Electronics > Beginners
Doesn't happen every day.. IC package destroyed while hot air soldering.
Ian.M:
Google: JEDEC bakeout
Sub 100°C the bakeout times can be *very* long e.g. 10 days for a 4.5mm thick package at 90°C & maintained <5% RH. At 125°C, the max bakeout time is a far more reasonable 48H.
A DIY oven for the purpose of baking out small quantities of loose parts could be as simple as a 40W incandescent light bulb in a high temperature holder mounted in a tin can with a ring of holes round the edge of the base for airflow, then a shallow aluminum tray, to hold the chips suspended above the bulb, with space for air circulation at the edge, and a bonded on thermocouple for temperature control, a lid with a vent to control the air-flow due to convection, and a programmable temperature controller capable of following a temperature profile, controlling the bulb power via a TRIAC. PID proportional control would be preferable. The can exterior and the lid should be thermally insulated.
If the components cant withstand a 125°C bakeout, then you'd need something fancier, with a drier on its incoming air. For components of uncertain provenance, I would suggest holding at 95°C long enough to significantly reduce the moisture level before the 125°C bakeout.
JPortici:
--- Quote from: RoGeorge on September 04, 2018, 07:40:26 pm ---Look at the bright side, you just found a new method to instantly decap chips without nasty chemicals! ;D
Can you take a photo of the decapped die under microscope, please?
--- End quote ---
wish i had one.. I actually forgot to ask my father if he has one at his lab (he's a chemist)
the most i can zoom in is with the crappy usb microscope i used above
HwAoRrDk:
According to the Digikey website, the MCP16311 is classified as Moisture Sensitivity Level (MSL) 3, which is only 168 hours, or 7 days. Sounds like moisture exposure could indeed be a culprit.
Eka:
--- Quote from: mcinque on September 04, 2018, 08:05:20 pm ---
--- Quote from: Benta on September 04, 2018, 12:09:21 pm ---Yep, moisture popcorning. You might be able to save them by baking.
--- End quote ---
I heard the baking should be very long (i.e. 90°C for 24h), don't know if it's right.
have you had any experience or maybe do you have any time/temperature combination to suggest?
--- End quote ---
It can even be many days or weeks. All depends on the package. Go read to the specifications sheet for that chip to see what is recommended for that package.
westfw:
I didn't realize that moisture would end up being a problem with "hand" soldering of SMT components :-(I knew it was an issue with full industrial reflow equipment...)
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