Homebrew PCBs

Hi,

A few questions regarding MG Chemical's Liquid Tin product:

1) I just purchased a bottle of Liquid Tin. In the bottom of the (unopened) bottle, there's a lot of white precipitate and a few black things. It doesn't mix in if I shake it. Is this normal or did I receive a defective product?

2) I understand that the tinning process is very stinky and produces toxic gases. Is it ok to use it outside, since my lab (a.k.a. garage) is not well ventilated? Does cold (down to 50 deg or so) or heat (up to 90 deg or so) affect its operation?

3) Can I re-use Liquid Tin by pouring it back into the original bottle? Or should it be discarded after one use?

4) How do I dispose of Liquid Tin in an eco-friendly manner?

5) Any hints on using Liquid Tin to ensure good conductivity and prevent copper corrosion?

Thanks,
Jim

On Jan 30, 2010, at 2:38 AM, jimofc300 wrote:

> 1) I just purchased a bottle of Liquid Tin. In the bottom of the  
> (unopened) bottle, there's a lot of white precipitate and a few  
> black things. It doesn't mix in if I shake it. Is this normal or did  
> I receive a defective product?

Mine’s the same way.  It seems to work ok, but the precipitate looks  
very odd to me.

> 2) I understand that the tinning process is very stinky and produces  
> toxic gases. Is it ok to use it outside, since my lab (a.k.a.  
> garage) is not well ventilated?

It is smelly, but I’ve taken to putting some into a clear plastic  
container (left over from some Chinese food, I believe) and both  
storing some in there and also using it for soaking the board.  I just  
pop the board in and close the lid and watch for it to be done.  I  
don’t smell anything when I do it that way.

> 3) Can I re-use Liquid Tin by pouring it back into the original  
> bottle? Or should it be discarded after one use?

My bottle turned a bit cloudy when I poured used mixture back in, so I  
went the reusable solution method above.

I’m looking forward to seeing answers to questions 4 and 5. :-)

--
Brian Lalor / blalor@...
     Humanity is rife with enterprising idiots whose final words may  
well have
     been "hold my beer and watch this."

On Sat, 30 Jan 2010 07:38:30 -0000, you wrote:

>Hi,
>
>A few questions regarding MG Chemical's Liquid Tin product:
>
>1) I just purchased a bottle of Liquid Tin. In the bottom of the (unopened) bottle, there's a lot of white precipitate and a few black things. It doesn't mix in if I shake it. Is this normal or did I receive a defective product?

Mine is like that, too.  Works fine.
>
>2) I understand that the tinning process is very stinky and produces toxic gases. Is it ok to use it outside, since my lab (a.k.a. garage) is not well ventilated? Does cold (down to 50 deg or so) or heat (up to 90 deg or so) affect its operation?
>

And the chemicals are nasty, so use gloves, avoid fumes, etc.

Temperature does have an effect on all chemical reactions, but the 90
degrees is not a problem, although you might be happier at 60 degrees.

>3) Can I re-use Liquid Tin by pouring it back into the original bottle? Or should it be discarded after one use?

At that price, it goes back into the bottle.   It can be used again
and again.
>
>4) How do I dispose of Liquid Tin in an eco-friendly manner?
>
Not sure, hazardous waste collection seems to come to mind.


>5) Any hints on using Liquid Tin to ensure good conductivity and prevent copper corrosion?

3 to 5 minutes as they mention.  Make sure the boards are clean, a
brief scour with a scotchbrite pad is good.  If you have an area that
doesn't plate, then pulsar recommends a bit of buffing with whatever,
and re-immersion in the bath.

Note that this is a tin plate, not a tin/lead, so solder coating some
of the SMT pins (especially fine pitch) is a good idea.

There's a tutorial on SMD soldering at www.avrfreaks.net that has a
lot of useful tips.  Generally a flux pen is good, and I've found that
sweat soldering to the pre tinned (with solder) pads works well for
TQFP packages.

