Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – With provision to conduct electricity from panel circuit to...
Reexamination Certificate
2001-03-14
2003-01-07
Nguyen, Khiem (Department: 2839)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
With provision to conduct electricity from panel circuit to...
C439S700000
Reexamination Certificate
active
06503089
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a socket for an electrical part for detachably accommodating an electrical part such as semiconductor device (called hereunder “IC package”), and more particularly, a socket for an electrical part having improved contact pins contacting terminals of the electrical part.
An IC socket as a socket for an electrical part having a conventional structure is shown, for example, in
FIGS. 7 and 8
, which corresponds to a structure disclosed in the Japanese Utility Model Laid-open Publication No. SHO 63-61788.
In the structure of the IC socket shown in these figures, a float plate
3
is disposed on a base
5
of a socket body
2
to be vertically movable under a state being upward urged, as viewed, and an IC package
6
is mounted on this float plate
3
.
The IC package
6
includes a package body
6
a
having a lower surface to which a number of terminals
6
b
are arranged with narrow pitch between adjacent ones.
A number of contact pins
7
are electrically connected to the terminals
6
b,
respectively. Each of these contact pins
7
comprises a cylindrical (tubular) piece
7
a,
upper and lower contact pieces
7
b
and
7
c
disposed inside the tubular piece
7
a
and a coil spring
7
d
also disposed inside the tubular piece
7
a
so as to be interposed between the upper and lower contact pieces
7
b
and
7
c.
These contact pieces
7
b
and
7
c
and coil springs
7
d
are formed of conductive materials. In such structure, the upper contact piece
7
b
is urged upward, and the tubular piece
7
a
is inserted under pressure into the socket body
2
, or the tubular piece
7
a
is idly fitted to the float plate
3
and the lower contact piece
7
c
is inserted into an insertion hole
9
a
formed to a printed circuit board
9
to thereby establish an electrical connection. The socket body
2
is fastened to the printed circuit board by means of bolts
10
or like.
Furthermore, a radiation (radiator) plate
11
is disposed above the IC package
6
so as to press the IC package
6
from the upper side thereof, and both end portions of this radiation plate
11
is depressed by a rotatable (pivotal) pressing members
12
.
By depressing downward the radiation plate
11
by the pressing members
12
, the IC package
6
is also depressed downward and the terminal
6
b
is pressed by the upper contact piece
7
b
of the contact pin
7
. Accordingly, the IC package
6
is electrically connected to the printed circuit board
9
through the upper contact piece
7
b,
the coil spring
7
d
and the lower contact piece
7
c.
At this time, the upper contact piece
7
b
is vertically displaced and contacted under pressure to the terminal
6
b
of the IC package
6
by the urging force of the coil spring
7
a,
thus being electrically contacted thereto.
However, in the conventional example of the structure mentioned above, the contact pin
7
is composed of the tubular piece
7
a,
the upper contact piece
7
b,
the lower contact piece
7
c
and the coil spring
7
d.
Thus, the contact piece
7
has many constructional elements and assembling steps are complicated and increased.
Moreover, for the IC package
6
, it is required to make small (fine) a pitch of the terminals
6
a
arranged to the lower surface of the package body
6
a,
and accordingly, it is also required to make small a pitch of the contact pins
7
. Furthermore, it is required to widen or make wide an allowance (allowable range) to positional shifting of the terminal
6
b,
and for this reason, it is required to widen an area of a contact portion of the contact pin
7
contacting the terminal
6
b
of the IC package
6
.
In a Ball Grid Array (BGA) type package, particularly, in order to avoid a damage to a portion near the center of the lower portion of a solder ball as terminal, it is necessary to sufficiently ensure an area of a recessed portion formed to the central portion of a contact portion of the contact pin contacting the solder ball. If be not ensured, the lower central portion of the solder ball abuts against a portion, not recessed portion, of the contact portion, and thus, this portion may be damaged.
However, in the contact pin
7
of the conventional structure, the diameter of the tubular piece
7
a
is larger than the upper contact piece
7
b
having a contact portion. Therefore, it is difficult to sufficiently secure the contact portion contacting the terminal, and hence, also difficult to make fine the pitch of the contact pin
7
.
SUMMARY OF THE INVENTION
An object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art mentioned above and to provide a socket for an electrical part having a structure capable of reducing the number of constructional parts or elements and assembling steps thereof.
Another object of the present invention is to provide a socket for an electrical part capable of ensuring a sufficient area of a contact portion of the contact pin contacting a terminal of the electrical part with fine pitch.
These and other objects can be achieved according to the present invention by providing, in one aspect, an IC socket for an electrical part in which a contact pin electrically connecting a terminal of an electrical part and a printed circuit board is provided for a socket body of an IC socket, wherein the contact pin comprises a sleeve having a space having one end opening, a plunger inserted into the sleeve through the end opening thereof to be vertically movable and an elastic member for urging downward the plunger in an vertical attitude of the contact pin, and the sleeve is arranged to be vertically movable with respect to the socket body and is provided with a contact portion formed to an upper end thereof contacts a terminal of the electrical part to be electrically connected thereto and the plunger has a lower end contacting the printed circuit board to establish an electrical connection therebetween.
In preferred embodiments of this aspect, the plunger is arranged to be vertically movable with respect to the socket body. The sleeve and the plunger are disposed to be relatively slidable to thereby establish an electrical connection therebetween. The contact portion of the sleeve is formed with a central recessed portion and/or the contact portion of the sleeve is formed with a plurality of sharp protruded portions.
In a more detailed aspect, there is provided an IC socket for an electrical part for establishing an electrical connection between a printed circuit board and a terminal of an IC package, comprising:
a socket body to which the IC package is mounted;
a plurality of contact pins provided for the socket body through which a plurality of terminals of the electrical part are electrically connected to the printed circuit board; and
means mounted to the socket body to press the electrical part against the socket body,
each of the contact pins comprising, in a vertical attitude thereof:
a sleeve having an inner space having one end opening;
a plunger inserted into the sleeve through the end opening thereof to be vertically movable; and
an elastic member for urging downward the plunger,
the sleeve being arranged to be vertically movable with respect to the socket body and being provided with a contact portion at an upper end thereof contacting to the terminal of the electrical part to be electrically connected.
In preferred embodiments of this aspect, the means to press the electrical part is a cover member pivotally mounted to the socket body.
The sleeve is composed of a tubular member into which the plunger is fitted and the elastic member is disposed, the elastic member is a coil spring which urges the plunger downward so as to abut against the printed circuit board to establish an electrical connection therebetween.
The socket body has a base on which a plate member is rested, the plate member being formed with a through hole through which the tubular member of the sleeve is inserted.
The tubular portion is formed with an annular protruded portion to an outer periphery thereof
Saijo Takashi
Yamada Takayuki
Enplas Corporation
Nguyen Khiem
Staas & Halsey , LLP
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