Yep that was me, we replace AEC on a cyclic basis, nominal 5 year max 10 year if stored, and not on just old boards, on all equipment that is important to safety or safe shutdown. Typically our biggest concern is the power supplies, we do reform our stored power supplies every 2 years then test them at 100% load for 24 hours, prior to returning them to storage. We recently went on a crusade to upgrade all of the old linear supplies to modern switchers, and just replace them every 5 years.
Pat
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Rex Waygood
Sent: Tuesday, August 14, 2012 9:03 AM
To: [log in to unmask]
Subject: Re: [TN] PCBA shelf life
Someone on the forum talked about replacing Aluminium Electrolytic Caps on 'old' pcbs during servicing. I think they were in the Nuclear Industry.
The caps may need forming before applying power even if you don't replace them.
Rex
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
Sent: 14 August 2012 16:31
To: [log in to unmask]
Subject: Re: [TN] PCBA shelf life
IMHO, if stored in a reasonably clean environment without special conditions, packed assemblies have an almost indefinite lifetime, especially with professional-quality components. I have, on several occasions, the last only this week, plugged in items 5-10 years old and they have worked perfectly every time. I would make one proviso, that the circuitry is neither ultra-high impedance (>10E12 ohms) or very sensitive to dielectric constant of the substrate.
Brian
On 14/08/2012 04:21, Ivan Feng wrote:
> Folks,
>
> Bare PCB has a shelf life depending on its surface finish, component like electrolytic capacitor and MSD devices also have defined shelf life.
> But for PCBA, how to define its shelf life? Is there any applicable standards?
>
> Any suggestions are welcomed.
>
> Regards
> Ivan
>
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