Abstract:
Disclosed is a manufacturing method which enables manufacturing of an ultra-fine, thin contact for current inspection jigs. After a gold or gold alloy plating layer is formed, an Ni electroformed layer is formed by electroformation on the outer periphery of the formed plating layer. After a resistant layer is formed on the outer periphery of the Ni electroformed layer, a spiral groove is formed in the resistant layer by laser exposure, and etching is carried out using the resistant layer as a masking material. The Ni electroformed layer is removed from the part of the resistant layer where the spiral groove was formed, and then the resistant layer is removed and the plating layer is removed from the part of the spiral groove section where the Ni electroformed layer was removed. The core material is then removed, leaving the plating layer inside the periphery of the Ni electroformed layer.

Description:
TECHNICAL FIELD 
     The present invention relates to a current inspection jig which is used in a current inspection apparatus, and in particular, to a contact for a current inspection jig which is disposed in the current inspection jig and comes into elastic contact with a current inspection sample. 
     BACKGROUND ART 
     The current inspection has been carried out in various technical fields. Examples of the subjects for the current inspection include an electronic device substrate and a circuit wiring substrate such as a semiconductor integrated circuit and a flat panel display (FPD). These elements are minimized in size, densified in arrangement, and advanced in performance, and a contact for the current inspection jig such as a contact probe coming into elastic contact with a sample which is disposed on a current inspection jig used in the current inspection is also required to be ultrafine and miniaturized. 
     The inventors of the present application propose a Ni electroformed pipe as the contact for the current inspection jig which is partially provided with a spring structure to cope with the ultrafine, miniaturized structure (Patent Literature 1). 
     The Ni electroformed pipe partially provided with the spring structure of Patent Literature 1 is manufactured to be ultrafine and thin such that the external diameter is 32 μm to 500 μm and the internal diameter is 30 μm to 450 μm, so that a high elastic property can be exhibited. The Ni electroformed pipe is manufactured by applying a manufacturing method (Patent Literature 2) proposed by the inventors of the application. 
     In addition, regarding the ultrafine spring structure, there is proposed a manufacturing method in which, after the resist layer is formed on the outer periphery of a hollow ultrafine pipe and the resist layer is irradiated with exposure beams to make a spiral groove of a uniform slit width thereon, the etching is performed by using the resist layer as a masking material and the ultrafine pipe wall on the formed groove portion is removed (Patent Literature 3). 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Patent Application Laid-Open (JP-A) No. 2008-25833 
     Patent Literature 2: Japanese Patent Application Laid-Open (JP-A) No. 2004-115838 
     Patent Literature 3: Japanese Patent Application Laid-Open (JP-A) No. 2009-160772 
     SUMMARY OF INVENTION 
     Technical Problem 
     Since the Ni electroformed pipe partially provided with the spring structure proposed in Patent Literature 1 is manufactured ultrafine and thin, and can exhibit a high elastic property, there is a strong possibility that the current inspection is widely used in various technical fields in which samples are minimized in size, densified in arrangement, and advanced in performance. 
     Even though the samples for the current inspection are minimized in size, densified in arrangement, and advanced in performance, a contact for a current inspection jig which is made of the Ni electroformed pipe partially provided with the spring structure is also required to be manufactured with higher accuracy and precision. 
     An object of the invention is to propose a method of manufacturing a contact for a current inspection jig through which an ultrafine, thin contact for the current inspection jig provided with an electroformed spring structure can be manufactured with higher accuracy and precision; the contact for the current inspection jig manufactured through the method; and the current inspection jig which is provided with the contact. 
     Solution to Problem 
     According to an aspect of the present invention, a method of manufacturing a contact for a current inspection jig having an electroformed spring structure, the method includes: forming a gold or gold alloy plating layer on an outer periphery of a core material through plating and forming a Ni electroformed layer on an outer periphery of the formed plating layer through electroforming; forming a resist layer on an outer periphery of the Ni electroformed layer and exposing the resist layer under laser beams to form a spiral groove in the resist layer; performing etching by using the resist layer as a masking material to remove the Ni electroformed layer of a portion in which the spiral groove is formed in the resist layer; removing the resist layer and removing the plating layer of the spiral groove portion from which the Ni electroformed layer is removed; and removing the core material while the plating layer is left on an inner periphery of the Ni electroformed layer. 
