Abstract:
A method and apparatus for making a fixed abrasive grain wire includes, at first, inserting a wire through a sleeve that includes at least one aperture defined therein. Then, both of the wire and the sleeve are located in electroplating or electro-less plating liquid that includes abrasive grains blended therein. Finally, electroplating or electro-less plating is executed to fix some of the abrasive grains to the wire.

Description:
BACKGROUND OF INVENTION 
     1. Field of Invention 
     The present invention relates to a fixed abrasive wire and, more particularly, to a method and apparatus for making a fixed abrasive wire. 
     2. Related Prior Art 
     The photoelectrical industry has been booming recently. There is a growing need for precious, hard and brittle materials such as silicon wafers, sapphire and agate. Silicon wafers are essential for the development of integrated circuits. The silicon wafers are sliced into dies for integrated circuits. During the slicing of the silicon wafers, there is always loss of materials, and the slicing of the wafers is hence expensive. There is a need for an excellent wafer-slicing process. 
     A wafer can be sliced with a sawing wire. The sawing wire may be operated in a free abrasive manner or a fixed abrasive manner. In the free abrasive manner, a wire is used with abrasive paste for slicing. The efficiency and precision of the free abrasive operation are low, and the consumption of the abrasive paste pollutes the environment. 
     In the fixed abrasive manner, abrasive grains are fixed to a wire by adhesive, electroplating or electro-less plating for example. The efficiency and precision of the fixed abrasive operation are high, and there is no waste related to the disposal of any abrasive paste. Therefore, the fixed abrasive operation is popular. 
     A method for making a fixed abrasive wire by electroplating was devised by Ken-Ichi Ishikawa in 1994. In the method, a tank that contains abrasive grains such as diamond grains is used as a composite electroplating tank. A wall of the tank is made with apertures of a diameter of 10 mm and coated with a Teflon film that is 3 μm thick. The abrasive grains are restrained in the tank by the Teflon film while nickel-based electroplating liquid is allowed to flow through the tank. A wire electrically connected to the cathode of a power supply is buried in the abrasive grains and electroplated in the electroplating liquid so that some of the abrasive grains can be fixed to the wire. However, the area of the contact of the electroplating liquid with the wire is small, and the electroplating takes a long time. Furthermore, it is difficult to control the amount and distribution of the abrasive grains fixed to the wire. 
     In a typical method for making a fixed abrasive wire by adhesive, abrasive grains are fixed to a wire by adhesive that includes copper, tin or titanium in a high-temperature chamber filled with inert gas or a high-temperature vacuum chamber. The control over the abrasive grains is good. However, the wire and abrasive grains could be damaged in the high-temperature chamber, and mechanical properties of the resultant fixed abrasive wire are jeopardized. 
     The foregoing methods for making fixed abrasive wires are not without problems. Therefore, the present invention is intended to obviate or at least alleviate the problems encountered in prior art. 
     SUMMARY OF INVENTION 
     It is an objective of the present invention to provide a method for making a fixed abrasive wire via electroplating. 
     To achieve the foregoing objective, the method includes the step of inserting a wire through a sleeve including at least one aperture defined therein, the step of locating the wire and the sleeve in electroplating liquid including abrasive grains blended therein, and the step of executing electroplating to fix some of the abrasive grains to the wire. 
     The sleeve includes at least one open end in a shape selected from the group consisting of circular, oval, triangular or rectangular. The diameter of the open end of the sleeve is 1 to 20 mm. 
     The aperture is circular, oval, triangular or rectangular. The diameter of the aperture is 0.05 to 10 mm. 
     The abrasive grains are made of silicon carbide, baron carbide, tungsten carbide, baron nitride, diamond, aluminum oxide, zirconium oxide or quartz. The diameter of the abrasive grains is 1 to 60 μm. 
     The sleeve is located in a vertical, horizontal or inclined manner. 
     It is another objective of the present invention to provide a method for making a fixed abrasive wire via electro-less plating. 
     To achieve the foregoing objective, the method includes the step of inserting a wire through a sleeve including at least one aperture defined therein, the step of locating the wire and the sleeve in electroplating liquid including abrasive grains blended therein, and the step of executing electro-less plating to fix some of the abrasive grains to the wire. 
     The sleeve includes at least one open end in a shape selected from the group consisting of circular, oval, triangular or rectangular. The diameter of the open end of the sleeve is 1 to 20 mm. 
     The aperture is circular, oval, triangular or rectangular. The diameter of the aperture is 0.05 to 10 mm. 
     The abrasive grains are made of silicon carbide, baron carbide, tungsten carbide, baron nitride, diamond, aluminum oxide, zirconium oxide or quartz. The diameter of the abrasive grains is 1 to 60 μm. 
     The sleeve is located in a vertical, horizontal or inclined manner. 
