Manufacturing considerations when implementing VOC-free flux technology

The problem is not limited only to rosin fluxes and solvent cleaning, but also occurs when water soluble fluxes are used and when either flux type is removed with water. The soldering and cleaning processes involve so many chemicals in the flux, circuit board, components and cleaning agents that a complete understanding of the reactions is very difficult if not impossible. There are white residue problems with water soluble fluxes and many of the causes not related to the flux compositions are the same as for rosin fluxes.

The essential quality features required for these future applications are provided by the multivacuum soldering process. In the multivacuum soldering process assemblies are subjected to several vacuum applications during the soldering process, with the option of applying vacuum processes both before and during the melting of the solder paste.

Tin-Silver-Copper alloys are the primary choice for lead-free SMT assembly. Although there are other options available such as alloys containing bismuth or indium and other elements, tin-silver-copper solders, also known as SAC alloys are by far the most popular. They are used by approximately 65% of users, as last surveyed by Soldertec in 2003.