Electrical connectors – Coupling part having handle or means to move contact...
Reexamination Certificate
2000-07-13
2002-02-26
Nguyen, Khiem (Department: 2839)
Electrical connectors
Coupling part having handle or means to move contact...
Reexamination Certificate
active
06350138
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a socket for removably mounting an electronic part which has a large number of terminals on its lower surface and for electrically connecting each terminal to external equipment and more particularly to a socket which is suitable for BGA (Ball Grid Array) packages.
BACKGROUND OF THE INVENTION
Generally, resin sealed IC packages are subjected to an electrical property and/or reliability test called a burn-in test prior to their shipment from the semi-conductor manufacturer in order to distinguish between acceptable and defective products. In electrical property tests, the input-output characteristics, pulse properties, noise leeway, and the like, of the IC chip are tested. According to the burn-in test, on the other hand, IC packages which have passed the electrical property test are arranged in an oven and are operated for a certain period of time at a power source voltage which is approximately 20% higher than the rated value and at an elevated temperature, such as 125° centigrade, for example. IC packages found to be unsatisfactory in the burn-in test are separated with only those IC packages that continued operating satisfactorily shipped out as acceptable products.
BGA packages having terminals comprising spherically-shaped solder balls arranged in a selected matrix such as in a zigzag fashion on the lower side of the package have become popular. Among the advantages of BGA packages are: the terminal pitch can be widened while maintaining a small outside dimension and the terminal is sturdy, thereby making it less likely to be damaged in case of engagement with some other part.
FIGS.
10
(
a
) through
10
(
c
) show prior art sockets for burn-in tests for loading a BGA package. As shown, socket
101
has a square base
102
made of resin and, on base
102
, a slider
103
for mounting the BGA package
100
is arranged for movement in the horizontal direction for the purpose of mounting BGA package
100
. A cover
104
made of resin and having an opening
104
a
is disposed on top of base
102
. Cover
104
is movable upwardly away from the base and downwardly toward the base by a compression coil spring
105
. A bore is formed through slider
103
and base
102
that corresponds to each solder ball
100
a
of the BGA package. A contact
106
for the pressure connection of solder ball
100
a
of the BGA package is so arranged as to run through respective bores of slider
103
and base
102
. Each contact
106
is made of a longitudinal metallic member having a tip end formed with a pair of arms
106
a
and
106
b
. As shown in FIGS.
10
(
a
) through
10
(
c
), each contact
106
is fixed to base
102
and extends in a direction generally perpendicular to the top and bottom surfaces with arms
106
a
and
106
b
facing upwardly. As shown in FIG.
10
(
c
), contact
106
is formed in such a way that arms
106
a
and
106
b
open by means of a tab (not shown in the drawing) provided on arm
106
a
which is engaged with the partition wall
103
a
of slider
103
.
A slide mechanism for moving slider
103
in parallel with the bottom surface of the base
102
is provided on both sides of slider
103
. The mechanism includes a lever member
108
which is approximately in the shape of an L installed for free rotatable motion at both ends of a shaft
109
which has been provided on one of the edges (the right-hand edge in the drawing) of base
102
and the short arm
108
a
of this lever member
108
is linked, freely rotatable, to shaft
107
received in vertically extending slots formed in slider
103
. In addition, a lever member
111
is mounted, freely rotatable, on both ends of shaft
110
that has been provided on the other opposite side of base
102
and the tip of lever member
108
is mound freely slidable in a slot, at the middle part of lever member
111
by means of a pin
112
. Moreover, the tip
111
a
of lever member
111
engages protuberant part
104
a
of the ceiling surface of cover
104
when the cover is in its raised position. In addition, there is provided a compression coil spring
113
for biasing the slider
103
to the right as seen in FIGS.
10
(
a
),
10
(
b
).
In a socket
101
made as described above, when the cover
104
is pressed downwardly from the position shown in FIG.
10
(
a
) to that shown in FIG.
10
(
b
), lever members
108
and
111
rotate toward base
102
and, in conformity with the movement of lever member
108
, shaft
107
biases slider
103
moving the slider in the X-direction (to the left as seen in FIGS.
10
(
a
),
10
(
b
). As a consequence of this, one arm
106
b
of contact
106
opens in engagement with the partition wall
103
a
of slider
103
. If, in this state, the BGA package
100
is dropped into the adaptor
103
of slider
103
, each solder ball
100
a
of the BGA package
100
enters between the arms
106
a
and
106
b
of a respective contact
106
.
When the force upon the cover
104
is released, moreover, the lever members
108
and
111
also rise and the slider
103
returns in the X+ direction by the force of the compression coil spring
113
, with a consequence that the arms
106
a
and
106
b
of each contact close and that, therefore, each solder ball
100
a
of the BGA package
100
is held by arms
106
a
and
106
b
of each contact
106
. As a result of this, each solder ball
100
a
of the BGA package
100
and each contact
106
can be electrically connected.
In the case of such a socket according to the prior art, however, there has been a problem of inadequate durability of contacts
106
due to a large amount of stress generated in arms
106
b
because of the fact that, in connection with the mounting of the BGA package
100
, the tip part is caused to open by bending arms
106
b
of the contacts
106
. Due to the fact that the center of the opening in which each solder ball
100
a
is to be dropped shifts by the amount of the opening of one of the arms
106
b
, there also has been a problem in that, when the amount of the opening of arms
106
b
has been adjusted, the location, of the drop-in will have to be adjusted so that the solder ball
100
a
may drop into the proper position. In the case of conventional technology, moreover, in connection with the mounting of a BGA package
100
on a socket
101
, there is a situation where the position of the BGA package shifts as the solder ball
100
a
contacts the tip of a contact
106
, with a resultant shifting of the position of the BGA package, thereby causing a contact failure or a mounting failure of the BGA package
100
. In some extreme cases, the tip of a contact
106
is sometimes damaged by solder ball
100
a
of BGA package
100
. According to the prior art, moreover, there is a problem in that the solder ball
100
a
of BGA package
100
and the arms of contact
106
sometimes stick to each other after the completion of the burn-in test, thereby making it difficult to remove the BGA package
100
.
SUMMARY OF THE INVENTION
An object of the present invention is the provision of a socket which avoids the limitations of the prior art described above. Another object is the provision of a socket with improved durability of the contact members that hold the terminals of an electronic part. Yet another object of the invention is the provision of a socket that is capable of preventing any damage to the biased contact parts of the contact members in connection with the mounting of the electronic part as well as improving the mountability of the electronic part. Still another object of the invention is the provision of a socket which is capable of preventing a failure in the removal of the electronic part subsequent to the test.
In accordance with the invention a main socket body is capable of removable loading an electronic part whose terminals are arranged in the main body part according to a selected pattern. A plurality of contact members are arranged on the main socket body in conformity with the arrangement pattern of the terminals of said electronic part. The contact members each have a p
Atobe Takeyoshi
Ezura Toyokazu
Ikeya Kiyokazu
Baumann Russell E.
Nguyen Khiem
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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