manufactured. As such, the fine metal film having various patterns is applied in a variety of fields including current-carrying circuits of semiconductors and electronic devices.

Background Art In general, a fine metal pattern has been manufactured by means of an etching process. However, in the present invention, an electro-forming process is adopted, and thus, an electro-formed product that is to be a pattern is composed of a thin film structure of a layered heterogeneous metal.

In addition, the electro-forming process is suitable for use in production of a thin film structure of a homogeneous or heterogeneous metal, and, particularly, may be employed for manufacturing an electro-formed product patterned by layering the above thin film structure. As such, the thin film structure has a thickness of ones of to tens of ; jm. In some cases, several hundreds of psm of a metal film may be formed.

In the present invention, the electro-formed product having a complicated shape means that the shape of the cross section thereof is different in a thickness direction, that is, in a height direction. Such an electro-formed product results from the use of the electro-formed master obtained by changing a size and a position of an exposure part to be prepared through an exposing film. That is, the size and the

position of the exposure part are slightly changed, whereby a pin part formed of an insulating material and protruding from a surface of an electrode base has a cross section of a shape changed in a height direction thereof. Eventually, the electro-formed product, resulting from the electro-forming process in the electro-forming bath, has cross sections of various shapes in a height direction thereof.

Disclosure of the Invention A fine film structure of metal pattern, constituting current-carrying circuits, has been conventionally manufactured by means of an etching process. However, the etching process, acting to corrode a metal, has a limitation in accuracy. This is because the etching process causes the metal to corrode in a lateral direction as well as a downward direction. Hence, it is difficult to ensure a dimensional accuracy in a lateral direction. Further, the etching process has the limitation of processable pitches and heights, due to lateral corrosion. Also, the etching process is disadvantageous in that the corroded amount of the metal must be discarded.

However, in the present invention, an electro-forming process is adopted to manufacture a more accurate metal pattern, instead of the etching process. That is, a metal is allowed to form in only a defined range by a pin part of an

electro-forming master used for the electro-forming process, whereby lateral corrosion of the etching process is not caused. Hence, fine pitches can be processed. Additionally, the electro-forming process of the present invention is characterized in that the electro-forming master includes only materials necessary for production of the fine metal pattern, and thus, there is no waste of materials. Also, the electro-forming process enables end products to be simply manufactured, compared to conventional processes. That is, although every product should be conventionally subjected to being exposed to light and etching, the inventive electro- forming process does not need such steps and allows end products to be repeatedly produced by use of the electro- forming master in the electro-forming bath.

Of course, the fine metal pattern has been conventionally manufactured by an electro-forming process.

However, an electro-forming master used for the conventional electro-forming process suffers from a single application.

Otherwise, a hard resister is formed on an electrode base, and therefore, the electro-forming master may be reused.

However, since the hard resister creates stress between an electro-formed product and the resister, when the electro- formed product is released from the resister, such stress prevents the release of the electro-formed product from the resister. That is, the electro-formed product and the resister are mutually interacted, due to the stress, upon the

removal of the electro-formed product from the electro- forming master, whereby they may be damaged by each other.

Hence, a conventional electro-forming process cannot be repeatedly performed. Whereas, an elastic pin part of the present invention is applied to manufacture an electro- forming master, instead of the hard resister, whereby the elastic pin part has no influence on the electro-formed product upon release. Accordingly, such an electro-forming master enables the electro-formed product to be easily released therefrom, and can be reused.

On the other hand, a conventional electro-formed product cannot but have a limited height by the condition of a photosensitive material to be used. In contrast, the pin part of the present invention can increase in height as desired, whereby the electro-formed product has a desired height. Further, although the conventional electro-formed product has only a cross section of a quadrangular shape, the electro-formed product of the present invention can have a stepped-cross section or a curved-cross section, which is possible by preparing the pin part of the electro- forming master having shapes complementary to various three-dimensional shapes of the electro-formed product.

Therefore, it is an object of the present invention to alleviate the problems in the related art and to provide an electro-forming master having a complicated shape.

Another object of the'present invention is to provide

a method of manufacturing the electro-forming master.

Still another object of the present invention is to provide an electro-formed product having a complicated shape, manufactured by use of the electro-forming master.