     It is another objective of the present invention to provide an apparatus for making a fixed abrasive wire. 
     To achieve the foregoing objective, the apparatus includes a tank, reaction liquid filled in the tank, abrasive grains mixed in the reaction liquid, a sleeve including at least one aperture defined therein. The sleeve is submerged in the reaction liquid in the tank. A wire is moved through the sleeve while some of the abrasive grains are fixed to the wire. 
     The reaction liquid may be electro-less plating liquid. 
     Alternatively, the reaction liquid may be electroplating liquid. In this case, the apparatus further includes a power supply located outside the tank and at least one anode plate submerged in the reaction liquid filled in the tank and electrically connected to the anode of the power supply. 
     Other objectives, advantages and features of the present invention will be apparent from the following description referring to the fixed drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The present invention will be described via detailed illustration of several embodiments referring to the drawings wherein: 
         FIG. 1  is a front view of an apparatus for making a fixed abrasive wire according to the first embodiment of the present invention; 
         FIG. 2  is perspective view of a sleeve of the apparatus shown in  FIG. 1 ; 
         FIG. 3  is a flow chart of a method for making a fixed abrasive wire according to the second embodiment of the present invention; 
         FIG. 4  is a front view of an apparatus for making a fixed abrasive wire according to the third embodiment of the present invention; 
         FIG. 5  is a SEM photograph of a fixed abrasive wire made according to the present invention; 
         FIG. 6  is a SEM photograph of another fixed abrasive wire made according to the present invention; and 
         FIG. 7  is a SEM photograph of another fixed abrasive wire made according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Referring to  FIG. 1 , there is shown an apparatus for making a fixed abrasive wire according to a first embodiment of the present invention. The apparatus includes two sleeves  110 , three wheels or pulleys  120  and a tank  150 . The tank  150  is filled with reaction liquid  170 . Abrasive grains  180  are mixed in the reaction liquid  170 . 
     Referring to  FIG. 2 , each of the sleeves  110  includes a tubular wall  210  formed with two open ends  220  and apertures  160  transversely defined in the tubular wall  210 . The open ends  220  may be circular, oval, triangular, rectangular or in any other proper shape. The diameter of the open ends  220  is 1 to 20 mm if the open ends  220  are circular. The largest diameter of the open ends  220  is 1 to 20 mm if the open ends  220  are in another shape. 
     The apertures  160  may be circular, oval, triangular, rectangular or in any other proper shape. The diameter of the apertures  160  is 0.05 to 10 mm if the open ends  220  are circular. The largest diameter of the apertures  160  is 0.05 to 10 mm if the open ends  220  are in another shape. The apertures  160  are distributed regularly or irregularly. 
     Referring to  FIG. 1 , the sleeves  110  are submerged in the reaction liquid  170  filled in the tank  150 . The sleeves  110  extend vertically in the tank  150  as shown; however, the sleeves  110  can extend horizontally or in an inclined manner in the tank  150 . 
     Two of the wheels  120  (the “upper wheels  120 ”) are located outside the tank  150  while the other wheel  120  (the “lower wheel  120 ”) is located in the tank  150 . Each of the sleeves  110  is located between a related one of the upper wheels  120  and the lower wheel  120 . 
     There are two sleeves  110  and three wheels  120  as shown; however, there can be only one sleeve  110  or any other proper number of sleeves  110  and a corresponding number of wheels  120 . 
     The reaction liquid  170  may be electro-less plating liquid or electroplating liquid. The apparatus includes only the sleeves  110 , the wheels  120  and the tank  150  if the reaction liquid  170  is electro-less plating liquid. 
     The apparatus includes at least one anode plate  140  and a power supply  190  in addition to the sleeves  110 , the wheels  120  and the tank  150  if the reaction liquid  170  is electroplating liquid. The anode plate  140  is submerged in the reaction liquid  170  filled in the tank  150  and electrically connected to the anode of the power supply  190 . 
     The diameter of the abrasive grains  180  is 1 to 60 μm. The abrasive grains  180  may be made of silicon carbide, baron carbide, tungsten carbide, baron nitride, diamond, aluminum oxide, zirconium oxide or quartz. 
     Referring to  FIG. 3 , there is shown a method for making a fixed abrasive wire in an electroplating manner. At S 301 , a wire  130  is wound around the wheels  120  so that a section thereof is inserted through one of the sleeves  110  while another section thereof is inserted through the other sleeve  110 . The wire  130  is moved through the sleeves  110  as it is driven by the wheels  120 . The wire  130  is electrically connected to the cathode of the power supply  190 . 
     At S 302 , the wire  130  and the sleeves  110  are submerged in the electroplating liquid  170  filled in the tank  150 . 
