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Process for Forming Tab Contact Pads, Alignment Guides and Ink Flow Channels for Thermal Ink Jet Print Heads

IP.com Disclosure Number: IPCOM000122629D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 4 page(s) / 133K

Publishing Venue

IBM

Related People

Cakerice, L: AUTHOR [+4]

Abstract

The major components (Fig. 1) in a thermal ink jet print head consist of a silicon chip on which an array (or arrays) of thin film heaters is formed using: semiconductor-like fabrication processes and materials, a nozzle plate containing matching orifices; a patterned thin film structure sandwiched between the chip and the nozzle plate to provide ink passages to each heater, and electrical interconnections to energize the heaters. Precise alignment of the nozzle plate to the heater array is essential for ensuring high print head performance.

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Process for Forming Tab Contact Pads, Alignment Guides and Ink Flow
Channels for Thermal Ink Jet Print Heads

      The major components (Fig. 1) in a thermal ink jet print
head consist of a silicon chip on which an array (or arrays) of thin
film heaters is formed using:  semiconductor-like fabrication
processes and materials, a nozzle plate containing matching orifices;
a patterned thin film structure sandwiched between the chip and the
nozzle plate to provide ink passages to each heater, and electrical
interconnections to energize the heaters.  Precise alignment of the
nozzle plate to the heater array is essential for ensuring high print
head performance.

      Tape-automated bonding (TAB) interconnects are a most popular
means of providing power to the silicon chip (Fig. 2).  TAB meets all
the requirements for the thermal ink jet print head technology:  low
profile; strong, high instantaneous current capacity; low cost, etc.
A bonding interface needs to be established on the interconnection
pads of the silicon chip in order to join with the TAB.  This is
typically done by electrodepositing roughly 25-35 microns of gold on
top of each contact pad.  The gold pads are subsequently annealed to
a very low hardness condition so that metallurgically sound bonds to
the TAB can be formed, either by thermal-sonic or thermal-compression
techniques.

      The gold pad formation process (often called gold bumping in
the semiconductor industry) can be extended to pr...