On Tuesday, December 18, 2018 at 7:29:36 PM UTC-5, gregebert wrote: > > Paul - Can you post some details about the hot-air soldering/reflow you > did ? > > I'm soldering my SMT devices manually by hand because my casual > experimenting with a heat-gun got bubbled PCBs and very hot (and probably > damaged) ICs. >
When doing assembly (as opposed to re-work) a few parts at a time, the idea is to pre-heat the board (usually via IR to the underside) to a bit below the melting point of the solder paste you're using, then use the air gun to melt the solder paste you put under the parts you're soldering. That way you don't need a ton of very hot air coming out of the nozzle, since that would end up overheating the component before the board got hot enough for the paste to stick to the traces. Re-work is a bit more of a mixed bag, since you may have components on both sides of the board and the parts you're trying to remove are usually larger than the ones you want to leave in place - people starting out tend to blow things like resistors / caps off the board while heating the part to be removed. Even with the exact matching nozzle on the air gun, that air has to go somewhere. Pre-heat also helps with this, though you'll likely want a lower temperature so any parts on the underside aren't at risk. Preheating also helps with some through-hole rework - I do a lot of work on Cisco boards (8 to 12-layer) and things like power supply caps are connected to interior layers that are pretty slab-like. And Cisco doesn't seem to like to use relief areas arround those inner-layer holes -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/ce4bb062-1a8d-4f3d-a46a-52854172e664%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