     According to another aspect of the present invention, one end of a contact for the current inspection jig which is manufactured through the method as described above and is provided with an electroformed spring structure is formed as a contact end to a sample, and the other end is formed as a connection portion to the current inspection jig. 
     According to still another aspect of the present invention, a current inspection jig is provided with the contact for the current inspection jig as described above. 
     Advantageous Effects of Invention 
     According to the invention, an ultrafine, thin contact for a current inspection jig which is provided with an electroformed spring structure, can be manufactured with higher accuracy and precision. Since the contact for the current inspection jig is provided with a gold or gold alloy plating layer therein, it can exhibit an excellent conductivity. Then, it is possible to provide a current inspection jig provided with the contact for the current inspection jig which is manufactured with high accuracy and precision as described above and exhibit the excellent conductivity. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram schematically illustrating an exemplary arrangement of a continuous treatment apparatus which performs processes of forming a plating layer on the outer periphery of a core material through plating and then of forming a Ni electroformed layer on the outer periphery of the formed plating layer through the electroforming, in which  FIG. 1(   a ) is a plan view and  FIG. 1(   b ) is a side view. 
         FIG. 2  is a block diagram schematically illustrating a manufacturing method according to the invention. 
         FIG. 3  is a diagram illustrating a manufacturing procedure according to the invention, in which  FIG. 3(   a ) is a side view illustrating a state in which a spiral groove is formed in a resist layer and an enlarged cross-sectional view partially illustrating a stacked state of a core material, a gold plating layer, and a Ni electroformed layer at the portions taken along the lines X-X, Y-Y, and Z-Z;  FIG. 3(   b ) is a side view illustrating a state in which the Ni electroformed layer is removed through etching from the portion where the spiral groove is formed in the resist layer and an enlarged cross-sectional view partially illustrating the stacked state of the core material, the plating layer, and the Ni electroformed layer at the portions taken along the lines X-X, Y-Y, and Z-Z;  FIG. 3(   c ) is a side view illustrating a state where the plating layer of the spiral groove portion from which the resist layer and the Ni electroformed layer are removed is removed and an enlarged cross-sectional view partially illustrating the stacked state of the core material, the plating layer, the Ni electroformed layer at the portions taken along the lines X-X, Y-Y, and Z-Z; and  FIG. 3(   d ) is a side view illustrating a state where the core material is removed and an enlarged cross-sectional view partially illustrating the stacked state of the plating layer and the Ni electroformed layer at the portions taken along the lines X-X and Y-Y. 
         FIGS. 4(   a ) and  4 ( b ) are side views illustrating an example of a contact for a current inspection jig which is manufactured according to the manufacturing method of the invention. 
         FIG. 5  is a cross-sectional view of the contact for the current inspection jig illustrated in  FIG. 4(   a ). 
         FIGS. 6(   a ) and  6 ( b ) are side views illustrating another example of the contact for the current inspection jig which is manufactured according to the manufacturing method of the invention. 
         FIG. 7  is a cross-sectional view illustrating another example of the contact for the current inspection jig which is manufactured according to the manufacturing method of the invention. 
         FIGS. 8(   a ),  8 ( b ),  8 ( c ), and  8 ( d ) are side views partially illustrating tip end shapes on the sample contact side of the contact for the current inspection jig which is manufactured according to the manufacturing method of the invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An ultrafine, thin contact for a current inspection jig which is provided with an electroformed spring structure according to the invention can be manufactured as described below. 
     After a gold or gold alloy plating layer is formed on the outer periphery of a core material through the plating, a Ni electroformed layer is formed on the outer periphery of the formed plating layer through the electroforming. 
     Examples of the core material may include an ultrafine metal wire and an ultrafine resin wire having an external diameter of 5 μm or more. Examples of the metal wire may include a stainless steel wire, an aluminum wire, and the like. 
