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Highly Parallel Flow to Reduce Hydraulic Resistance of Heat Exchangers

IP.com Disclosure Number: IPCOM000110367D
Original Publication Date: 1992-Nov-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 4 page(s) / 192K

Publishing Venue

IBM

Related People

Zingher, AK: AUTHOR

Abstract

A technique is described whereby the hydraulic resistance of heat exchangers is reduced by utilizing high parallel flow technology. The objective is to eliminate the need for increased fluid pressures.

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Highly Parallel Flow to Reduce Hydraulic Resistance of Heat Exchangers

       A technique is described whereby the hydraulic resistance
of heat exchangers is reduced by utilizing high parallel flow
technology.  The objective is to eliminate the need for increased
fluid pressures.

      Typically, supply and return coolant fluid heat exchangers (*),
such as microchannel cooling systems used to cool semiconductor
circuit chips, provide excellent thermal conductivity.  However, they
require substantial fluid pressures, which in turn requires high
quality plumbing.  This complicates multi-chip module construction,
especially reworkability.

      In order to reduce the hydraulic resistance caused by increased
fluid pressures, the concept described herein provides supply and
return coolant fluid at many points throughout the area of the heat
exchanger plate, rather than just at the edges of the plate.  Use is
made of a self-aligned X-Y structure between grooves in the first
layer and the channels of the second layer and ducts in the third
layer, etc.  Therefore, the flow is much more parallel and the
hydraulic resistance is quadratically reduced.  In the uppermost
layer, the supply and return conduits are tapered in complementary
directions.

      In the heat exchanger (HEX) anatomy, each chip is bonded
directly to an individual HEX.  The first layer of the HEX is a
silicon chip with fine etched cooling grooves.  Coolant is supplied,
or returned, at each intersection between the grooves in the first
layer of the HEX, and the perpendicular channels in the second layer.
Therefore, each groove has six coolant supply points and five
intervening return points.  They effectively divide each groove into
ten segments, connected in parallel rather than in series.  No
explicit barrier exists within each groove.  The third layer has
three supply ducts interleaved with two return ducts.  All of the
ducts run perpendicular to the second layer channels and connect to
each of the channels as five parallel segments.  Because the flow is
perpendicular in successive layers, the HEX is self-aligning and
virtually all transverse dimensions are not critical.

      The first layer is fabricated in silicon.  It has excellent
thermal conductivity and its thermal expansion matches the integrated
circuit (IC) chip.  The other HEX layers are glass, fabricated by
etching or ultrasonic or molding methods.  All interlayer contact
surfaces are flat, which facilitates bonding and sealing.  Bonding
the silicon to glass, using the Mallory Process, is performed by
applying simultaneous heat and voltage to cause ion diffusion.  The
bonding of silicon to silicon is performed by first depositing an
ultra-thin glass layer, and again using the Mallory Process.  A
variation would use silicon instead of glass for the latter HEX
layers.

      The overall result is a flow topology that decreases the
hydraulic resistance 100-fold, as compared...