So I bought some stm32 chips to repair a 3d printer board. They were on the shelf in the bag with dessicant for 6 months, but the moisture detector strip shows under 60% moisture, but over 10% moisture. I need to bake them.
STM32 AN2639 Application Note:
The stm32 After opening a dry pack, soldering should be done within 24 hours. SMD products stored over the specified storage period need to be baked at 125 °C for 24 hours (under nitrogen atmosphere).
I can bake the chip at 125C for 24 hours, but "under ntirogen atmosphere" is a bit of a problem. I have read that the nitrogen is required because even at 125C the air could have as much as 20% humidity. That seems a bit high to me, but I don't have a hygrometer, so that's hard to verify.
What do you recommend for drying these chips? I was going to reflow them, but I think that's out at this point, I just need them OK for hand soldering or soldering with hot air (recommendations?). There's no pad underneath the chip, it's not bga, just smt.
Here's are some items that could be relevant in making a solution
I have a reflow oven (
https://hackaday.io/project/171619-not-just-a-reflow-oven )
dessicant
vacuum pump
3d printers with heated beds that could be used as a hot plate up to 120C or so
40cf nitrogen
My oven isn't airtight enough to run a nitrogen purge, but I could do something like find a small jar, put the dessicant in with a the chip, drill a small hole in the lid and bake in the oven. Or I could build a small vacuum chamber and run the vacuum pump. Anyone have thoughts or ideas?
Thanks!