Material and method for making an electroconductive pattern

Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...

Reexamination Certificate

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C430S165000, C430S166000, C430S188000, C430S192000, C430S193000, C430S326000, C430S270100

Reexamination Certificate

active

06638680

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a material and a 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.
EP-A 614 123 discloses a water-soluble electrically conductive composition of matter comprising a polyacid and a polymer comprising at least one conjugated region composed of repeating units which contain a conjugated basic atom. However, as water-soluble electrically conductive polymer comprising at least one conjugated region composed of repeating units which contain a conjugated basic atom, only polyaniline and substituted polyanilines are exemplified.
EP-A 382 046 discloses an electrically conductive resist material, essentially comprising at least one ionic radiation-sensitive polymer and a soluble electrically conductive oligomer or a soluble electrically conductive polymer. Polymers of substituted thiophenes are exemplified, but no specific ionic radiation-sensitive polymers.
EP-A 338 786 discloses a negative working, photosensitive, overlay color proofing film which comprises, in order: (i) a transparent substrate; (ii) a photosensitive layer on the substrate, which photosensitive layer comprises a light sensitive, negative working, polymeric diazonium compound which is the polycondensation product of 3-methoxy-4-diazodiphenylamine sulfate and 4,4′-bis-methoxymethyl diphenyl ether precipitated as the chloride salt, which diazonium compound is present in sufficient amount to photosensitize the layer; and a water insoluble, water swellable binder resin in sufficient amount to bind the layer components in a uniform film; and at least one colorant in sufficient amount to uniformly color the layer; wherein upon imagewise exposure of the photosensitive layer to sufficient actinic radiation the film is capable of being developed with water alone.
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.
OBJECTS OF THE INVENTION
It is an aspect of the present invention to provide a material having a outermost layer that can be processed to an electroconductive pattern by a simple, convenient method which involves a low number of steps and which does not require the use of hazardous chemicals.
SUMMARY OF THE INVENTION
An electroconductive pattern can be realized with the materials of the present invention, which are optionally conductivity enhanced, by pattern-wise exposure, with or without a subsequent single wet processing step, and optional conductivity enhancement. 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 an 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 light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer.
These objects are also realized by a method of making an electroconductive pattern on a support comprising the steps of:
providing a material as disclosed above;
image-wise exposing the material thereby obtaining a differentiation of the removability, optionally with a developer, of the exposed and the non-exposed areas of the outermost layer;
processing the material, optionally with the developer, thereby removing areas of the outermost layer; and
optionally treating the material to increase the electroconductivity of the non-removed areas of the outermost layer.
These objects are also realized by a method of making an electroconductive pattern on a support without a removal step comprising the steps of:
providing a material for making an electroconductive pattern, said material comprising a support and a light-exposure differentiable element, characterized in that said light-exposure differentiable element comprises an outermost layer containing a polyanion and a polymer or copolymer of a substituted or unsubstituted thiophene having a surface resistivity lower than 10
6
&OHgr;/square, and optionally a second layer contiguous with the outermost layer; and wherein the outermost layer and/or said optional second layer contains a bis(aryl diazosulfonate) compound according to formula (I):
MO
3
S—N═N—Ar—L—Ar—N═N—SO
3
M  (I)
where Ar is a substituted or unsubstituted aryl group, L is a divalent linking group, and M is a cation; capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer; and
image-wise exposing the material thereby obtaining reduction in the conductivity of the exposed areas relative to

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