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Weller WTCPT tip not hot enough

E

Eeyore

Jan 1, 1970
0
Arfa said:
Christ knows Graham ! I was about 18 at the time and probably about the only
one in the workshop who was reasonably comfortable with the new fangled
transistors ...

Thinking about it, the leads went E-B-Scr-space-C. It was probably one of
those fortuitous 'mistakes' where I was measuring the collector voltage, and
the meter probe slipped ...

Unlike me designing power amps where a similar slip tends to result in a lot of
magic smoke being let out.

Graham
 
E

Eeyore

Jan 1, 1970
0
N said:
Some of the bad joints i've seen in the last few years, you just do not come
across with leaded solder. And we're talking about kit only a year or two
old. eg totally unstressed (in temperature terms but subjected to vibration)
1/3 watt resistors (so no heatsinking at production) that you can pull out
of the "solder" joint by finger force.

Vibration is the killer with lead-free. Never mind the tin whiskers.

But did you also know about tin pest ? I have no idea how much the temperature
is affected by the copper (and silver for the rich) in lead-free but the Japs
also use bismuth IIRC.

" At 13.2 degrees Celsius (about 56 degrees Fahrenheit) and below, pure tin
transforms from the (silvery, ductile) allotrope of ?-modification white tin to
brittle, ?-modification grey tin. Eventually it decomposes into powder, hence
the name tin pest.

The decomposition will catalyze itself, which is why the reaction seems to speed
up once it starts; the mere presence of tin pest leads to more tin pest. Tin
objects at low temperatures will simply disintegrate. "
http://en.wikipedia.org/wiki/Tin_pest

Graham
 
N

N_Cook

Jan 1, 1970
0
Eeyore said:
Vibration is the killer with lead-free. Never mind the tin whiskers.

But did you also know about tin pest ? I have no idea how much the temperature
is affected by the copper (and silver for the rich) in lead-free but the Japs
also use bismuth IIRC.

" At 13.2 degrees Celsius (about 56 degrees Fahrenheit) and below, pure tin
transforms from the (silvery, ductile) allotrope of ?-modification white tin to
brittle, ?-modification grey tin. Eventually it decomposes into powder, hence
the name tin pest.

The decomposition will catalyze itself, which is why the reaction seems to speed
up once it starts; the mere presence of tin pest leads to more tin pest. Tin
objects at low temperatures will simply disintegrate. "
http://en.wikipedia.org/wiki/Tin_pest

Graham

In the situation where you can just pull a component from a board, not
desoledered, it is sometimes possible to see a grey powdery surface to the
component, suggestive of tin-pest.

And for using tin tinned new RoHS components destined for both old boards
and Pb-Sn solder or new boards and silver solder, burr the tin off with a
"diamond" cintride burr on a Dremmel, before tinning with the intended
solder. A solid layer of tin is asking for trouble - turn to dust tin-pest.
 
E

Eeyore

Jan 1, 1970
0
N_Cook said:
Eeyore wrote
come across with leaded solder. And we're talking about kit only a year or
two old. eg totally unstressed (in temperature terms but subjected to
vibration) 1/3 watt resistors (so no heatsinking at production) that you can
pull
out of the "solder" joint by finger force.
temperature is affected by the copper (and silver for the rich) in lead-free
but the
Japs also use bismuth IIRC.
tin transforms from the (silvery, ductile) allotrope of beta-modification
white
tin to brittle, alpha-modification grey tin. Eventually it decomposes into
powder,
hence the name tin pest.

These phase changes are called allotropes.

In the situation where you can just pull a component from a board, not
desoledered, it is sometimes possible to see a grey powdery surface to the
component, suggestive of tin-pest.

No surprise. A guitar amp kept in the garage will see those temps.

And for using tin tinned new RoHS components destined for both old boards
and Pb-Sn solder or new boards and silver solder, burr the tin off with a
"diamond" cintride burr on a Dremmel, before tinning with the intended
solder. A solid layer of tin is asking for trouble - turn to dust tin-pest.

And whiskers.

The military etc are doing an enhanced version of what you describe.

Graham
 
E

Eeyore

Jan 1, 1970
0
N said:
Its a time-temp-effect thing, must be less than 13.2 C to make any
appearance

How cold does the electronics in your car get in winter ?

Graham
 
N

N_Cook

Jan 1, 1970
0
Eeyore said:
These phase changes are called allotropes.



No surprise. A guitar amp kept in the garage will see those temps.

tin-pest.

And whiskers.

The military etc are doing an enhanced version of what you describe.

Graham


Do you know of a precise term, military or civil, for the process of
mechanical (or other method) removal of full tin tinning of component legs,
prior to use ?

