Discussion:
Solder guard material
(too old to reply)
d***@gmail.com
2014-02-09 04:16:52 UTC
Permalink
Maybe some electronics guru could
help resolving this issue. A friend
of mine who is interested in fabricating
1, 2 layer PCBs says that typical solder
guard(the green stuff) on PCBs that
has the glossy finish, is nitrocellulose
lacquer. As far as I know nitrocellulose
lacquer is toxic. If so, what is the
material used for PCB solder guard ? Any
hints. suggestions would be of great
help. Thanks in advance for your help.
gregz
2014-02-09 08:05:38 UTC
Permalink
Post by d***@gmail.com
Maybe some electronics guru could
help resolving this issue. A friend
of mine who is interested in fabricating
1, 2 layer PCBs says that typical solder
guard(the green stuff) on PCBs that
has the glossy finish, is nitrocellulose
lacquer. As far as I know nitrocellulose
lacquer is toxic. If so, what is the
material used for PCB solder guard ? Any
hints. suggestions would be of great
help. Thanks in advance for your help.
It should not be shiny. Lacquer is dull unless it's buffed. I'm sure I got
dust in my lungs from sanding old cars. What isn't toxic ?

Greg
John Fields
2014-02-09 08:18:36 UTC
Permalink
Post by d***@gmail.com
Maybe some electronics guru could
help resolving this issue. A friend
of mine who is interested in fabricating
1, 2 layer PCBs says that typical solder
guard(the green stuff) on PCBs that
has the glossy finish, is nitrocellulose
lacquer. As far as I know nitrocellulose
lacquer is toxic. If so, what is the
material used for PCB solder guard ? Any
hints. suggestions would be of great
help. Thanks in advance for your help.
---
Google "solder mask"

John Fields
Adrian Tuddenham
2014-02-09 10:40:28 UTC
Permalink
Post by d***@gmail.com
Maybe some electronics guru could
help resolving this issue. A friend
of mine who is interested in fabricating
1, 2 layer PCBs says that typical solder
guard(the green stuff) on PCBs that
has the glossy finish, is nitrocellulose
lacquer. As far as I know nitrocellulose
lacquer is toxic. If so, what is the
material used for PCB solder guard ? Any
hints. suggestions would be of great
help. Thanks in advance for your help.
I don't think you will find that nitrocellulose is toxic, although there
may be other toxins in the lacquer and, of course, any form of dust can
be harmful.

The big danger is that cellulose nitrate (nitrocellulose) is potentially
explosive. For many years now, in all applications except record
mastering and some analysis laboratory processes, it has been replaced
by cellulose acetate.
--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
Fred Abse
2014-02-09 16:26:23 UTC
Permalink
Post by Adrian Tuddenham
The big danger is that cellulose nitrate (nitrocellulose) is potentially
explosive. For many years now, in all applications except record
mastering and some analysis laboratory processes, it has been replaced by
cellulose acetate.
In the 19th, and early 20th centuries, men wore collars made out of the
stuff (Celluloid). Picture the scene; man wearing celluloid collar leans
over gas light jet, to light a cigar. POOF!

Photographers would occasionally use a celluloid collar when they ran out
of flash powder.

AKA guncotton. Evil stuff. Naval guns used it as a propellant, before
Cordite was invented.

Beware antique knives and forks. Cellulose nitrate was used as a
substitute for ivory in handles (Trade name Xylonite). Piano keys, too.
Now outlawed in just about every jurisdiction.

Early movies were made on nitrate stock. Now dangerously unstable.
Projection box fires were common, once. Once burning, it's next to
impossible to extinguish. Movie houses burned down.

Solder mask? FR4 wouldn't be FR, if they used cellulose nitrate ;-)
--
"Design is the reverse of analysis"
(R.D. Middlebrook)
Adrian Tuddenham
2014-02-09 16:42:17 UTC
Permalink
Post by Fred Abse
Post by Adrian Tuddenham
The big danger is that cellulose nitrate (nitrocellulose) is potentially
explosive. For many years now, in all applications except record
mastering and some analysis laboratory processes, it has been replaced by
cellulose acetate.
In the 19th, and early 20th centuries, men wore collars made out of the
stuff (Celluloid). Picture the scene; man wearing celluloid collar leans
over gas light jet, to light a cigar. POOF!
Photographers would occasionally use a celluloid collar when they ran out
of flash powder.
AKA guncotton. Evil stuff. Naval guns used it as a propellant, before
Cordite was invented.
Beware antique knives and forks. Cellulose nitrate was used as a
substitute for ivory in handles (Trade name Xylonite). Piano keys, too.
Now outlawed in just about every jurisdiction.
Early movies were made on nitrate stock. Now dangerously unstable.
Projection box fires were common, once. Once burning, it's next to
impossible to extinguish. Movie houses burned down.
Solder mask? FR4 wouldn't be FR, if they used cellulose nitrate ;-)
There were a couple of very telling phrases in a book about it [from
memory]:

1) " There were attempts to use cellulose nitrate as a military
explosive but it was soon replaced by more stable and predictable
compounds such as nitro-glycerine."