Harvey

>
>Thanks,
>Jim
>
>
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

"jimofc300" <jim@...> writes:

> 1) I just purchased a bottle of Liquid Tin. In the bottom of the
> (unopened) bottle, there's a lot of white precipitate and a few
> black things. It doesn't mix in if I shake it. Is this normal or did
> I receive a defective product?

It's more of the tin salts, to keep the solution saturated.
Eventually that stuff dissolves as you use up the tin and it needs
more.

> 3) Can I re-use Liquid Tin by pouring it back into the original
> bottle? Or should it be discarded after one use?

Definitely re-use it!

> 5) Any hints on using Liquid Tin to ensure good conductivity and
> prevent copper corrosion?

Soak at least five minutes, flipping the board over occasionally and
agitating it for an even coat.  Rince with COLD water as soon as it
comes out, and gently wipe with a paper towel to dry the tin before it
has a chance to start corroding from the water.  Cold dry tin gives a
very pretty surface.

A thin tinning seems to be affected by flux, though, exposing the
copper below.

Years back in the September 1971 issue of "Ham Radio Magazine" Larry Hutchinson had an article "Practical Photofabrication of Printed-circuit boards".  In that article he had an electroless tin-plating bath that worked quite well, did lots of boards with it.

 To 100ml distilled water add  500 milligrams Stannous Chloride, 2 grams Thiourea, and 3 grams of Sulfamic acid.  The chemicals are all powders so they keep but the bath is unstable, so only mix enough for one days job. All you need is enough to cover the board.  Action takes 10 to 20 minutes.  The article suggests a few mg of Alizarin or Alizarin Red S can be added as a brightner.  The Alizarin is very expensive and I could not see much difference in the brightness, I abandon the Alizarin when I ran out. Don't remember any odors, but with all chemicals you should take proper care and dispose properely.

Craig

Jim,
I would not return the used solution to the bottle.  I would think the Cu ions from the board as the Tin plates on would degrade the stock solution. Best thing would be to just use as little as possible and dispose of it after use. 

--- In Homebrew_PCBs@yahoogroups.com, "jimofc300" <jim@...> wrote:

>
> Hi,
> 
> A few questions regarding MG Chemical's Liquid Tin product:
> 
> 1) I just purchased a bottle of Liquid Tin. In the bottom of the (unopened) bottle, there's a lot of white precipitate and a few black things. It doesn't mix in if I shake it. Is this normal or did I receive a defective product?
> 
> 2) I understand that the tinning process is very stinky and produces toxic gases. Is it ok to use it outside, since my lab (a.k.a. garage) is not well ventilated? Does cold (down to 50 deg or so) or heat (up to 90 deg or so) affect its operation?
> 
> 3) Can I re-use Liquid Tin by pouring it back into the original bottle? Or should it be discarded after one use?
> 
> 4) How do I dispose of Liquid Tin in an eco-friendly manner?
> 
> 5) Any hints on using Liquid Tin to ensure good conductivity and prevent copper corrosion?
> 
> Thanks,
> Jim
>

> Best thing would be to just use as little as possible and dispose of
> it after use. 

Just read both manual and MSDS
http://www.mgchemicals.com/downloads/pdf/specsheets/421.pdf
http://www.mgchemicals.com/msds/english/liquid/421-liquid.pdf
http://www.mgchemicals.com/products/421.html 

It says:
Clean the board, either by acid dip, degrease or both
5 minutes on that thing
HOT water rinse

It's a fluoroboric mix, which is a strong acid, in it the tin doesn't
oxidize much in air, it can be left in the tray, and still works for
long. That's why is a good product that worth the money. Besides the
'boric' name it's not more harmful than other strong acid. Disposal
shouldn't make such doubts in a so long lasting product. The white
deposit should be stannous fluoroborate and not oxidized tin like other
inferior mixes, someone said it get plated with use. The thing is smelly
thanks to thiourea, the name says it all, and it's a suspected
carcinogen. Use gloves and don't share bottles/trays for it's use with
other household things. There is no harmful gases produced, other than
smell a chemical is always bad. But every immersion tin on copper mixes
with msds found by google uses thiourea, so no other option for that.

