Andrew.
Are you involved with developing flight boards?   From time to time I will
do a flight design for NASA/GSFC in Md.  GSFC has a spec S-312, that
prohibits anything except  tin/lead hasl finish for flight boards. Gold /
white tin, etc are strictly prohibited .   When we spec a board out tin/
lead is the only choice.   I am not sure about the chemical /molecular
interaction between gold and tin but, I know they don't like gold plated
boards for flight.   There is apparently  migration from the gold to the
tin, and somehow this translates into reduced reliability ( can anyone
elaborate on this?)   I'm not even sure if this a specific problem to the
environment in space or just an interaction between gold and solder.   For
that reason, we don't use gold or white tin plating.

Interestingly, many component leads will be gold plated on flight approved
hardware.  Go figure that one out


Mike Reagan
EDSI



----- Original Message -----
From: Andrew J Jenkins <[EMAIL PROTECTED]>
To: Protel EDA Forum <[EMAIL PROTECTED]>
Sent: Tuesday, April 17, 2001 3:29 PM
Subject: Re: [PEDA] Gold Emersion


> On 01:17 PM 4/17/01 -0400, [EMAIL PROTECTED] said:
> >Can anyone direct me to some research papers published about the
advantages
> >and disadvantages of using Gold emersion on mulitlayer pcbs. I have only
> >heard information from pcb vendors but would like to see something
> >published. Any documentation that includes manufacturing results would be
> >great.
>
>
> Have you checked PCB and SMT magazines? I believe that both have published
> articles on plating in the past, and they might offer a bit more objective
> treatment than what might be expected from the PCB houses. EDN might also
> have something to offer, as they have treated PCB mfg-ing in the past
> (though I can't remember how recently...)
>
> Also, try
> regards,
>
>
>
>
> 2.2   S E C O N D   D R O P   T O W E R
> Andrew J Jenkins        Electrical Engineer
> National Center for Microgravity Research
> NASA-Glenn Research Center MS 45-1
> 21000 Brookpark Rd, Cleveland OH 44135
> (216) 433-5001 fax:433-3793
> [EMAIL PROTECTED]
>
>


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