Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – With provision to conduct electricity from panel circuit to...
Reexamination Certificate
2002-09-12
2004-11-09
Paumen, Gary (Department: 2833)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
With provision to conduct electricity from panel circuit to...
C439S062000
Reexamination Certificate
active
06814583
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to printed circuit board (PCB) connectors, and more particularly to high performance PCB edge connectors, systems and methods.
The use of electronics has become ubiquitous, finding its way into all manners and shapes of devices and appliances ranging from toasters to super-computers. Most electronic circuitry is now implemented with their active and passive devices coupled together by a printed circuit board (PCB). This is true whether the electronic circuitry being implemented is primarily analog in nature, digital in nature, or a hybrid of the two.
In its simplest form, a PCB is a relatively thin sheet of a dielectric (i.e. electrically non-conductive) material such as a resin-filled fiberglass. Metal lines or “traces” are typically formed on one or more surfaces of the fiberglass to provide electrical connections between the various components of the electronic circuit.
Printed circuit boards can be “one sided,” in which all of the traces are formed on one side of the dielectric sheet of material. PCBs can also be “two sided,” where traces are formed on both sides of the sheet of dielectric material. Furthermore, PCBs can be “multi-layer” where multiple dielectric layers are sandwiched between conductive layers, which may form traces or which may form grounds and/or power planes. With multi-layer boards it is common to provide electrical connections between various layers by the formation of “vias” (conductive plugs between metal layers) or through-holes through which conductors can be threaded.
Commonly, an electronic circuit implemented on a PCB is connected to other devices. These may be input/output devices, other electronic circuits supported on other PCBs, transmission lines, etc. While such devices could be connected directly to the PCB (such as being soldered to some of its traces or bonding pads), most commonly the connection to external devices or circuits is through a removable connector assembly. Electrical connectors of various types have been developed through the years for just this purpose.
FIGS. 1 and 2
illustrate a connection system of the prior art. This particular connection system is known as a single connector attachment or “SCA” and was primarily designed to replace the older Small Computer System Interface or “SCSI” connector design, which was not designed for modern high-frequency digital circuit operation.
In
FIG. 1
, a PCB
10
including traces,
12
formed on a dielectric body
14
has a male SCA connector
16
attached to its upper surface
18
. The male connector
16
includes a support
20
having a number of electrical contacts
22
and a surrounding shroud
24
. The SCA male connector
16
is also provided with a pair of alignment posts
26
a
and
26
b.
In
FIG. 2
, a PCB
28
provided with traces
30
on a dielectric substrate
32
includes a female SCA connector
34
. The female connector includes a slot
36
provided with a plurality of contacts
38
. The slot
36
is receptive to the support
20
such that when the support
20
engages with the slot
36
the contacts
22
of the male connector
16
engage with the contacts
38
of the female connector
34
. The shroud
24
of the male connector
16
surrounds the body
40
of the female connector
34
. The male connector
16
is guided into and locked in place with the female connector
34
by the alignment post
26
a
and
26
b
aligning with and engaging the alignment columns
42
a
and
42
b
of the female connector
34
.
The contacts
22
are in electrical contact with some of the traces
12
of the printed circuit board
10
. This can be accomplished with a surface mount technology (SMT) if the traces are formed on the same side of the printed circuit board as the male connector
16
, or with pin-through technology if the traces
12
are formed on the opposite side of the PCB
10
from the connector
16
. In the present example, a surface mount technology is illustrated. Likewise, the electrical contacts
38
connect to certain ones of the traces
30
at printed circuit board
28
. Thus, when the male connector
16
is engaged with the female connector
34
, the printed circuit boards
10
and
28
are in electrical communication.
It should be noted that while the SCA connectors are shown to be attached to two different PCB boards, one of the SCA connectors, such as the male SCA connector
16
, could, instead, be coupled to a cable, such as a ribbon cable. In this fashion, the SCA connector can be used to couple physically separated electronic devices.
Two-piece connectors such as the SCA connectors illustrated in
FIGS. 1 and 2
have several advantages. For one, they are mechanically guided and secured which aids in the engagement and the retention of the engagement of the connector system. For another, since they are typically made from metal, they are well-shielded by, for example, the body of their connectors and by the shroud
24
of the male connector. This helps reduce electromagnetic radiation and, therefore, electromagnetic interference (EMI). However, these connectors suffer from a number of drawbacks including cost, size, and an impedance matching problems generated by the wide separation between the ground planes of the two electronic circuits being coupled together caused by the connectors.
Another connection technology of the prior art is illustrated in FIG.
3
. In this figure, a first PCB or “plug-in board”
44
includes a male edge connector portion
46
. This edge connector
46
is simply a portion of the PCB with a number of traces
48
that serve as contacts with contacts of a female edge connector. In this particular illustrated example, the edge connector has a first portion
50
and a second portion
52
separated by a slot
54
. There are also unslotted variants of edge connectors in the prior art.
The female edge connector
56
is preferably coupled to a PCB
58
having traces on its bottom surface
60
(not shown), traces can also be located on a top surface
59
of PCB
58
. Pins
62
of the female edge connector
56
extend through holes
64
drilled through the printed circuit board
58
and are soldered to traces or bonding pads at the end of traces on the bottom surface
60
. The female edge connector
56
is provided with a pair of slots
66
and
68
including a number of contacts
70
which couple to the pins
62
.
In operation, the first portion
50
of the male edge connector
46
engages the slot
66
of the female edge connector
56
, and the second portion
52
of the male edge connector
46
engages with the slot
68
of female edge connector
56
. In this way, the traces
48
of plug-in board
44
are in electrical contact with the contacts
70
and, therefore, the traces (not shown) of PCB
58
.
The edge connector technology illustrated in
FIG. 3
has certain advantages, including the elimination of a separate male connector. This not only reduces cost, but it also brings the ground planes of the two PCBs closer together, which can be advantageous, particularly in high frequency applications. However, the ground planes are still separated by the body of the female edge connector
56
, thus reducing high-frequency performance.
An ever-increasing percentage of electronic circuitry is at least partially digital in nature. Furthermore, digital circuitry is operating at ever higher frequencies. For example, at the dawn of the computer age electronic circuitry was operating in the megahertz frequency range, while now it is not uncommon for circuitry to operate in the gigahertz and above frequency range. The operation of electronic circuitry at high frequencies creates a whole host of problems including EMI, cross coupling, data integrity, losses, reflections, etc.
One way of addressing the special needs of high frequency electronic circuit operation is the use of differential pairs to carry high frequency digital data. Differential pairs are typically labeled plus (+) or minus (−) where the plus line is used to carry the charge comprising the signal to the intended desti
Kelley Michael C.
Kim Joung-ho
Young J. Pat
Paumen Gary
Perkins Coie LLP
Silicon Image Inc.
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