wolfman wrote: 17 Mar 2023 12:59
BTW: I would appreciate a recommendation for flux and a solderstation.
I have two types of flux:
- liquid (but it burns nearly immediately away)
- gel (very sticky but somewhat useful)
I'd suggest that the solder may be lead free and have a higher melting point than 340C, at least that is my own experience. I tend to use 370C for everything, but a lot of it is what suits your way of working.
Personally the two types of flux I use are Kingbo RMA-218 and for other jobs I use Topnik RF800. The latter I usually use for soldering sockets and ICs in as it gets into the vias nicely despite burning away quickly.
The RMA-218 is somewhere between liquid and a gel. I do have another little tub of thick gel flux, but it really is a bit too thick, and though it melts well, it's harder than with the RMA-218, which is applied using a syringe.
For surface mount chips, to reflow I'd tend to use a soldering iron and drag solder with a clean up using wick if needs be (I use Chemtronics stuff), but whatever you do you need to avoid putting too much heat into the board as it's liable to lift pads and traces.
Hot air I do avoid generally, as older 2 layer boards can scorch easily, though the RMA-218 does seem to help as it does form a bit of heat barrier when it melts. I mostly use it for thicker multi-layer boards that are a bit more able to resist the heat. Flow and temperature is pretty important for hot air.
Solder stations, well difficult to say without knowing what you want to spend. I have a relatively inexpensive Chinese dual soldering/hot air station. IIRC it came in about £100 -£150 and it does everything I need, and I usually work on 8 and 16 bit machines. To be fair, the soldering iron was very poor until I got a new set of bits for it, and after that it has been really good. I also have a desoldering gun that was also about £100, a Duratool one, but the same model is all over the place and rebranded. I still also have a 25 year old Maplin temperature controlled iron, and that is good for areas where there are large thermal masses.
The bottom line is though, whatever type of soldering you're doing, you really need to practice or you risk damaging whatever you're working on. The biggest mistakes I see people make are to linger too long or push too hard because they're not using enough heat causing pad/trace damage and to incorrectly assume all the pins of something are free and ripping the vias/traces up as a result.
It's all about practice, and it's something you learn. I still make mistakes from time to time, and then have to make repairs later.
It's worth remembering that different boards tolerate different handling, for example my Dragon 32 is extremely fragile when it come down to soldering, but my TRS-80 Model1 can tolerate quite a bit more and still come back for more.