Update: That guy who told me to quit using flux pens was right

I used to swear by flux pens for small board work. Then a repair shop owner in Denver watched me reflow a connector and said 'you're just pushing corrosion deeper with those things.' I didn't believe him until I looked under a scope at 40x and saw the residue trail. Switched to a syringe with gel flux and my joints actually flow right now. Has anyone else found flux pens cause more problems than they solve?

2 comments

2 Comments

lucas_carr2418d agoMost Upvoted

Man those blue pens got me too for a while. I actually switched because I kept getting these weird intermittent shorts on some tiny qfn packages and couldn't figure out why. Cleaned the board with ipa and hit it with a scope and saw all this crusty residue hiding under the components. The syringe gel takes a little getting used to but once you figure out how much to put down it's way more predictable. My reworks have been holding up way better too, especially on boards that see any kind of humidity or temp changes.

hart.taylor18d ago

Wait, are you telling me those little blue pens I've been using for years are actually doing more harm than good? I used to think they were perfect for quick fixes because they kept things clean without dripping everywhere. But now I'm thinking about all those boards I worked on and feeling kinda stupid. I saw a video once where a guy showed flux residue trapping moisture under components over time, and it made me start paying attention. That syringe method sounds like a pain to get used to but the results you're describing are hard to ignore. Have you noticed a difference in how long your repairs hold up after switching?