Patent Publication Number: US-7900807-B2

Title: Conductive ball mounting apparatus and conductive ball mounting method

Description:
This is a divisional application of copending application Ser. No. 12/042,916, filed on Mar. 5, 2008, which is incorporated by reference herein in its entirety. 
    
    
     This application is based on and claims priority from Japanese Patent Applications No. 2007-057785, filed on Mar. 7, 2007, No. 2007-137939, filed on May 24, 2007, and No. 2008-37732, filed on Feb. 19, 2008, the entire contents Of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present disclosure relates to a conductive ball mounting apparatus and a conductive ball mounting method and, more particularly, a conductive ball mounting apparatus and a conductive ball mounting method for mounting conductive balls on a substrate such as a wiring substrate, a wafer, or the like having a plurality of pads on which an adhesive is formed thereon. 
     2. Background Art 
       FIG. 1  to  FIG. 6  are step views describing a conductive ball mounting method in the related-art. 
     A conductive ball mounting method in the related-art will be described with reference to  FIG. 1  to  FIG. 6  hereunder. At first, in steps shown in  FIG. 1 , a flux  102  is formed on a plurality of pads  101  provided on a substrate  100 , and also a resist film  103  is formed on portions of the substrate  100  positioned between a plurality of pads  101 . 
     Then, in steps shown in  FIG. 2 , the mask  106  having a plurality of openings  106 A is fixed on the resist film  103 . The openings  106 A are formed to expose the pads  101 . 
     Then, in steps shown in  FIG. 3 , a plurality of conductive balls  108  are disposed on the mask  106 . Then, in steps shown in  FIG. 4 , one conductive ball  108  is mounted on the pads  101  on which the flux  102  is formed respectively by vibrating the substrate  100 . 
     Then, in steps shown in  FIG. 5 , extra conductive balls  108  that have not been mounted on the pads  101  are removed by sweeping an upper surface of the mask  106  by a squeegee  110 . Then, in steps shown in  FIG. 6 , the mask  106  is removed. Accordingly, the substrate  100  having the conductive balls  108  on the pads  101  is formed (see e.g., JP-A-11-297886). 
     However, in the method of mounting the conductive ball  108  in the related-art, the step of mounting one conductive ball  108  on the pads  101  on which the flux  102  is formed respectively and the step of removing the extra conductive balls  108  by sweeping an upper surface of the mask  106  by the squeegee  110  are performed separately. Therefore, such a problem existed that it is difficult to improve productivity in the step of mounting the conductive ball  108  on the pads  101  and the step of removing the extra conductive balls  108 . 
     In addition, Japanese Patent Application Publication: JP-A-2-102538 discloses another conductive ball mounting method. In JP-A-2-102538, a conductive layer on which a solder bump is formed is formed on one surface of a circuit substrate and also a solder-flux layer is formed on the one surface of the circuit substrate. Then, a spacer is formed on the solder-flux layer and a mask having openings is formed on the spacer. Next, the circuit substrate is disposed on a solder ball container for accommodating solder balls such that the one surface of the circuit substrate opposes to an opening formed in the solder ball container. Finally, the solder balls are mounted on the circuit substrate by vibrating the solder ball container hard (see FIG. 1 of JP-A-2-102538). 
     However, in the conductive ball mounting method disclosed in the related-art, rapid vibration is required to mount the solder balls on the openings of the mask. In this case, force caused by the rapid vibration is also applied to the circuit substrate (the mask). Especially, upon using a large substrate, a thin substrate or small balls whose diameter is 100 μm or less, thickness of the mask becomes thin and thus the mask is more likely to vibrate. Therefore, defect such as displacement of the solder balls is generated by vibration of the mask (the circuit substrate). 
     SUMMARY OF THE INVENTION 
     One or more exemplary embodiments of the present invention provide a conductive ball mounting apparatus and a conductive ball mounting method that can improve productivity by reducing a processing time required for the step of mounting a conductive ball on a plurality of pads respectively and the step of removing extra conductive balls. 
     According to one or more aspects of the present invention, a conductive ball mounting apparatus for mounting one conductive ball on each of a plurality of pads which are provided on a substrate and on which an adhesive is formed, the conductive ball mounting apparatus comprises: 
     a conductive ball container for containing a plurality of conductive balls therein and having an opening to pass through the plurality of conductive balls; 
     a substrate holder disposed over the conductive ball container to face the opening, and holding the substrate in such a manner that the plurality of conductive balls and the plurality of pads face each other and the substrate is disposed over the conductive ball container with a space therebetween; and 
     a conductive ball supplying unit for supplying the plurality of conductive balls to the plurality of pads via the opening by moving up the plurality of conductive balls. 
     According to the present invention, the extra conductive balls, which are not disposed on the pads on which the adhesive is formed, out of the plurality of moved-up conductive balls fall down on the conductive ball container. Therefore, the step of mounting the conductive ball on the plurality of pads respectively and the step of removing extra conductive balls can be carried out simultaneously. As a result, a processing time required for the step of mounting the conductive ball on the plurality of pads respectively and the step of removing the extra conductive balls can be shortened, and thus productivity can be improved. 
     According to one or more aspects of the present invention, a conductive ball mounting apparatus for mounting one conductive ball on each of a plurality of pads which are provided on a substrate and on which an adhesive is formed, the conductive ball mounting apparatus comprises: 
     a conductive ball for container for containing a plurality of conductive balls therein and having an opening to pass through the plurality of conductive balls; 
     a substrate holder for holding the substrate such that the plurality of conductive balls and the plurality of pads face each other in a direction perpendicular to a gravity direction; and 
     a conductive ball supplying unit for supplying the plurality of conductive balls to the plurality of pads by spraying the plurality of conductive balls. 
