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August 2009

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Subject:
From:
Steven Creswick <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Steven Creswick <[log in to unmask]>
Date:
Wed, 5 Aug 2009 11:50:01 -0400
Content-Type:
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text/plain (144 lines)
Victor,

Double check TM 2010, it has a little more die attach detail.  

I was suggesting the FC section thinking the back-side the device being like
a FC - basically non-functional bulk. - That would not be a good analogy for
your application.

When you say "power", the fur on the back of my neck immediately goes up and
I get really scared when you even hint at the word 'crack' near the attach
surface.

I have power cycled devices before and had the top of the chip crack
entirely through - leaving the entire base of the device attached to the
substrate.  I can not imagine having done this with a device that may have
been cracked in the first place.

I vote that you play it entirely safe if there are cracks.  Scallops could
be a bit safer, but still would like to know where they are coming from to
make me sleep better in the evenings.

Steve C



-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]] 
Sent: Wednesday, August 05, 2009 11:36 AM
To: [log in to unmask]; [log in to unmask]
Subject: RE: [TN] die base chip outs / fractures

Steve,

   Thank you for sharing.   The current revision is G and I have B.   I
reviewed the current TM 2017 and I didn't see much as far anomalies,
cracks/fractures of the bulk silicon at the bonding area.   The device
is a power diode package, 2x, per package, To266.  It is not a flip chip
application.

Victor,

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
Sent: Wednesday, August 05, 2009 8:20 AM
To: [log in to unmask]
Subject: Re: [TN] die base chip outs / fractures

Victor,

I am not sure what the IPC equivalent to MIL-STD-883 would be, but if
you
refer to 883, TM 2010 - internal visual - monolithic, or TM 2017
internal
visual - hybrid you may find what you are looking for.

My recollection is that TM 2010 may provide the most info [para 3.1.3]
although we were mostly concerned about chip-outs at the upper edge of
the
chip, nearer to the active region.  You might consider the section on
flip
chips for info as well.

If the chips are diced with a diamond saw, one seldom [if ever] sees
chipping along the bottom edge of the die unless there has been
mis-handling
of the sawn wafer while still on the frame.  Mainly, don't want cracks
going
in the direction of the active region of the chip - [personally, don't
want
to see cracks AT ALL - especially, if you can see them with a low-power
scope, etc].

We would not want to see loose bits of Si rattling around inside a
sealed
hybrid.  If over-molded, it is not so likely to move anywhere...

Interested in further detail of the chipping you are seeing.

You should be able to down-load MIL-STD-883G from
http://assist.daps.dla.mil/online/start/
Once you get the user sign-on info.  It is a ~6 Mb file

Steve


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
Sent: Wednesday, August 05, 2009 8:16 AM
To: [log in to unmask]
Subject: [TN] die base chip outs / fractures

Fellow TechNetters:

   Is there an IPC documents pertaining to acceptance of anomalies with
die.   I am see small cracks/chip out at the die to die attach region.
How much chip out/ crack is allowed?

Victor,

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