This isn't a electroless chemistry, is a immersion chemistry. Works by
the surface transactions between copper and tin on the acid, in
equilibrium. Thiourea produces a strong complex with copper, so forces
the reaction to one side. Will go until surface cover with tin. Any
oxide or grease on surface voids the reaction. A good clean surface
makes a instantaneous beautiful finish, not a gray dark or black finish
slowly made. Thiourea makes a fatty thing with copper left on the tin
surface so it should be used warm-hot water to clean pcb after use. If
used corrosive liquids on the so thin tin surface, like some flux, the
tin is like washed away.

Questions ask mgchemicals.

Simao Cardoso <simaocardoso@...> writes:
> HOT water rinse

Huh.  Cold seems to work just fine, though, but forgetting to rinse
results in a horrible mess.  I'll have to re-read the directions on
the bottle.

Then again, MG said their UV film wouldn't develop in sodium carbonate
but that works just fine too.

I have been using the same bottle for about 2 years now (give or take a bit).  I pour it into an old film developing tray, toss my PCB into it for a couple of minutes, then return the stuff to its original bottle.  It certainly has NOT degraded the product's ability to tin a circuit board.  As for rinsing, I put it in the sink, and run water on it for about 10 to 20 seconds - cold or warm water, whatever comes out of the faucet.

Yes, the stuff stinks a tiny bit like rotten eggs.  Not knowing what this chemical actually is, I usually do it outdoors to be safe.

Chris

On Mon, 1 Feb 2010, Chris wrote:

> I have been using the same bottle for about 2 years now (give or take a 
> bit).  I pour it into an old film developing tray, toss my PCB into it 
> for a couple of minutes, then return the stuff to its original bottle. 
> It certainly has NOT degraded the product's ability to tin a circuit 
> board.  As for rinsing, I put it in the sink, and run water on it for 
> about 10 to 20 seconds - cold or warm water, whatever comes out of the 
> faucet.
>
> Yes, the stuff stinks a tiny bit like rotten eggs.  Not knowing what 
> this chemical actually is, I usually do it outdoors to be safe.

That might be the thiourea giving off hydrogen sulfide.  If you think you 
can tough out that smell, you're intoxicated with it.

-- 
David Griffith
dgriffi@...

A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

In article <hk6gsf+3f0c@...>,
   Chris <lcdpublishing@...> wrote:
> Yes, the stuff stinks a tiny bit like rotten eggs.  Not knowing what
> this chemical actually is, I usually do it outdoors to be safe.

It's the Thiourea, which, incidentally, is reputed to be carcinogenic.

-- 
Stuart
http://www.torrens.org.uk/ZFC/gallery/winsor.html

Folks, ya'll have talked so much about the great finish given by this tin stuff, I just might have to order a bottle - Any suggestions of a place to order from Alabama, USA? 

Cost for what size bottle? Typical cost per board spread over life of bottle?

Thanks for any info,

Ken H>

--- In Homebrew_PCBs@yahoogroups.com, DJ Delorie <dj@...> wrote:

>
> 
> Simao Cardoso <simaocardoso@...> writes:
> > HOT water rinse
> 
> Huh.  Cold seems to work just fine, though, but forgetting to rinse
> results in a horrible mess.  I'll have to re-read the directions on
> the bottle.
> 
> Then again, MG said their UV film wouldn't develop in sodium carbonate
> but that works just fine too.
>

On Mon, 01 Feb 2010 18:21:22 -0000, "sailingto" <sailingtoo@...>
wrote:

> Folks, ya'll have talked so much about the great finish given by this tin
> stuff, I just might have to order a bottle - Any suggestions of a place
to
> order from Alabama, USA? 
> 
> Cost for what size bottle? Typical cost per board spread over life of
> bottle?