     According to the present invention, the extra conductive balls, which are not disposed on the pads on which the adhesive is formed respectively, out of the plurality of conductive balls sprayed to the plurality of pads fall down in the gravity direction. Therefore, the step of mounting the conductive ball on the plurality of pads respectively and the step of removing the extra conductive balls can be performed at the same time. As a result, a processing time required for the step of mounting the conductive ball on the plurality of pads respectively and the step of removing the extra conductive balls can be shortened, and productivity can be improved. 
     According to one or more aspects of the present invention, a mask may have a plurality of through portions corresponding to positions where the plurality of pads are formed, and the mask may be provided to the substrate such that each of the pads is exposed from the plurality of through portions, and a diameter of the through portions may be set to a size capable of passing only one conductive ball. 
     Therefore, it can be prevented that the plurality of conductive balls are mounted on one pad. 
     According to one or more aspects of the present invention, the conductive ball mounting apparatus further comprises: 
     a potential difference generating unit for generating a potential difference between the plurality of conductive balls contained in the conductive ball container and the substrate. 
     Therefore, the plurality of moved-up conductive balls supplied by the conductive ball supplying unit are attracted to the substrate by an electrical attractive force. As a result, a processing time in the step of mounting one conductive ball on a plurality of pads respectively can be shortened. 
     According to one or more aspects of the present invention, the conductive ball mounting apparatus further comprises: 
     a charging unit for charging the mask up to a potential that is substantially equal to a potential of the plurality of conductive balls contained in conductive ball container. 
     Therefore, the plurality of raised conductive balls are attracted to the pads by an electrical attractive force. As a result, a processing time in the step of mounting the conductive ball on the plurality of pads respectively can be further shortened. 
     According to one or more aspects of the present invention, the conductive ball mounting apparatus further comprises: 
     a conductive ball recovering container for recovering extra conductive balls that are not disposed on the pads and fall down in the gravity direction, the conductive ball recovering container being disposed below the substrate in the gravity direction. 
     According to one or more aspects of the present invention, a method for mounting one conductive ball on each of a plurality of pads which are provided on a substrate and on which an adhesive is formed, the method comprises the successive steps of: 
     (a) disposing the substrate over a conductive ball container for containing the plurality of conductive balls therein with a space therebetween such that the plurality of conductive balls and the plurality of pads face each other; and 
     (b) supplying the plurality of conductive balls to the plurality of pads by moving up the plurality of conductive balls. 
     According to the present invention, the extra conductive balls, which are not disposed on the pads on which the adhesive is formed, out of the plurality of moved-up conductive balls fall down on the conductive ball container. Therefore, the step of mounting the conductive ball on the plurality of pads respectively and the step of removing extra conductive balls can be carried out at the same time. As a result, a processing time required for the step of mounting the conductive ball on the plurality of pads respectively and the step of removing the extra conductive balls can be shortened, and thus productivity can be improved. 
     According to one or more aspects of the present invention, a method for mounting one conductive ball on each of a plurality of pads which are provided on a substrate and on which an adhesive is formed, the method comprises the successive steps of: 
     (a) disposing the substrate such that a plurality of conductive balls and the plurality of pads face each other in a direction perpendicular to a gravity direction; and 
     (b) supplying the plurality of conductive balls to the plurality of pads by spraying the plurality of conductive balls. 
     According to the present invention, the extra conductive balls, which are not disposed on the pads on which the adhesive is formed respectively, out of the plurality of conductive balls sprayed to the mask fall in the gravity direction. Therefore, the step of mounting the conductive ball on the plurality of pads respectively and the step of removing the extra conductive balls can be performed simultaneously. As a result, a processing time required for the step of mounting the conductive ball on the plurality of pads respectively and the step of removing the extra conductive balls can be shortened, and productivity can be improved. 
     According to one or more aspects of the present invention, the method further comprises: 
     (c) providing a mask having a plurality of through portions corresponding to positions where a plurality of pads are formed, before step (a). 
     According to one or more aspects of the present invention, the method further comprises: 
     (d) providing a mask having a plurality of through portions such that the mask covers an opening of a conductive ball container where the plurality of conductive balls are contained, before step (a). 
     According to one or more aspects of the present invention, the method further comprises: 
     (e) generating a potential difference between the plurality of conductive balls contained in the conductive ball container and the substrate, between step (a) and step (b). 
     Therefore, the plurality of conductive balls are attracted to the substrate by an electrical attractive force. As a result, a processing time in the step of mounting one conductive ball on the plurality of pads respectively can be shortened. 
     According to one or more aspects of the present invention, the method further comprises: 
     (f) charging the mask up to a potential that is substantially equal to a potential of the plurality of conductive balls contained in the conductive ball container, between step (a) and step (b). 
     Therefore, the plurality of conductive balls are attracted to the pads by an electrical attractive force. As a result, a processing time in the step of mounting the conductive ball on the plurality of pads respectively can be further shortened. 
     According to one or more exemplary embodiments of the present invention, productivity can be improved by reducing a processing time in the step of mounting conductive balls on a plurality of pads and the step of removing extra conductive balls. 
     According to one or more exemplary embodiments of the present invention, the substrate is disposed over the conductive ball container with a space therebetween, so that defect such as displacement of solder balls can be suppressed. 
