I have often seen (don't ask me how) silicon diodes getting so hot that they
unsolder themselves from the board and fall at the bottom of the equipment
enclosure, yet they work fine after the fact even though they don't look so
good.
I have been tempted to solder them back in in more than one occasion...
I have not had it happen with an smd part yet, but its just a matter of time.
Didier KO4BB
Sent from my BlackBerry Wireless thingy while I do other things...
-----Original Message-----
From: ALAN MELIA <alan.me...@btinternet.com>
Sender: time-nuts-boun...@febo.com
Date: Mon, 26 Mar 2012 14:27:39
To: Discussion of precise time and frequency measurement<time-nuts@febo.com>
Reply-To: Discussion of precise time and frequency measurement
<time-nuts@febo.com>
Subject: Re: [time-nuts] Distribution amp - Use a video amp unit ?
Si juctions are formed at temps of 1000C or more. Thermal failure is more
likely to be due to alloying of metal contact areas. I used to lifetest
transistors up to 360C for 20 hours with power applied!! and anything up to 6
months at 200C. You cant get those temps with plastic encalsulations though
glass (double dummet) diodes will stand 300C easily
Alan
G3NYK
--- On Mon, 26/3/12, David C. Partridge <david.partri...@perdrix.co.uk> wrote:
> From: David C. Partridge <david.partri...@perdrix.co.uk>
> Subject: Re: [time-nuts] Distribution amp - Use a video amp unit ?
> To: "'Discussion of precise time and frequency measurement'"
> <time-nuts@febo.com>
> Date: Monday, 26 March, 2012, 14:02
> An Si junction can tolerate pretty
> high temperatures for a short while, or even a long while -
> Bob Pease reported having had a component sat on the hot end
> of a soldering iron for about 24 hours and still working
> afterwards ...
>
> I've never seen a description of how they make those glass
> cased parts - I guess speed is important.
>
> Dave
> -----Original Message-----
> From: time-nuts-boun...@febo.com
> [mailto:time-nuts-boun...@febo.com]
> On Behalf Of Peter Gottlieb
> Sent: 26 March 2012 13:50
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] Distribution amp - Use a video amp
> unit ?
>
> how are glass cased
> diodes made? Wouldn't the
> temperatures needed to form the glass and
> seal it to the leads destroy the silicon
> junction being put inside?
> Peter
>
>
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