lead free solder

[Ralph Mowery]

I am in the US and just doing my own repairs and building.

Do I need to use any of the lead free solder to repair the boards that
were made usign the lead free solder?

I have not bought any yet and have been practicing witht he SMD on old
computer boards. That stuff seems a pain to work with compaired to the
'regular' tin/lead that I have been using for the last 50 years.

I have been thinking about getting some for the power transistors and
resistors where there is a lot of heat build up but not sure if that
application would even be worth the trouble.

 

[N_Cook]

On 30/04/2016 15:37, Ralph Mowery wrote:

I am in the US and just doing my own repairs and building.

Do I need to use any of the lead free solder to repair the boards that
were made usign the lead free solder?

I have not bought any yet and have been practicing witht he SMD on old
computer boards. That stuff seems a pain to work with compaired to the
'regular' tin/lead that I have been using for the last 50 years.

I have been thinking about getting some for the power transistors and
resistors where there is a lot of heat build up but not sure if that
application would even be worth the trouble.

If you are just doing repairs or mods to PbF stuff then use SAC (Tin
+Silver+Copper) solder, the cost would be prohibitive for complete new
build soldering.

 

[Ralph Mowery]

In article <ng2iej$oba$1@dont-email.me>, diverse@tcp.co.uk says...

On 30/04/2016 15:37, Ralph Mowery wrote:


I am in the US and just doing my own repairs and building.

Do I need to use any of the lead free solder to repair the boards that
were made usign the lead free solder?

I have not bought any yet and have been practicing witht he SMD on old
computer boards. That stuff seems a pain to work with compaired to the
'regular' tin/lead that I have been using for the last 50 years.

I have been thinking about getting some for the power transistors and
resistors where there is a lot of heat build up but not sure if that
application would even be worth the trouble.


If you are just doing repairs or mods to PbF stuff then use SAC (Tin
+Silver+Copper) solder, the cost would be prohibitive for complete new
build soldering.

As I would not use a pound every few years, the cost would not be a
problem for me. For the very small solder I doubt I would use a pound
of the lead free solder for the rest of my life.

As it is just for my own use at home I am not worried about the legal
Rohs part.

While the above seems like dumb questions, I find it is easier to ask
than spend all day looking for the answers.

I did see where some of the water clean up flux says that it can be left
on and some of it says it is safe for a few dys so I am going to stay
away from that. Reminds me of the old acid flux. May be ok to use if
cleaned off, but absolutly can not be left on if used. Even then I wold
never use it on anything but pumbing.

 

[Fred McKenzie]

In article <MPG.318e8d38c906088989694@news.east.earthlink.net>,
Ralph Mowery <rmowery28146@earthlink.net> wrote:

I have not bought any yet and have been practicing witht he SMD on old
computer boards. That stuff seems a pain to work with compaired to the
'regular' tin/lead that I have been using for the last 50 years.

Ralph-

I sympathize!

The problem with using tin-lead solder with SMD, is that lead
"amalgamates" with the silver contacts of surface mount devices,
resulting in a non-conductive layer between the device and the circuit.

While tin-lead-copper solder may help, it would be better to use
lead-free. It may work better if you use a temperature-controlled iron,
capable of higher temperatures than your old iron.

Fred

 

[pfjw@aol.com]

"Amalgamates" *Does Not* mean that an alloy has been formed. An Amalgam is essentially a solid colloid whereby the *separate* properties of the components makes a mixture that does not behave as either. The best example of this that is easily understood is Dental Amalgam, which is a mixture of silver, tin, copper and zinc, indium and other materials *as a powder* mixed 1:1 with mercury. The mix is pressed into place, whereupon the mercury is displaced and the rest of the mixture hardens. But, it is NOT an alloy. The various components partially dissolve in the mercury and bind to each other as a result. Kinda-sorta like sticky bits of candy would bind to each other if made wet. But, the individual bits of candy never dissolve entirely, and except at the direct interface, could never be described as an alloy. Or, if you must, somewhat like concrete. The components, sand, gravel, water, and cement *cure* (NOT dry) into an amalgam - but they are NOT an alloy.

This is an obscure point, but important in this context. The potential for a non-conductive oxide to form is real as each component of the amalgam remains discrete in its behavior at the chemical level.

The reason that gold is used is that it is more resistant than any other of the noble metals to 'dissolving' into anything, forming an oxide or otherwise degrading. If it is attacked by something, that something will be quite toxic or dangerous in its own right. Those compounds would include chlorine, mercury, cyanide and reactants of same. Gold often does not solder well, true, but that depends much on how how it is alloyed and its purity. 24 karat (pure) gold tends to solder quite easily, if gotten hot enough, but is also very expensive, very soft and for those reasons seldom used. 10 karat gold - the lowest that can still be called 'gold' solders badly unless very high silver-content solder is used, and typically requires a flame. Silver Brazing would be a better description.

Gold is seldom used in soldered components as there is no reason to do so. The only real reason for gold (as it is a poor conductor relative to silver or copper) is its resistance to corrosion on contact-type connectors - jacks, plugs and switches. Soldering *to* a gold-flashed lug or pad is asking for trouble for all sorts of reasons, some obvious, some not so much.

This is basic high-school chemistry - at least when I was in school.

Peter Wieck
Melrose Park, PA

 

[Ralph Mowery]

In article <fmmck-785AB7.12474930042016@46.sub-75-242-165.myvzw.com>,
fmmck@aol.com says...

In article <MPG.318e8d38c906088989694@news.east.earthlink.net>,
Ralph Mowery <rmowery28146@earthlink.net> wrote:


I have not bought any yet and have been practicing witht he SMD on old
computer boards. That stuff seems a pain to work with compaired to the
'regular' tin/lead that I have been using for the last 50 years.

Ralph-

I sympathize!

The problem with using tin-lead solder with SMD, is that lead
"amalgamates" with the silver contacts of surface mount devices,
resulting in a non-conductive layer between the device and the circuit.

While tin-lead-copper solder may help, it would be better to use
lead-free. It may work better if you use a temperature-controlled iron,
capable of higher temperatures than your old iron.

Fred

Ok Fred, thanks for explaing the 'amalgamates' part. Looks like I will
be getting some of the lead free solder. I know the old gold plated RF
power transistors gave a lot of problems due to the gold plating of the
leads, so guess the lead free boards are doing something similar.

I do have a couple of temperature controlled irons. Also bought one of
the hot air gun and soldering pencil stations. Just an inexpensive one
for about $ 65 off Ebay. Seems to work well on the regular leaded SMD
boards. I have been running the irons up much higher to match the lead
free boards.

I have been looking at a lot of the Youtube vids about the SMD soldering
and they make it look easy. The boards with the tin/lead solder I have
been practicing on usually turn out very well, not so much for the lead
free stuff. I do have one small tube of solder that has some silver in
it but not sure what else. I need to look it up on the internet and see
what it is actually made of. It is some from some samples we got when I
was working and no one ever used. The tube does not state the makeup,
just thatit has some silver in it.

 

[Jon Elson]

Ralph Mowery wrote:

As it is just for my own use at home I am not worried about the legal
Rohs part.

OK, just for your own use, you can do repairs with PbSn solder on assemblies
made originally with Pb free. I do this all the time, never had a problem.

You can also, in most cases, do repairs on gear that was made with PbSn
solder using SAC305. This does require higher temperatures, but when hand
soldering one lead at a time, usually there's no harm.

Jon

 

[Jon Elson]

Fred McKenzie wrote:

In article <MPG.318e8d38c906088989694@news.east.earthlink.net>,
Ralph Mowery <rmowery28146@earthlink.net> wrote:


I have not bought any yet and have been practicing witht he SMD on old
computer boards. That stuff seems a pain to work with compaired to the
'regular' tin/lead that I have been using for the last 50 years.

Ralph-

I sympathize!

The problem with using tin-lead solder with SMD, is that lead
"amalgamates" with the silver contacts of surface mount devices,
resulting in a non-conductive layer between the device and the circuit.

While tin-lead-copper solder may help, it would be better to use
lead-free. It may work better if you use a temperature-controlled iron,
capable of higher temperatures than your old iron.

Actually, if it amalgamates, you are fine. That essentially means it has
made an alloy. Pbf component leads usually do NOT have silver on them, just
Tin. Now, GOLD is a problem, a certain percent of gold dissolved into a
solder joint can cause brittle structures that fracture under thermal or
mechanical stress. They call this intermetallics. But, I've never heard of
this with silver. I've done tons of boards with SMDs using PbSn solder, and
had no trouble with it. One time ONLY, I got talked into trying gold flash
plating on the circuit boards, and had HUGE problems with joints that never
flowed, or became brittle. The fix was, desolder, lift the lead, scrape the
pad down to bare copper, tin the pad, fold the lead back down and solder.
UGGGH! Still gives me nightmares!

