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Is this due to RoHS solder?

P

Paul Drahn

Jan 1, 1970
0
Took apart a Volvo 850 fuel pump relay. Cracks everywhere.

http://www.viatrack.ca/Misc/FP Relay/


Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place
It does look pretty bad. However, the cracks may not go very far into
the solder. You would have to carefully cut one of the connections apart
across a break and see haw far it does go.

When was the part manufactured. RoHS was not required until July 1996.
There have been many different formulations of lead-free solder. Most
have problems of one type or another. This could be one of the solders
that was discontinued for just the reason you see.

Paul
 
N

N_Cook

Jan 1, 1970
0
Boris Mohar said:
Took apart a Volvo 850 fuel pump relay. Cracks everywhere.

http://www.viatrack.ca/Misc/FP Relay/


Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place

RoHS came in with a vengence 2006, the earliest I've seen it in anything was
2001.
If you have some known tin+lead solder try adding it to a joint with a
soldering iron. If the surface goes white and the surface "freezes" almost
instantly then the original joint was likely PbF. If the original was
tin/lead then a near enough normal leaded solder joint will result. If you
have a temp settable soldering iron and set it low enough to still create a
leaded solder joint then you may find it takes an awful long time and
produce a pastey looking lump if you try the iron on a PbF solder joint with
a bit of flux to give it a decent chance of melting.
Just by appearance I would say you have PbF
This is a known PbF crack developing, in the body of a joint rather than
around a pin , a pic of mine
http://www.diverse.4mg.com/talk_crack.jpg
 
T

Tom Del Rosso

Jan 1, 1970
0
N_Cook said:
RoHS came in with a vengence 2006, the earliest I've seen it in
anything was 2001.

I was just going to ask how to identify RoHS but this thread made it
unnecessary.

I am now looking at an Antec PSU with no date except "copyright 2004."

If you have some known tin+lead solder try adding it to a joint with a
soldering iron. If the surface goes white and the surface "freezes"
almost instantly then the original joint was likely PbF. If the
original was tin/lead then a near enough normal leaded solder joint
will result.

I will try it.

If you have a temp settable soldering iron and set it
low enough to still create a leaded solder joint then you may find it
takes an awful long time and produce a pastey looking lump if you try
the iron on a PbF solder joint with a bit of flux to give it a decent
chance of melting.

That's exactly the kind of test I was going to ask about! Thanks.


--

Reply in group, but if emailing add one more
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..
 
C

Charles

Jan 1, 1970
0
"Boris Mohar" wrote in message


Took apart a Volvo 850 fuel pump relay. Cracks everywhere.


Some of the responses to your post are misleading. The dull, grainy look is
normal with lead-free solder.

The cracks are not necessarily a fault. Surface cracks that we can see,
often do not extend deep enough to cause problems.

In any case, soldered joints have indeed been compromised by the new
"improved" lead-free alloys!

Mixing politics and engineering will almost always yield bad decisions.


..
 
B

Boris Mohar

Jan 1, 1970
0
The Volvo fuel pump relay problem was widely known (amongst Volvo
owners) long before lead free solder was required.

Ron (Volvo owner)

Indeed. I have resoldered and brought back to life many of the white ones.
They were not RoHS, nevertheless the solder failed around relay armature
pins.
 
N

N_Cook

Jan 1, 1970
0
Tom Del Rosso said:
I was just going to ask how to identify RoHS but this thread made it
unnecessary.

I am now looking at an Antec PSU with no date except "copyright 2004."



I will try it.



That's exactly the kind of test I was going to ask about! Thanks.


--

Reply in group, but if emailing add one more
zero, and remove the last word.



.

Ignoring potentially dangerous chemical test here is another physical test,
perhaps not so conclusive.
Find a stainless steel sewing needle, must be st/st not ordinary steel. Try
poking the needle in a soldering iron made , molten pool of leaded solder ,
pulling out, with a blob on the needle.
Pull off using just a fingernail usually.
Repeat using PbF and you will probably need 2 pairs of pliers to pull the
blob off the needle
 
N

N_Cook

Jan 1, 1970
0
Charles said:
"Boris Mohar" wrote in message


Took apart a Volvo 850 fuel pump relay. Cracks everywhere.


Some of the responses to your post are misleading. The dull, grainy look is
normal with lead-free solder.

The cracks are not necessarily a fault. Surface cracks that we can see,
often do not extend deep enough to cause problems.

In any case, soldered joints have indeed been compromised by the new
"improved" lead-free alloys!

Mixing politics and engineering will almost always yield bad decisions.


.

This is why the likes of the aviation industry has a derogation to allow
continued use of leaded solder. Fuel pumps etc with PbF on a plane will soon
have them falling out of the sky.
They then have the problem of sourcing guaranteed PbF-free componentry ,
only single type production lines (PbF) around these days , generally
speaking , so insentive (serious mark-up) for a lot of fraudulent paperwork
and manifests etc , declaring the items are leaded when they are actually
PbF
 
C

Charles

Jan 1, 1970
0
"N_Cook" wrote in message
Charles said:
"Boris Mohar" wrote in message


Took apart a Volvo 850 fuel pump relay. Cracks everywhere.


Some of the responses to your post are misleading. The dull, grainy look is
normal with lead-free solder.

The cracks are not necessarily a fault. Surface cracks that we can see,
often do not extend deep enough to cause problems.

In any case, soldered joints have indeed been compromised by the new
"improved" lead-free alloys!

Mixing politics and engineering will almost always yield bad decisions.


.

This is why the likes of the aviation industry has a derogation to allow
continued use of leaded solder. Fuel pumps etc with PbF on a plane will soon
have them falling out of the sky.
They then have the problem of sourcing guaranteed PbF-free componentry ,
only single type production lines (PbF) around these days , generally
speaking , so insentive (serious mark-up) for a lot of fraudulent paperwork
and manifests etc , declaring the items are leaded when they are actually
PbF

It would be nice to live in a structured society where the governing system
reacts, but never over-reacts. And, this is really a dream, where
governments act proactively, before things go to shite.
 
S

Smitty Two

Jan 1, 1970
0
Boris Mohar said:
Took apart a Volvo 850 fuel pump relay. Cracks everywhere.

http://www.viatrack.ca/Misc/FP Relay/

Since my ears were burning, I'll toss in my tuppence. Looks to me like
leaded solder, poorly put together. Insufficient heat and or dwell time,
and insufficient flux. Looks hand-soldered to me, and looks as though
the assembler tried to compensate for insufficient heat and flux by
applying excessive solder.

Sure, the thing's in a hostile environment, and that could lead to
cracking, but the quality of the joints was never good, which makes them
more susceptible to hostile conditions.

My shop used to be across the street from my car mechanic, and he
brought me some god-awful automotive stuff. Don't remember which make it
was, but for years they used a relay board (box into which all the
relays plugged) that was an absolute abomination. Essentially about 10
layers of folded plastic with traces and pads on one side, all stacked
up together. A multi-layer "board" with god-awful soldering that just
could not be repaired after a few years of exposure to corrosives.
 
N

N_Cook

Jan 1, 1970
0
Jeff Liebermann said:
What year Volvo? The Volvo 850 was made from 1992 to 1997. This was
somewhat before RoHS solder was introduced en masse. Looking at the
photos and guessing by the age, methinks it's just a typical lead-tin
cracked solder joint produced by excessive vibration. It's not that
unusual for fuel pumps:
<http://www.volvoclub.org.uk/faq/EngineFuelinjection.html>
Scroll down to "Testing or Repairing Bad Fuel Injection Relay".
Also:
<http://www.tegger.com/hondafaq/mainrelayoperation/badmainrelay.html>
and others. Note the relay boards which look much like your photos.

In a past life, I used to design marine radios. We had solder
cracking problems on unsupported heavy parts (xformers, power
resistors, big electrolytics, etc) due to engine vibration and shock.
Oddly, the solution was NOT to support the part, because the load was
too great and would crack the glue. It was to decrease the size of
the PCB hole down to a tight fit. That would cause the vibrational
loads to be transferred to the PCB and therefore reduce the stresses
on the solder joint. With a large hole and fairly soft solder, the
solder tends to get extruded out of the hole eventually forming a
annual ring around the lead. (Hint: copper leads are harder and
stiffer than solder).

Somewhat later, we started using rubber washers and preforms under the
heavy components to help absorb the load. Imported electronics often
uses yellow acrylic goo to support top heavy parts, but makes rework
and quality control a PITA.

If you want to see how such a joint is formed, shove a heavy copper
component pin into a loose PCB hole and solder the pad. Find a
vibratory scraper or ultrasonic scaler that will accept a chuck. If
you have time, a vibrating toothbrush will do it after a few hours.
Connect the chuck or clamp to the wire lead. Vibrate until the lead
comes loose. You'll find that the crack somewhat resembles the
annular ring crack.


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


PCB holes somewhat larger than the component pins always, given time, would
cause ring cracks in solder but with PbF occurs in just a year or two. For
things like pcb mounted multi-terminal transformers they could have an extra
machining stage. A conical grinding or milling stage, per hole, on the side
that accepts the component so that larger holes could be avoided and still
not mess-up the hand alignment/placement due to microscopic , but in spec,
misalignment of the pins
 
B

Boris Mohar

Jan 1, 1970
0
Nope. Alloys do not crystallize unless the component metals separate.
That's not going to happen in a fairly short period of time. What
might happen after perhaps 30-50 years is the solder form "grains"
thus separating the tin and lead. Add a little electrolytic action at
the grain boundaries, and we have a crack.


Yep. The vehicle operating temperatures (-40C to +125C) are similar
to the mil spec electronics temp range (-55C to +125C).


Not thermal cycling. Copper and solder have almost the same coef of
thermal expansion:
solder = 13*10^-6 in/in/F
copper = 10*10^-6 in/in/F
The difference would need to be much more for the solder to
mechanically separate from the copper due to thermal expansion.

However, if the relay is mounted directly onto the PCB, with no
provisions for absorbing motion (shock or vibration), the combination
of PCB flex and mechanical stresses are going to break the joint. I've
seen PCB's where components will "retract" slightly when I hit the
connection with a soldering iron. That means the joint was
pre-tensioned or under stress from the original soldering and just
waiting to break. That's why I suggested a rubber washer or preform
under the big components.

Relay armature, diodes and resistors on this board are all clad Iron.
 
M

Mike Tomlinson

Jan 1, 1970
0
Boris Mohar said:
Took apart a Volvo 850 fuel pump relay. Cracks everywhere.

Date of manufacture 1996, so it's 16 years old. What do you expect?
 
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