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ELIMINATION OF EDGE BEAD IN SPIN COATING PROCESS

IP.com Disclosure Number: IPCOM000027317D
Original Publication Date: 1996-Apr-30
Included in the Prior Art Database: 2004-Apr-07
Document File: 2 page(s) / 81K

Publishing Venue

Xerox Disclosure Journal

Abstract

One form of thermal ink jet printhead comprises a heater plate or wafer which is bonded to a channel plate or wafer by a polyimide layer which is laid down on the heater plate by a spinning process. Because of the surface tension resulting from this process, beads 5-10 microns thick are formed at the edges of the heater plate as a consequence of the spinning process. As a result, when the two plates are mated together, the laminate is not in as close contact at the edges as at the center.

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XEROX DISCLOSURE JOURNAL

ELIMINATION OF EDGE BEAD IN SPIN COATING PROCESS US. C1.346/140 Ram S. Narang
Robert P. Altavela

Proposed Classification

Int. C1. Gold 15/16

1'1

XEROX DISCLOSURE JOURNAL - Vol. 21, No. 2 MarcWApril 1996 117

[This page contains 1 picture or other non-text object]

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ELIMINATION OF EDGE BEAD IN SPIN COATING PROCESS(Cont'd)

One form of thermal ink jet printhead comprises a heater plate or wafer which is bonded to a channel plate or wafer by a polyimide layer which is laid down on the heater plate by a spinning process. Because of the surface tension resulting from this process, beads 5-10 microns thick are formed at the edges of the heater plate as a consequence of the spinning process. As a result, when the two plates are mated together, the laminate is not in as close contact at the edges as at the center.

One method for eliminating the edge bead is to perform the spinning step while holding the wafer in a spring chuck 10 shown in side view in the figure. The inner portion of the chuck, where the wafer is held by a vacuum force, is about 18-20 mils below the outer portion of the chuck and has the same shape as the wafer including the large and small flats. The outer portion of the chuck has a groove 14 for placement of an O-ring 16 by screw 18 close to its periphery. Such an O-ring would provide a leak-proof seal when mated with a ring, with an exactly similar groove, from the top. Inbetween the groove and the inner part of the ch...