Weller WTCPT tip not hot enough

[Bob Shuman]

Having worked in electronics assembly and manufacturing for many years, I
can confirm your assumption that all new production work gets wave soldered
and it has its own set of issues as evidenced by many cold solder joints
found in the field! That said, hand irons are still used for repairs...

Bob


"Jim Adney" <jadney@vwtype3.org> wrote in message
news:hho9b4tj2pqgath5n2ib7h8lv1suqfbm50@4ax.com...

Not sure what you're basing this on, since I doubt that any major
manufacturer is using irons in production. I would expect any real
production to be wave soldered for the last 20 years. I'm sure,
however, that wave soldering, with which I have no experience, has its
own set of problems.
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

 

[GMAN]

In article <EPadnSIPT6BCxSnVnZ2dnUVZ_gSdnZ2d@supernews.com>, "nobody >" <usenetharvested@aol.com> wrote:

Arfa Daily wrote:
"Jim Adney" <jadney@vwtype3.org> wrote in message
news:tgm6b4prg8tpsln65bf0teefbj4urs21o8@4ax.com...
On Sun, 24 Aug 2008 21:50:04 +0100 Eeyore
rabbitsfriendsandrelations@hotmail.com> wrote:

I prefer 800 degrees. Always have done. Esp with small tips. The idea is
to get
the soldering done as fast as quickly, not leave the joint cooking until
the
solder finally melts.
I have to disagree. 700 F is already way above the melting point of
the solder. If you need more heat you might want to use a larger tip,
with greater thermal mass, but higher temps are much more likely to
damage the board.

I've seen plenty of 'cold' / 'dry' joints arising from the use of 700F
tips. I
even told the manufacturing dept of a certain company to change to 800F
tips
for a certain process but they moaned that 'the tips wear out faster'. So
the
returns rate went up again Bloody idiots.
Good soldering technique will not give cold solder joints, regardless
of the tip temp. High tip temp is probably a poor way to overcome poor
technique.

I would absolutely dispute that statement


Using a higher temp iron will certainly pump more heat into
the joint in a given time, but it also results in more temp difference
across the joint, so you may be more likely to get what looks like a
good joint on the heated side, but with little penetration.

??

We've been using Rohs solder for quite a few years now, and I don't
have a bit of trouble with it using a 700 F tip.



I would suggest Jim, that it does rather depend on what exactly you are
soldering. If you are making consistently good lead-free joints with a 700
deg Weller tip in all circumstances, then you are doing a lot better than
most of the major manufacturers. Since they started using the stuff, the
service industry has seen a huge leap in bad joints - and not always in
'traditional' places where you might expect to find them.

Whilst you are correct in that a 700 deg tip melts lead-free solder, it does
not do so anything like as well as it does with leaded solder. Although
lead-free solder does not have as nice a melt / flow characteristic as
leaded in the first place, this undesirable quality is made much worse by
not having enough temperature on it - particularly when soldering a
component with a high thermal inertia, such as a connector or power
semiconductor. The fact that lead-free solder is much worse at wetting most
of the metals commonly used in electronic circuit construction, further
exacerbates the problem, and dictates that more aggressive fluxes are used
in the hateful stuff. Unless these are given the opportunity to do their
work, by allowing them to reach the temperatures they need to at the
soldering surface, then the likely result will be a bad joint - and one
that's invisible to the naked eye, and may not give trouble for some time,
at that. Many bad joints in lead-free that I come across in daily work, show
no signs of external distress at all (except that *all* lead-free joints
look distressed), and do not respond to tapping, freezing or heating. The
only conclusion has to be that whilst the solder has stuck ok to the copper
pad, it hasn't to the component leg inside the joint. Probably, a classic
example of the 'cold' joint that engineers your side of the pond, are fond
of calling them.

Use of a bigger tip to improve its own thermal inertia, is not an option
these days for general electronic service work. A finely pointed conical or
small screwdriver tip, is the order of the day. Component pin densities, and
component placement densities, are such that only a small tip and fine gauge
solder are appropriate in most cases, and it's just not a practical
proposition to keep changing tips, depending on what exactly is on your
bench at the time.

When Weller came up with the 700 deg tip, it was with a traditional tin lead
solder alloy in mind. It is the tip that has always been supplied with these
irons from new. Lead-free melts at a temperature of 30 to 50 deg F higher
than leaded, so based on Weller's determination of 700 deg being appropriate
for leaded solder, you would have to extrapolate this thinking to come up
with a tip temperature of perhaps 750 deg, which is what I have both my
variable temperature controlled station, and vacuum desoldering stations set
to, for lead-free work.

So I'm with Graham on this one (who is, like me, experienced in daily
soldering over many many years) in that for lots of lead-free work with a
Weller Magnastat iron, the best combination is a small tip, but with a lot
of heat behind it in the form of it being an 800 deg rated one. I don't
dispute that you can make good joints in lead-free with a 700 deg tip, as I
do it myself, but it does require very considerable care and experience to
'do it right'. There are now more appropriate soldering tools on the market
for lead-free work, than the good old TCP irons.

There are some interesting notes here about why the 'standard' tips burn out
quickly, when used with lead-free


http://www.cooperhandtools.com/europe/sales_literature/documents/Leadfree_Info
_GB.pdf

Arfa




Thanks, Arfa for the dissertation on RoHs solder. I'm lucky enough to
have had no dealings with the nasty stuff as most (as in 95%+) of the
repairs in newer stuff I work on is boardswap or exchange. I know I'll
eventually have to mess with it and miss the old leaded stuff I've been
doing since 1959...

