Following the success of NC-506 (No-Clean flux for mounting spheres on BGA packages) is a halogen-free version – NC-585. I’ve been working with this flux quite a bit lately to see how it stacks up with the industry leading NC-506.
The first thing I noticed was the lower tack and viscosity of NC-585. This was apparent in initial pin-transfer testing. The flux rolls well under the squeegee blade and transfers a large amount of flux per pin. Because the transfer is so pronounced, NC-585 may bridge between very closely spaced pins, we will need to take a closer look at this later. Normal BGA pitches are no problem at all with this flux.
The wetting of this material was surprising. I didn’t think any halogen-free flux would be able to compete with NC-506, but NC-585 had even better wetting characteristics on bare copper and ENIG surfaces at Pb-free temperatures with SAC 387.
The future of this flux looks promising, as does the future of powerful halogen-free fluxes.