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March 2005

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Subject:
From:
Al Onderick <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Tue, 22 Mar 2005 09:47:03 -0600
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text/plain
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Our experience with soldermask tented vias indicated that it was not a
robust process. On occasion there is a pin-hole in the mask and liquid is
trapped in the hole and ejected during thermal excursions.







-Al Onderick

National Instruments



-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]] On Behalf Of
[log in to unmask]
Sent: Tuesday, March 22, 2005 7:35 AM
To: [log in to unmask]
Subject: Re: [TN] VIA Tenting Question



The IPC has a task group writing a document regarding Via Protection and I

personally think this is one of the most important topics needed to be
covered

by the group.  The task group is D33-d and you can download the latest
version

of the document, which is scheduled to be released this summer from the
IPC

website.



Recently we have performed numerous failure analysis on vias that have

partial plugging/tenting that have contaminates trapped within the  via
from both

the board fabrication and the assembly processes.  The hole walls are bare

copper and they did not survive the corrosion.



There are so many things to consider when choosing what to do for via

protection, but in my humble opinion if the barrels are left bare copper
only

complete plugs and tents have a chance of protecting the vias.  If you are
using ENIG

in the vias then you can concentrate on what is needed for your assembly

processes knowing the barrrels of the vias are protected from
contaminates.



Susan Mansilla

Robisan Lab



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