Experimental study on the thermo-mechanical effects of underfill and low-CTE substrate in a flip-chip device

Yasuyuki Morita, Kazuo Arakawa, Mitsugu Todo, Masayuki Kaneto

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10 Citations (Scopus)


Moiré interferometry was used to analyze the thermal deformation of four flip-chip devices mounted on FR-4 substrate and a new multi-layer substrate, with and without underfill. Thermal loading was applied by cooling the devices from 100 °C to room temperature (25 °C). The effects of underfill and the low-CTE (coefficient of thermal expansion) substrate on thermal deformation were investigated. The experimental results showed that the underfill curved in a manner similar to the silicon chip. For the flip-chip devices mounted on the multi-layer substrate, the CTE mismatch between the silicon chip and substrate was reduced, and bending deformation decreased. Of the four flip-chip devices studied, the underfilled flip-chip device mounted on the multi-layer substrate had the least deformed solder balls.

Original languageEnglish
Pages (from-to)923-929
Number of pages7
JournalMicroelectronics Reliability
Issue number5-6
Publication statusPublished - May 1 2006


All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Safety, Risk, Reliability and Quality
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering

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