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From: Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>
Newsgroups: sci.electronics.design
Subject: Re: Operating temperature derating
Date: Mon, 3 Jun 2024 15:52:20 -0000 (UTC)
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Don Y <blockedofcourse@foo.invalid> wrote:
> Presumably, one should feel comfortable using a device at the
> published operating temperature extremes "forever".
> 
> But, what sort of derating likely went into that specification
> in the first place?  Sad another way, how much *beyond* those
> limits might want suspect you could operate the device?
> 
> 

Varies by device and package, unfortunately.
 
For example, running a plastic package above its glass transition will make
the epoxy creep due to thermal expansion. There’s nothing much to make it
creep back again on cooling. Cycles of that will eventually create voids,
break bond wires, and so on. 

Clive, previously Syd, will have lots more. 

Cheers 

Phil Hobbs 
-- 
Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /
Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics