lead free solder

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View


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.


Re: lead free solder
On 30/04/2016 15:37, Ralph Mowery wrote:
Quoted text here. Click to load it

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.

Re: lead free solder
Quoted text here. Click to load it

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.



Re: lead free solder
Ralph Mowery wrote:


Quoted text here. Click to load it
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

Re: lead free solder
On Saturday, April 30, 2016 at 2:00:53 PM UTC-4, Jon Elson wrote:
Quoted text here. Click to load it

Me too, the amalgamate talk makes me wonder though.  

George H.  
Quoted text here. Click to load it


Re: lead free solder


Quoted text here. Click to load it

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.  


Re: lead free solder
snipped-for-privacy@ntlworld.com says...
Quoted text here. Click to load it

I had a RCA (think that was the brand) that had a classic case of bad  
solder around the tuner. This was in the days before the internet,but  
there was the FIDO net that I found the solution of the problem.   Went  
over the solder around the tuner and it was good for about 2 years and  
then had to do it again.  Not sure what kind of solder was used way back  
then as it was over 20 years ago.  Seems that RCA had many solder issues  
around tht period of time.  Should have been a total recall for them.
Last thing I bought with the RCA name on it.





Re: lead free solder


Quoted text here. Click to load it

AFAICR: RoHS came in about 96. It probably isn't law in America and Asia,  
but they have to comply if they want to export to Europe.

Certification is expensive - and much more expensive if they also run a non  
RoHS production line, as they have to prove that cross contamination cant  
happen.

Last time I checked - RCA had been taken over by the French Thomson firm.

Last Hitachi I looked inside; the innards were made by the Turkish Vestel  
company - while researching servicing info; I learned that quite a few big  
name manufacturers stick their badge on the very same chassis I found.  


Re: lead free solder
snipped-for-privacy@ntlworld.com says...
Quoted text here. Click to load it

That is one big problem for me.  I never know who or where anything is  
really made.  I was repairing some CB radios for friends around 1970 and  
found even then the same insides were put into different cabinets for  
different brands.  Sometimes even the same color wires were used.

The Brand names are often sold and moved to a different country so the  
quality may or may not be worse.

Sometimes it gets as bad as the Jeep.  From what I heard you almost need  
to know the day it was made to find out what kind of engine or  
transmission was used in it.  




Re: lead free solder


Quoted text here. Click to load it

AFAIK: there's wheelers & dealers brokering brand names.

Bush wasn't the Rolls Royce of consumer electronics, but it was a well  
respected brand. Its now one of quite a few badges that get stuck on very  
cheap & very nasty Vestel equipment like the one I found.  


Re: lead free solder
On Monday, May 2, 2016 at 2:09:22 PM UTC-4, Ian Field wrote:
Quoted text here. Click to load it

Thanks Ian,  I'm a bit confused by your response though.  
It's starts by saying 60/40 on lead free is dodgy,  
and ends by saying you had few problems when using it.  

George H.  

Re: lead free solder
On 03/05/2016 13:25, snipped-for-privacy@gmail.com wrote:
Quoted text here. Click to load it

60/40 on lead free is dodgy, PbF is dodgey, PbF on PbF is dodgey, SAC on  
PbF is dodgey, you do your own thing with fingers crossed and monitor  
for bouncers over the next few years.

Re: lead free solder


Quoted text here. Click to load it

They do seem to be getting better at lead free - at one point, the bulk of  
TVs going to landfill increased five-fold because of dodgy soldering. They  
are gradually getting that figure down a bit.

Apart from the fact that manufacturing was taking lead out of the  
environment and binding into a relatively stable alloy - what difference is  
RoHS going to make with rain and hail lashed lead roofs running into the  
water table. There's been about 100 yrs of the landed gentry peppering  
agricultural land with lead shot. They're most unlikely to have got all the  
lead pipes that were used upto the 50s - in the UK; they're still  
discovering Roman lead water ducting.

The other side of the coin was lead in petrol - the petrochemical industry  
lead procurement was in tons, and the number had a lot of noughts on the  
end. That lead was being pumped in the air as particulates for us all to  
breathe.  


Re: lead free solder

Quoted text here. Click to load it

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

Re: lead free solder
snipped-for-privacy@aol.com says...
Quoted text here. Click to load it

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.




Re: lead free solder
Fred McKenzie wrote:

Quoted text here. Click to load it
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

Re: lead free solder
systems.com says...
Quoted text here. Click to load it

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.



Re: lead free solder
Ralph Mowery wrote:


Quoted text here. Click to load it
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

Re: lead free solder
"Amalgamates" *Does Not* mean that an alloy has been formed. An Amalgam is  
essentially a solid colloid whereby the *separate* properties of the compon
ents makes a mixture that does not behave as either. The best example of th
is that is easily understood is Dental Amalgam, which is a mixture of silve
r, 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 disp
laced and the rest of the mixture hardens. But, it is NOT an alloy. The var
ious 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 i
f 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, i
f you must, somewhat like concrete. The components, sand, gravel, water, an
d 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 rem
ains 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 otherw
ise degrading. If it is attacked by something, that something will be quite
 toxic or dangerous in its own right. Those compounds would include chlorin
e, 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 ka
rat (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  - ja
cks, 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  


Re: lead free solder
snipped-for-privacy@aol.com says...
Quoted text here. Click to load it
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.  
Quoted text here. Click to load it


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.

Site Timeline