Photocopying – Contact printing
Reexamination Certificate
2003-05-22
2004-08-31
Rutledge, D. (Department: 2851)
Photocopying
Contact printing
C355S087000
Reexamination Certificate
active
06784979
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a full-contact type exposure device
2. Related Art
The photolithography method has been applied widely in various fields, wherein a prescribed pattern is photographically imprinted by an exposure device on the surface of a substrate coated with photosensitive materials such as the photo resist, thereafter the pattern is formed on the substrate by etching process. Printed circuit boards have also been fabricated by using an exposure device in recent years.
In this exposure device, in order to increase the adherence of a photo mask depicted with an original pattern picture to a board during exposure, a vacuum full-contact method, that establishes full contact by evacuating the gap between the two, is widely employed. An exposure device of this method is referred to as full-contact exposure device.
OBJECT OF THE INVENTION
However, it is difficult to establish a completely uniform full contact of the photo mask with the board. A problem has been a tendency of a slight air residue left in the center area of the board.
If an air exists between the photo mask and the board, a complete full contact of the photo mask with the board cannot be obtained, and thus the decreased resolution degrades the exposure accuracy because the exposure rays spread after passing through the photo mask before irradiating the board.
A method has been conventionally developed to pressure the photo mask from behind, thereby bending the photo mask when making contact with the board. However, this method may increase the adherence in the center area but has a shortcoming in degrading the adherence around the periphery.
A technique to improve the adherence in the periphery by making the photo mask large relative to the board has also been proposed, but there still have been problems such as cost increase and inefficiency in parts replacement operation due to the large-scale photo mask, and deterioration of adherence in the center portion because the photo mask may bend further below the board.
The objective of the invention is to resolve such problems of the conventional technology described above.
SUMMARY OF THE INVENTION
In order to achieve the objective mentioned above, a full-contact type exposure device of the invention comprises a photo mask depicted with a pattern to be exposed, contacting an exposure object for exposure; means for moving said photo mask and exposure object relatively closer to each other to allow full contact; position holding means for holding said photo mask at a first position where the photo mask partially contacts the exposure object, and for holding the photo mask at a second position where the photo mask entirely contacts the exposure object; means for sealing between said photo mask and the object to be exposed; and means for vacuuming between said photo mask and the object to be exposed.
In the above configuration, because the photo mask and the object are held in the first position partially contacting each other first and then they are held in the second position, it prevents air from being left in between the photo mask and the exposure object, therefore the adherence improves.
It is preferred to configure said first position and second position modifiable so as to be flexible in various conditions.
It is further preferred that said means for sealing seals between the photo mask and the exposure object at least in between the first position and the second position, and said means for vacuuming vacuums between the photo mask and the exposure object at least in between the first position and the second position, wherein the photo mask and the exposure object are partially contacted in said first position and then completely contacted in the second position by vacuuming between them.
REFERENCES:
patent: 3711081 (1973-01-01), Cachon
patent: 4888488 (1989-12-01), Miyake
patent: 5017960 (1991-05-01), Tuulse
patent: 5206680 (1993-04-01), Dillow
patent: 6459474 (2002-10-01), Okada
patent: 2003/0016342 (2003-01-01), Asami
Momii Isao
Tajima Tsunesou
Adtec Engineering Co., Ltd.
Rutledge D.
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