2) "Fighting a cellulose nitrate fire is best left to the building's
automatic extinguishing system, if this has survived the initial
explosions intact. In any event, keep personnel as far away as possible
until all the cellulose nitrate has burnt out, then tackle the resulting
conventional fire."


I should add that a smouldering nitrate fire evolves copious quantities
of carbon monoxide, cyanide and hydrogen - until the exothermic reaction
reaches flash point...
--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
Tim Williams
2014-02-09 17:02:11 UTC
Permalink
Post by Fred Abse
In the 19th, and early 20th centuries, men wore collars made out of the
stuff (Celluloid). Picture the scene; man wearing celluloid collar leans
over gas light jet, to light a cigar. POOF!
Photographers would occasionally use a celluloid collar when they ran out
of flash powder.
Never heard that before, but perhaps plausible given the process control
of the day?
Post by Fred Abse
AKA guncotton. Evil stuff. Naval guns used it as a propellant, before
Cordite was invented.
Well, all production hand guns do, too.

I'd hardly call it evil stuff. It burns, yes, but it's no nitroglycerin.

Cordite it would seem has been *long* out of use, with "triple base" types
being preferred now.
http://en.wikipedia.org/wiki/Cordite
The term is British; though largely similar formulations have been in use
since their invention, I don't know that it was ever called Cordite in the
US.
Post by Fred Abse
Beware antique knives and forks. Cellulose nitrate was used as a
substitute for ivory in handles (Trade name Xylonite). Piano keys, too.
Now outlawed in just about every jurisdiction.
Ping-pong balls too, e.g.
http://www.liveleak.com/view?i=b1c_1354489655
Sounds like the guys are German, so I doubt those at least are really
"outlawed in just about every jurisdiction".

Heh... with all the hubbub about plasticizers these days, one can only
imagine what they'd think of that sort of stuff now... Who cares about
plasticizers, my plasticware is giving me a headache! (Organic nitrates
are notoriously strong vasodilators, hence, for example, pounding
headaches after working near (let alone with) nitroglycerin and such.)
Post by Fred Abse
Early movies were made on nitrate stock. Now dangerously unstable.
Projection box fires were common, once. Once burning, it's next to
impossible to extinguish. Movie houses burned down.
The difference is, the gun stuff has a high nitrate content, the ping-pong
ball stuff has low nitrate content. It burns slowly. Probably not slowly
enough to extinguish short of an intense frigid CO2 blast, but it will
just about never explode.

Could be the old production stuff wasn't very well controlled, so the
minimum nitrate content wasn't as low as would really be desired for
safety. I don't know the intricacies of production like that.

Even the stuff they put in guns doesn't explode. Even when mixed with a
rather considerable fraction of nitroglycerin (e.g., Bullseye Smokeless at
up to 40%). Burns *very quickly*, ah, yep...

Offhand I don't know what the drop test of the latter is. It will
detonate at some point... just about every exothermic mixture does, from
the fairly inert but notable TNT, to innocuous thermite blends*. I wonder
how it compares to the others (like TNT, pure high-nitro NC, low-nitro,
and the old fashioned black powder).

*While I'm drifting off topic here, it's amusing how powerful some
thermite mixtures actually are. You can take a torch to some copper wire,
heat it until black, scrape off the oxide, then file some aluminum into
the pile of oxide. Place the mixture on a heavy steel plate, and tap it
with a hammer. But do cover your ears first! Somewhat larger, and better
mixed, compositions are used in 'exploding targets' for target practice.
Note the distinctive color of finely divided copper:

I don't recall that traditional (iron) thermite is ever explosive (well,
when dry.. moisture, that's cheating), but that might simply mean you
aren't trying hard enough.

Tim
--
Seven Transistor Labs
Electrical Engineering Consultation
Website: http://seventransistorlabs.com
Fred Abse
2014-02-09 19:32:03 UTC
Permalink
Post by Tim Williams
The term is British; though largely similar formulations have been in use
since their invention, I don't know that it was ever called Cordite in the
US.
I figured Adrian would more likely have heard of Cordite, than the
DuPont propellants from WWI era. Some Cordite was made in Canada.
Post by Tim Williams
Even the stuff they put in guns doesn't explode. Even when mixed with a
rather considerable fraction of nitroglycerin (e.g., Bullseye Smokeless at
up to 40%). Burns *very quickly*, ah, yep...
Propellants shouldn't explode (detonate). If they did, your pistol slide
would end up sticking out of the back of your neck, and you'd be short
some fingers :-)