With that pic of tin-pested cap I should have said that the solder joints
otherwise looked normal, only this surface layer tinning of the pin had
transformed to grey.
 
A

Arfa Daily

Jan 1, 1970
0
Eeyore said:
Unlike me designing power amps where a similar slip tends to result in a
lot of
magic smoke being let out.

Graham

Oh I had to work on them too ! Our company was responsible for background
music machines that were rented out ro shops etc. They used a sort of
cassette tape that was endless (!) in that it wound off the centre and back
on to the outside. Bit like an 8 track mechanism, but only had four tracks,
as I recall. Anyways, they had a bloody great amplifier built into them,
based on 2N3055s. Being an early design, there was no protection or bias
stabilization, and you only had to bring a 20k / volt meter near to some
points to get them to run away, releasing their magic smoke ... Happy days.
It's back when engineers learnt the business properly d:~}

Arfa
 
A

Arfa Daily

Jan 1, 1970
0
Now, I have a confession to make. When I started my current job 9
years ago, they told me they were switching to lead free solder. I
tried some of it at that time and it seemed fine. In the course of
this conversation I realized that I had no idea exactly what version
of lead-free we were using, so today I went into our shop and looked
at one of the spools, since I usually just pull off a few feet to take
back to my office where my bench is. What I found was spools of 60/40
tin/lead. I don't know how long that's been in use here, or if they
ever bought any more of the Rohs solder.

So at this point I have to admit that it's possible that I've been
mistaken for the past 9 years and I may have almost no Rohs soldering
experience. I apologize for my statements to the contrary. It now
seems clear why my "experience" with Rohs solder seemed to be so
positive. I'll try to find some actual Rohs to try.

I DO know that my previous workplace HAS made the switch to Rohs. I
still have friends there and it is a manufacturing environment. One of
those friends is one of their electrical engineers, so I'll make a
point of asking him how that changeover went and whether it has given
them any continuing problems.

Maybe I'll find that they went to 800 F tips, or maybe not.

-

No problem Jim, and it's nice to know that there are still people out there
honest enough to admit to such a situation ! I would be interested to know
what your friend's findings have been. If you once start working with
lead-free, you won't mistake it for leaded again ! The first thing you will
notice is why you suddenly don't seem able to make a shiny 'good' looking
joint any more. The stuff is also a lot 'stiffer' as it comes off the reel.
You might be surprised just how unpleasant the the stuff is to work with,
compared to 'proper' solder - and that goes for the aggressive flux fumes as
well. I wonder if your friend's place have put in additional bench
extraction / ventilation to ensure that he doesn't breath the stuff ...

Arfa
 
E

Eeyore

Jan 1, 1970
0
N said:
Here is a pic I took of what was probably tin pest.
Ignore the top pic as just a control showing normal silvery appearance of
pins after desoldering.

http://home.graffiti.net/diverse:graffiti.net/solder.jpg
The black cap, the top pin could be pulled out and the bottom one needed
desoldering.

I see. I misunderstood that the first time you posted that pic.

It is just about possible to see the all grey dusty covering to
the top pin. So that 100 percent tin layer eventually turns to the grey form
, expanding in the process. So like a weed growing through concrete it
forces the solder apart as well as in itself being non-condusctive.

Quite possible, that seems to be the process.

Graham
 
E

Eeyore

Jan 1, 1970
0
N_Cook said:
Do you know of a precise term, military or civil, for the process of
mechanical (or other method) removal of full tin tinning of component legs,
prior to use ?

I don't myself but there must be one since there's a market for it.

With that pic of tin-pested cap I should have said that the solder joints
otherwise looked normal, only this surface layer tinning of the pin had
transformed to grey.

I followed.

Graham
 
E

Eeyore

Jan 1, 1970
0
Arfa said:
in message

Oh I had to work on them too ! Our company was responsible for background
music machines that were rented out ro shops etc. They used a sort of
cassette tape that was endless (!) in that it wound off the centre and back
on to the outside. Bit like an 8 track mechanism, but only had four tracks,
as I recall. Anyways, they had a bloody great amplifier built into them,
based on 2N3055s. Being an early design, there was no protection or bias
stabilization, and you only had to bring a 20k / volt meter near to some
points to get them to run away, releasing their magic smoke ... Happy days.
It's back when engineers learnt the business properly d:~}

An, the days of 50uA meter movements. I do still have a small one and even found
a leather BT case designed for it on the local market.

Graham
 
E

Eeyore

Jan 1, 1970
0
N said:
Eeyore wrote

I see that in that article

Tin pest in Sn-0.5 wt.% Cu lead-free solder

Sliver solder does not supress tinpest, very much reduces its growth, but
not supressed like leaded solder.