I'll have to look up what Pace is doing for RoHs soldering and
desoldering tips.

At least I know my own home WTCPT unit will cope with RoHs solder in a
fashion.

This EU RoHs requirement for lead free solder is the precise reason the XBOX

360 has had such a high failure rate.

 

[N Cook]

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:48B5AFB5.F4F14EA5@hotmail.com...

N Cook wrote:

Arfa Daily wrote in message

One of the main reasons that manufacturers are having so much trouble
with
the stuff, is that they have to run their soldering processes at a
higher
temperature. This then brings them close to the maximums that some of
the
components can tolerate for any length of time, so they have to
compromise
and run the process at a slightly reduced temperature. That is fine
until
you have to solder a connector or power semiconductor - particularly
one
that is mounted on a heatsink, and that is where many lead-free bad
joints
are occuring. Trust me, if manufacturers didn't *have* to run their
processes at a higher temperature, with all of the implications of
that,
including a higher energy useage, to cope with lead-free, then they
wouldn't

Is all your info available collated together on a website somewhere. ?

Any comments on the following
If replacing new (ROHS) components to old boards (leaded solder) then
scrape
off most of the hard mirror-like finnish on the leads before tining with
and
then soldering with Pb-Sn solder

21Century RoHS boards , repair of but not production (heavy solder
usage),
use silver solder, or is that likely to lead to as much a problem as
mixing
RoHs and PbSn solder.

I read somewhere a while back that the military, aerospace and telecoms
guys
were sending components out to de 'de-tinned' of lead free and re-tinned
with
the proper stuff.

Crazy ! Otherwise you can get problems.

Graham

When you see brand new components with that hard shiny neat? tin finnish its
hardly surprising there is tin pest problems before anything to do with
microcracking in the solder. Not surprising that such components, after a
few months, can be pulled out by hand leaving neat square holes . It would
take a blow torch almost, to meld with that tin finnish, when on thick say
TOP3 leads.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[Arfa Daily]

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:48B5A902.F57DD3F7@hotmail.com...

Jim Yanik wrote:

"Arfa Daily" wrote
"Eeyore" wrote
Arfa Daily wrote:

I still use 700s because of the problem of 800s burning out quicker
when left idling all day,

I don't let that happen and re-tin and wipe the tip regularly. I
probably 'waste' as much solder as I use !

Plus Farnell IIRC sells some aggressive (iron) oxide remover that can
help restore a 'damaged' tip. It comes in a little circular tin.

I have some, and jolly good it is too, although I wonder just how much
that's eating away at the tip, as well ...

Did you never ever use ancient pure copper tips ? That's why Multicore
added
a small percentage of copper to some of their solders.


IIRC,that has some powdered solder mixed in with the flux.
It cleans AND tins.

That's the stuff.


(of course,AFAIK,it's not lead-free....)

Damn good news !

Graham

Aha ! When I first started in the business way back when dinosaurs roamed
the countryside, we used Adcola irons with a bakelite 'tortoiseshell'
handle, and a neat spiral of what looked like tinned copper wire wound right
up the length of the business end. Those irons used a solid copper tip, and
we always used 'Savbit' cored solder with them. This solder had added
copper, as you say. The best thing about those solid copper tips, was that
you could file them to any shape that suited your work, without compromising
their performance. A quick touch up with a file fully restored the soldering
tip, which would then tin immediately, and stay tinned until you flicked the
solder blob off, ready to start using it. The solid copper tips were, as I
recall, remarkably long lived, and could be filed into almost non-existence,
before they needed to be replaced. Using irons like that really taught you
the skills of good soldering, skills which stay with you your whole life.
The Antex CN15s and 25s from the same era also had solid copper tips, and
the same things applied. They were the first ones that I can remember
changing over to (first nickel ??) and then iron plating of the bits. Once
that plating wore through though, there was no rescuing the tip, even though
it was copper inside. Touching it up with a file was a one day only fix, and
a new bit was rapidly required. Odd that. perhaps the copper used was a
softer grade or something, once they had it 'protected' by the plating ...

Arfa

 

[Arfa Daily]

"N Cook" <diverse8@gazeta.pl> wrote in message
news:g93d6p$gu3$1@inews.gazeta.pl...

Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:n%9tk.26$oT7.2@newsfe10.ams2...

"N Cook" <diverse8@gazeta.pl> wrote in message
news:g92u87$1bf$1@inews.gazeta.pl...
Jim Adney <jadney@vwtype3.org> wrote in message
news:hho9b4tj2pqgath5n2ib7h8lv1suqfbm50@4ax.com...
On Tue, 26 Aug 2008 10:56:32 +0100 "Arfa Daily"
arfa.daily@ntlworld.com> wrote:


"Jim Adney" <jadney@vwtype3.org> wrote in message
news:tgm6b4prg8tpsln65bf0teefbj4urs21o8@4ax.com...
On Sun, 24 Aug 2008 21:50:04 +0100 Eeyore
rabbitsfriendsandrelations@hotmail.com> wrote:



Don't know about different types of lead-free solder.
But distinguishing lead free I've found is
1/ conical rather than domed solder joints
2/ putting a stainless steel sewing needle in some of the solder after
melting and extracting needle while still molten, it is much more
difficult
to remove the cold solder from the needle than doing the same with
leaded
solder.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/



And many boards now actually state that they are lead free or "PbF" on
the
silk screening. As far as I have been able to tell, it's not so much
about
mixing different types of lead-free alloys, which may or may not contain
small traces of other metals such as silver, but more a case of not
mixing
lead-free with leaded solder.

