Took apart a Volvo 850 fuel pump relay. Cracks everywhere.
Regards,
Boris Mohar
Got Knock? - see: Viatrack Printed Circuit Designs (among other things)
void _-void-_ in the obvious place
ca
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.
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
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 :-#)#
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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
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 news:JGoEq.112962$ snipped-for-privacy@newsfe20.ams:
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
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...
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.
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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
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
is
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
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 news:r5NEq.73360$ snipped-for-privacy@newsfe27.ams:
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
Which are exactly the same symptoms which happen to pre Ford takeover Volvos
Ron
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:
Scroll down to "Testing or Repairing Bad Fuel Injection Relay". Also:
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@cruzio.com # http://www.LearnByDestroying.com AE6KS
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.
-- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060 # 831-336-2558 # http://802.11junk.com jeffl@cruzio.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
Relay armature, diodes and resistors on this board are all clad Iron.
-- Boris
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