Yep ; Jim is pretty much on the spot .
Gaby the story goes :
Because the latest cap joints reliability studies did prove validity of VERY
much reduced pads;
those filter down as the recommended pad geometry's from manufacturers
(often contravening slightly out of date current standards) .
With that much reduced joint volumes you have a very high chance of getting
the gold level over the relatively recognized limit of 4% ; as the component
combines with dissolution from pad as well (even if smaller)if you have NiAu
boards.
I would metalograph it all prior to use .
Went actually that far as issued a memo stating no gilded component without
full joint analysis enter the floor .

On top you have a double trouble here , ceramic(size matters here) on FR4
with very much disagreeing CTE's and high gold embrittlement risk. Follow
manufacturers pads ; I'd bet they differ to your design fellow library .
Learned this the hard way ; watch the LED's too .

OR forget all i said and go with Jim's (if you have the choice)




Paul Klasek
ResMed



-----Original Message-----
From: Jim Bergenthal/MKT/HQ/KEMET/US [mailto:[log in to unmask]]
Sent: Wednesday, 13 October 1999 3:33
To: [log in to unmask]
Subject: Re: [TN] Soldering gold terminations


Suggest you procure standard smd capacitors with 100 % tin terminations.

If you are trying to use inventory that was procured for another reason,
you will probably have problems in soldering them.  I don't know how much
gold is plated on the terminations, but there is always concern for weak
gold tin intermetallics.






Bogdan Gabi <[log in to unmask]>@IPC.ORG> on 10/12/99 11:54:06 AM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
      to Bogdan Gabi <[log in to unmask]>

Sent by:  TechNet <[log in to unmask]>


To:   [log in to unmask]
cc:
Subject:  [TN] Soldering gold terminations


Dear Technetters!
Could you please give me information about the best soldering method and
materials for a ceramic capacitor with gold terminations on FR4?
Thanks,
Gaby

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