3 ms·

The NASA handbooks are good. I like the one for rework that shows neatly staked wires. There are a couple of subtleties you could miss on this one though: 1)

The NASA handbooks are good. I like the one for rework that shows neatly staked wires. There are a couple of subtleties you could miss on this one though: 1) On page three, that exposed end of the lead is a defect if you're NOT going to conformally coat the board. If you don't know what a conformal coating is, it's a defect. 2) On page eleven, flux residue. Sure, for NASA's applications. For most commercial applications, the IPC rule is "excessive flux residue". For prototypes, one-offs, and hobby projects, my rule of thumb is, if you can't measure the difference removing flux makes, leave it there. Incompletely cleaned flux can be more corrosive than undisturbed flux. Also, no-clean flux should be called "never clean" flux. Never clean it with ordinary methods because you will never get it clean.

lmilcin 6y ago
I dislike no-clean. I like my boards pristine with nice, shining leaded solder and no residues.
- buescher 6y ago
  That's fine, I like them that way too! But as a hobbyist, you risk leaving corrosive salts on the board or worse, sloshing them into electromechanical parts like switches, pots, unsealed relays, sounders, etc. Getting to "pristine" is harder than a lot of people think. There's a vicious cycle in production where assemblers will use too much flux, get flagged in an IPC-610 evaluation, try to clean the boards, and then get flagged for high ionic contamination in the next evaluation. You can't see the salts you leave behind from incomplete cleaning. Beginners should not ever clean flux. Most hobbyists should never need to clean flux. Professionals should have data driving any decision to clean flux.
  - lmilcin 6y ago
    Fortunately, I rarely risk anything if the board fails. And if it does I always try to understand what caused the failure. I never considered flux compatibility between my solder rosin core and the flux paste and never considered measuring salt residues on the board. I almost exclusively use the same Kester sn64pb37 rosin core solder and MG Chemicals #8342 RA rosin flux paste. Both must be cleaned promptly. Now, I don't bother cleaning if I don't intend to use the board after I test it (like when I do prototyping) but anything else gets a thorough wash. I use various PCB cleaners, typically ethanol (not IPA!) based and then rinse boards in electronic water. I never saw any oxidation on any of the traces unless there was some external contamination.

lmilcin 6y ago

I dislike no-clean. I like my boards pristine with nice, shining leaded solder and no residues.

buescher 6y ago
That's fine, I like them that way too! But as a hobbyist, you risk leaving corrosive salts on the board or worse, sloshing them into electromechanical parts like switches, pots, unsealed relays, sounders, etc. Getting to "pristine" is harder than a lot of people think. There's a vicious cycle in production where assemblers will use too much flux, get flagged in an IPC-610 evaluation, try to clean the boards, and then get flagged for high ionic contamination in the next evaluation. You can't see the salts you leave behind from incomplete cleaning. Beginners should not ever clean flux. Most hobbyists should never need to clean flux. Professionals should have data driving any decision to clean flux.
- lmilcin 6y ago
  Fortunately, I rarely risk anything if the board fails. And if it does I always try to understand what caused the failure. I never considered flux compatibility between my solder rosin core and the flux paste and never considered measuring salt residues on the board. I almost exclusively use the same Kester sn64pb37 rosin core solder and MG Chemicals #8342 RA rosin flux paste. Both must be cleaned promptly. Now, I don't bother cleaning if I don't intend to use the board after I test it (like when I do prototyping) but anything else gets a thorough wash. I use various PCB cleaners, typically ethanol (not IPA!) based and then rinse boards in electronic water. I never saw any oxidation on any of the traces unless there was some external contamination.