To accomplish the above objects, the'present invention provides an electro-forming master including an electrode base on which a current-carrying part having a shape identical to that of a fine metal pattern and an insulating part formed of an insulating material are formed. The insulating part, acting as a pin part protruding from a surface of the electrode base, is used to control a shape of a metal to be electro-formed. A height of the pin part can increase by layering an exposure part of a photosensitive material and an insulating part. As such, the present invention is characterized in that the exposure part and the insulating part are alternately layered. When the pin part reaches a desired height, the layered exposure part is selectively removed from the electrode base while leaving the insulating part. Moreover, the pin part has a cross section of a shape changed in a height direction thereof.

Brief Description of the Drawings The above and other objects, features and other advantages of the present invention will be more clearly

understood from the following detailed description taken in conjunction with the accompanying drawings, in which : FIG. 1 is a view schematically showing a fine metal pattern; FIG. 2 is a view showing an electro-forming process to be performed by immersing an electro-forming master into an electro-forming bath; FIG. 3 is a view sequentially showing a process of preparing a first insulating part on an electrode base having a root part, in an electro-forming master according to a first embodiment of the present invention; FIG. 4 is a view sequentially showing a process of preparing a second insulating part on the electrode base having the root part; FIG. 5 is a view sequentially showing a process of preparing a third insulating part on the electrode base having the root part; FIG. 6 is a view sequentially showing a process of preparing a first insulating part and a second insulating part on an electrode base having no root part, in an electro-forming master according to a second embodiment of the present invention ; FIG. 7 is a view sequentially showing a process of preparing a third insulating part on the electrode base having no root part ; FIG. 8 is a view showing a process of releasing an

electro-formed product from the electro-forming master; FIGS. 9 and 10 are views showing electro-formed products with complicated shapes, each of which is composed of different types of metals; and FIG. 11 is a view showing an electro-formed product of the present invention which is applied to a gear having a stepped-cross section of different types of metals.

Best Mode for Carrying Out the Invention Based on the present invention, there are provided an electro-forming master having a complicated shape, and a manufacturing method thereof. In addition, an electro- formed product having a complicated shape is provided by use of the electro-forming master. As for the electro- forming master of the present invention, an electrode base is prepared, on which an insulating part acting to prevent a current from flowing and a current-carrying part having a shape identical to that of an electro-formed product are formed.

Further, the electrode base of the present invention has an insulating part and an exposure part formed thereon.

As such, the insulating part and the exposure part increase in height by alternately layering them. Then, only the exposure part is selectively removed from the electrode base having the insulating part and the exposure part. For

this, heat or a laser is used to remove the exposure part from the electrode base, provided that the insulating part should not be damaged. On the other hand, a space formed by removing the exposure part from the electrode base is to be a depression part, through which the surface of the electrode base is bared. The bared surface of the electrode base comes to be a current-carrying part of the electro-forming master of the present invention, in which the current-carrying part has a shape same as the electro- formed product, such as a fine metal pattern. In the present invention, when a plurality of exposure parts are formed, sizes and positions of the exposure parts are slightly changed by means of a plurality of exposing films, whereby the insulating part has a cross section of a shape changed in a height direction thereof.

After only the exposure part is selectively removed from the electrode base having the exposure part and the insulating part, the remaining insulating part functions as a pin part. Further, a recess of the electrode base is formed at a lower portion of the pin part and is filled with an insulating material to be a root part, which is integrally formed with the pin part. The recess of the electrode base is formed through an etching process or a mechanical process or a laser process.

Further, the electro-forming master of the present invention is classified into two types according to the

presence of the recess on the electrode base. As for the electro-forming master having the recess, the recess is formed at an upper portion of the electrode base, and is filled with insulating material to be the root part. In addition, the pin part is integrally formed on an upper portion of the root part and protrudes from the surface of the electrode base. In the present invention, the insulating part protruding from the surface of the electrode base is defined as the pin part, and the insulating material under the pin part is defined as the root part.

The root part functions to firmly couple the pin part to the electrode base. The pin part functions to limit the shape of the metal to be electro-formed to a predetermined shape. That is, since the electro-formed product is shaped according to the shape of the pin part, the pin part largely affects the shape of the electro-formed product.

