Subject: | |
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Reply To: | (Combined Forum of D-33a and 7-31a Subcommittees) |
Date: | Mon, 9 Nov 2009 12:56:10 -0600 |
Content-Type: | text/plain |
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But what do you do when you find eyebrow cracks? Brow-beat the supplier?
Fritz
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Whittaker,
Dewey (EHCOE)
Sent: Monday, November 09, 2009 12:50 PM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Double-Blind Via Construction and IPC-6012C
A good discussion; maybe: raise a few eyebrows; certainly.
Dewey
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Denise
Chevalier
Sent: Monday, November 09, 2009 11:39 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Double-Blind Via Construction and IPC-6012C
More photos for thought - agree this will be a good discussion.
Typically see these defects in thin dielectric area.
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Lance A
Auer
Sent: Monday, November 09, 2009 11:59 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Double-Blind Via Construction and IPC-6012C
John,
This will be a good discussion, but it may interfere with your
schedule for release of the next revision or 6012. We certainly have
seen small cracks between the pads in dual-bllind constructions. They
are
termed "eyebrow" cracks since they appear above the pads on the blind
holes. As long as they are small and located adjacent to the pads, we
have considered them to be "in the thermal zone" and acceptable. It
would
be a good step forward to identify this structure and define actual
accept/reject criteria.
Thanks,
Lance
John Perry <[log in to unmask]>
Sent by: IPC-600-6012 <[log in to unmask]>
11/09/2009 09:07 AM
Please respond to
"(Combined Forum of D-33a and 7-31a Subcommittees)"
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To
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Subject
[IPC-600-6012] Double-Blind Via Construction and IPC-6012C
Hello Everyone,
Recently, we updated the attached IPC-6012C Figure 3-9 to better
illustrate requirements for laminate anomalies in Zone A and Zone B.
A question has come up regarding laminate anomalies in double-blind via
constructions. Please refer to the attached PowerPoint file. The
questions are:
* Are laminate defects in Zone A allowed after thermal stress?
* Are any defects allowed in the non-thermal stressed condition
in
Zone A?
* What would be the size of defects allowed? Would they be the
same as for standard PTHs?
* If defects allowed in non-stressed condition is there a
minimum
spacing requirement of resin/glass between layers?
Let's discuss this through this IPC-600-6012 e-mail forum and see if
there
is a need to further update IPC-6012C Figure 3-9 (or duplicate it and
modify as needed for double-blind constructions).
Regards,
John Perry
Technical Project Manager
IPC - Association Connecting Electronics Industries(r)
3000 Lakeside Drive # 309S
Bannockburn, IL 60015-1249 USA
+1 847-597-2818 (tel)
+1 847-615-7105 (fax)
+1 847-615-7100 (Main)
[log in to unmask]
www.ipc.org
[attachment "6012c-3-9.jpg" deleted by Lance A Auer/US/Raytheon]
[attachment "Blind Via Defects 11-08-09.ppt" deleted by Lance A
Auer/US/Raytheon]
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