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September 2004

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From:
"Nowland, Russell Howard (Russell)" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Nowland, Russell Howard (Russell)
Date:
Mon, 13 Sep 2004 08:07:01 -0500
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Carrie,

I agree will all the comments.  I am assuming this are through-vias.  I would just like to add, you have to be somewhat lucky to nail a void in a cross-section. It just takes one grind to many or one not enough to miss it.  One thing to look for is drill quality.  Look at the walls of the drill and plating and if they are rough then there is a potential for plating or voids within the plating.  This is caused by to many hits on a bit, the wrong drill speed, etc...



Russell Nowland
Lucent Technologies
Quail Springs Parkway Plaza
14000 Quail Springs Parkway. Suite 300
Oklahoma City, OK 73134
Phone: 405-302-1660
Fax: 405-302-1622
Cell: 405-203-0034
email: [log in to unmask]


-----Original Message-----
From: Lee Parker [mailto:[log in to unmask]]
Sent: Friday, September 10, 2004 2:31 PM
To: [log in to unmask]
Subject: Re: [TN] Blow Holes -- Where the heck does the moisture come
from anyway?


Carrie

If you cross section the vias, remove the solder from the hole and look
at the copper barrels at very high magnification (use and SEM if
possible)you may see pin holes in the copper or glass bundles protruding
into the hole. This coupled with moisture in the dielectric which is
normal can create the mechanism. When the board is quickly heated in
assembly (reflow or wave solder) the moisture is pressurized and flows
out through the pin holes into the barrels blowing the molten solder in
the barrels out onto the board.

Best regards

Lee

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Morse, Carrie
Sent: Friday, September 10, 2004 2:33 PM
To: [log in to unmask]
Subject: [TN] Blow Holes -- Where the heck does the moisture come from
anyway?

Just wondering a few things here at 2:30 on Friday Afternoon:

1.  What else causes Blow Holes at wave on TH comps?  Is it primarily
moisture?
2.  Where does the moisture come from?
3.  Are certain board materials more likely to sponge up the moisture in
the air?
4.  Can hole wall quality play a part in contributing to blow holes?

-Carrie

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