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

http://www.viatrack.ca/Misc/FP%20Relay/


Regards,

Boris Mohar

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

void _-void-_ in the obvious place

On Dec 8, 3:37*pm, Boris Mohar wrote:
Took apart a Volvo 850 fuel pump relay. *Cracks everywhere.

http://www.viatrack.ca/Misc/FP%20Relay/

Regards,

Boris Mohar

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

void _-void-_ in the obvious place

Possibly.
It could also be the plating on the leads reacting with the Pb free
solder and causing a boundry cracking. I have seen this type of
problem since the late '50s and usually with the cheaper solders like
50-50 but even on Tektronix and HP equipment where better quality was
the norm.

Neil S.

On 12/8/2011 3:37 PM, Boris Mohar wrote:

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

http://www.viatrack.ca/Misc/FP%20Relay/


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

Boris Mohar wrote:
Took apart a Volvo 850 fuel pump relay. Cracks everywhere.

http://www.viatrack.ca/Misc/FP%20Relay/


Regards,

Boris Mohar




Looks like cold solder connections to me. Considering that the item with
the bad solder connections is the relay it could be that either it was
not soldered in well in the first place or that vibration that caused
its solder joints to fail.

If you reheat the solder connections and add some flux does it turn
shiny again?

Other possibilities spring to mind - lead/tin solder tinned leads then
installed with RoHS solder can produce bad joints too.

John :-#)#

--
(Please post followups or tech enquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

Boris Mohar wrote in message
...

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

http://www.viatrack.ca/Misc/FP%20Relay/


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

"Boris Mohar" wrote in message
...

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

http://www.viatrack.ca/Misc/FP%20Relay/


I thought automotive was exempt - after all you wouldn't want the solder
falling off your FI relay half way through an overtake.

On 09/12/2011 14:11, Ian Field wrote:
"Boris wrote in message
...

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

http://www.viatrack.ca/Misc/FP%20Relay/


I thought automotive was exempt - after all you wouldn't want the solder
falling off your FI relay half way through an overtake.


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

Ron (Volvo owner)

"Ian Field" wrote in
:


"Boris Mohar" wrote in message
...

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

http://www.viatrack.ca/Misc/FP%20Relay/


I thought automotive was exempt - after all you wouldn't want the solder
falling off your FI relay half way through an overtake.




Honda fuel pump relays have the same solder problems,have had them for many
years.
my 1994 Integra had it,I resoldered the PCB and it worked fine for many
years afterwards. I saved at least $50 for a few minutes work.

the relay failure mode was that on a hot day,the car would start
briefly,then die,and only crank for 15-20 minutes(no fuel pressure),then
the car would start and run normally(after the car's interior cooled
down).No further problem until it got another heat soak.
In the mornings,the car would start and run normally.

I think the solder crystallizes with age,then thermal cycling cracks it.

the automotive environment is very tough,hard on electronics.
lots of thermal cycling,shock and vibration.

--
Jim Yanik
jyanik
at
localnet
dot com

In article ,
says...

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

http://www.viatrack.ca/Misc/FP%20Relay/


Well if they are tin/lead, they are some of the best (worse???) examples
of cold solder joints I've ever seen. It is most likely some Pb free
stuff. Being brittle is pretty much SOP with SAC and the like. That's
why things like avionics and telecom are exempt. I guess being stranded
on the side of the road in January, in Montana, out in the middle of no
where would only kill one or two people...

N_Cook wrote:
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
zero, and remove the last word.



..

"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.


..

On Fri, 09 Dec 2011 14:24:11 +0000, Ron wrote:

On 09/12/2011 14:11, Ian Field wrote:
"Boris wrote in message
...

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

http://www.viatrack.ca/Misc/FP%20Relay/


I thought automotive was exempt - after all you wouldn't want the solder
falling off your FI relay half way through an overtake.


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.

--
Boris

Tom Del Rosso wrote in message
...

N_Cook wrote:
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
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

Charles wrote in message
...


"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

"Jim Yanik" wrote in message
4...
"Ian Field" wrote in
:


"Boris Mohar" wrote in message
...

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

http://www.viatrack.ca/Misc/FP%20Relay/


I thought automotive was exempt - after all you wouldn't want the solder
falling off your FI relay half way through an overtake.




Honda fuel pump relays have the same solder problems,have had them for
many
years.
my 1994 Integra had it,I resoldered the PCB and it worked fine for many
years afterwards. I saved at least $50 for a few minutes work.

the relay failure mode was that on a hot day,the car would start
briefly,then die,and only crank for 15-20 minutes(no fuel pressure),then
the car would start and run normally(after the car's interior cooled
down).No further problem until it got another heat soak.
In the mornings,the car would start and run normally.

