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Use of Pliable Particle Technology for Forming Electrically Isolating Coating on Heat Sinks

IP.com Disclosure Number: IPCOM000102288D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Sagar, K: AUTHOR [+3]

Abstract

Disclosed is a process for forming an electrically insulating layer 25 on the walls of cylindrical cavities in heat sinks 21, used in chip cooling modules [1,2]. The cavities are coated with a uniform layer of aluminum 24 using pliable particle technology. The aluminum coating is anodized to form the electrically insulating layer 25, which isolates the chip 27 from the electrically grounded heat sink 21. Heat flows from the chip 27 through the piston 23 to the heat sink 21. The chip is bonded to a circuit board 20 using solder balls 22.

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Use of Pliable Particle Technology for Forming Electrically Isolating Coating on Heat Sinks

       Disclosed is a process for forming an electrically
insulating layer 25 on the walls of cylindrical cavities in heat
sinks 21, used in chip cooling modules [1,2].  The cavities are
coated with a uniform layer of aluminum 24 using pliable particle
technology.  The aluminum coating is anodized to form the
electrically insulating layer 25, which isolates the chip 27 from the
electrically grounded heat sink 21.  Heat flows from the chip 27
through the piston 23 to the heat sink 21.  The chip is bonded to a
circuit board 20 using solder balls 22.

      Pliable particle technology uses a slip casting method in which
a dispersion or slurry of aluminum particles in a binder solution is
applied directly to the cavity surfaces using a core rod to obtain a
hollow cup-shaped casting.  The coating, being pliable, can be
refinished as desired.

      The slip is formed using an organic binder, such as
polyvinylbutyral or polymethylmethacrylate (PMMA), dissolved in a
suitable solvent.  The rheology of the slip is suitably adjusted to
provide a uniform coating on the cavity surface. The current method
uses fine particles of aluminum mixed in a solution of PMMA dissolved
in ethylacetate solvent.  A dibutylphthalate plasticizer is also
added to the binder system to provide good dispersion of aluminum
particles and also to increase the flexibility of the cast layer.
The PMMA binder has a unique ability to comp...