To Jim. All of my experience with this stuff is from a service rather
than
production point of view. You are of course right that manufacturers use
wave or reflow soldering, and have done for many years. The point I was
making about lead-free joints and Weller TCPs at 700 deg, versus
manufacturers' joints, was perhaps not grammatically well-made. What I
was
basically saying was that the manufacturers, with all of their expertise
and
expensive production soldering equipment, still can't get to grips with
the
stuff themselves, and are still producing equipment littered with bad
joints
from day one. So, if you are making consistently good 'production' joints
in
lead free, using 700 degree hand soldering equipment designed way way
before
any eco-prat had ever come up with the concept of taking the lead out of
solder, then you (your company) are doing, on average, better than the
big
boys.

As far as heat and temperature are concerned, I take your point that they
are not the same thing, and I don't think that I am confusing the two.
They
are however, inextricably linked to one another by external influences.
Energy, in the form of heat, is what has to be put into a body in order
to
raise its temperature. All solder has to have its temperature raised to
the
point where its liquid state becomes suitable for making a soldered
joint,
and then maintained at that temperature until the joint is completed. The
temperature at which this condition occurs for lead-free solder, is
higher
than that of leaded solder. If you are just making small joints, then
this
is of no consequence, and a 700 degree tip is fine for the job. With a
leaded joint - even a large one that causes the tip temperature to drop
by
a
few degrees - that drop is again of little consequence, as there is
plenty
of temperature 'overhead' available from a 700 deg tip. However, with
lead-free, 50 degrees of that overhead, have already gone, so if a joint
is
any bigger than 'small', the additional temperature drop at the tip,
caused
by the joint leaching heat from it, results in a less than adequate tip
temperature being maintained, to correctly complete the joint. The result
is
a bad or 'cold' joint. A 700 degree tip simply cannot maintain enough
heatflow into the solder, to keep it at a sufficient temperature to do a
'good job' on anything other than a small joint, and this is particularly
the case where a 'typical' repair workshop tip of small dimensions is
used.

I have a repair service for a particular board which uses lead-free, and
I
see many of them where the shop that's sending it back to me, have
attempted
some rework or component replacement, and it's quite obvious that they
have
been trying to use their normal leaded soldering equipment to do the job,
with the inevitable consequences.

I can accept what Cooper say about not being tempted to increase the tip
temperature, but I think that they are probably talking more about not
going
up far enough to get the same 'feel' with lead-free, as with leaded. Most
commentators on the subject, including soldering equipment manufacturers,
agree that a higher nominal tip temperature is required to work reliably
with lead-free.

One of the main reasons that manufacturers are having so much trouble
with
the stuff, is that they have to run their soldering processes at a higher
temperature. This then brings them close to the maximums that some of the
components can tolerate for any length of time, so they have to
compromise
and run the process at a slightly reduced temperature. That is fine until
you have to solder a connector or power semiconductor - particularly one
that is mounted on a heatsink, and that is where many lead-free bad
joints
are occuring. Trust me, if manufacturers didn't *have* to run their
processes at a higher temperature, with all of the implications of that,
including a higher energy useage, to cope with lead-free, then they
wouldn't
...

Arfa




Is all your info available collated together on a website somewhere. ?

Any comments on the following
If replacing new (ROHS) components to old boards (leaded solder) then
scrape
off most of the hard mirror-like finnish on the leads before tining with
and
then soldering with Pb-Sn solder

21Century RoHS boards , repair of but not production (heavy solder usage),
use silver solder, or is that likely to lead to as much a problem as
mixing
RoHs and PbSn solder.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

I don't have info particularly collated anywhere, but if you want to contact
me off group with an address that's monitored for input, I'll send you a
copy of the article, which contains references to where I got info, and who
from. I don't think that there is any particular need to remove the surface
of RoHS compliant components' leads. I seem to recall reading somewhere that
most component leads are now tin plated, as in coated in neat tin, rather
than being 'tinned' with any kind of solder, as they were in the past. A
coating of pure tin should not cause any problems when used with a
conventional SnPb solder. As far as using silver solder is concerned, I
don't believe that there is any need to go to those lengths. Given the
limited life and price of modern equipment, I think that any repair that
keeps a piece of kit going for another year is a result, and if the joint
that you made as part of the repair gives up after that time, then san fairy
ann ... Some commentators suggest using a lead-free alloy which contains a
small quantity of silver for hand work. These alloys have a melting point
closer to that of SnPb solder, and similar 'workability', but do of course,
cost significantly more, so I don't bother with them, for the same basic
reasons of equipment life / value.

On that score, just out of interest, I bought a little DVD player from the
local Tesco store last week. It's about the size of a portable player, but
without the LCD screen. It plays every format imaginable, gives a cracking
picture on my (CRT !) TV, and came with all leads and a very comprehensive
user guide in good english. It even has a full function 'credit card' remote
control. How much ? Fifteen quid !! ($27).

If it goes wrong, it's just toss-away. Don't care what solder it's made with
....

Arfa

 

[Arfa Daily]

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:48B5A81B.38F61A35@hotmail.com...

