Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2000-10-26
2003-02-04
Nguyen, Vinh P. (Department: 2829)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S761010
Reexamination Certificate
active
06515497
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a test fixture for electrically connecting an in-circuit tester (print-wiring board tester) and a loaded board.
2. Description of the Related Art
Heretofore, as a fixture used for a tester, such as an in-circuit tester, a probe pin and a spring are combined to form a spring probe pin.
Referring to
FIG. 10
, the conventional fixture
41
is constituted by having spring probe pins
42
, sleeves
43
, a top plate
44
, a base
45
, a support stage
46
and springs
47
. The spring probe pins
42
are electrically connected to the sleeves
43
. Also, the sleeves
43
are respectively connected through wirings
48
to a tester
49
.
In this conventional fixture
41
, a loaded board
11
is arranged on the support stage
46
. Then, relative to the loaded board
11
, a force is applied from the upper surface of the loaded board
11
in the arrow direction (downward). The springs
47
arranged under the support stage
46
are compressed, and the loaded board
11
is pressed relative to the top plate
44
. In a short time, connection terminals
13
of the loaded board
11
contact the spring probe pins
42
, and the fixture
41
and the loaded board
11
are electrically connected. At this time, the spring probe pins
42
absorb a pressing force from the loaded board
11
by compressing its spring inside the sleeves
43
.
Alternatively, referring to
FIG. 11
, this conventional fixture
51
includes spring probe pins
52
, sleeves
53
, a top plate
54
, a base
55
, a support stage
56
, springs
57
and an air hole
59
as an air gateway. The springs
57
support the loaded board
11
and the support stage
56
. The spring probe pins
52
are electrically connected to the sleeves
53
. Moreover, the sleeves
53
are connected through the wirings
58
to the tester
60
. Furthermore, to the air hole
59
, a suction pump
61
for evacuating air inside the fixture
51
is connected.
In this conventional fixture
51
, the loaded board
11
is arranged on the support stage
56
. When the loaded board
11
is arranged on the support stage
56
, a closed space, which is surrounded by the sleeves
53
, the top plate
54
, the base
55
and the loaded board
11
, is made on the upper surface of the fixture
51
. Then, by the suction pump
61
, the air in the closed space is evacuated through the air hole
59
. As the suction pump
61
evacuates the air in the closed space made on the upper surface of the fixture
51
, the closed space gradually falls into a vacuum state. As the closed space falls into a vacuum state, the springs
57
are compressed, and the loaded board
11
is drawn to the top plate
54
. The connection terminals
13
of the loaded board
11
contact the spring probe pins
53
as shown in FIG.
12
. The loaded board
11
and the fixture
51
are electrically connected.
In the above-described conventional fixture
41
, since a pressure is directly applied to the loaded board
11
, it has been greatly feared that the loaded board
11
may suffer damage.
Moreover, the conventional fixture
51
has drawn the loaded board
11
to the top plate
54
by making the closed space made between the fixture
51
and the loaded board
11
vacuum. However, attraction by vacuum is directly applied to the loaded board
11
, hence it has also been feared that the loaded board
11
may suffer damage.
Furthermore, in general, the loaded board
11
has some warp due to heat at the time of mounting devices
12
, or the connection terminals
13
of the loaded board
11
are uneven due to manufacturing variation. However, as the spring probe pins
52
, the ones having a constant stroke are used. For this reason, in order to secure the connection between the connection terminals
13
and the spring probe pins
52
, the loaded board
11
has been required to be pressed to the spring probe pins
52
so as to absorb the warp of the loaded board
11
or the unevenness of the connection terminals
13
.
Accordingly, a force more than necessary is applied to the loaded board
11
depending on the connection terminals
13
of the loaded board
11
, as well as it is connected to the spring probe pins
52
, hence the connection terminals
13
receive a excessive load from the spring probe pins
42
or
52
. As such, in the conventional fixtures
41
and
51
, a force more than necessary is applied to the loaded board
11
depending on the connection terminals
13
of the loaded board
11
. As a result, it has been feared that the warp of the loaded board
11
may occur.
Heretofore, such warp occurred due to the load of the spring probe pins
42
or
52
has been able to be neglected to some extent. However, in such a case like a bear chip loaded board before resin sealing, which has been used in recent years, since bear chip connection terminals are damaged due to the warp of the board, such warp are not being able to be neglected.
SUMMARY OF THE INVENTION
The object of the present invention, in consideration of the foregoing problems, when a test fixture is connected electrically to a loaded board, to provide a test fixture capable of performing secure electrical connection without using spring probe pins or applying an excessive load to connection terminals of the loaded board.
In order to solve the foregoing subjects, a test fixture of the present invention includes a plurality of sleeves, and a plurality of probe pins, each is arranged slidable within a corresponding sleeve and making electrical contact with the sleeve; and an air source connected to the plurality of sleeves, wherein the probe pins are slidable by an air pressure from the air source to electrically connect to connection terminals of a loaded board positioned on the test fixture.
Moreover, the test fixture further includes a base with supports for the loaded board and a top plate in which the sleeves are arranged, wherein the probe pins are slidable by an air pressure generated by injecting air into a space, which is formed by the base, the top plate, the sleeves and the probe pins.
REFERENCES:
patent: 2954521 (1960-09-01), McKee
patent: 3714572 (1973-01-01), Ham et al.
patent: 4138643 (1979-02-01), Beck et al.
patent: 5124646 (1992-06-01), Shiraishi
patent: 62-245975 (1987-10-01), None
patent: 10-153622 (1998-06-01), None
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