I wonder just what we have waiting in store for us.

I had considered applying to the Comission for exemption for all goods
regularly subjected to vibration (such as used on location video and sound
recording) and which also might be subjected to freezing temps in use or
transit which could at least exempt pro A/V gear.

It seems one (at least one) loudspeaker manufacturer successfully got an
exemption on these grounds.

Graham
 
A

Arfa Daily

Jan 1, 1970
0
Eeyore said:
An, the days of 50uA meter movements. I do still have a small one and even
found
a leather BT case designed for it on the local market.

Graham

My good old AVO 8 Mk IV, which was originally issued to me as an apprentice
in about 1970, is still used every day. For 'resistance path' fault finding,
and semiconductor junction basic proving, it is still my instrument of
choice. There's something very comforting about seeing a needle swing over
to 'about the right place'.

I do of course have a raft of digital multimeters, both portable and bench,
and a full array of digital capacitance and ESR and so on meters for more
precise measurements where needed, but I find that a good quality analogue
meter still fits the bill for much general service work.

Arfa
 
A

Arfa Daily

Jan 1, 1970
0
Eeyore said:
I wonder just what we have waiting in store for us.

I had considered applying to the Comission for exemption for all goods
regularly subjected to vibration (such as used on location video and sound
recording) and which also might be subjected to freezing temps in use or
transit which could at least exempt pro A/V gear.


I guess that just about covers almost all electronic gear then ! Lets just
go for a complete ban on lead-free solder ! Power to the electronic
engineering industry !!!!!

Hmmmm. Video gear on location in freezing temperatures .... "So viewers,
after a 2 hour descent, we see the first signs of the Titanic coming into
view in remarkably sharp detail ... " Phhhttt !!! "Oh shit ..."
 
E

Eeyore

Jan 1, 1970
0
Arfa said:
"Eeyore" wrote


My good old AVO 8 Mk IV, which was originally issued to me as an apprentice
in about 1970, is still used every day. For 'resistance path' fault finding,
and semiconductor junction basic proving, it is still my instrument of
choice. There's something very comforting about seeing a needle swing over
to 'about the right place'.

And it's horrid seeing the movement protection fail !

I do of course have a raft of digital multimeters, both portable and bench,
and a full array of digital capacitance and ESR and so on meters for more
precise measurements where needed, but I find that a good quality analogue
meter still fits the bill for much general service work.

I only really use it where the mechanical averaging is useful, such as noise
measurements.

Otherwise it's my trusty Fluke 77. I think I've only ever seen one 'go wrong'
and it was repaired or replaced under warranty even though we didn't have the
invoice because they track the serial numbers themselves.

Graham
 
E

Eeyore

Jan 1, 1970
0
Arfa said:
"Eeyore" wrote

I guess that just about covers almost all electronic gear then ! Lets just
go for a complete ban on lead-free solder ! Power to the electronic
engineering industry !!!!!

Hmmmm. Video gear on location in freezing temperatures .... "So viewers,
after a 2 hour descent, we see the first signs of the Titanic coming into
view in remarkably sharp detail ... " Phhhttt !!! "Oh shit ..."

LOL !

The freezing often occurs overnight in the truck. Never mind road quality for
vibration getting it there.

Graham
 
E

Eeyore

Jan 1, 1970
0
N said:
It seems that if you produce kit and some of it, as little as 5 percent, is
used in medical/military/aeronautical/space, even if only in R&D/analysis
laboratories attached to any of those industries, then you can get a
derogation for all production. On the grounds that it is unreasonable to
force a company to run 2 parallel production lines.

Is this a specific ruling you've come across ? Certainly interesting.

Graham
 
O

Old TV Repairman

Jan 1, 1970
0
Arfa Daily said:
Oh I had to work on them too ! Our company was responsible for
background music machines that were rented out ro shops etc. They
used a sort of cassette tape that was endless (!) in that it wound
off the centre and back on to the outside. Bit like an 8 track
mechanism, but only had four tracks, as I recall. Anyways, they had
a bloody great amplifier built into them, based on 2N3055s. Being an
early design, there was no protection or bias stabilization, and you
only had to bring a 20k / volt meter near to some points to get them
to run away, releasing their magic smoke ... Happy days. It's back
when engineers learnt the business properly d:~}

Arfa
Hmmm...I used to be an apprentice at a company that manufactured
background music machines utilising those big cartridges. They sounded
bloody awful with violin music on - used to warble something chronic.
For test purposes us young lads recorded stuff like Jimi Hendrix on
them!

Roy
 
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