     Examples of the resin wire may include a synthetic resin wire which is made of a nylon resin, a polyethylene resin, and the like. 
     Further, in a case where the resin wire is employed as the core material, there is a need to perform non-electrolytic plating for forming the gold or gold alloy plating layer. In consideration of the productivity, it is preferable that the metal wire be used as the core material and the gold or gold alloy plating layer be formed through electrolytic plating. 
     The gold or gold alloy plating layer is preferably formed to have a wall thickness of 0.2 μm to 1 μm, and the Ni electroformed layer formed on the outer periphery through the electroforming is preferably formed to have a wall thickness of 5 μm to 35 μm. 
     The contact for the current inspection jig which is manufactured by a manufacturing method according to the invention and the current inspection jig having the contact, for example, are used as a contact probe for substrate inspection having the probe, which is used for manufacturing an integrated circuit such as an LSI, and a current inspection jig provided with the contact. In other words, the contact and the current inspection jig are used for the current inspection of an electronic device substrate, a circuit wiring substrate, and the like which are minimized in size, densified in arrangement, and advanced in performance, and for the current inspection of other ultrafine, high-density samples. Herein, the manufactured contact for the current inspection jig is required to be ultrafine and thin in size such as the external diameter of about 20 μm to 500 μm, and the wall thickness of about 2.5 μm to 50 μm. The above-mentioned wall thicknesses of the gold or gold alloy plating layer and the Ni electroformed layer are determined in correspondence with the above-mentioned size of the manufactured contact for the current inspection jig. In addition, as to be described later, a predetermined portion of the Ni electroformed layer is dissolved and removed through the etching, and a predetermined portion of the plating layer is dissolved and removed through the subsequent processes, so that a spiral groove having a desired shape and size is formed with accuracy and precision. Therefore, the wall thicknesses are determined from the viewpoint of forming the spiral structure having an accurate and precise size of a slit width. 
     Next, the resist layer (a wall thickness of 2 μm to 50 μm) is formed on the outer periphery of the core material which includes the gold or gold alloy plating layer and the Ni electroformed layer formed on the outer periphery thereof. 
     The resist layer, for example, is formed such that the core material which includes the gold or gold alloy plating layer and the Ni electroformed layer formed on the outer periphery thereof is immersed into a photoresist chamber containing a photoresist solution for a predetermined time period. 
     In this way, after the formation of the resist layer on the outer periphery of the Ni electroformed layer, the resist layer is exposed under laser beams to form the spiral groove in the resist layer. 
     On performing the laser exposure, the core material having the resist layer formed thereon moves toward the upper side or the lower side in the vertical direction at a predetermined speed while the core material rotates around its center axis. On the other hand, the outer periphery of the core material corresponding to a predetermined range of the spiral structure to be formed in the longitudinal direction of the core material is irradiated with the laser beams. 
     Further, in a case where a positive photoresist is used, the portion exposed under the laser beams is dissolved by a developing solution to form the spiral groove in the resist layer. On the other hand, in a case where a negative photoresist is used, the portion exposed under the laser beams is not dissolved by the developing solution. Therefore, the portion unexposed under the laser beams is dissolved by the developing solution to form the spiral groove in the resist layer. The irradiation of the laser beams will be carried out by taking the situation into consideration. 
     With the formation of the spiral groove in the resist layer, the outer periphery of the Ni electroformed layer in the spiral groove portion formed in the resist layer is exposed. 
     Next, the etching is performed by using the resist layer remaining on the outer periphery of the Ni electroformed layer as a masking material, and the Ni electroformed layer is removed from the spiral groove portion formed in the resist layer. 
     For example, as described above, the core material in which the spiral groove is formed in the resist layer formed on the outer periphery of the Ni electroformed layer is immersed into an electropolishing acid solution so as to be electropolished. In this way, the etching is performed by using the resist layer remaining on the outer periphery of the Ni electroformed layer as the masking material, and the Ni electroformed layer is removed from the spiral groove portion formed in the resist layer. 
     Next, with the removal of the resist layer, the gold or gold alloy plating layer is removed from the spiral groove portion where the Ni electroformed layer has been removed. 
