Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – With provision to conduct electricity from panel circuit to...
Reexamination Certificate
2001-11-01
2002-08-27
Ta, Tho D. (Department: 2833)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
With provision to conduct electricity from panel circuit to...
C439S066000, C439S071000
Reexamination Certificate
active
06439897
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to a socket for removably mounting an electronic part that has a large number of terminals on its lower surface in order to electrically connect each terminal to a circuit path which in turn is connected to test equipment for testing such electronic parts and more particularly to sockets of the type which employ a flexible contact sheet or film as a contact interface member.
BACKGROUND OF THE INVENTIONS
It is conventional to subject semiconductor (IC) packages having resin sealed IC chips to various tests including a reliability test, called a burn-in test, to identify packages which do not meet required specifications. One such socket for use with semiconductor packages having terminals arranged in a Ball Grid Array (BGA) is shown in FIG.
8
. As shown in the figure, socket
101
has a rectangular base
102
and a cover
103
pivotably mounted on the base and being movable between an opened position away from the base and a closed position engaged with the base. A contact film support
105
, capable of supporting a contact film
104
, to be described later, is provided at the central part of base
102
. A thin flat rubber sheet
106
is disposed in a recessed portion formed on the upper surface of support
105
. Compression coil springs
107
disposed between support
105
and base
102
provide an upwardly directed bias to support
105
.
With reference to
FIG. 9
, a generally square shaped contact film
104
has a plurality of inner conductive pads
104
b
arranged at the center of the film in conformity with the pattern of solder balls
108
a
of BGA package
108
. Inner pads
104
b
are respectively connected to outer conductive pads
104
d
arranged along the outer peripheral part of film
104
a
through a selected wiring pattern
104
c.
Again, with reference to
FIG. 8
, an adapter
109
, capable of seating BGA package
108
with solder balls
108
a
exposed in an opening in the adapter, is removably provided on support
105
of base
102
. Adapter
109
is placed over contact film
104
with the inner pads
104
b
of contact film
104
disposed at the opening of the adapter and with the outer peripheral part of the contact film bent by rib
109
a
of the adapter into a recess
102
a
formed in the base. The outer peripheral part of the contact film is received between rib
109
a
and contacts
111
mounted in the recess with the outer pads
104
d
electrically connected to respective contacts
111
. Thus, an electrical connection is made from solder balls
108
a
to inner pads
104
b
which are connected by wiring pattern
104
c
to outer pads
104
d
and then to contacts
111
which in turn are connected to external substrate
110
.
Cover member
103
has a compression member
112
for engaging adapter
109
as well as a BGA package
108
received in adapter
109
. Compression member
112
is biased in a direction away from cover member
103
by means of a compression coil spring
113
.
A BGA package
108
is arranged on contact film
104
through the opening in adapter
109
and cover member
103
is then closed, thereby causing the solder balls
108
a
of the BGA package and respective inner pads
104
b
of the contact film
104
to be connected with a compressive force applied from both base
102
through support
105
and cover member
103
through engagement portion
112
. In the prior art socket described above, rubber sheet
106
which is interposed between support
105
and contact film
104
is plastically deformed when it is heated in a compressed state in connection with burn-in tests, thereby adversely affecting the effectiveness of the desired function of elastically receiving BGA package
108
and contact film
104
between support
105
and engagement member
112
. As a result, it has been difficult to produce a suitable pressure between solder balls
108
a
of BGA package
108
and respective inner pads
104
b
of contact film
104
by merely employing the compression coil springs
107
and
113
through support
105
and engagement member
112
. Further, with respect to contact film
104
used in the prior art socket, it has been necessary to arrange the same number of inner pads
104
b
and outer pads
104
d
as the solder balls
108
a
of the BGA package as well as the number of interconnecting paths between respective inner and outer pads. As the number of the solder balls of BGA package
108
increase, the inner pads
104
b
of the contact film are made smaller, thereby making it more difficult to form a wiring pattern
104
c
on contact film
104
. Although it may be possible to form the contact film as a multi-layer substrate in order to facilitate forming the interconnections, such a substrate reduces flexibility, thereby making it unsuitable for use in this kind of socket.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a socket free of the above described prior art limitations. Another object of the invention is the provision of a socket in which the electrical connection between the terminals of an electronic package and the contacts of an interface contact film are optimized. Yet another object is the provision of a socket having an interface contact film particularly adapted for electronic packages having a large number of terminals.
A socket made in accordance with a preferred embodiment of the invention comprises a base wherein electrically conductive contact members capable of contacting each terminal of an electronic package having terminals arranged according to a selected pattern and a plurality of electrically conductive spring contact elements capable of applying force to the contact members from below are mounted and aligned respectively with each terminal of the electronic package. A compression member capable of moving in a direction either toward or away from the base is provided for applying a force from above tending to compress the spring contact elements.
According to a feature of the invention, the contact members are mounted on an interface contact film which is received on a surface of a support member which is also formed with a plurality of bores therethrough in alignment with the contact members of the contact film. The electrically conductive spring contact elements are in the form of a coil spring received in each bore and adapted to apply a force to each contact member of the contact film from below.
According to another feature of the invention, an adapter is provided capable of accommodating an electronic package and exposing the package terminals and each of the contact members. The terminals of the electronic package are connectable with the contact members of the interface contact film which is arranged between the adapter and the base, and a cover is provided that has a compression member capable of applying a force to the electronic package against the spring contact elements. The cover is mounted on the base and is pivotable between opened and closed positions in linkage with the compression member.
According to another feature of the invention, an inter-terminal pitch expansion substrate can be installed in the socket. The substrate has a plurality of terminals spaced apart a distance greater than the distance between the terminals of the electronic package inter-connected to the spring contact elements through a selected wiring pattern on the substrate.
According to yet another feature of the invention, the spring contact elements comprise a first axial length coil portion having a selected outer diameter and a second axial length coil portion having an outer diameter which is greater than the outer diameter of the first coil portion. The plurality of bores formed through the support member for receiving the spring contact elements have a first bore portion formed larger than the outer diameter of the first axial length portion and a second bore portion having a diameter formed somewhat smaller than the outer diameter of the second coil portion allowing fixation of the second coil portion in a respective bore of the sup
Baumann Russell E.
Nguyen Truc
Ta Tho D.
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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