Jon

 

[Ralph Mowery]

In article <uYWdnX3VN86PabnKnZ2dnUU7-aXNnZ2d@giganews.com>, elson@pico-
systems.com says...

Fred McKenzie wrote:

In article <MPG.318e8d38c906088989694@news.east.earthlink.net>,
Ralph Mowery <rmowery28146@earthlink.net> wrote:


I have not bought any yet and have been practicing witht he SMD on old
computer boards. That stuff seems a pain to work with compaired to the
'regular' tin/lead that I have been using for the last 50 years.

Ralph-

I sympathize!

The problem with using tin-lead solder with SMD, is that lead
"amalgamates" with the silver contacts of surface mount devices,
resulting in a non-conductive layer between the device and the circuit.

While tin-lead-copper solder may help, it would be better to use
lead-free. It may work better if you use a temperature-controlled iron,
capable of higher temperatures than your old iron.
Actually, if it amalgamates, you are fine. That essentially means it has
made an alloy. Pbf component leads usually do NOT have silver on them, just
Tin. Now, GOLD is a problem, a certain percent of gold dissolved into a
solder joint can cause brittle structures that fracture under thermal or
mechanical stress. They call this intermetallics. But, I've never heard of
this with silver. I've done tons of boards with SMDs using PbSn solder, and
had no trouble with it. One time ONLY, I got talked into trying gold flash
plating on the circuit boards, and had HUGE problems with joints that never
flowed, or became brittle. The fix was, desolder, lift the lead, scrape the
pad down to bare copper, tin the pad, fold the lead back down and solder.
UGGGH! Still gives me nightmares!

Jon

I have ran into the gold problem. Only "simple" cure I know of is to
just scrape it to the base material.
I never gave the solder any other thought before just use the 60/40 or
beter if around 63/37 and rosin flux, but now with that lead free stuff
comming in and components having to be made to the Rohs standards it is
time to do some asking about the mechanics of it. Seems there are about
half a dozen or more mixes now without the lead.

There is one other problem I have seen , not with solder, but tin plated
items. The tin "whiskers'. Probably will be a problem with the
tin/silver and no lead solder. I have read that the military and space
agencies still use the tin/lead to not have that problem.

I know I have to use a lot more heat on the irons on that lead free
stuff.

 

[Ian Field]

"Ralph Mowery" <rmowery28146@earthlink.net> wrote in message
news:MPG.318e8d38c906088989694@news.east.earthlink.net...

I am in the US and just doing my own repairs and building.

Do I need to use any of the lead free solder to repair the boards that
were made usign the lead free solder?

Within the EU; hobby use and repairing originally lead solder equipment is
among the exemptions.

Never bothered swotting up on the laws elsewhere, but I think America and
Asia comply with RoHS purely so they can export to the EU.

RoHS certification is expensive enough, but certification guaranteeing that
cross contamination can't happen in a manufacturing plant that uses both
processes, is much more costly - its much cheaper to impose blanket
compliance with RoHS, even for goods that don't have to comply.

Mixing them depends on individual compositions - visual appearance of the
finished joint is a good indication whether you got away with it.

 

[Ralph Mowery]

In article <a6c4d91d-e647-4d3f-9e76-5890eeeca3fe@googlegroups.com>,
pfjw@aol.com says...

The reason that gold is used is that it is more resistant than any other of the noble metals to 'dissolving' into anything, forming an oxide or otherwise degrading. If it is attacked by something, that something will be quite toxic or dangerous in its own right. Those compounds would include chlorine, mercury, cyanide and reactants of same. Gold often does not solder well, true, but that depends much on how how
it is alloyed and its purity. 24 karat (pure) gold tends to solder quite easily, if gotten hot enough, but is also very expensive, very soft and for those reasons seldom used. 10 karat gold - the lowest that can still be called 'gold' solders badly unless very high silver-content solder is used, and typically requires a flame. Silver Brazing would be a better description.

Gold is seldom used in soldered components as there is no reason to do so. The only real reason for gold (as it is a poor conductor relative to silver or copper) is its resistance to corrosion on contact-type connectors - jacks, plugs and switches. Soldering *to* a gold-flashed lug or pad is asking for trouble for all sorts of reasons, some obvious, some not so much.

