I've seen comments here lately about chips having a shelf life beyond which they may not be reliable.
I have a bunch of LM3886, LM4562, LME49860 chips, (and others) that have been waiting to be used for upwards of ten years, maybe even more in some cases. They've been stored in the original tubes or static foam, in an area that is temp and humidity controlled.
Should I worry about using them now, or should they be replaced? Or if it is a potential problem, can they be baked or something to "rejuvenate" them?
I obviously don't want to try to use them in a project if they are no longer reliable.
Mike
I have a bunch of LM3886, LM4562, LME49860 chips, (and others) that have been waiting to be used for upwards of ten years, maybe even more in some cases. They've been stored in the original tubes or static foam, in an area that is temp and humidity controlled.
Should I worry about using them now, or should they be replaced? Or if it is a potential problem, can they be baked or something to "rejuvenate" them?
I obviously don't want to try to use them in a project if they are no longer reliable.
Mike
The concern revolves mostly around moisture ingress and package disintegration during [wave] soldering, or longer term internal corrosion.
Given the way you have stored them I would not expect there to be an particular issue.
Might want to use a good flux when soldering, tin oxide sometimes is a little recalcitrant at taking solder.
Given the way you have stored them I would not expect there to be an particular issue.
Might want to use a good flux when soldering, tin oxide sometimes is a little recalcitrant at taking solder.
Some of the black foam from the 70's and 80's degrades and turns into somethint that will eat the legs off the chips. I had a bunck of rare music synthesizer chips stored in black foam which was sealed in ziplock bags. To my dismay the foam had turned to black dust and the leads on the chips had crumbled, or disintegrated when I tried to clean the foam off. I soldered wires on the nubs of the pin remnants on one Mostek MY50240 chip and the chip itself was still alive.
I'm told the pink foam doesn't do that but all my chips from the 70's and early 80's are pretty much useless. If you have them stuck in black foam, you might want to put them in tubes or just a static bag.
I have a bunch of audio chips and mosfets that I got from the National and Motorola reps in the late 80's and 90's. All were stored in the tubes that they came in, and all are fine. I built a few projects with them over the years with no issues.....all worked and soldered fine.
No need to bake chip that will be hand soldered one pin at a time. Baking is usually only needed with large size SMD chips running through an autimated reflow oven where the temperature change is rather rapid and hits the whole chip at once.
We baked (slow cooked) every chip that had been stored outside the dry box for more than a day to prevent them from shattering, splitting open, or delaminating when soldered. We were however using an IR reflow oven in an automated process hot enough for lead free solder. Any chip left out of the dry box, even in the clean room might absorb enough moisture to decompose when reflowed.
I hand cooked plenty of SMD chips without an issue, but every once in a while we would get a batch that would go bad when soldered. Sometimes the damage was internal and only visible when X-rayed. One or two wire bonds would get ripped off due to an internal moisture bubble.
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