I bought a bottle from Mouser for about $30, for 8oz, I think.  Quite
pricey.  I expect it to last a good, long time, however.  I've got about 1"
of the solution in a small plastic container that I'm dipping the boards
into.  I have no idea if the solution itself will wear out, or if the
volume will just reduce as I dip my boards and (gloved) fingers into it. 
If it doesn't wear out, imagine how long that much water will last if you
dunk your board in there repeatedly.  :-)

-- 
Brian Lalor
blalor@...

Well the tin isn't coming from nothing, so it must definitely wear out
eventually.

ST

On Mon, Feb 1, 2010 at 7:36 PM, Brian Lalor <blalor@...> wrote:
>
>
> I bought a bottle from Mouser for about $30, for 8oz, I think.  Quite
> pricey.  I expect it to last a good, long time, however.  I've got about 1"
> of the solution in a small plastic container that I'm dipping the boards
> into.  I have no idea if the solution itself will wear out, or if the
> volume will just reduce as I dip my boards and (gloved) fingers into it.
> If it doesn't wear out, imagine how long that much water will last if you
> dunk your board in there repeatedly.  :-)
>
> --
> Brian Lalor
> blalor@...
>

On Mon, 01 Feb 2010 18:21:22 -0000, you wrote:

>Folks, ya'll have talked so much about the great finish given by this tin stuff, I just might have to order a bottle - Any suggestions of a place to order from Alabama, USA? 

If you're in the Birmingham area, Forbes used to have it, as well as
some other MG chemicals.  No idea if they still do.

Check Mouser or Digikey amongst others.  
>
>Cost for what size bottle? Typical cost per board spread over life of bottle?
>

About 15 dollars for 100 ml, and about 30 for 500, or thereabouts.  I
got the larger one.  Works for me.  Number of boards depends on plated
copper size, of course, but I normally do about a 4 * 6 board, double
sided.  I'd say roughly at least 50 such boards, but MG chemicals has
the exact data.

Harvey

>Thanks for any info,
>
>Ken H>
>
>--- In Homebrew_PCBs@yahoogroups.com, DJ Delorie <dj@...> wrote:
>>
>> 
>> Simao Cardoso <simaocardoso@...> writes:
>> > HOT water rinse
>> 
>> Huh.  Cold seems to work just fine, though, but forgetting to rinse
>> results in a horrible mess.  I'll have to re-read the directions on
>> the bottle.
>> 
>> Then again, MG said their UV film wouldn't develop in sodium carbonate
>> but that works just fine too.
>>
>
>
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

DJ Delorie wrote:

> 
> Huh. Cold seems to work just fine, though, but forgetting to rinse
> results in a horrible mess. I'll have to re-read the directions on
> the bottle.

If cold water works, great. I have washed fat dirty dishes with cold
water some times already. 

And to who says it's expensive. This side of the Atlantic bungard sells
an unmixed kit that only lasts 1 month after mixed, for 25eur!. And if
keep the bottle full to avoid air and away from light, like inside a
whisky bottle can. But thats bungard if they didn't sell crap, the
market was already satisfied. And mgchemicals bottle is transparent, and
the liquid can be left on the tray and still works, so don't complain. 

> 
> Then again, MG said their UV film wouldn't develop in sodium carbonate
> but that works just fine too.

There is a messenger to blame for that (me)! I said riston manual also
have sodium carbonate instructions and according to msds the composition
have similarities. But if you are using NaHCO3 easier to get, it may be
becoming Na2CO3 in half concentration. So if your developing times
increased (dry film not code hopefully :>), it can explain the problems
you reported with dry film. And you should follow the manual and get
some potassium carbonate from ebay for cheap.