Arfa Daily wrote:

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
Arfa Daily wrote:

Just to be clear though, only mandated for items placed on the market
after June 2006, and which don't have a waiver. Items manufactured
prior to

that using conventional leaded solder, can continue to be repaired /
reworked
/ modified with leaded solder and non RoHS compliant components. New
items
for non commercial i.e. amateur use, can still be constructed in
whatever
component and solder technology you like.

Absolutely, although we have no idea what he's soldering. I still
prefer
800F tips for quick neat soldering.


I still use 700s because of the problem of 800s burning out quicker when
left idling all day,

Well I simply don't let it idle all day. It's guarenteed to give those
nasty
'inter-metallic oxides' in the long term anyway that make re-tinning near
impossible. A guy I used to work with would switch on the bench (including
iron)
and maybe not use the iron all day. Whenever I noticed, I'd switch it off
again.
Why waste electricity anyway ?

Graham

A few years back, it probaly wouldn't have bothered me, but the older I get,
the shorter the fuse I seem to have. If I were to pick up my iron to do some
soldering, and it wasn't instantly ready to use, I would just get mad at
having to wait for it. I actually don't keep my vacuum desoldering station
powered all the time now since I changed from the Weller to the Pace. The
Weller tips were about seven quid apiece, but lasted for ages, even with the
station left idling. The Pace tips are about the same price, but you have to
buy them five at a time, which hurts a bit more. Add to this that they don't
last above a few weeks when idling, and this has led me to only switch it on
when needed. However, it has to be said that whilst I am waiting for it to
hot up, I fume worse than lead-free solder flux, and tend to pick it up to
start using it as soon as the heat light has started flashing, which then
often results in a clog, as the tip hasn't reached full temperature right up
the (long on the Pace) pick up tube that is part of it ...

Arfa

 

[N Cook]

Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:vtmtk.28941$le1.19939@newsfe11.ams2...

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:48B5A902.F57DD3F7@hotmail.com...




Aha ! When I first started in the business way back when dinosaurs roamed
the countryside, we used Adcola irons with a bakelite 'tortoiseshell'
handle, and a neat spiral of what looked like tinned copper wire wound
right
up the length of the business end. Those irons used a solid copper tip,
and
we always used 'Savbit' cored solder with them. This solder had added
copper, as you say. The best thing about those solid copper tips, was that
you could file them to any shape that suited your work, without
compromising
their performance. A quick touch up with a file fully restored the
soldering
tip, which would then tin immediately, and stay tinned until you flicked
the
solder blob off, ready to start using it. The solid copper tips were, as I
recall, remarkably long lived, and could be filed into almost
non-existence,
before they needed to be replaced. Using irons like that really taught you
the skills of good soldering, skills which stay with you your whole life.
The Antex CN15s and 25s from the same era also had solid copper tips, and
the same things applied. They were the first ones that I can remember
changing over to (first nickel ??) and then iron plating of the bits. Once
that plating wore through though, there was no rescuing the tip, even
though
it was copper inside. Touching it up with a file was a one day only fix,
and
a new bit was rapidly required. Odd that. perhaps the copper used was a
softer grade or something, once they had it 'protected' by the plating ...

Arfa

You had it easy - when I started soldering it was a matter of heating , on
the gas stove, a shaped block of copper on a steel shaft with wooden handle.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[Arfa Daily]

"Jim Adney" <jadney@vwtype3.org> wrote in message
news:3i9cb4p93urfrm3bir5ub4hc5ls9l5ao7f@4ax.com...

On Wed, 27 Aug 2008 11:28:31 +0100 "Arfa Daily"
arfa.daily@ntlworld.com> wrote:

And many boards now actually state ...

<snip>

The board labeling certainly helps with the lead vs. lead free
problem, but the link you posted also states that the different lead
free alloys should not be mixed. The do seem to imply that mixing lead
in with the lead free is worse, but I can't tell whether the problem
there is an engineering problem or a legal one.

snip

.....ever come up with the concept of taking the lead out of
solder, then you (your company) are doing, on average, better than the big
boys.


We should all remember that the big boys also had soldering problems
before the lead free mandate. AFAIK, those problems were mainly due to
trying to run the boards over the wave soldering machines too fast. I
doubt that present day production quotas are any less compelling.

<snip>

..... A 700 degree tip simply cannot maintain enough
heatflow into the solder, to keep it at a sufficient temperature to do a
'good job' on anything other than a small joint, and this is particularly
the case where a 'typical' repair workshop tip of small dimensions is
used.


I'm glad to see that you do understand the difference between heat and
temperature, and the causes and effects of heat flow, but we won't
settle this argument until someone can post the actual melting point
of 63/37 and the solidus/liquidus of some of the lead free solders.
ISTR that the good old eutectic stuff melted at something like 370 F,
but I wouldn't bet on it. I'm pretty sure that it's somewhere below
400 F, so another 50 F is not such a big deal.

<snip>

... Most commentators on the subject, including soldering equipment
manufacturers,
agree that a higher nominal tip temperature is required to work reliably
with lead-free.

I don't find an actual tip temperature in the Weller link, but they do
say to use the lowest temperature possible. Since I find that I have
no trouble (really!) soldering with a 700 F tip, and everyone in our
lab uses the same irons with the same alloys, I see no reason why
anything hotter would be justified.

