Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Reexamination Certificate
1999-08-18
2002-05-07
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
C430S314000, C430S319000
Reexamination Certificate
active
06383720
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of manufacturing fine pattern, and a printed circuit board manufactured by using this method. In particular, the invention relates to a method of manufacturing fine pattern suitable for use as an etching mask and a plating mask in manufacturing a printed circuit board, and a printed circuit board manufactured by using the fine pattern. The fine pattern is used when manufacturing fine line and high density printed circuit boards, multi-layered printed circuit boards, flexible printed circuit boards and the like which are incorporated into semiconductor packaging such as IC cards, and electronic equipment such as portable information terminals.
BACKGROUND OF THE INVENTION
The conventional method of manufacturing a print circuit board (hereinafter referred to as “PCB”) includes a subtracting method, in which circuit conductors are formed by making up a predetermined insulating pattern over a copper foil on a surface of a copper clad laminate, followed by removal of any unnecessary portion of the copper foil with an etching process. Another method of manufacturing a PCB, among others, is an additive method, in which circuit conductors are formed by applying a catalyzer over a surface of an insulation substrate, followed by formation of a predetermined insulating pattern, and an electroless copper plating.
On the other hand, photolithography is one method of forming an insulating fine pattern on a substrate surface, by applying a photosensitive resist on the substrate, exposing, and developing it. This method is used commonly in the method contains a complicated manufacturing process, since it requires an application and exposure of photosensitive resist for every layer of circuits. Also, the products manufactured by the photolithography method have been expensive, because various kinds of equipment are used. For example, necessary equipment for exposure of ultraviolet rays to the photoresist is expensive.
On the other hand, there are printing methods for forming a fine pattern directly on a substrate, as means of forming the insulating fine pattern in a shape of circuits on the substrate at lower cost. Although there are such printing methods as offset printing, screen printing, and the like methods, it is not feasible to form a pattern of 100 &mgr;m or less in width with any of these methods in mass-production. In addition, the printing methods are not suitable for making a pattern of high definition, since they are not considered satisfiable in respect of reproducibility.
Therefore, the photolithography, which is superior in quality, even though it is more costly, has been utilized principally in order to satisfy a demand for PCB's of thinner film, higher density and increased layers with the latest progress of semiconductors requiring higher operating frequencies, and electronic devices for downsizing and greater integration.
Under the situation as described, a new method has been desired for forming fine pattern with a simple process and economically low cost, while maintaining high quality. Several methods have been devised in attempting to improve preciseness while also obtaining a simplification and low cost in the manufacturing process of forming fine pattern. Some of the methods will be described hereinafter.
According to the teaching of Japanese Patent Laid-Open Publication, Number S63-266482, a method is suggested, in that a fine pattern film in high precision is formed first on a master substrate. A fine pattern film is then transferred onto another substrate. The above method of forming fine pattern is utilized for manufacturing a color filter. In the manufacturing, it uses an insulating master substrate having an electrode corresponding to a shape of the color filter on its surface. A fine pattern film made of resin is formed by electro-depositing the resin on the electrodes corresponding to each color of the master substrate. The fine pattern film is then tightly pressed onto another substrate, to exfoliate and transfer the fine pattern film onto the substrate by making full use of the electro-deposited resin's own tackiness. This method is superior in economical standpoint, because the master substrate can be used repeatedly, thereby eliminating an exposure operation for each PCB during the process of forming the fine pattern film. However, the fine pattern film has a weak adhesion to the substrate being transferred, since the exfoliation and transference is made only by the electro-deposited resin's own tackiness. At the same time, it has a shortcoming in that a full transference cannot be made reliably due to a strong adhesion of the fine pattern film to the master substrate.
Also, there is a kind of master substrate for forming fine pattern, as disclosed in Japanese Patent Laid-Open Publication, Number H06-301198, as an example. It discloses a method in which a layer of photo-resist in a shape of fine pattern is formed on a thermally oxidizable metal plate such as stainless steel, titanium and tantalum, or a nitridable metal plate such as titanium and silicon. An insulating pattern-masking layer composed of oxide film or nitride film is then formed by thermally oxidizing or nitriding a portion not covered by the layer of photo-resist. The metal plate produced in the above step is used as a master substrate for forming the fine pattern. The insulating pattern-masking layer has a strong adhesion to the master substrate, since the insulating pattern-masking layer is produced from the thermally oxidizable metal plate or the nitridable metal plate. There have been problems even with this master substrate, such as deterioration of a fine pattern film, low in yield, and a short usable life of the master substrate. The fine pattern film needs to be separated forcedly in order to totally exfoliate and transfer the film due to the strong adhesion of the film to the master substrate.
On the other hand, the inventors of this application have devised and disclosed in Japanese Patent Laid-Open Publication, Number H09-272345, a method of manufacturing fine pattern, which weakens adhesion of a fine pattern film made of electro-deposited resin to a master substrate, thereby enabling complete exfoliation and transference of the film. The method disclosed by the inventors uses a master substrate having a pattern electrode layer in a predetermined shape on the substrate, and an exfoliation layer composed of a thin water repellent film formed on the master substrate. Furthermore, a fine pattern film is formed on the master substrate by electro-depositing, and the film is hydrated with hot water in temperature of not less than 40° C. but not more than 90° C. The hydration, i.e. impregnation of water, of the fine pattern film can weaken adhesion due to water repellency of the exfoliation layer on a surface of the master substrate. In addition, a surface of the fine pattern film is warmed so as to turn it into a state of tackiness. Therefore, the above method is able to exfoliate and transfer the fine pattern film completely onto a substrate subject to be transferred.
The method of forming fine pattern, as described above, is to form a fine pattern film on a master substrate with electro-depositing, and to exfoliate and transfer the film onto a substrate subject to be transferred. This method is able to form the fine pattern film of high quality, if the master substrate is precisely made. The method is also capable of producing the fine pattern film easily at low cost with quite a simple process, since it does not require use of photolithography for each of every formation of the fine pattern, and it can allow repeated use of the same master substrate.
However, there are two types of electro-depositing, anion type and cation type depending on electric charge of the ionic radical introduced into an electro-deposited resin. In the case of utilizing an electro-deposited film for forming a fine pattern as disclosed in the above-cited invention, an anion type electro-deposition is suitable in order to avoid min
Kamizuru Shinobu
Nakashima Koji
Yoshino Toyokazu
Gilmore Barbara
Matsushita Electric - Industrial Co., Ltd.
Parkhurst & Wendel L.L.P
LandOfFree
Method of manufacturing fine pattern and printed circuit... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of manufacturing fine pattern and printed circuit..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing fine pattern and printed circuit... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2886887