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Laser CVD of Metals On Free-Standing Beams in Thin Film Carriers

IP.com Disclosure Number: IPCOM000120038D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 52K

Publishing Venue

IBM

Related People

Baum, TH: AUTHOR [+6]

Abstract

Disclosed is a process for selective metal deposition onto free- standing structures commonly found in thin film carriers. This avoids photolithographic and electrolytic plating processes, thereby reducing the overall cost of these parts. Also, this dry process reduces the chemical usage in production.

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Laser CVD of Metals On Free-Standing Beams in Thin Film Carriers

      Disclosed is a process for selective metal deposition
onto free- standing structures commonly found in thin film carriers.
This avoids photolithographic and electrolytic plating processes,
thereby reducing the overall cost of these parts.  Also, this dry
process reduces the chemical usage in production.

      Current thin film packages, such as tape automated bonding
(TAB) packages, consist of metal circuitization on a polyimide
carrier.  Integrated circuit chips are often thermocompression-bonded
to the inner lead bond (ILB) fingers located at the center of the
part.  The fingers are unsupported in this area, although the
remainder of the line is found on the dielectric substrate.  To
insure bonding, the ILB fingers are coated with gold
electrochemically to an approximate depth of 0.5 u.

      Laser Chemical Vapor Deposition (LCVD) is a photothermal
process where the laser provides the thermal energy to a substrate to
dissociate an organometallic compound (*).  A pure metal is
deposited.  The deposition is selective since dissociation occurs
close to the spot heated.  LCVD has previously been used to repair
and seed metal lines on a variety of substrates.

      LCVD can be used to selectively deposit gold on the ILB fingers
of TAB products.  This has been accomplished using dimethyl gold (II)
hexafluoroacetylacetonate and the experimental apparatus given in
[*].  Optical and...