     Other aspects and advantages of the invention will be apparent from the following description, the drawings and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a step view (# 1 ) describing a conductive ball mounting method in the related-art; 
         FIG. 2  is a step view (# 2 ) describing the conductive ball mounting method in the related-art; 
         FIG. 3  is a step view (# 3 ) describing the conductive ball mounting method in the related-art; 
         FIG. 4  is a step view (# 4 ) describing the conductive ball mounting method in the related-art; 
         FIG. 5  is a step view (# 5 ) describing the conductive ball mounting method in the related-art; 
         FIG. 6  is a step view (# 6 ) describing the conductive ball mounting method in the related-art; 
         FIG. 7  is a sectional view of a conductive ball mounting apparatus according to a first embodiment of the present invention; 
         FIG. 8  is a step view (# 1 ) describing a conductive ball mounting method using the conductive ball mounting apparatus according to the first embodiment of the present invention; 
         FIG. 9  is a step view (# 2 ) describing the conductive ball mounting method using the conductive ball mounting apparatus according to the first embodiment of the present invention; 
         FIG. 10  is a step view (# 3 ) describing the conductive ball mounting method using the conductive ball mounting apparatus according to the first embodiment of the present invention; 
         FIG. 11  is a step view (# 4 ) describing the conductive ball mounting method using the conductive ball mounting apparatus according to the first embodiment of the present invention; 
         FIG. 12  is a step view (# 5 ) describing the conductive ball mounting method using the conductive ball mounting apparatus according to the first embodiment of the present invention; 
         FIG. 13  is a step view (# 6 ) describing the conductive ball mounting method using the conductive ball mounting apparatus according to the first embodiment of the present invention; 
         FIG. 14  is a step view (# 7 ) describing the conductive ball mounting method using the conductive ball mounting apparatus according to the first embodiment of the present invention; 
         FIG. 15  is a sectional view of a conductive ball mounting apparatus according to a second embodiment of the present invention; 
         FIG. 16  is a sectional view of a conductive ball mounting apparatus according to a third embodiment of the present invention; 
         FIG. 17  is a sectional view of a conductive ball mounting apparatus according to a fourth embodiment of the present invention; 
         FIG. 18  is a sectional view of a conductive ball mounting apparatus according to a fifth embodiment of the present invention; and 
         FIG. 19  is a sectional view of a conductive ball mounting apparatus according to a sixth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments of the present invention will be described with reference to the drawings hereinafter. 
     First Embodiment 
       FIG. 7  is a sectional view of a conductive ball mounting apparatus according to a first embodiment of the present invention. In  FIG. 7 , such a situation is illustrated that a plurality of conductive balls  14  are caused to move up the lower side of a substrate  18  held by a substrate holder  15 . Also, in  FIG. 7 , Z direction denotes the vertical direction, and X direction denotes the direction that intersects orthogonally with the Z direction. 
     By reference to  FIG. 7 , a conductive ball mounting apparatus  10  of the first embodiment includes a stage  11 , a vibrating unit  12  as a conductive ball supplying unit, a conductive ball container  13 , a plurality of conductive balls  14 , and the substrate holder  15  for holding the substrate  18 . 
     At first, for brief description, a structure of the substrate  18  held by the substrate holder  15  will be described hereunder. The substrate  18  is constructed such that a plurality of substrates  25  are formed on a plate-like substrate main body  26 . That is, the substrate  18  is an aggregate of the plurality of substrates  25  prior to diving into individual pieces. As the substrate main body  26 , a glass epoxy resin may be used. 
     The substrate  25  has the substrate main body  26 , through vias  28 , upper wirings  29 , pads  31 ,  35 , solder resists  32 ,  37 , lower wirings  34 , and adhesives  38 . The through via  28  is provided to pass through the substrate main body  26 . An upper end portion of the through via  28  is connected to the pad  31 , and a lower end portion of the through via  28  is connected to the pad  35 . 
     The upper wirings  29  are provided on an upper surface  26 A of the substrate main body  26 . The upper wirings  29  are connected to the pads  31 . The pads  31  are provided on portions, which correspond to positions where the through via  28  is formed, of the upper surface  26 A of the substrate main body  26 . The pad  31  is connected to the through vias  28  respectively. The pads  31  are provided to mount an electronic component (e.g., a passive component, or the like). The solder resist  32  is provided on the upper surface  26 A of the substrate main body  26  to cover the upper wirings  29 . The solder resist  32  has openings  32 A to expose the pads  31 . 
     The lower wirings  34  are provided on a lower surface  26 B of the substrate main body  26 . The lower wirings  34  are connected to the pads  35 . The pads  35  are provided on portions, which correspond to positions where the through via  28  is formed, of the lower surface  26 B of the substrate main body  26 . The pad  35  is connected to the through vias  28  respectively. The pads  35  are connected electrically to the pads  31  via the through vias  28 . One conductive ball  14  serving as an external connection terminal of the substrate  25  is provided on the pad  35  via the adhesive  38 . 
     The solder resist  37  is provided on the lower surface  26 B of the substrate main body  26  to cover the lower wirings  34 . The solder resist  37  has openings  37 A to expose the pads  35 . The adhesive  38  is provided on the pads  35  to fill the openings  37 A. The adhesive  38  is used to temporarily fix the conductive balls  14  that are caused to move up when the vibrating unit  12  vibrates the conductive ball container  13 . As the adhesive  38 , the flux, the solder paste may be used. 
     The substrate  18  constructed as above is held by the substrate holder  15  such that a plurality of pads  35  on which the adhesive  38  is formed respectively are opposed to a plurality of conductive balls  14  exposed from openings  13 A. 
