24 layer stack with cofired AuAg top. Lifts at ball bond pull tests,
insufficient adhesion, I would say. Should take 4,000 psi. Smashed ball
approx. 2 mil diameter. If the gold lifts at 10 grams, then you are >
one magnitude below 4,000 psi. SEM'd edges of lifted lines= 2
micrometers thick. Paste maker recommends >7 micrometers as fired.
Substrate maker denies, that's why I'm asking for method to check all
incoming parts without destruction of the gold.
Abcd recommended confocal laser, don't think that will work. VHF
transducer, not bad idea! Good. Will test that next week. Thanks.
Inge
-----Ursprungligt meddelande-----
Från: TechNet [mailto:[log in to unmask]] För Creswick, Steven
Skickat: den 29 mars 2007 16:14
Till: [log in to unmask]
Ämne: Re: [TN] Cofired gold
Ingemar,
Are you speaking of a standard, single print of gold which has been
co-fired into the body of the part, or possibly of a stack of inks which
has been co-fired in at one time?
XRF comes to mind, but it will require special 'standards', and the prep
of the standards would result in the destruction of a sample of parts to
construct them ... and even then I am not sure how successful you will
be.
It sounds as though a simple profilometer won't get you what you desire
- especially since the bulk of the conductor is below the surface. I
occasionally did internal inspection of LTCC parts back in the olden
days - but that was looking more for omissions and commissions.
I believe that acoustically, with a very high frequency transducer you
should be able to gate off the top and bottom surface of the conductor.
The margin of error [due to surface imperfections] may be quite large,
however.
Can you get them to tell you what their stencil thickness was and based
on solids content have some idea what you may have ended up with?
Will ponder further
Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Hernefjord Ingemar
Sent: Thursday, March 29, 2007 9:39 AM
To: [log in to unmask]
Subject: [TN] Cofired gold
Trikeman or other gnu,
Anyone know of a non destructive method to check cofired topgold
thickness (Au over LTCC)?
Inge
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