What Is the Difference Between Brazing and Soldering?

Soldering and brazing are both effective ways to join two or more metal materials. Both techniques use a liquefied metal filler that wets the joining surfaces via capillary action, which improves the coverage and bonding strength of the filler as it hardens. Simpler and less energy-intensive than welding, brazing and soldering are popular options for many industrial and commercial applications.

The main difference between brazing and soldering is the filler metal’s melting temperature. Processes above 840 °F constitute brazing, while soldering occurs below that threshold. Read on to learn more about each process and its respective advantages.

Soldering

In addition to melting the filler metal below 840 °F, soldering requires a flux to clean the joining surfaces and promote flow of the filler, maximizing coverage over the base materials. Flux also prevents oxidation. 

While soldering used to rely on lead-based fillers, it has since adapted to legal restrictions on lead by using effective alternatives such as copper, antimony, tin, bismuth, silver, or indium. Different soldering fillers and techniques make it possible to solder a wide variety of base materials, including:

Typical heat sources for soldering include open flame, induction, or resistance heating. Choosing the right soldering method depends on the application, with the most common being:

• HVAC/R, heat exchangers, refrigerant lines, heating and cooling components
• Electrical,  contacts, cable connectors, printed circuit boards (PCBs)
• Plumbing, to create an effective seal around pipes, joints, fittings, and valves
• Metal Cans, to attach handles, lids, nozzles, and more  

Advantages of Soldering

Soldering offers several key advantages:

• Capable of joining dissimilar base materials
• Requires lower processing temperatures and lower power input than welding and brazing
• Minimal thermal distortion and residual joint stress
• Suitable for thin-walled parts

Brazing

Thanks to its high bonding strength, brazing has become one of the most common metal joining methods for many industrial and commercial sectors. Brazing uses heat sources such as vacuum, furnace, flame, induction, and resistance brazing.

All braze fillers are heated above 840 °F but below the melting point of the base materials being joined. As with soldering, most brazing methods use a flux material to clean the base metal surfaces, prevent oxidation, and enhance capillary action. Brazing is compatible with a wider range of base metals: 

There is also a range of primary braze filler metals, including aluminum, copper, phoscopper, nickel, brass, bronze, silver, and gold. For specialty applications, these filler metals are sometimes alloyed with other elements to improve various performance properties of the filler. Due to these benefits, brazing is a popular and versatile bonding method across most industrial and commercial applications.

Advantages of Brazing

Brazing offers many advantages, especially compared to soldering and welding:    

• Joins dissimilar base materials
• Requires less heat and power input than welding
• Produces stronger joints than soldering or welding
• Creates joints with minimal residual stress and thermal distortion
• Does not require post-processing heat treatments

Soldering and Brazing Solutions From Fusion, Inc.

From automated brazing and soldering equipment to custom filler materials, Fusion, Inc., is at the leading edge of specialty metal joining solutions. Our soldering and brazing products and services are the culmination of over 90 years of innovating these metal joining processes.

Family-owned and operated since our establishment in 1933, Fusion, Inc. is a trusted consulting partner for numerous industries looking to implement automated brazing and soldering solutions. Our comprehensive solutions include:

• Application-specific soldering and brazing paste alloys
• Applicator devices and accessories, suited for a broad range of brazing and soldering challenges 
• Automated machinery to streamline and scale your metal joining operations

Contact us or request a consultation to discuss your organization’s brazing or soldering needs.