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Browse Prior Art Database

Aluminum Nitride Heat Sink to the Chip

IP.com Disclosure Number: IPCOM000099201D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 2 page(s) / 86K

Publishing Venue

IBM

Related People

Suryanarayana, D: AUTHOR

Abstract

Disclosed is a method to enhance the power of flip-chips on polyimide thin film (TAB) using the aluminum nitride (AlN) ceramic as a heat material. The ceramic cut to the size of the chip was on the back of the silicon chip using a emulsion as an adhesive.

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Aluminum Nitride Heat Sink to the Chip

       Disclosed is a method to enhance the power of flip-chips
on polyimide thin film (TAB) using the aluminum nitride (AlN) ceramic
as a heat material.  The ceramic cut to the size of the chip was on
the back of the silicon chip using a emulsion as an adhesive.

      Thermal management in flip-chip packages, e.g., ceramic (MC),
metallized ceramic polyimide (MCP), has been a constant problem,
since the heat has to through controlled collapse chip connection
(C4) solder and to the substrate.  The current alumina ceramic with
thermal conductivity of 26 W/mK cannot complete heat removal from the
chips.  Thus external options were pursued in the ceramic modules
(MC, etc.) using aluminum metallic heat sinks assembled on with
thermal grease as an adhesive material.  However, metallic heat sinks
are bulky and expensive and may not desirable in future plastic
packages using polyimide thin products such as decals, TABs, etc.
The heat sink is preferred to have the following physical  (i) high
thermal conductivity, (ii) low thermal coefficient matched to
silicon, (iii) good insulation, and (iv) light weight.  To date, the
known material is a ceramic, namely, AlN, which offers thermal
conductivity (200 W/mK) close to aluminum metal a matched thermal
expansion coefficient with the chip. low thermal expansion property
of AlN ceramic enables mechanical fatigue life for the joint,
compared to under accelerated thermal cycle testing.

      In this study, AlN ceramic (of 60 mils in thickness) was from
vendors and cut to the size of a chip (0.5 cm 0.5 cm).  The AlN
ceramic had a smooth surface finish of 0.5 m.  A fluoropolymeric
(TEFLON*...