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Healing Surface Defects of Ceramic Multichip Carriers by a Sol/ Gel Sinter Process

IP.com Disclosure Number: IPCOM000121462D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 3 page(s) / 104K

Publishing Venue

IBM

Related People

Arenz, T: AUTHOR [+4]

Abstract

Ceramics and glass ceramics are permanently damaged during surface treatment because of their ceramic microstructure and lacking plasticity. As a result of such damage, thin metallic conductors cannot be readily applied to them. For an Al2O3 ceramic material, a sol/gel process has been developed which heals the damaged surface by a colloidal suspension, drying and heat treatment. The substrates have very low roughness values.

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Healing Surface Defects of Ceramic Multichip Carriers by a Sol/ Gel
Sinter Process

      Ceramics and glass ceramics are permanently damaged
during surface treatment because of their ceramic microstructure and
lacking plasticity.  As a result of such damage, thin metallic
conductors cannot be readily applied to them.  For an Al2O3 ceramic
material, a sol/gel process has been developed which heals the
damaged surface by a colloidal suspension, drying and heat treatment.
The substrates have very low roughness values.

      The substrates and their surface roughness, which is determined
by the way they are produced, are planarized by a sol/gel process.
For this purpose, a sol or a mixture of sol and reactive glass
powder, yielding a sol/gel, is applied to the substrate surface by
spinning, dipping, centrifuging or coating.  The viscosity, the
amount of solids, and thus the volume reduction occurring during the
drying and subsequent heat treatment steps, may be controlled by the
mixture of sol and the reactive glass powder obtained in the sol/gel
process.  This permits filling voids and surface defects by the
solid-enriched sol. The applied sol leads to gel formation of the
thin layer or such gel formation may be activated by a catalyst in
the vapor phase.  In a subsequent heat treatment step, the gel is
sintered and transformed to a ceramic material by crystallization.

      There is no corrosion between the sol, gel and the ceramic
material of which the substrate consists.  The coefficient of
expansion of the ceramic material obtained by the sol/gel process is
less than that of the substrate.  As a result the tensile stress
exerted on the ceramic filling the holes, voids and flaws is
non-detrimental.  The sinter and melting temperatures are much lower
than the temperatures of the ceramics used for the substrate.

      A glass or a glass ceramic of the chemical composition
      20 MgO    18 Al2O3  62 SiO2   in percent by weight
has a cordieritelike structure.  As there are no alkalies, such as
sodium, corrosive mechanisms are prevented.  In the ternary system
MgO - Al2O3 - SiO2, the above-mentioned composition has the lowest
melting temperature at about 1355oC and may be used for Al2O3
substrates, the maximum sinter temperature of which...