Study of Self-Alignment of μBGA Packages

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal

2 Scopus Citations
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Author(s)

  • K. C. Hung
  • P. L. Tu
  • H. C. Ong
  • D. P. Webb

Related Research Unit(s)

Detail(s)

Original languageEnglish
Pages (from-to)631-636
Journal / PublicationIEEE Transactions on Advanced Packaging
Volume23
Issue number4
Publication statusPublished - Nov 2000

Abstract

In this paper, a detailed study of the self-alignment of μBGA packages is presented. Complete self-alignment can be achieved even for a misalignment of the package of larger than 50% off the test board pad centres. A small residual displacement of the package from perfect alignment after reflow is observed. The reason for this displacement is the action of gas flow viscous drag on the package during reflow. The use of eutectic SnPb solder paste slightly reduces self-aligning ability, due to the increase in the solder volume, which reduces the restoring force. Exposure of the solder paste to a 25°C and 85% RH humidity environment also has a detrimental effect on the self-alignment of the μBGA package, due to solvent evaporation and moisture absorption in the paste causing solderability degradation. The self-alignment of the package is also affected when there is slow spreading of molten solder on the pad surface. This is attributed to the reduction of restoring force due to the decrease in effective wetting surface area of the board pad.

Research Area(s)

  • Gas flow effect, self-alignment, μBGA package, wetting

Citation Format(s)

Study of Self-Alignment of μBGA Packages. / Hung, K. C.; Chan, Y. C.; Tu, P. L.; Ong, H. C.; Webb, D. P.; Lai, J. K L.

In: IEEE Transactions on Advanced Packaging, Vol. 23, No. 4, 11.2000, p. 631-636.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal