Browse Prior Art Database

Wirebonding Technique Onto Polymer Thick Film

IP.com Disclosure Number: IPCOM000121280D
Original Publication Date: 1991-Aug-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 36K

Publishing Venue

IBM

Related People

Kato, T: AUTHOR [+3]

Abstract

Disclosed is a technique to ultrasonically bond an aluminum wire to conductive polymer thick film surface. Typically, conductive polymer thick film paste consists of metal filler and polymer-solvent vehicle. After screening and curing the paste, polymer thick film acts as a conductive circuitry on printed circuit board.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 88% of the total text.

Wirebonding Technique Onto Polymer Thick Film

      Disclosed is a technique to ultrasonically bond an
aluminum wire to conductive polymer thick film surface.  Typically,
conductive polymer thick film paste consists of metal filler and
polymer-solvent vehicle.  After screening and curing the paste,
polymer thick film acts as a conductive circuitry on printed circuit
board.

      The ultrasonic wirebonding onto polymer thick film has some
difficulties, due to the following reasons:
(1) Metal fillers have a thin polymeric layer on their surface.  The
polymeric layer keeps the bonding wire from contacting with the metal
filler surface directly.
(2) While the paste is cured under an elevated temperature, the
oxidation of the metal filler occurs.  The existing oxidized layer on
the metal fillers makes bondability poor.
(3) The large surface roughness of the polymer thick film reduces an
effective interface area between the bonding wire and the metal
fillers.

      According to this new method, an ultrasonically wirebonding
onto a conductive polymer thick film can be realized.  This method
includes the following steps typically:
1.  A surface modification using alkaline or acid washing in order to
remove the oxidized layer and the polymeric layer which exist on the
polymer thick film surface.
2.  A metal plating to the polymer thick film surface, such as Ni
plating or Au plating.  In order to smooth the surface roughness,
plating conditions should be careful...