     The stage  11  supports the conductive ball container  13  via the vibrating unit  12 . The vibrating unit  12  is provided on the stage  11 . The vibrating unit  12  vibrates the conductive ball container  13  containing a plurality of conductive balls  14  to move up the plurality of conductive balls  14 , and thus supplies the plurality of conductive balls  14  to the substrate  18  arranged over the conductive ball container  13 . 
     Since such the vibrating unit  12  moves up the plurality of conductive balls  14  from the lower side of the substrate  18 , extra conductive balls  14 , which are not disposed on the pads  35  on which the adhesive  38  is formed, out of the plurality of moved up conductive balls  14  fall down on the conductive ball container  13 . Therefore, the step of mounting the conductive ball  14  on the plurality of pads  35  respectively and the step of removing extra conductive balls  14  can be performed at the same time. As a result, a processing time required for the step of mounting the conductive ball  14  on the plurality of pads  35  respectively and the step of removing the extra conductive balls  14  can be shortened, and productivity can be improved. 
     The conductive ball container  13  is provided to contain the plurality of conductive balls  14 . The opening  13 A for passing the plurality of conductive balls  14  moved up by the vibrating unit  12  through there is formed on the upper end portion of the conductive ball container  13 . The plurality of conductive balls  14  passing through the conductive ball container  13  reach the substrate  18  and are disposed on the pads  35  on which the adhesive  38  is formed respectively. As the material of the conductive ball container  13 , a metal may be used. 
     A plurality of conductive balls  14  are contained in the conductive ball container  13 . The conductive balls  14  act as the external connection terminals of the substrate  25 . As the conductive ball  14 , a solder ball may be used. Also, when the solder ball is used as the conductive ball  14 , a diameter of the conductive ball  14  may be set to 10 μm to 100 μm, for example. 
     The substrate holder  15  is disposed over the conductive ball container  13 . The substrate holder  15  has a substrate holding portion  21 , and a support  22 . The substrate holding portion  21  is disposed such that its lower surface  21 A faces the opening  13 A of the conductive ball container  13 . The substrate holding portion  21  is formed into a plate shape. The substrate holding portion  21  holds the substrate  18  on its lower surface  21 A. As the method of holding the substrate  18 , suction, mechanical holding (e.g., clamping) may be used. Also, a distance D 1  between the adhesives  38  of the substrate  18  held by the substrate holding portion  21  and the plurality of conductive balls  14  contained in the conductive ball container  13  may be set to 1 mm, for example. The support  22  is provided to support the substrate holding portion  21 . 
     According to the present embodiment, the conductive ball mounting apparatus includes: the conductive ball container  13  for containing a plurality of conductive balls  14  therein and also having the opening  13 A to supply the plurality of conductive balls  14 ; the substrate holder  15  disposed over the conductive ball container  13  to face the opening  13 A and for holding the substrate  18  such that a plurality of conductive balls  14  and a plurality of pads  35  are opposed to each other; and the vibrating unit  12  for moving up the plurality of conductive balls  14 . Thus, the extra conductive balls  14 , which are not disposed on the pads  35  on which the adhesive  38  is formed, out of the plurality of moved-up conductive balls  14  fall down on the conductive ball container  13 . Therefore, the step of mounting the conductive ball  14  on the plurality of pads  35  respectively and the step of removing extra conductive balls  14  may be carried out simultaneously. As a result, a processing time required for the step of mounting the conductive ball  14  on the plurality of pads  35  respectively and the step of removing the extra conductive balls  14  can be shortened, and thus productivity can be improved. 
       FIG. 8  to  FIG. 14  are step views describing a conductive ball mounting method using the conductive ball mounting apparatus according to the first embodiment of the present invention. In  FIG. 8  to  FIG. 14 , the same reference symbols are denoted to the same constituent portions as the configuration shown in  FIG. 7 . Also, in  FIG. 8 ,  FIG. 13 , and  FIG. 14 , “A” denotes a position where the substrate  18  is divided into individual pieces (referred to as a “cut position A” hereinafter). 
     The method of mounting the conductive balls  14  using the conductive ball mounting apparatus  10  according to the first embodiment of the present invention will be described with reference to  FIG. 8  to  FIG. 14  hereunder. 
     At first, in steps shown in  FIG. 8 , the substrate  18  where the adhesive  38  is provided on a plurality of pads  35  respectively is formed by the well-known approach. Then, in steps shown in  FIG. 9 , a plurality of conductive balls  14  are filled in the conductive ball container  13 . 
     Then, in steps shown in  FIG. 10 , the substrate  18  is held by the substrate holding portion  21  such that the substrate  18  is disposed over the conductive ball container  13  with a space therebetween. The substrate holding portion  21  is disposed over the plurality of conductive balls  14  such that the plurality of conductive balls  14  and the plurality of pads  35  on which the adhesive  38  is provided respectively face each other (substrate disposing step). 
     Then, in steps shown in  FIG. 11 , the plurality of conductive balls  14  are provided to the plurality of pads  35  by vibrating the conductive ball container  13  by means of the vibrating unit  12  to move up the plurality of conductive balls  14  contained in the conductive ball container  13  (conductive ball providing step). 
     Accordingly, the extra conductive balls  14 , which are not disposed on the pads  35  on which the adhesive  38  is formed, out of the plurality of raised conductive balls  14  fall down on the conductive ball container  13 . Therefore, the step of mounting the conductive ball  14  on the plurality of pads  35  respectively and the step of removing extra conductive balls  14  can be carried out simultaneously. As a result, a processing time required for the step of mounting the conductive ball  14  on the plurality of pads  35  respectively and the step of removing the extra conductive balls  14  can be shortened, and thus productivity can be improved. 
