Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2000-11-29
2002-08-27
Le, N. (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S1540PB, C324S523000, C324S754090
Reexamination Certificate
active
06441621
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a waveform observing jig and a waveform observing device, which are used for observing a waveform of a signal by an IC tester or the like.
2. Description of the Related Art
A waveform of a signal is tested by an IC tester or the like. A waveform observation or the like, for a timing calibration of a waveform signal is carried out. When such a waveform observation or the like is carried out, a board to be observed is used. A waveform observing jig
100
shown in
FIG. 3
is used for observing a signal outputted from the board to be observed.
The waveform observing jig
100
shown in
FIG. 3
comprises a contact
10
for a signal, a contact
20
for a ground (GND), a conductive block
40
, an insulator
50
and a voltage probe
30
. An oscilloscope
60
observes a waveform of a signal outputted from a board
1
to be observed through the waveform observing jig
100
.
One contact
10
for a signal and one contact
20
for a GND are attached to the waveform observing jig
100
in order to observe a signal outputted from the board
1
to be observed. An end portion
10
a
of the contact
10
for a signal is in contact with a gold-plated pad
3
for a signal, to be measured, which is mounted on the board
1
to be observed. An end portion
20
a
of the contact
20
for a GND is in contact with a GND pattern
2
of the board
1
to be observed. By fetching a signal, the waveform observation is carried out by the oscilloscope
60
.
The contact
10
for a signal is held by the insulator
50
provided in the conductive block
40
. The contact
10
is insulated from the conductive block
40
by the insulator
50
. The contact
10
for a signal is biased toward a lower direction in the figure by a spring or the like, which is not shown. When the end portion
10
a
of the contact
10
for a signal is in contact with the gold-plated pad
3
for a signal, the other end portion
10
b
of the contact
10
for a signal is in contact with an end portion
30
a
of the voltage probe
30
.
The contact
20
for a GND is arranged on the conductive block
40
at a predetermined interval from the contact
10
for a signal so as to be in contact with the GND pattern
2
even when the contact
10
for a signal is in contact with any gold-plated pad
3
.
A plurality of gold-plated pads
3
-
1
,
3
-
2
, . . . ,
3
-n for a signal are arranged on the board
1
to be observed, so as to fetch a signal outputted from each electrode of an IC to be measured, where n is a natural number and a plurality of gold-plated pads are inclusively represented by gold-plated pads
3
for a signal. The arrangement of the gold-plated pads
3
for a signal is determined on the basis of an arrangement of lead pitches of an IC to be measured. That is, because each gold-plated pad
3
for a signal is arranged according to the lead pitches of an IC to be measured, each signal outputted from the lead pitches of an IC is outputted to the corresponding gold-plated pads
3
for a signal.
The distance from each gold-plated pad
3
for a signal to the GND pattern
2
differs according to the position of a gold-plated pad
3
. Therefore, on the waveform observing jig
100
, the contact
10
for a signal and the contact
20
for a GND are arranged so as to adjust their positions to a distance between the GND pattern
2
and the gold-plated pad
3
which is disposed the most apart from the GND pattern
2
.
FIG. 4A
shows a state in which the contact
10
for a signal is in contact with the gold-plated pad
3
-
1
for a signal. In
FIG. 4A
, when the contact
10
for a signal is in contact with the gold-plated pad
3
-
1
for a signal, to be measured, the contact
20
for a GND is in contact with a point
2
-
1
on the GND pattern
2
. The point
2
-
1
is a reference point of the GND. Then, a signal outputted from the gold-plated pad
3
-
1
for a signal, that is, a signal outputted from a lead pitch of an IC, which corresponds to the gold-plated pad
3
-
1
for a signal, is measured.
FIG. 4B
shows a state in which the contact
10
for a signal is in contact with the gold-plated pad
3
-
4
for a signal. In
FIG. 4B
, when the contact
10
for a signal is in contact with the gold-plated pad
3
-
4
for a signal, to be measured, the contact
20
for a GND is in contact with a point
2
-
4
on the GND pattern
2
. The point
2
-
4
is a reference point of the GND. Then, a signal outputted from the gold-plated pad
3
-
4
for a signal, that is, a signal outputted from a lead pitch of an IC, which corresponds to the gold-plated pad
3
-
4
for a signal, is measured.
However, in the waveform observing jig
100
according to an earlier development, as shown in
FIGS. 4A and 4B
, when the contact
10
for a signal is in contact with every gold-plated pad
3
during the waveform observation, the contact
20
for a GND, which is disposed apart from the contact
10
for a signal at a constant distance, is in contact with the GND pattern
2
in order to set the reference point of the GND. Therefore, the inductance of the GND depends on the position of the gold-plated pad
3
for a signal, to be measured. As a result, there is some possibility that the inductance of the GND becomes large. The waveform of the observed signal is deteriorated. The timing error of the observed signal is caused.
Because the arrangement of the lead pitches differs according to the type of an IC to be measured, it is necessary that a board
1
to be observed, which has a different arrangement of the gold-plated pads
3
for a signal, should be prepared for every type of an IC.
Further, because it is necessary that the contact
10
for a signal and the contact
20
for a GND, of the waveform observing jig
100
should be arranged so as to adjust their positions to a distance between the GND pattern
2
and the gold-plated pad
3
which is disposed the most apart from the GND pattern
2
, the waveform observing jig
100
which is suitable for the board
1
to be observed must be used. That is, it is necessary that the waveform observing jig
100
should be prepared according to the type of an IC to be measured.
SUMMARY OF THE INVENTION
In order to solve the above-described problems, an object of the present invention is to provide a waveform observing jig and a waveform observing device which can minimize the inductance of the GND in the board to be observed during the waveform observation, and can be adapted to various types of boards to be measured.
That is, in accordance with one aspect of the present invention, a waveform observing jig (for example, waveform observing jig
200
, as shown in
FIG. 1
) for observing a waveform of a signal outputted from a predetermined signal terminal, comprises:
a contact for a signal (for example, contact
10
for a signal, as shown in FIG.
1
), for contacting with a signal terminal (for example, gold-plated pad
3
for a signal, as shown in
FIG. 1
) of a board to be observed (for example, board
1
to be observed, as shown in FIG.
1
), and
a plurality of contacts for a ground (for example, contacts
20
for a GND, as shown in FIG.
1
), for contacting with a ground pattern (for example, GND pattern
2
, as shown in
FIG. 1
) of the board to be observed,
wherein at least one contact for a ground is in contact with the ground pattern of the board to be observed when the contact for a signal is in contact with a predetermined signal terminal of the board to be observed.
According to the present invention, because the waveform observing jig comprises a plurality of contacts for a ground, when the contact for a signal is in contact with the predetermined signal terminal of the board to be observed, it is possible to observe a signal from the predetermined signal terminal by using a contact for a ground as a reference, which is the nearest to the contact for a signal in the contacts for a ground, connecting with the ground pattern of the board to be observed, that is, by using a contact for a ground as a reference, by which the inductance of the ground
Ando Electric Co. Ltd.
Le N.
Oliff & Berridg,e PLC
Sundaram T. R.
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