It is also quite true that I do not work under a quota requirement,
nor am I paid by the joint, so I don't mind if the joint takes 3
seconds instead of 2. OTOH, I'm not really much aware of any change in
my soldering habits or technique since I used my first WTCP iron in
about 1977.

<snip>

...Trust me, if manufacturers didn't *have* to run their
processes at a higher temperature, with all of the implications of that,
including a higher energy useage, to cope with lead-free, then they
wouldn't
...


I think they would do just as well if they ran more slowly at lower
temps, but they probably find that is even more expensive than the
higher temps.

We won't really know the answer until we know the actual liquidus
temps of the Rohs solders. A check here gives us some facts to
consider:

http://kester.com/en-US/technical/alloy.aspx

I note that most of these range from 420 to 450 F, with 2 eutectic
alloys that melt at 430 and 440. 700 F seems like plenty of overhead
for working at those ranges, at least to me.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

All points noted, and for the most part, agreed with. I think what I am
saying, and probably Graham too, if I understand him correctly, is that for
most modern service work, a small tip is needed, which is less than ideal
for transferring heat from the iron's element to the actual joint, which
should be being made by the joint itself being heated, and the solder 'fed
in', as is the case with leaded solder. The result of that less than ideal
sized tip is that inevitably, as a large joint leaches heat from it, the
temperature drops, perhaps 50 or more degrees. With leaded solder, this is
of little consequence, as the drop in temperature is still well above the
point where the solder is able to be worked, to create a guaranteed good
joint. However, that said, try it on a big enough joint, and that won't be
the case. With lead-free, the drop in tip temperature is of greater
significance, as it readily causes poor workability of the solder, a 50 or
more degree drop taking you a lot nearer to the point where the solder works
'pasty' rather than fluidly.

So in this case, a tip that starts off at 800 deg and then drops towards 700
'under load' appears to represent a tool better suited to the job 'on
average', bearing in mind that as service engineers, we are seeing many
types of equipment that need, in theory at least, a similar variety of
different soldering equipment. So what we are using is a working compromise,
that has to be able to cope with leaded as well as lead-free solder, and
everything from IC pins to BNC connectors or worse.

To some extent, the points raised are moot in that there are now much better
tools on the market for coping with the modern situation, without having to
compromise. Someone mentioned Metcal stations for instance. Any station with
a tight control loop, is much better than a TCP for general service work
these days. I run an Antex temperature adjustable station, which I keep
idling at about 680 degrees. I turn it up to 750 when using lead-free, as I
find from a purely personal point of view, that this temperature suits both
me, and the Ersin 306 alloy that I use. I still keep my TCP running, with a
700 deg tip mostly, more out of comfort as it has been with me many years,
but I do find that I use it less now.

As far as the manufacturers having trouble with the stuff goes, I don't
think that it is to do with deadlines per se. I can remember when PCBs were
first around, and the technology advanced very quickly, driven mainly by the
big Jap consumer market manufacturers, to the point where bad joints on
their equipment were virtually unheard of, and that has remained the
situation for many years now. Given that wave and reflow soldering were
fully mature and largely trouble free and reliable technologies, one would
have expected that the degree of understanding that they must have of the
processes involved, would have allowed them to slip seamlessly into
similarly reliable manufacturing with lead-free. This doesn't appear to have
been the case, and equipment is still coming out of factories with less than
satisfactory joints, which tells me that the problem is with the technology
itself, not how the manufacturers are incorporating it into their overall
manufacturing time budget. When push comes to shove, it is a replacement
technology that arguably wasn't required in the first place. The original
technology involved in soldering was the right one, as has been shown over
many years, and the replacement uses materials deemed to be ecologically
better, but which don't actually readily do the job that they are needed to.
The lead-free solder is being 'made to fit' on the back of the "green"
ticket if you will, and sod the consequences ...

Arfa

 

[Arfa Daily]

Is all your info available collated together on a website somewhere. ?

Any comments on the following
If replacing new (ROHS) components to old boards (leaded solder) then
scrape
off most of the hard mirror-like finnish on the leads before tining with
and
then soldering with Pb-Sn solder

21Century RoHS boards , repair of but not production (heavy solder
usage),
use silver solder, or is that likely to lead to as much a problem as
mixing
RoHs and PbSn solder.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/




I don't have info particularly collated anywhere, but if you want to
contact me off group with an address that's monitored for input, I'll send
you a copy of the article, which contains references to where I got info,
and who from.

On its way. Check your incoming. Let me know if any probs.

Arfa

 

[Arfa Daily]

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:48B67452.6C5678D1@hotmail.com...

Arfa Daily wrote:

I don't have info particularly collated anywhere, but if you want to
contact
me off group with an address that's monitored for input, I'll send you a
copy of the article, which contains references to where I got info, and
who
from. I don't think that there is any particular need to remove the
surface
of RoHS compliant components' leads. I seem to recall reading somewhere
that
most component leads are now tin plated, as in coated in neat tin, rather
than being 'tinned' with any kind of solder, as they were in the past. A
coating of pure tin should not cause any problems when used with a
conventional SnPb solder.

The military etc are still worried because of potential tin whiskers with
closely spaced device leads.

There are known examples of such inter-lead shorts and they can support up
to
30mA I read somewhere IIRC. I had a fantastic picture of one once. It
shorted
out a *crystal*.