I know gold is used in contacts because it is resistant to oxidation.
They really found that out when computers and memory chips were put
together with the tin contacts instead of gold. I have a ham radio
repeater made by GE that has some cards in it with the tin edge
connectors. About once or twice a year I have to pull them out and give
them a good cleaning. The low level audio stages seem to be the worse
and I have rewired the circuits to byapss those weak points. What I
never did understand is why most of the RF power transistors seem to
have gold leads. Most are soldered in and that solder joint often goes
bad for the reason you stated. Then you have to scrape off the gold and
remove the old solder and put fresh solder on.

 

[MJC]

In article <a6c4d91d-e647-4d3f-9e76-5890eeeca3fe@googlegroups.com>,
pfjw@aol.com says...

The reason that gold is used is that it is more resistant than any
other of the noble metals to 'dissolving' into anything, forming an
oxide or otherwise degrading. If it is attacked by something, that
something will be quite toxic or dangerous in its own right. Those
compounds would include chlorine, mercury, cyanide and reactants of
same.

I think I have mentioned "purple plague" here before.
https://en.wikipedia.org/wiki/Gold-aluminium_intermetallic. I learnt
about it decades ago when working on experimental conducting films.

I thought that gold was tricky to solder precisely because it did tend
to dissolve unless the solder was already loaded with gold.

Mike.

 

[Jon Elson]

Ralph Mowery wrote:

There is one other problem I have seen , not with solder, but tin plated
items. The tin "whiskers'. Probably will be a problem with the
tin/silver and no lead solder.

Pure tin solder, if not processed hot enough to anneal the Tin, can get REAL
bad. Part of the reason for the tin/silver solder is to reduce the whisker
formation, and it seems to work. I had some Xilinx chips which had pure tin
lead plating, and I was processing them at PbSn temperatures, and the LEADS,
not the solder joints, had whiskers at the bends in the leads, as this is
where the stressed tin was. Xilinx suggested hotter soldering temps.

Jon

 

[pfjw@aol.com]

On Saturday, April 30, 2016 at 6:00:05 PM UTC-4, MJC wrote:

I thought that gold was tricky to solder precisely because it did tend
to dissolve unless the solder was already loaded with gold.

Not really. Gold is also somewhat lubricious - and things flow well on it. BUT, they do not STICK well to it. Solder will flow and appear to be nice and tight, until it peels off like cheap tape. But it takes more than heat to cause gold to dissolve.

Peter Wieck
Melrose Park, PA

 

[Phil Allison]

pf...@aol.com wrote:

MJC wrote:

I thought that gold was tricky to solder precisely because it did tend
to dissolve unless the solder was already loaded with gold.

Not really. Gold is also somewhat lubricious - and things flow well on it. BUT, they do not STICK well to it. Solder will flow and appear to be nice and tight, until it peels off like cheap tape. But it takes more than heat to cause gold to dissolve.

** In fact gold dissolves readily in tin and hence solder.

Normally, gold plated parts have a nickel underlay which does not readily dissolve to form an alloy with solder. This results in joints that have poor mechanical strength.

https://en.wikipedia.org/wiki/Gold_plating#Soldering_issues

http://www.indium.com/blog/intermetallics-in-soldering.php


..... Phil

 

[pfjw@aol.com]

On Sunday, May 1, 2016 at 10:01:04 PM UTC-4, Phil Allison wrote:

pf...@aol.com wrote:

MJC wrote:

I thought that gold was tricky to solder precisely because it did tend
to dissolve unless the solder was already loaded with gold.

Not really. Gold is also somewhat lubricious - and things flow well on it. BUT, they do not STICK well to it. Solder will flow and appear to be nice and tight, until it peels off like cheap tape. But it takes more than heat to cause gold to dissolve.


** In fact gold dissolves readily in tin and hence solder.

Normally, gold plated parts have a nickel underlay which does not readily dissolve to form an alloy with solder. This results in joints that have poor mechanical strength.

https://en.wikipedia.org/wiki/Gold_plating#Soldering_issues

http://www.indium.com/blog/intermetallics-in-soldering.php


.... Phil

Phil:

Jewelry grade gold electroplate uses a three-metal process, first copper, then nickel, then gold. Electronic plating for other than switches and mechanical connectors DOES NOT go through this process as it would be far too costly, take too much time and often add too much thickness. We are discussing microns here, and they matter. Nor is appearance a concern. For flash plating electronic solder connectors, the gold is deposited directly on the copper.

http://download.springer.com/static/pdf/727/art%253A10.1007%252FBF03215398.pdf?originUrl=http%3A%2F%2Flink.springer.com%2Farticle%2F10.1007%2FBF03215398&token2=exp=1462192837~acl=%2Fstatic%2Fpdf%2F727%2Fart%25253A10.1007%25252FBF03215398.pdf%3ForiginUrl%3Dhttp%253A%252F%252Flink.springer.com%252Farticle%252F10.1007%252FBF03215398*~hmac=b8746d004d5b115705ea43a04cfe7c2dce17925447f5ab4a1bf7e5a965d0d81b

Is a link that will take you to an article on how gold operates at/less than one micron of thickness - whereupon you are correct, and at greater thicknesses, where the solder simply does not stick.

