Browse Prior Art Database

Method for an injection molded IHS with integrated micro-channels for attachment to an external cooling device

IP.com Disclosure Number: IPCOM000007143D
Publication Date: 2002-Feb-27
Document File: 7 page(s) / 801K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for an injection molded integrated heat spreader (IHS) with integrated micro-channels for attachment to an external cooling device. Benefits include improved thermal performance and improved reliability.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 45% of the total text.

Method for an injection molded IHS with integrated micro-channels for attachment to an external cooling device

Disclosed is a method for an injection molded integrated heat spreader (IHS) with integrated micro-channels for attachment to an external cooling device. Benefits include improved thermal performance and improved reliability.

Background

      The conventional method is simply a flat polished piece of silicon. A separate, typically flat on top and bottom, IHS is attached to the polished die using a thermal interface material (TIM). A separate heatsink is applied to the top of the IHS, typically with thermal grease assuring contact. The heatsink is held in place with mechanical clips. A fan is optionally added to increase the air circulation around and through the heatsink (see Figure 1).

      Micro-channels dissipate heat from a microprocessor die and evaporate water to vapor. These advantages are fully realized only if the micro-channels are made in the die itself and TIM is removed between the die and the micro-channel. However, micro-channels in the die itself introduces some adversities, including:

•             Mechanical weakness

•             Change in the fabrication process

•             Water (best fluid for room temperature electronics) directly contacts the die

      These issues pose technical and financial challenges. With the conventional solution, the mutual contact surfaces of the die and the IHS are polished flat. The IHS and the die are bonded together by the TIM. Heat generated from the die conducts through silicon, across the flat contact surface where there is a TIM coating between the die and the IHS. It spreads the heat over a greater surface area and enables conduction of the heat into the heatsink. The interface between the IHS and heatsink is made more efficient by utilizing a thermal grease-type material.

Description

              The disclosed method forms micro-channels in an injection-molded polymer as an IHS (see Figures 2 through 5). The polymer used is typically liquid crystal polymer (LCP) that is carbon-doped to increase thermal conductivity. The IHS is a passive thermal transfer device that incorporates coolant channels, which are later connected to an external heat-transfer/cooling device. When molded, a separate cap seals the cooling channels, prevents leakage of the cooling media and contains the connecting surfaces for attaching to the cooling system. The cap is placed on the molded thermal transfer device. At final assembly, its intake and exhaust manifolds are connected to an external cooling system that circulates a thermal fluid through the micro-channel to absorb heat energy. The heat is then dissipated through the external cooling device.

              The key element of the method is injection molding a liquid crystal polymer doped with carbon to increase its thermal conductivity, creating an integrated heat spreader with micro-channels through which thermal fluid can be circulated.

Advantages

              The disclosed method provides several advantages, including:

•             Improved he...