Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – With provision to conduct electricity from panel circuit to...
Reexamination Certificate
2003-03-31
2004-06-22
Gushi, Ross (Department: 2833)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
With provision to conduct electricity from panel circuit to...
C439S721000
Reexamination Certificate
active
06752635
ABSTRACT:
BACKGROUND
1. Field
Embodiments of the present invention relate to sockets for coupling integrated circuits to printed circuit boards, and in particular to land grid array (LGA) sockets having separate geometries for power delivery and signal contacts.
2. Discussion of Related Art
A land grid array (LGA) socket is a common connector used to couple an integrated circuit (IC) package to a printed circuit board (PCB.
FIGS. 1A through 1E
show an exploded view of a typical known LGA IC package-socket-PCB assembly
100
.
FIG. 1A
shows a printed circuit board (PCB)
102
,
FIG. 1B
shows the top side (
1
C package side) of an LGA socket body
104
. LGA contacts
106
shown in
FIG. 1C
fit into the socket body
104
.
FIG. 1D
shows the IC package
108
as viewed from above as though looking through the IC package
108
.
FIG. 1E
shows details of a portion
110
of the PCB
102
. The socket assembly (i.e., the socket body
104
with the contacts
106
inserted), which is shown as a bottom view, is soldered to the PCB
102
, which is shown as a top view. The IC package
108
mounts to the top side of the socket body
104
.
The contacts
106
fit into slots
112
on the socket
104
. Each contact
106
has a contact pad
114
that is soldered to a corresponding solder pad
116
on the PCB
102
. Each contact
106
also has a contact pin
118
that mates to corresponding lands
109
on the IC package
108
.
The PCB
102
has a signal delivery area
120
and a power delivery area
122
. The socket body
104
has a signal delivery area
124
and a power delivery area
126
. The IC package
108
has a signal delivery
128
area and a power delivery area
130
. Each of the signal delivery areas corresponds to the other signal delivery areas such that input/output (I/O) signals (such as data and address signals) coming from signal planes in the PCB are electrically coupled to the appropriate solder pad
116
, contact
106
, and socket body
104
land. Likewise, each of the power delivery areas corresponds to the other power delivery areas such that power (V
CC
) and ground (V
SS
) coming from power and ground planes in the PCB
102
are electrically coupled to the appropriate solder pad
116
, contact
106
, and socket body
104
land.
One characteristic of the conventional LGA IC package-socket-PCB assembly
100
is that the contact design in the power delivery areas is the same the contact design in the signal areas (i.e., the contact
106
). The contacts in the power delivery areas do not have the same function as the contacts in the signal areas, however. For example, the contacts in the power delivery areas carry high currents and the contacts in the signal areas carry low currents. Increased current density through the contacts
106
positioned in the power delivery area
126
may create self-heating which may increase contact
106
resistance and limit power delivery to the IC package
108
. As high performance components consume more power and current, electrical resistance of the contacts
106
may limit power delivery to such components.
An existing approach to reducing current density through the contacts
106
is to allocate more contacts
106
in the LGA IC package-socket-PCB assembly
100
for power delivery, i.e., increase the size of the power delivery area
126
. Increasing the size of the power delivery area
126
reduces the size of the signal delivery area
126
, however, which may mean that the number of contacts
106
available for signals is reduced.
Another existing approach is to add more contacts
106
to the assembly
100
. More contacts
106
means that the socket assembly is larger, however, and that the IC package
108
is larger. Additionally, more contacts
106
generally requires greater IC package to socket insertion force in order to maintain an effective IC package to socket interface resistance. This greater insertion force can further complicate effective enabling design.
Another characteristic of the conventional LGA IC-socket-PCB assembly
100
is that the body of the socket
104
is made from injection-molded plastic and each slot
112
is injection molded. This introduces limitations on contact
106
spacing, which can also introduces limitations on PCB solder pad
116
spacing and IC package land
109
spacing. Also, if more pins are to be added, the individual parts of the LGA IC package-socket-PCB assembly
100
are more expensive.
The socket assembly portion
110
illustrates this point. The portion
110
includes channels
132
. The channel
132
has a length
134
and a set of slots
112
, lands
109
, contacts
106
, and solder pads
116
. The channel
132
has a length of approximately 10.16 mm or more. Within that length the channel
132
has approximately eight to nine slots
112
, lands
109
, contacts
106
, and solder pads
116
. Also within that length the channel
132
has a pitch (e.g., slot
112
-to-slot
112
, land
109
-to-land
109
, and contact
106
-to-contact
106
) of approximately one millimeter (mm). Because of the slots
112
are injection molded individually, the LGA IC package-socket-PCB assembly
100
is so limited.
REFERENCES:
patent: 5624280 (1997-04-01), Kato
patent: 5683256 (1997-11-01), Werther
patent: 6328574 (2001-12-01), Howell et al.
patent: 6383035 (2002-05-01), Kasai
patent: 6390827 (2002-05-01), Howell et al.
patent: 6575766 (2003-06-01), Xie et al.
Manik Jiteender P.
Ruttan Thomas G.
Searls Damion T.
Blakely , Sokoloff, Taylor & Zafman LLP
Gushi Ross
Intel Corporation
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