Contact probe and fabrication method thereof

Abstract

A contact probe is fabricated by a method including a lithography step and a plating step. The contact probe includes a plunger unit to form contact with a circuit to be tested, a spring unit, and a lead wire connection unit, all formed integrally so as to have a three dimensional configuration with uniform thickness with respect to a predetermined plane configuration in a thickness direction perpendicular to the predetermined plane configuration. Preferably, a guide unit parallel to the spring unit is also formed integrally. Further preferably, the contact probe is formed integrally also including a stopper for each unitary configuration of the spring unit constituted by a leaf spring.

What is claimed is:  
     
         1 . A contact probe comprising: 
 a plunger unit to form contact with a circuit to be tested,    a spring unit supporting said plunger unit at one end, and    a lead wire connection unit electrically connecting another end of said spring unit with a lead wire,    wherein said plunger unit, said spring unit and said lead wire connection unit are formed integrally.    
     
     
         2 . The contact probe according to  claim 1 , wherein said plunger unit, said spring unit and said lead wire connection unit are formed integrally so as to have a three dimensional configuration with uniform thickness with respect to a predetermined plane configuration in a thickness direction perpendicular to said predetermined plane configuration.  
     
     
         3 . The contact probe according to  claim 1 , comprising a guide unit arranged parallel to said spring unit to maintain said spring unit at a constant posture, wherein said plunger unit, said spring unit, said lead wire connection unit and said guide unit are formed integrally.  
     
     
         4 . The contact probe according to  claim 3 , wherein said plunger unit, said spring unit, said lead wire connection unit and said guide unit are formed integrally so as to have a three dimensional configuration with uniform thickness with respect to a predetermined plane configuration in a thickness direction perpendicular to said predetermined plane configuration.  
     
     
         5 . The contact probe according to  claim 1 , comprising a cylindrical member including a conductor having an inner wall covered with an insulator, said cylindrical member surrounding an outer side of said spring unit, and said plunger unit protruding from said cylindrical member.  
     
     
         6 . The contact probe according to  claim 5 , wherein said lead wire connection unit and said cylindrical member are fixed to each other.  
     
     
         7 . The contact probe according to  claim 1 , wherein said spring unit includes a configuration in which a unitary configuration of a leaf spring is repeated several times and connected.  
     
     
         8 . The contact probe according to  claim 7 , wherein said spring unit includes a stopper for each said unitary configuration, said stopper arranged so as to abut against the leaf spring forming said unitary configuration to prevent further elastic deformation when the elastic deformation of said spring unit in a longitudinal direction exceeds a predetermined value.  
     
     
         9 . The contact probe according to  claim 1 , wherein said plunger unit includes a top portion and inclination portions sandwiching said top portion, wherein said inclination portions are angled at not more than 90° with respect to each other, and a radius of curvature of a transverse section of said top portion is not more than 5 μm.  
     
     
         10 . The contact probe according to  claim 1 , wherein a portion or entire surface of said plunger unit including said top portion is covered with a material of a volume resistivity lower than the volume resistivity of the material inside said plunger unit.  
     
     
         11 . A method of fabricating a contact probe, said contact probe including 
 a plunger unit to form contact with a circuit to be tested,    a spring unit supporting said plunger unit at one end, and    a lead wire connection unit electrically connecting another end of said spring unit with a lead wire,    wherein said plunger unit, said spring unit and said lead wire connection unit are formed integrally so as to have a three dimensional configuration with uniform thickness with respect to a predetermined plane configuration in a thickness direction perpendicular to said predetermined plane configuration,    said method of fabricating a contact probe comprising: 
 a resist formation step of coating a resist on a substrate having conductivity,  
 an exposure step of exposing said resist using an integral mask,  
 a first resist removal step of removing a portion of said resist that is exposed by said exposure step,  
 a forming step of filling with metal a portion of said resist removed at said first resist removal step,  
 a second resist removal step of removing a remaining portion of said resist, and  
 a substrate removal step of removing said substrate,  
 wherein said integral mask employs a mask of a configuration in which said contact probe is projected in said thickness direction.  
   
     
     
         12 . The method of fabricating a contact probe according to  claim 11 , wherein said contact probe further includes a guide unit arranged parallel to said spring unit to maintain said spring unit at a constant posture.