Reliability Assessment of No-Clean and Water-Soluble Solder Pastes Part IAuthors: Emmanuelle Guéné, Steven Teh
Company: INVENTEC Performance Chemicals
Date Published: 4/14/2015 Conference: Symposium
The water-soluble solder pastes generally show great wettability because of their strong activation but they are also known to have shorter stencil life and to be more sensitive to working conditions as temperature and humidity, compared to the no-clean pastes. Additionally, with the components stand-off getting smaller and smaller, washing residues with water only is more and more challenging due to its high surface tension: the addition of detergent becomes often necessary.
The purpose of this paper is to highlight the differences between these two families of solder pastes to guide users in their choice. This will be achieved through the comparison of several recent water-soluble and no-clean formulations as far as reliability is concerned. First the printing quality will be evaluated (viscosity, tack, cold slump, printing speed according to pressure, stencil life, idle time, printing consistency). Then the reflow properties will be compared (hot slump, reflow process window, wetting ability on different finishes). Finally the residue cleanability will be assessed. The IPC SIR test (method IPC TM 650 126.96.36.199) will be also done to conclude the study. Both standardized tests and production tests will be used to evaluate the performance of these two kinds of solder pastes.
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