In comp.sys.ibm.pc.hardware.storage Sergey Kubushyn wrote:
In sci.electronics.repair Arno wrote:
[...]
Those 4 were fine on the top of PCB. Black stuff was underneath, on those
pads contacting with springy heads pins.

Mine is fine on both sides. However there is a quite a bit of contact
area that looks and feels silver-plated to me, most notably areound
the screws and on the bottom the contacts to the head assembly.

That makes me wonder why are they silver-plated. It is definitely
not the best material longevitywise, especially for such low-level
signals. It makes me even more suspicious and adds to the conspiracy
theory.

Well, maybe. However I tend to think that "never attribute to
malice what can be adequately explained by stupidity" may apply.

These contacts should be gold plated with high quality gold. It is
also possible that the HDD vibration (always present with a running
HDD) and thermal variation allows the process to creep between the
contacts and kill them. Maybe a young, inexperienced engineer was
hired to replace an older, experienced (but more expensive one)
and that person made a pretty bad judgement call due to
inexperience, wanting to save a few cents on the design.

I have to say that the last time I saw silver plating as contact
protection was in vaccuum tube equipment. Modern electronics
typically uses Gold, or Tin for low insertion cycle contacts.

I also found a statement on Wikipaedia that silver plated
copper, once the copper is exposed in a place, will rapidly
corrode all over because of some electro-chemical process.
No idea whether this is true or not.

Arno
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Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email:
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Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans