Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
2000-06-09
2001-02-20
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...
C430S173000, C430S181000
Reexamination Certificate
active
06190823
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a diazo-containing photosensitive material useful for the fabrication of photomasks.
BACKGROUND ART
It is known to use a photosensitive material having a transparent film on which a diazo-containing photosensitive layer capable of affording a light-shielding colored image as a photomask for the fabrication of printed wiring boards and various printing plates.
In the fabrication of a printed wiring board, a photosensitive resin layer is formed over a conductive layer such as a copper clad laminate. A photomask is superimposed on the photosensitive resin layer. Then, the photosensitive resin layer is exposed through the photomask using a contact printing device. The exposed photosensitive resin layer is developed to form a pattern. The conductive layer is then etched according to the pattern. The remaining photosensitive layer is thereafter removed to give a desired wiring pattern. The contact printing step has a great influence upon resolution of images and working efficiency in the production of printing wiring boards. In particular, when the photomask is not closely contacted with the photosensitive resin layer, Newton rings and air entrainment occur to cause cutting or distortion of wiring patterns. Thus, it is necessary to evacuate air between the photomask and the photosensitive resin layer for a long period of time in order to obtain good contact therebetween.
JP-A-H07-168306 discloses a diazo-containing photosensitive material having a transparent support, and a diazo-containing photosensitive layer provided over a surface of the support and including a binder, a diazo compound, a coupler and solid powder having an average particle diameter of 1-8 &mgr;m, wherein the diazo compound is represented by the following formula:
(wherein R
1
and R
2
stand, independently from each other, for a lower alkyl group and X stands for an anionic group), and wherein the coupler comprises phenylphenol and N-(2′-hydroxyalkyl)-&bgr;-resorcylamide. It has been found that a photomask obtained from the diazo-containing photosensitive material encounters a problem that the diazo-containing photosensitive layer, when contacted with a photosensitive resin layer during contact printing stage, is affected by monomers or a solvent contained in the photosensitive resin layer to cause deterioration of the durability of the diazo-containing photosensitive layer and lowering of pattern resolution. It has been also found that a surface of the diazo-containing photosensitive layer is apt be injured by frictional contact with working tables or with another diazo-containing photosensitive material during operation or storage.
U.S. Pat. No. 5,382,495 discloses a photosensitive material having an overcoat layer provided on a diazo-containing photosensitive layer so as to improve resistance to solvents and resistance to injury. When a latent image is produced on a photosensitive resin layer using a photomask obtained from the above photosensitive material, a problem of a reduction of the resolution of the image produced on the photosensitive resin layer is caused due to the presence of the overcoat layer between the photosensitive resin layer and the diazo-containing photosensitive layer. Another problem is also caused because it is very difficult to produce the diazo-containing photosensitive material.
It is an object of the present invention to provide a photosensitive material having a diazo-containing photosensitive layer, whose photosensitive layer has good resistance to solvents and to injury, which provides good contact with an original image film and with a photosensitive resin layer on a copper clad laminate layer, which is capable of affording a photomask that requires only a short period of time for removing air between the photomask and the photosensitive resin layer by suction, which gives a background (transparent portion) having good UV permeability, and which gives images having high resolution and excellent UV-shielding properties.
DISCLOSURE OF THE INVENTION
In accordance with the present invention there is provided a diazo-containing photosensitive material comprising a transparent support, and a diazo-containing photosensitive layer provided over a surface of said support and comprising a binder, a diazo compound and a coupler,
wherein said diazo compound is represented by the following formula:
wherein R
1
and R
2
stand, independently from each other, for a lower alkyl group and X stands for an anionic group,
wherein said coupler comprises phenylphenol and 3,5-dihydroxy-4-bromobenzoic acid, and
wherein said binder comprises a cellulose ester cross-linked with a lower-alkylated urea resin.
As the binder for the diazo-containing photosensitive material according to the present invention, there may be used a cellulose ester crosslinked with a lower-alkylated urea resin. A cellulose ester is excellent not only in transparency but also in permeability of ammonia used in development of an image-exposed material. Illustrative of suitable cellulose esters are cellulose diacetate, cellulose triacetate, cellulose acetate propionate, cellulose propionate, cellulose acetate and cellulose acetate butyrate. Above all, use of cellulose acetate propionate is preferred for reasons of transparency.
A lower-alkylated urea resin is a thermosetting product obtained by reacting a precondensate (such as dimethylol urea or its dimeric condensate) having a methylol group, obtained by condensing urea with formaldehyde, with a lower alcohol to convert the methylol group into an ether group. In the condensation reaction, formaldehyde is used in an amount of 0.5-4.0 moles, preferably 1.3-2.3 moles, per mole of urea. The lower alcohol has 1-6 carbon atoms. Butyl alcohol is preferably used. The lower-alkylated urea resin is used in the form of a powder or a solution (aqueous solution or a xylol/butanol solution). Such a lower-alkylated urea resin is commercially available as a trade name of “UVAN 10S60”, which is suitably used for the purpose of the present invention.
The diazo-containing photosensitive material obtained with the use of the lower-alkylated urea resin as a crosslinking agent has good resistance to solvents from a photosensitive resin layer and to surface injury. The crosslinking agent does not react with a diazo compound or a coupler and, thus, does not interfere the light transmission through non-image portions. Further, since the crosslinking agent permits crosslinking at a temperature of 120° C. or less, it is possible to suppress the coloration of the diazo-containing material during the preparation thereof.
The lower-alkylated urea resin crosslinking agent is generally used in an amount of 3-150 parts by weight per 100 parts by weight of the cellulose ester. An amount of the crosslinking agent below the above range causes a reduction of solvent resistance and injury resistance of the diazo-containing photosensitive layer. Too large an amount in excess of the above range causes lowering of the ammonia permeability, resulting in a reduction of development speed and in insufficient development. For reasons of solvent resistance, injury resistance and development efficiency of the diazo-containing photosensitive layer, it is preferred that the crosslinking agent be used in an amount of 10-100 parts by weight, more preferably 20-60 parts by weight, per 100 parts by weight of the cellulose ester.
Crosslinking of the cellulose ester with the lower-alkylated urea resin is based on an ether-forming reaction between the N-methylol groups contained in the lower-alkylated urea resin and hydroxyl groups contained in the cellulose ester.
In the present invention, an acid catalyst may be used to facilitate the crosslinking of the cellulose ester with the lower-alkylated urea resin. Examples of acid catalysts include citric acid, tartaric acid, sulfosalicylic acid and p-toluenesulfonic acid. Above all, the use of p-toluenesulfonic acid is preferred.
In the diazo compound of the formula shown above, the alkyl groups R
1
and R
2
may be a lower alkyl gro
Abiko Nobue
Maruyama Hiroshi
Suzukawa Yoko
Chu John S.
Lorusso & Loud
Somar Corporation
LandOfFree
Diazo-containing photosensitive material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Diazo-containing photosensitive material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Diazo-containing photosensitive material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2591410