Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-10-22
2001-09-04
Aftergut, Jeff H. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S099000, C156S275700, C156S321000, C156S322000, C349S122000, C349S190000, C425S025000
Reexamination Certificate
active
06284087
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an improved method for affixing two objects together with a light/heat curable sealant and, more particularly, to a method and system for curing such a sealant that is shadowed by metallization components.
BACKGROUND OF THE INVENTION
Flat computer display panels (see
FIGS. 1
a
-
1
c
) require attachment of two glass substrates
6
and
8
. One substrate
6
contains an active device area
10
of thin film transistors (also referred to as TFT's) and accompanying circuitry. Second substrate
8
comprises a color filter
11
. About the edges of color filter
11
there is a peripheral region
12
consisting of a layer of chrome oxide
14
over which there is deposited a layer of chrome
16
. In some cases, peripheral region
12
consists of an organic resin. In both cases, these layers are referred to as black matrix
17
.
A sealant
18
is applied just prior to attachment of substrates
6
and
8
. Circuitized substrate
6
is placed over sealant
18
which results in a major fraction of sealant
18
spreading into the black matrix region. Curing of sealant
18
generally requires the use of uv light, in the range of 350-360 nm in wavelength (although certain sealants respond to different wavelengths, they are not generally used for flat display panels). The incident uv light stimulates certain initiators in sealant
18
that cause a reaction leading to cure or cross linking therein, resulting in a leak-tight seal.
However, there is a curing problem in parts of this sealant region where there is metallization
22
. Metallization
22
comprises data and gate lines of the TFT substrate that extend out from the sealed region for connection to driving electronic circuitry. In metallized regions located above sealant
18
, the uv light is shadowed and sealant
18
beneath the shadowing metallization tends to remain uncured.
Accordingly, it is an object of the invention to provide an improved method for affixing two objects together with a curable sealant.
It is a further object of the invention to provide a method and system for curing a sealant that is shadowed by metallization components.
SUMMARY OF THE INVENTION
The present invention applies to flat panel displays where the inherent problem is one of shadowing of a curable sealant. The shadowing is caused by opaque metallization on one of two substrates that comprise component parts of the display panel. The metallization prevents photons from reaching the region of sealant immediately underneath the metallized pattern. This invention overcomes the uncured sealant problem (also referred to as the shadowing effect) by redirecting an incident photon beam to reach the shadowed regions. In a first embodiment, a surface of the black matrix
17
is roughened to cause diffusion of the reflected incident light, thus enabling redirected photons to bring about a complete cure of the sealant, i.e., activation of initiators, leading to polymerization. Various methods are described to obtain the roughened black matrix
17
.
Alternatively, the light beam may be intensity modulated and/or an additional heat source provided to cause heating in the region of the metallization. In this combined heating-photon method, a dual cure (i.e., light/heat) sealant will cure by either one or a combination of optical and thermal excitations to excite the curing initiators.
REFERENCES:
patent: 4523102 (1985-06-01), Kazufumi et al.
patent: 6179679 (2001-01-01), von Gutfeld et al.
Glownia James H.
von Gutfeld Robert J.
Aftergut Jeff H.
International Business Machines - Corporation
Ohlandt Greeley Ruggiero & Perle LLP
Tolin Michael A.
Underweiser Esq Marian
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