Old Ge transistors and Whiskers...

C

Chris M. White

Guest
Hi,

Anyone know if NOS (old, but never used) germanium transistors are
prone to forming whiskers to the same extent as used ones? I\'m not
sure if it\'s a phenomenon which arises from the electrical potential
applied during the service life of the device or not. Anyone know?

Chris.
 
On Sunday, November 28, 2021 at 9:35:21 PM UTC-4, Chris M. White wrote:
Hi,

Anyone know if NOS (old, but never used) germanium transistors are
prone to forming whiskers to the same extent as used ones? I\'m not
sure if it\'s a phenomenon which arises from the electrical potential
applied during the service life of the device or not. Anyone know?
Click to expand...

I don\'t know for sure, but I\'ve never heard that metallic whiskers were grown by electrical potential. I believe it is just a metallurgical matter.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209
 
In article <ed720d84-43f7-4e79-8eb9-527ae3fc671bn@googlegroups.com>,
gnuarm.deletethisbit@gmail.com says...
Anyone know if NOS (old, but never used) germanium transistors are
prone to forming whiskers to the same extent as used ones? I\'m not
sure if it\'s a phenomenon which arises from the electrical potential
applied during the service life of the device or not. Anyone know?

I don\'t know for sure, but I\'ve never heard that metallic whiskers were grown by electrical potential. I believe it is just a metallurgical matter.
Click to expand...

I aagree. Some old GE comercial radios would do that in the tuned
cavities and there is no power in them.
 
On Monday, November 29, 2021 at 12:35:21 PM UTC+11, Chris M. White wrote:
Hi,

Anyone know if NOS (old, but never used) germanium transistors are
prone to forming whiskers to the same extent as used ones? I\'m not
sure if it\'s a phenomenon which arises from the electrical potential
applied during the service life of the device or not. Anyone know?

**See:
Click to expand...

https://nepp.nasa.gov/whisker/anecdote/af114-transistor/index.html

** Seems it\'s related to age, not usage.


....... Phil
 
On Monday, November 29, 2021 at 1:16:24 AM UTC-4, palli...@gmail.com wrote:
On Monday, November 29, 2021 at 12:35:21 PM UTC+11, Chris M. White wrote:
Hi,

Anyone know if NOS (old, but never used) germanium transistors are
prone to forming whiskers to the same extent as used ones? I\'m not
sure if it\'s a phenomenon which arises from the electrical potential
applied during the service life of the device or not. Anyone know?

**See:

https://nepp.nasa.gov/whisker/anecdote/af114-transistor/index.html

** Seems it\'s related to age, not usage.
Click to expand...

My understanding is these whiskers are very fragile requiring only a tiny current to remove them. It is mentioned on one of the NASA pages how measuring the short with a standard ohm meter is enough to clear the short. It seems the short would be cleared by the currents flowing in most circuits the devices would be used in. No?

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209
 
On 29/11/2021 22:42, Rick C wrote:
On Monday, November 29, 2021 at 1:16:24 AM UTC-4, palli...@gmail.com wrote:
On Monday, November 29, 2021 at 12:35:21 PM UTC+11, Chris M. White wrote:
Hi,

Anyone know if NOS (old, but never used) germanium transistors are
prone to forming whiskers to the same extent as used ones? I\'m not
sure if it\'s a phenomenon which arises from the electrical potential
applied during the service life of the device or not. Anyone know?

**See:

https://nepp.nasa.gov/whisker/anecdote/af114-transistor/index.html

** Seems it\'s related to age, not usage.

My understanding is these whiskers are very fragile requiring only a tiny current to remove them. It is mentioned on one of the NASA pages how measuring the short with a standard ohm meter is enough to clear the short. It seems the short would be cleared by the currents flowing in most circuits the devices would be used in. No?
Click to expand...

No. Murphy\'s law and all that. Often the circuit dows not supply enough
current to clear the short, and in other cases, a lot of current is
available and the whisker starts an arc that vapourises big important
parts of the equipment.

I\'ve seen quite a few whiskers, but so far always on very old (pre-1970)
equipment. I\'ve not yet seen any on RoHS compliant stuff. I wonder if it
is just that the whiskers grow slowly, or if they used worse kinds of
plating a long time ago.
 