Meanwhile, a resister used for a conventional electro- forming process allows a shape of an electro-formed product to be formed in a quadrangle in a vertical direction of the electro-formed product, that is, a thickness direction thereof. Hence, a conventional electro-formed product has a simple cross section.

However, the present invention is characterized in that the pin part is prepared so that the electro-formed product has various shapes, including simple quadrangular

shapes as well as complicated three-dimensional shapes, in a thickness direction thereof. It is natural that the electro-formed product has a simple quadrangular cross section when the plurality of exposure parts are stacked in the same positions and shapes. In addition, the electro- formed product may have a plurality of metal layers having different properties.

Moreover, the pin part has a great influence on the thickness of the electro-formed product, in addition to the shape thereof. Commonly, the thickness of the electro- formed product is limited by the height of the resister.

When the electro-formed product needs to have a predetermined thickness, although the resister should have a height suitable for the thickness of the electro-formed product, it is impossible to practically prepare the resister having a predetermined thickness or more, due to preparation technical limitations of the resister.

Therefore, it is difficult to produce an electro-formed product having a predetermined height or more through a conventional electro-forming process. However, in the present invention, the pin part can increase in height as necessary by layering the exposure part and the insulating part on the electrode base.

As well, the pin part formed of the insulating material has preferably elasticity, which is exemplified by silicone. More preferably, the insulating material of the

present invention has insulation, elasticity and releasability. Further, such an insulating material has high adhesion to be easily coupled to the electrode base.

The adhesive silicone material may meet the above requirements of the present invention. That is, the insulating material composed mainly of silicone has high insulation, releasability and elasticity, in which it means that it has silicone in mixture with various additives, on occasion demands.

Hence, the use of the elastic insulating material constituting the pin part leads to the preparation of reusable electro-forming master, and also, easy release of the electro-formed product from the electro-forming master, by reason of elasticity of the pin part. Thereby, the pin part and the electro-formed product are never damaged. In particular, the electro-forming master of the present invention is advantageous in terms of reusability thereof.

Reference should now be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.

FIG. 1 is a schematic view showing a fine metal pattern, which is a metal pattern 100 having very fine patterns. Such a metal pattern, which is variously applied in the fields of semiconductors or fine current-carrying circuits, is produced by use of an exposing film with a

transparent portion and an opaque portion. The film has a variety of patterns by means of the transparent portion and the opaque portion. In the present invention, the above film is used to prepare a patterned electrode base, which is then employed to manufacture an electro-forming master capable of repeatedly producing the fine metal pattern.

The present invention is characterized in that the fine metal pattern can be mass produced by use of the inventive electro-forming master.

FIG. 2 illustrates an electro-forming process to be performed by immersing an electro-forming master of the present invention into an electro-forming bath. As apparent from FIG. 2, an electrode base 5 is connected with a negative electrode (-) to perform the electro-forming process in the electro-forming bath. Thereby, an ionized metal begins to be formed on the electrode base 5, to produce a fine pattern of thin metal. When the electro- forming process is carried out on the electrode base in the electro-forming bath, a metal ion is formed on the surface of the electrode base bared between insulating parts 200 over time, hence obtaining a metal layer flush with the insulating part.

FIG. 3 is a view sequentially showing the preparation process of a first insulating part on an electrode base having a root part, in an electro-forming master according to a first embodiment of the present invention. As seen in

FIG. 3, a photosensitive material 2 is coated on an electrode base 101, after which a film having a predetermined pattern is exposed to light to prepare a first exposure part 3. Also, a non-exposure part, prepared together with the first exposure part, is washed and formed to be a depression part, which is then subjected to etching to form a recess 4 in a predetermined depth of an upper portion of the electrode base. Like this, the electrode base having the recess 4 is referred to as a recess-formed electrode base 1 in the first embodiment of the present invention. Alternatively, the recess of the electrode base may be formed through a mechanical process or a laser process. Thereafter, an insulating material 6 is filled in the recess 4 of the electrode base, and trimmed to be flush with the first exposure part 3 and then hardened to form a first insulating part 7. The insulating material filled in the recess under the first insulating part 7 is to be a root part 6.

