Browse Prior Art Database

Circuit-Board Leakage Detection Methods

IP.com Disclosure Number: IPCOM000105523D
Original Publication Date: 1993-Aug-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

DiStefano, TH: AUTHOR [+2]

Abstract

Potential short circuit locations on printed circuit boards can be detected by using AC low voltage at a fundamental frequency and probing for harmonics of that fundamental frequency.

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Circuit-Board Leakage Detection Methods

      Potential short circuit locations on printed circuit boards can
be detected by using AC low voltage at a fundamental frequency and
probing for harmonics of that fundamental frequency.

      The method comprises applying a pure AC excitation voltage at a
fundamental frequency (fo) to a ground plane or a power plane that
extends throughout one layer of the board.  Each of the other
conductors in the board exhibits the same AC voltage applied to the
plane because of capacitive coupling.  As each signal line is probed,
in turn by the low impedance detector, the voltage in the selected
line droops to nearly zero.  Wherefore, current will then flow
between that conductor and any other.  If the leakage is non-linear
because of electrolytic activity (or because of local heating from a
narrowed conductor path), the detected current will contain
harmonics (2f sub o,  3f sub o) of the fundamental voltage.
Frequencies at these harmonics are an indication of the presence of
potential short circuits.  Thus, lon-linear leakage  impedances will
convert fo to 3f sub o and are able to be measured and distinguished
by the presence of the harmonics.