On Sunday, November 28, 2021 at 9:35:21 PM UTC-4, Chris M. White wrote:
Hi,

Anyone know if NOS (old, but never used) germanium transistors are
prone to forming whiskers to the same extent as used ones? I\'m not
sure if it\'s a phenomenon which arises from the electrical potential
applied during the service life of the device or not. Anyone know?
Click to expand...

I didn\'t know tin whiskers had impacted the nuclear power industry. Seems, as is not uncommon, they didn\'t think events that affect other industries would impact them. The effect of tin whiskers was first documented in 1951 and satellites were lost due to tin whiskers as early as 1998. Medical implants were recalled in 1984 for tin whisker defects. Methods of mitigating tin whiskers were developed in 1974. Yet, it was allowed to impact the nuclear power industry directly right up to 2005. Right up until they had a reactor scram at Millstone, CT the nuclear industry believed they were immune from the effect or more accurately kept their head in the sand while other industries were hit by the issue.

No wonder the nuclear industry is not much trusted.

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209
 
On Monday, November 29, 2021 at 8:47:25 AM UTC-4, Chris Jones wrote:
On 29/11/2021 22:42, Rick C wrote:
On Monday, November 29, 2021 at 1:16:24 AM UTC-4, palli...@gmail.com wrote:
On Monday, November 29, 2021 at 12:35:21 PM UTC+11, Chris M. White wrote:
Hi,

Anyone know if NOS (old, but never used) germanium transistors are
prone to forming whiskers to the same extent as used ones? I\'m not
sure if it\'s a phenomenon which arises from the electrical potential
applied during the service life of the device or not. Anyone know?

**See:

https://nepp.nasa.gov/whisker/anecdote/af114-transistor/index.html

** Seems it\'s related to age, not usage.

My understanding is these whiskers are very fragile requiring only a tiny current to remove them. It is mentioned on one of the NASA pages how measuring the short with a standard ohm meter is enough to clear the short. It seems the short would be cleared by the currents flowing in most circuits the devices would be used in. No?

No. Murphy\'s law and all that. Often the circuit dows not supply enough
current to clear the short, and in other cases, a lot of current is
available and the whisker starts an arc that vapourises big important
parts of the equipment.

I\'ve seen quite a few whiskers, but so far always on very old (pre-1970)
equipment. I\'ve not yet seen any on RoHS compliant stuff. I wonder if it
is just that the whiskers grow slowly, or if they used worse kinds of
plating a long time ago.
Click to expand...

Mostly they used tin-lead solder in the good old days which is not subject to tin whiskers. RoHS compliant, lead free solder is exactly the material that grows tin whiskers. Seems pure tin coatings have also been used though. The can around a pacemaker was the cause of a recall when the can maker messed up and shipped a batch that was tin plated. The company using the cans did not test the coating.

What parts of pre-1970 equipment developed tin whiskers? Was it non-electrical components?

--

Rick C.

-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209
 
On Mon, 29 Nov 2021 04:56:28 -0800 (PST), Rick C
<gnuarm.deletethisbit@gmail.com> wrote:

On Monday, November 29, 2021 at 8:47:25 AM UTC-4, Chris Jones wrote:
On 29/11/2021 22:42, Rick C wrote:
On Monday, November 29, 2021 at 1:16:24 AM UTC-4, palli...@gmail.com wrote:
On Monday, November 29, 2021 at 12:35:21 PM UTC+11, Chris M. White wrote:
Hi,

Anyone know if NOS (old, but never used) germanium transistors are
prone to forming whiskers to the same extent as used ones? I\'m not
sure if it\'s a phenomenon which arises from the electrical potential
applied during the service life of the device or not. Anyone know?

**See:

https://nepp.nasa.gov/whisker/anecdote/af114-transistor/index.html

** Seems it\'s related to age, not usage.

My understanding is these whiskers are very fragile requiring only a tiny current to remove them. It is mentioned on one of the NASA pages how measuring the short with a standard ohm meter is enough to clear the short. It seems the short would be cleared by the currents flowing in most circuits the devices would be used in. No?