--- In Homebrew_PCBs@yahoogroups.com, David Griffith <dgriffi@...> wrote:
>
> On Mon, 1 Feb 2010, Chris wrote:
> 
> > I have been using the same bottle for about 2 years now (give or take a 
> > bit).  I pour it into an old film developing tray, toss my PCB into it 
> > for a couple of minutes, then return the stuff to its original bottle. 
> > It certainly has NOT degraded the product's ability to tin a circuit 
> > board.  As for rinsing, I put it in the sink, and run water on it for 
> > about 10 to 20 seconds - cold or warm water, whatever comes out of the 
> > faucet.
> >
> > Yes, the stuff stinks a tiny bit like rotten eggs.  Not knowing what 
> > this chemical actually is, I usually do it outdoors to be safe.
> 
> That might be the thiourea giving off hydrogen sulfide.  If you think you 
> can tough out that smell, you're intoxicated with it.

Yes, Hydrogen Sulfide will dull the sense of smell, possibly allowing the
person breathing it to receive a fatal dose.  Use caution!

I used to have a really nice Tin plating recipe.  It used Sodium Chloride,
Stannous Chloride, and Sodium Cyanide.  Yes, I'm being serious, and 
no, I don't use it any more.

> -- 
> David Griffith
> dgriffi@...

Dave

On Tue, 2 Feb 2010, Dave wrote:

> Yes, Hydrogen Sulfide will dull the sense of smell, possibly allowing the
> person breathing it to receive a fatal dose.  Use caution!
>
> I used to have a really nice Tin plating recipe.  It used Sodium Chloride,
> Stannous Chloride, and Sodium Cyanide.  Yes, I'm being serious, and
> no, I don't use it any more.

What's its shelf-life in solution?

-- 
David Griffith
dgriffi@...

A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

--- In Homebrew_PCBs@yahoogroups.com, David Griffith <dgriffi@...> wrote:
>
> On Tue, 2 Feb 2010, Dave wrote:
> 
> > Yes, Hydrogen Sulfide will dull the sense of smell, possibly allowing the
> > person breathing it to receive a fatal dose.  Use caution!
> >
> > I used to have a really nice Tin plating recipe.  It used Sodium Chloride,
> > Stannous Chloride, and Sodium Cyanide.  Yes, I'm being serious, and
> > no, I don't use it any more.
> 
> What's its shelf-life in solution?

If it wasn't exposed to air, it would last many months.  If exposed to air
(as in some fool left it out in the plating tray overnight), then it would die 
within a few hours.  

> -- 
> David Griffith
> dgriffi@...

Dave

Hi,
has anyone ever heard of this "Liquid Tin" by m.g. chemicals ?
this material is supposed to plate the PCB after the etch process, and passivate the copper. 
I never seen this stuff sold anywhere, and I can't get it since I live in Israel. 

first, a link to see it with your own eyes:
http://www.youtube.com/watch?v=3aEwTRMEkOM
look at around 3:30 minutes...

second, does anyone know how to home-brew this material ? Is it dangerous to use ?

third, does any of you use any other process to passivate the copper after etching ?

Thanks in advance, 
Liquias.

Hi,

Check this link   http://il.farnell.com/cif/bs200/tinning-salt/dp/4148071   

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of liquias
Sent: 26 November 2010 09:44
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Liquid Tin

 

  

Hi,
has anyone ever heard of this "Liquid Tin" by m.g. chemicals ?
this material is supposed to plate the PCB after the etch process, and
passivate the copper. 
I never seen this stuff sold anywhere, and I can't get it since I live in
Israel. 

first, a link to see it with your own eyes:
http://www.youtube.com/watch?v=3aEwTRMEkOM
look at around 3:30 minutes...

second, does anyone know how to home-brew this material ? Is it dangerous to
use ?

third, does any of you use any other process to passivate the copper after
etching ?

Thanks in advance, 
Liquias.



