Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – Distinct contact secured to panel circuit
Reexamination Certificate
2001-12-19
2003-03-18
Bradley, P. Austin (Department: 2833)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
Distinct contact secured to panel circuit
C439S856000, C439S862000
Reexamination Certificate
active
06533591
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for forming fine pitch contacts and fine pitch contacts obtained thereby. Particularly, the present invention relates to a method for forming fine pitch contacts used in a Zero Insertion Force (ZIF) socket and fine pitch contacts used in a ZIF socket.
2. Description of Prior Art
As shown in
FIGS. 4 and 5
, a conventional contact
9
used in a ZIF socket is illustrated. The conventional contact
9
comprises a soldering portion
93
configured as a round plate for being surface-mounted on a printed circuit board through a solder ball attached thereon, a retaining portion
92
extending vertically with respect to the soldering portion
93
and connected thereto through a connecting tab
95
, and a contacting portion
91
for electrically engaging with a pin of a Central Processing Unit (CPU) mounted on the ZIF socket for establishing an electrical connection between the CPU and the printed circuit board. The contacting portion
91
has a neck portion
914
connecting with the retaining portion
92
and a pair of resilient arms
910
projecting oppositely from the neck portion
914
and between which a circular receiving space
913
is defined for receiving the pin of the CPU. The pair of resilient arms
910
have a pair of cantilever contacting fingers
912
defining an engaging gap
911
therebetween.
The conventional contact
9
as described above is formed by the following steps:
a. providing a contact strip with a plurality of contacts stamped thereon (only one stamped contact
9
′ shown in FIG.
5
);
b. curving the horizontal portions
91
′ of the stamped contact
9
′ to form the resilient arms
910
defining a circular receiving space
913
therebetween and the contacting fingers
912
confronting each other;
c. bending the round portion
93
′ of the stamped contact
9
′ to be vertical to the joint portion
92
′ to respectively form the soldering portion
93
and the retaining portion
92
of the final contact
9
; and
d. inserting the plurality of stamped contacts
9
′ in a housing of the ZIF socket and cutting the plurality of stamped contacts
9
′ from the contact strip to obtain the final contacts
9
.
To maintain a fine pitch (which is 1.27 mm as well known in the art) between two adjacent contacts in the ZIF socket, the width “A” of the expanded contacting portion
91
′ stamped on the contact strip should at least double the pitch, that is, at least 2.54 mm. Thus, a problem of the above method for forming the conventional contact is that the expanded contact
9
′ shown in
FIG. 5
wastes a great deal of material.
Furthermore, residual stress is accumulated in the contacting portion
91
when curving the resilient arms
910
of the contacting portion
91
by a bending device.Once the contacting portions
91
of the contacts
9
are removed from the bending device, the pairs of resilient arms
910
will deviate from their intended positions due to stress relaxation. When this happens, the contacting portions
91
of the contacts
9
are unable to accurately mate with the pins of the CPU, thereby adversely affecting a proper engagement between the CPU and the printed circuit board.
Hence, an improved method for forming a contact used in a ZIF socket is required to overcome the above-mentioned disadvantages of the prior art.
BRIEF SUMMARY OF THE INVENTION
A first object of the present invention is to provide a method for forming fine pitch contacts used in a ZIF socket and fine pitch contacts obtained thereby, whereby the space occupied by contacts stamped on a contact strip can be greatly decreased to thus reduce the manufacturing cost of the contacts.
A second object of the present invention is to provide a method for forming fine pitch contacts used in a ZIF socket and fine pitch contacts obtained thereby, whereby the deviation problem of contacting portions of the contacts from their intended positions due to stress relaxation can be effectively solved.
To fulfill the above-mentioned objects, a method for forming fine pitch contacts used in a ZIF socket in accordance with the present invention comprises the following steps:
a. stamping a contact strip comprising a carrier strip and a plurality of contacts, each contact comprising a first portion opposite the carrier strip, a retaining portion extending from the first portion to the carrier strip, and a second portion projecting from the retaining portion and connecting with the carrier strip, the first portion, the retaining portion and the second portion being coplanar with each other, the first portion comprising a pair of arcuate arms defining a circular receiving space therebetween and a pair of parallel contacting fingers extending from respective distal ends of the pair of arcuate arms;
b. bending the first portions of the contacts to form contacting portions perpendicular to the retaining portions and the second portions;
c. bending the second portions of the contacts to form soldering portions perpendicular to the retaining portions and parallel to the contacting portions; and
d. inserting the plurality of contacts in a housing of the ZIF socket and cutting them from the carrier strip.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 5188535 (1993-02-01), Bertho et al.
Bradley P. Austin
Chung Wei Te
Gilman Alexander
Hon Hai - Precision Ind. Co., Ltd.
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