Hey Jack ; I went through this battle of "seems" and "feels" and
"recommends" decades ago ;
and have had to validate it all on life cycling ; incl. carbon prints .
The carbon being add process and not so reliable as gold will cost you in
more ways than one .
Just get burned in small runs, if you insist .
Agree with your 5u" assessment ; check : (you have some 40u" in 1um) :
http://www.itri.co.uk/index.htm
Wear was not issue even on telephones ; up to 1M cycles , (as in
resistivities correlations) ; not on carbon pills on silicon mats .
The mat should be designed to stop your Pepsi .
On the pads we discovered interesting points : if you keep them close (like
four quadrants ; or two half moons); round up the sharp corners ;on plating
they've had tendencies to grow hairline bridges .
Those interspiraled or interfingered designs did not have enough pad area to
be bulletproof in VERY (1M+) long runs .
paul
PS
keep the u's clear : u" or um ; they grossly differ .
> ----------
> From: Jack Olson[SMTP:[log in to unmask]]
> Sent: Thursday, 18 March 1999 9:17
> To: [log in to unmask]
> Subject: Re: [TN] Flash Gold and Switch Contacts
>
> Ha!
> my past comes back to haunt me....
>
> Well, I have been TOLD by my SUPERIORS to plate 30u over 100u nickel, and
> I
> am telling them that that's too much gold for the SMT, but of course since
> I'm "the new guy" here they need to hear it from "a reliable source"
> too...
> (and 5u seems a little thin for contacts, I'll check into the carbon,
> never
> tried that)
>
> thanks everyone for the responses, I'm collating and summarizing
> onward thru the fog,
> Jack
>
> -----Original Message-----
> From: David J. Ricketts [mailto:[log in to unmask]]
> Sent: Wednesday, March 17, 1999 3:02 PM
> To: 'Jack Olson'
> Subject: RE: [TN] Flash Gold and Switch Contacts
>
> Jack, Jack, Jack, Jack,
>
> All that time at the company formerly known as B/E, and
> you
> still have gold
> questions?
>
> If the switch area is a contact surface, like a push
> button,
> then consider
> screening carbon ink. Otherwise, you can flash nickel and
> gold, 100 and 5
> microinches max.
>
> If it is a wear surface, like fingers wiping on the
> surface,
> then you need
> electrolytic gold.
>
> So what kind of grass do they grow in that new valley of
> yours?
>
> David
>
> MMI Designs
> voice> 949-675-7360
> fax> 949-673-3650
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Jack
> Olson
> Sent: Wednesday, March 17, 1999 9:58 AM
> To: [log in to unmask]
> Subject: [TN] Flash Gold and Switch Contacts
>
>
> I have just read through about a thousand messages
> regarding
> gold plating in
> the Technet archive, but still couldn't find exactly what
> I
> need to know:
>
> We have a design with one side all contact switch
> patterns,
> and the other
> side SMT components. Since we wanted to gold plate the
> contact patterns, we
> were told to just gold plate the whole board.
>
> So the question is: What gold thickness would be thin
> enough for the SMT's
> and still thick enough for good reliable contacts? Or is
> there a better
> way?
>
> thanks in advance,
> Jack
>
>
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