     For example, the removal of the plating layer is carried out by cleaning the core material, in which the Ni electroformed layer is removed from the spiral groove, in a predetermined solution with ultrasonic waves. 
     Finally, the core material is removed while the gold or gold alloy plating layer is left on the inside of the Ni electroformed layer. 
     In order to remove the core material while the gold or gold alloy plating layer is left on the inside of the Ni electroformed layer, there may employ a method in which the core material is stretched from one side or both sides thereof to make the cross-sectional area reduced, and a gap is formed between the outer periphery of the core material and the inner peripheral of the plating layer so as to pull out the core material. In addition, the core material may be removed by being immersed into a solution to chemically or electrochemically dissolve the core material. 
     In a case where the stainless steel wire or the resin wire is used as the core material, the core material is removed by the former pulling method. In a case where the aluminum wire is used as the core material, the latter chemical, electrochemical removal method may be employed. In this case, a strong alkaline solution such as sodium hydroxide and potassium hydroxide having little impact over an electrodeposit may be used as the solution. 
     According to the manufacturing method of the invention, although it may be affected by which one of the negative type and the positive type of resist material will be employed, basically, a width of the slit in the spiral structure portion can be set by the laser exposure. In addition to that the region for forming the spiral structure portion can be arbitrarily set in the ultrafine, thin Ni electroformed tube, the width of the slit in the spiral structure portion can be arbitrarily set, thereby providing the contact for the current inspection jig having an elastic property with high accuracy. 
     According to the manufacturing method of the invention, as described above, the etching is performed by using the resist layer remaining on the outer periphery of the Ni electroformed layer as the masking material, thereby removing the Ni electroformed layer from the spiral groove portion formed in the resist layer. 
     In this case, since the gold or gold alloy plating layer is present inside the Ni electroformed layer, an etching solution can be prevented from flowing into the Ni electroformed layer portion other than the formed spiral groove portion. Therefore, only the spiral groove portion formed in the Ni electroformed layer is immersed into the etching solution and is dissolved. As a result, a slit width in the spiral structure portion of the Ni electroformed tube which has been formed at the removal of the core material can be used just as the precise slit width formed through the laser exposure, and the slit width of the spiral structure portion can be set to be a uniform slit width as desired. 
     If the width of the slit in the spiral structure portion is set to be the uniform slit width as desired, the elastic property when one end of the manufactured contact for the current inspection jig is connected to the current inspection jig and the other end is pushed to be placed on the sample will be improved. 
     In addition, according to the manufacturing method of the invention, since the gold or gold alloy plating layer is present inside the Ni electroformed layer when the etching is performed, the etching solution is prevented from reaching the core material. If the etching solution is in contact with the core material, the core material is corroded, and in a case where a pulling method is employed to remove the core material, the core material may be broken in the middle of the pulling, so that it is difficult to remove the core material completely. 
     In the invention as described above, at the beginning, the gold or gold alloy plating layer is formed on the outer periphery of the core material through the plating, and then the Ni electroformed layer is formed on the outer periphery of the formed plating layer through the electroforming. 
     In this way, the significance in the formation of the gold or gold alloy plating layer inside the Ni electroformed layer will be exhibited in the subsequent process of “performing the etching by using the resist layer as the masking material, and removing the Ni electroformed layer from the portion of the spiral groove formed in the resist layer”. 
     In other words, as described above, since the gold or gold alloy plating layer is present inside the Ni electroformed layer, it can be prevented that the etching solution flows back into the Ni electroformed layer portion other than the formed spiral groove portion. Then, the slit width of the spiral structure portion can be set to be the uniform slit width as desired. 
     In the invention, on etching, the Ni electroformed layer portion (the Ni electroformed layer portion other than the portion of the spiral groove formed in the resist layer) which will remain as the spring structure portion is masked with the resist layer on the outside thereof and with the gold or gold alloy plating layer on the inside thereof, respectively. In the case, the spring structure portion can be formed to have a thickness which has been designed as its dimension through the etching. 
