Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – With provision to conduct electricity from panel circuit to...
Reexamination Certificate
2003-09-05
2004-10-19
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...
C439S067000, C439S086000, C439S493000, C439S331000
Reexamination Certificate
active
06805563
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a socket for electrical parts for detachably holding and accommodating electrical parts such as a semiconductor device (which is called herein as an “IC package”) or the like, to conduct electrical performance test and examination of the electrical parts, and more particularly, making improvements in the contact stability between the socket for electrical parts and the electrical part.
2. Prior Art of the Invention
In a known art, there has been provided an IC socket, as “socket for an electrical part” for detachably holding and accommodating an IC package as an “electrical part”.
Such IC package includes BGA (Ball Grid Array) type, in which a number of spherical solder balls (terminals) are arranged to the lower surface of the rectangular package body projecting downward in a matrix arrangement.
On the other hand, aforementioned IC package is positioned to be accommodated on the accommodation surface portion of a socket body of the IC socket at a predetermined position, and the solder balls of this IC package each make contact with the contact point of a tab film, a sheet like base plate to establish electrical connection when the performance test of such IC package is being conducted.
Further more, an elastic member is provided on the lower surface of the tab film to prevent the solder balls from being damaged and to enhance the contact stability between the solder ball and the contact point of the tab film. (Please refer to the Japanese laid open patent publication No. Hei 11-242977)
FIG. 10
is a sectional view showing a contact state of the solder ball
2
a
of the IC package
2
accommodated on the accommodation surface portion of the IC socket and the tab film
5
in a conventional IC socket. The tab film
5
is formed with a contact point
5
a
to which solder ball
2
a
contacts at a position corresponding to the solder ball
2
a
. To the lower side of the tab film
5
, an elastic member
4
, a plate shape body having elasticity made of silicon rubber is disposed.
In such IC socket, after the IC package
2
is mounted on the tab film
5
, the package body
2
b
is pressed downward the amount as prescribed, accordingly the elastic member
4
is elastically deformed through the solder ball
2
a
and the tab film
5
. By reaction force from this elastic deformation, a predetermined contacting pressure is produced between the solder ball
2
a
and the contact point
5
a
on the tab film
5
, to ensure electrical contact between the solder ball
2
a
and the contact point
5
a.
However, in the conventional structure of such IC socket, the projection amount (height) from the lower surface of the package body
2
b
to the lowermost point of each solder ball
2
a
happens to vary with in the range of n &mgr;m to 10 n&mgr;m (n:1-9 integer) due to the curving of the package body
2
b
, due to the difference in the diameter of the solder ball
2
a
, and due to the variation occurring when mounting the solder ball
2
a
to the package body
2
b
or the like.
When IC package
2
having such variation in the projection amount of the solder ball
2
a
is to be mounted on to the conventional IC socket, solder balls
2
a
each having approximately same amount of projection from the lower surface of the package body
2
b
to the lower most point of the solder ball
2
a
, establish electrical contact with the contact points
5
a
of the tab film
5
at a predetermined contacting pressure as shown in
FIG. 10
, respectively, by pushing the package body
2
b
downward the amount as prescribed. At this time, the elastic member
4
is elastically deformed predetermined amount through the solder ball
2
a
and the tab film
5
.
In this state, the elastic member
4
is formed to have a plate like body (one sheet with plane surface). And in the vicinity of the contact point
5
b
of the tab film
5
corresponding to the solder ball
2
c
having smaller projection amount from the package body
2
b
than that of the solder ball
2
a
, the elastic member
4
is pressed downward (elastically deformed) as shown in
FIG. 10
by the solder ball
2
a
adjacent to the solder ball
2
c
, unable to make contact between the solder ball
2
c
and the contact point
5
b
. Or else, even if the solder ball
2
c
and the contact point
5
b
are able to be contacted, the elastic member
4
is unable to be pressed (elastically deformed) the amount prescribed therefore stability of the electrical contact between the solder ball
2
c
and the contact point
5
b
can not be maintained.
In order to ensure electrical contact even in the IC package
2
having solder ball
2
c
with small amount of projection, it is necessary to make larger the pushing amount for pressing downward the IC package
2
in response to the solder ball
2
c
with small amount of projection. In this, operating force of the member for pressing downward the IC package may become larger and the solder ball
2
a
with large amount of projection may be damaged and destroyed.
SUMMARY OF THE INVENTION
An object of the present invention is to substantially eliminate defects or drawbacks encountered in the related art mentioned above and to provide a socket for electrical parts capable of maintaining the contact stability even when there is a variation in the amount of the downward projection of the solder ball (terminal) of the IC package, and reducing the operating force toward the member for pressing downward the IC package and, preventing the solder ball from being damaged and destroyed.
This and other objects can be achieved according to the present invention by providing a socket for electrical parts comprising;
a base member;
an elastic member disposed on the base member; and
a base plate, in the form of deformable sheet, disposed on the elastic member, and provided with a plurality of contact points to which a plurality of terminals of an electrical part is to be contacted, disposed on the upper surface of the base plate in a predetermined distance;
when a position corresponding to each contact point of the elastic member is compressed by the pressing force from the terminal of the electrical part, an escaping space is provided for elastic deformation portion pushed away by the compression and is disposed at a position corresponding in between each terminal.
Another aspect of the present invention is characterized by that the elastic member is formed with a protrusion projecting toward the base plate at a position corresponding to each contact point, and in between such protrusions, the escaping space is formed.
Still another aspect of the present invention is characterized by that the elastic member is formed with a protrusion projecting toward the base member at a position corresponding to each contact point, and in between such protrusions, the escaping space is formed.
Another aspect of the present invention is characterized by that the base member is formed with a protrusion projecting toward the elastic member at a position corresponding to each contact point, and in between such protrusions, the escaping space is formed.
According to the present invention of the characteristics and structures mentioned above, when the position corresponding to each contact point of the elastic member is compressed by the pressing force from the terminal of the electrical part, an escaping space is provided for the elastic deformation portion which is pushed away by the compression to be escaped at a position corresponding to a position in between each terminal, so that the portion corresponding to the terminal of the elastic member can be elastically deformed independently without being affected by the surrounding deformation. Accordingly, this portion corresponding to the terminal will also be deformed following the deformation of the terminal and the base plate even when there is a variation in the projection amount of the terminal, thereby ensuring the contact stability and preventing the contact pressure of the terminals from varying, and also preventing the ter
Enplas Corporation
Ta Tho D.
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