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Method for using a vacuum seal to mechanically couple a chassis to a motherboard

IP.com Disclosure Number: IPCOM000008969D
Publication Date: 2002-Jul-26
Document File: 7 page(s) / 153K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for using a vacuum seal to mechanically couple a chassis to a motherboard. Benefits include improved reliability.

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Method for using a vacuum seal to mechanically couple a chassis to a motherboard

Disclosed is a method for using a vacuum seal to mechanically couple a chassis to a motherboard. Benefits include improved reliability.

Background

              As processors on motherboards continue to increase in speed and power, the mass of the CPU heatsink continues to increase. The heatsink for one advanced processor reached 450g. With this mass on a typical ATX motherboard architecture, the BGA to board interconnect of the chipset next to the CPU is being damaged from shock and vibration due to severe board flex caused by mass of the CPU sink.

              To mitigate damage to the chipset interconnect, a structural reinforcement solution must be implemented to protect the chipset. The task is complicated by the fact that the CPU/chipset core is the area with the highest trace density. Dedicating keep outs (component or trace) to a mechanical solution typically causes the board layer count to increase, which effectively prices the motherboard out of the competitive market.

              Conventionally, a popular drop-in mechanical stiffening solution for motherboards in the marketplace is the addition of wave-soldered stiffening bars (see Figure 1). They are essentially small I-beams that are wave soldered to the board by holes at regular intervals. These bars are placed at strategic locations and orientations on the board to reduce deflection in selected directions. The stiffening bars, however, drastically change and constrain component placement on a motherboard. In addition, the holes required are large. In the typical desktop motherboard architecture, stiffening bars are not feasible. They are mainly used in workstation and server segments that already have high layer count boards.

              Stiffening plates and load transfer plates are common. These solutions attach a plastic or metal plate to the backside of the motherboard in the CPU/chipset core area. They are typically attached to the motherboard by rivets that require large holes and are difficult to accommodate. Both solutions require access to the backside of the motherboard and a back-side assembly step during manufacturing. Back-side assembly is not a process that typically occurs in desktop motherboard manufacturing and can lead to increased assembly cost, depending on assembly line design. Stiffening plates typically have sufficient stiffness to reinforce the motherboard.

              Load transfer plates are designed to capture the motherboard and lock to a point in the chassis. These plates use the metal chassis as a source of mechanical stiffening. Load transfer plates have an additional limitation in that motherboard design and chassis design must be coordinated and tooled. Load transfer plates are typically only an option for systems OEMs that control the design of their own boards and chassis.


General description

              The disclosed method uses an airtight seal to mechanically couple the computer chassis pan to the motherboard. A sealed air volume betw...