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February 1999

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Subject:
From:
Brett Goldstein <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 26 Feb 1999 09:10:05 -0000
Content-Type:
text/plain
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text/plain (48 lines)
Greg,
        I've seen this type of thing happen, where a silver filled die
attach adhesive (probably through silver migration) shorted to
traces below the die.  We mostly make ceramic hybrids, so our
solution was to use a couple of layers of glass encapsulant
(designed for encapsulating fired resistors, and not containing any
pin holes) as a die pad.  The glass encapsulant does have to be
fired at a high temperature (800 C or so), so it is only a solution for
ceramic substrates.

Brett Goldstein
EVI, Inc.


> Hi Designers,
>
>         I'm in need of help!  I have completed a design with some L157
>         IC's
> on the Board. And Manufacturing came back to me after I finished the
> design and was about to ship it and said that they use a conductive epoxy
> to adhere the die to the Board and they're worried that if the Solder
> Resist has pin holes in it that it could leak a signal into the runners
> below those Die.  They said they could use Pre-Forms but that would kill
> their yeild so they want me to reroute the traces below those die.
> Unfortuatley that would be a nightmare and add at least a week to my time.
>  So can anyone tell me where I can get info to help prove that this won't
> be a problem or are they right and there's a good possiblitiy that this
> could happen.
>
> Thank you,
>
> Greg Bodi
>
> [log in to unmask]
>

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