[SI-LIST] Re: What is the acceptable minimum pre-pregthickness for volume manufacturing?
- From: "George Dudnikov" <George.Dudnikov@xxxxxxxxxxxxxxx>
- To: "Chris Cheng" <Chris.Cheng@xxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Thu, 7 Sep 2006 17:23:58 -0700
Chris
ZBC materials are made with specifications for copper foil surface
treatments which reduce/control the surface RMS of the facing planes
thus reducing the probability of dielectric breakdown when the spacing
gets thin.. Before a material gets certified, it goes through a battery
of tests to insure reliability and integrity. The hypot requirement is a
verification that certain compliance standards are met and is required
to be performed to certain prescribed parameters multiple times in the
board fab process. Same applies to the Faradflex and Interra products
which have higher breakdown voltage ratings because there is no glass
cloth.
Concerns with single ply dielectrics apply more to power/ground layers
because of the large areas of opposing copper along with the difference
in potential of the planes. Single ply for signal layers is actually
quite common and has much less reliability risk.
Regards
George
-----Original Message-----
From: Chris Cheng [mailto:Chris.Cheng@xxxxxxxxxxxx]
Sent: Thursday, September 07, 2006 3:27 PM
To: George Dudnikov; si-list@xxxxxxxxxxxxx
Subject: RE: [SI-LIST] Re: What is the acceptable minimum
pre-pregthickness for volume manufacturing?
George,
Welcome to the Si-list.
I am always curious about this single ply reliablity in PCB.
Does the main benefit of ZBC on single ply reliability came from the
material itself or is it the extra hypot test to ensure reliability ?
The PCB material guys insist on double ply everywhere but when it comes
to thin core, it is ok to single ply all the sudden.
>As was previously mentioned on this thread, single ply dielectrics can
>be risky business when you think about voltage differential and the
>potentially catastrophic effect of any type of inclusion or conductive
>path between planes. Prepreg dielectrics have exposure to foreign
>material and inclusions during the glass yarn manufacturing, prepreg
>coating and PCB lamination processes. There is a significantly elevated
>risk of yield loss due to hard power ground shorts or field issues due
>to latent P/G shorting from electromigration.
>One of the benefits of licensed ZBC materials, in addition to certain
>structural specifications, is the requirement to hypot test the cores
>and finished PCBs to a minimum of 500VDC breakdown voltage using
>prescribed ramp rates and dwells. Film based dielectrics have the
>advantage of eliminating the glass weave and have even better voltage
>breakdown performance.
________________________________________________________________________
_____
Scanned by Sanmina-SCI eShield
________________________________________________________________________
_____
CONFIDENTIALITY
This e-mail message and any attachments thereto, is intended only for use by
the addressee(s) named herein and may contain legally privileged and/or
confidential information. If you are not the intended recipient of this e-mail
message, you are hereby notified that any dissemination, distribution or
copying of this e-mail message, and any attachments thereto, is strictly
prohibited. If you have received this e-mail message in error, please
immediately notify the sender and permanently delete the original and any
copies of this email and any prints thereof.
ABSENT AN EXPRESS STATEMENT TO THE CONTRARY HEREINABOVE, THIS E-MAIL IS NOT
INTENDED AS A SUBSTITUTE FOR A WRITING. Notwithstanding the Uniform Electronic
Transactions Act or the applicability of any other law of similar substance and
effect, absent an express statement to the contrary hereinabove, this e-mail
message its contents, and any attachments hereto are not intended to represent
an offer or acceptance to enter into a contract and are not otherwise intended
to bind the sender, Sanmina-SCI Corporation (or any of its subsidiaries), or
any other person or entity.
_____________________________________________________________________________
Scanned by Sanmina-SCI eShield
_____________________________________________________________________________
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