     In this case, the vibration of the conductive ball container  13  by the vibrating unit  12  is continued until the conductive ball  14  is mounted on all pads  35  respectively. 
     Then, in steps shown in  FIG. 12 , the vibration of the conductive ball container  13  by the vibrating unit  12  is stopped after the conductive ball  14  is mounted on all pads  35  respectively. 
     Then, in steps shown in  FIG. 13 , the substrate  18  on which the conductive balls  14  are mounted is released from the substrate holding portion  21 . Then, the conductive balls  14  and the pads  35  are joined together by heating a structure shown in  FIG. 13 , and then the adhesive  38  is cleaned. 
     Then, in steps shown in  FIG. 14 , the structure shown in  FIG. 13  is cut along the cut position A. As a result, a plurality of substrates  25  having the conductive balls  14  are formed. 
     According to the conductive ball mounting method of the present embodiment, the plurality of conductive balls  14  are moved up to the lower side of the substrate  18  being held such that the plurality of conductive balls  14  and a plurality of pads  35  on which the adhesive  38  is provided respectively face each other. Thus, the extra conductive balls  14 , which are not disposed on the pads  35  on which the adhesive  38  is formed, out of the plurality of raised conductive balls  14  fall down on the conductive ball container  13 . Therefore, the step of mounting the conductive ball  14  on the plurality of pads  35  respectively and the step of removing extra conductive balls  14  can be carried out at the same time. As a result, a processing time required for the step of mounting the conductive ball  14  on the plurality of pads  35  respectively and the step of removing the extra conductive balls  14  can be shortened, and thus productivity can be improved. 
     In the present embodiment, the case where the vibrating unit  12  is used as the conductive ball supplying unit is described by way of example. But any means may be employed as the conductive ball supplying unit if such means can move up the plurality of conductive balls  14 . For example, in place of the vibrating unit  12 , an air supplying unit for moving up the plurality of conductive balls  14  by supplying an air may be employed. 
     Second Embodiment 
       FIG. 15  is a sectional view of a conductive ball mounting apparatus according to a second embodiment of the present invention. In  FIG. 15 , such a situation is illustrated that a plurality of conductive balls  14  are moved up to the lower side of the substrate  18  held by the substrate holder  15 . Also, in  FIG. 15 , the same reference symbols are denoted to the same constituent portions as those of the conductive ball mounting apparatus  10  in the first embodiment. 
     By reference to  FIG. 15 , a conductive ball mounting apparatus  45  of the second embodiment is constructed similarly to the conductive ball mounting apparatus  10  except that a mask  46  is provided to the configuration of the conductive ball mounting apparatus  10  in the first embodiment. Also, the mask  46  is disposed over the conductive ball container  13  with a space therebetween. 
     The mask  46  is fixed to the substrate  18  via a resist film  47  formed on the solder resist  37 . The mask  46  has through portions  46 A. A plurality of through portions  46 A are formed to pass through portions, which correspond to positions where the pad  35  is formed respectively, of the mask  46 . The through portions  46 A are formed to expose the pads  35 . A diameter R 1  of the through portion  46 A is set to a size through which only one conductive ball  14  can pass (a size larger slightly than a diameter of the conductive ball  14 ). Concretely, when a diameter of the conductive ball  14  is 100 μm, a diameter R 1  of the through portion  46 A can be set to 120 μm, for example. Also, the material of the mask  46 , a metal may be used. 
     According to the conductive ball mounting apparatus of the present embodiment, the mask  46  having the plurality of through portions  46 A in portions corresponding to positions where a plurality of pads  35  are formed is fixed to the substrate  18 , and also a diameter R 1  of the through portion  46 A is set to a size through which only one conductive ball  14  can pass. Therefore, such a situation can be prevented that the plurality of conductive balls  14  are disposed on one pad  35  on which the adhesive  38  is formed. 
     When the conductive ball mounting apparatus  45  of the present embodiment is used, the conductive ball  14  can be mounted on the plurality of pads  35  respectively by the similar approach to the method of mounting the conductive ball  14  described in the first embodiment. 
     According to the conductive ball mounting method of the present invention, the mask  46  having the plurality of through portions  46 A in portions corresponding to positions where the plurality of pads  35  are formed is fixed to the substrate  18 , and then the plurality of conductive balls  14  are moved up. Therefore, a diameter R 1  of the through portion  46 A is set to a size through which only one conductive ball  14  can pass. As a result, such a situation can be prevented that the plurality of conductive balls  14  are mounted on one pad  35  on which the adhesive  38  is formed. 
     Also, such a situation can be prevented by using the mask  46  that the plurality of conductive balls  14  come into collision with respective portions of the substrate  18  on which the adhesive  38  is not formed. Therefore, it can be prevented that the substrate  18  is damaged on account of the collision of the conductive ball  14 . 
     Third Embodiment 
       FIG. 16  is a sectional view of a conductive ball mounting apparatus according to a third embodiment of the present invention. In  FIG. 16 , such a situation is illustrated that a plurality of conductive balls  14  are moved up to the lower side of the substrate  18  held by the substrate holder  15 . Also, in  FIG. 16 , the same reference symbols are denoted to the same constituent portions as those of the conductive ball mounting apparatus  45  in the second embodiment. 
