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Method for a surface-mount solder apparatus for reducing ESR and ESL in PGA sockets

IP.com Disclosure Number: IPCOM000008971D
Publication Date: 2002-Jul-26
Document File: 6 page(s) / 247K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a surface-mount solder apparatus for reducing equivalent series resistance (ESR) and equivalent series inductance (ESL) in PGA sockets. Benefits include improved power performance, improved resistance and inductance, and improved use of silicon surface area.

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Method for a surface-mount solder apparatus for reducing ESR and ESL in PGA sockets

Disclosed is a method for a surface-mount solder apparatus for reducing equivalent series resistance (ESR) and equivalent series inductance (ESL) in PGA sockets. Benefits include improved power performance, improved resistance and inductance, and improved use of silicon surface area.

Background

              Requirements on power delivery have increased to achieve higher performance in logic silicon products. Higher current-carrying capability is frequently a key parameter sought in successful power-delivery design. One potential bottleneck is the delivery of power through the motherboard and socket interface. Conventionally, the same interconnect structure is used for both the power and signal connection even though the requirements from power and signaling can be different.

              On conventional high-power sockets, the power/ground connections and the I/O connections are made through copies of the same structure. These structures are not optimized for current delivery to the part and take up valuable silicon surface area.In general, power and signaling have different key parameters. Power parameters include high current and relatively low frequency. Signaling parameters include low current and high frequency.

              For example, the same structure is used repeatedly for component/socket/PCB interconnection (see Figure 1). The relatively low-volume connection can limit current to the component. Better power delivery can often lead to more power/ground solder balls that can lead to excessively large packages and sockets. In addition, these power connections compete with much-needed I/O connections on the component.

Description

              The disclosed method is surface-mount solder apparatus that uses surface-mount technology (SMT) and socket structures to separate and optimize power delivery to the component. For example, to optimize through-socket power delivery, the individual power delivery contacts are replaced by a multipin contact metal structure (see Figure 2). This structure simultaneously contacts two or more pins on the same net. This structure is soldered to the board using a solder bar. Rectangular metal pads replace individual solder pads on the main board. These features increase the mass of current-conduction material within the same space as the typical solution.

              A top-down view of a socket interconnect shows the basic footprint made by the socket pin-contact and solder ball (see Figure 3). In addition, the figure illustrates the conversion of typical structures to a ganged structure. Although the total area taken by the interconnects is the same, the ganged PGA concept takes up a greater proportion of the area. For the dimensions shown, the interconnect area increase is roughly 100% for the solder and 50% for the contact structure. Resistance, R, is inversely proportional to the area, A:

              The resistance decreases by ~33% due to the contact. The solder decreases by ~50%. The packa...