  _____  

No virus found in this message.
Checked by AVG - www.avg.com
Version: 10.0.1170 / Virus Database: 426/3280 - Release Date: 11/25/10



[Non-text portions of this message have been removed]

On 26/11/2010 09:43, liquias wrote:
> Hi,
> has anyone ever heard of this "Liquid Tin" by m.g. chemicals ?
> this material is supposed to plate the PCB after the etch process, and passivate the copper.
> I never seen this stuff sold anywhere, and I can't get it since I live in Israel.
>
> first, a link to see it with your own eyes:
> http://www.youtube.com/watch?v=3aEwTRMEkOM
> look at around 3:30 minutes...
>
> second, does anyone know how to home-brew this material ? Is it dangerous to use ?
>
> third, does any of you use any other process to passivate the copper after etching ?


I've got a bottle of the tin plating compound on this web page:

http://www.megauk.com/pcb_chemicals.php

but haven't tried it.

Leon
-- 
Leon Heller
G1HSM

I have used it quite recently actually, and it happens to work quite
excellently.

On Fri, Nov 26, 2010 at 3:38 AM, Leon Heller <leon355@...m> wrote:

>
>
> On 26/11/2010 09:43, liquias wrote:
> > Hi,
> > has anyone ever heard of this "Liquid Tin" by m.g. chemicals ?
> > this material is supposed to plate the PCB after the etch process, and
> passivate the copper.
> > I never seen this stuff sold anywhere, and I can't get it since I live in
> Israel.
> >
> > first, a link to see it with your own eyes:
> > http://www.youtube.com/watch?v=3aEwTRMEkOM
> > look at around 3:30 minutes...
> >
> > second, does anyone know how to home-brew this material ? Is it dangerous
> to use ?
> >
> > third, does any of you use any other process to passivate the copper
> after etching ?
>
> I've got a bottle of the tin plating compound on this web page:
>
> http://www.megauk.com/pcb_chemicals.php
>
> but haven't tried it.
>
> Leon
> --
> Leon Heller
> G1HSM
>  
>


[Non-text portions of this message have been removed]

Krzysztof Juszczak wrote:

> 
> Check this link
> http://il.farnell.com/cif/bs200/tinning-salt/dp/4148071 
> 

That's NOT an imersion tin plating for copper, it's the salt used in the
outdated and stupid roll tinning machines. It's used on top of melted
solder on the back of the lower roll, for proper distribution of tin
across the stainless steel roll.

> From: Homebrew_PCBs@yahoogroups.com
> [mailto:Homebrew_PCBs@yahoogroups.com]
> On Behalf Of liquias
> Sent: 26 November 2010 09:44
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] Liquid Tin
> 
> Hi,
> has anyone ever heard of this "Liquid Tin" by m.g. chemicals ?
> this material is supposed to plate the PCB after the etch process, and
> passivate the copper. 
> I never seen this stuff sold anywhere, and I can't get it since I live
> in
> Israel. 
> 
> first, a link to see it with your own eyes:
> http://www.youtube.com/watch?v=3aEwTRMEkOM
> look at around 3:30 minutes...
> 
> second, does anyone know how to home-brew this material ? Is it
> dangerous to
> use ?
> 
> third, does any of you use any other process to passivate the copper
> after
> etching ?
> 
> Thanks in advance, 
> Liquias.
> 
> _____ 
> 
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1170 / Virus Database: 426/3280 - Release Date: 11/25/10
> 
> [Non-text portions of this message have been removed]
> 
> 
> 
> 
>

Yes, it is dangerous and it could be home brewed- YMMV

MG Chemicals MSDS shows it is stannus sulfate, sulfuric acid, and as I
recall, it is mixed with water for the balance.

CAS# Chemical Name Percentage by weight ACGIH TWA Osha Pel Osha Stel
7488-55-3 Stannous Sulfate 1-3 % N/E N/E N/E
7664-93-9 Sulfuric acid 9-10 % 0.2 mg/m3 N/E N/E

I would recommend getting it from a known source pre-mixed for the intended
purpose.