     By reference to  FIG. 16 , a conductive ball mounting apparatus  50  according to the third embodiment is constructed similarly to the conductive ball mounting apparatus  45  except that a potential difference generating unit  51  and insulating members  52 A,  52 B are provided to the configuration of the conductive ball mounting apparatus  45  in the second embodiment. 
     The potential difference generating unit  51  has a power supply  54  and wirings  56  to  58 . The power supply  54  has a plus terminal  54 A and a minus terminal  54 B. The plus terminal  54 A is connected electrically to the substrate  18  via the wiring  56 . Accordingly, the substrate  18  is set to a plus potential. The minus terminal  54 B is connected to a ground via the wiring  57 . Accordingly, the minus terminal  54 B is set to a ground potential. 
     One end portion of the wiring  56  is connected to the substrate  18  whereas the other end is connected to the plus terminal  54 A. One end portion of the wiring  57  is connected to the minus terminal  54 B whereas the other end is connected to a ground. One end portion of the wiring  58  is connected to the wiring  57  whereas the other end is connected to the conductive ball container  13 . Accordingly, the conductive ball container  13  and a plurality of conductive balls  14  contained in the conductive ball container  13  are set to a ground potential. 
     The potential difference generating unit  51  constructed as above is provided to generate a potential difference between the plurality of conductive balls  14  contained in the conductive ball container  13  and the substrate  18 . A potential difference generated between a plurality of conductive balls  14  and the substrate  18  may be set such that an electrical attractive force generated between the plurality of conductive balls  14  and the substrate  18  by the potential difference exceeds a gravity applied to the conductive balls  14 . Concretely, the potential difference generated between the plurality of conductive balls  14  and the substrate  18  may be set to several hundreds V to tens of thousands V, for example. 
     In this manner, the potential difference generating unit  51  for generating a potential difference between the plurality of conductive balls  14  contained in the conductive ball container  13  and the substrate  18  is provided. Thus, the plurality of moved-up conductive balls  14  are attracted to the substrate  18  by an electrical attractive force. As a result, a processing time in the step of mounting the conductive ball  14  on the plurality of pads  35  respectively can be shortened. 
     The insulating member  52 A is provided between the vibrating unit  12  and the conductive ball container  13 . The insulating member  52 A is provided to make the charging of the plurality of conductive balls  14  contained in the conductive ball container  13  easy. The insulating member  52 B is provided between the substrate holding portion  21  and the support  22 . The insulating member  52 B is provided to insulate the substrate holding portion  21  and the support  22  mutually. 
     According to the conductive ball mounting apparatus of the present embodiment, the potential difference generating unit  51  for generating the potential difference between the plurality of conductive balls  14  contained in the conductive ball container  13  and the substrate  18  is provided. Thus, the plurality of moved-up conductive balls  14  are attracted to the substrate  18  by an electrical attractive force. As a result, a processing time required for the step of mounting the conductive ball  14  on a plurality of pads  35  respectively can be reduced. 
     When the conductive ball mounting apparatus  50  of the present embodiment is used, the conductive ball  14  can be mounted on the plurality of pads  35  respectively by the similar approach to the method of mounting the conductive ball  14  in the first embodiment, except that a potential difference is generated between the plurality of conductive balls  14  contained in the conductive ball container  13  and the substrate  18  (the potential difference generating step) in the steps shown in  FIG. 10  and  FIG. 11  in the first embodiment. 
     According to the conductive ball mounting method of the present embodiment, the plurality of conductive balls  14  are moved up after a potential difference is generated between the plurality of conductive balls  14  contained in the conductive ball container  13  and the substrate  18  (the potential difference generating step). Therefore, the plurality of raised conductive balls  14  are attracted to the substrate  18  by an electrical attractive force. As a result, a processing time in the step of mounting the conductive ball  14  on the plurality of pads  35  respectively can be reduced. 
     In the present embodiment, the case where the plurality of conductive balls  14  contained in the conductive ball container  13  are set to a ground potential and the substrate  18  is set to a plus potential is described as an example. But the substrate  18  may be set to a ground potential and the plurality of conductive balls  14  may be set to a plus potential. 
     Fourth Embodiment 
       FIG. 17  is a sectional view of a conductive ball mounting apparatus according to a fourth embodiment of the present invention. In  FIG. 17 , such a situation is illustrated that a plurality of conductive balls  14  are moved up to the lower side of the substrate  18  held by the substrate holder  15 . Also, in  FIG. 17 , the same reference symbols are denoted to the same constituent portions as those of the conductive ball mounting apparatus  50  in the third embodiment. 
     By reference to  FIG. 17 , a conductive ball mounting apparatus  60  of the fourth embodiment is constructed similarly to the conductive ball mounting apparatus  50  except that a charging unit  61  is further provided to the configuration of the conductive ball mounting apparatus  50  in the third embodiment. In the present embodiment, the case where a wiring is used as the charging unit  61  will be described below. 
     One end portion of the charging unit  61  is connected to the wiring  57  whereas the other end portion is connected to the mask  46 . Accordingly, the mask  46  is set to a ground potential that is substantially equal to a potential of the plurality of conductive balls  14  contained in the conductive ball container  13 . 
     According to the conductive ball mounting apparatus, there are provided the potential difference generating unit  51  for generating a potential difference between the plurality of conductive balls  14  contained in the conductive ball container  13  and the substrate  18  and the charging unit  61  for making a potential of the mask  46  substantially equal to a potential of the plurality of conductive balls  14  contained in the conductive ball container  13 . Therefore, the plurality of moved-up conductive balls  14  are attracted to the pads  35  by an electrical attractive force. As a result, a processing time in the step of mounting the conductive ball  14  on the plurality of pads  35  respectively can be further shortened. 
