Patent Document

TECHNICAL FIELD 
       [0001]    The present invention relates to an electronic component and its lead-wire, and a method for manufacturing the lead-wire as well as the electronic component using the lead-wire, particularly the present invention relates to a capacitor having a sealing member through which the lead-wire extends. 
       BACKGROUND ART 
       [0002]      FIG. 17  shows a sectional view of an aluminum electrolytic capacitor, i.e. one of conventional electronic components.  FIG. 18  shows a perspective view of a lead-wire to be used in the aluminum electrolytic capacitor.  FIG. 19  shows a sectional view of the lead-wire. 
         [0003]    As shown in  FIG. 17 , the aluminum electrolytic capacitor is formed of capacitor element  6 , which works as a functional element, lead-wire  1 , housing  7 , and sealing member  8 . Lead-wire  1  is led out of capacitor element  6 , and housing  7  shaped like a cylinder with a bottom accommodates capacitor element  6 . Sealing member  8  is provided with through-holes  8   a  through which lead-wires  1  run. Sealing member  8  is placed at the opening of housing  7 , and it is drawn at drawn section  7   a  provided on the outer wall of housing  7 , whereby the opening of housing  7  is sealed. 
         [0004]    As shown in  FIG. 18 , lead-wire  1  is formed of led-out electrode  2  made of aluminum round bar, cap  4 , and flat section  2   e . As shown in  FIG. 19 , cap  4  is put over first end  2   a  of led-out electrode  2 . Flat section  2   e  is formed by pressing a second end of led-out electrode  2  into a flat shape, and is coupled to capacitor element  6 . Cap  4  covering first end  2   a  works as a terminal to be coupled to circuit board  10 , and it is made of the material ready to be soldered. 
         [0005]    The aluminum electrolytic capacitor discussed above uses lead-wire  1  of which cap  4  covering first end  2   a  works as a terminal, so that malformations at a junction between first end  2   a  and the terminal can be reduced comparing with the malformations occurring when first end  2   a  is directly melted to a wire-like terminal. Quality of the aluminum electrolytic capacitor thus can be controlled with ease, and the highly reliable capacitor stable in bonding quality can be thus obtained. The aluminum electrolytic capacitor discussed above is disclosed in, e.g. patent literature 1. 
         [0006]    However, in the case of fitting cap  4  to first end  2   a  by, e.g. press-fitting, for covering end  2   a , cap  4  sometimes encounters deformation in appearance, or burrs are sometimes produced at the end of the opening of housing  7 . When lead-wire  1  is inserted into through-hole  8   a  of sealing member  8 , the deformation or the burr may incur a gap between the outer wall of cap  4  and the inner wall of through-hole  8   a . Burrs produced on lead-wire  1  scratch the inner wall of through-hole  8   a , so that the electrolyte tends to leak. The sealing reliability may be thus lowered. On top of that, the insertion of lead-wire  1  into through-hole  8   a  causes the burrs produced on lead-wire  1  to come off to capacitor element  6 , and may invite a short. 
         [0007]    Patent Literature 1: Japanese Utility Model Publication No. S63-178318 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention aims to provide an electronic component and a lead-wire to be used in this electronic component. The electronic component and the lead-wire achieve reducing burrs and deformation in appearance of a cap, where the deformation and the burrs are produced when the cap is put over and fit to a first end of a led-out electrode. The electronic component and the lead-wire of the present invention thus improve the air-tightness of the sealing of the component as well as the anti-short properties of the component. The present invention also aims to provide methods for manufacturing the component and the lead-wire. 
         [0009]    The lead-wire of the present invention includes a led-out electrode made of metal, and a cap made of metal harder than the metal forming the led-out electrode. The end of led-out electrode is covered with the cap. The electronic component of the present invention is formed of a functional element and the foregoing lead-wire. The led-out electrode is led out of the functional element. The structure discussed above allows preventing the cap from being deformed in appearance when the cap is put over the end of the led-out electrode. 
         [0010]    The outer diameter of the led-out electrode before it is covered with the cap at a first end is set smaller than the inner diameter of the cap. Then the first end of the led-out electrode is covered with the cap, and then a pressure is applied to the outer bottom of the cap, thereby deforming the first end of the led-out electrode made of the metal softer than the metal of the cap while the cap stays free from being deformed. An outer end-face of the first end of the led-out electrode thus can be press-fitted to an inner face of the cap. Therefore, an inner brim of an opening of the cap does not bite an outer brim of the first end of the led-out electrode when putting the cap on the end of the led-out electrode. As a result, burrs produced on the brim of the opening of the cap can be reduced. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1  is a sectional view of an aluminum electrolytic capacitor, which is an example of an electronic component in accordance with a first embodiment of the present invention. 
           [0012]      FIG. 2  is an exploded perspective view which is partially cut, illustrating a part of a capacitor element of the aluminum electrolytic capacitor shown in  FIG. 1 . 
           [0013]      FIG. 3A  is a sectional view of one of manufacturing steps of a lead-wire to be used in the aluminum electrolytic capacitor shown in  FIG. 1 . 
           [0014]      FIG. 3B  is a sectional view of a step following the step shown in  FIG. 3A  for manufacturing the lead wire. 
           [0015]      FIG. 3C  is a sectional view of a step following the step shown in  FIG. 3B  for manufacturing the lead wire. 
           [0016]      FIG. 3D  is a sectional view of a step following the step shown in  FIG. 3C  for manufacturing the lead wire. 
           [0017]      FIG. 3E  is a sectional view of a step following the step shown in  FIG. 3D  for manufacturing the lead wire. 
           [0018]      FIG. 4A  is a sectional view of a step to be done prior to the step shown in  FIG. 3A  for manufacturing the lead wire. 
           [0019]      FIG. 4B  is a sectional view of a step following the step shown in  FIG. 4A  for manufacturing the lead wire. 
           [0020]      FIG. 5  is a sectional view of an aluminum electrolytic capacitor, which is an example of an electronic component in accordance with a second embodiment of the present invention. 
           [0021]      FIG. 6  is an exploded perspective view which is partially cut, illustrating a part of a capacitor element of the aluminum electrolytic capacitor shown in  FIG. 5 . 
           [0022]      FIG. 7A  is a sectional view of one of manufacturing steps of a lead-wire to be used in the aluminum electrolytic capacitor shown in  FIG. 5 . 
           [0023]      FIG. 7B  is a sectional view of a step following the step shown in  FIG. 7A  for manufacturing the lead wire. 
           [0024]      FIG. 7C  is a sectional view of a step following the step shown in  FIG. 7B  for manufacturing the lead wire. 
           [0025]      FIG. 7D  is a sectional view of a step following the step shown in  FIG. 7C  for manufacturing the lead wire. 
           [0026]      FIG. 7E  is a sectional view of a step following the step shown in  FIG. 7D  for manufacturing the lead wire. 
           [0027]      FIG. 7F  is a sectional view of a step following the step shown in  FIG. 7E  for manufacturing the lead wire. 
           [0028]      FIG. 7G  is a sectional view of a step following the step shown in  FIG. 7F  for manufacturing the lead wire. 
           [0029]      FIG. 8A  is a sectional view of one of other manufacturing steps of the lead-wire to be used in the aluminum electrolytic capacitor shown in  FIG. 5 . 
           [0030]      FIG. 8B  is a sectional view of a step following the step shown in  FIG. 8A  for manufacturing the lead wire. 
           [0031]      FIG. 9  is a sectional view of a film capacitor, which is an example of an electronic component in accordance with a third embodiment of the present invention. 
           [0032]      FIG. 10  is an exploded perspective view of a capacitor element of the film capacitor shown in  FIG. 9 . 
