SMT soldering questions

On 6/24/10, Keith M <keithvz at verizon.net> wrote: Looks nice. That would depend on your style. I've used larger (1/32") tips with success, but occasionally I've needed a smaller tip for touch-up work. For the flux-wet-then-drag technique for QFPs, you want a larger tip. The same size tip can probably be used successfully with 1206-sized parts, but if you intend to do a lot of work with 805s or smaller, a finer tip might be recommended, or if your parts density is so tight that you are lifting your iron in the air to clear adjacent parts. That depends on your solder type, and how much mass you'll be heating up, but for leaded solder, that's not a bad place to start. If you need more heat, add more heat, though over 700F and you are probably boiling off your flux or risking lifting your pads. If you are working on ultra-low-cost PCBs (like dark brown case resin), don't get too hot or you will definitely have lifting issues. For SMT projects, you are probably using modern, high-quality FR-4 boards, so that's less of an issue. That's one form. Injectable solder paste can also be handy. I also use larger solder, but apply it carefully to avoid overflowing the joint. I have a flux pen. It does 90% of what I need. I keep thinking about a flux syringe but haven't bothered buying one yet. A solder sucker, solder wick, magnification with lots of light if you can't read the numbers on the parts, fine-point tweezers, optionally a vacuum picker to collect parts, and scotch tape (I've been known to tape down one end of 1206 parts so they don't move while I solder the other end - that was a tip given in the Heathkit SMT course I did 20 years ago). -ethan