November 24, 2013 at 12:35 am #20283
I ask this question for those who have not made the mistake I did: any suggestions on how to best remove the flux residue off of the Peggy 2 board after assembly is complete?OK, not having bothered to ask the question before acting, I decided that Isopropyl Alcohol followed by a water rinse would probably do the trick. Bad, bad, really dumb idea: yeah it removes the flux, and the shiny finish on the board, leaves a white sticky film (which I assume is the former board finish), and appears to have lightly oxidized the solder joints. Other than that, it was a huge success. Anything I can/should do at this point? The board seems to be working fine, I’m mainly concerned with anything I should be doing to prevent any longer term oxidation issues as well as anything that can be done to improve the appearance (having done this, I can attest that it now looks far worse than if I had just left the residue alone. The good news is that I only did this on the back of the board, the front is still pristine.)P.S. one minor silkscreen / doc bug: both reference removing JP1 when S3 is installed. Shouldn’t that be JP5?November 24, 2013 at 1:39 am #21549Windell OskayKeymaster
In our experience what happens when you wash a board with alcohol is that it partly dissolves the remaining solder flux, and spreads it around in a thin, sticky, sometimes white and flaky, but all-around awful layer that remains when the alcohol evaporates. If you didn’t leave it soaking for a long time, my best guess would be that the finish isn’t actually damaged, so much as covered under a thin layer of thinned solder flux, which can be removed with great patience or a professional-grade flux remover.Unless you’re using flux that *requires* removal or you are willing to pick up some solder flux, your best bet is probably to just hide the backside, and hope that no one asks to see– it shouldn’t be harmful.And on that bug: Yep, you’re totally right. That jumper used to be called JP1. Somehow, you’re the first person to notice this after a couple of years, and a surprisingly large number of Peggy 2 kits out there!November 24, 2013 at 11:15 am #21550dnewmanParticipant
Out of curiosity, what sort of isopropyl alcohol did you use? The 30/70 (alc/water) from the store, the less often seen 90/10, or 100% pure isopropyl alcohol? Companies such as Digikey and Mouser sell the 100% (well, 99.9%) pure stuff and it works tolerably well provided the solder had an ammenable-to-cleanup flux. The 30/70 stuff leaves a mess; I’ve never tried the 90/10 myself. What works best for me is to use solders with “no-clean” fluxes and to just not worry about it.November 24, 2013 at 11:30 am #21551
With a fresh pair of eyes, it looks like that’s exactly what happened: the finish is still there under a gross layer of gunk. I assume that’s what also dulled to solder joints so glad to hear that I only made a mess and didn’t do any damage.No biggie on the jumper (the docs *show* the right jumper and with S3 included in the kit probably very few people actually use it), just thought you’d want to know.I’m quite pleased with the kit: very well done and high quality. Looking forward to having fun playing with it.November 24, 2013 at 11:35 am #21552
dnewman: it was 91% and I used rosin core solder. My mistake (aside from attempting to clean it at all) may have been rinsing with water as opposed to wiping clean. I was assuming that the alcohol was more completely dissolving the flux as opposed to just smearing it around.EvilMadScience probably deserves some of the blame for making a PCB that I wanted to keep pretty :-)November 24, 2013 at 11:52 am #21553dnewmanParticipant
Personally, I don’t even try to clean black PCBs. They’re like a black finish on a car: anything I do shows, no matter how careful I am. Unfortunately, I don’t have a good solder recommendation as I stocked up a few years back on solder and what I’m using (quite successfully) is no longer available. But look for the non-clean varieties.If you go to, say, Digikey, you can actually search “solder no-clean” and turn up both leaded and unleaded solders. Digikey uses the phrase “no-clean” in their descriptions; e.g., “SOLDER NO-CLEAN 21AWG 63/37 1LB”.
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