Speaking as a guy who knows flux – they are not all created equal. Flux use spans many industries, some of which can get away with crude ingredients and manufacturing procedures. Plumbers, for instance, don’t care if the flux they use is ultra-filtered, de-gassed, or dyed.
Package assembly deserves the best though. Please don’t just settle for a run-of-the-mill flux when there are fluxes designed specifically for your type of application.