Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Patent
1996-05-22
1998-10-13
Hamilton, Cynthia
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
430 18, 430311, 430330, 522103, 522101, G03F 740, G03F 738, G03F 7038, G03F 7028
Patent
active
058210318
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a photosensitive solder resist ink which is ultraviolet-curable and heat-curable and is capable of development with a dilute alkaline solution, a printed circuit board produced by using said resist ink, and a process for producing said printed circuit board.
BACKGROUND OF THE INVENTION
Changes have recently taken place in the process of forming resist patterns on printed circuits boards for domestic and industrial uses to cope with the ever-increasing wiring density on printed circuit boards. The conventional screen printing process is being replaced by the process based on dry film or photoresist ink on account of its good resolution and dimensional accuracy.
Among these resist inks, the photosensitive solder resist inks (which are generally called liquid photosensitive solder resist inks) are disclosed in Japanese Patent Publication No. 40329/1981 and Japanese Patent Laid-open No. 243869/1986. The first one is a composition containing as the essential ingredient an ultraviolet-curable resin formed by reaction of an unsaturated monocarboxylic acid with and simultaneous addition of a polybasic acid anhydride to an epoxy resin. The second one is capable of development with a dilute alkaline solution. It contains an ultraviolet-curable resin (soluble in a dilute alkaline solution) which is formed by addition of an acid anhydride to a novolak-type epoxy acrylate, a photopolymerization initiator, a diluent, and a thermosetting ingredient of epoxy compound.
Of the above-mentioned solder resist inks, the second one is used particularly for high-quality domestic and industrial products because, on curing with UV light and heating, it yields a solder resist having good physical properties.
As mentioned above, the solder resist ink contains an ultraviolet-curable resin and a thermosetting epoxy compound. The former contains carboxylic acids (originating from polybasic acid anhydride) in an amount sufficient for it to be developed with a dilute alkaline solution. The latter functions (by heat-curing) to react with the carboxyl group and increase the crosslink density of the solder resist, so that the resulting solder resist has good thermal and chemical stability and good resistance to soldering heat, chemicals, electrocorrosion, and gold plating.
To form a resist pattern on a board, the above-mentioned resist ink is applied to a board by dipping, spraying, spin coating, roll coating, curtain coating, or screen printing et al. The coating film of the resist ink is pre-cured at 60.degree.-120.degree. C. so as to evaporate the diluent (an organic solvent). The dried coating film is irradiated with UV light through a negative mask of desired pattern placed thereon directly or indirectly. (The source of UV light may be a chemical lamp, low-, medium-, high-, or ultrahigh-pressure mercury lamp, xenon lamp, or metal halide lamp.) After irradiation, the resist film undergoes development so that a desired pattern is formed. Finally, the resist film is heated at 120.degree.-180.degree. C. for about 30 minutes so as to cure the epoxy compound. This curing improves the resist film in strength, hardness, and chemical resistance.
The pre-curing is an important step which makes the coating layer of the resist ink non-sticky, thereby permitting the negative mask to be mounted and demounted and protecting it from staining. In the case where the resist ink contains an epoxy compound, the pre-curing also heat-cures the epoxy compound through the reaction with the carboxyl group present in the ultraviolet-curable resin. This leads to poor development and poor resolution. This trouble is liable to occur in the case where the epoxy compound is a general-purpose solvent-soluble epoxy resin. Therefore, the pre-curing has to be carried out under mild conditions, say, at 80.degree. C. for 30 minutes or less (preferably 20 minutes or less). (In the following, the term "pre-curing latitude" is used to denote the pre-curing conditions necessary for good development and resolution.)
A p
REFERENCES:
patent: 4933259 (1990-06-01), Chihara et al.
patent: 5539064 (1996-07-01), Hashimoto et al.
Hashimoto et al, 122:42784, Chemical Abstracts, American Chemical Society, English Abstract of JP 06 258830, published 16 Sep. 1994.
Hashimoto et al, 06-258830, Patent Abstract of Japan, English Abstract of JP 06-258830 published 16 Sep. 1994.
Hashimoto et al, 94-335827, World Patents Index, Derwent Information Ltd, English Abstract of JP 06-258830 published 16 Sep. 1994.
Hashimoto Soichi
Oda Toshikazu
Suzuki Fumito
Goo Chemical Co., Ltd.
Hamilton Cynthia
LandOfFree
Photosensitive solder resist ink, printed circuit board and prod does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Photosensitive solder resist ink, printed circuit board and prod, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photosensitive solder resist ink, printed circuit board and prod will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-312016