     Particularly, since the Ni electroformed layer is configured to be formed on the outer periphery of the gold or gold alloy plating layer formed on the inside through the electroforming, there is no concern about that the etching solution is permeated to the contact face between the plating layer and the Ni electroformed layer (the etching solution flow back thereto) and thus the end portion facing the slit inside the Ni electroformed layer and the very inside are corroded by the etching solution. 
     Therefore, the slit width of the spiral structure portion can be set to be the uniform slit width as desired, and the wall thickness of the spiral structure portion can be precisely formed to have a dimension as it has been designed. 
     Forming the slit width of the spiral structure portion to be the uniform slit width as desired and forming the wall thickness to be the desired thickness (constant thickness) are significantly important in making the spring unit exhibit the desired elastic property, and in making the stable durability exhibited even when contraction motions are repeatedly performed plural times (hundreds of thousands of times to millions of times) like a probe. 
     According to the invention, in order to prevent, in advance, the etching solution from being permeated to the inside of the Ni electroformed layer (the etching solution flows back thereto) to corrode the end portion facing the slit inside the Ni electroformed layer and the very inside in the process of performing the etching with the use of the resist layer as the masking material to remove the Ni electroformed layer from the portion of the spiral groove formed in the resist layer, a layer member serving as the resist and masking material in an etching treatment process is formed on the outer periphery of the core material before the formation of the Ni electroformed layer on the outer periphery of the core material. 
     In this way, since the layer formed on the outer periphery of the core material before the formation of the Ni electroformed layer on the outer periphery of the core material has no choice but to be left on the inside of the Ni electroformed layer even after the formation of the spiral structure portion, the gold or gold alloy is employed to form the gold or gold alloy plating layer in consideration of the conductivity. 
     Example 1 
     An example of a method of manufacturing an ultrafine, thin contact  20  for a current inspection jig which is provided with an electroformed spring structure using an SUS wire having a diameter (5 μm to 450 μm) as a core material will be described. 
       FIG. 1  is a diagram schematically illustrating an exemplary arrangement of a continuous treatment apparatus which performs processes of forming a gold plating layer  12  on the outer periphery of the core material through plating and then of forming a Ni electroformed layer  13  on the outer periphery of the formed gold plating layer  12  through the electroforming, and  FIG. 2  is a block diagram schematically illustrating an example of a manufacturing method according to the invention. 
     A supply unit  1  is provided with a reel  10  around which the SUS wire  11  serving as the core material is wound. 
     The SUS wire  11  is reeled out from the reel  10  of the supply unit  1  by a transport roller  14  of a containing unit  5 , and transferred to a gold plating unit  4  through a cleaning unit  2  and a current-supply and transport unit  3 . 
     The cleaning unit  2  is charged with a predetermined weak alkaline solution or a weak acidic solution, in which the outer periphery of the SUS wire  11  is cleaned. 
     The gold plating unit  4  is filled with a predetermined electrolytic solution, for example, a non-cyanide Au solution, and through the plating, a predetermined wall thickness (0.2 μm to 1 μm) of the gold plating layer  12  is formed on the outer periphery of the SUS wire  11  which has been transferred into the gold plating unit  4 . 
     Then, the SUS wire  11  of which the outer periphery is formed with the gold plating layer  12  by a transport roller  15  of the containing unit  9  provided with a cutting unit (not illustrated) is transferred to a nickel electroforming unit  8  through the cleaning unit  6  and a current-supply and transport unit  7 . 
     The cleaning unit  6  contains the predetermined weak alkaline solution or the weak acidic solution, in which the outer periphery of the gold plating layer  12  is cleaned. 
     The nickel electroforming unit  8  contains the predetermined electrolytic solution, for example, a nickel sulfonic acid solution, and through the electroforming, a predetermined wall thickness (3 μm to 50 μm) of the Ni electroformed layer  13  is formed on the outer periphery of the gold plating layer  12  of the SUS wire  11  which has been transferred into the nickel electroforming unit  8 . 
     The transport speeds of the transport rollers  14  and  15  of the containing units  5  and  9  are adjusted depending on how much wall thicknesses of the gold plating layer  12  and the Ni electroformed layer  13  will be formed on the outer periphery of the SUS wire  11 . 
