Electrical connectors – With coupling movement-actuating means or retaining means in... – Including compound movement of coupling part
Reexamination Certificate
2003-01-14
2004-02-17
Paumen, Gary (Department: 2833)
Electrical connectors
With coupling movement-actuating means or retaining means in...
Including compound movement of coupling part
Reexamination Certificate
active
06692282
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a zero insertion force (ZIF) socket for electrically connecting an electronic package such as a ball grid array (BGA) chip with a circuit substrate such as a printed circuit board (PCB), and particularly to a ZIF socket having a uniformly flat cover.
2. Description of the Prior Art
Electrical sockets are widely used in the connector industry for electrically connecting central processing units (CPUs) to printed circuit boards (PCBs) in personal computers (PCs). This is detailed in “Development of ZIF BGA SOCKET” (Connector Specifier, February 2002, pp. 18-20), and in U.S. Pat. Nos. 5,722,848 and 5,855,489. Referring to
FIG. 4
, the electrical socket
6
is designed for electrically interconnecting a CPU (not shown) with a PCB (not shown). The electrical socket
6
mainly comprises a dielectric base
60
having a multiplicity of terminals
63
received therein, a cover
61
slidably mounted on the base
60
, and an actuation device
62
engaged with the base
60
and the cover
61
. The CPU is attached and seated on the cover
61
, with the pins of the CPU extending through the cover
61
. By turning the actuation device
62
, the cover
61
moves along the base
60
between an open position and a closed position. The CPU and the PCB are electrically connected in the closed position, and disconnected in the open position. The base
60
comprises a widened front portion
600
adjoining a main portion
601
. The main portion
601
defines a multiplicity of terminal passageways
6010
in a generally rectangular array, the passageways
6010
interferentially receiving corresponding terminals
63
. The cover
61
comprises a raised portion
610
at an end thereof, corresponding to the front portion
600
of the base
60
. A multiplicity of holes
611
is defined in the cover
61
, corresponding to the passageways
6010
of the base
60
.
The cover
61
is integrally formed by injection molding. Forming the cover
61
to have the raised portion
610
is problematic. When flowing molten raw material is injected into a mold from a gate of the mold to form the cover
61
, the flowing molten raw material is fed from a material source to a cavity in the mold through a runner system. Because the raised portion
610
is thicker than a main portion of the cover
61
, the raised portion
610
of the cover
61
cools at a different rate from that of the main portion. Fibers gradually formed inside the material of the raised portion
610
and inside the material the main portion are arranged differently. This results in different and undesired internal stresses in these portions of the cover
61
. These stresses usually cause the main portion and the raised portion to become deformed or deflected. The main portion of the cover
61
is not uniformly flat, and engagement between the base
10
and the cover
11
is incomplete and unreliable. Accordingly, mechanical and electrical connection between the CPU and the socket
6
may be impaired.
Therefore, a new electrical socket which overcomes the above-mentioned problems is desired.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a ZIF socket having a cover configured to minimize the risk of distortion of the cover during molding thereof.
Another object of the present invention is to provide a ZIF socket having an inexpensive cover.
To achieve the above objects, a ZIF socket of the present invention is for electrically connecting a central processing unit (CPU) with a printed circuit board (PCB). The socket includes a dielectric base, a cover slidably mounted on the base, an actuator rotatably mounted between the base and the cover, and a multiplicity of terminals received in the base for electrically connecting pins of the CPU with the PCB. The cover comprises a main supporting portion, and a raised portion formed at one side of the supporting portion. The cover defines a multiplicity of holes therein, for receiving the pins of the CPU therethrough. A plurality of blind cavities is defined in a face of the cover that abuts the base. A cross section of each blind cavity is round.
The cover is formed as a single piece by molding. During cooling down of the duly molded cover, fibers gradually formed inside a material of the cover can be arranged randomly relative to a lengthwise axis of the cover. In addition, the material of the cover can be cooled down quickly without producing undesired stress inside the cover. This reduces the risk of deformation of the supporting portion of the cover. Tests have shown that the blind cavities can reduce deformation of the cover by up to 0.1 mm, thus significantly enhancing uniform flatness of the cover. This helps ensure that engagement between the base and the cover is accurate and reliable.
REFERENCES:
patent: 6254415 (2001-07-01), Mizumura et al.
patent: 6296506 (2001-10-01), Mizumura et al.
patent: 6338640 (2002-01-01), Lin
patent: 6340309 (2002-01-01), Lin et al.
patent: 6431900 (2002-08-01), Yu
patent: 6450827 (2002-09-01), Huang et al.
patent: 6464525 (2002-10-01), Mizumura
patent: 6475013 (2002-11-01), Pang et al.
patent: 6500019 (2002-12-01), Tan
patent: 6508659 (2003-01-01), Howell et al.
Sun XuDong
Ye Pengfei
Chung Wei Te
Harvey James R.
Paumen Gary
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