Zener diode failure mode.

[Rubicon]

Hello,

I'm wondering in what mode do zener diodes fail?
In short circuit mode or open mode?
I intend to use some in reverse bias as voltage regulators/clamps.

I take it resistors fail in short circuit mode when subjected to too
much voltage/current - go above their Wattage rating for too long.

Andrew.
Remove ZZ from E-Mail to contact me.

[Phil Allison]

"Rubicon" <ZZru...@netaccess.co.nz> wrote in message
news:3d15b3f5...@news.netaccess.co.nz...

>
> Hello,
>
> I'm wondering in what mode do zener diodes fail?
> In short circuit mode or open mode?

** Zeners give a brief flash of visible light when over-voltaged and then
go out forever.

They fail short and then die. RIP.

Regards, Phil

[John Larkin]

On Sun, 23 Jun 2002 11:51:29 GMT, ZZru...@netaccess.co.nz (Rubicon)
wrote:

Leaded zeners mainly fail shorted, at least the modern 'nailhead'
types that don't have wire bonds. A SOT-23 type zener does have bonds,
so can blow open after it shorts if enough current is available.

Resistors most often fail open or at least jump way up in resistance.
Carbon composition resistors can bake themselves to a low resistance
state, but carbon comps are hardly made any more. Surface-mount
resistors basicly always fail open, and in fact can make decent fuses.

I hooked a bunch of 0805 resistors across the AC line a while back.
Some just went 'bip' and opened, and some caught fire and *then*
opened.

John

[ziggy]

Thanks for your insights. I liked the 'bip' and fire parts! :o))

"John Larkin" <Jo...@0.com> wrote in message
news:5f5chu0poccvn106o...@4ax.com...

[Rubicon]

Yes - thankyou. Rude of me not to write so earlier.

Andrew.

[jpfiguei...@gmail.com]

They usually fail as a short circuit. Take a look at this:

https://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0ahUKEwjo3PCHvqTVAhUL1hQKHR-4A-UQFghCMAM&url=http%3A%2F%2Fdownload.21dianyuan.com%2Fdownload.php%3Fid%3D170219&usg=AFQjCNF8Ykl_XFTBvaztauJ86auj8OB7aQ&cad=rja

Regards,
João

[Ralph Mowery]

In article <d65e203c-447d-4d53...@googlegroups.com>,
jpfiguei...@gmail.com says...

Most common simiconductors fail as shorted unless there is enough
current to blow the cevice open.

[Ian Field]

"Ralph Mowery" <rmower...@earthlink.net> wrote in message
news:MPG.33e1328d...@news.east.earthlink.net...

And some dodgy and/or counterfeit rectifiers that crack in
two..................

[Pimpom]

Em domingo, 23 de junho de 2002 13:51:29 UTC+2, Rubicon escreveu:
>> Hello,
>>
>> I'm wondering in what mode do zener diodes fail?
>> In short circuit mode or open mode?
>> I intend to use some in reverse bias as voltage regulators/clamps.
>>
>> I take it resistors fail in short circuit mode when subjected to too
>> much voltage/current - go above their Wattage rating for too long.
>>
>> Andrew.
>> Remove ZZ from E-Mail to contact me.

Wrong presumption about resistors. During some 30 years of
repairing work, I came across just two resistors that failed
short. All the others failed open. Semiconductors, on the other
hand fail short more often than open, or have excessive leakage
in the reverse direction.

[Pimpom]

Just noticed that the OP asked the question on June 23, 2002!

[Ian Field]

"Pimpom" <Pim...@invalid.com> wrote in message
news:om42ff$s3p$1...@news.albasani.net...

Resistors of a certain type of construction can go low or short - sounds
like you've encountered about as many as I have.

[John Larkin]

Carbon comps can fail shorted, but they are rare these days. Film-type
resistors usually fail open.

I've had the metal-jacket military type wirewound resistors fail
shorted, from thermal cycling fatigue.


--

John Larkin Highland Technology, Inc trk

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com