The melting point of the flux is lower than that of the solder, and it has good interfacial activity. It can effectively destroy or dissolve the surface oxide film of the workpiece and the solder during brazing, which is beneficial to the wetting and spreading of the liquid solder on the surface of the brazing metal. , So as to obtain a joint with excellent brazing quality. Flux must be used in most brazing applications. The following series of fluxes can be widely used in brazing of copper-based and silver-based solders.

 




Grade
performance
Traits
main application



Element /wt.%




FirmKim


FB101


H3BO3


KBF4

-
Powdery
Low moisture absorption, not easy to agglomerate, suitable for various copper with different melting points
Base, silver base solder.



JB/T 6045

-

29~31


69~71

-



AWS A5.8

-

proper temperature/℃




SO 17672

-

550~850




FirmKim


FB102


KF


KBF4


B2O3

Powdery
Strong activity, wide active temperature range, suitable for various coppers with different melting points
Base, silver base solder.



JB/T 6045

-

41~43


22~24


34~36




AWS A5.8

-

proper temperature/℃




ISO 17672

-

600~850




FirmKim


FB103


KBF4


K2CO3

-
Powdery
Lower melting point and active temperature, suitable for solder with lower melting point.



JB/T 6045

-

94~96


4~6

-



4~6

-

proper temperature/℃




ISO 17672

-

550~750




FirmKim


FB105G


H3BO3


KF


KBF4

Paste
It is liquid and has good fluidity. It can be matched with silver solder and copper-phosphorus solder
It is used for copper-phosphorus-silver solder, but it is not suitable for brass solder.



JB/T 6045

-

＜50


＞20


＞25




AWS A5.8

-

proper temperature/℃




ISO 17672

-

550~750




FirmKim


QJ501Y

Boric acid, methyl borate, methanol, active agent, etc.
Liquid
This kind of flux has no residue, no cleaning, and is widely used in copper-based and silver-based
Solder.



JB/T 6045

-



AWS A5.8

-

proper temperature℃




ISO 17672

-

650~850




FirmKim


QJ403

Methyl borate, methanol, active agent, etc.
Liquid
Put it in the welding torch and use it with flame brazing, there is no residue, and the activity is good.



JB/T 6045

-



AWS A5.8

-

proper temperature/℃




ISO 17672

-

＞450