     At S 303 , the power supply  190  is turned on to execute electroplating. Thus, the abrasive grains  180  move toward the wire  130  via the apertures  160 , and some of the abrasive grains  180  are fixed to the wire  130 . The wire  130  and the abrasive grains  180  fixed to the wire  130  become a fixed abrasive wire for slicing. 
     Referring to  FIG. 4 , there is shown a method for making a fixed abrasive wire in an electroplating manner. At S 401 , a wire  130  is wound around the wheels  120  so that a section thereof is inserted through one of the sleeves  110  while another section thereof is inserted through the other sleeve  110 . The wire  130  is moved through the sleeves  110  as it is driven by the wheels  120 . The wire  130  is electrically connected to the cathode of the power supply  190 . 
     At S 402 , the wire  130  and the sleeves  110  are submerged in the electro-less plating liquid  170  filled in the tank  150 . 
     At S 403 , the abrasive grains  180  move toward the wire  130  through the apertures  160  so that some of the abrasive grains  180  are fixed to the wire  130 . The wire  130  and the abrasive grains  180  fixed to the wire  130  become a fixed abrasive wire for slicing. 
     In another embodiment, the reaction liquid  170  is electroplating liquid including 500 grams of Ni(NH 2 SO 3 ) 2 .4H 2 O, 10 grams of NiCl.6H 2 O and 40 grams of H 3 BO 3 . The operative temperature is 40° C. to 50° C. The pH value is 3.8 to 40. The current density is 4 A/dm 2 . The average diameter of the abrasive grains  180  is 21 μm. The stirring rate is 350 to 370 rpm. The sleeves  110  are directed vertically in the tank  150 . The apertures  160  are distributed on the tubular wall  210  of each of the sleeves  110  in a symmetric manner, and the distance between any two adjacent ones of the apertures  160  is 8 mm. The apertures  160  are circular, and the diameter of the apertures  160  is 0.1 mm. The open ends  220  of the sleeves  110  are circular, and the diameter of the open ends  220  is 4 mm. A SEM photograph of a resultant fixed abrasive wire is shown in  FIG. 5 . It is shown in the SEM photograph that the abrasive grains  180  are evenly distributed on the wire  130 . The density of the distribution of the abrasive grains  180  on the wire  130  is about 55 to 70 grain/mm 2 . 
     In another embodiment, the reaction liquid  170  is electroplating liquid including 500 grams of Ni(NH 2 SO 3 ) 2 .4H 2 O, 10 grams of NiCl.6H 2 O and 40 grams of H 3 BO 3 . The operative temperature is 40° C. to 50° C. The pH value is 3.8 to 40. The current density is 4 A/dm 2 . The average diameter of the abrasive grains  180  is 21 μm. The stirring rate is 150 to 170 rpm. The sleeves  110  are directed vertically in the tank  150 . The apertures  160  are distributed on the tubular wall  210  of each of the sleeves  110  in an alternate manner, and the distance between any two adjacent ones of the apertures 160 is 1.5 mm. The apertures  160  are circular, and the diameter of the apertures  160  is 1.8 mm. The open ends  220  of the sleeves  110  are circular, and the diameter of the open ends  220  is 4 mm. A SEM photograph of a resultant fixed abrasive wire is shown in  FIG. 6 . It is shown in the SEM photograph that the abrasive grains  180  are evenly distributed on the wire  130 . The density of the distribution of the abrasive grains  180  on the wire  130  is about 110 to 140 grain/mm 2 . 
     In another embodiment, the reaction liquid  170  is electroplating liquid including  600  grams of Ni(NH 2 SO 3 ) 2 .4H 2 O, 12 grams of NiCl.6H 2 O and 42 grams of H 3 BO 3 . The operative temperature is 55° C. to 60° C. The pH value is 3.8 to 40. The current density is 32 A/dm 2 . The average diameter of the abrasive grains  180  is 21 μm. The stirring rate is 150 to 170 rpm. The sleeves  110  are directed horizontally in the tank  150 . The apertures  160  are distributed on the tubular wall  210  of each of the sleeves  110  in an alternate manner, and the distance between any two adjacent ones of the apertures  160  is 1.5 mm. The apertures  160  are circular, and the diameter of the apertures  160  is 1.8 mm. The open ends  220  of the sleeves  110  are circular, and the diameter of the open ends  220  is 4 mm. A SEM photograph of a resultant fixed abrasive wire is shown in  FIG. 7 . It is shown in the SEM photograph that the abrasive grains  180  are evenly distributed on the wire  130 . The density of the distribution of the abrasive grains  180  on the wire  130  is about 200 to 280 grain/mm 2 . 
     The present invention has been described via the detailed illustration of the embodiments. Those skilled in the art can derive variations from the embodiments without departing from the scope of the present invention. Therefore, the embodiments shall not limit the scope of the present invention defined in the claims.