Copper is one of the more common base metals used among brazing and soldering applications. Copper can be joined to other base metals including brass, steel, and aluminum. Brazing with copper is most popular in many HVAC, electrical, valve, and plumbing applications.
If sealing a copper joint is important and strength is not an issue, solder filler metals can be used to solder copper. A variety of Tin/Lead solders can achieve good seal properties, however, there are a number of Lead-Free filler metals to consider. Fusion 430, a 96.5Sn/3.5Ag filler metal is a good choice for soldering copper.
If strength and seal are required, brazing filler metals are necessary. Brazing copper to copper and copper to brass can be achieved with low cost Phos/Copper (BCuP) filler metals. Fusion 1310, a 86.25Cu/6.75P/7Sn filler metal is an ideal, low-cost choice for these applications.
Brazing copper to steel should not be done with BCuP filler metals due to the possibility of phosphorus embrittlement, a weakening condition created by base metal/filler metal interactions. Fusion 1205, a 56% silver filler metal is a good choice for copper to steel brazing applications.
Due to the increased strength of brazing alloys, a properly fabricated brazed joint is stronger than the base metals themselves.