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October 2004

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Subject:
From:
"Ingemar Hernefjord (KC/EMW)" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Ingemar Hernefjord (KC/EMW)
Date:
Wed, 27 Oct 2004 09:11:49 +0200
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To those who gave me a hand: thanks a lot!
Special salute for John Maxwell.
Great assistance, I'd say!
Thanks, Steve, for hanging my pics.
Instead of endless trenchdigging, you can
just call TN. And you get help for nothing.
Unique society, hope all appreciate that.

The sum of our worry can't be adressed too openly,
but I can at least tell interested that even very
reputated cap manufacturers can mass produce capacitors
for some periods without knowing themselves, that the
caps have microcracks. Not until we tell them.
Incoming inspection is still necessary , as it seems...


Ingemar Hernefjord
Ericsson Microwave Systems


-----Original Message-----
From: Ingemar Hernefjord (KC/EMW)
Sent: den 26 oktober 2004 09:09
To: 'TechNet E-Mail Forum'; 'John Maxwell'
Subject: RE: [TN] Tombstoning


John Maxwell himself!

John, I have a concern, not about tombstoning, but chips as well. 6,8 nF NPO MLCC with TiO2,Nd2O3, Gd2O3. Notice, that there is no BaTiO3. Inner electrodes AgPd, terminations Ag/Ni/Sn. We get some percentage with internal microcracs, just after solder mounting operation.
Ordinary 60Sn, following std temp chart. We solder millions of cap chips without problem. But they are typically on less pF level. And made by other manufacturer...and contain Ba...

Had correspondence with you years ago, similar matter. We don't get ABD or TRA, but lowering internal series resistance which affects, of course, the RF filter circuitry in which these creeps work. From GOhm to KOhm, steady or fluctuating, even disappearing 'bridging'  and resulting in normal GOhm for hours or days, when suddenly back to annoying kOhm. Applied voltage far below maximum.

Examination showed internal microcracks, which I prompted to be extrinsic flaws and internal microcracs that lead to silver atom bridging with resulting lower insulation between nearby layers, but the cap manufacturer means that the cracks is the result of an inadequate soldering. There are also longer cracks, of an origin and character that are indeterminable from my viewpoint.

As you are extremly familiar with these questions, you may perhaps give your opinion after having a quick glance in Steve's gallery? I'll ask with best cordiality, if said Steve can put a couple of pics on the wall for your observation. Alternatively, we could chat offline, but there may be some more people with similar experience.

Thanks in advance.

Ingemar Hernefjord
Ericsson Microwave Systems

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