           [0033]      FIG. 11A  is a sectional view of one of manufacturing steps of a lead-wire to be used in the film capacitor shown in  FIG. 9 . 
           [0034]      FIG. 11B  is a sectional view of a step following the step shown in  FIG. 11A  for manufacturing the lead wire. 
           [0035]      FIG. 11C  is a sectional view of a step following the step shown in  FIG. 11B  for manufacturing the lead wire. 
           [0036]      FIG. 11D  is a sectional view of a step following the step shown in  FIG. 11C  for manufacturing the lead wire. 
           [0037]      FIG. 11E  is a sectional view of a step following the step shown in  FIG. 11D  for manufacturing the lead wire. 
           [0038]      FIG. 11F  is a sectional view of a step following the step shown in  FIG. 11E  for manufacturing the lead wire. 
           [0039]      FIG. 11G  is a sectional view of a step following the step shown in  FIG. 11F  for manufacturing the lead wire. 
           [0040]      FIG. 12  is a sectional view of an aluminum electrolytic capacitor, which is an example of an electronic component in accordance with a fourth embodiment of the present invention. 
           [0041]      FIG. 13  is an exploded perspective view which is partially cut, illustrating a part of a capacitor element of the aluminum electrolytic capacitor shown in  FIG. 12 . 
           [0042]      FIG. 14  is a sectional view of an aluminum electrolytic capacitor, which is an example of an electronic component in accordance with a fifth embodiment of the present invention. 
           [0043]      FIG. 15  is an exploded perspective view which is partially cut, illustrating a part of a capacitor element of the aluminum electrolytic capacitor shown in  FIG. 14 . 
           [0044]      FIG. 16A  is a sectional view of one of manufacturing steps of a lead-wire to be used in the aluminum electrolytic capacitor shown in  FIG. 14 . 
           [0045]      FIG. 16B  is a sectional view of a step following the step shown in  FIG. 16A  for manufacturing the lead wire. 
           [0046]      FIG. 16C  is a sectional view of a step following the step shown in  FIG. 16B  for manufacturing the lead wire. 
           [0047]      FIG. 16D  is a sectional view of a step following the step shown in  FIG. 16C  for manufacturing the lead wire. 
           [0048]      FIG. 16E  is a sectional view of a step following the step shown in  FIG. 16D  for manufacturing the lead wire. 
           [0049]      FIG. 16F  is a sectional view of a step following the step shown in  FIG. 16E  for manufacturing the lead wire. 
           [0050]      FIG. 17  is a sectional view of a conventional aluminum electrolytic capacitor. 
           [0051]      FIG. 18  is a perspective view of a lead-wire to be used in the aluminum electrolytic capacitor shown in  FIG. 17 . 
           [0052]      FIG. 19  is a sectional view of the lead-wire shown in  FIG. 18 . 
       
    
    
     REFERENCE MARKS IN THE DRAWINGS 
       [0000]    
       
         
           
               11 ,  31 ,  51 ,  61 ,  71 ,  81  lead-wire 
               12 ,  52 ,  62  led-out electrode 
               12   a ,  22   a ,  32   a ,  42   a ,  52   a ,  62   a  first end 
               12   b  second end 
               12   c ,  32   c ,  52   c ,  62   c  first end 
               12   d ,  32   d ,  52   d ,  62   d  metal diffused layer 
               12   e ,  52   e ,  62   e  flat section 
               13   a  chucking jig 
               13   b  welding electrode 
               13   c  welding electrode 
               14 ,  34 ,  84  cap 
               15 ,  75 ,  85  terminal 
               16 ,  56  capacitor element 
               16   a  anode foil 
               16   b  cathode foil 
               16   c  separator 
               17  housing 
               17   a  drawn section 
               18  sealing member 
               18   a  through-hole 
               19 ,  79  insulating terminal board 
               19   a  through-hole 
               19   b  groove 
               20  circuit board 
               22   f ,  32   f ,  52   f ,  62   f , chamfered section 
               24   a ,  34   a ,  84   a  chamfered section 
               32   g ,  52   g ,  62   g  chamfered section 
               33   d  cutter 
               56   a ,  56   b  non-deposited section 
               56   c ,  56   d  deposited electrode 
               56   e ,  56   f  fuse 
               56   g ,  56   h  collector 
           
         
       
     
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0085]    Exemplary embodiments of the present invention are demonstrated hereinafter with reference to the accompanying drawings. Structural elements similar to those used in preceding embodiments have the same reference signs, and the descriptions thereof may be omitted. Only the structural elements different from those used in the preceding embodiments are described. 
       First Embodiment 
       [0086]      FIG. 1  is a sectional view of an aluminum electrolytic capacitor, which is an example of an electronic component in accordance with the first embodiment of the present invention.  FIG. 2  is an exploded perspective view which is partially cut, illustrating a part of a capacitor element of the aluminum electrolytic capacitor shown in  FIG. 1 .  FIGS. 3A-3E  are sectional views of a lead-wire placed in respective manufacturing steps for processing the lead-wire to be used in the aluminum electrolytic capacitor. 
         [0087]    First, the structures of the aluminum electrolytic capacitor and the lead-wire to be used in this capacitor are described with reference to  FIGS. 1 and 2 . As shown in  FIG. 1 , this capacitor is formed of capacitor element  16  working as a functional element, housing  17 , sealing member  18 , and electrically insulating terminal board  19 . Capacitor element  16  is connected with a pair of lead-wires  11 , and housing  17  shaped like a cylinder having a bottom accommodates capacitor element  16 . Sealing member  18  is provided with through-holes  18   a  through which lead-wires  11  extend, and seals the opening of housing  17 . Insulating terminal board  19  is provided with through-hole  19   a , and grooves  19   b  are provided on the outer surface of board  19 . Terminals  15  of lead-wires  11  led out of sealing member  18  are routed through the hole  19   a , and bent approx. at right angles for being accommodated in grooves  19   b . Insulating terminal board  19  is placed such that it closely touches the opening of housing  17 . 
         [0088]    Each one of lead-wires  11  is formed of cylindrical led-out electrode  12  made of metal, cap  14  made of metal, and wire-like terminal  15 . Cap  14  is made of material harder than that of led-out electrode  12 . First end  12   c  of electrode  12  is covered with cap  14 . Terminal  15  is welded onto the outer surface of cap  14 . The outer surface of first end  12   c  is press-fitted to the inner wall of cap  14 , and metal diffused layer  12   d  is formed on at least parts of the interface between cap  14  and first end  12   c , thereby bonding cap  14  and first end  12   c  together. A second end of led-out electrode  12  coupled to capacitor element  16  is processed into flat, thereby forming flat section  12   e.    
         [0089]    Cap  14  is made of material harder than that of led-out electrode  12 . That means cap  14  has greater strength against deformation than first end  12   c . In a case where led-out electrode  12  is made of aluminum round bar, the material of cap  14  can be selected from the metals harder than aluminum, such as iron, nickel, iron-nickel alloys. Other than the foregoing base materials of cap  14 , factors related to the strength, such as a thickness of respective parts of cap  14 , are preferably taken into consideration. 
         [0090]    The inner wall of cap  14  can be plated in order to obtain stronger adhesion to first end  12   c . It can be plated with, e.g. tin, nickel, or copper. In a case where led-out electrode  12  is made of aluminum round bar and cap  14  is made of iron, for example, it is preferable to provide the iron surface with a primary layer of copper, and a plated layer of tin or nickel. It is preferable to provide at least on the inner wall of cap  14  with the foregoing plated layer. 
         [0091]    Terminal  15  is formed of a plate or a wire made of iron, nickel, copper, iron-alloy, nickel-alloy, or copper-alloy: Terminal  15  can be plated on the surface with tin or tin-alloy which contains silver, bismuth, indium, or lead to be ready for connecting with circuit board  20 . 
