Is this due to RoHS solder?

"Jim Yanik" <jyanik_at_abuse.gov> wrote in message
news:Xns9FB660FF0FA2Djyaniklocalnetcom_at_216.168.3.44...
"Ian Field" <gangprobing.alien_at_ntlworld.com> wrote in
news:JGoEq.112962$CC2.47430_at_newsfe20.ams2:


"Boris Mohar" <borism_void__at_sympatico.ca> wrote in message
news:2ei2e75p1a6q0j3lkdb68h7ija4cfe7s5g_at_4ax.com...

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

"Boris Mohar" wrote in message
news:2ei2e75p1a6q0j3lkdb68h7ija4cfe7s5g_at_4ax.com...


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.


.

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

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

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

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

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.

On Thu, 08 Dec 2011 18:37:06 -0500, Boris Mohar
borism_void__at_sympatico.ca> 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 jeffl_at_cruzio.com
# http://www.LearnByDestroying.com AE6KS

On Fri, 09 Dec 2011 08:31:16 -0600, Jim Yanik <jyanik_at_abuse.gov
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.

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

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

In article <2ei2e75p1a6q0j3lkdb68h7ija4cfe7s5g_at_4ax.com>, Boris Mohar
borism_void__at_sympatico.ca> 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?