At IBM we use a proprietary electrical tester for some of this work for opens.
TDR might work if you know the layer/net length. Xray will work only on boards
with 4 layers or less typically, beyond that it gets hard to see with all the
overlapping circuits. Shorts of course show up as burns if you give 'em enough
juice and short one net to ground, but then, there isn't much left when you are
done for FA. Because we know net points and can tie them to specific layers of
the board, so long as we get within a few inches, a z-section will usually find
the short.
Most of our non-critical work for shorts simply involves looking up the
shorted nets on a data system and finding where the nets are close. We cut out
that piece of board, and work it down with typically a z-section to the layer
involved for Failure Analysis work. For non-critical work on opens, we usually
have enough wiring vias that you can meter the net looking for the open, and
again, once you are within a few inches, a z=section will usually show it to
you.
you didn't indicate that you wanted to save the parts, so I assumed that you
wanted them for Failure Analysis. If you don't have the net layouts on a CAD
type system to be able to call them up by their endpoints, well, then things
get a lot harder.
Jim Herard
KBL, Product Quality Engineering
IBM Microelectronics Endicott
t/l 857-7026
[log in to unmask] on 01-22-98 09:12:38 AM
Please respond to [log in to unmask] @ internet
To: [log in to unmask] @ internet
cc:
Subject: [TN] Finding shorts & opens inside PWB's
Hi People,
Does anyone have precise methods of isolating locations of shorts and opens
inside a finished PWB. Electrical Test, Probots and Micro-Ohmmeters hint at the
areas of the defects, but dont reveal the actual location. I am wondering if
anyone has tried Infared Thermal Imaging, High Resolution x-ray or Tracing high
frequency signals through a board. New project and little frustrated, Thanks
for any help.
Dave Kleinman
Optical Inspection Engineer
Raytheon-TI Austin, TX
512-250-7141
##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text
in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe:
SIGNOFF TECHNET ##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information. For the technical support contact Dmitriy Sklyar at [log in to unmask]
or 847-509-9700 ext.311
##############################################################
##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe: SUBSCRIBE TECHNET <your full name>
To unsubscribe: SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information.
For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311
##############################################################
|
