[sebhc] [Fwd: ANSWER: General Comments from Mouser website.]

[Dwight K. Elvey]

>From: "Scott LaBombard" <labomb at rochester.rr.com>
>
>Folks,
>
>A quick glance at http://www.molex.com/product/pcb/4455t.html shows that
>there are a couple of alternatives for this part. If you want to forgo
>'select gold'
>and instead go for the plain old 'gold' contact part, then your part number
>would be 22-18-2253.
>
>The folks at http://www.arrow.com/aws/pg_welcome have this part in stock.
>In addition, they sell to individuals and have no minimum order requirement.
>They show a price of $4.27 per unit.
>
>There's also a tin contact variation as a last resort ...
>
>
>Scott
>

Hi
 As I noted, you should only use gold if the mother board also
has gold pins. Never mix metals on pin contacts. Contacts go
bad fast enough as it is without adding electrolysis.
 For those that worry about contact and want to protect their
older machine, placing some Dow-Corning #4 silicon grease on
the pins will improve contact and protect them from normal
electrolysis. There are issues in a salt air environment
but I've not had any problems and I live within 2 miles of
the coast. The grease has no other electrical problems and
is itself, non-conductive. I use it on, switch connacts, TV
tuners, EPROM pins, card edge connectors, lamp sockets, power
connectors, screws that hold regulators or power transistors
and just about anywhere that one has metal to metal that
has to carry current. I have a HiFi amplifier that has a
toroidal transformer. This used to cause the power switch
to arc and stick together ( I suspect the core was saturating
on the first cycle ). I put the grease in the switch and
it has been working fine for over 10 years now. When I
worked at Intel, we did some studies on card edge connectors.
The normal gold on gold contact had about 10 to 15 milli-ohms
of resistance. With the grease, this dropped to under 2 milli-ohms.
This was true even after the environmental chamber at 90%
humidity where the normal gold on gold would degrade to around
30 to 50 milli-ohms. They chose not to use it there because
once it got on a surface, one could not get lettering stamps to
work. This isn't an issue for us because we rarely add such
to our machines.
Dwight


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