I think the solder crystallizes with age,then thermal cycling cracks it.

the automotive environment is very tough,hard on electronics.
lots of thermal cycling,shock and vibration.

--
Jim Yanik
jyanik
at
localnet
dot com

Looking at the pictures, I think it is highly unlikely that the relay is
manufactured with lead-free solder. Although the joints have a somewhat
crystaline appearance, the surfaces of the individual 'grains' still appear
too shiny to be lead-free. Also, if you look at the shape of the joints,
they are much more conventional solder than lead-free solder. Whilst I would
agree that there is rather a lot of poor joints to be seen, again, I don't
see any that are typically consistent with a 'volcano' joint that you get
with lead-free. Annular cracks in the actual solder, rather than cracks
around the component lead where the solder has not taken to it, are far more
common with leaded solder. I would say that we are looking at a combination
of circumstances here, including age, temperature cycling and the generally
harsh automotive conditions that it lives in, relay hammer from the relay
operating many many thousands - if not millions - of times in its life so
far, and the possibility of the solder having been 'over-cooked' in the
first place. Smitty with his knowledge of production soldering may be able
to comment better than I on that.

Also, as Nigel says, the RoHS directive was not implemented with a vengeance
in most of Europe, until June 2006. That relay board is fully 10 years older
than that. Like him, I don't think that I have seen any electronic design
that old, that was implemented in lead-free solder.

Just as a matter of interest, I had a 1985 VW Passat for about 10 years. It
was the 2 litre version with the 5 cylinder Audi engine fitted. It had a
fuel pump actually inside the tank, and this was controlled by a relay on
the main board at the front of the car. Towards the end of the time I had
it, so probably around 1996, it started to suffer intermittent engine
stops - always in embarrassing places like four-way junctions, of course. It
would run for weeks without so much as a cough, then it would just die
without warning. Not too bad if you were tooling along on a big highway. It
just lost power and slowed down, giving you time to get off onto the side
shoulder, before you had no power at all, but worst was when you pulled away
from a stop light, and it just died ...

I discovered that you had to wait exactly four minutes - not a second less -
before turning the key and trying a restart. Invariably, it would then start
and run as though nothing had happened. It took me a long time to track the
problem down, but it eventually turned out to be bad joints in the fuel pump
relay. As I recall, it looked in pretty much the same state as the OP's one.

Arfa

"Arfa Daily" wrote in
:



"Jim Yanik" wrote in message
4...
"Ian Field" wrote in
:


"Boris Mohar" wrote in message
...

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

http://www.viatrack.ca/Misc/FP%20Relay/


I thought automotive was exempt - after all you wouldn't want the
solder falling off your FI relay half way through an overtake.




Honda fuel pump relays have the same solder problems,have had them
for many
years.
my 1994 Integra had it,I resoldered the PCB and it worked fine for
many years afterwards. I saved at least $50 for a few minutes work.

the relay failure mode was that on a hot day,the car would start
briefly,then die,and only crank for 15-20 minutes(no fuel
pressure),then the car would start and run normally(after the car's
interior cooled down).No further problem until it got another heat
soak. In the mornings,the car would start and run normally.

I think the solder crystallizes with age,then thermal cycling cracks
it.

the automotive environment is very tough,hard on electronics.
lots of thermal cycling,shock and vibration.

--
Jim Yanik
jyanik
at
localnet
dot com

Looking at the pictures, I think it is highly unlikely that the relay
is manufactured with lead-free solder. Although the joints have a
somewhat crystaline appearance, the surfaces of the individual
'grains' still appear too shiny to be lead-free. Also, if you look at
the shape of the joints, they are much more conventional solder than
lead-free solder. Whilst I would agree that there is rather a lot of
poor joints to be seen, again, I don't see any that are typically
consistent with a 'volcano' joint that you get with lead-free. Annular
cracks in the actual solder, rather than cracks around the component
lead where the solder has not taken to it, are far more common with
leaded solder. I would say that we are looking at a combination of
circumstances here, including age, temperature cycling and the
generally harsh automotive conditions that it lives in, relay hammer
from the relay operating many many thousands - if not millions - of
times in its life so far, and the possibility of the solder having
been 'over-cooked' in the first place. Smitty with his knowledge of
production soldering may be able to comment better than I on that.

Also, as Nigel says, the RoHS directive was not implemented with a
vengeance in most of Europe, until June 2006. That relay board is
fully 10 years older than that. Like him, I don't think that I have
seen any electronic design that old, that was implemented in lead-free
solder.