No. Murphy\'s law and all that. Often the circuit dows not supply enough
current to clear the short, and in other cases, a lot of current is
available and the whisker starts an arc that vapourises big important
parts of the equipment.

I\'ve seen quite a few whiskers, but so far always on very old (pre-1970)
equipment. I\'ve not yet seen any on RoHS compliant stuff. I wonder if it
is just that the whiskers grow slowly, or if they used worse kinds of
plating a long time ago.

Mostly they used tin-lead solder in the good old days which is not subject to tin whiskers. RoHS compliant, lead free solder is exactly the material that grows tin whiskers. Seems pure tin coatings have also been used though. The can around a pacemaker was the cause of a recall when the can maker messed up and shipped a batch that was tin plated. The company using the cans did not test the coating.

What parts of pre-1970 equipment developed tin whiskers? Was it non-electrical components?
Click to expand...

Certain products were more affected than others. IIRC the AF117 found
in large numbers of early transistor radios was particularly prone to
growing whiskers. A typical remedy involves tying EBC together and
then zapping a HV cap between them and the screen. Use enough voltage
and you can pretty much vaporise the whiskers. They will grow back
again in time, but this method usually \'fixes\' the problem for several
years.
--

\"In one word, you reproach us with intending to do away with your property.
Precisely so; that is just what we intend.\"

- The Communist Manifesto, Marx & Engels.
 
Chris Jones <lugnut808@spam.yahoo.com> wrote:
On 29/11/2021 22:42, Rick C wrote:
On Monday, November 29, 2021 at 1:16:24 AM UTC-4, palli...@gmail.com wrote:
On Monday, November 29, 2021 at 12:35:21 PM UTC+11, Chris M. White wrote:
Hi,

Anyone know if NOS (old, but never used) germanium transistors are
prone to forming whiskers to the same extent as used ones? I\'m not
sure if it\'s a phenomenon which arises from the electrical potential
applied during the service life of the device or not. Anyone know?

**See:

https://nepp.nasa.gov/whisker/anecdote/af114-transistor/index.html

** Seems it\'s related to age, not usage.

My understanding is these whiskers are very fragile requiring only a tiny current to remove them. It is mentioned on one of the NASA pages how measuring the short with a standard ohm meter is enough to clear the short. It seems the short would be cleared by the currents flowing in most circuits the devices would be used in. No?


No. Murphy\'s law and all that. Often the circuit dows not supply enough
current to clear the short, and in other cases, a lot of current is
available and the whisker starts an arc that vapourises big important
parts of the equipment.

I\'ve seen quite a few whiskers, but so far always on very old (pre-1970)
equipment. I\'ve not yet seen any on RoHS compliant stuff. I wonder if it
is just that the whiskers grow slowly, or if they used worse kinds of
plating a long time ago.
Click to expand...

I\'ve seen them on post year 2000 equipment that wasn\'t RoHS. They\'re real
odd and far too small to play with. Even true needle point meter probes
are too big.
 
In article <92d95e01-02d7-41cb-b8fe-cc6251132d3bn@googlegroups.com>,
gnuarm.deletethisbit@gmail.com says...
What parts of pre-1970 equipment developed tin whiskers? Was it non-electrical components?
Click to expand...

Some if it was the tin or tin plated shielding between parts. The GE
MASTR transceivers did that in the antenna circuits before they went to
a different material.
 
On 11/29/2021 7:47 AM, Chris Jones wrote:
On 29/11/2021 22:42, Rick C wrote:
On Monday, November 29, 2021 at 1:16:24 AM UTC-4, palli...@gmail.com
wrote:
On Monday, November 29, 2021 at 12:35:21 PM UTC+11, Chris M. White
wrote:
Hi,

Anyone know if NOS (old, but never used) germanium transistors are
prone to forming whiskers to the same extent as used ones? I\'m not
sure if it\'s a phenomenon which arises from the electrical potential
applied during the service life of the device or not. Anyone know?

**See:

https://nepp.nasa.gov/whisker/anecdote/af114-transistor/index.html

** Seems it\'s related to age, not usage.

My understanding is these whiskers are very fragile requiring only a
tiny current to remove them.  It is mentioned on one of the NASA pages
how measuring the short with a standard ohm meter is enough to clear
the short.  It seems the short would be cleared by the currents
flowing in most circuits the devices would be used in.  No?


