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The Impact of Crevices beneath Surface Mounted Devices on the Cleaning Efficiency

The Impact of Crevices beneath Surface Mounted Devices on the Cleaning Efficiency The transition to surface mounted device SMD technology in electronics manufacturing has placed new demands on the postsolder cleaning process. For spacecraft electronic systems it is of the utmost importance that all flux residues be removed. This paper reports the results of an investigation of the impact of component standoff heights and the distance between solder joints on the cleaning process efficiency. The capability to clean beneath large chip carriers was evaluated for four different cleaning methods using isopropanol or CFC113 Freon TMS as cleaning liquid. The results show that the cleaning efficiency decreases considerably if the standoff height is less than 240 m for 100 mil pitch chip carriers. For 50 mil pitch chip carriers the standoff height needs to be greater than 240 m to achieve high cleaning efficiency. The cleaning efficiency beneath chip carriers with small standoff heights can be increased by using ultrasonic cleaning. However, a very thin layer of white residues is left where the flux has been removed if isopropanol is used as the cleaning liquid. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Soldering & Surface Mount Technology Emerald Publishing

The Impact of Crevices beneath Surface Mounted Devices on the Cleaning Efficiency

Soldering & Surface Mount Technology , Volume 3 (2): 7 – Feb 1, 1991

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0954-0911
DOI
10.1108/eb037754
Publisher site
See Article on Publisher Site

Abstract

The transition to surface mounted device SMD technology in electronics manufacturing has placed new demands on the postsolder cleaning process. For spacecraft electronic systems it is of the utmost importance that all flux residues be removed. This paper reports the results of an investigation of the impact of component standoff heights and the distance between solder joints on the cleaning process efficiency. The capability to clean beneath large chip carriers was evaluated for four different cleaning methods using isopropanol or CFC113 Freon TMS as cleaning liquid. The results show that the cleaning efficiency decreases considerably if the standoff height is less than 240 m for 100 mil pitch chip carriers. For 50 mil pitch chip carriers the standoff height needs to be greater than 240 m to achieve high cleaning efficiency. The cleaning efficiency beneath chip carriers with small standoff heights can be increased by using ultrasonic cleaning. However, a very thin layer of white residues is left where the flux has been removed if isopropanol is used as the cleaning liquid.

Journal

Soldering & Surface Mount TechnologyEmerald Publishing

Published: Feb 1, 1991

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