Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
2002-06-18
2003-09-23
Chu, John S. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Diazo reproduction, process, composition, or product
Composition or product which contains radiation sensitive...
C430S164000, C430S176000, C430S188000, C430S270100, C430S311000
Reexamination Certificate
active
06623903
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a material and method for making an electroconductive pattern.
BACKGROUND OF THE INVENTION
For the fabrication of flexible LC displays, electrolumin-escent devices and photovoltaic cells transparent ITO (indium-tin oxide) electrodes are used. These electrodes are made by vacuum sputtering of ITO onto a substrate. This method involves high temperatures, up to 250° C., and therefore glass substrates are generally used. The range of potential applications is limited, because of the high fabrication costs, the low flexibility (pliability) and stretchability as a consequence of the brittleness of the ITO layer and the glass substrate. Therefore the interest is growing in all-organic devices, comprising plastic resins as a substrate and organic electroconductive polymer layers as electrodes. Such plastic electronics allow the realization of low cost devices with new properties (Physics World, March 1999, p.25-39). Flexible plastic substrates can be provided with an electroconductive polymer layer by continuous roller coating methods (compared to batch process such as sputtering) and the resulting organic electrodes enable the fabrication of electronic devices characterised by a higher flexibility and a lower weight.
The production and the use of electroconductive polymers such as polypyrrole, polyaniline, polyacetylene, polyparaphenylene, polythiophene, polyphenylenevinylene, polythienylenevinylene and polyphenylenesulphide are known in the art.
EP-A 440 957 discloses dispersions of polythiophenes, constructed from structural units of formula (I):
in which R
1
and R
2
independently of one another represent hydrogen or a C
1-4
-alkyl group or together form an optionally substituted C
1-4
-alkylene residue, in the presence of polyanions. Furthermore, EP-A-686 662 discloses mixtures of A) neutral polythiophenes with the repeating structural unit of formula (I),
in which R
1
and R
2
independently of one another represent hydrogen or a C1-C4 alkyl group or together represent an optionally substituted C1-C4 alkylene residue, preferably an optionally with alkyl group substituted methylene, an optionally with C1-C12-alkyl or phenyl group substituted 1,2-ethylene residue or a 1,2-cyclohexene residue, and B) a di- or polyhydroxy- and/or carboxy groups or amide or lactam group containing organic compound; and conductive coatings therefrom which are tempered at elevated temperature, preferably between 100 and 250° C., during preferably 1 to 90 seconds to increase their resistance preferably to <300 ohm/square.
Coated layers of organic electroconductive polymers can be structured into patterns using known microlithography techniques. In WO-A-97 18944 a process is described wherein a positive or negative photoresist is applied on top of a coated layer of an organic electroconductive polymer, and after the steps of selectively exposing the photoresist to UV light, developing the photoresist, etching the electroconductive polymer layer and finally stripping the non-developed photoresist with an organic solvent, a patterned layer is obtained. A similar technique has been described in 1988 in Synthetic Metals, volume 22, pages 265-271 for the design of an all-organic thin-film transistor. Such methods are cumbersome as they involve many steps and require the use of hazardous chemicals.
EP-A 399 299 discloses a structure comprising: a polymeric material; the polymeric material being selected from the group consisting of substituted and unsubstituted polyparaphenylene-vinylenes, polyanilines, polyazines, polythiophenes, poly-p-phenylene sulfides, polyfuranes, polypyrroles, polyselenophenes, polyacetylenes formed from soluble precursors and combinations thereof and blends thereof with other polymers; preselected regions of the polymer material being electrically conductive; the conductive regions being substantially insoluble; and the remainder of the material being substantially soluble.
U.S. Pat. No. 5,427,841 discloses a laminated structure comprising an electrically insulating substrate carrying a polymer layer consisting essentially of a polymer selected from the group of poly(3,4-ethylenedioxythiophene, poly(3,4-diethylenedioxythiophene) wherein the ethylene group is substituted with C
1-12
alkyl group, poly(3,4-ethylenedioxythiophene) wherein the ethylene group is substituted with an alkoxy group, and oligomers of ethylenedioxy-thiophene, the layer having a sheet resistance of maximally 1000 &OHgr;/square, and a pattern of second substantially non-conductive portions whose sheet resistance is at least a factor of 10
6
higher than that of the conductive polymer in the first portions, a metal layer being deposited into the electrically conductive first portions of the polymer layer. In Exemplary embodiment 1 surface resistivity differentiation is realized by doping a poly(3,4-ethylenedioxythiophene)-containing layer with imidazole and pattern-wise exposure with UV-light (&lgr;<300 nm) by means of a mercury lamp.
OBJECTS OF THE INVENTION
It is an aspect of the present invention to provide a material having an outermost layer that can be processed to an electroconductive pattern by a simple, convenient method.
SUMMARY OF THE INVENTION
An electroconductive pattern can be realized with the materials of the present invention by pattern-wise exposure without removal of the unexposed or exposed areas, with or without a subsequent single wet processing step. No etching liquids or organic solvents are required.
The aspects of the present invention are realized by a material for making an electroconductive pattern, the material comprising a support and a light-exposure differentiable element, characterized in that the light-exposure differentiable element comprises a conductivity enhanced outermost layer containing a polyanion and a polymer or copolymer of a substituted or unsubstituted thiophene, and optionally a second layer contiguous with the outermost layer; and wherein the outermost layer and/or the optional second layer contains a monodiazonium salt capable upon exposure of reducing the conductivity of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer.
The aspects of the present invention are further realized by a material for making an electroconductive pattern, the material comprising a support and a light-exposure differentiable element, characterized in that the light-exposure differentiable element comprises an outermost layer having a surface resistance lower than 10
6
&OHgr;/square containing a polyanion and a polymer or copolymer of a substituted or unsubstituted thiophene, and optionally a second layer contiguous with the outermost layer; and wherein the outermost layer and/or the optional second layer contains a monodiazonium salt capable upon exposure of reducing the conductivity of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer.
The aspects of the present invention are also realized by a method of making an electroconductive pattern on a support comprising the steps of:
providing a material for making an electroconductive pattern as in the two embodiments disclosed above; and
image-wise exposing the material thereby obtaining reduction in the conductivity of the exposed areas relative to non-exposed areas, optionally with a developer.
Further advantages and embodiments of the present invention will become apparent from the following description.
DETAILED DESCRIPTION OF THE INVENTION
The term “support” means a “self-supporting material” so as to distinguish it from a “layer” which may be coated on a support, but which itself is not self-supporting. It also includes any treatment necessary for, or layer applied to aid, adhesion to the light-exposure differentiable element.
The term electroconductive means having a surface resistance below 10
6
&OHgr;/square. Antistatic materials have surface resistances in the range from 10
6
to 10
11
&OHgr;/square and cannot be used as an electrode.
Conductivity enhancement refers to a proc
AGFA-Gevaert
Chu John S.
Leydig , Voit & Mayer, Ltd.
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