WEEE/RoHS/PbF rogues gallery

Careful ....

Arfa

Friend of mine rang me yesterday. He is an electronics engineer that works on fancy amplifiers used in mass spectrometry. These are mostly quite old as these things go on for ever, and the amps and things are just repaired and recalibrated, so he has not had to have much if any experience with the dreaded lead-free. A friend of his brought him a portable CD player to look at, which had apparently been working without any signs of trouble or intermittency, then just stopped.

My friend was amazed when he took the back off. An IC just fell out onto the bench. He couldn't believe that any production soldering could be so poor that this could happen, and he was ringing me to see if this was the sort of thing that we at the sharp end of this technology, were suffering. He was totally gobsmacked when I told him that was exactly the sort of thing we were experiencing, and his comment was "no wonder the military and avionics people won't use it !"

Makes you wonder how many other high-end engineers like my friend, have so far been shielded from the stuff, so have not had any dissenting voice in the forum ...

Arfa

at

as

look

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avionics

I've not seen a loose IC but I was surprised to find the simplest of components loose once - a pbf "soldered" wire link, ordinary 1/4W resistor gauge of wire. I'd like to know what that whitish-grey powdery deposit on the solder is, that makes these boards look as though they've been in a damp shed for years. Is it tin-pest, coming to the surface, the powdery allotrope of tin? that even medieval church organ builders were aware of.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

I see its the work of the devil, just googling, the first one

"The gradual disintegration of shiny tin metal into a crumbly, gray powder was observed hundreds of years ago on tin organ pipes housed in unheated northern European cathedrals. With allotropy unknown, the phenomenon was attributed to the work of the Devil and was variously denoted by the terms tin disease, tin pest, tin blight, or tin plague. The reaction is autocatalytic; in other words, the presence of the gray alpha-tin accelerates the process. Tin disease manifests itself in pure tin. Antimony, bismuth, or lead retards this transformation. Tin alloys are thus more resistant to tin disease."

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

I've seen a number of examples of ICs hanging on by a couple of pins, and have had a few where an IC has fallen off completely. Used to be a big problem with the audio IC in several Sony portable MD players, and also in a particular DAB radio that I used to have dealings with.

Arfa

I was reading up recently concerning damage due to the excessive heat for PbF soldering of pcbs. The most common fallout in immediate post-production test is multilayer ceramic caps

Is this delayed damage on this German made Dynacord mixer amp, definitely using pbf construction.? A 100nF, 100V cap incinerated itself , in an area that did not affect routine use of the amp. The failure of the amp was due to another of this batch of capacitors with less than 20V standing DC, going ohmic, measuring of order 20K to 30K with a DVM when I measured it but varying considerably. in the parts list as KO-KER 0.10MF 100V 20% cap ceramic 100nF it is mustard yellow epoxy cased, axial leaded, 2.2mm diameter, 3.5mm long at longest axial dimension, with markings (requiring x30 microscope to read, and not that clear, so maybe wrong transcription) R1E

104 for 100nF and 619 for week 19 of 2006, R1E for 100V ? I've not found the manufacturer yet under KO-KER or MGR yet, but I assume from the size that they are multilayer ceramic.

I can of course replace these 2 but what about the remaining 40 or so?

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

post-production

read,

the sort of caps involved, not this company necessarily

for

definitely

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with

long

assume

I forgot about the mixer part, 103 of these same caps in the whole amp. So 2 failed in 3 years, where's a statistician when you need one ?

Fuck that. I'd hit it with the solder sucker & redo it with real solder.

that

crack

pin

guesses

Now a criminal act in Europe. The sign of the devil is not 666, it is the green label on this image

Who cares?

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definitely

with

with

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assume

I've not fully found out why MLCCs fail due to the extra heat of PbF. Its to do with thermal mass of the ceramic , but failure would seem to be cracking rather than going ohmic. Or does the cracking allow adjascent metalisations to bridge or approach very close. These were wire ended not SM, and failed by going progressively ohmic, the one that burnt out did not blow 1.6 amp fuses with 40 volt over it, the other one was down to 20 to 30K ohmic causing problem.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

This seems to explain the mechanism

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on