     Then, the SUS wire  11  in which the gold plating layer  12  and the Ni electroformed layer  13  are stacked on the outer periphery is cut by a desired length, for example, 30 mm by the cutting unit (not illustrated) which is provided in the containing unit  9 . 
     Next, the SUS wire  11  in which the gold plating layer  12  and the Ni electroformed layer  13  are formed on the outer periphery is immersed into the photoresist chamber containing a positive photoresist solution for the predetermined time period, and a predetermined wall thickness (2 μm to 30 μm) of a resist layer  30  is formed on the outer periphery of the Ni electroformed layer  13 . 
     Next, the SUS wire  11  moves toward the upper side in the vertical direction (an arrow  42 ) or toward the lower side in the vertical direction (an arrow  43 ) at a predetermined speed while the core material rotates in a direction of an arrow  40  or  41  around the center axis of the SUS wire  11  in which the resist layer  30  is formed. At the same time, the outer periphery of a spiral structure portion  14  ( FIG. 3(   d )) corresponding to a predetermined range of the spiral structure to be formed in the longitudinal direction of the SUS wire  11  is irradiated with the laser beams. 
     Thereafter, the resist layer  30  of the portion exposed with the laser beams is immersed into the developing solution to be dissolved, so that a spiral groove  31  is formed in the resist layer  30  ( FIG. 3(   a )). With the formation of the spiral groove  31  in the resist layer  30 , the outer periphery of the Ni electroformed layer  13  is exposed from the portion where the spiral groove  31  is formed ( FIG. 3(   a )). 
     Next, the SUS wire  11  in which the spiral groove  31  is formed in the resist layer  30  which has been formed on the outer periphery of the Ni electroformed layer  13  is immersed into the electropolishing acid solution to be electropolished. Therefore, the etching is performed by using the resist layer  30  remaining on the outer periphery of the Ni electroformed layer  13  as the masking material, so that the Ni electroformed layer  13  is removed from the portion of the spiral groove  31  formed in the resist layer  30  ( FIG. 3(   b )). In this way, the outer periphery of the gold plating layer  12  is exposed from the portion where the spiral groove  31  is formed ( FIG. 3(   b )). 
     Next, with the removal of the resist layer  30 , the SUS wire  11  is subjected to ultrasonic cleaning in pure water at a temperature (about 50 degrees) higher than a room temperature, so that the gold plating layer  12  is removed from the portion in which the Ni electroformed layer  13  corresponds to the removed spiral groove  31  ( FIG. 3(   c )). In this way, the outer periphery of the SUS wire  11  is exposed from the portion where the spiral groove  31  is formed ( FIG. 3(   c )). 
     Finally, the SUS wire  11  is stretched from its one or both ends to make the cross-sectional area thereof small; a gap is formed between the outer periphery of the SUS wire  11  and the inner peripheral of the gold plating layer  12 ; and the SUS wire  11  is pulled out. Therefore, the SUS wire  11  is removed while the gold plating layer  12  is left on the inside of the Ni electroformed layer  13 , thereby forming the ultrafine, thin contact  20  for the current inspection jig which is provided with the Ni electroformed spring structure ( FIG. 3(   d ),  FIG. 4(   a ), and  FIG. 5) . 
     The contact  20  for the current inspection jig manufactured as described above is a thin Ni electroformed tube which is provided with the gold plating layer  12  on the inside thereof and partially includes the spiral structure portion  14  as illustrated in  FIG. 3(   d ),  FIG. 4(   a ), and  FIG. 5 . The thin Ni electroformed tube which is provided with the gold plating layer  12  on the inside thereof is formed such that the SUS wire  11  is removed from the gold plating layer  12  and the Ni electroformed layer  13 , which have been formed on the outer periphery of the SUS wire  11  serving as the core material, while the gold plating layer  12  is left on the inside of the Ni electroformed layer  13 . 
     Then, the portion corresponding to the spiral groove  31  in the Ni electroformed layer  13  is dissolved through the etching to form a spiral slit  31   a  in the Ni electroformed layer  13 , thereby forming the spiral structure portion  14 . 
