You're right Charles; 60 u" will put you over the edge on cycling ; half
would be prudent .
I do not know how did you arrive to "being killed" ; presume some cycling
regime ; to some designed life ;
however with J's on in theory I'd agree with Kelly you should have not that
much problems with embrittlement > on laminate ;
the 60 u" being just on the beginning of the brittle threshold ; leadless I
would understand ; but leaded you should not break that fast .

That would be on the assembly side onto the main card .

Than again reading it three times ; I think you talk about the gold on the
ceramic plate ;
than 60 u" is much likely over the top ;
Have a chat with Jeff ; he's got first hand experience exactly on the
(dreadful) subject of gold removal from ceramic hybrids ;
worked on pacemaker implantables for years in Telectronics ; supervised
fab.s & assy .
He moved to making musical instruments nowadays ; but on this particular
subject he's your man more than me .

Are you tied to this particular hitemp alloy ? ; the high silver content may
not be on your side as well ;
check suppliers ; like's indium .

See you

Paul Klasek
http://www.resmed.com

> ----------
> From:         <Charles Barker>[SMTP:[log in to unmask]]
> Sent:         Friday, 2 April 1999 8:25
> To:   [log in to unmask]
> Subject:      [TN] Gold embrittlement/Attaching Gold Plated leads to
> PWB's.
>
> I need to attach a J-leaded ASIC to one side of a ceramic board,
> up-side-down, and a custom leadless ceramic part on the opposite side.
> The spec for the leads of the ASIC package are: made out of Kovar or Alloy
> 42. All exposed metal and metallized area shall be gold plated with 60
> micro-inches gold (min) over nickel plating.
>
> We would like to attach this part using an solder alloy with a reflow temp
> somewhat above that of 63/37, but below 280 C (lid attach temp), so we
> won't unnecessarily reflow this part again when it is attached to it's
> main
> board.
>
> We have tried 96.5 Sn/3.5Ag (221 C eutectic) and are being killed with the
> gold embrittlement/poisoning.
>
> Any suggestions?
>
> TIA
> Charlie B.
> 281-552-3328 Voice
> 281-552-3100 FAX
> [log in to unmask]
>
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