Graham

Been some interesting stuff recently in Elektor mag on the subject, and how
the old AF117's used to fail in SO mixers used in early tranny radios. Seems
that was due to whiskers growing inside the metal can of the transistor,
which was tin plated, and shorting to the transistor itself. Many engineers
just used to snip the screen lead on the transistor, but I found that if you
quickly jabbed a screwdriver across between the screen and collector leads,
the short magically disappeared. I guess it was blasting off the microscopic
whisker by vapourising it.

Arfa

 

[Arfa Daily]

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
news:bPutk.129199$LU4.111647@newsfe24.ams2...

Is all your info available collated together on a website somewhere. ?

Any comments on the following
If replacing new (ROHS) components to old boards (leaded solder) then
scrape
off most of the hard mirror-like finnish on the leads before tining with
and
then soldering with Pb-Sn solder

21Century RoHS boards , repair of but not production (heavy solder
usage),
use silver solder, or is that likely to lead to as much a problem as
mixing
RoHs and PbSn solder.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/




I don't have info particularly collated anywhere, but if you want to
contact me off group with an address that's monitored for input, I'll
send you a copy of the article, which contains references to where I got
info, and who from.


On its way. Check your incoming. Let me know if any probs.

Arfa

Sent again using the first 'reserve' address. Let me know ...

Arfa

 

[N Cook]

Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:ASytk.66111$AE1.28777@newsfe28.ams2...

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
news:bPutk.129199$LU4.111647@newsfe24.ams2...


Is all your info available collated together on a website somewhere. ?

Any comments on the following
If replacing new (ROHS) components to old boards (leaded solder) then
scrape
off most of the hard mirror-like finnish on the leads before tining
with
and
then soldering with Pb-Sn solder

21Century RoHS boards , repair of but not production (heavy solder
usage),
use silver solder, or is that likely to lead to as much a problem as
mixing
RoHs and PbSn solder.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/




I don't have info particularly collated anywhere, but if you want to
contact me off group with an address that's monitored for input, I'll
send you a copy of the article, which contains references to where I
got
info, and who from.


On its way. Check your incoming. Let me know if any probs.

Arfa


Sent again using the first 'reserve' address. Let me know ...

Arfa

All received, not had a chance to read it yet

 

[Arfa Daily]

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:48B72619.6A544469@hotmail.com...

Arfa Daily wrote:

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message

The military etc are still worried because of potential tin whiskers
with
closely spaced device leads.

There are known examples of such inter-lead shorts and they can support
up
to 30mA I read somewhere IIRC. I had a fantastic picture of one once.
It
shorted out a *crystal*.


Been some interesting stuff recently in Elektor mag on the subject, and
how
the old AF117's used to fail in SO mixers used in early tranny radios.
Seems
that was due to whiskers growing inside the metal can of the transistor,
which was tin plated, and shorting to the transistor itself. Many
engineers
just used to snip the screen lead on the transistor, but I found that if
you
quickly jabbed a screwdriver across between the screen and collector
leads,
the short magically disappeared. I guess it was blasting off the
microscopic
whisker by vapourising it.

Now how did you devise that technique ?

Graham

Christ knows Graham ! I was about 18 at the time and probably about the only
one in the workshop who was reasonably comfortable with the new fangled
transistors ...

Thinking about it, the leads went E-B-Scr-space-C. It was probably one of
those fortuitous 'mistakes' where I was measuring the collector voltage, and
the meter probe slipped ...

Arfa

 

[N Cook]

Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:ndmtk.252459$Mn3.43603@newsfe30.ams2...

"N Cook" <diverse8@gazeta.pl> wrote in message
news:g93d6p$gu3$1@inews.gazeta.pl...
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:n%9tk.26$oT7.2@newsfe10.ams2...

"N Cook" <diverse8@gazeta.pl> wrote in message
news:g92u87$1bf$1@inews.gazeta.pl...
Jim Adney <jadney@vwtype3.org> wrote in message
news:hho9b4tj2pqgath5n2ib7h8lv1suqfbm50@4ax.com...
On Tue, 26 Aug 2008 10:56:32 +0100 "Arfa Daily"
arfa.daily@ntlworld.com> wrote:


"Jim Adney" <jadney@vwtype3.org> wrote in message
news:tgm6b4prg8tpsln65bf0teefbj4urs21o8@4ax.com...
On Sun, 24 Aug 2008 21:50:04 +0100 Eeyore
rabbitsfriendsandrelations@hotmail.com> wrote:



Don't know about different types of lead-free solder.
But distinguishing lead free I've found is
1/ conical rather than domed solder joints
2/ putting a stainless steel sewing needle in some of the solder
after
melting and extracting needle while still molten, it is much more
difficult
to remove the cold solder from the needle than doing the same with
leaded
solder.

I don't have info particularly collated anywhere, but if you want to
contact
me off group with an address that's monitored for input, I'll send you a
copy of the article, which contains references to where I got info, and
who
from. I don't think that there is any particular need to remove the
surface
of RoHS compliant components' leads. I seem to recall reading somewhere
that
most component leads are now tin plated, as in coated in neat tin, rather
than being 'tinned' with any kind of solder, as they were in the past. A
coating of pure tin should not cause any problems when used with a
conventional SnPb solder. As far as using silver solder is concerned, I
don't believe that there is any need to go to those lengths. Given the
limited life and price of modern equipment, I think that any repair that
keeps a piece of kit going for another year is a result, and if the joint
that you made as part of the repair gives up after that time, then san
fairy
ann ... Some commentators suggest using a lead-free alloy which contains a
small quantity of silver for hand work. These alloys have a melting point
closer to that of SnPb solder, and similar 'workability', but do of
course,
cost significantly more, so I don't bother with them, for the same basic
reasons of equipment life / value.