73
Bill Laakkonen
N4BKT

On Fri, Nov 26, 2010 at 4:43 AM, liquias <liquias@...> wrote:

>
>
> Hi,
> has anyone ever heard of this "Liquid Tin" by m.g. chemicals ?
> this material is supposed to plate the PCB after the etch process, and
> passivate the copper.
> I never seen this stuff sold anywhere, and I can't get it since I live in
> Israel.
>
> first, a link to see it with your own eyes:
> http://www.youtube.com/watch?v=3aEwTRMEkOM
> look at around 3:30 minutes...
>
> second, does anyone know how to home-brew this material ? Is it dangerous
> to use ?
>
> third, does any of you use any other process to passivate the copper after
> etching ?
>
> Thanks in advance,
> Liquias.
>
>  
>


[Non-text portions of this message have been removed]

Hi,

this is my first post, so I hope you don't mind if I just stick my nose 
right into this thread. It's just I've found it very interesting.

Actually, Bill is totally right. Liquid tin can be perfectly homebrewed, 
but it's quite dangerous for anybody lacking good skills in chemistry. 
If I understood well, the MSDS sheet for MG Chemicals Liquid Tin is this 
one: http://www.mgchemicals.com/msds/english/421-liquid.pdf

and it lists the following hazardous chemicals:

CAS# Chemical Name Percentage by weight ACGIH TWA Osha Pel Osha Stel
16872-11-0 Fluoroboric Acid 9-11% 2.5mg/m3 2.5mg/m3 N/E
13814-97-6 Stannous Fluoroborate 9-11% 2mg/m3 2mg/m3 N/E
62-56-6 Thiourea 4-6% 2.5mg/m3 N/E N/E

To start with, fluoroboric acid is dangerous enough by itself, but safe 
enough if handled carefully. However, it's probably not very easy to get 
hold of the technical grade stuff. Preparing it is pretty 
straightforward, but one of the reagents needed is hydrofluoric acid. 
Hydrofluoric acid is *very* toxic and not something to be messing around 
with. With access to a good fume hood and appropriate labware (or just 
take the risk of working with hydrofluoric acid in an open, 
well-ventilated place), then fluoroboric acid can be prepared rather easily.

A way of doing electroless tinning has been already posted in this 
group, I copy the formula down here for the sake of simplicity:

.5g Stannous Chloride
  2.0g Thiourea
3.0g Sulfamic Acid
100.0 mL Distilled water

These chemicals are much easier to get from your local supplier and can 
be handled safely without any special precautions.

I hope this helps!

Pablo

Am 26.11.2010 15:47, schrieb William Laakkonen:

> Yes, it is dangerous and it could be home brewed- YMMV
>
> MG Chemicals MSDS shows it is stannus sulfate, sulfuric acid, and as I
> recall, it is mixed with water for the balance.
>
> CAS# Chemical Name Percentage by weight ACGIH TWA Osha Pel Osha Stel
> 7488-55-3 Stannous Sulfate 1-3 % N/E N/E N/E
> 7664-93-9 Sulfuric acid 9-10 % 0.2 mg/m3 N/E N/E
>
> I would recommend getting it from a known source pre-mixed for the intended
> purpose.
>
> 73
> Bill Laakkonen
> N4BKT
>
> On Fri, Nov 26, 2010 at 4:43 AM, liquias<liquias@...>  wrote:
>
>>
>> Hi,
>> has anyone ever heard of this "Liquid Tin" by m.g. chemicals ?
>> this material is supposed to plate the PCB after the etch process, and
>> passivate the copper.
>> I never seen this stuff sold anywhere, and I can't get it since I live in
>> Israel.
>>
>> first, a link to see it with your own eyes:
>> http://www.youtube.com/watch?v=3aEwTRMEkOM
>> look at around 3:30 minutes...
>>
>> second, does anyone know how to home-brew this material ? Is it dangerous
>> to use ?
>>
>> third, does any of you use any other process to passivate the copper after
>> etching ?
>>
>> Thanks in advance,
>> Liquias.
>>
>>
>>
>
> [Non-text portions of this message have been removed]
>
>
>
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http://www.delorie.com/pcb/liquidtin/