Just as a matter of interest, I had a 1985 VW Passat for about 10
years. It was the 2 litre version with the 5 cylinder Audi engine
fitted. It had a fuel pump actually inside the tank, and this was
controlled by a relay on the main board at the front of the car.
Towards the end of the time I had it, so probably around 1996, it
started to suffer intermittent engine stops - always in embarrassing
places like four-way junctions, of course. It would run for weeks
without so much as a cough, then it would just die without warning.
Not too bad if you were tooling along on a big highway. It just lost
power and slowed down, giving you time to get off onto the side
shoulder, before you had no power at all, but worst was when you
pulled away from a stop light, and it just died ...

I discovered that you had to wait exactly four minutes - not a second
less - before turning the key and trying a restart. Invariably, it
would then start and run as though nothing had happened. It took me a
long time to track the problem down, but it eventually turned out to
be bad joints in the fuel pump relay. As I recall, it looked in pretty
much the same state as the OP's one.

Arfa



interesting;
the Honda relay failure would not occur once the engine had started and was
running normally,possibly vibrations kept the solder joints "connected".
Others(on rec.autos.honda) have told me that smacking the relay would also
"get you going",until the next heat soak. Honda put their fuel relay("Main
relay") up under the dash on the drivers side. Not too bad to access for
removal/repair.

That Acura gave me a couple of "interesting" problems,the second was eroded
starter relay contacts,causing intermittent and unreliable cranking.
More than a couple of hundred bucks for a new starter(relay not
separate),but I found a "contact replacement kit" for $30 USD,and rebuilt
the relay myself.

--
Jim Yanik
jyanik
at
localnet
dot com

"N_Cook" wrote in message ...

Charles wrote in message
...


"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 ****e.

In article ,
Boris Mohar wrote:

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

http://www.viatrack.ca/Misc/FP%20Relay/



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.

On 10/12/2011 17:59, Arfa Daily wrote:



Just as a matter of interest, I had a 1985 VW Passat for about 10 years.
It was the 2 litre version with the 5 cylinder Audi engine fitted. It
had a fuel pump actually inside the tank, and this was controlled by a
relay on the main board at the front of the car. Towards the end of the
time I had it, so probably around 1996, it started to suffer
intermittent engine stops - always in embarrassing places like four-way
junctions, of course. It would run for weeks without so much as a cough,
then it would just die without warning. Not too bad if you were tooling
along on a big highway. It just lost power and slowed down, giving you
time to get off onto the side shoulder, before you had no power at all,
but worst was when you pulled away from a stop light, and it just died ...

I discovered that you had to wait exactly four minutes - not a second
less - before turning the key and trying a restart. Invariably, it would
then start and run as though nothing had happened. It took me a long
time to track the problem down, but it eventually turned out to be bad
joints in the fuel pump relay. As I recall, it looked in pretty much the
same state as the OP's one.

Arfa

Which are exactly the same symptoms which happen to pre Ford takeover Volvos

Ron

On Thu, 08 Dec 2011 18:37:06 -0500, Boris Mohar
wrote:

Took apart a Volvo 850 fuel pump relay. Cracks everywhere.
http://www.viatrack.ca/Misc/FP%20Relay/

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
# http://www.LearnByDestroying.com AE6KS

On Fri, 09 Dec 2011 08:31:16 -0600, Jim Yanik
wrote:

I think the solder crystallizes with age,then thermal cycling cracks it.

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.

the automotive environment is very tough,hard on electronics.

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

lots of thermal cycling,shock and vibration.

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.

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

Jeff Liebermann wrote in message
...
On Thu, 08 Dec 2011 18:37:06 -0500, Boris Mohar
wrote:

Took apart a Volvo 850 fuel pump relay. Cracks everywhere.
http://www.viatrack.ca/Misc/FP%20Relay/

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
# 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

On Mon, 12 Dec 2011 18:04:35 -0800, Jeff Liebermann wrote:

On Fri, 09 Dec 2011 08:31:16 -0600, Jim Yanik
wrote:

I think the solder crystallizes with age,then thermal cycling cracks it.

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.

the automotive environment is very tough,hard on electronics.

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

lots of thermal cycling,shock and vibration.

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.

--
Boris

On Tue, 13 Dec 2011 08:34:06 -0000, "N_Cook"
wrote:


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.

PbF is Lead Fluoride in chemical terms. Please find a better abrev.

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

It's been a while since I've ordered production PCB's, but as I
recall, the number of drill changes has a huge impact on the cost.
Auto manufacturers are VERY sensitive to costs. As a result, it's
more common to use cylindrical holes and wedge shapped component pins
on things like xformers and relays. These have the added bonus of
being self supporting during wave soldering.

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

In article , Boris Mohar
writes

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

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

--
(\__/)
(='.'=)
(")_(")

"Mike Tomlinson" wrote in message
...
In article , Boris Mohar
writes

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

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


Probably more than a 50yr old bakelite radio that the soldering was done
with a hearth poker style iron heated on a gas burner and rubbed on a block
of sal-ammoniac before tinning because the solder had no flux of its own.