       FIG. 4(   a ) is a side view illustrating an example of the ultrafine, thin contact  20  for the current inspection jig which is manufactured according to the manufacturing method of the invention and provided with the electroformed spring structure, in which the spring structure portion denoted by the reference numeral  14  is formed partially. 
     In addition, as illustrated in  FIG. 6 , the contact may be manufactured just like contacts  21  and  22  for the current inspection jig which includes tubular shaped portions  23  made of the Ni electroformed layer provided with the gold plating layer on the inside thereof and a plurality of spring structure portions  24   a ,  24   b ,  25   a ,  25   b , and  25   c.    
     The contact  20  for the current inspection jig according to the invention has been manufactured using the SUS wire  11  of the 21 μm external diameter through the above-described processes, in which the entire length L 1  is 1 mm, the lengths L 2  and L 4  of the tubular shaped portions made of the Ni electroformed layer  13  which is provided with the gold plating layer  12  on the inside thereof are 0.1 mm, the length L 3  of the spring structure portion  14  is 0.8 mm, the external diameter φ 1  is 35 μm, and the internal diameter φ 2  is 21 μm. 
     Further, the above numerical values L 1 , L 2 , L 3 , L 4 , φ 1 , and φ 2  may be set to numeral values in accordance with design conditions. 
     In a case where a short length L 1  of the contact  20  is manufactured, after a tube body made of the Ni electroformed layer  13  in which the gold plating layer  12  is formed on the inside thereof is cut at every 1 mm, the SUS wire  11  is removed, so that a plurality of the contacts  20  can be manufactured at the same times. 
     In other words, as described above, in a case where the SUS wire  11  having the entire length of 30 mm is used as the core material, the spring structure portion  14  is formed through the laser exposure such that the portion in the range of 0.1 mm from the one end is formed in a tubular shape, the portion in the subsequent range of 0.8 mm is formed to be the spring structure portion, the portion in the subsequent range of 0.2 mm is formed in the tubular shape, and the portion in the subsequent range of 0.8 mm is formed to be the spring structure portion. After being subjected to the process illustrated in  FIG. 3(   c ) and before being removed, the SUS wire  11  is cut at every 1 mm using the laser beam. Thereafter, when the SUS wire  11  is removed, 30 pieces of the contacts  20  can be manufactured at the same time. As described above, in a case where the SUS wire  11  is stretched from one or both ends to be removed, there is a need to take holding portions into consideration which are necessary to be formed at the end portions. Even in this case, 25 to 26 pieces of the contacts  20  each having the entire length of 1 mm can be manufactured at the same time. 
     In addition, an ultrafine, thin contact  20   a  for the current inspection jig which is provided with the Ni electroformed spring structure illustrated in  FIG. 4(   b ) may be manufactured. In this case, the SUS wire  11  having the entire length of 30 mm is subjected to the laser exposure to form the spring structure portion  14  over the entire length; before the removal, the SUS wire  11  is cut to have a desired length using the laser beam; and then the SUS wire  11  is removed. Therefore, a plurality of the contacts  20   a  can be manufactured at the same time. 
     The contact for the current inspection jig may be provided with the spring structure formed over parts or the entire length just like those illustrated in  FIG. 3(   d ),  FIG. 4(   a ), and  FIG. 5 , or that illustrated in  FIG. 4(   b ). 
     In either case, according to the manufacturing method of the invention, the etching is performed by using the resist layer  30  as a mask in which the spiral groove  31  is formed through the laser exposure to dissolve and remove the predetermined portion of the Ni electroformed layer  13 , and then to remove the portion of the gold plating layer  12  corresponding to the spiral groove  31  from which the Ni electroformed layer  13  is removed, so that the spring structure portion  14  is formed. Therefore, the spiral groove  31  having a desired shape and size is accurately and precisely formed, and thus the spiral structure which includes the spiral slit  31   a  having the accurate, precise size of the slit width can be formed. 