     When the conductive ball mounting apparatus  60  of the present embodiment is used, the conductive ball  14  can be mounted on the plurality of pads  35  respectively by the similar approach to the method of mounting the conductive ball  14  in the first embodiment except that a potential difference is generated between the plurality of conductive balls  14  contained in the conductive ball container  13  and the substrate  18  (the potential difference generating step) and a potential of the mask  46  is made substantially equal to a potential of the plurality of conductive balls  14  contained in the conductive ball container  13  (the mask charging step), in the steps shown in  FIG. 10  and  FIG. 11  in the first embodiment. 
     According to the conductive ball mounting method of the present embodiment, the plurality of conductive balls  14  are moved up after a potential difference is generated between the plurality of conductive balls  14  contained in the conductive ball container  13  and the substrate  18  (the potential difference generating step) and a potential of the mask  46  is made substantially equal to a potential of the plurality of conductive balls  14  contained in the conductive ball container  13  (the mask charging step). Therefore, the plurality of moved-up conductive balls  14  are attracted to the pads  35  by an electrical attractive force. As a result, a processing time in the step of mounting the conductive ball  14  on the plurality of pads  35  respectively can be further reduced. 
     Fifth Embodiment 
       FIG. 18  is a sectional view of a conductive ball mounting apparatus according to a fifth embodiment of the present invention. In  FIG. 18 , such a situation is illustrated that a plurality of conductive balls  14  are sprayed to the substrate  18 , on which the mask  46  is provided, from the direction that intersects orthogonally with the vertical direction (Z-direction). Also, in  FIG. 18 , the same reference symbols are denoted to the same constituent portions as those of the conductive ball mounting apparatus  45  in the second embodiment. 
     By reference to  FIG. 18 , a conductive ball mounting apparatus  70  of the fifth embodiment is constructed similarly to the conductive ball mounting apparatus  45 , except that a supporting table  71 , a conductive ball container  72 , an air supplying unit  73  as the conductive ball supplying unit, and a conductive ball recovering container  74  are provided instead of the stage  11 , the vibrating unit  12 , and the conductive ball container  13  provided to the conductive ball mounting apparatus  45  of the second embodiment and except that the substrate  18  is held by the substrate holder  15  such that openings  76 A of the conductive ball container  72  and the pads  35  face each other in a direction perpendicular to the vertical direction (Z, Z direction). 
     The supporting table  71  is provided to support the conductive ball container  72  and the air supplying unit  73 . The conductive ball container  72  has a front plate  76  and a rear plate  77 . The conductive ball container  72  is disposed such that the front plate  76  faces a plurality of pads  35 . The front plate  76  has a plurality of openings  76 A. The openings  76 A are formed to pass through portions of the front plate  76 , which face to the pads  35 . When a diameter of the conductive ball  14  is 100 μm, a diameter R 2  of the opening  76 A may be set to 150 μm, for example. Also, a distance D 2  between the front plate  76  and the adhesive  38  may be set to 1 mm, for example. 
     The rear plate  77  has a plurality of air introduction ports  77 A. The air introduction ports  77 A are formed to pass through portions, which face to the openings  76 A, of the rear plate  77 . The plurality of air introduction ports  77 A are provided to introduce an air supplied from the air supplying unit  73  into the conductive ball container  72 . 
     The air supplying unit  73  is provided on the supporting table  71  and contacts the rear plate  77  of the conductive ball container  72 . The air supplying unit  73  is the unit that supplies an air into the conductive ball container  72  via the air introduction ports  77 A. The air supplying unit  73  supplies an air into the conductive ball container  72  to spray a plurality of conductive balls  14  to the substrate  18 , on which the mask  46  is provided, (concretely, the plurality of pads  35 ) via the openings  76 A in such a manner that one conductive ball  14  is mounted on the plurality of pads  35  respectively. 
     The extra conductive balls  14 , being not disposed on the pads  35  on which the adhesive  38  is formed respectively, out of the plurality of conductive balls  14  sprayed to the substrate  18  fall down in the vertical direction by virtue of gravity. Therefore, the step of mounting the conductive ball  14  on the plurality of pads  35  respectively and the step of removing the extra conductive balls  14  can be performed at the same time. As a result, a processing time required for the step of mounting the conductive ball  14  on the plurality of pads  35  respectively and the step of removing the extra conductive balls  14  can be shortened, and productivity can be improved. 
     The conductive ball recovering container  74  is disposed below the substrate  18 . An upper end portion of the conductive ball recovering container  74  is open. The conductive ball recovering container  74  is provided to recover the extra conductive balls  14  that are not disposed on the pads  35  and fall down in the vertical direction by virtue of gravity. In this manner, the recovered conductive balls  14  can be reused by providing the conductive ball recovering container  74 . 
     According to the present embodiment, the conductive ball mounting apparatus includes: the conductive ball container  72  for containing the plurality of conductive balls  14  and having the plurality of openings  76 A to supply the plurality of conductive balls  14 ; the substrate holder  15  for holding the substrate  18  such that the openings  76 A of the conductive ball container  72  and the pads  35  face each other in a direction perpendicular to the vertical direction (Z direction); and the air supplying unit  73  for spraying the plurality of conductive balls  14  to the plurality of pads  35 . Therefore, the extra conductive balls  14 , which are not disposed on the pads  35  on which the adhesive  38  is formed respectively, out of the plurality of conductive balls  14  sprayed to the substrate  18  fall down in the vertical direction by virtue of gravity. As a result, the step of mounting the conductive ball  14  on the plurality of pads  35  respectively and the step of removing the extra conductive balls  14  can be carried out simultaneously. 
