Induction Soldering Electrical Circuits

Induction Soldering Electrical Circuits Board With High Frequency IGBT Soldering Heater Objective To heat multiple joints on flex circuit strips to 180-200°F within seven seconds for a soldering application. Material Copper bonded to polyester flex circuit strips, Solder Plus Paste 63NC-A, 0.0625” thick Teflon sheets Temperature 183°F Frequency 278 kHz Equipment DW-UHF-4.5kW power supply, remote heat station with one 1.2 μF capacitor and a specially designed induction coil. Process A specially designed induction coil was used to provide even heat in the area where the fingers of the flex circuits overlap. Initial tests were done to establish a heating pattern and determine time-to-temperature. After a very light coat of the solder paste was applied to the circuit connections, a small amount of pressure was applied to the Teflon sheets to hold the circuits together. RF power was then applied for 6.5 seconds to flow the solder paste and bond the flex circuits Results Consistent and repeatable results were achieved using the DW-UHF-4.5kW power supply in 6.5 seconds at 183°F.