         [0092]    As shown in  FIG. 2 , led-out electrode  12  is bonded to anode foil  16   a  or cathode foil  16   b  at flat section  12   e  by an ultrasonic welding method or a pressure welding method. Anode foil  16   a  and cathode foil  16   b  are made of valve action metal such as aluminum. Capacitor element  16 , working as a functional element, is formed by rolling up anode foil  16   a  and cathode foil  16   b  together with separator  16   c  placed therebetween. The functional element in this context generally refers to one of active elements and passive elements responsible for electrical functions. For instance, the capacitor element is the one for the capacitor, a battery element or an electrode-group is the one for the battery, and a semiconductor element is the one for the semiconductor. 
         [0093]    Housing  17  is made of metal such as aluminum or aluminum-alloy, and accommodates capacitor element  16  together with electrolytic solution and/or solid electrolyte (not shown) of conductive polymer. Housing  17  is sealed at the opening with elastic sealing member  18  provided on the inner wall of the opening. To be more specific, elastic sealing member  18  receives a stress produced at drawn section  17   a  provided on a part of outer wall of housing  17 . 
         [0094]    Through-hole  18   a  formed in sealing member  18  receives terminals  15  of lead-wires  11 , cap  14 , and led-out electrodes  12  running through hole  18   a  in this order. Terminals  15  are led out of sealing member  18  while led-out electrodes  12  are brought into contact with the inner walls of through-holes  18   a . A diameter of hole  18   a  is set equal to or a little bit smaller than the outer diameter of led-out electrode  12 . Sealing member  18  receives the stress produced at drawn section  17   a  and is pressed, thereby air-tightly sealing the led-out electrodes  12  and the sealing member  18  together. 
         [0095]    Insulating terminal board  19  is brought into contact with the opening of housing  17 , and terminal  15  extends through hole  19   a  provided to board  19  and then bent at approx. right angles. The end of terminal  15  is accommodated in groove  19   b  formed on the surface of board  19 . Insulating terminal board  19  is made of thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate and liquid crystal polymer, or thermosetting resin such as phenol resin and epoxy resin. 
         [0096]    A part of terminal  15  accommodated in groove  19   b  can be processed into a flat shape by pressing so that solder fillet can be readily formed on terminal  15  when terminal  15  is soldered to circuit board  20 . 
         [0097]    Next, a method of manufacturing the lead-wire  11  is demonstrated hereinafter with reference to  FIGS. 3A-3E . First as shown in  FIG. 3A , led-out electrode  12  is held with chucking jig  13   a  at the outer wall such that first end  12   a  of electrode  12  is exposed before first end  12   a  is deformed. Then first end  12   a  is covered with cap  14  (step A). Led-out electrode  12  is formed of cylindrical wire rod, and cap  14  is made by pressing a metal sheet made of material harder than that of led-out electrode  12  so that cap  14  has an opening. The inner diameter of the opening of cap  14  is set greater than the outer diameter of first end  12   a , so that the outer wall of first end  12   a  is not yet press-fitted to the inner wall of cap  14  at this stage, and there is a gap between the outer wall and the inner wall. 
         [0098]    Next, as shown in  FIG. 3B , first end  12   a  is deformed within cap  14 , thereby forming first end  12   c  deformed. Then the inner wall of cap  14  is press-fitted to the outer wall of first end  12   c  (step B). To be more specific, step B is carried out in the following way; first, the inner bottom of cap  14  is brought into contact with the top of first end  12   a , then a pressure is mechanically applied onto the outer bottom of cap  14 . This pressure greatly deforms the outer shape of first end  12   a  while cap  14  stays as it is because first end  12   a  is made of the material softer than that of cap  14 . As a result, deformed first end  12   c  can be formed, and the outer face of first end  12   c  is press-fitted to the inner face of cap  14 . 
         [0099]    Since first end  12   a  is deformed into first end  12   c  by a press and is press-fitted to cap  14 , the outer diameter of the main body of led-out electrode  12  gets different from the outer diameter of first end  12   c.    
         [0100]    The mechanical press onto the outer bottom face of cap  14  can be done, for example, in the following ways; pressing a pin touching the outer bottom of cap  14 , or giving an instantaneous impact to the outer bottom with a hammer or the like. It is preferable to provide the outer bottom with a flat section in order to carry out the foregoing methods. 
         [0101]    It is also preferable to provide a guide contacting the periphery of cap  14  along the direction cap  14  is pressed in order to carry out the foregoing methods. The guide allows readily aligning the center axis of cap  14  with the center axis of led-out electrode  12  when the outer bottom face of cap  14  is mechanically pressed. 
         [0102]    Then, as shown in  FIG. 3C , welding electrodes  13   b  are connected to the outer bottom of cap  14  and led-out electrode  12 , respectively, and cap  14  and electrode  12  is heated by an electrical welding method such as an arc welding method and a resistance welding method (step C). Instead of the foregoing methods, a gas burner, laser, or electromagnetic induction can be used for heating the outer face of cap  14 . The foregoing heat application allows cap  14  and led-out electrode  12  to be melted at an interface formed therebetween by pressure-welding. Metal diffused layer  12   d , which contains the metals forming cap  14  and electrode  12 , is formed on at least parts of this interface. 
         [0103]    Next, as shown in  FIG. 3D , terminal  15  is connected to the outer face of cap  14  (step D). To be more specific, wire-like terminal  15  is pressed onto the outer face of cap  14 , and then welding electrodes  13   c  are connected to terminal  15  and the main body of led-out electrode  12 , respectively. Then, terminal  15  is bonded to cap  14  with the resistance welding method or the like by using welding electrodes  13   c . Terminal  15  can be shaped like a plate instead of a wire-like shape. 
         [0104]    Then, as shown in  FIG. 3E , second end  12   b , which is not covered with cap  14 , is deformed to form flat section  12   e  (step E). When capacitor element  16  is connected to led-out electrode  12 , flat section  12   e  is connected to anode foil  16   a  or cathode foil  16   b  as shown in  FIG. 2  by crimping or ultrasonic welding. Step E can be carried out in the following way; second end  12   b  is pinched at the outer side face and pressed so as to be a flat shape axially parallel with cylindrical led-out electrode  12 , and then cut the peripheries of the flat shape to form flat section  12   e  having a predetermined width and length. Second end  12   b  is not necessarily deformed into the flat shape, but it can be deformed or processed into a shape appropriate to an electrode of the functional element. Lead-wire  11  can be thus manufactured through steps A-E discussed above. 
         [0105]    Next, a method for manufacturing an aluminum electrolytic capacitor, which is an example of the electronic component using lead-wire  11  discussed above, in accordance with the present embodiment is demonstrated hereinafter. 
         [0106]    First, anode foil  16   a , cathode foil  16   b  and separator  16   c  are cut into shapes having predetermined widths and lengths as shown in  FIG. 2 . Anode foil  16   a  has a dielectric layer made of oxide film on the surface. Next, a pair of lead-wires  11  manufactured through steps A-E are connected to anode foil  16   a  and cathode foil  16   b  at flat section  12   e  by crimping or ultrasonic welding, respectively, then separator  16   c  is interposed between anode foil  16   a  and cathode foil  16   b  and they are wound together into a cylindrical shape. The periphery of the cylindrical shape is applied with an insulating adhesive tape or the like (not shown) so that the cylindrical shape can be fixed. Capacitor element  16  can be thus formed. 
         [0107]    The electrode of the functional element can be a sintered body or formed by layering multiple foils instead of winding anode foil  16   a  and cathode foil  16   b  together. 