     Accordingly, a processing time required for the step of mounting the conductive ball  14  on the plurality of pads  35  respectively and the step of removing the extra conductive balls  14  can be shortened, and productivity can be improved. 
     When the conductive ball mounting apparatus  70  of the present embodiment is used, the conductive ball  14  can be mounted on the plurality of pads  35  respectively by the similar approach to the method of mounting the conductive balls  14  described in the first embodiment, except that the plurality of conductive balls  14  are supplied to the substrate  18  by an air supplied from the air supplying unit  73  in the steps shown in  FIG. 11  in the first embodiment. 
     According to the conductive ball mounting method of the present embodiment, the substrate  18  is held such that the openings  76 A and the pads  35  face each other in a direction perpendicular to the vertical direction (Z direction), and then the plurality of conductive balls  14  are sprayed to the plurality of pads  35  by the air supplying unit  73 . Therefore, the extra conductive balls  14 , which are not disposed on the pads  35 , out of the plurality of conductive balls  14  sprayed to the substrate  18  fall down in the vertical direction by virtue of gravity. As a result, the step of mounting the conductive ball  14  on the plurality of pads  35  respectively and the step of removing the extra conductive balls  14  can be performed at the same time. 
     Accordingly, a time required for the step of mounting the conductive ball  14  on the plurality of pads  35  respectively and the step of removing the extra conductive balls  14  can be reduced shorter than the related-art. As a result, productivity can be improved in the step of mounting the conductive ball  14  on the plurality of pads  35  respectively and the step of removing the extra conductive balls  14 . 
     Also, the potential difference generating unit  51  (see  FIG. 16 ) described in the third embodiment may be provided to the conductive ball mounting apparatus  70  of the present embodiment. In this case, the similar advantages to those of the conductive ball mounting apparatus  50  in the third embodiment can be achieved. 
     Here, the potential difference generating unit  51  (see  FIG. 16 ) described in the third embodiment and the charging unit  61  (see  FIG. 17 ) described in the fourth embodiment may be provided to the conductive ball mounting apparatus  70  of the present embodiment. In this case, the similar advantages to those of the conductive ball mounting apparatus  60  in the fourth embodiment can be achieved. 
     Sixth Embodiment 
       FIG. 19  is a sectional view of a conductive ball mounting apparatus according to a sixth embodiment of the present invention. In  FIG. 19 , such a situation is illustrated that a plurality of conductive balls  14  are moved up to the lower side of the substrate  18  held by the substrate holder  15 . Also, in  FIG. 19 , the same reference symbols are denoted to the same constituent portions as those of the conductive ball mounting apparatus  45  in the second embodiment. 
     By reference to  FIG. 19 , a conductive ball mounting apparatus  80  of the sixth embodiment is constructed similarly to the conductive ball mounting apparatus  45 , except that a plate  81  and a containing stage  82  are provided instead of the mask  46  and the stage  11  provided to the conductive ball mounting apparatus  45  in the second embodiment and except that the resist film  47  provided in the conductive ball mounting apparatus  45  is removed from the constituent elements. 
     The containing stage  82  has a containing portion  82 A to contain the vibrating unit  12  and the conductive ball container  13  therein. The containing stage  82  contacts the lower end portion of the vibrating unit  12 . The containing stage  82  supports the conductive ball container  13  via the vibrating unit  12 . 
     The plate  81  is provided to the containing stage  82 , and is disposed over the conductive ball container  13 . The plate  81  has a plurality of through portions  81 A. The through portions  81 A are formed to pass through portions, which face to the pads  35 , of the plate  81 . The plate  81  having the plurality of through portions  81 A is the mask used to emit the conductive balls  14  toward the adhesive  38  being formed on the pads  35  respectively. When a diameter of the conductive ball  14  is 100 μm, a diameter of the through portion  81 A may be set to 120 μm, for example. As the material of the plate  81 , a metal may be used. 
     According to the conductive ball mounting apparatus of the present embodiment, the containing stage  82  for containing the vibrating unit  12  and the conductive ball container  13  therein is provided, and also the plate  81  having the through portions  81 A that emit the conductive balls  14  toward the adhesive  38  being formed on the pads  35  respectively is provided to the containing stage  82 . Therefore, the conductive balls  14  can be mounted more easily than the case where the conductive ball  14  is mounted on the pads  35 , on which the adhesive  38  is formed respectively, by fitting the mask  46  on the substrate  18  via the resist film  47 , and also productivity can be improved in the conductive ball mounting step. 
     The method of mounting the conductive ball  14  of the present embodiment can be carried out by the similar approach to the method of mounting the conductive ball  14  of the second embodiment. The method of mounting the conductive ball  14  of the present embodiment can achieve the similar advantages to those of the method of mounting the conductive balls  14  in the second embodiment. 
     While there has been described in connection with the exemplary embodiments of the present invention, it will be obvious to those skilled in the art that various changes and modification may be made therein without departing from the present invention. It is aimed, therefore, to cover in the appended claim all such changes and modifications as fall within the true spirit and scope of the present invention. 
     The present invention is applicable to the conductive ball mounting apparatus and the conductive ball mounting method for mounting the conductive balls on the substrate having the plurality of pads on which an adhesive is formed thereon.