Built an IC this weekend and am not sure how to be sure it is clean enough.
I wiped it down with dish soap and boiled it, but still had some tarnish and dark spots on the copper. I attacked it with Barkeerpers Friend and a toothbrush and got it looking very clean and shiny. Probably spent more time cleaning it than I did building it. The toothbrush bristles are black now.
But once it dried, some dark spots reappeared. Not as many, but they are still there.
Is it clean enough?