BACKGROUND ART In the present invention, mass production of an ultrafine pipe can be achieved without any ultra precise mechanical process. The ultra precise mechanical process required for an ultra precise diameter takes time and causes high cost. It is difficult to mechanically process

the inner diameter of the ultrafine pipe having several microns in practical aspect. However, in the present invention, the inner and outer diameters of the ultrafine pipe can be obtained by moving metal ions. Also, multi- layered metal layers constituting the pipe can be formed.

There has been a conventional method for manufacturing an ultrafine pipe by an electroforming process. That is, an electroforming process for forming an inner diameter of a pipe using a core material is well known. In the conventional method, a longitudinal metal rod is manufactured by performing an electroforming process in a core material of a longitudinal metal, and the core material in the longitudinal metal rod is physically drawn to form a through hole in the pipe. The conventional method is similar to the present invention in that the pipe is manufactured by the electroforming process based on the core material. However, the present invention is different from the conventional method in that the core material is drawn without damaging the inner diameter of the ultrafine pipe. The present invention is characterized in that a special forming material is covered in the core material and the core material is easily drawn from the electroformed ultrafine pipe.

DISCLOSURE OF THE INVENTION Accordingly, the present invention is directed to an ultrafine pipe and a method for manufacturing the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide an ultrafine pipe and a method for manufacturing the same, in which the ultrafine pipe is made by performing an electroforming process in an electroforming tub.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the scheme particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a method for manufacturing an ultrafine pipe by an electroforming process includes the steps of covering a core material passing through a die with a forming material existing at a melted state or partially melted state in the die, thinly coating the forming material with a conductive material after it is hardened, forming an electroforming layer by connecting a negative electrode to the conductive coating portion and performing the electroforming process in an electroforming tub, removing the core material existing in the electroforming layer by a drawing process, and washing the inside of the pipe. The forming material is softened at a temperature of 100°C or less, or is contracted with the lapse of time to remove the core material. The forming material includes resin and a low temperature heat melting material. The low temperature heat melting material is softened at a temperature of 100°C or less. The low temperature heat melting material includes at least one of resin, pitch and wax. The resin is thermoplastic or thermosetting resin. An example of the resin includes epoxy resin. A small content of silicon may be added to the forming material to improve hetero-characteristics.

The coated conductive material is thinly formed on the

forming material by vacuum deposition. The coated conductive material is thinly deposited on the forming material by a chemical method.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

In the drawings: FIG. 1 illustrates an electroforming process according to the present invention; FIG. 2 is an example of an ultrafine pipe; FIG. 3 illustrates a covering process of a forming material and a coating process of a conductive material; FIG. 4 illustrates a pipe manufactured by forming an electroforming layer on a conductive metal coating layer; FIG. 5 illustrates a process of removing a core material from an ultrafine pipe; FIG. 6 illustrates the state that a forming material and a conductive material are chemically removed from the pipe ; and FIG. 7 illustrates a pipe formed of different kinds of metal layers.

BEST MODE FOR CARRYING OUT THE INVENTION Reference will now be made in detail to the

preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

An ultrafine pipe is widely used in a semiconductor test device or ultra precise parts. Since the ultrafine pipe used in the semiconductor test device has a sliding pin therein, processing precision and illumination are very important. In the semiconductor test device, the ultrafine pipe requires excellent conductivity. The ultrafine pipe made by the electroforming process of the present invention can reduce processing error in the range of several microns or less and has excellent surface illumination. Also, since a pipe of different kinds of metals can be manufactured, the intensity and conductivity of current can preferably be obtained.

FIG. 1 illustrates an electroforming process according to the present invention. A metal ion melting solution 300 decomposed in ion state is contained in an electroforming tub 400. An electroforming metal case 100 of nickel, for example, is positioned at one side of the electroforming tub. A positive electrode is connected with the electroforming metal case and a negative electrode is connected with a conductive material 200 to be electroformed. The metal ion decomposed by electricity moves to the surface of a target having conductivity and is grown as a new electroforming metal layer on the surface of the conductive material. This process is called an electroforming process. In the present invention, nickel, copper (Cu), gold (Au), or nickel (Ni) alloy is used as the metal used for electroforming. Other metal that can be electroformed may be used as the metal for electroforming.

FIG. 2 is an example of an ultrafine pipe. An ultrafine pipe 600 has an outer diameter of several

microns to several hundreds of microns. A slider 500 of pin is formed inside the ultrafine pipe and performs sliding movement. It is important that the ultrafine pipe has an inner diameter having processing precision. A conductive metal coating layer having excellent conductivity is required in the inner diameter as the case may be. The conductive metal coating layer may be used to check current characteristic value.

