[time-nuts] Distribution amp - Use a video amp unit ?
shalimr9 at gmail.com
shalimr9 at gmail.com
Mon Mar 26 19:20:44 UTC 2012
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.
Sent from my BlackBerry Wireless thingy while I do other things...
From: ALAN MELIA <alan.melia at btinternet.com>
Sender: time-nuts-bounces at febo.com
Date: Mon, 26 Mar 2012 14:27:39
To: Discussion of precise time and frequency measurement<time-nuts at febo.com>
Reply-To: Discussion of precise time and frequency measurement
<time-nuts at 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
--- On Mon, 26/3/12, David C. Partridge <david.partridge at perdrix.co.uk> wrote:
> From: David C. Partridge <david.partridge at perdrix.co.uk>
> Subject: Re: [time-nuts] Distribution amp - Use a video amp unit ?
> To: "'Discussion of precise time and frequency measurement'" <time-nuts at 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.
> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com]
> On Behalf Of Peter Gottlieb
> Sent: 26 March 2012 13:50
> To: time-nuts at 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?
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