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Paste Solder Fluxes

Non-Corrosive Fluxes

See chart below. Fluxes are classified as Non-Corrosive when their residue after soldering will not corrode and eventually destroy the joint if allowed to remain. Generally incorporating a rosin base, these fluxes contain mild organic acids which are neutral at room temperature but become slightly acidic upon heating. Neutral, rosin fluxes are particularly useful in electrical applications, where their non-conductive, non-corrosive residue may be safely left on the assemblies.

Intermediate Fluxes

See chart below. These fluxes usually consist of mild organic salts, with considerably stronger fluxing action than non-corrosive types. Residue after soldering is normally not harmful to the soldered joint. However, residue should be removed whenever possible, as moisture in the atmosphere may initiate corrosion.

Corrosive Fluxes

See chart below. Most corrosive fluxes contain active inorganic acids and salts. Due to their increased strength and ability to quickly remove surface oxides, these fluxes are ideally suited to high-speed, automated soldering operations. Although corrosive fluxes generally produce the most reliable soldered joints, their residue after soldering must be removed, or it will eventually attack and destroy the joint.

Fusion Solder Flux/Binder Systems

Fusion System Key Flux/Binder Properties Base Metal Compatibility
Flux Activity Range (typical) Restrictive Level Residue Residue Removal Brass Copper Stainless Cold Roll Other
Flux Class: Non-Corrosive
GPR 300-525°F (149 – 273°C) Fair Spread – alloy / process dependent Non-Corrosive Organic solvent / hydrocarbon solvent Y Y N N LT
MBC 300-595°F (149 – 313°C) Fair Spread – alloy / process dependent Non-Corrosive Organic solvent / hydrocarbon solvent Y Y N N LT
LPS 300-525°F (149 – 273°C) Very Restrictive Non-Corrosive Organic solvent / hydrocarbon solvent Y Y N N LT
Flux Class: Intermediate
WC 300-525° F (149 – 273°C) Restrictive Moderately Corrosive Hot Water / Detergent Y Y Y Y LT
PWC / PMS Family 300-525°F (149 – 273°C) Very Restrictive Moderately Corrosive Organic solvent / hydrocarbon solvent Y Y LT Y LT
PA / PAD / PAN Family 125-525°F (52 – 273°C) Very Restrictive (PA) Moderately Restrictive (PAN/PAD) Moderately Corrosive Hot Water / Detergent Y Y LT LT LT
SUN 300-525°F (149 – 273°C) Moderately Restrictive Low Corrosivity Hot Water / Detergent Y Y LT LT LT
Flux Class: Corrosive
SFC, FCC, 2JN, SMH Family 300-600°F (149 – 316°C) Moderately Restrictive (SFC, FCC, 2JN) Very Restrictive (SMH) VeryCorrosive Detergent Water / mild acid Y Y Y Y LT
PPP, SSX, SSE Family 300-600°F (149 – 316°C) Restrictive Very Corrosive Detergent Water / mild acid Y Y Y Y LT
WCC, WCE, WCS Family 300-600°F (149 – 316°C) Moderately Restrictive Moderate to Very Corrosive Detergent Water / mild acid Y Y Y Y LT

Y = Common use
N = Not typically recommended
LT = Lab testing required (Depends on base metal, filler metal, and solder process)

For more details on the above products, download our Paste Brazing Brazing & Soldering Alloys brochure.


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