     The ultrafine, thin contacts  20  and  20   a  ( FIG. 4 ) for the current inspection jig which is provided with the electroformed spring structure manufactured according to the manufacturing scheme of the invention can exhibit the excellent elastic property. This property is one of the properties, as described above, which can be exhibited from the structure in which the width of the slit  31   a  in the spiral structure portion is set to be the uniform slit width as desired. 
     The contact for the current inspection jig according to the above-described invention has been manufactured such that the wall thickness of the Ni electroformed layer  13  provided with the gold plating layer therein is 10 μm; the external diameter φ 1  is 80 μm; the length L 3  of the spring structure portion  14  is 2 mm; and the number of windings is 25, in which a spring load has been 2 gf/0.2 mm. In addition, the contact for the current inspection jig according to the above-described invention has been manufactured such that the wall thickness of the Ni electroformed layer  13  provided with the gold plating layer therein is 10 μm; the external diameter φ 1  is 50 μm; the length L 3  of the spring structure portion  14  is 2 mm; and the number of windings is 40, in which the spring load has been 4 gf/0.2 mm. 
     The ultrafine, thin contacts  20  and  20   a  ( FIG. 4 ) for the current inspection jig provided with the electroformed spring structure which has been manufactured according to the manufacturing scheme of the invention use their one ends as contact ends to the sample and the other ends as connection portions to the current inspection jig. 
     In this case, in  FIG. 4(   a ), the one end denoted by the reference numeral  17  can be used as the contact end to the sample, the other end denoted by the reference numeral  16  can be used as the connection portion to the current inspection jig. 
     In addition, as illustrated in  FIG. 7 , a conductive pin  26  is inserted to the inside, and a tip end  27  of the pin  26  abutted on a tip end  17  of the contact  20  for the current inspection jig is used as the contact end to the sample, so that the one end of the contact  20  for the current inspection jig can be used as the contact end to the sample. 
     In a case of the form illustrated in  FIG. 7 , the pin  26  may be fixed to the portion denoted by the reference numeral  18  in the drawing through a medium such as a swage, welding, and an adhesive. 
     In addition, in a case of the form illustrated in  FIG. 7 , the conductive pin  26  inserted to the inside may be manufactured by an ultrafine wire made of a metal wire excellent in conductivity, for example, platinum, rhodium, or an alloy thereof, or an ultrafine tungsten or BeCu (beryllium copper) wire which is subjected to the Ni plating and then the Au plating. 
     In a case where the one end denoted by the reference numeral  17  of the contact  20  for the current inspection jig is used as the contact end to the sample, or in a case where the tip end  27  of the pin  26  abutting on the one end of the contact  20  for the current inspection jig is used as the contact end to the sample, the shape of the contact end may be various shapes such as a taper shape ( FIG. 8(   a )), a bent shape ( FIG. 8(   b )) with a radius R, a smooth flat shape ( FIG. 8(   c )), and a crown shape ( FIG. 8(   d )). 
     The contacts  20  and  20   a  ( FIG. 4  and  FIG. 7 ) for the current inspection jig may be used as a contact probe for inspecting substrates when the integrated circuit such as an LSI is manufactured. In addition, the current inspection jigs provided with the contacts  20  and  20   a  ( FIG. 4  and  FIG. 7 ) for the current inspection jig are used for the current inspection of other ultrafine, high-density samples as well as the current inspection of the electronic device substrate, the circuit wiring substrate, and the like. 
     Hitherto, the exemplary embodiments of the invention has been described with reference to the accompanying drawings, the invention is not limited to these embodiments, but various modifications can be made without departing from the technical scope which can be understood from the claims. For example, in the example, the gold plating layer  12  serving as the core material has been formed on the outer periphery of the SUS wire  11  through the plating, but the plating layer made of the gold alloy may be formed instead of the gold plating layer. 
     REFERENCE SIGNS LIST 
     
         
           11  SUS wire (core material) 
           12  gold plating layer 
           13  Ni electroformed layer 
           14  spiral structure portion 
           30  resist layer 
           31  spiral groove 
           31   a  spiral slit 
           20 ,  20   a ,  21 ,  22  contact for current inspection jig