Webb_IEEE_Trans_Advanced_Packaging_2000.pdf (330.67 kB)
Study of self-alignment of μBGA packages
journal contribution
posted on 2009-01-19, 16:08 authored by K.C. Hung, Y.C. Chan, P.L. Tu, H.C. Ong, D. Patrick Webb, J.K.L. LaiIn this paper, a detailed study of the self-alignment
of BGA 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 BGA
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.
History
School
- Mechanical, Electrical and Manufacturing Engineering
Citation
HUNG, K.C. ... et al, 2000. Study of self-alignment of μBGA packages. IEEE Transactions on Advanced Packaging, 23 (4), pp. 631- 636Publisher
© IEEEVersion
- VoR (Version of Record)
Publication date
2000Notes
This article was published in the journal, IEEE Transactions on Advanced Packaging [© IEEE] and is also available at: http://ieeexplore.ieee.org Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.ISSN
1521-3323Language
- en