FIG. 3 illustrates a covering process of a forming material and a coating process of a conductive material.

It is general that a core material 1 used to manufacture the ultrafine pipe of the present invention has the size of several microns or several tens of microns. The core material is produced by drawing or extrusion. The core material processed by drawing or extrusion has limitation in its cylindrical degree. A number of scratches are generated on the surface of the core material. In the present invention, the core material 1 is covered with a melted or partially melted forming material 2, so that the scratches and the incomplete cylindrical degree minimize any effect on the inner diameter of the ultrafine pipe.

That is, a die 3 is supplied with the forming material 2, and the core material 1 is drawn and at the same time is covered with the forming material at a uniform shape and size. The forming material is supplied into the die at the melted state or the partially melted state. The forming material serves to cover damage formed on the core material. The forming material passed through the die 3 has a supplemented cylindrical degree like the shape of the die 3. If the die has a circular shape, the core material is covered with the forming material having a circular shape. If the die has a rectangular shape, the core material is covered with the forming material having

a rectangular shape.

In the present invention, it is preferable that the forming material is softened by heat if it is hardened on the surface of the core material or the forming material is automatically contracted after the lapse of time if it is hardened on the surface of the core material. An example of the forming material includes mixture of resin and a low temperature heat melting material. In the experiment example, the forming material has been formed by mixing epoxy resin of 60%, resin of 20% as a heat melting material, and silicon of 20% for improving hetero- characteristics. If the core material has a thickness of 50 microns, it can easily be drawn without applying heat.

If the core material has a thickness of 150 microns, it can be drawn by applying heat at a temperature of 100°C or less. If the core material has a thin thickness, it is easily removed without applying heat after the lapse of time. This is because that the forming material is automatically contracted with the lapse of time after it is hardened. In the present invention, a low temperature heat melting material such as pitch or wax may be used instead of resin. The low temperature heat melting material may be made by selectively mixing resin, pitch, and wax. Silicon has been used to increase hetero- characteristics. In the present invention, the forming material has been made by mixing resin of various materials with a heat melting material of various materials. The core material can be covered with the forming material having different characteristics and the forming material can remove the core material. In this respect, the present invention is not limited to the experiment value of epoxy resin of 60%, resin of 20%, and silicon of 20%. That is, the present invention is not

limited to kinds and ratio of mixture.

In the present invention, the core material 1 has a thickness of several microns-or several tens of microns, and the core material of metal or non-metal may be used.

The core material of metal is preferably used because strong tension is required for the core material. An example of the metal core material includes stainless steel. The core material made by a mechanical method has some problems such as defects and scratches caused on its surface and uneven thickness. If the electroforming process is performed in the original core material without covering damage on the surface of the core material with the forming material, the surface roughness of the core material is reflected on the inside of the electroformed pipe and the core material is engaged with the scratches of the pipe. In this case, it is very difficult to remove the core material. However, in the present invention, the core material is uniformly covered with the forming material while being passed through the die. As a result, the scratches on the surface of the core material are all covered with the forming material. The inside of the ultrafine pipe according to the present invention is precisely controlled in its dimensions because the die can be controlled in ultra precision. In the present invention, the forming material is used to minimize poor effect of the core material by covering the core material and to easily remove the core material after the ultrafine pipe is formed by the electroforming process. Since the core material is covered with the forming material of the present invention, the core material is separated from the inner diameter of the electroformed ultrafine pipe. In the present invention, when the core material is covered with the forming material, it is preferable that the core

material is uniformly covered with the forming material with concentricity while passing through the center of the die.

After the core material is covered with the forming material and the forming material is hardened, the forming material is thinly coated with a conductive material. A conductive metal coating layer 4 may thinly be formed on the forming material by vacuum deposition or chemical method. The chemical method means that a metal film is formed by a chemical reaction that extracts chemical silver (Ag) or platinum. In the present invention, various metals such as gold, silver, copper or nickel may be used as the conductive metal. The conductive metal coating layer 4 is coated on the forming material 2 and serves as a conductor that serves to flow negative current during the electroforming process.

FIG. 4 illustrates a pipe manufactured by forming an electroforming layer on the conductive metal coating layer.

An electroforming layer 5 serves as a main body of the ultrafine pipe of the present invention and is formed of electroforming metal such as nickel, nickel alloy or copper. Also, the electroforming layer 5 may be formed by layering different kinds of metals. To form the electroforming layer, melted metal ions move to the conductive metal coating layer by connecting negative electrode to the conductive coating layer and positive electrode to the electroforming metal. The moving metal ions start to be formed as an electroforming metal film on the surface of the conductive metal coating layer. The thickness of the electroforming metal film is grown with the lapse of time. As a result, the electroforming layer 5 is formed. The thickness of the electroforming layer is within the range of several microns to several tens of

microns or several hundreds of microns. The thickness of the electroforming layer may be within the range of several millimeters.

