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Method for shape-memory alloy jet impingement flow control

IP.com Disclosure Number: IPCOM000008066D
Publication Date: 2002-May-15
Document File: 3 page(s) / 24K

Publishing Venue

The IP.com Prior Art Database


Disclosed is a method for shape-memory alloy (SMA) jet impingement flow control. Benefits include improved thermal performance and improved reliability.

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Method for shape-memory alloy jet impingement flow control

Disclosed is a method for shape-memory alloy (SMA) jet impingement flow control. Benefits include improved thermal performance and improved reliability.


              Conventionally, no active feedback control is used to manage die cooling. Localized heat fluxes over the floating point can occur on the order of 350 W/cm2 with a localized temperature as high as 130oC. Conventionally, heat is dissipated away from the chip when the heat has diffused to the surface of the processor. As processor performance continues to increase so does the heat generation within the processor. The problem of localized heating has not been attacked from the vantage point of controlling the local die temperature by regulating impingement flow for cooling the die. Only cooling methods external to the processor have been implemented to date.

              SMA technology uses nickel-titanium (NiTi) or brass alloys.

General description

              The disclosed method is impingement cooling for cooling processor hot spots. Jet orifices are opened and closed using SMA technology that expands when heated above its martensite temperature and contracts when cooled. The heat convected and conducted from the die surface is used to heat the SMA. When the SMA reaches its martensite temperature, it expands. The expansion process can be used to push open a stopper, enabling fluid to flow (impinge) on the surface of the die. As the die cools, the heating of the SMA occurs at a lower temperature, cooling the SMA. As it cools, it contracts, closing the stopper and ending the subsequent fluid flow. The closed-loop fluid system consists of the following items:

§         Reservoir

§         Plenum with an array of jet orifices

§         Pump

§         SMA wires

              The key elements of the method include:

§         Use of shape memory alloys to open and close an array of stoppers used to regulate the flow of a cooling fluid for die thermal control

§         Use of a plenum to store fluid for immediate use.

§         Use of convected and conducted heat from the surface of the processor for regulating jet opening and closing

§         Use of shape memory alloy (SMA) and the attribute of reversible expansion/contraction for moving the stopper

§         Manufacturing at either the microscopic level using conventional fabrication technology or the macroscopic level using micro-electromechanical systems (MEMS) manufacturing technology.


              The disclosed method provides advantages, including:

§         Improved thermal performance by using impingement cooling and spreading the heat more uniformly within the die

§         Improved processor reliability due to improved thermal performance

§         Localized cooling that is accomplished without the need for temperature sensors on the die (taking up valuable silicon surface area) to control the...