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'[EE] Fragile component leads'
2006\08\13@233818 by K S

picon face
Hello list.

A warning to all and also looking for feedback of similar past experiences.

I've been using ST L6203 H-bridges on many of my products over the last few
years. Thousands have gone out without a single issue, ever.

Just the other month I organised a kitting company to supply me the L6203s
as part of a kit. I assumed they *might* get them from the grey market but
that was immaterial to me. Then suddenly I started having many failures both
during testing and in the field. Failures approached 25%! Generally,
replacing the faulty L6203 with another solved the problem.

I was completely stumped until I noticed that while replacing the parts the
legs would easily snap off. Then comparing them with older parts obtained
from the authorised distributor I noticed that the legs had a much duller
and lacklustre finish, occasional jags (and also occasional whisker-like
protrusions) and were very brittle. It turns out that most of the failures
were due to almost invisible mico-cracks in the pins; if i applied solder to
the pins it would usually fix the problem. This created a nightmare during
debugging as I'd put the scope probe on the base of the lead not knowing
that it never reached the silicon inside.

I don't know whether this is because that batch of parts were RoHS compliant
(the dull finish may be due to that), the fab that made these (Singapore) is
a dud or whether they are frauds? I have been assured that the origin of the
parts was Future in the USA.

Regards, Kris.

2006\08\14@051537 by Bob Axtell

face picon face
K S wrote:
{Quote hidden}

This can happen when the devices are stored in an area in which the
devices are attacked by high heat
and an acidic atmosphere. Probably the metal was simply weakened by
attack. My guess is that they
were improperly stored.

--Bob

> I don't know whether this is because that batch of parts were RoHS compliant
> (the dull finish may be due to that), the fab that made these (Singapore) is
> a dud or whether they are frauds? I have been assured that the origin of the
> parts was Future in the USA.
>
> Regards, Kris.
>  

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