Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – With provision to conduct electricity from panel circuit to...
Reexamination Certificate
2001-02-22
2002-10-15
Vu, Hien (Department: 2833)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
With provision to conduct electricity from panel circuit to...
C439S700000
Reexamination Certificate
active
06464511
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an integrated circuit (IC) testing apparatus, and more particularly to the construction of an IC socket onto which semiconductor devices being tested (ICs being tested) are to be placed for electrical connection and which is superior in the contact stability.
THE BACKGROUND ART
FIG. 5
is a schematic view illustrating the exterior appearance of a prior art IC socket of this type, and
FIG. 6
shows the details of the construction thereof. The IC socket
11
comprises a plastic housing
13
in which a number of probe pins
12
are carried. In the illustrated example, the IC socket
11
is adapted to accommodate CSPs (Chip Size Packages) such as BGA (Ball Grid Array) and has a grid array of several tens of probe pins
12
. It is to be understood that in
FIG. 5
the probe pins
12
are symbolized to illustrate only the positions of the array of the pins.
As shown in
FIG. 6
, each of the probe pins
12
comprises a metallic tube
14
, a fixed plunger
15
integrally fixed to the tube at one end thereof, and a movable plunger
17
disposed at the opposite end and biased by a coil spring
16
. A tube assembly
18
comprising the tube
14
and the fixed plunger
15
is held in place by the housing
13
and a bottom cover
21
with one end portion of the tube assembly accommodated in a through-aperture
19
formed through the housing
13
and the other end portion accommodated in a through-aperture
22
formed through the bottom cover
21
. The bottom cover
21
is made of resin and is fastened to the housing
13
as by screws, not shown in FIG.
6
.
The IC socket
11
is mounted on a socket board in use and devices to be tested are successively mounted on the IC socket in that state to be subjected to testing.
FIG. 7
shows how the probe pin
12
works during the testing. Specifically,
FIG. 7A
shows the probe pin
12
before the IC socket
11
is mounted on the socket board
23
;
FIG. 7B
shows the probe pin
12
after the IC
11
socket has been mounted on the socket board
23
; and
FIG. 7C
shows the probe pin
12
when a device
24
to be tested is mounted on the IC socket
11
.
When the IC socket
11
is mounted on the socket board
23
, the movable plunger
17
of the probe pin
12
is urged upwardly by an electrode pad
25
on the socket board
23
as shown in
FIG. 7B
whereby the entire probe pin
12
is moved upward until stop means
14
a
formed on the outer periphery of the tube
14
comes into abutment against the interior wall
13
a
of the housing
13
. Further urging by the electrode pad forces the movable plunger
17
into the tube to compress the coil spring
16
, so that the movable plunger
17
and the electrode pad
25
are maintained in pressure contact by the restoring force of the coil spring
16
.
FIG. 7C
illustrates the device
24
to be tested as being a BGA having solder balls
24
a
as terminals. As the device
24
being tested is loaded on the IC socket
11
, the solder ball
24
a
presses on the fixed plunger
15
whereby the tube assembly
18
is moved downwardly while the coil spring
16
is further compressed, so that the solder ball
24
a
and the fixed plunger
15
are maintained in pressure contact by the restoring force of the coil spring
16
.
Upon completion of the testing, the device
24
being tested is removed whereupon the tube assembly
18
is moved upwardly back to the position shown in FIG.
7
B.
As discussed above, it is to be noted that the conventional IC socket
11
is configured such that the tube assembly
18
is moved up and down as the device
24
being tested is removed from and mounted on the socket, respectively.
However, the thus constructed IC socket
1
has often encountered a situation in which the tube assembly
18
fails to return to its original position even though the device
24
under test has been removed. That is, there has often occurred the situation in which the tube assembly
18
remains pushed in so that when the next device
24
to be tested is loaded on the socket no good contact is established between the device and the socket.
Occurrence of such contact failure results in a test failure. If retesting is conducted to determine whether the test failure is due to failure of the device
24
being tested itself or to contact failure of the IC socket
11
, it results in a marked increase in the average number of man-hours needed for testing. In addition, since even the retesting cannot insure that such failures distinguished one from the other, it leads to a deterioration in production. For this reason, the failure of the tube assembly
18
to return to its original position has become a serious problem.
Such failure of the tube assembly
18
to return to position arises from reduction in slidability of the tube
14
. More specifically, the tube
14
is provided around its outer periphery with a stop projection
14
a
as described above. The stop projection
14
a
is formed by removing, by machining operation, the rest of the outer peripheral material of the miniature tube
14
made by a drawing process other than the stop projection
14
a
forming portion. Hence, the slide surfaces of the tube
14
are machined surfaces having rather poor surface roughness, so that those surfaces will scratch or abrade the opponent slide surfaces of the housing
13
and bottom cover
21
and produce wear debris which will accumulate in gaps between the tube
14
and the through-apertures
19
,
22
, resulting in poor slidability.
It is also to be noted that the tube
14
is configured so as to be positioned by both of the through-aperture
19
in the housing
13
and the through-aperture
22
in the bottom cover
21
for sliding movement along the aperture walls. Consequently, if there is some misalignment in assembly between the housing
13
and the bottom cover
21
, for example and hence the opposing through-apertures
19
and
22
are out of alignment with each other, radial forces may be exerted on the tube
14
to impair the slidability of the tube, resulting in an increase in resistance to the sliding movement which in turn brings forth a situation in which wear debris is more likely to be produced.
Accordingly, it is an object of this invention to provide an IC socket which overcomes the aforesaid drawbacks to the prior art IC socket and which has a superior contact stability attended with no deterioration of slidability.
It is another object of this invention to provide an IC testing apparatus equipped with such IC sockets having a superior contact stability.
DISCLOSURE OF THE INVENTION
According to this invention, in an IC socket comprising a housing and a bottom cover integrally secured together, the housing and the bottom cover each having an array of through-apertures formed therethrough, the through-apertures in the housing and the associated through-apertures in the bottom cover being in opposing alignment with each other, and a probe pin being accommodated and held in each pair of the opposedly aligned through-apertures, each of the probe pins comprising: a tube assembly including a tube having a narrowed one end and a stop means in the form of a flange formed around the outer periphery of the tube intermediate its opposite ends and a fixed plunger fixedly fitted in the other end of the tube; a movable plunger having a base portion accommodated in the tube and restrained by the narrowed one end against axial dislocation therefrom and an extension extending from the base portion out through the narrowed one end and adapted to make pressure contact with a terminal of a device being tested; a first resilient member housed in the tube to urge the movable plunger in such a direction as to extend the plunger out of the narrowed one end; and a second resilient member surrounding the tube and interposed between the inner surface of the housing and the stop means, wherein the tube assembly is held in position with its opposite ends accommodated in the associated pair of opposedly aligned through-apertures, the stop means being urged by the second resilient member i
Takeshita Satoshi
Watanabe Fumio
Advantest Corporation
Figueroa Felix O.
Gallagher & Lathrop
Lathrop, Esq. David N.
Vu Hien
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