No. Murphy\'s law and all that. Often the circuit dows not supply enough
current to clear the short, and in other cases, a lot of current is
available and the whisker starts an arc that vapourises big important
parts of the equipment.

I\'ve seen quite a few whiskers, but so far always on very old (pre-1970)
equipment. I\'ve not yet seen any on RoHS compliant stuff. I wonder if it
is just that the whiskers grow slowly, or if they used worse kinds of
plating a long time ago.
Click to expand...

I got my hands on a number of NOS ~60 y/o germanium transistors a number
of years back from a a ham\'s estate, they were all junk with shorts
between various leads.
 
On Monday, November 29, 2021 at 4:56:33 AM UTC-8, gnuarm.del...@gmail.com wrote:
On Monday, November 29, 2021 at 8:47:25 AM UTC-4, Chris Jones wrote:

I\'ve seen quite a few whiskers, but so far always on very old (pre-1970)
equipment. I\'ve not yet seen any on RoHS compliant stuff. I wonder if it
is just that the whiskers grow slowly, or if they used worse kinds of
plating a long time ago.
Mostly they used tin-lead solder in the good old days which is not subject to tin whiskers. RoHS compliant, lead free solder is exactly the material that grows tin whiskers. Seems pure tin coatings have also been used though. The can around a pacemaker was the cause of a recall when the can maker messed up and shipped a batch that was tin plated. The company using the cans did not test the coating.

What parts of pre-1970 equipment developed tin whiskers? Was it non-electrical components?
Click to expand...

It happens in formed steel parts (maybe even Invar as used in frit-seal DIP packages) when the
steel gets a tin-plate finish. Food-grade tin plate, presumably, was the rule back half a century ago,
and tin is notorious for having unstable crystal structure (look for \'tin pest\' on YouTube). Tin/lead
and tin/silver/copper are relatively whisker-free, but it\'s only tin/lead that has a long field trial history,

Early steel deep-drawn transistor cans are a prime tin whisker demo site.
 
On 29/11/2021 23:56, Rick C wrote:
On Monday, November 29, 2021 at 8:47:25 AM UTC-4, Chris Jones wrote:
On 29/11/2021 22:42, Rick C wrote:
On Monday, November 29, 2021 at 1:16:24 AM UTC-4, palli...@gmail.com wrote:
On Monday, November 29, 2021 at 12:35:21 PM UTC+11, Chris M. White wrote:
Hi,

Anyone know if NOS (old, but never used) germanium transistors are
prone to forming whiskers to the same extent as used ones? I\'m not
sure if it\'s a phenomenon which arises from the electrical potential
applied during the service life of the device or not. Anyone know?

**See:

https://nepp.nasa.gov/whisker/anecdote/af114-transistor/index.html

** Seems it\'s related to age, not usage.

My understanding is these whiskers are very fragile requiring only a tiny current to remove them. It is mentioned on one of the NASA pages how measuring the short with a standard ohm meter is enough to clear the short. It seems the short would be cleared by the currents flowing in most circuits the devices would be used in. No?

No. Murphy\'s law and all that. Often the circuit dows not supply enough
current to clear the short, and in other cases, a lot of current is
available and the whisker starts an arc that vapourises big important
parts of the equipment.

I\'ve seen quite a few whiskers, but so far always on very old (pre-1970)
equipment. I\'ve not yet seen any on RoHS compliant stuff. I wonder if it
is just that the whiskers grow slowly, or if they used worse kinds of
plating a long time ago.

Mostly they used tin-lead solder in the good old days which is not subject to tin whiskers. RoHS compliant, lead free solder is exactly the material that grows tin whiskers. Seems pure tin coatings have also been used though. The can around a pacemaker was the cause of a recall when the can maker messed up and shipped a batch that was tin plated. The company using the cans did not test the coating.

What parts of pre-1970 equipment developed tin whiskers? Was it non-electrical components?
Click to expand...

I\'ve had transistor cans from the 1960s, and a relay from a WWII radio
that had lots of whiskers on its housing, and I think some other parts
that I have forgotten. All electronic components, but usually parts of
the component that don\'t have any electronic function.
 
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