Electronic – How to solder this circuit board without breaking it

The first thing I would try is a spring, like the ones used in those old Radio Shack electronics kits from the 80's.

If you can source one long enough, then it might be pretty easy to remove a wire from the middle, provided that you have reasonable spacing between layers.

Maybe some continuous-length extension springs from McMaster will do the trick.

I've said this before, and I'll say it again: How shiny the solder looks is not a reliable indication of the quality of the solder joint.

Even before lead-free solder the shine wasn't a reliable indicator. More reliable than lead-free solder, but not reliable enough for most people.

Here are some things that I look for when evaluating the quality of the solder:

• Consistency: Do all the solder joints look the same? If not, it indicates a variation in the solder process and thus it is more likely to have problems.
• Wetting/Wicking: Did the solder melt evenly and flow onto the mating surfaces, or does it look like the solder beaded up like water on a newly waxed car? Solder that is beaded up could have problems, and hidden cracks under the bead.
• Smooth finish: I'm not asking if it is dull or shiny, but rather is it smooth or are there lumps in it? Lumps are a sign of uneven or incomplete melting.
• Conductive Flux: This one is rare, but important. Some types of flux are conductive, but not everyone is aware of this. Sometimes a board will be reworked with conductive flux but the flux will not be cleaned off correctly (water for water soluble flux, etc.). Check that the proper flux was used in the proper way. Note: Some flux leaves a residue and this is OK as long as the residue is not conductive even though it might look bad.
• Cracked Solder Joints: Often this can only be seen using a microscope, and sometimes not even then.