn/In/Bi Solder in Flexible Packaging Applications

  • Eom, Yong-Sung (ICT Material & Components Research Laboratory, ETRI) ;
  • Son, Ji-Hye (ICT Material & Components Research Laboratory, ETRI) ;
  • Bae, Hyun-Cheol (ICT Material & Components Research Laboratory, ETRI) ;
  • Choi, Kwang-Seong (ICT Material & Components Research Laboratory, ETRI) ;
  • Lee, Jin-Ho (ICT Material & Components Research Laboratory, ETRI)
  • Received : 2016.01.27
  • Accepted : 2016.08.18
  • Published : 2016.12.01
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Abstract

A chemorheological analysis of a no-flow underfill was conducted using curing kinetics through isothermal and dynamic differential scanning calorimetry, viscosity measurement, and solder (Sn/27In/54Bi, melting temperature of $86^{\circ}C$) wetting observations. The analysis used an epoxy system with an anhydride curing agent and carboxyl fluxing capability to remove oxide on the surface of a metal filler. A curing kinetic of the no-flow underfill with a processing temperature of $130^{\circ}C$ was successfully completed using phenomenological models such as autocatalytic and nth-order models. Temperature-dependent kinetic parameters were identified within a temperature range of $125^{\circ}C$ to $135^{\circ}C$. The phenomenon of solder wetting was visually observed using an optical microscope, and the conversion and viscosity at the moment of solder wetting were quantitatively investigated. It is expected that the curing kinetics and rheological property of a no-flow underfill can be adopted in arbitrary processing applications.

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