My experiences of RoHS, so far

For post 2006 repair work I use (lead-free) silver solder , despite it
leaving a grey "bad" looking joint. For an average repair, for me, this
costs to about 0.06 GBP/ 0.12 USD per job which is fine be me. Repeat,
repair not production or even re-work production. And very little
suck-it-and-see repair, tending to zero in on the errant component at the
first or second target, minimal trace cutting (consequential bridging
repair). At the moment about 20 percent lead-free jobs, as mainly old stuff
still. In years to come where it becomes obvious that complete, all
component, re-work is required then perhaps Ag would be too much of an
overhead.

Some of the bad joints i've seen in the last few years, you just do not come
across with leaded solder. And we're talking about kit only a year or two
old. eg totally unstressed (in temperature terms but subjected to vibration)
1/3 watt resistors (so no heatsinking at production) that you can pull out
of the "solder" joint by finger force.

No jobs have bounced back due to mixing of Ag and Pb-free solder (so far)

Likewise I must have repaired pre-2006 boards , that had early Pb-free
solder, using leaded solder in repair and likewise those jobs have not
bounced back, so far.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[N_Cook]

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:48B8DBD0.C09500F5@hotmail.com...

N Cook wrote:

Some of the bad joints i've seen in the last few years, you just do not
come
across with leaded solder. And we're talking about kit only a year or
two
old. eg totally unstressed (in temperature terms but subjected to
vibration)
1/3 watt resistors (so no heatsinking at production) that you can pull
out
of the "solder" joint by finger force.

Vibration is the killer with lead-free. Never mind the tin whiskers.

But did you also know about tin pest ? I have no idea how much the
temperature
is affected by the copper (and silver for the rich) in lead-free but the
Japs
also use bismuth IIRC.

" At 13.2 degrees Celsius (about 56 degrees Fahrenheit) and below, pure
tin
transforms from the (silvery, ductile) allotrope of ?-modification white
tin to
brittle, ?-modification grey tin. Eventually it decomposes into powder,
hence
the name tin pest.

The decomposition will catalyze itself, which is why the reaction seems to
speed
up once it starts; the mere presence of tin pest leads to more tin pest.
Tin
objects at low temperatures will simply disintegrate. "
http://en.wikipedia.org/wiki/Tin_pest

Graham

In the situation where you can just pull a component from a board, not
desoledered, it is sometimes possible to see a grey powdery surface to the
component, suggestive of tin-pest.

And for using tin tinned new RoHS components destined for both old boards
and Pb-Sn solder or new boards and silver solder, burr the tin off with a
"diamond" cintride burr on a Dremmel, before tinning with the intended
solder. A solid layer of tin is asking for trouble - turn to dust tin-pest.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[N Cook]

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:48B8DBD0.C09500F5@hotmail.com...

N Cook wrote:

Some of the bad joints i've seen in the last few years, you just do not
come
across with leaded solder. And we're talking about kit only a year or
two
old. eg totally unstressed (in temperature terms but subjected to
vibration)
1/3 watt resistors (so no heatsinking at production) that you can pull
out
of the "solder" joint by finger force.

Vibration is the killer with lead-free. Never mind the tin whiskers.

But did you also know about tin pest ? I have no idea how much the
temperature
is affected by the copper (and silver for the rich) in lead-free but the
Japs
also use bismuth IIRC.

" At 13.2 degrees Celsius (about 56 degrees Fahrenheit) and below, pure
tin
transforms from the (silvery, ductile) allotrope of ?-modification white
tin to
brittle, ?-modification grey tin. Eventually it decomposes into powder,
hence
the name tin pest.

The decomposition will catalyze itself, which is why the reaction seems to
speed
up once it starts; the mere presence of tin pest leads to more tin pest.
Tin
objects at low temperatures will simply disintegrate. "
http://en.wikipedia.org/wiki/Tin_pest

Graham

I'm not sure the critical temp is 13 deg C, has someone confused 13 deg F
and 13 deg C?. 13 degree C is quite a normal unheated room temperature.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[N Cook]

N Cook <diverse8@gazeta.pl> wrote in message
news:g9as2f$qlc$1@inews.gazeta.pl...

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:48B8DBD0.C09500F5@hotmail.com...


N Cook wrote:

Some of the bad joints i've seen in the last few years, you just do
not
come
across with leaded solder. And we're talking about kit only a year or
two
old. eg totally unstressed (in temperature terms but subjected to
vibration)
1/3 watt resistors (so no heatsinking at production) that you can pull
out
of the "solder" joint by finger force.

Vibration is the killer with lead-free. Never mind the tin whiskers.

But did you also know about tin pest ? I have no idea how much the
temperature
is affected by the copper (and silver for the rich) in lead-free but
the
Japs
also use bismuth IIRC.

" At 13.2 degrees Celsius (about 56 degrees Fahrenheit) and below, pure
tin
transforms from the (silvery, ductile) allotrope of ?-modification white
tin to
brittle, ?-modification grey tin. Eventually it decomposes into powder,
hence
the name tin pest.

