Soldering and Brazing

Soldering and Brazing are very similar processes, in fact the difference between the two is that brazing takes place at temperatures over 450 deg C and soldering takes place below this temperatures. In both cases, a filler metal is melted into the joint between the two parts to connect them, the parts themselves remain unchanged.

Soldering

Soldering is manly used to join parts in electronics, jewelery and plumbing. The main benefit is that the solder materials usually has a low melting temperature so the parts won't get too hot in the process. This can be especially important for electrical components which may be damaged by too much heat.

Solder materials are usually an alloy of Tin and other metals such as zinc or aluminium depending on what is being joined. Most solders these days are 'lead free' because of the health hazards associated with breathing lead fumes.

Advantages of soldering:

• Lower energy requirements than brazing or welding
• Various portable heating methods will work
• Good electrical conductivity across joint
• Easy to repair

Disadvantages of soldering:

• Joints are not very strong
• Joints can melt or weaken if the temperature is raised

Brazing

Brazing requires hotter temperatures than soldering because of the filler material used which is most commonly alloys of aluminium or copper . Unlike welding however, it does not involve melting the parts themselves. Instead, the filler material is drawn in between the parts by capillary action where it forms the bond. The parts must be close fitting or the material will not flow, flux is also required to ensure the joint is clean and that no oxides form during heating.

Advantages of Brazing:

• Lower heat than welding so tighter tolerances can be used and less heat distortion
• No secondary cleaning up or joint required
• Can join dissimilar metals together
• Easy to automate process

Disadvantages of Brazing:

• Not as strong as a welded joint
• Joint can be weakened if used at high operating temperature
• Joint must be very clean before brazing
• Brazing rod is expensive