FIG. 4 is a view sequentially showing the preparation process of a second insulating part on the electrode base having the recess. As shown in FIG. 4, after the insulating material of FIG. 3 is hardened, a photosensitive material 8 is further coated on the all surfaces of the first insulating part and the first exposure part of the electrode base. Then, a film having a pattern slightly different from that of the film used for the formation of

the first insulating part is exposed to light, to prepare a second exposure part 9. A non-exposure part, prepared together with the second exposure part, is washed and formed to be a depression part 10, which is then filled with an insulating material to obtain a second insulating part 11. As such, the used insulating material is adhesive, and thus, easily adheres to the lower insulating material.

Subsequently, the second insulating part is trimmed to be flush with the second exposure part, and then hardened. In the present invention, the adhesive insulating material is exemplified by silicone.

FIG. 5 is a view sequentially showing the preparation process of a third insulating part on the electrode base having the recess, thereby obtaining the electro-forming master according to the first embodiment of the present invention. As illustrated in FIG. 5, after the insulating material of FIG. 4 is hardened, a photosensitive material 12 is further coated on the all surfaces of the second insulating part and the second exposure part of the electrode base. Subsequently, a film having a pattern slightly different from that of the film used for the formation of the second insulating part is exposed to light to prepare a third exposure part 14. A non-exposure part, prepared together with the third exposure part, is washed and formed to be a depression part 13, which is then filled with an insulating material to obtain a third insulating

part 15.

By repeating the above procedure, when the layered insulating part reaches a desired height, the stacked exposure part is removed from the electrode base, thus resulting in a desired pin part. As such, it should be noted that only the exposure parts are removed from the electrode base in the state of the exposure parts and the insulating parts being stacked together on the electrode base. In the cases where a low pin part is required, the exposure part may be selectively removed from the electrode base in the state of the first insulating part being formed.

With the intention of selective removal of the exposure part, the photosensitive material acting to easily remove the exposure part by heat may be used, or only the exposure part may be selectively removed with a laser. Particularly, a color reacting with the laser light is contained in the exposure part, whereby only the exposure part may be selectively removed. Through other different methods, only the exposure part is removed from the electrode base while the insulating part is not damaged. The insulating part which remains on the electrode base 5 after the removal of the exposure part functions as a pin part 16. The recess of the electrode base is formed to be a root part, and the pin part is integrally formed on an upper portion of the root part and protrudes from the surface of the electrode base. The shape and height of the pin part functions to

determine the shape and thickness of the fine metal pattern, respectively. Although a thick exposure part cannot be formed at a time by use of a typical photosensitive material, the high pin part can be formed through the above process of the present invention, which is regarded to be important.

Turning to FIG. 6, there is sequentially illustrated the preparation process of first and second insulating parts on an electrode base having no root part, in an electro-forming master according to a second embodiment of the present invention. That is, the root part is not formed, and first and second exposure parts and first and second insulating parts are formed on the electrode base.

As illustrated in FIG. 6, a photosensitive material 19 is coated on a flat electrode base 17, after which a first film is exposed to light, to prepare a first exposure part 20 and a non-exposure part. The non-exposure part is washed and formed to be a depression part 21, which is then filled with an insulating material to obtain a first insulating part 22. As such, the used insulating material is adhesive, and thus, is easily attached to the electrode base which is positioned at a lower portion thereof. The first insulating part is trimmed to be flush with the first exposure part and then hardened.

Thereafter, the photosensitive material is further coated on the all surfaces of the first insulating part and

the first exposure part of the electrode base, after which a second film is exposed to light, to prepare a second exposure part 23 and a non-exposure part. The non-exposure part is washed and formed to be a depression part 24, which is then filled with an insulating material to form a second insulating part 25. As such, the used insulating material has adhesion, and thus, is easily attached to the lower insulating material. The second insulating part is trimmed to be flush with the second exposure part and then hardened.

FIG. 7 is a view sequentially showing the preparation process of a third insulating part on the electrode base, thereby obtaining the electro-forming master according to the second embodiment of the present invention. As shown in FIG. 7, the photosensitive material is further coated on the all surfaces of the first and second exposure parts and the first and second insulating parts of the electrode base having no root part. Subsequently, a third film is exposed to light, resulting in a third exposure part 26 and a non- exposure part. The non-exposure part is washed and formed to be a depression part 27, after which an insulating material is filled in the depression part to obtain a third insulating part 28. The third insulating part is trimmed to be flush with the third exposure part and then hardened.