The decomposition will catalyze itself, which is why the reaction seems
to
speed
up once it starts; the mere presence of tin pest leads to more tin pest.
Tin
objects at low temperatures will simply disintegrate. "
http://en.wikipedia.org/wiki/Tin_pest

Graham



I'm not sure the critical temp is 13 deg C, has someone confused 13 deg F
and 13 deg C?. 13 degree C is quite a normal unheated room temperature.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Its a time-temp-effect thing, must be less than 13.2 C to make any
appearance but

"As temperatures decrease below 13.2oC, the shift from the metallic
allotrope to the non-metallic allotrope progresses, reaching a maximum at
about -30oC (-22oF)."

http://dwb.unl.edu/Teacher/NSF/C10/C10Links/Chemistry.about.com/library/week
ly/aa040300a.htm


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[N Cook]

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:48B8F83D.2925C2B8@hotmail.com...

N Cook wrote:

I'm not sure the critical temp is 13 deg C, has someone confused 13 deg
F
and 13 deg C?. 13 degree C is quite a normal unheated room temperature.

Also see .....
http://findarticles.com/p/articles/mi_qa5348/is_200106/ai_n21473892

Which covers the popular manufacturing formula including 0.5% Cu.

Graham

Here is a pic I took of what was probably tin pest.
Ignore the top pic as just a control showing normal silvery appearance of
pins after desoldering.

http://home.graffiti.net/diverse:graffiti.net/solder.jpg
The black cap, the top pin could be pulled out and the bottom one needed
desoldering. It is just about possible to see the all grey dusty covering to
the top pin. So that 100 percent tin layer eventually turns to the grey form
, expanding in the process. So like a weed growing through concrete it
forces the solder apart as well as in itself being non-condusctive.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[N_Cook]

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:48B8F65B.649B2013@hotmail.com...

N_Cook wrote:

Eeyore wrote
N Cook wrote:

Some of the bad joints i've seen in the last few years, you just do
not
come across with leaded solder. And we're talking about kit only a year
or
two old. eg totally unstressed (in temperature terms but subjected to
vibration) 1/3 watt resistors (so no heatsinking at production) that you
can
pull
out of the "solder" joint by finger force.

Vibration is the killer with lead-free. Never mind the tin whiskers.

But did you also know about tin pest ? I have no idea how much the
temperature is affected by the copper (and silver for the rich) in
lead-free
but the
Japs also use bismuth IIRC.

" At 13.2 degrees Celsius (about 56 degrees Fahrenheit) and below,
pure
tin transforms from the (silvery, ductile) allotrope of
beta-modification
white
tin to brittle, alpha-modification grey tin. Eventually it decomposes
into
powder,
hence the name tin pest.

These phase changes are called allotropes.


The decomposition will catalyze itself, which is why the reaction
seems to
speed up once it starts; the mere presence of tin pest leads to more
tin
pest.
Tin objects at low temperatures will simply disintegrate. "
http://en.wikipedia.org/wiki/Tin_pest


In the situation where you can just pull a component from a board, not
desoledered, it is sometimes possible to see a grey powdery surface to
the
component, suggestive of tin-pest.

No surprise. A guitar amp kept in the garage will see those temps.


And for using tin tinned new RoHS components destined for both old
boards
and Pb-Sn solder or new boards and silver solder, burr the tin off with
a
"diamond" cintride burr on a Dremmel, before tinning with the intended
solder. A solid layer of tin is asking for trouble - turn to dust
tin-pest.

And whiskers.

The military etc are doing an enhanced version of what you describe.

Graham

Do you know of a precise term, military or civil, for the process of
mechanical (or other method) removal of full tin tinning of component legs,
prior to use ?

With that pic of tin-pested cap I should have said that the solder joints
otherwise looked normal, only this surface layer tinning of the pin had
transformed to grey.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[Arfa Daily]

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:48B8DA59.62E40190@hotmail.com...

Arfa Daily wrote:

"Eeyore" wrote
Arfa Daily wrote:

Been some interesting stuff recently in Elektor mag on the subject,
and
how the old AF117's used to fail in SO mixers used in early tranny
radios.
Seems that was due to whiskers growing inside the metal can of the
transistor,
which was tin plated, and shorting to the transistor itself. Many
engineers just used to snip the screen lead on the transistor, but I
found
that if
you quickly jabbed a screwdriver across between the screen and
collector
leads, the short magically disappeared. I guess it was blasting off
the
microscopic whisker by vapourising it.

Now how did you devise that technique ?

Christ knows Graham ! I was about 18 at the time and probably about the
only
one in the workshop who was reasonably comfortable with the new fangled
transistors ...

Thinking about it, the leads went E-B-Scr-space-C. It was probably one of
those fortuitous 'mistakes' where I was measuring the collector voltage,
and
the meter probe slipped ...

Unlike me designing power amps where a similar slip tends to result in a
lot of
magic smoke being let out.

Graham

Oh I had to work on them too ! Our company was responsible for background
music machines that were rented out ro shops etc. They used a sort of
cassette tape that was endless (!) in that it wound off the centre and back
on to the outside. Bit like an 8 track mechanism, but only had four tracks,
as I recall. Anyways, they had a bloody great amplifier built into them,
based on 2N3055s. Being an early design, there was no protection or bias
stabilization, and you only had to bring a 20k / volt meter near to some
points to get them to run away, releasing their magic smoke ... Happy days.
It's back when engineers learnt the business properly d:~}

Arfa