I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Thanks

Forgot to mention; Another store nearby stocks 60/40 tin/lead rosin
core (says acid core) and the same kind but its made without the rosin
flux. So many to choose from; they are all around $12.00 a small spool.

wrote in message
ups.com...
I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Thanks


Unless you are working with circuits that have known lead-free solder on it,
go with the 63/37 rosin core. Usually it is more common to find a 60/40
rosin core, but either is fine with a slight preference to the 63/37. If
you look at a chart for the melting and cooling of the solder, you will see
that the 63/37 does not go into what is called a plastic state as it cools.
What that is , as the solder cools and if the joint is moved, the solder
will have a frosted look and will not make a very good joint. It will not
be shinny as it should look.

Never use the acid core for electronic work. The acid left behind will
absorb water from the air and eat away at the circuits. The acid flux is
mainly used for copper water pipes.

wrote in message
ups.com...
I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Thanks


Lead free solder is specially formulated to fail after not more than 1 year
because the landfill sites aren't filling up with scrap electronic equipment
fast enough!!!

"ian field" wrote in message
...

wrote in message
ups.com...
I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Thanks


Lead free solder is specially formulated to fail after not more than 1
year because the landfill sites aren't filling up with scrap electronic
equipment fast enough!!!

As long as that ?? Panasonic and Sony must have got their formulations
wrong. Theirs fail after 6 weeks ...

When looking at how good ( ! ) lead free solder is, you might ask yourself
why the US military refuse to go near the stuff, and the avionics and
medical instrument industries are exempt from the new rules concerning the
hateful stuff, which are now spreading around the world ...

Arfa

wrote in message
ups.com...
I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Thanks


Phillip -

NEVER use acid core solder on electronic circuits (or kiss that appliance /
project goodbye).

63 / 37 is the Eutectic of Tin and Lead metals.
Eutectic is an English word that comes from the Greek 'eutektos', meaning
'easily melted.'

The lowest temperature at which a mix of two materials will melt.
Often the temperature is an anomaly, that is, it is much lower than the
melting temperatures of only slightly different mixtures. Lead-tin solder is
an example. Lead melts at 327 C, tin at 231 C.
The lowest melting combination is 67 lead, 33 tin ( 180 C ).

Non-eutectic mixtures have a melting or softening (plastic) range. Such
mixtures do not flow well until thoroughly heated past the softening
(plastic) range. Kester solder Alloy temperature chart
http://www.kester.com/en-us/technical/alloy.aspx

g. beat

wrote:

I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

If you have the choice use tin-lead every day !

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Do you need to ?

Most of the alcohols work fine for this. Isopropyl alcohol ( aka isopropanol )
is probably best and easy to obtain.

Graham

wrote:

Forgot to mention; Another store nearby stocks 60/40 tin/lead rosin
core (says acid core) and the same kind but its made without the rosin
flux. So many to choose from; they are all around $12.00 a small spool.

*NEVER* use acid core for electronics.

Graham

Arfa Daily wrote:

"ian field" wrote in message
...

wrote in message
ups.com...
I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Thanks


Lead free solder is specially formulated to fail after not more than 1
year because the landfill sites aren't filling up with scrap electronic
equipment fast enough!!!

As long as that ?? Panasonic and Sony must have got their formulations
wrong. Theirs fail after 6 weeks ...

When looking at how good ( ! ) lead free solder is, you might ask yourself
why the US military refuse to go near the stuff, and the avionics and
medical instrument industries are exempt from the new rules concerning the
hateful stuff, which are now spreading around the world ...

An exemption has also been applied for regarding pro-audio.

Graham

wrote:
I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Thanks



Look for the tin/lead stuff, I've used lead free and hate it.

Pooh Bear spake thus:

wrote:

Forgot to mention; Another store nearby stocks 60/40 tin/lead rosin
core (says acid core) and the same kind but its made without the rosin
flux. So many to choose from; they are all around $12.00 a small spool.

*NEVER* use acid core for electronics.

Amen to that.


--
Any system of knowledge that is capable of listing films in order
of use of the word "****" is incapable of writing a good summary
and analysis of the Philippine-American War. And vice-versa.
This is an inviolable rule.

- Matthew White, referring to Wikipedia on his WikiWatch site
(http://users.erols.com/mwhite28/wikiwoo.htm)

"g. beat " @spam protected wrote in message . ..
wrote in message
ups.com...
I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Thanks


Phillip -

NEVER use acid core solder on electronic circuits (or kiss that appliance /
project goodbye).

63 / 37 is the Eutectic of Tin and Lead metals.
Eutectic is an English word that comes from the Greek 'eutektos', meaning
'easily melted.'

The lowest temperature at which a mix of two materials will melt.
Often the temperature is an anomaly, that is, it is much lower than the
melting temperatures of only slightly different mixtures. Lead-tin solder is
an example. Lead melts at 327 C, tin at 231 C.
The lowest melting combination is 67 lead, 33 tin ( 180 C ).

Non-eutectic mixtures have a melting or softening (plastic) range. Such
mixtures do not flow well until thoroughly heated past the softening
(plastic) range. Kester solder Alloy temperature chart
http://www.kester.com/en-us/technical/alloy.aspx

g. beat


I'm a bit confused about the talk of not using acid fluxed solders in electronics. Just about all conventional solder wires formulated for electronic work, contain one or more cores of rosin based flux. As far as I am aware, this is a fundamentally acidic material when in its activated state, and in fact its being acidic is how it removes the tarnish and oxidation on the surfaces to be joined.

Recent research that I have done regarding the use of lead free solder wire for repair and rework purposes, suggests that because of the inferior wetting properties of lead free, the fluxes employed are actually more aggressive than those in leaded solder, by virtue of being *more acidic*. This is cited as being a reason that lead free soldering is considered to be potentially more injurious to health than leaded soldering, and that workshops should take steps to improve fume extraction.

I obtained this information on very good authority, directly from a recognised specialist, working for a company whose job it is to recommend on such matters. Comments please ??

Arfa

Arfa Daily wrote:

Comments please ??


Certainly.Please turn off the html ! It's counter to accepted Usenet pactice
and makes replies difficult to quote accurately.

Graham

"Pooh Bear" wrote in message
...


Arfa Daily wrote:

Comments please ??


Certainly.Please turn off the html ! It's counter to accepted Usenet
pactice
and makes replies difficult to quote accurately.

Graham


Sorry, don't know how that got switched on. It's set for " plain text "
again now, as it usually always is ...

So, aside from the formatting gripes, any comments on what I was really
asking :- ) ? It's a serious question that I'm interested in answers to.
There must be some posters who better understand the chemistry of soldering
and flux than I do.

Arfa

Arfa Daily wrote:

"Pooh Bear" wrote in message
...


Arfa Daily wrote:

Comments please ??


Certainly.Please turn off the html ! It's counter to accepted Usenet
pactice
and makes replies difficult to quote accurately.

Graham

Sorry, don't know how that got switched on. It's set for " plain text "
again now, as it usually always is ...

So, aside from the formatting gripes, any comments on what I was really
asking :- ) ? It's a serious question that I'm interested in answers to.
There must be some posters who better understand the chemistry of soldering
and flux than I do.

IIRC you were commenting on acid fluxes. The difference is that organic acid
fluxes ( like rosin ) are essentially inactive at average 'room' temperatures
AIUI, so present no long term risk.

Graham

"Arfa Daily" wrote in message
...

"Pooh Bear" wrote in message
...


Arfa Daily wrote:

Comments please ??


Certainly.Please turn off the html ! It's counter to accepted Usenet
pactice
and makes replies difficult to quote accurately.

Graham


Sorry, don't know how that got switched on. It's set for " plain text "
again now, as it usually always is ...

So, aside from the formatting gripes, any comments on what I was really
asking :- ) ? It's a serious question that I'm interested in answers to.
There must be some posters who better understand the chemistry of
soldering
and flux than I do.


You don't really have to understand it, just use rosin for electronic work.
It is almost nonreactive with the components when not heated. The acid
flux will absorb water from the air and eat the circuits.

"Arfa Daily" wrote in
:


Sorry, don't know how that got switched on. It's set for " plain text
" again now, as it usually always is ...

So, aside from the formatting gripes, any comments on what I was
really asking :- ) ? It's a serious question that I'm interested in
answers to. There must be some posters who better understand the
chemistry of soldering and flux than I do.

It's all a matter of words.

Here's the deal. For decades there have been two classes of flux used
for soldering.

1. Acid. This contains strong chemicals to aggressively clean the metals
and is used only for plumbing and similar soldering. It must be cleaned
from the joint after soldering, or corrosion will occur. It has NEVER
been used for electronic work because of this corrosion.

2. Rosin. This is the only flux used for electronic work. It contains
such mild chemicals that it doesn't need to be cleaned after soldering.

Your worry is about "acidity", which is probably nothing to worry about,
as long as you stick to rosin flux and never, ever, use "acid flux."

"Jim Land" wrote in message
. 3.44...
"Arfa Daily" wrote in
:


Sorry, don't know how that got switched on. It's set for " plain text
" again now, as it usually always is ...

