The use of tacky fluxes is common throughout the industry in applications such as ball attach, BGA repair and hand soldering. These applications employ different heating profiles, meaning that the fluxes are required to endure a wide range of time and temperature conditions, while not compromising long-term reliability. Tacky fluxes are generally made from the same types of materials that comprise standard solder paste products designed for typical SMT applications. Therefore, the processability and reliability of tacky fluxes that are subjected to a standard SMT reflow profile are well understood. However, when the same tacky flux is subjected to a shorter heating cycle, such as a hand soldering application, it is not necessarily known if the flux residues will have the same reliability as expected when subjected to the typical SMT reflow profile. This paper examines the long-term reliability of no-clean tacky fluxes when subjected to a variety of processing conditions.
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