Patent Application
20050133901
The present invention relates generally to semiconductor devices and, more particularly, to a system and method for delivering power to a semiconductor device.
The size of integrated circuit packages have grown in recent years. Increasing the size of package substrates results in levels of substrate warping which are unacceptable. Warping causes problems with the installation and retainment of the package on the motherboard. Such problems can lead to failure and disposal of the motherboards, which can be very expensive. In addition, delivery of power and ground to the substrate through the motherboard has become problematic due to the large number of power and ground connections required by the package substrate.
The present invention provides a system and method for delivering power to a semiconductor device that substantially eliminates or reduces at least some of the disadvantages and problems associated with previous systems and methods.
In accordance with a particular embodiment of the present invention, a system for delivering power to a semiconductor device includes a package substrate comprising a substrate top surface and a substrate bottom surface. The system includes a connector formed on the substrate top surface and a cable coupled to the connector. The cable is operable to deliver power and ground to a top of the package substrate.
The cable may be further operable to deliver input/output (I/O) to the top of the package substrate. The cable may comprise a single metal layer or multi-metal-layer polyimide cable or a ribbon cable. The cable may be formed on the substrate top surface using a solder reflow process. The system may also include at least one additional connector formed on the substrate top surface and at least one additional cable coupled to the at least one additional connector. The at least one additional cable may be operable to deliver power to the top of the package substrate.
In accordance with another embodiment, a method for delivering power to a semiconductor device includes forming a connector on a substrate top surface of a package substrate and coupling the package substrate to a printed circuit board. The method includes coupling a cable to the connector and delivering power and ground to a top of the package substrate through the cable. Forming a connector on the substrate top surface may comprise forming a connector on the substrate top surface using a solder reflow process in the semiconductor device manufacturing process.
In accordance with yet another embodiment, a printed circuit board comprises a plurality of package substrates formed upon the printed circuit board. Each package substrate comprises a substrate top surface. The printed circuit board includes a plurality of connectors formed directly upon each substrate top surface and a cable coupled to each connector. Each cable is operable to deliver power and ground to a top of at least one of the plurality of package substrates. The printed circuit board may further comprise a power regulation module coupled to at least one of the cables. The power regulation module may be operable to regulate the power delivered to the top of at least one of the plurality of package substrates.
Technical advantages of particular embodiments of the present invention include a connector merged with a package substrate so that a cable coupled with the connector may be used to deliver power, ground and I/O to the top of the package substrate. Thus, a manufacturer may be able to reduce the number of power and ground layers formed in the printed circuit board. Accordingly, the cost and labor of manufacturing the printed circuit board may be reduced. Moreover, the conducting metal in the cable may be thicker than the metal in the power and ground layers of the printed circuit board, thus increasing the efficiency of the conducting metal used to deliver power and ground to the package substrate. Moreover, use of power and ground connections on the top surface of the substrate results in a concomitant reduction in required number of terminals on the bottom of the substrate, allowing a reduction in the substrate size.
Other technical advantages will be readily apparent to one skilled in the art from the following figures, descriptions and claims. Moreover, while specific advantages have been enumerated above, various embodiments may include all, some or none of the enumerated advantages.
For a more complete understanding of particular embodiments of the invention and their advantages, reference is now made to the following descriptions, taken in conjunction with the accompanying drawings, in which:
A surface mount connector 18, such as a low inductance connector, is formed onto package substrate 14. In particular embodiments connector 18 may be merged with package substrate 14 using a solder reflow process. Using a solder reflow process to merge connector 18 directly with package substrate 14 enables the connector to be formed on package substrate 14 during the normal manufacturing process of package substrate 14. For example, package substrate 14 may be put through a furnace in order to include components such as chip capacitors with a substrate, and such furnace process may be utilized to merge connector 18 with package substrate 14.
The formation of connector 18 upon package substrate 14 enables power, ground and I/O to be brought directly into package substrate 14 through a cable 20. In particular embodiments, cable 20 may comprise a flex cable, such as a low inductance ribbon cable, or a single or multi-layer polyimide cable. Other embodiments may include other types of cables for bringing power, ground and/or I/O to package substrate 14 through connector 18. In some embodiments, cable 20 may include bypass capacitors so that power regulation and filtering may be performed through the cable. Capacitors may be distributed along the top of the cable to enable decoupling of noise from power and ground planes of the cable.
In particular embodiments, the power and ground brought directly to package substrate 14 through cable 20 may comprise core power and ground. Such core power and ground supplies the circuitry for the die. In some embodiments, core power and ground may comprise approximately 15% to 40% of the total power and ground current of the package.
The ability to supply power, ground and I/O to the top of package substrate 14 through cable 20 may enable a manufacturer to reduce the number of power and ground layers formed in the printed circuit board. Thus, the cost and labor of manufacturing the printed circuit board may be reduced. Moreover, the conducting metal in the cable may be thicker than the metal in the power and ground layers of the printed circuit board, thus increasing the efficiency of the conducting metal. For example, metal in the printed circuit board may have a thickness of approximately 12 microns, while metal in a polyimide cable may have a thickness of approximately 25 microns. A ribbon cable may include metal having a thickness of approximately 500 microns.
At step 104, a cable is coupled to the connector. The cable may comprise a single or multi-layer polyimide cable. In some embodiments, the cable may comprise a flex cable or a ribbon cable. At step 106, power and ground is delivered to the top of the package substrate through the cable. At step 108, I/O is delivered to the top of the package substrate through the cable.
Some of the steps illustrated in
Although the present invention has been described in detail with reference to particular embodiments, it should be understood that various other changes, substitutions, and alterations may be made hereto without departing from the spirit and scope of the present invention. For example, although the present invention has been described with reference to a number of elements formed upon a printed circuit board and a package substrate, it should be understood that printed circuit boards and package substrates in accordance with particular embodiments may include other elements in order to accommodate particular needs. The present invention contemplates great flexibility in the arrangement of these elements as well as their internal components.
Numerous other changes, substitutions, variations, alterations and modifications may be ascertained by those skilled in the art and it is intended that the present invention encompass all such changes, substitutions, variations, alterations and modifications as falling within the spirit and scope of the appended claims. Moreover, the present invention is not intended to be limited in any way by any statement in the specification that is not otherwise reflected in the claims.
