Daan,

There are many questions that need answered to arrive at a reasonable
answer.

1. Are there dissimilar metals involved between the PLCC and the socket
contacts?
     If so then fretting is definitely occurring.
     If not then airborne contaminants are collecting in the contact area.
     The difference is how soon are these "intermittent"  problems show up
     ( dissimilar metal fretting occurs sooner in most cases).

The use of "lubricants" creates a new set of issues that must be addressed.

2. What are the environmental conditions that the hardware is exposed to
and is the
    "lubricant" qualified to work in those conditions?

3. How long will the "lubricant" be able to perform its function?
(nothing lasts forever)
    These "lubricants" work by "floating/suspending" materials away from
the contact surfaces.
     They are generally very large/heavy organic molecules. Every brand
as a different molecular
    structure. Even within the same brand they will change these
formulas when the manufacturers
    think they can make improvements.

4. How long will it take for the lubricant to become "saturated"and/or
begins to break down reacting
    with contaminants (reactive gases, moisture, acids, etc...)?

5. What effect will this lubricant have on circuitry operation, (effects
will change as more and more
    contaminants collect in the lubricant) such as dielectric constant,
leakage currents, cross talk, ect...?

6. Does the lubricant "attack" or cause long term degradation of the
hardware
    (plastics can react with organic compounds)?

7. How is the lubricant removed/cleaned up after it has reached its life
limit and will the chemicals
    needed degrade the hardware?

These are some but not all of the questions needing answers.

Good luck and I hope this helps.

David A. Douthit
Manager
LoCan LLC




Daan Terstegge wrote:

>Good morning Technet,
>
>One of our products was returned to us due to a bad contact between the
>leads of a PLCC and the socket in which it is placed. Somebody here got
>the idea that the contact failure might be a result of fretting
>corrosion, and that using an anti-fretting lubricant may be the solution
>for it. At a previous employer we used such a lubricant for some
>connectors, but I have never heard of lubricating the contacts of a PLCC
>socket.
>Any opinions on this ?
>And what else can cause contacting problems in a PLCC socket after some
>time ?
>
>Best regards,
>
>Daan Terstegge
>Thales Communications
>Unclassified mail
>Personal Website: http://www.smtinfo.net
>
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