Gold is a wretched soldering base for electronic purposes using traditional tin-based solders. As I stated previously, for any number of reasons, some not obvious.

Peter Wieck
Melrose Park, PA

 

[Phil Allison]

pf...@aol.com wrote:


> Phil:

** That is patronising and offensive.

Address all posts to the NG.

Jewelry grade gold electroplate uses a three-metal process,

** Wrong topic.

For flash plating electronic solder connectors, the gold is
deposited directly on the copper.

** Is it ?

Gold is a wretched soldering base for electronic purposes using
traditional tin-based solders.

** That is a dramatic about face, if I ever saw one.




..... Phil

 

[pfjw@aol.com]

On Monday, May 2, 2016 at 8:45:29 AM UTC-4, Phil Allison wrote:

pf...@aol.com wrote:


** That is a dramatic about face, if I ever saw one.

Please show me where I have _ever_ endorsed, suggested or implied that gold is a useful soldering base for any sort of electronics purposes?

NASA has used gold as a soldering base in space and on the moon due to its tolerance of extreme heat, but they had to go to extraordinary lengths to make it reliable mechanically. Otherwise, not so much. Hence the cost per cubic centimeter of NASA equipment exceeds even that of the US military.

Silver-solder (real tin-free silver solder) is fine for gold, and why it is used for jewelry making. And as I also stated, silver brazing is more accurate as a flame is necessary typically - and in most cases, a flame is not appropriate for electronics.

Further to this, if one looks at what happens to very thin (=<1 micron) the gold "leaches" rather than dissolves - and may be easily recovered by any number of methods, not typical of a true solution. The heat breaks the plate bond to the copper substrate and the colloid so formed is very brittle.

http://mysite.du.edu/~jcalvert/phys/copper.htm

gives much more information on the chemistry (or lack thereof) of gold and as it compares to the other "noble" metals.

Peter Wieck
Melrose Park, PA

 

On Saturday, April 30, 2016 at 2:00:53 PM UTC-4, Jon Elson wrote:

Ralph Mowery wrote:


As it is just for my own use at home I am not worried about the legal
Rohs part.
OK, just for your own use, you can do repairs with PbSn solder on assemblies
made originally with Pb free. I do this all the time, never had a problem.

Me too, the amalgamate talk makes me wonder though.

George H.

You can also, in most cases, do repairs on gear that was made with PbSn
solder using SAC305. This does require higher temperatures, but when hand
soldering one lead at a time, usually there's no harm.

Jon

 

[Ian Field]

<ggherold@gmail.com> wrote in message
news:74505f62-dfcc-44f8-a54c-60772513be68@googlegroups.com...

On Saturday, April 30, 2016 at 2:00:53 PM UTC-4, Jon Elson wrote:
Ralph Mowery wrote:


As it is just for my own use at home I am not worried about the legal
Rohs part.
OK, just for your own use, you can do repairs with PbSn solder on
assemblies
made originally with Pb free. I do this all the time, never had a
problem.

Me too, the amalgamate talk makes me wonder though.

Reworking lead free with 60/40 sometimes gives a grainy finish that looks
even more dodgy than the original lead free.

When I was in TV repair, most Asian manufacturers had converted before most
people in the UK had even heard of RoHS. (but it took the Asian
manufacturers a lot longer to get it right).

My introduction to lead free solder was a steady stream of TVs with bizzare
random faults that defied any attempt at logical diagnosis - going over the
soldering fixed them as if by magic.

With Hitachi sets; you could push down on a component and the whole solder
fillet would detach from the other side, that revealed a thin black layer of
oxide on the copper.

On Sony sets; the solder looked as good as lead free ever can - but going
over the soldering fixed over 90% of all faults.

During that time I routinely used 60/40 - I didn't get many bounced repairs,
and not many of those had anything to do with solder.