Debrazing and Rebrazing of Copper to Copper Strip

Objective
We have evaluated several coil designs for debrazing and rebrazing copper angle brackets to copper strips. The goal of this application was to achieve the desired debrazing and rebrazing in less than 1 minute.

Equipment
UltraHeat L 50/50 Power Supply
HS -35LF
Pancake earmuff coil
Rectangular coil

Test 1

Materials
Copper right angle bracket, 0.170” (4.3mm) thick
Copper strips, 0.05” (1.3mm) thick

Key Parameters
Power: 25 kW
Temperature: Approximately 1400° F (760° C)
Time: 60 sec to debraze and reflow existing braze

Test 2

Materials
Three 0.1″ (2.5mm) thick copper plates
Two 0.06″ (1.6mm) thick copper plates

Key Parameters
Power: 25 kW
Temperature: Approximately 1400° F (760° C)
Time: 60 sec to debraze and reflow existing braze

Process 1:

• Power was limited to 25kW to represent the use of a 25 kW power supply.
• The assembly was positioned in between the two coils (see photo and video).
• Induction heat was applied until the existing brazed bond was reflowed.

Process 2:

• The larger braze sample was positioned below the coil with the coil ID centered above and around the bracket.
• A non-conductive solid was used to counteract electromagnetic forces and keep the coil in place above the bracket.
• A heat cycle of 60 seconds was sufficient to reflow the existing braze in this area.

Results/Benefits:

• The split earmuff coil, where applicable, will provide a more efficient heat source as the RF field is directed to both surfaces of the braze area.
• Where this coil design is not usable, a coil similar to the modified coil used for test 2 will provide the required heat for the process.
• These coils require a fixture to counter the electromagnetic forces that act on the coil and move it upward away from the surfaces to be heated.

Video