The cross section of the electro-formed product having a complicated shape of the present invention is different in a height direction thereof. For example, the

electro-formed product may have a curved-cross section or a stepped-cross section. The production of the electro- formed product having complicated shape in a height direction thereof through the electro-forming process in the electro-forming bath becomes possible by preparing a plurality of exposure parts having different shapes through the exposing process. As such, the exposing process utilizes the first film, the second film, and the third film, each of which has a slightly different pattern.

Thereby, the stacked exposure part having a changed cross section can serve to make the layered insulating part, which comes to be the pin part of the electro-forming master of the present invention. In the present invention, the stacking number of the exposure part increases, and the height of the exposure part to be stacked becomes low, thus obtaining the electro-formed product with a softer curved shape.

Then, the stacked exposure parts 20,23 and 26 are selectively removed from the electrode base as in FIG. 5, resulting in an electro-forming master having a pin part 29 on the electrode base 18.

FIG. 8 is a view showing the releasing process of the electro-formed product from the electrode base. As shown in FIG. 8, when an electro-formed product 30 reaches a desired height by use of the electro-forming master through the electro-forming process, it is released from the

electrode base 5. The resultant electro-formed product has a shape complementary to that of the pin part 16 protruding from the surface of the electrode base 5.

FIG. 10 is a view showing an electro-formed product having different types of metal layers. As apparent from the drawing, the electro-formed product 30 has metal layers of copper, nickel and copper, in order, by sequentially immersing the electro-forming master into electro-forming baths each having different types of metals through the electro-forming process. Thereby, the electro-formed product having heterogeneous metals can result. In the present invention, the electro-formed product having a complicated shape can increase in height by layering the different types of metals, and can have a predetermined pattern by changing the shapes of the exposure parts according to the patterns of the exposing films.

FIG. 11 shows a gear, which has a stepped-cross section of different types. of metals, as an application of an electro-formed product of the present invention. As seen in FIG. 11, a pin part formed of an insulating material 32 which mainly includes silicone is provided on an electrode base 31, by which gears 33 and 34 are shaped on the electrode base. As such, the gear is obtained by layering three types of metals of nickel, copper and nickel, and has a height of ones of to tens of pm and an outer diameter of tens of pm. Hence, such an electro-formed

product can be variously produced on a large scale.

In the present invention, the electrode base and the insulating material are made of various materials. For example, the electrode base is made of stainless steel, which has superior durability and functions to easily release a finely patterned electro-formed product of thin metal, such as copper or nickel, from the electro-forming master. Further, the insulating material has elasticity.

Thereby, such an insulating material does not generate stress with the electro-formed product resulting from the electro-forming process, thus easily performing the releasing process. In addition, upon the releasing process, the electro-formed product and the insulating material are not damaged by each other. Therefore, it is preferred that the insulating material is elastic, which is exemplified by silicone. When such a silicone insulating material having elasticity and releasability at the same time is used, it is not damaged upon releasing the electro-formed product of thin metal pattern from the electro-forming master. Also, silicone having high releasability acts to easily separate such an electro-formed product from the electro-forming master.

Industrial Applicability As described above, the present invention provides an

electro-forming master having a complicated shape, a method of manufacturing the same, and an electro-formed product manufactured using the same, characterized in that the electro-forming master can be reused by means of a pin part having elasticity. Upon releasing the electro-formed product from the electro-forming master, the elastic pin part has no influence on the electro-formed product. Thus, the electro-forming master prevents the pin part and the electro-formed product from damaging upon the releasing process, and is reusable.

Moreover, although a conventional electro-formed product cannot but have a limited height by the condition of a photosensitive material to be used, the pin part of the present invention can increase in height as desired, whereby the electro-formed product has a desired height-.

Further, the conventional electro-formed product has only a cross section of a quadrangular shape, whereas the electro- formed product of the present invention can have a stepped- cross section or a curved-cross section. That is, the pin part of the electro-forming master of the present invention is prepared to have three-dimensional shapes, and hence, the resulting electro-formed product has cross sections of shapes complementary to those of the pin part.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.