Dave,
     We have had some luck locating high resistance under flip chip using
     thermal imaging, but could not use the technique to find hard opens.
     We also put some effort into time domain reflectometry to locate opens
     with little success, but the technique could possibly work with
     further refinement.
     Rod Martens
     Hewlett-Packard Co.
     Fort Collins, CO


______________________________ Reply Separator _________________________________
Subject: [TN] Finding shorts & opens inside PWB's
Author:  Non-HP-dkleinman ([log in to unmask]) at HP-ColSprings,mimegw4
Date:    1/22/98 2:54 PM


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

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