         [0108]    Next, as shown in  FIG. 1 , capacitor element  16  is accommodated in housing  17  together with the electrolytic solution containing electrolyte. Then, a pair of lead-wires  11  led out of capacitor element  16  is inserted into a pair of through-holes  18   a  formed in sealing member  18 , respectively. In this state, sealing member  18  is placed at the opening of housing  17 . The electrolytic solution can be replaced with solid electrolyte such as conductive polymer, e.g. polypyrrole or polythiophene, or it can be used together with the solid electrolyte. 
         [0109]    Then housing  17  is drawn from the periphery at the outer wall to form drawn section  17   a , thereby sealing the opening of housing  17 . Next, insulating terminal board  19  is placed such that it touches the opening of housing  17 . Terminals  15  of the pair of lead-wires  11  led out of the outer face of sealing member  18  are inserted into a pair of through-holes  19   a  formed in board  19 . 
         [0110]    After that, terminals  15  extending from through-holes  19   a  are bent at right angles in the counter directions to each other, and terminals  15  are put into groove  19   b  formed on the outer surface of insulating terminal board  19 . The surface-mounted type aluminum electrolytic capacitor is thus manufactured. 
         [0111]    When there is a need to make the end of terminal  15  accommodated in groove  19   b  flat, terminal  15  should be pressed into a flat shape by pressing or the like before terminal  15  is run into through-hole  19   a.    
         [0112]    In the case of using solid electrolyte in capacitor element  16 , such as conductive polymer, insulating resin such as epoxy resin can be used as an exterior material instead of using housing  17  and sealing member  18 . In this case, capacitor element  16  is covered with the exterior resin, and terminals  15  of lead-wires  11  are led out of the exterior resin. 
         [0113]    After sealing the opening of housing  17 , or after mounting insulating terminal board  19 , a voltage may be applied across terminals  15  appropriately for re-anodizing the capacitor element. 
         [0114]    As discussed above, lead-wire  11  in accordance with the present embodiment and the method for manufacturing lead-wire  11  prove that cap  14  is made of material harder than that of led-out electrode  12 , so that the appearance of cap  14  is prevented from being deformed when cap  14  is put over first end  12   a.    
         [0115]    The outer diameter of first end  12   a , which is not yet covered with cap  14 , is smaller than the inner diameter of cap  14 . When cap  14  is put over first end  12   a  and is pressed at the outer bottom face, first end  12   a  is deformed by this press into first end  12   c  while cap  14  stays free from deformation. As a result, the outer face of first end  12   c  can be press-fitted to the inner face of cap  14 . Therefore, the inner brim of the opening of cap  14  is prevented from biting the outer brim of first end  12   a  when cap  14  is put over first end  12   a . As a result, burrs to be formed on the end of opening of cap  14  by the foregoing bite can be reduced. 
         [0116]    Lead-wire  11  thus invites fewer amounts of burrs, so that when lead-wire  11  is inserted into through-hole  18   a , it can be prevented that such burrs attach to capacitor element  16 . As a result, a short circuit due to the burrs can be prevented. It is also prevented that sealing member  18  is scratched in through-hole  18   a  by such burrs. The air-tightness of the sealing can be thus increased, and the reliability of the electronic component can be improved. 
         [0117]    First end  12   a  of electrode  12  led out of lead-wire  11  is bonded to cap  14  by mechanical press-fitting, and metal diffused layer  12   d  is formed by melting on the interface between first end  12   c  and cap  14 . This structure increases the bonding strength, so that the bonding reliability is increased. The electronic component using lead-wire  11  thus incurs a smaller number of open-failures caused by a break in lead-wire  11  even if severe vibrations are loaded on the component. 
         [0118]    The melting point of the base material of cap  14  is preferably higher than that of led-out electrode  12 . For instance, in a case where electrode  12  made of aluminum is used, cap  14  is preferably made of metal having a melting point higher than that of aluminum. This structure allows preventing cap  14  from excessively melting during the heat application in step C, thereby preventing malformation such as burrs or projections on the outer face of cap  14  from being produced. 
         [0119]    In a case where led-out electrode  12  is made of aluminum, the base material of cap  14  is preferably selected from copper, nickel, iron, or an alloy containing copper, nickel, or iron. These metals can produce an alloy in liquid phase status at the temperature not higher than the melting point of aluminum. This structure allows forming metal diffused layer  12   d  with ease on the interface formed between first end  12   c  of led-out electrode  12  made of aluminum round bar and cap  14  during the heat application after press-fitted, so that the bonding strength can be increased. It is preferable that the metal having a melting point higher than that of aluminum is provided inside cap  14  in order to encourage the formation of metal diffused layer  12   d . Such a metal can be used as the base material or the plated-layer of cap  14 . 
         [0120]    The electronic component using lead-wire  11  thus incurs a smaller number of open-failures caused by a break in lead-wire  11  even if severe vibrations are loaded on the component. The foregoing structure also allows preventing a short circuit or degradation in air-tightness of the sealing although these failures are caused by burrs or projections formed on the outer face of cap  14 . 
         [0121]    When cap  14  and led-out electrode  12  are bonded together by heating the interface formed by press-fitting, it is preferable to take the thickness and material of cap  14  as well as the covered range of led-out electrode  12  into consideration. Adjustments of these factors allow reducing the malformation caused by over-melting cap  14  while the bonding strength can be increased. The outer bottom and the outer wall of cap  14  to which heat is to be applied preferably have a uniform thickness in order to uniformly melt the interface where cap  14  is press-fitted with first end  12   c.    
         [0122]    In a case where cap  14  is plated with tin on the surface and led-out electrode  12  is made of aluminum round bar, aluminum and tin are diffused in metal diffused layer  12   d . When this diffused state is left in an environment where a heat cycle or a condition of high temperature and high humidity is loaded on the diffused state, the diffused state generally tends to produce tin-whisker. If the diffusing section of aluminum and tin is exposed from the outer face of the electronic component, growth of the tin-whisker sometimes incurs a short circuit. However, in lead-wire  11 , metal diffused layer  12   d  is housed in cap  14 , so that metal diffused layer  12   d  is not exposed outside. Even if metal diffused layer  12   d  contains aluminum and tin, the tin-whisker does not grow outside. As a result, the electronic component using lead-wire  11  can prevent a short circuit caused by the tin-whisker from occurring. In a case where a combination of metals other than aluminum and tin exists in metal diffused layer  12   d , and if the combination of the metals tends to produce whisker, the same advantage as discussed above is obtainable. 
         [0123]    The outer diameter of cap  14  is greater than that of led-out electrode  12  in lead-wire  11 , so that lead-wire  11  has a step (not shown). The presence of the step allows lead-wire  11  extending through hole  18   a  of sealing member  18  to be engaged with sealing member  18  more strongly. As a result, lead-wire  11  can be prevented from shifting toward inside of housing  17 , so that load on the joint between lead-wire  11  and capacitor element  16  can be avoided. Therefore, the electronic component using lead-wire  11  can avoid a break in the wire, a short circuit, and increment in leakage current caused by an abnormality at the junction between lead-wire  11  and capacitor element  16 . 
         [0124]    The diameter of through-hole  18   a  formed on sealing member  18  is preferably set somewhat greater in advance only at the place, where cap  14  provided to lead-wire  11  is to be located, than the other parts of hole  18   a . This preparation allows narrowing the gap between lead-wire  11  and through-hole  18   a , so that the air-tightness of the sealing can be improved, where the gap is produced by the difference in outer diameters between cap  14  and led-out electrode  12 . 
