Hybrid S-Bond joining processes eliminate the use of fluxes and have been shown to be more effective since it completely joins with the S-Bond filler metals. The methods that are recommended to minimize the use of S-Bond, yet still achieve fluxless joining are as follows:
- Heat base materials to S-Bond melting temperature.
- Melt a small amount of S-Bond onto the joining surfaces.
- Add ~ 0.1g/cm2 to the opposing surfaces to be joined
- Add S-Bond to the opposing joint surface.
- Mechanically spread the S-Bond layer to completely cover the joint area (brush, spatula or ultrasonics).
- Melt “conventional” solders onto the S-Bond layer on the bottom base and agitate to assure wetting to the underlying S-Bond layer.
NOTE: Sn-Ag, Pb-Sn, Sn-Bi, In solders can be used
- Add enough “conventional” solder to the base to “float” and slide the top surface of the joint onto the conventional solder and provide excess solder to fill any gaps.NOTE: The sliding of the molten S-Bond / solder surfaces onto one another eliminates entrapped air and mechanically shears the surfaces of the S-Bond layer to the bottom “conventional “ solder layer on the base.