- The solder used in for much of consumer electronics melts at temperatures of about 180°C. So temperature-wise there is no problem using a normal oven to do the job.
- Even at 180°C components will unavoidably get damaged. Different components react to heat differently.
- The first to suffer are typically connectors with plastic housings (e.g. to interface with a PC etc.). They are extremely difficult to remove without damaging the plastic. Other components tolerate heat better. The lifetime of aluminum electrolyte capacitors however is likely to be reduced by repeated heating. With ICs, there is less of a risk of classic thermal damage but rather due to mechanical stresses resulting from too fast heating or cooling. - On the whole however, components will not suffer too much if you don't keep them heated for more than a few minutes.
- If you want to avoid using an oven for heating, you can fix the board horizontally in a vise and heat it from below with a heat-gun until the solder liquifies. Then take the board with pliers and tap it vertically on the table. The components will fall off quite easily.
Attention: with a heat-gun it is easy to over-heat the board or heating the board too rapidly. Solder in vias may be ejected outwards due to the rapid heating: wear eye-protection if you really want to do this.
Generally however it is not worth recovering components en masse from assys: What you recover will typically be proprietary chips you cannot really use, tiny smd capacitors too small to handle, and unmarked smd capacitors and inductors. - I propose you only remove those components that you really want/need.
C: definitely the assembly shop, if you have the wallet for it. That's for you to decide. Ask some quotes, and decide if doing it yourself is worth the effort. Since this is a hobby project you may think your time is free, but then it has to stay fun as well, hasn't it?
edit
Just got this in a mailing from DesignSpark: fundraising may get you started to have it done by a shop. Erik raised 313 218 dollar for a 5 000 dollar target.
(end of edit)
Alternatively, B: Again, get a quote for a stencil. Yet, even applying the solder paste manually will take less time than hand soldering, which I would not recommend: the resistors and capacitors are not much of a problem, but the ICs may take quite some time if you want to do it proper, i.e. all pins soldered and no short-circuits.
Not A: it takes too long and it's messy. I would only do it myself if I could use the oven.
Remember that Jobs and the Woz also hand-assembled their first batch of Apple computers :-)
I am replacing a toaster oven heating element and found this loose connection & burn on the circuit board. Does this look like I could successfully solder it back in place?
Best Answer
Yes, you should be able to solder that back. Be 100% sure to use electronic grade flux core solder and not plumbing solder.
It looks to me like the assembler was rough and cracked the solder joint (latent failure), which then oxidized and heated up causing the damage you see. The heating is apparently confined to just the joint area, so I don't think anything else is wrong.
Maybe try cleaning the area with an old toothbrush and isopropanol and then gently scraping the solder mask off (leaving clean copper) around the connections. If the connection doesn't look perfect, lay a wire from the pads to that bare section of the trace it connects to and run solder all over it.