Electroplating method using combination of vibrational flow in plating bath and plating current of pulse

Abstract

In an electroplating method, a plating target article (X) disposed so as to be in contact with plating bath ( 14 ) is set as a cathode while a metal member disposed so as to be in contact with the plating bath ( 14 ) is set as an anode, and a voltage is applied between the cathode and the anode while vibrational flow is induced by vibrating vibrational vanes ( 16 f ) which are fixed in multi-stage style to a vibrating rod ( 16 e ) vibrating in the plating bath ( 14 ) interlockingly with vibration generating means ( 16 d ). Plating current flowing from the anode through the plating bath ( 14 ) to the cathode is pulsed and alternately set to one of a first state where the plating current keeps a first value I 1 for a first time T 1 and a second state where the plating current keeps a second value I 2 having the same polarity as the first value I 1 for a second time T 2 , the first value I 1 being five or more times larger than the second value I 2 , and the first time T 1 being three or more times longer than the second time T 2.

What is claimed is:  
     
         1 . An electroplating method, characterized in that a plating target article disposed so as to be in contact with plating bath is set as a cathode while a metal member disposed so as to be in contact with the plating bath is set as an anode, and a voltage is applied between the cathode and the anode while vibrational flow is induced by vibrating vibrational vanes which are fixed in one-stage or multi-stage style to a vibrating rod vibrating in the plating bath interlockingly with vibration generating means, wherein plating current flowing from the anode through the plating bath to the cathode is pulsed and alternately set to one of a first state where the plating current keeps a first value I 1  for a first time T 1  and a second state where the plating current keeps a second value I 2  having the same polarity as the first value I 1  for a second time T 2 , the first value I 1  being five or more times larger than the second value I 2 , and the first time T 1  being three or more times longer than the second time T 2 .  
     
     
         2 . The electroplating method as claimed in    claim 1   , wherein the first value I 1  is 6 to 25 times as large as the second value I 2 , and the first time T 1  is 4 to 25 times as long as the second time T 2 .  
     
     
         3 . The electroplating method as claimed in    claim 1   , wherein the first value I 1  is set to 0.01 to 300 seconds.  
     
     
         4 . The electroplating method as claimed in    claim 1   , wherein the vibrational vanes are vibrated at an amplitude of 0.05 to 10.0 mm and a vibration frequency of 200 to 1500 revolutions per minute.  
     
     
         5 . The electroplating method as claimed in    claim 1   , wherein the vibrational vanes are vibrated so that the vibrational flow of the plating bath has a three-dimensional flow rate of 150 mm/second or more.  
     
     
         6 . The electroplating method as claimed in    claim 1   , wherein the vibration generating means vibrates at 10 to 500 Hz.  
     
     
         7 . The electroplating method as claimed in    claim 1   , wherein the plating target article is vibrated at an amplitude of 0.05 to 5.0 mm and a vibration frequency of 100 to 300 revolutions per minute.  
     
     
         8 . The electroplating method as claimed in    claim 1   , wherein the plating target article is swung at a swinging width of 10 to 100 mm and a swinging frequency of 10 to 30 times per minute.  
     
     
         9 . The electroplating method as claimed in    claim 1   , wherein the plating target article has a face to be plated having a microstructure of a dimension of 50 μm or less.  
     
     
         10 . The electroplating method as claimed in    claim 1   , wherein a plurality of plating target articles are accommodated in a holding container, said holding container having small holes through which liquid of the plating bath is allowed to pass and being equipped with an electrically conductive member which is brought into contact with the plating target articles to make current flow through the plating target articles, and wherein said holding container is rotated around the rotational center corresponding to a non-vertical direction in the plating bath to roll the plating target articles in said holding container to thereby repeat the contact and separation between each of the plating target articles and said electrically conductive member.  
     
     
         11 . The electroplating method as claimed in    claim 10   , wherein the width of each of the plating target articles is equal to 5 mm or less.