At 09:03 AM 4/7/00 -0500, you wrote:

>I had a couple of questions concerning the prevention of fretting corrosion.  I am in the
>process of reviewing and updating some of our older process procedures.  At present the
>procedure on Lubrication of Connectors is setting in front of me and I have managed to
>raise a few questions.  A search of the Technet archives and some old memory banks have
>produced: gold to gold - its a good thing, no lubricant required: tin/lead to tin/lead -
>its a good thing if lubricated: gold to tin/lead - not good, even with lubrication.  I
>know some of the information on this subject is dated, but I don't believe the passing of
>time has invalidated it.


See Bellcore TR-NWT-001217 "Generic Requirments for Separable Electrical Connectors Used in Telecommunications Hardware" Section 5.3 and GR-78-CORE "Generic Requirements for the Physical Design and Manufacture of Telecommunications Products and Equipment" Section 4.1.4.

Both noble and base metal connector contacts are to be lubricated for telecommunications hardware, except noble metal contacts locked into place. I believe the auto industry is also specifying lubrication in many instances, as it can be shown to improve reliability.


>On products where we build the entire assembly, I can easily verify the total connector
>configuration.  However, when we are building only a circuit board assembly for a
>customer, I have no idea of materials used in the mating connectors.  To further
>complicate the issue, I know that some connector manufacturers lubricate the tin or
>tin/lead female connectors and some manufacturers do not, or at least won't verify that
>they do.

Just ask whether the connector meets TR-NWT-1217 requirements - this covers a lot more ground than lubrication, though. If it does, then it has been lubricated. Generally, only one of the mated connector pair must be lubricated per the Bellcore requirements.

>Is there an industrial specification/requirement for the lubrication of connectors on
>circuit board assemblies that should be called out in the product specification?


see above

>At present we are using a contact lubricant on all tin or tin/lead plated male connector
>contacts, except when the mating connector is known to be prelubricated.  The lubricant we
>are using must be allowed to cure out 24 hours prior to assembly.  This is not real
>conducive to lowering cycle times.  Is anyone aware of a contact lubricate the would
>improve on this?


Why do you say "must"? The best lubricant is Monsanto OS-138 six ring polyphenyl ether, which is incredibly stable. It has a consistency like molasses at RT. 24 hours of aging would not affect this material.

The time factor you describe may relate to the evaporation of the solvent used as a carrier. Typically, this material would be diluted 2% in a solvent like naptha (highly flammable) or a perfluorinated solvent (highly restricted/expensive); then either dipped or sprayed to apply.

We have one customer who is contractually obligated to meet the GR-78 requirement on an end product using one of our board assemblies, so we lubricate the pin and socket I/O connectors, the IC sockets, etc. prior to shipment.

We presently use 2% OS-138 dissolved in Allied Signal  "Genesolv 2000" (dichlorofluoroethane) applied with an artist's airbrush. Works like a hose, and the carrier dissolved in seconds.

You could also call Nye Synthetic Lubricants, they supply a variety of prepared connector lubricant solutions.
See:

http://www.asknye.com/automotive/connectors.html
http://www.nyelubricants.com/


regards,

Jerry Cupples
Interphase Corporation
Dallas, TX USA

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