Method and apparatus for determining the location of a short...

Details Method and apparatus for determining the location of a short... Method and apparatus for determining the location of a short...

2000-11-16

2003-11-18

Hoff, Marc S. (Department: 2857)

Data processing: measuring, calibrating, or testing

Measurement system in a specific environment

Electrical signal parameter measurement system

C702S057000, C702S058000, C702S064000, C702S065000, C702S069000, C702S183000

Reexamination Certificate

active

06651013

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a method and apparatus for locating an electrical short between two nets in an electrical wire network.
2. Related Art
Current technology is unable to accurately, efficiently, and nondestructively locate an electrical short between two nets in an electrical network of a microelectronic structure (e.g., a circuit board).
A method and apparatus is needed for accurately, efficiently, and nondestructively locating an electrical short between two nets in an electrical network of a microelectronic structure.
SUMMARY OF THE INVENTION
The present invention provides a method for locating a short between a first net and a second net, comprising the steps of:
providing the first net and the second net, wherein the second net is electrically shorted to the first net at an unknown point P
S
on the first net;
selecting points P
A
and P
B
on the first net such that P
S
is at a location on a path between P
A
and P
B
along the first net;
electrically connecting a constant current pulse source between P
A
and P
B
;
electrically connecting a first voltage measuring device between P
A
and P
B
;
selecting a point P
C
on the second net;
electrically connecting a second voltage measuring device between P
A
and P
C
;
activating the constant current pulse source to generate a constant current pulse at a time t=0, wherein the constant current pulse has a width &tgr; and a height I;
activating the first voltage measuring device at a time t
1
, wherein 0<t
1
<&tgr;, and wherein the first voltage measuring device records a voltage drop V
AB
from P
A
to P
B
;
activating the second voltage measuring device at a time t
2
, wherein 0<t
2
<&tgr;, and wherein the second voltage measuring device records a voltage drop V
AC
from P
A
to P
C
;
defining L
AS
as a length of the path from P
A
to P
S
; and
calculating L
AS
as a function of V
AC
/V
AB
.
The present invention provides an apparatus for locating a short between a first net and a second net, comprising:
the first net and the second net, wherein the second net is electrically shorted to the first net at an unknown point P
S
on the first;
points P
A
and P
B
on the first net such that P
S
is at a location on a path between P
A
and P
B
along the first net;
a constant current pulse source electrically connected to P
A
and P
B
, wherein the constant current pulse source is generating a constant current pulse having a pulse width &tgr; and pulse height I;
a first voltage measuring device electrically connected between P
A
and P
B
, wherein the first voltage measuring device is recording a voltage drop V
AB
from P
A
to P
B
; and
a second voltage measuring device electrically connected between P
A
and a point P
C
on the second net, wherein the second voltage measuring device is recording a voltage drop V
AC
from P
A
to P
C
; and
a calculation algorithm which computes L
AS
as a function of V
AC
/V
AB
, wherein L
AS
is a length of the path from P
A
to P
S
.
The present invention provides a computer method for locating a short between a first net and a second net such that the short is at a point P
S
at a location on a path between points P
A
and P
B
on the first net, comprising the steps of:
providing a computer system having:
a memory device;
a computer code located on the memory device, said computer code including a calculational algorithm which calculates a length L
AS
along the path from P
A
to P
S
;
a processor for executing the computer code; and
an output device;
providing input data for the computer code, including: a voltage drop V
AB
from P
A
to P
B
, a voltage drop V
AC
from P
A
to a point P
C
on the second net, and geometric data describing a spatial distribution of an electrical wire network which includes the first net;
executing the computer code, wherein the calculational algorithm computes a length L
AS
of the path from P
A
to P
S
as a function of V
AC
/V
AB
including utilizing the geometric data; and
displaying L
AS
by the output device.
The present invention provides a computer system for locating a short between a first net and a second net such that the short is at a point P
S
at a location on a path between points P
A
and P
B
on the first net, comprising:
a memory device;
input data stored for use by a computer code, said input data including: a voltage drop V
AB
from P
A
to P
B
, a voltage drop V
AC
from P
A
to a point P
C
on the second net, and geometric data describing a spatial distribution of an electrical wire network which includes the first net;
the computer code located on the memory device, wherein the computer code includes a calculation algorithm which utilizes V
AC
, V
AB
, and the geometric data to calculate a length L
AS
along the path from P
A
to P
S
as a function of V
AC
/V
AB
;
a processor which executes the computer code; and
an output device which receives output from the computer code, said output including output data selected from the group consisting of L
AS
, a graphical image displaying a location of the short, and a combination thereof.
The present invention provides a computer program product, comprising:
a computer usable medium having a computer readable program code embodied therein for locating a short between a first net and a second net such that the short is at a point P
S
at a location on a path between points P
A
and P
B
on the first net, wherein the computer readable program code includes:
a utilization of input data for locating the short, wherein the input date comprises: a voltage drop V
AB
from P
A
to P
B
, a voltage drop V
AC
from P
A
to a point P
C
on the second net, and geometric data describing a spatial distribution of an electrical wire network which includes the first net and the second net, and
a calculation of locational information selected from the group consisting of a length L
AS
along the path from P
A
to P
S
as a function of V
AC
/V
AB
, a graphical image displaying a location of the short, and a combination thereof.
The present invention provides a method, apparatus, and computer program product for accurately, efficiently, and nondestructively locating an electrical short between two nets in an electrical network of a microelectronic structure.


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