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Flux viscosity difference between 2019 and 2025 batches
I keep a log of every rework job I do, and I noticed something odd going back through it. In 2019 I was using the same brand of no-clean flux pen I buy now, but the tackiness and spread are completely different. Old flux would hold components in place for a full minute before reflow. New stuff dries almost instantly, which is fine for tiny SMD work but a pain when I'm positioning a 48-pin QFP. I think the formula changed around 2022, but the label still says the same part number. A fellow tech in Austin told me he saw the same shift with his stock, so it's not just a bad batch. Has anyone else compared their old flux pens to new ones and noticed this? Or am I chasing a variable that doesn't matter once you hit the hot air gun?
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henry_singh6614d ago
Wait, the flux dries before you can even seat a 48-pin QFP? That is wild to me because holding a big chip in place is like half the reason I even reach for the pen in the first place. I have a couple of the old ones rolling around in a drawer and now I want to dig them out just to compare. If the tack time really dropped from a full minute down to seconds, that is not a small tweak, that is a whole different product wearing the same label. What gets me is they kept the part number the same so you have no way to tell which version you are buying. Same thing happened with the lead-free solder I used to run, they changed the flux core and never said a word. Your log is probably the most useful thing in this whole thread, most of us just toss the old pen and blame ourselves when stuff slides around.
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