TECHNET Archives

April 2008

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Ryan Grant <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Tue, 22 Apr 2008 16:08:33 -0600
Content-Type:
text/plain
Parts/Attachments:
text/plain (116 lines)
Steve,

I would much appreciate your help with posting these pictures.

Thanks,
Ryan

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Franklin D Asbell
Sent: Tuesday, April 22, 2008 3:55 PM
To: [log in to unmask]
Subject: Re: [TN] Via barrel cracks

Would you have an image for posting?


===================
Hi Technetters,

I have a case of via barrel cracks (E crack) and I would like to know
possible causes.  

The crack is circumferential and occurs at the center of the via.  The
hole appears smooth, i.e., no glass nodules or tearout and there is
neither positive nor negative etchback.  Of course there is some
wicking, but only about 25um max.  The copper thickness is 20um at the
crack and roughly 35-40um at the knee.  Although, at the initiation
point of the crack, the copper thickness is only 10um, but that could be
due to stretching and subsequent thinning of the copper.  Around the
periphery of the crack are micro-voids in the resin about 30um.  It is
triangular shaped, so I can't tell if it is resin recession or a
laminate crack.  

In other words, this via pretty much looks normal, except for one thing,
which might be an artifact of stretching and cracking of the via.  For a
span of about 60um on the vertical of the via, at the crack, there is a
roughness that slightly reduces the copper thickness.  The surface of
the copper at this point appears both rough and black in color.

This board has seen two reflows and a hot functional test before final
failure.

The board shop's initial response was speculation of the OSP soft etch
attacking the copper, but this particular via has solder mask plugging
both sides of the via; therefore chemicals after solder mask cure can
not get into the via.

In case it matters, at one time, we have had occurrences of this board
shop "re-working" panels after copper plating by placing the panel in a
tank of etchant, then re-running the board through copper plating.
(They do panel plating).

I'm a little suspicious of their FA, so I would like some independent
opinions and places for me to dig into.

Thanks for any help,
Ryan

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 To
unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
(re-start) delivery of Technet send e-mail to [log in to unmask]: SET
Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the
posts: send e-mail to [log in to unmask]: SET Technet Digest Search the
archives of previous posts at: http://listserv.ipc.org/archives Please
visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for
additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text
in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16
for additional information, or contact Keach Sasamori at [log in to unmask]
or
847-615-7100 ext.2815
-----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text
in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------

ATOM RSS1 RSS2