rosek44•2mo agoProlific Poster

Took me 5 years to realize I was cleaning flux wrong with isopropyl alcohol.

I used to just dab at solder joints with a q-tip and 91% alcohol, leaving that white sticky film everywhere. Then a guy at a repair meetup in Portland told me to switch to 99% and use a stiff brush instead of dabbing. Anybody else find out the hard way that lower percentage alcohol just makes things worse on boards?

3 comments

3 Comments

noah_chen172mo ago

91% is basically useless, it leaves behind too much water and flux residue. 99% and a stiff brush is the only way to go for clean boards. Learned that one the hard way too after years of sticky messes.

taylorhunt1mo ago

Huh, I've actually had the opposite experience. 91% works fine for me if I let it sit for a minute before scrubbing. The extra water evaporates quick enough with compressed air or just letting the board dry overnight. Never had a sticky board issue unless I was lazy and didn't agitate the flux enough. 99% dries too fast sometimes and leaves that white crusty residue if you're not careful.

andrew8542mo ago

Man, I've been there. In my experience a quick dry brush after 91% makes a huge difference.