Electric heating – Metal heating – By arc
Reexamination Certificate
1999-02-18
2001-10-09
Evans, Geoffrey S. (Department: 1725)
Electric heating
Metal heating
By arc
C219S121680, C219S121820, C219S121830
Reexamination Certificate
active
06300594
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a method and apparatus for machining an electrically conductive film, and more particularly to a method and apparatus for removing portions of an electrically conductive film formed on an insulating substrate for patterning electrodes on the surface of the insulating substrate that forms part of a touch panel, a liquid crystal panel, or the like.
2. Description of the Related Art
Conventionally, touch panels have been used as means for users to input information to a variety of electronic devices. In addition, liquid crystal panels have been used as display means associated with electronic devices. Such touch panels and liquid crystal panels are constructed such that a pair of insulating substrates having transparent electrodes, each made of a transparent conductive film, formed on respective surfaces thereof are bonded so that the transparent electrodes are opposite to each other. In addition, for a touch panel, the pair of substrates are arranged in opposition with a spacer having a predetermined height (for example, 9-12 &mgr;m) interposed therebetween to prevent the transparent electrodes from contacting each other in a normal state.
The respective transparent electrodes formed on the surface of the insulating substrate are separated by slit-like gaps to prevent adjacent transparent electrodes from contacting each other. Conventionally, the transparent electrodes on the insulating substrate have been formed mainly by a photolithographic method including etching processing. The photolithographic method involves forming an electrically conductive film over an entire surface of an insulating substrate by vacuum deposition or the like, forming a resist pattern on the electrically conductive film, and then removing exposed portions of the electrically conductive film by an etchant which dissolves such exposed portions.
The use of the photolithographic method, however, is not so favorable from a viewpoint of environmental preservation, because the photolithographic method involves wasted photoresist developing solution, etchant and so on.
In addition, when a pattern and/or shape of transparent electrodes are to be changed, a mask must be newly created from the photolithographic method, so that the photolithographic method experiences a low machining efficiency, and difficulties in supporting multi-product small-amount production and reducing the cost. Particularly, even the formation of several slits through an electrically conductive film on an insulating substrate as is the case of a hybrid type touch panel requires the same photolithographic process as a digital type touch panel which involves the formation of several hundred slits. Therefore, reduction in waste liquids and cost has been difficult although conductive film are machined only in small areas.
As a method and apparatus for machining an electrically conductive film that are free from the need for a waste liquid treatment, which has been involved in the photolithographic method including etching processing, inexpensive, and suitable for multi-product small-amount production, it is contemplated that a laser beam is irradiated as an energy beam. However, experiments and so on diligently conducted by the present inventors on the machining of a electrically conductive film with the laser irradiation have revealed that an energy distribution on the cross section of laser light may cause troubles such as irregular widths and undulated shapes of machined slits, a portion of conductive film left unremoved, a deeply excavated insulating substrate at a position corresponding to the center of laser light, and so on.
It should be noted that the above-mentioned troubles such as variations in machined dimensions, partially unremoved conductive film, damaged insulating substrate and so on could be experienced not only when an electrically conductive film is irradiated with the laser light for machining but also when it is machined through irradiation with a light beam other than a laser beam, and other energy beams such as an X-ray beam, a charged particle beam and so on.
OBJECT AND SUMMARY IN THE INVENTION
The present invention has been made in view of the problems mentioned above, and its object is to provide a method and apparatus for machining an electrically conductive film at a low cost, suitable for multi-product small-amount production, which is less prone to variation in resulting dimensions, a partially remaining conductive film, damages to an insulating substrate, and so on after machining, while eliminating the need for a waste liquid treatment, which would be required when the photolithographic method including etching processing is employed.
To achieve this and other objects, according to a first aspect, the present invention provides a method of machining an electrically conductive film formed on a surface of an insulating substrate to remove portions of the electrically conductive film, which includes the steps of making uniform an energy distribution on a cross section of an energy beam, selectively irradiating the uniform energy beam to the electrically conductive film on the insulating substrate, and removing portions of the electrically conductive film.
In the method according to the first aspect, since the energy beam is selectively irradiated to the electrically conductive film on the insulating substrate to remove or machine portions of the electrically conductive film, the need for a waste liquid treatment, which would be required when using a photolithographic method including etching processing, is eliminated. In addition, since a portion to be removed of the electrically conductive film on the insulating substrate can be varied by changing a position to which the energy beam is irradiated, the method of the present invention is less expensive and more preferable for multi-product small-amount production at compared with the photolithographic method which involves creation of a new mask.
Also, since the energy distribution on the cross section of the laser light irradiated to the electrically conductive film is made uniform, the method of the present invention can reduce variations in resulting dimensions, a partially remaining conductive film, damages to an insulating substrate, and so on after machining.
Preferably, the energy beam is laser light. In this case, the laser light is selectively irradiated to the electrically conductive film on the insulating substrate to remove or machine portions of the electrically conductive film. Also, a portion to be removed of the electrically conductive film on the insulating substrate can be varied by changing a position to which the laser light is irradiated.
Also preferably, the insulating substrate and the electrically conductive film are transparent, and the step of irradiating the energy beam includes forming a slit through the transparent conductive film on the transparent insulating substrate.
Since the transparent conductive film on the transparent insulating substrate is formed with a slit by irradiating the energy beam thereto, a touch panel, a liquid crystal panel or the like having transparent electrodes can be produced at a lower cost in a multi-product small-amount production scheme without requiring a waste liquid treatment which would be involved in the photolithographic method including etching processing.
In addition, since the energy distribution on the cross section of the energy beam irradiated to the electrically conductive film is made uniform, the method of the present invention can reduce variations in the width of a resulting slit formed through the electrically conductive film, a partially remaining conductive film in the slit, damages to an insulating substrate on the bottom of the slit, and so on.
In a method of machining an electrically conductive film, particularly adapted to machine an electrically conductive film which has a wiring pattern made of an electrically conductive paste formed thereon, an energy beam is irradiated to form slit
Kinoshita Makoto
Kobayashi Takeshi
Evans Geoffrey S.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh Microelectronics Company, Ltd.
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