         [0125]    It is preferable that cap  14  has a flaring curve on the entire or parts of its outer wall, and the curve flares from the outer bottom face toward the opening of cap  14 . Cap  14  preferably has the foregoing curve at least on its outer wall that touches the inner wall of through-hole  18   a  when lead-wire  11  is inserted into through-hole  18   a . For instance, the curve may be a domed shape, corned shape or a shape of truncated corn. The presence of the foregoing curve allows reducing load to be applied onto lead-wire  11  during the insertion of lead-wire  11  into through-hole  18   a . Thanks to the curve, lead-wire  11  can be prevented from being deformed, and each one of the pair of lead-wires  11  can be prevented from running differently in timing from each other into through-hole  18   a , so that the junction between lead-wire  11  and capacitor element  16  can be free from load. As a result, the electronic component using lead-wire  11  discussed above can avoid a break in the wire, a short circuit, and increment in leakage current caused by an abnormality at the junction between lead-wire  11  and capacitor element  16 . 
         [0126]    In a case where terminal  15  of lead-wire  11  is made of iron-based material, cap  14  is preferably made of iron, nickel, or iron-nickel based alloy. In a case where terminal  15  is made of copper-based material, cap  14  is preferably made of copper or copper-based alloy. In other words, reducing the difference in electric resistances between terminal  15  and cap  14  prevents malformation such as burrs from occurring when they are resistance-welded together while bonding strength between terminal  15  and cap  14  is maintained. 
         [0127]    When the heat applied during the bonding between the outer face of cap  14  and terminal  15  travels to the interface between cap  14  and first end  12   c , the heat may cause fusion on the interface. At that time, burrs or projections may be produced by this fusion. However, such burrs or projections cannot be exposed outside, because first end  12   c  is covered with cap  14 . The electronic component using lead-wire  11  discussed above thus can avoid a short circuit caused by the burrs to be produced during the insertion of lead-wire  11  into through-hole  18   a , so that the air-tightness of the sealing and the reliability of the electronic component can be improved. 
         [0128]    Terminal  15  is coupled to led-out electrode  12  via cap  14 , so that the materials of terminal  15  and cap  14  can be selected from metals easy-to-weld to each other. For instance, in the case of using laser for bonding terminal  15  to cap  14 , the material for terminal  15  is preferably selected such that it has a melting point or heat conductivity identical or similar to that of cap  14 . This preparation allows stabilizing the bonding strength and preventing malformation caused by over-melting one of cap  14  and terminal  15  at the junction. The electronic component using lead-wire  11  thus can prevent terminal  15  from running off. The electronic component can also prevent a short circuit or a leakage of electrolytic solution caused by malformation such as burrs or projections formed at the junction between cap  14  and terminal  15 . 
         [0129]    Next, manufacturing steps preferably carried out prior to step A demonstrated in  FIG. 3A  are described hereinafter.  FIGS. 4A and 4B  show sectional views of lead-wire  11  in those preceding steps. As shown in  FIG. 4A , it is preferable to add a step of forming flat chamfered section  22   f  on the outer brim of first end  12   a  of led-out electrode  12  (step F) prior to step A. Presence of step F makes the inner brim of the opening of cap  14  harder to touch the outer brim of first end  22   a  when cap  14  is put over first end  12   a , so that the burrs can be further prevented from producing on the end of opening of cap  14 . 
         [0130]    Furthermore, in step A shown in  FIG. 4B , it is preferable to form chamfered section  24   a  at the inner brim of the opening of cap  14 . The presence of chambered section  24   a  allows the inner brim of the opening of cap  14  to make further harder to touch the outer brim of first end  22   a  of led-out electrode  12 . As a result, the production of the burrs can be further reduced. The shape of chamfered sections  22   f  and  24   a  can be a curve, which produces an advantage similar to what a flat chamfered section produces. 
         [0131]    As described above, in the electronic component using lead-wire  11 , a short circuit caused by the burrs is prevented from occurring when lead-wire  11  is inserted into through-hole  18   a , and the air-tightness of the sealing and the reliability of the electronic component are improved. 
       Second Embodiment 
       [0132]      FIG. 5  is a sectional view of an aluminum electrolytic capacitor, which is an example of an electronic component in accordance with the second embodiment of the present invention.  FIG. 6  is an exploded perspective view which is partially cut, illustrating a part of a capacitor element which works as a functional element of the aluminum electrolytic capacitor shown in  FIG. 5 .  FIGS. 7A-7G  show sectional views of the lead-wire, placed in respective manufacturing steps, to be used in the aluminum electrolytic capacitor shown in  FIG. 5 . First, the structures of the aluminum electrolytic capacitor and its lead-wire are described with reference to  FIGS. 5 and 6 . 
         [0133]    In  FIG. 5 , the aluminum electrolytic capacitor differs from the one shown in  FIG. 1  in the shape of first end  32   c  having undergone the deformation, of led-out electrode  12  of lead-wire  31 . To be more specific, first end  32   c  is narrower than the main body of led-out electrode  12  and the difference in the outer diameters between cap  34  put over first end  32   c  and the main body of led-out electrode  12  is smaller than that of the aluminum electrolytic capacitor shown in  FIG. 1 . 
         [0134]    A method for manufacturing lead-wire  31  discussed above in accordance with the second embodiment is demonstrated with reference to  FIGS. 7A-7G . This method differs from the one shown in  FIGS. 3A-3E  in the presence of a step prior to step A shown in  FIG. 7C , namely, in this preceding step (step G), first end  32   a  (before the deformation) of led-out electrode  12  is narrowed as shown in  FIG. 7A . In step G, first end  32   a  is pressed with a tooling die into a shape narrower than the main body of led-out electrode  12 , for example. 
         [0135]    In step A following step G, cap  34  is put over first end  32   a . In step B shown in  FIG. 7D  following step A, the outer bottom face of cap  34  is pressed mechanically until deformed first end  32   c  is brought into contact with and press-fitted to the inner face of cap  34 . The dimensions to be processed of first end  32   a  are thus set such that the opening end of cap  34  does not touch the step, which is formed due to the difference in the outer diameters between the main body of electrode  12  and first end  32   a , during the application of a press in step B. 
         [0136]    Meanwhile, flat chamfered section  32   f  is preferably formed on the outer brim of first end  32   a  (step F) as shown in  FIG. 7B  in parallel with or just after step G. Flat chamfered section  32   g  is preferably formed on the outer brim of the step produced due to the difference in the outer diameters between the main body of led-out electrode  12  and first end  32   a  (step H). 
         [0137]      FIGS. 7E-7G  illustrate the steps similar to steps C, D and E described in the first embodiment and demonstrated in  FIGS. 3C-3E , so that the descriptions of the steps shown in  FIGS. 7E-7G  are omitted here. Lead-wire  31  can be thus manufactured through the steps G, F, H, A, B, C, D and E. The method for manufacturing the aluminum electrolytic capacitor using lead-wire  31  is similar to the method demonstrated in the first embodiment. 
         [0138]    As discussed above, first end  32   a  of led-out electrode  12  of lead-wire  31  in accordance with the present embodiment is processed to be narrower than the main body of electrode  12 . This structure allows reducing the difference in the outer diameters between cap  34  which is put over end  32   a  and press-fitted to led-out electrode  12 , and the main body of led-out electrode  12 . As a result, a short circuit caused by the burrs to be produced when lead-wire  31  is inserted into through-hole  18   a  of sealing member  18 , can be prevented from occurring. In the case that the thickness of sealing member  18  is thin, a gap between through-hole  18   a  and lead-wire  31  can be prevented from occurring. The air-tightness of the sealing can be thus improved. 
         [0139]    Use of lead-wire  31  thus manufactured through the steps discussed above including step H allows an edge of outer rim of the step produced due to the difference in the outer diameters between the main body of led-out electrode  12  and first end  32   a , not to form in an acute angle. Therefore, sealing member  18  can be prevented from being scratched at the inside of through-hole  18   a  when lead-wire  31  is inserted into through-hole  18   a . As a result, the electrolytic solution can be prevented from leaking, and the air-tightness of the sealing can be improved. Step H can be carried out in parallel with or just after step G, or at the same time as or before or after step F. 
