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3D Chip Stack Packaging Enclosures

IP.com Disclosure Number: IPCOM000244157D
Publication Date: 2015-Nov-16
Document File: 6 page(s) / 165K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed are methods to effectively cool 3D chip stacks.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 52% of the total text.

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3 3D Chip Stack Packaging Enclosures D Chip Stack Packaging Enclosures

The problem that is solved with this invention is effectively cooling 3D chip stacks. Known solutions include applying a thermal grease, oil, or soft metal to the backside of the top chip (shown in Figures 1 and 2 below) or the top of a lid. This is an inadequate technique for
a stack structure with many chips or a chip stack having a high-power chip on the bottom or middle of the stack.

Figure 1

Figure 2

    Other known solutions include cooling the device through the use of fluidic micro-channels or by flowing an electrically inert fluid over the device. In both cases, a fluid

1


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chamber, recirculation motor, and/or a cooling apparatus are needed to provide adequate cooling. These methods are expensive and can take up large amounts of space in a server rack. This disclosure is aimed at efficiently cooling 3D chip stacks.

Embodiment 1: A lid for a 3D chip stack that has integrated heat sink fins on its top surface. By integrating heat sink fins directly onto the lid, the heat transfer interfaces are reduced as the need for an additional TIM2 material and a heat sink is eliminated, resulting in a higher performing cooling solution in a smaller package.

Embodiment 2: An enclosure for a 3D chip stack that allows for TIM material to encase the 3D chip stack to promote heat dissipation vertically and horizontally. This is advantageous over the known methods above because the heat is conducted away from the chips stack in every direction instead of only in the vertical direction. By allowing the heat to dissipate in multiple directions, the cooling efficiency of the TIM material will be increased, resulting in a smaller heat sink needed to achieve the same thermal performance as traditional methods. An additional benefit is that if TIM material can be in direct contact with the lower chips, which typically only utilize the conductive underfill for heat transfer. By providing direct contact with the TIM to all chips, a more uniform heat distribution will be created and the problematic chips near the substrate/interposer will run cooler.

    Sub-embodiment of 2_1 : An enclosure for the 3D chip stack module that has integrated heat sink fins on the edges of the enclosure to promote heat dissipation horizontally. By incorporating heat sink fins onto the enclosure edges, heat dissipation via fins will be maximized.

    Sub-embodiment of 2_2 : The 3D chip stack is cooled by submerging the 3D chip stack into liquid metal. This method is advantageous because the device would operate at lower temperatures compared to devices utilizing traditional TIM1 materials due to the high ther...