So, aside from the formatting gripes, any comments on what I was
really asking :- ) ? It's a serious question that I'm interested in
answers to. There must be some posters who better understand the
chemistry of soldering and flux than I do.

It's all a matter of words.

Here's the deal. For decades there have been two classes of flux used
for soldering.

1. Acid. This contains strong chemicals to aggressively clean the metals
and is used only for plumbing and similar soldering. It must be cleaned
from the joint after soldering, or corrosion will occur. It has NEVER
been used for electronic work because of this corrosion.

2. Rosin. This is the only flux used for electronic work. It contains
such mild chemicals that it doesn't need to be cleaned after soldering.

Your worry is about "acidity", which is probably nothing to worry about,
as long as you stick to rosin flux and never, ever, use "acid flux."

OK, thanks for the answers. I don't have any " worries " about fluxes. It
was just curiosity as I have never seen anyone making the distinction before
with regard to electronic soldering. I have been soldering virtually every
day of my life for 40 odd years, and have always used 'standard' rosin flux
cored solder, which was the only variety I had ever seen offered for normal
electronic work. I had always understood the material rosin, to be mildly
acidic, at least in its activated form, and that this was the basis of its
deoxidising properties. This was the only reason that I was interested in
comments about " never use acid flux " ( I was not the OP having soldering
problems, incidentally ).

So it would seem that the point is academic anyway, as such fluxes are not
offered for electronic work, and anyone dumb enough to try to use plumber's
flux would deserve all they got ...

Just as a matter of interest, I always remove rosin flux residues from
boards, using a proprietory flux remover from Electrolube. IMHO, post
soldering residues left on boards make the job look scrappy and
unprofessional. A couple of years back, I took over the repair of some
commercial boards from another company, who never cleaned up their work.
Interestingly, when I now see boards in for repair, that they did a couple
of years back, the joints and print area around where they've left flux
residues, often look slightly corroded. The air around them in their normal
working environment, is likely to be slightly moist, and the components that
have been replaced, run hot in normal use, so I wonder if this is slightly
reactivating the flux residues ?

Arfa

Good thing I found this group and asked before I bought anything, the
guy at the store counter told me acid core is mainly used for
electronic work and at the other store, the salesperson said to use
rosin core. Thats what confused me; I bought the 63/37 tin/ lead rosin
yesterday and the soldering work turned out OK. Thanks for the help!
Phillip

"Arfa Daily" hath wroth:

Just as a matter of interest, I always remove rosin flux residues from
boards, using a proprietory flux remover from Electrolube. IMHO, post
soldering residues left on boards make the job look scrappy and
unprofessional.

http://en.wikipedia.org/wiki/Soldering
http://www.finishing.com/Library/flux.html
http://www.worldwideflood.com/ark/pitch/pitch.htm

Ignoring acid flux, the rosin fluxes come in two flavors. Water based
and those that require some solvent to remove. Water based fluxes can
allegedly be left on the board and will not eat the copper traces. The
inspiration for this was not to reduce cleanup costs, but because of
environmental and workplace regulations which proscribed the use of
chlorinated hydrocarbon solvents for board cleaning.

The problem is that water soluble fluxes require rather hot water to
remove properly. They're mostly used wave solder machines and not
hand soldering. However, we were using them on the production in
rework stations and of course, I ended up with a few rolls of the
stuff. That's when I discovered that if you leave the flux on the
board for more than a few days, it turns rock hard and no amount of
hot water will get rid of it. The residue is water soluable, but the
big lumps left in rework are not. I experimented with some household
cleaners and found the ammonia cleaner sorta works. It's often easier
to scrape the ossified flux off the board than to wash it as it's
quite brittle.

Another fun experiment was to make my own flux. I managed to
accidentally purchase a roll of solid core 63/37. No flux inside. I
could purchase a tub of Kester rosin solder paste, but that's too easy
and no fun. Rosin is just tree sap and I live in a forest with pine
trees and lots of sticky gooey sap. I just walk outside, scrape off
some pine sap, and I have instant rosin. I melted a big lump of the
stuff to clean it and boil off the volatiles, and voila, instant
sticky rosin flux.

