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Eliminating Surface Defects On Planarized Ceramic Substrates

IP.com Disclosure Number: IPCOM000119351D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 91K

Publishing Venue

IBM

Related People

Boecker, J: AUTHOR [+3]

Abstract

This article describes a method of eliminating surface defects occurring during the planarization of MLC (multilayer ceramic) substrates.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Eliminating Surface Defects On Planarized Ceramic Substrates

      This article describes a method of eliminating surface
defects occurring during the planarization of MLC (multilayer
ceramic) substrates.

      To increase the wiring density, high-speed computers produced
by state-of-the-art methods have part of their wiring arranged on the
chip carrier surface by thin-film technology.  However, to be
effective, thin-film technology requires planar surfaces.  For this
purpose, the chip carriers which are non-planar or cambered after
sintering have to be lapped and planarized.  On ceramic substrates,
this frequently opens and increases the sinter pores.  The diameter
of most pull-outs produced in that way are about 5 to 50 mm.
Subsequently, as conductors of a width of about 14 mm are deposited
on the ceramic surface by special metallization processes, the
function of the chip carriers is seriously impaired by such surface
defects.

      The proposed method allows pull-out defects, in particular
those of diameters > 5 mm, occurring during the planarization of MLC
substrates, to be readily, economically and permanently eliminated.
For this purpose, the planarized ceramic substrate is covered with
liquid or pasty compounds by spinning, coating, knife-coating or
other known processes.  This is followed by drying and respectively
tempering and baking at temperatures ranging from 100 to 1200oC.  The
substrate thus treated is polished to remove excess coating or
filling material and may then be processed further without the usual
number of pull-outs (50/mm2 (10-50 mm), 10/mm2 (15-25 mm), 1/mm2
(25-50 mm)).

      The liquid or pasty compounds are produced by mixing the
fillers with water and/or organic solvents or with liquid
co-components of the filler systems.  For this purpose, surfactants
and ultrasound may be used to advantage.  The particle size of the
materials is < 2 mm, preferably < 1 mm.

      Suitable filler and coating materials are those which during
tempering at 860oC and polishing continue to adhere within the pull-
outs and which do not lead to cracks.  The materials must be alkali-
free to avoid electromigration. Some suitable coating compounds are
listed below.
      aluminum oxide
      aluminum oxide/aluminum hydroxide
      aluminum oxide/organosilane
      aluminum oxide/siloxane
      aluminum oxide/silicate
 ...