We broke out 4 different types of flux we had in the workshop and tried them with surface mount parts. Liquid flux, flux paste, syringe flux, and a flux marker are all tested. We used each to solder a 0805 resistor and some pins of a QFP 0.5mm pitch IC to an xQFP protoboard.
- Edsyn flux in a syringe
- Sjaak’s liquid flux from Akihabara
- Kester #951 flux marker
- Solder paste from a reader in Spain
Our preferences in order are:
- Flux syringe – very easy to work with, low fumes, solder flows really well
- Liquid flux – we were surprised that a liquid flux worked so well, it could have been #1 if it created fewer fumes
- Flux paste (probably rosin-based) – thick and viscous, kept the solder where we needed it
- No flux at all – fine for passive parts like resistors and capacitors, harder to work with on the QFP chip
- Kester flux marker – overall this was worse than no flux at all
xQFP protoboards make it easy to prototype with surface mount parts, and are currently available in 0.50mm, 0.65mm, and 0.80mm for $10 each. Single xQFP breakout boards are also available in 0.50mm, 0.65mm, and 0.80mm for $3.
Check out our other Workshop videos.