SMTA International Conference Proceedings


Author: Deepak Manjunath
Company: State University of New York
Date Published: 9/25/2005   Conference: SMTA International

Abstract: This paper presents the methods researched and implemented to minimize flux residues on the component body. No-clean solder pastes have the tendency to leave flux residues. Although these residues do not lead to any defects, their presence on the board or component body is aesthetically unappealing. The primary objective of this experimental study was to eliminate/minimize the amount of flux residues which were commonly observed on the component body.

The capacitor locations, which prominently exhibited flux residue on the component body, were targeted during these experiments. Two sets of experiments were conducted during this research effort. In the first set of experiments, the effect of paste volume was studied. The result of this experiment indicated that around 25% reduction in the solder paste volume from the outer portion of the pad minimized the flux residues. In the second set of experiments, the effects of different reflow profile parameters were studied and the profile that yielded the best results was established.

The results of this experiment indicated that using a profile with long soak time minimized the amount of flux residues on the component body. Quick turn reliability studies like thermal cycling and pull tests were carried out to determine the reliability of the solder joints.

Key words: flux residue, no-clean solder paste

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