Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – With contact or lead
Reexamination Certificate
2002-04-17
2004-01-20
Clark, Sheila V. (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
With contact or lead
C257S773000, C257S727000
Reexamination Certificate
active
06680526
ABSTRACT:
FIELD OF THE INVENTION
Embodiments of the present invention pertain to sockets with contacts that connect to a microelectronic device package, and more particularly, to a socket with low inductance side contacts.
BACKGROUND
In microelectronic device manufacturing, a microelectronic device is formed on a semiconductor chip, or “die”. The die is commonly mounted to a “package”, which serves to protect the die and may also provide a standardized interface between the die and the printed circuit board (PCB) on which it will be used. The package, with the die mounted on it, is often coupled to the PCB by a socket mounted on the PCB.
An important issue associated with microelectronic systems is high-current power delivery for high speed products. With existing technology, the ability to provide high currents and low inductance for high speed products generally is accomplished by increasing the pin count, i.e., the number of electrical contacts of the microelectronic device. The term “pin” is used herein for convenience to refer to any type of electrical contact of a microelectronic device, such as a pin, solder ball, etc. High pin counts unfortunately tend to increase cost, since cost is related to the number of pins, socket size, and package size, among other factors. Also, with package sizes being driven smaller and smaller, such as for mobile applications, it is becoming increasingly more important to reduce (or at least not to unnecessarily increase) pin counts.
FIGS. 1A and 1B
show in cross-section an example of how a package
1
, to which a microelectronic die
2
is mounted, can be connected to a socket
3
on a circuit board (e.g., a PCB)
4
. The illustrated configuration provides a low resistance connection to shunt power from the side of the package
1
to the circuit board
4
. However, with this configuration, a large number of pins are still required to maintain a low inductance connection. Hence, it is possible to deliver higher current, but power for higher speed products still requires the same number of pins.
Another issue associated with high speed products is the signal-to-reference ratio. The signal-to-reference ratio is the ratio of the number of signal pins to the number of reference pins of the device. Generally, in high speed applications it is desirable to maintain a low signal-to-reference ratio. A low signal-to-reference ratio tends to limit routability, but high signal-to-reference ratios of high speed signals tend to cause poor signal integrity. To design a socket for higher speeds, therefore, requires a low signal-to reference ratio. However, with existing technology, lowering the signal-to reference ratio normally requires increasing the pin count to provide more reference pins. The disadvantages of higher pin counts are noted above.
REFERENCES:
patent: 5400220 (1995-03-01), Swamy
patent: 5751553 (1998-05-01), Clayton et al.
patent: 6390827 (2002-05-01), Howell et al.
Figueroa David G.
Li Yuan-Liang
Blakely , Sokoloff, Taylor & Zafman LLP
Clark Sheila V.
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