I recently bought a PCB from someone that was created by
OSH Park. Other than the pictures online, this is the first board I've seen from them. Even though I didn't buy the PCB directly from OSH Park, it was very clean when I received it from the seller.
Anyway, after handling the board (with finger prints) and soldering all of the components, I decided to clean it with
99.9% pure isopropyl alcohol. I do this all the time with other PCB's. I use
Kim wipes, Q-tips, etc. and gently wipe the boards. I allow adequate time for drying. But for some reason, much of the board has a sticky residue left over which really has me puzzled. Oh, and yes, my hands were clean before I started...there are no obvious contaminants floating around and my house is smoke-free. :-)
My other boards don't have this problem. Plus, the bottle of alcohol I used was brand new...even had to break the seal on it so I don't believe it was contaminated.
Any ideas what this could be? I wouldn't think it's the purple solder mask OSH Park uses. I've read lots of good things about them.
The board works great. Just really puzzled why it is so much harder to clean than the hundreds of other boards I use.
** EDIT **
The flux makes sense. I just remembered that I cleaned the board BEFORE and after I soldered the components. I don't normally clean them before I solder them. Soldering the components more than likely burns off most of the flux which is why I never noticed it when I cleaned the other boards after. I didn't know that about IPA and flux. Learned something new today! Thanks.