When testing it, I found that the soldering iron was insufficient to
set the flux on fire, but did an adquate job of converting it into
noxious fumes. Rosin works by vaporizing into a cloud of inert smog,
which protects the tin and lead from oxidation. The soldered
connections were successful, but difficult to see under the carbonized
sticky mess. Removal required trichlorethane (auto brake cleaner) and
some elbow grease. Once cleaned, the connections looked quite shiny
and bright. Obviously, I missed a step in the production process, but
in general, it worked.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" wrote in message
...
"Arfa Daily" hath wroth:

Just as a matter of interest, I always remove rosin flux residues from
boards, using a proprietory flux remover from Electrolube. IMHO, post
soldering residues left on boards make the job look scrappy and
unprofessional.

http://en.wikipedia.org/wiki/Soldering
http://www.finishing.com/Library/flux.html
http://www.worldwideflood.com/ark/pitch/pitch.htm

Ignoring acid flux, the rosin fluxes come in two flavors. Water based
and those that require some solvent to remove. Water based fluxes can
allegedly be left on the board and will not eat the copper traces. The
inspiration for this was not to reduce cleanup costs, but because of
environmental and workplace regulations which proscribed the use of
chlorinated hydrocarbon solvents for board cleaning.

The problem is that water soluble fluxes require rather hot water to
remove properly. They're mostly used wave solder machines and not
hand soldering. However, we were using them on the production in
rework stations and of course, I ended up with a few rolls of the
stuff. That's when I discovered that if you leave the flux on the
board for more than a few days, it turns rock hard and no amount of
hot water will get rid of it. The residue is water soluable, but the
big lumps left in rework are not. I experimented with some household
cleaners and found the ammonia cleaner sorta works. It's often easier
to scrape the ossified flux off the board than to wash it as it's
quite brittle.

Another fun experiment was to make my own flux. I managed to
accidentally purchase a roll of solid core 63/37. No flux inside. I
could purchase a tub of Kester rosin solder paste, but that's too easy
and no fun. Rosin is just tree sap and I live in a forest with pine
trees and lots of sticky gooey sap. I just walk outside, scrape off
some pine sap, and I have instant rosin. I melted a big lump of the
stuff to clean it and boil off the volatiles, and voila, instant
sticky rosin flux.

When testing it, I found that the soldering iron was insufficient to
set the flux on fire, but did an adquate job of converting it into
noxious fumes. Rosin works by vaporizing into a cloud of inert smog,
which protects the tin and lead from oxidation. The soldered
connections were successful, but difficult to see under the carbonized
sticky mess. Removal required trichlorethane (auto brake cleaner) and
some elbow grease. Once cleaned, the connections looked quite shiny
and bright. Obviously, I missed a step in the production process, but
in general, it worked.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Ah ! See ... I knew there'd be someone out there that knew about the
chemistry of fluxes. Thanks for the info. Most interesting.

Arfa

"Arfa Daily" wrote in message ...
I'm a bit confused about the talk of not using acid fluxed solders in electronics. Just about all conventional solder wires formulated for electronic work, contain one or more cores of rosin based flux. As far as I am aware, this is a fundamentally acidic material when in its activated state, and in fact its being acidic is how it removes the tarnish and oxidation on the surfaces to be joined.

Afra -

In the United States, acid core (and not rosin core) was readily available for the plumbing trades (soldering copper water pipes)
When I started in 1970, it was easier for a newcomer to walk into a hardware store and purchase this formulation instead of rosin core (referred to as Radio-TV solder it that era).

While the problem has been greatly reduced, I still find a few amateurs commenting that they are using the same roll of solder they purchase many years ago -- for the copper water pipes in the house.

gb

wrote in message
ups.com...
Good thing I found this group and asked before I bought anything, the
guy at the store counter told me acid core is mainly used for
electronic work and at the other store, the salesperson said to use
rosin core. Thats what confused me; I bought the 63/37 tin/ lead rosin
yesterday and the soldering work turned out OK. Thanks for the help!
Phillip

Go back to store and tell manager to fire him (or shut him up)

gb

"g. beat" @spam protected hath wroth:

"Arfa Daily" wrote in message ...
I'm a bit confused about the talk of not using acid fluxed solders in electronics.
Just about all conventional solder wires formulated for electronic work,
contain one or more cores of rosin based flux. As far as I am aware, this
is a fundamentally acidic material when in its activated state, and in
fact its being acidic is how it removes the tarnish and oxidation on the
surfaces to be joined.

It's a question of quantity.

Both acid core and activated rosin flux contains ammonium or zinc
chloride. When heated, these produce hydrogen chloride gas (not
liquid) which disolves the copper, lead, and tin oxides and keeps the
solder joint clean. The metallic oxide is converted to zinc, metal,
and a salt. A detailed explanation can be found at:
http://yarchive.net/metal/soldering_flux.html

The difference is that the typical mildly activated rosin flux
generates hydrochloric acid vapor, not liquid. There's very little
acid in the flux and none in the residue. The bulk of the oxidation
protection is from the abietic acid in the rosin.
http://en.wikipedia.org/wiki/Abietic_acid
This effectively protects the copper from oxidation, but not the lead
or tin. That's what the hydrochloric acid smog from the activated
flux produces.

