Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2001-10-22
2003-09-02
Cuneo, Kamand (Department: 2829)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S1540PB
Reexamination Certificate
active
06614247
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to sockets for removably mounting electronic packages, such as a package containing an integrated circuit, for conducting electrical tests of such packages and more particularly to such sockets in which each conductive terminal of an electronic package is electrically connected to a respective lead in the socket for further connection to testing equipment.
BACKGROUND OF THE INVENTION
IC (integrated circuit) packages in which an IC chip has been sealed by resin are typically subjected to a reliability test called a burn-in test to separate them into satisfactory and unsatisfactory products.
FIGS.
13
(
a
)-
13
(
d
) show an example of a known socket
101
used in burn-in tests for electronic packages having BGA (Ball Grid Array) terminals. Socket
101
has a square-shaped base
102
in which are mounted a plurality of contacts
104
for a pressure connection of respective solder balls
100
a
of a BGA package
100
. Contacts
104
are each made of an elongated metal member, with a pair of arms
104
a
and
104
b
being provided at one end thereof. A slider
105
capable of carrying BGA package
100
is mounted on base
102
for movement in the horizontal direction (X direction). Slider
105
is adapted to accommodate contacts
104
through contact receiving holes
105
a
. As shown in FIGS.
13
(
a
),
13
(
b
), respective ball receiving holes
105
c
for accommodating each solder ball
100
a
are formed on seat
105
b
of slider
105
in such a manner as to cross the contact accommodation hole
105
a
. As shown in FIG.
13
(
b
), further, respective engagement parts
105
d
of slider
105
are formed inside of contact receiving holes
105
a
for engagement with arms
104
a
of respective contacts
104
. A cover
106
for operating slider
105
is provided on base
102
for movement toward and away from base
102
through compression coil springs
107
.
In a socket as described above, if cover
106
is pressed down, slider
105
moves in the X+ direction, causing arms
104
a
of contacts
104
to engage with engagement parts
105
d
of slider
105
, thereby opening the contacts in the X+ direction in a bent state. When, in this state, the BGA package
100
is dropped onto seat
105
b
of slider
105
, each solder ball
100
a
of BGA package
100
is accommodated in a respective ball receiving hole
105
c
. When cover
104
is raised, slider
105
is returned in the X− direction by the force of arms
104
a
of contacts
104
. As a result, each arm
104
a
contacts a respective solder ball
100
a
and, at the same time, the other arm
104
b
bends in the X− direction as it is pushed by solder ball
100
a
. Each pair of arms
104
a
and
104
b
sandwich a solder ball
100
a
, so that each solder ball
100
a
of the BGA package is electrically connected to a contact
104
.
In the above arrangement, arms
104
a
and
104
b
move in connection with the opening of arms
104
a
and the holding of the solder ball
100
a
by both arms
104
a
and
104
b
. Accordingly, it has been necessary to provide an area large enough to conform to the amount of movement of arms
104
a
and
104
b
in seating portion
105
b
of slider
105
. Since there is a physical limitation as to how close contacts
104
can be arranged, it has been difficult to use a conventional socket
101
for BGA packages having solder balls that have been arranged in finer pitches.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the above noted problems of the prior art. Another object of the invention is the provision of a socket which is adaptable for use with IC packages of finer pitches.
Briefly described, a socket made in accordance with a preferred embodiment of the invention for removably receiving an electronic part having terminals arranged according to a selected pattern comprises a socket base having a plurality of contacts arranged corresponding to the selected pattern, each having a cantilever-like contact arm capable of contacting a terminal of an electronic part. A slider capable of moving in a horizontal direction relative to the socket base is slidably mounted on the base and has a plurality of contact receiving through-holes that correspond to the positions of the contact arms. The walls of the through-holes are arranged so that they apply no bias to the contact arms allowing them to function as free ends. The slider is also formed with terminal receiving holes for accommodating the terminals and which communicate with the through-holes. The terminals can be accommodated in the terminal receiving holes when the slider is at a selected position and the arms can be flexibly connected with the terminals in the terminal receiving holes when the slider is at another selected position.
According to a feature of the invention, the contacts are each formed with a single contact arm rather than the conventional pair of squeezable arms and the terminals of the electronic part are engaged in the terminal receiving holes upon movement of the slider, thereby making it possible to connect each respective terminal of the electronic part by holding such terminal between a wall, i.e., a terminal engagement surface in a terminal receiving hole, and an arm of a contact. Accordingly, only enough space need be provided on the slider which corresponds to the range of movement required for the terminals of the electronic part to be connected with the arms of the contacts under a suitable force so that the area that the contact arm occupies on the slider seat can be smaller than that provided in the prior art. As a result, terminals with a finer pitch can be accommodated. According to another feature of the invention, a cover is provided which is capable of moving in a direction toward or away from the socket base. The cover has an engagement portion capable of engaging the slider to move the slider in a selected direction as the cover moves toward or away from the socket base when the engagement portion is in engagement with the slider. In accordance with the invention, the contacts are bent only when they are engaged with terminals of the electronic part, thereby enhancing the durability of the contacts. According to another feature of the invention, the terminal engagement surface of the terminal receiving hole can be a cylindrical surface or it can be configured in greater conformity with the surface shape of the terminals of the electric part with which the socket is used, e.g., partly spherical for solder ball terminals.
According to a feature of the invention, the contacting portion of the contact arms can be formed with projections, for example, in the shape of a claw having a pair of spaced apart projections extending in selected directions so that when mounted they extend toward the terminal engagement surfaces. Thus, the contacts can be stably connected with the terminals of the electronic part in a contact area that correspond to the contact area of a plurality of arms even when a single arm is employed.
According to yet another feature, the contacting portions of the contact arm are arranged to contact the root portion of the terminals on the side of the electronic part from which the terminals extend. When used with electronic parts having a BGA package with globular terminals, the contacting portion of the contact arms engage the terminals between the bottom surface of the package and that portion of the terminals where the diameter becomes the largest relative to planes parallel to the bottom surface of the package.
According to another feature of an embodiment of the invention, a jig having a holding and releasing part for delivery of an electronic part is movable toward and away from the socket and can be used to move the cover or the slider of a socket having no cover.
Additional objects and features of the invention will be set forth in part in the description which follows and in part will be obvious from the description. The objects and advantages of the invention may be realized and attained by means of t
Ikeya Kiyokazu
Katayose Kyozo
Baumann Russell E.
Cuneo Kamand
Nguyen Jimmy
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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