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Diamond-Like Carbon Coating for Corrosion Protection of Capture Pads Bottom Surface Metallurgy in Ceramic or Glass Ceramic Substrates

IP.com Disclosure Number: IPCOM000108467D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 46K

Publishing Venue

IBM

Related People

Bakhru, N: AUTHOR [+4]

Abstract

A diamond-like carbon (DLC) coating is applied on the ceramic substrate of the chip module after the I/O pins have been brazed to the I/O pads. DLC is an extremely inert material and can hermetically seal the substrate from humidity and other atmospheric contaminants, thus preventing corrosion of the metals.

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Diamond-Like Carbon Coating for Corrosion Protection of Capture Pads Bottom Surface Metallurgy in Ceramic or Glass Ceramic Substrates

       A diamond-like carbon (DLC) coating is applied on the
ceramic substrate of the chip module after the I/O pins have been
brazed to the I/O pads.  DLC is an extremely inert material and can
hermetically seal the substrate from humidity and other atmospheric
contaminants, thus preventing corrosion of the metals.

      The Cr/Cu/Ti/Au bottom surface metallurgy (BSM) currently
practiced in the ceramic or glass ceramic substrate was found to be
prone to corrosion by chlorine and humidity.

      Diamond-like carbon is characterized by extreme chemical
inertness (*).  Using a DC-biased substrate in a DC or RF plasma
deposition apparatus, a conformal DLC layer can be deposited on the
structure, as indicated in the figure. A film 1 - 1.5 mm can be
deposited in less than 1 hour, and such films can provide hermetic
sealing of the BSM and prevent corrosion of the I/O pads.

      The deposition of the DLC is to be done after the brazing of
the pins.  DLC deposited on the shafts of the pins can be removed by
RIE in an oxygen plasma using a molybdenum mask to protect the
overcoat on the BSM surface.

      Reference
(*)  A. Grill, B. S. Meyerson and V. Patel, "Diamond Like Carbon:
Preparation, Properties and Applications," IBM J. Res. Dev. 34 849
(1990).