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Integration retention and clipping mechanism for BGA mounted CPU and chipset cooling

IP.com Disclosure Number: IPCOM000004733D
Publication Date: 2001-Apr-23
Document File: 3 page(s) / 124K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a design for an integrated retention and clipping mechanism for BGA mounted, unsocketed CPU and chipset or onboard graphics cooling. Benefits include support for larger cooling solutions for high-powered BGA devices, placement of BGA solder balls in a state of compression after assembly, and the transfer of Z (out of board bottom plane direction) dynamic loads to the retention module instead of the BGA balls.

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Integration retention and clipping mechanism for BGA mounted CPU and chipset cooling

Disclosed is a design for an integrated retention and clipping mechanism for BGA mounted, unsocketed CPU and chipset or onboard graphics cooling. Benefits include support for larger cooling solutions for high-powered BGA devices, placement of BGA solder balls in a state of compression after assembly, and the transfer of "-Z" (out of board bottom plane direction) dynamic loads to the retention module instead of the BGA balls.

The disclosed design is an integrated retention solution that provides mounting for both CPU cooling and chipset or onboard graphics. A high-force clip provides high preload on the heat-sinks for improved thermal performance, retains it during "+Z" (out of board top plane direction) direction shock. A combined heat-sink retention module provides lateral load constraints.

The disclosed design addresses the problem of retention of two cooling solutions of BGA unsocketed board-mounted devices in close proximity to one another. This solution is also aimed at putting the top of the motherboard and, therefore, the BGA balls in a compressive state of preload. The BGA balls are compressed after assembly, which is advantageous in preventing ball cracking failure. The design also enables "-Z" direction dynamic loads to be transferred to the retention module and not the BGA solder balls.

Conventionally, small heatsinks have been mounted directly to low-powered BGA devices. This solution does not enable direct BGA attachment due to the cooling requirements and heat-sink mass.

The disclosed design is comprised of the following elements (see Figure 1):

Single-piece unified retention module

Fasteners to hold the retention module to the motherboard

Two heat sinks to cool the GPU and CPU

Two clips to apply a load to the interfaces at the GPU and CPU

The mechanism is assembled by first attaching the retention module to the motherboard via 5 plastic push pin fasteners. Next, the heat sinks are placed within each respective side of the retention module so that the base interfaces with the processor and is cradled by the side walls of the RM. Lastly, each clip is attached to the retention module and interfaced with each heat sink so that it applies a load (see Figure 2). Each clip is keyed so it only assembles to the appropriate heat sink in the appropriate direction. The retention module and clips are made of molded plastic. The heat sinks are constructed by simple extrusion of aluminum with crosscuts in the case of the GPU heat sink.

Fig. 1

Fig. 2

Disclosed anonymously