         [0140]    As shown in  FIG. 7C , chamfered section  34   a  is preferably formed on the inner brim of the opening of cap  34 . This structure makes the inner brim of the opening of cap  34  further harder to touch the outer brim of first end  32   a , and the burrs can be prevented from being formed on the end of the opening of cap  34 . 
         [0141]    Chamfered sections  32   f ,  32   g , and  34   a  shown in  FIGS. 7B and 7C  can have curved shapes in stead of flat shapes. The curved chamfered sections can produce an advantage similar to what the flat chamfered section produces. 
         [0142]    Next, another step G is described with reference to  FIGS. 8A and 8B , which show sectional views of lead-wire  31  placed in other manufacturing steps. 
         [0143]    In step G shown in  FIG. 8A , undeformed first end  42   a  of led-out electrode  12  is processed into a shape of truncated corn, i.e. a trapezoid in sectional view. To be more specific, an outer diameter of the tip of first end  42   a  is processed into a smaller one. This tip shaped like the truncated corn makes the inner rim of the opening of cap  34  further harder to touch the outer brim of first end  42   a  when cap  34  is put over first end  42   a  so as to prevent the burrs from being formed on the end of the opening of cap  34  more effectively. 
         [0144]    The advantages of the present embodiment are described by using specific instances. First, the aluminum round bar having 1.3 mm diameter and 99.99% purity is used as the material for the main body of led-out electrode  12 . 
         [0145]    Cap  34  is formed by pressing an iron sheet, and the dimensions of its opening are set as followings: the outer diameter is 1.6 mm, the inner diameter is 1.3 mm, and the length is 0.8-1.0 mm. The bottom of cap  34  is curved at the outer rim and has a flat circular section having a diameter ranging from 0.3 mm to 1.0 mm. The surface of cap  34  includes a nickel-plated layer containing copper as a primary coat, and the nickel-plated layer has a thickness ranging from 2 μm to 10 μm. Flat chamfered section  34   a  is provided to an inner brim of the end of opening of cap  34 . 
         [0146]    Terminal  15  is made of iron-wire of which outer diameter is 0.6 mm, and a nickel-plated layer, containing copper as a primary coat and having a thickness ranging from 2 μm to 10 μm, is formed on the surface of terminal  15 . 
         [0147]    In step G shown in  FIG. 7A , first end  32   a  of led-out electrode  12  is pressed with the tooling die so that end  32   a  can be shaped narrower than the main body of electrode  12  and the inner diameter of cap  34 , namely, the outer diameter of end  32   a  is processed to be 1.10 mm. The length of end  32   a  along the axial direction of electrode  12  is processed to be 1.3 mm which is longer than the length of cap  34 . 
         [0148]    Step F shown in  FIG. 7B  is carried out simultaneously with step G: flat chamfered section  32   f  is formed on the outer brim of first end  32   a  with a tooling die. On top of that, in step H, flat chamfered section  32   g  is formed on the outer brim of the step produced due to the difference in the outer diameters between the main body of led-out electrode  12  and first end  32   a.    
         [0149]    Next, in step A shown in  FIG. 7C , the main body of electrode  12  is held by chucking jig  13   a  at the outer surface such that first end  32   a  is exposed, and then end  32   a  is covered with cap  34  so that the inner bottom of cap  34  touches the end face of first end  32   a.    
         [0150]    Then in step B shown in  FIG. 7D , the outer bottom of cap  34  is mechanically pressed until first end  32   a  is deformed inside cap  34  to have a greater outer diameter and the outer face of deformed first end  32   c  of lead-wire  12  is brought into contact with the inner face of cap  34  and press-fitted together. 
         [0151]    Next, in step C shown in  FIG. 7E , welding electrodes  13   b  are connected respectively to the outer bottom of cap  34  and the main body of led-out electrode  12 , and then cap  34  and first end  32   c  are heated by the resistance-welding method. At that time, the temperature rises around the melting point of the metals used as materials for cap  34  and electrode  12 , so that the interface formed by press-fitting between cap  34  and electrode  12  is melted. Metal diffused layer  32   d  containing the metals used as the materials for cap  34  and electrode  12  is thus formed in the interface. 
         [0152]    Then in step D shown in  FIG. 7 , wire-shaped terminal  15  is urged against the outer face of cap  34 , and welding electrodes  13   c  are coupled to terminal  15  as well as the main body of electrode  12  respectively, whereby terminal  15  is bonded to electrode  12  with the resistance-welding method. 
         [0153]    Next, in step E shown in  FIG. 7G , second end  12   b  of led-out electrode  12  is pressed at the outer side face so that second end  12   b  is shaped into a plate in parallel with an axial direction of electrode  12 , then this plate is trimmed at the periphery into flat section  12   e . Lead-wire  31  is thus manufactured through steps G, F, H, A, B, C, D, and E. 
         [0154]    A comparative sample lead-wire is produced in order to compare foregoing lead-wire  31  and an aluminum electrolytic capacitor using lead-wire  31  with this comparative sample lead-wire and another capacitor using the comparative sample lead-wire. The comparative sample lead-wire is produced in the following way: it is formed of led-out electrode  12 , cap  34 , and terminal  15  same as those of lead-wire  31 . In step G shown in  FIG. 7A , when first end  32   a  of electrode  12  is narrowed, its outer diameter is set at 1.4 mm slightly greater than the inner diameter of cap  34 . This structure requires a mechanical press onto the outer bottom face of cap  34  when cap  34  is put over first end  32   a  so that the inner bottom face of cap  34  touches the end face of first end  32   a . As a result, the cylindrical face of first end  32   a  is press-fitted to the inner face of cap  34  in step A, so that step B can be omitted. The other steps are carried out in the same way as lead-wire  31  is manufactured. The comparative sample lead-wire is produced through steps G, F, H, A, C, D, and E. 
         [0155]    The aluminum electrolytic capacitor using lead-wire  31  and another aluminum electrolytic capacitor using this comparative sample lead-wire are produced. The process of the production of the capacitor using lead-wire  31  is demonstrated hereinafter as an example with reference to  FIGS. 5 and 6 . First, an aluminum foil is processed with an etching process, and then the foil is processed with chemical oxidation in aqueous solution of ammonium borate, thereby forming an oxide film on the aluminum foil. Anode foil  16   a  is thus produced. On the other hand, an aluminum foil is processed with an etching process, thereby forming cathode foil  16   b.    
         [0156]    Second, flat sections  12   e  of lead-wires  31  are press-fitted to anode foil  16   a  or cathode foil  16   b , respectively. Then, separator  16   c  made of manila-paper is placed between anode foil  16   a  and cathode foil  16   b , and these members are wound up to form capacitor element  16 . 
         [0157]    Next, capacitor element  16  is impregnate with electrolytic solution, and then accommodate element  16  into housing  17  made of aluminum and shaped like a cylinder having a bottom. After that, sealing member  18  chiefly made of butyl rubber is mounted to the opening of housing  17  while a pair of lead-wires  31  led out of capacitor element  16  is run into through-holes  18   a  formed in sealing member  18 . As a result, terminals  15  are led outside sealing member  18 . 
         [0158]    Next, housing  17  and sealing member  18  is together processed with a drawing process at the outer wall of housing  17  for sealing the end of the opening of housing  17 . Then insulating terminal board  19  is brought into contact with the opening of housing  17 , and terminals  15  exposed outside sealing member  18  are inserted into through-holes  19   a  formed in board  19 . Finally, terminals  15  are bent at approx. right angles and accommodated into groove  19   b  formed on the surface of board  19 . A surface-mounted type aluminum electrolytic capacitor rated at 6.3V and 1500 μF is thus produced through the steps discussed above. 
