Induction Soldering of Copper tubes and wires

Application: Soldering

Industry: Medical

Application Objectives: Demonstrate the feasibility of replacing an open-flame torch with a safer, more consistent induction heating solution using a compact 2 kW system to solder medical-grade copper components.

The challenge: The customer needed to eliminate variability and safety issues associated with torch soldering. Key challenges included achieving reliable, clog-free joints using alloy 99C Solder (1.6 mm), maintaining a maximum process temperature of 400 °C, and ensuring the system could handle small copper assemblies without overheating or discoloration.

Equipment:

• UltraFlex SMT-2/200 (2 kW) + HS-4W Heat Station
• 3-turn butterfly coil
• Footswitch

Materials:

• Copper tubes (6–8 mm)
• Solid copper wire
• Alloy 99C solder (1.6 mm)
• Flux
• Insulation

Key Parameters:

• Power: 1.6 kW (100% current regulated)
• Cycle time: ~15 seconds
• Max temperature: ≤ 400 °C
• Duty: 6 cycles x ~3 minutes

Process:

Multiple tests were performed using manual and ring-based alloy feeding. The operator introduced parts into the coil manually and activated heating via a foot pedal. Flux was applied before each cycle. Tests revealed that solder quantity and pipe fit significantly affected joint integrity. One-ring setups underfilled the joint, while two-ring setups provided better results. In cases of clogged joints, parts were successfully reheated upside-down to clear excess alloy using gravity – a demonstrated advantage of precise induction control.

Results and Conclusions:

All tests proved the feasibility of replacing torch soldering with a 2 kW induction system. Reliable joints were achieved under 15 seconds per cycle, with minimal discoloration and no need for operator guesswork. Upside-down reheating resolved clogging issues effectively. The open-type coil worked well for handling, though future improvements with closed-type helical coils could enhance efficiency. This setup offers a clean, repeatable, and scalable soldering alternative, ideal for medical manufacturing environments.

Reference Info: AR 3464-8839