Deflagration versus detonation.
Post by Tim Williams
Ping-pong balls too, e.g.
http://www.liveleak.com/view?i=b1c_1354489655 Sounds like the guys are
German, so I doubt those at least are really "outlawed in just about
every
jurisdiction".
It was knife handles, and piano keys to which I was referring.
--
"Design is the reverse of analysis"
(R.D. Middlebrook)
Neon John
2014-02-10 02:25:06 UTC
Permalink
On Sun, 9 Feb 2014 11:02:11 -0600, "Tim Williams"
Post by Tim Williams
Post by Fred Abse
Photographers would occasionally use a celluloid collar when they ran out
of flash powder.
Never heard that before, but perhaps plausible given the process control
of the day?
Definitely will not work. The flash from flash powder comes from the
powdered aluminum absent in celluloid.

Flash consists of aluminum dust and potassium perchlorate. I went
through a period earlier in my life where I was intensely interested
in old photographic techniques, including the use of flash powder. Had
to make my own, of course. Learned why the flashes of old consisted
of a trough to put the flash powder in. Pile it up in a pile and it
transitions to detonation. That is, you end up holding a large M-80
like creature above your head.

Celluloid burns with a quiet almost transparent flame if uncontained.
Its pressure vs reaction rate curve is very steep, however. That's
why it is the only ingredient (in powder form) (plus burn rate
modifiers, of course) in single base smokeless gunpowder. Double base
is a mixture of nitrocellulose and nitroglycerine.

John
John DeArmond
http://www.neon-john.com
http://www.fluxeon.com
Tellico Plains, Occupied TN
See website for email address
DecadentLinuxUserNumeroUno
2014-02-09 20:31:45 UTC
Permalink
Post by Adrian Tuddenham
The big danger is that cellulose nitrate (nitrocellulose) is potentially
explosive.
Potentially?

Try *IS* explosive.
Adrian Tuddenham
2014-02-09 21:19:25 UTC
Permalink
Post by DecadentLinuxUserNumeroUno
Post by Adrian Tuddenham
The big danger is that cellulose nitrate (nitrocellulose) is potentially
explosive.
Potentially?
Try *IS* explosive.
I agree, but it is still used relatively safely in the form of a thin
lacquer film on metal. Master disc recordings are made by cutting the
grooves into nitrate-coated blanks (which are called "Acetates" by the
trade because of the bad reputation the word "nitrate" acquired ). The
swarf from the cutting process is fairly dangerous, but the discs
themselves take a lot of heating up before they begin to catch fire.

The real danger is in old 'direct recordings' which were made on similar
material many years ago. The nitrate begins to undergo a chemical
change which makes it more unstable. The first sign is of shrinkage,
where occasional flashes of the silvery base material can be seen
through splits at the bottom of the groove.

The next stage is 'mud cracking' as the shrinkage becomes worse; at this
stage, some flakes begin to become detached from the underlying material
and no longer have the benefit of the heat sinking effect of the bulk of
the alloy disc. Records in this condition are still playable with a
sapphire or diamond stylus, but should be drenched in water throughout
the process.

The final stage is the formation of reddish-brown powder. This is a
highly unstable contact-sensitive explosive - discs showing this effect
are best left alone until the bomb squad arrives.
--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
h***@gmail.com
2014-02-10 01:51:10 UTC
Permalink
Post by d***@gmail.com
has the glossy finish, is nitrocellulose
lacquer. As far as I know nitrocellulose
lacquer is toxic. If so, what is the
No it's not particularly toxic. I doubt they are using nitro still.

Check out "Bruce Ames Youtube" He was the #1 toxicologist in the US, and the "Ames Test" is named after him.
Now, at age 80, he says the programs scaring us about toxicity are all BS. He says his whole life work was invalid. Toxic substances don't cause cancer. The various toxic scares are all a lie, and mainly an excuse for bureaucratic funding and chance to walk around with a stick up their ass.
Check the U-toob.
josephkk
2014-02-11 06:07:51 UTC
Permalink
Post by h***@gmail.com
Post by d***@gmail.com
has the glossy finish, is nitrocellulose
lacquer. As far as I know nitrocellulose
lacquer is toxic. If so, what is the
No it's not particularly toxic. I doubt they are using nitro still.
Check out "Bruce Ames Youtube" He was the #1 toxicologist in the US, and the "Ames Test" is named after him.
Now, at age 80, he says the programs scaring us about toxicity are all BS. He says his whole life work was invalid. Toxic substances don't cause cancer. The various toxic scares are all a lie, and mainly an excuse for bureaucratic funding and chance to walk around with a stick up their ass.
Check the U-toob.
That turned out to be a rather interesting tip. As in Holy Shit, i have
been missing the boat here.

Thranx

?-)

Continue reading on narkive:
Loading...