On the other hand, plumbers acid core flux contains the same ammonium
or zinc chloride, but in much larger quantities. There's plenty of
corrosive hydrochloric acid in the residue. That's the problem. Left
on the board, the acid will corrode everything. Just using such flux
around circuit boards will evaporate the acid, which will condense on
nearby components, and eventually corrode them.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" wrote in message
news
"g. beat" @spam protected hath wroth:

"Arfa Daily" wrote in message
...
I'm a bit confused about the talk of not using acid fluxed solders in
electronics.
Just about all conventional solder wires formulated for electronic work,
contain one or more cores of rosin based flux. As far as I am aware,
this
is a fundamentally acidic material when in its activated state, and in
fact its being acidic is how it removes the tarnish and oxidation on the
surfaces to be joined.

It's a question of quantity.

Both acid core and activated rosin flux contains ammonium or zinc
chloride. When heated, these produce hydrogen chloride gas (not
liquid) which disolves the copper, lead, and tin oxides and keeps the
solder joint clean. The metallic oxide is converted to zinc, metal,
and a salt. A detailed explanation can be found at:
http://yarchive.net/metal/soldering_flux.html

The difference is that the typical mildly activated rosin flux
generates hydrochloric acid vapor, not liquid. There's very little
acid in the flux and none in the residue. The bulk of the oxidation
protection is from the abietic acid in the rosin.
http://en.wikipedia.org/wiki/Abietic_acid
This effectively protects the copper from oxidation, but not the lead
or tin. That's what the hydrochloric acid smog from the activated
flux produces.

On the other hand, plumbers acid core flux contains the same ammonium
or zinc chloride, but in much larger quantities. There's plenty of
corrosive hydrochloric acid in the residue. That's the problem. Left
on the board, the acid will corrode everything. Just using such flux
around circuit boards will evaporate the acid, which will condense on
nearby components, and eventually corrode them.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Thank you both - more good stuff on the subject !

Arfa

On Wed, 07 Jun 2006 17:46:25 GMT, "ian field"
put finger to keyboard and composed:


wrote in message
oups.com...
I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Thanks


Lead free solder is specially formulated to fail after not more than 1 year
because the landfill sites aren't filling up with scrap electronic equipment
fast enough!!!

I find that metho leaves a white stain on some PCBs.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

On Sat, 17 Jun 2006 07:42:55 +1000, Franc Zabkar
opined:

[cleaning flux from PCBs]

I find that metho leaves a white stain on some PCBs.

Get out the meth's again & vigorously scrub the stained areas with an
old toothbrush. That usually does the trick for me.

Isopropyl alchohol is less likely to leave residue, but it costs a lot
more.
--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

[cleaning flux from PCBs]

I find that metho leaves a white stain on some PCBs.

Get out the meth's again & vigorously scrub the stained areas with an
old toothbrush. That usually does the trick for me.

Isopropyl alchohol is less likely to leave residue, but it costs a lot
more.

Not in the USA. 70% isopropyl alcohol (mixed with water, perfectly good for
defluxing) is 40 cents for 500 mL at the corner pharmacy.

How is isopropyl alcohol made and why is it so cheap and abundant in the USA
compared to other countries?

"mc" wrote in message
. ..
[cleaning flux from PCBs]

I find that metho leaves a white stain on some PCBs.

Get out the meth's again & vigorously scrub the stained areas with an
old toothbrush. That usually does the trick for me.

Isopropyl alchohol is less likely to leave residue, but it costs a lot
more.

Not in the USA. 70% isopropyl alcohol (mixed with water, perfectly good
for defluxing) is 40 cents for 500 mL at the corner pharmacy.

How is isopropyl alcohol made and why is it so cheap and abundant in the
USA compared to other countries?


The IPA normally sold for electronic purposes is very pure at 99.7% or
better. Lower grade rubbing alcohol is also abundant and cheap over here.
However, I have to say that the high grade stuff is not especially
expensive, and lasts a long time. I buy it in a 1 ltr tin, and one of those
lasts about a year in my shop. I don't use it for defluxing though. For
this, I buy an aerosol product from Servisol called "De-Flux 160". It comes
in a 200ml can and lasts me for a good six months. Only a tiny spray is
required, and with a stiff toothbrush, flux and other nasty deposits
disappear like magic.

Arfa