Most rework fluxes
are purchased from the same supplier as the primary attach fluxes
, and many common combinations are pretested for compatibility by their supplier.
require the addition of a wetting agent or an organic co-solvent during formulation to reduce the surface tension of the material.
can be broadly categorized as passive or active.
One of the rosin emulsion fluxes
(Flux P) showed promise; however, it did not pass Bellcore SIR testing and was removed from consideration.
Chloride remaining on the assemblies after exposure to H1 fluxes
R, RMA, and RA fluxes
are generally used for hand-soldering operations, and require different levels of cleaning.
The alkaline fluxes
melt at a lower temperature than the aluminum and when no molten aluminum is present, the flux will react directly with the crucible wall.
I've learned from the chemists I work with that no-clean fluxes
are designed to fully activate and deactivate within specific time-temperature windows.
These exhibit exceptional hot strength, high density, low porosity, and resistance to corrosion and penetration by slag and fluxes
However, much of the industry has chosen not to clean after soldering, instead opting for low-solids fluxes
designed to be left on and benign when properly heat-activated.
The first part of this series provided a basic understanding of the science of fluxing, focusing on applications, handling and delivery, and the composition of solid fluxes
Respect the storage guidelines on the flux datasheet and be sure that water-based fluxes
have not been frozen during shipping.
offer several special purpose applications, the propensity for aluminum to oxidize is the main reason fluxes
Converting from SnPb37 to Pb-free (such as SAC) requires fluxes
with better wetting and cleanability.
Wirch from Acustar Canada's Etobicoke Casting Plant list the sources of hydrogen contamination as: * furnace atmosphere; * moisture from refractories, dirty skimmers; * hydrated corrosion products in the charge, such as weathered ingot and scrap; * oil contaminated turnings, chips or scrap; * damp fluxes