FIG. 5 illustrates the process of removing the core material from the ultrafine pipe. The core material is removed by a drawing process to obtain the ultrafine pipe 5 having a through hole inside the pipe after the electroforming process is performed. In this case, the core material is not easily removed because it is thin. In the present invention, the forming material 2 coated on the surface of the core material is varied to a fluid state by heat to easily remove the core material. If the electroforming process is directly performed in the rough core material, it is difficult to remove the core material because the scratches of the core material are engaged with those inside the electroformed pipe. Also, there is limitation in improving precision because the scratches of the core material are reflected inside the pipe as they are. If the core material is physically drawn from the electroforming member, it may be likely to be cut during the drawing process. The inner wall of the ultrafine pipe is damaged when the core material is drawn. This makes the precise process difficult. In this case, the precise mechanical process is again performed to cover the damage of the inner wall of the ultrafine pipe. In the present invention, fluidity is given to the forming material 2 by heating the ultrafine pipe having the core material therein so that the core material is easily removed from the pipe. According to the experiment, if the core material having a small diameter and a short length is covered with the forming material, it is easily removed without applying heat. However, if the core material has a thick outer diameter, it is preferably removed by applying

heat thereto. Since the forming material of the present invention is softened by heat even after it is hardened, it can remove the core material. Also, since the forming material is contracted with the lapse of time, it can remove the core material. In this case, heat deformation of the pipe can be avoided because the core material is not heated. It is preferable that the forming material is covered with a low temperature heat melting material that is varied to a fluid material at a low temperature below 100°C because high temperature affects the pipe.

If the core material is removed, the forming material 2 remaining in the pipe is generally removed by a chemical washing'process. If the core material is thinly covered with the forming material at a thickness of 2 microns to 7 microns, defects or scratches formed on the surface of the core material are strongly coupled with the forming material. In this case, the forming material and the core material are simultaneously removed in a state that they are integrally coupled with each other.

According to the results of the experiment as described above, if the forming material has a thickness of 2 microns to 7 microns, the forming material and the core material are simultaneously removed. The results of the experiment may depend on characteristics of the forming material. If the forming material 2 is thick, it is removed by a chemical washing process, after the core material is removed. After the core material and the forming material are removed, the conductive material coating layer 4 remaining in the pipe is removed by a chemical melting method.

FIG. 6 illustrates the state that the forming material and the conductive material are chemically removed from the pipe. The forming material is preferably

washed by selecting a solvent easily melted in a chemical material such as petroleum and toluene. The forming material and the conductive material coating layer can be removed by the solvent while vibration of ultrasonic waves during the washing process is generated. The ultrafine pipe of the present invention can be formed of different kinds of metal layers 5a, 5b, and 5c. The metal layers include an intensity layer and a conductive layer depending on characteristics of the respective metal layers. These layers can be obtained using different electroforming tubs during the electroforming process. For example, if an electroforming layer is formed in a nickel electroforming tub and another electroforming layer is formed in a copper electroforming tub, different kinds of metal layers of nickel and copper can be obtained.

In the present invention, the pipe may have a thin inner diameter 9 and a thick outer diameter 5. In this case, ferrule used as a connecting member of an optical cable can be manufactured. In general, metal ferrule has an outer diameter of 1250 microns and an inner diameter of 125 microns.

FIG. 7 illustrates a pipe formed of different kinds of metal layers. In the present invention, the pipe has various sections different from a section of the core material using the forming material and the die. The pipe having a desired section can be manufactured by varying the shape of the die regardless of the shape of the core material. At this time, different kinds of metal layers of Cu, Ni, and Ag can be formed by varying metal in the electroforming tub.

INDUSTRIAL APPLICABILITY The ultrafine pipe having a uniform inner diameter

and excellent processing illumination can be obtained in the present invention. Also, the size and the shape of the inner and outer diameters can exactly be controlled. The conventional ultrafine pipe manufactured by the mechanical process does not have excellent surface illumination because some defects exist. In the present invention, the surface illumination with precision of several microns can be obtained by the electroforming process. A multiple layer can be formed of a material required for the pipe by layering different kinds of metals and electroforming them.

The ultrafine pipe having inner and outer diameters of several microns or several tens of microns has limitation in mechanical process. However, in the present invention the ultrafine pipe can efficiently be manufactured regardless of such a processing limitation.

While the present invention has been described and illustrated herein with reference to the preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made therein without departing from the spirit and scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention that come within the scope of the appended claims and their equivalents.