         [0159]    One thousand pieces of lead-wire  31  and the comparative sample lead-wire are manufactured, respectively. Then, appearance defects caused by burrs produced on the end of opening of cap  34  joined to led-out electrode  12  are investigated, and defects in a test of tensile strength between electrode  12  and cap  34  are investigated for the pieces. 
         [0160]    The investigation of appearance defects results in no defects of lead-wires  31 , however, 200 appearance defects are found in the comparative sample lead-wires. The investigation of tensile strength results in no defects both in lead-wires  31  and the comparative sample lead-wires. The results prove that lead-wire  31  can maintain the bonding strength between electrode  12  and cap  34  while it can reduce the burrs produced on the end of opening of cap  34  comparing with the comparative sample lead-wire. 
         [0161]    One thousand pieces of the aluminum electrolytic capacitor using lead-wire  31  and another aluminum electrolytic capacitor using the comparative sample lead-wire are manufactured, respectively, and then defects caused by shorts in a reflow test are investigated. 
         [0162]    The investigation results in no defects in the capacitors which use lead-wires  31 , however, five defects are found in the other capacitors which use the comparative sample lead-wires. The investigation proves that use of lead-wire  31  allows preventing defects caused by a short circuit after the reflow, and the reliability of the aluminum electrolytic capacitor can be improved. 
       Third Embodiment 
       [0163]      FIG. 9  is a sectional view of a film capacitor, which is an example of an electronic component in accordance with the third embodiment of the present invention.  FIG. 10  is an exploded perspective view of a capacitor element which works as a functional element of the film capacitor.  FIG. 11A-FIG .  11 G are sectional views of lead-wires, placed in respective manufacturing steps, to be used in the film capacitor. First, the structures of the film capacitor and the lead-wire to be used in the film capacitor are described with reference to  FIGS. 9 and 10 . 
         [0164]    The film capacitor shown in  FIG. 9  differs from the aluminum electrolytic capacitor shown in  FIG. 5  of the second embodiment in the following points: Capacitor element  56  formed of metalized film is used as a functional element, and respective flat sections  52   e  and  62   e  of lead-wires  51  and  61  are bent and their tips are connected respectively to collectors  56   g  and  56   h  formed on the end-faces of capacitor element  56 . 
         [0165]    As shown in  FIG. 9 , the film capacitor has capacitor element  56 , housing  17 , sealing member  18 , and insulating terminal board  19 . Capacitor element  56  is formed by winding up a pair of metalized films into a cylindrical shape, and includes collectors  56   g ,  56   h  at both of the end-faces. Lead-wires  51 ,  61  are connected to collectors  56   g  and  56   h , respectively. To be more specific, flat sections  52   e  and  62   e  of lead wires  51  and  61  are bent, and the tips of the flat sections are bonded to collectors  56   g  and  56   h , respectively. Led-out electrodes  52  and  62  are led out in pairs to a first end-face side of capacitor element  56 . 
         [0166]    Cylindrical housing  17  having a bottom is made of aluminum or aluminum alloy and accommodates capacitor element  56  therein. A space is provided between the outer surface of capacitor element  56  and the inner surface of housing  17  in order to avoid a touch between them. 
         [0167]    Sealing member  18  seals an opening of housing  17  and is provided with a pair of through-holes  18   a  through which lead-wires  51  and  61  are inserted. Insulating terminal board  19  is placed such that it touches the opening of housing  17 , and is provided with through-hole  19   a  through which a pair of terminals  15  led outside from through-holes  18   a  are inserted. Terminal board  19  is provided with grooves  19   b  at its outer surface for accommodating terminals  19  run through hole  19   a  and bent at approx. right angles. Terminals  15  accommodated in grooves  19   b  are connected to circuit board  20 . 
         [0168]    As shown in  FIG. 10 , a pair of metalized films forming capacitor element  56  respectively include a dielectric film, deposited electrode  56   c ,  56   d  formed by depositing a metal such as aluminum on the surface of the dielectric film, and fuse  56   e ,  56   f . Non-deposited sections  56   a ,  56   b  are respectively formed on an end of each dielectric film in the width direction. The dielectric film is formed of one of polyethylene-terephthalate, polypropylene, polyethylene-naphthalate, or polyphenylene-sulfide and the like. Fuses  56   e ,  56   f  have self-preservation function such as the deposited sections are blown out and electrically cut when an abnormal current runs. The pair of metalized films discussed above is wound up into a cylindrical shape such that deposited electrodes  56   c  and  56   d  do not touch each other, whereby capacitor element  56  is formed. As shown in  FIG. 9 , a pair of collectors  56   g  and  56   h  are formed on end faces of capacitor element  56 , respectively, and connected to deposited electrodes  56   c  and  56   d , respectively. 
         [0169]    A pair of metalized film can be layered to form a laminated capacitor element instead of the structure discussed above. 
         [0170]    A method for manufacturing lead-wires  51 ,  61  is demonstrated hereinafter with reference to  FIGS. 11A-11G . 
         [0171]    The manufacturing method shown in  FIGS. 11A-11G  differs from the method shown in  FIGS. 7A-7G  of the second embodiment in the following point: both of the ends of a single piece of led-out electrode  12  are processed and then cut to form a pair of lead-wires  51  and  61 . To be more specific, in steps G, F, H shown in  FIG. 11A , both of the ends of led-out electrode  12  are processed to form first ends  52   a  and  62   a , not deformed yet but having a shape narrower than the main body of electrode  12 . Then, chamfered sections  52   g ,  52   f ,  62   g  and  62   f  are formed by processing each one of the tips and the steps. After that, in step A shown in  FIG. 11B , caps  34  is put over first ends  52  and  62   a , respectively, and then in step B shown in  FIG. 11C , caps  34  are pressed against led-out electrode  12  to form first ends  52   c  and  62   c , so that caps  34  are press-fitted to electrode  12 . Furthermore, in step C shown in  FIG. 11D , metal diffused layers  52   d  and  62   d  are formed, and in step D shown in  FIG. 11E , each terminal  15  is connect to each cap  34 . 
         [0172]    After step D shown in  FIG. 11E , namely, in step I shown in  FIG. 11F , led-out electrode  12  is cut vertically with respect to the axial direction into two parts. In step I, led-out electrode  12  is cut with cutter  33   d  at approx. the center. In a case where flat sections  52   e  and  62   e  of lead-wires  51  and  61  differ in length from each other as shown in  FIG. 9 , the cutting point can be adjusted according to the ratio of the lengths. Finally in step E shown in  FIG. 11G , flat sections  52   e  and  62   e  are formed. Lead-wires  51  and  61  are thus manufactured through steps G, F, H, A, B, C, D, I and E discussed above. 
         [0173]    Step I can be carried out after step B or step C. Step E can be carried out before step I. 
         [0174]    A manufacturing method for a film capacitor using lead-wires  51  and  61 , as an example of the electronic components in accordance with the present embodiment is demonstrated hereinafter. 
         [0175]    The method differs from the one shown in  FIG. 9  of the second embodiment in the following points: capacitor element  56  is produced in a different way, and the film capacitor needs no electrolyte such as an electrolytic solution. The other steps remain the same as those described in the second embodiment. 
         [0176]    First, a method for manufacturing capacitor element  56  is demonstrated. As shown in  FIG. 10 , deposited electrodes  56   c  and  56   d  are formed respectively on each first face of a pair of dielectric films of which widths are cut to a given width while non-deposited sections  56   a  and  56   b  are left on each end of the films along the longitudinal direction. 
