A No-Clean-Flux Review

The use of no-clean fluxes in liquid and solid form has grown considerably primarily for two reasons: to reduce costs and to minimize the environmental impact of soldering operations. At the same time, considerable work is progressing on no-clean fluxes for solder pastes. In order to build confidence in the technology, it is essential to prove that no-clean fluxes can produce good soldering performance and that electronic assemblies can perform reliably without the need to remove process contaminants. These requirements appear to be ir: conflict. But flux manufacturers have developed a range of products designed to offer the best combination of properties for particular applications. The use of synthetic resins to confer heat stability, and the careful choice of activator systems which are effectively inert under electronic assembly operating conditions have been important factors in making the use of these new fluxes feasible.