Soldering terminology

Propagation velocity of a fluxing agent by instillation onto a hot (e.g. 250 °C) copper plate. According to the JIS standard, the propagation area is measured after 30 seconds. In practice, however, one must know exactly how the flux propagates. To complete a phase of operation within a few seconds, flux X₁ (with the initially fastest growing area) must be used instead of flux X₂ with the larger absolute spread. This fact is demonstrated by measurements with the System VEL -500 model developed by Nihon Almit and Shinku Riko.