         [0177]    Then the films are laminated with each other such that deposited electrodes  56   c  and  56   d  do not touch each other and non-deposited sections  56   a  and  56   b  confront each other. The metalized films are then wound to make a cylindrical shape to form a rolled unit. Deposited electrodes  56   c  and  56   d  are exposed from the end faces of the rolled unit. 
         [0178]    Next, the melted metal such as aluminum, tin, or copper is sprayed onto both the end faces of the pair of metalized films wound into the cylindrical shape, thereby forming collectors  56   g  and  56   h , which are then connected to deposited electrodes  56   c  and  56   d , respectively. 
         [0179]    Then, flat sections  52   e  and  62   e  of lead-wires  51  and  61  are bent, and the tips of the bent flat sections are connected to collectors  56   g  and  56   h  by spot-welding, respectively. Led-out electrodes  52  and  62  are led out in pairs out of the rolled unit along the same direction, whereby capacitor element  56  is formed. 
         [0180]    Next, capacitor element  56  is accommodated into housing  17 . At this time, a space is provide between element  56  and housing  17 , or housing  17  is provided with an insulating member at the inner surface. One of these preparations prevents the outer surface of element  56  from touching the inner surface of housing  17 . 
         [0181]    Next, the opening of housing  17  is sealed with sealing member  18  with the same method as the one carried out in the second embodiment to be ready for surface mounting. 
         [0182]    As discussed above, capacitor element  56  formed of the metalized films, from which end-faces deposited electrodes  56   c  and  56   d  are exposed, can use lead-wires  51  and  61 . In other words, flat sections  52   e  and  62   e  are bent and connected to element  56 , thereby forming the film capacitor. Use of lead-wires  51  and  61  allows reducing the burrs due to the bites by lead-wires  51  and  61  when they are run into through-holes  18   a  of sealing member  18 , so that a short circuit caused by the burrs can be reduced as same as the second embodiment. The air-tightness of sealing the film capacitor can be also improved. 
         [0183]    The method for manufacturing the lead-wires in accordance with the present embodiment can manufacture two lead-wires  51  and  61  from a single piece of led-out electrode  12  in an efficient manner, so that the productivity is increased. 
       Fourth Embodiment 
       [0184]      FIG. 12  is a sectional view of an aluminum electrolytic capacitor, which is an example of an electronic component in accordance with the fourth embodiment of the present invention.  FIG. 13  shows an exploded perspective view which is partially cut, illustrating a capacitor element working as a functional element of the aluminum electrolytic capacitor. 
         [0185]    First, the structures of the aluminum electrolytic capacitor and the lead-wire to be used in this capacitor are described with reference to  FIGS. 12 and 13 . The capacitor shown in  FIG. 12  differs from the aluminum electrolytic capacitor shown in  FIG. 5  of the second embodiment in lead-wire  71  having no terminal  75  in advance. To be more specific, terminal  75  is insert-molded with electrically-insulating terminal board  79  placed such that board  79  touches and fronts the opening of housing  17 , and terminal  75  is connected to cap  34  of lead-wire  71 . 
         [0186]    This aluminum electrolytic capacitor is formed of capacitor element  16 , housing  17 , sealing member  18 , and insulating terminal board  79 . A pair of lead-wires  71  is connected to capacitor element  16 , and each one of lead-wires  71  includes led-out electrode  12  and cap  34 , which is connected to first end  32   c  of led-out electrode  12 . A second end of led-out electrode  12  is processed into flat section  12   e . A structure of lead-wire  71  is thus similar to the structure of lead-wire  31  in accordance with the second embodiment but it does not have terminal  15 . Insulating terminal board  79  includes a pair of terminals  75  and is placed such that it touches and fronts the opening of housing  17 . The outer bottom of cap  34  of lead-wire  71  is exposed outside of through-hole  18   a  of sealing member  18 . A pair of caps  34  is bonded respectively to the pair of terminals  75  provided to insulating terminal board  79  at the outer bottom. Terminals  75  are connected to circuit board  20 . 
         [0187]    Lead-wire  71  can be manufactured in a similar way to lead-wire  31  in accordance with the second embodiment except that step D shown in  FIG. 7F , in which terminal  15  is connected to lead-wire  31 , is not conducted for lead-wire  71 . 
         [0188]    Next, a method for manufacturing the aluminum electrolytic capacitor using lead-wires  71  is demonstrated hereinafter. First, as shown in  FIG. 13 , anode foil  16   a , cathode foil  16   b , and separator  16   c  are cut into given shapes having given lengths and widths. Flat sections  12   e  of lead-wires  71  are connected to anode foil  16   a  and cathode foil  16   b  by crimping or ultrasonic welding, respectively. Then, separator  16   c  is interposed between anode foil  16   a  and cathode foil  16   b , and these elements are wound together into a cylindrical shape. The cylindrical shape is fixed with an electrically insulating tape (not shown) so that capacitor element  16  is formed. 
         [0189]    Capacitor element  16  working as a functional element can be formed by laminating multiple pairs of anode foil  16   a  and cathode foil  16   b  instead of winding anode foil  16   a  and cathode foil  16   b  together, or can be formed of a sintered body instead of anode foil  16   a  and cathode foil  16   b.    
         [0190]    Next, as shown in  FIG. 12 , capacitor element  16  is accommodated in housing  17  together with the electrolytic solution containing electrolyte. Then, a pair of lead-wires  71  led out of capacitor element  16  are inserted into a pair of through-holes  18   a  formed in sealing member  18 , respectively. In this state, sealing member  18  is placed at the opening of housing  17 . The electrolytic solution can be replaced with solid electrolyte such as conductive polymer, e.g. polypyrrole or polythiophene, or the electrolytic solution can be used together with the solid electrolyte. 
         [0191]    Then, housing  17  is drawn at the outer peripheral wall to form drawn section  17   a , thereby sealing the opening of housing  17 . At this time, the outer surface of cap  34  is exposed from through-hole  18   a  of sealing member  18 . 
         [0192]    Then, insulating terminal board  79  is placed  7  so as to touch the opening of housing  17 . Each of first ends of a pair of terminals  75 , which are provided to board  79  by insert-molding, is brought into contact with each of caps  34  at the outer surface exposed from through-holes  18   a  of sealing member  18 , and they are connected to each other by welding or the like. 
         [0193]    In the case of that capacitor element  16  employs solid electrolyte, such as conductive polymer, an electrically-insulating exterior resin such as epoxy resin can be used instead of using housing  17  and sealing member  18 . In this case, capacitor element  16  is covered with the exterior resin, and the outer surface of cap  34  of each of lead-wires  11  is led out of the exterior resin. 
         [0194]    After sealing the opening of housing  17 , or after mounting the insulating terminal board  79 , a voltage is applied across terminals  75  appropriately for re-anodizing the capacitor element. 
         [0195]    In the structure discussed above, cap  34  put over first end  32   c  is well bonded to terminal  75 , so that there is no need for cap  34  to be bonded in advance to terminal  75 . Terminal  75  can be bonded to the outer surface of cap  34  after lead-wire  71  is run into through-hole  18   a  and the outer surface of cap  34  is exposed outside. This structure thus can prevent the burrs from occurring during the insertion of lead-wire  71  into through-hole  18   a , so that the short circuit caused by the burrs can be reduced as same as in the second embodiment. Additionally, the variation in locations of terminals  75  caused by bending the terminals can be small since terminal  75  is formed in advance on insulating terminal board  79  by insert-molding. As a result, the aluminum electrolytic capacitor can be steadily mounted by soldering. 
       Fifth Embodiment 
       [0196]      FIG. 14  is a sectional view of an aluminum electrolytic capacitor, which is an example of an electronic component in accordance with the fifth embodiment of the present invention.  FIG. 15  is an exploded perspective view which is partially cut, illustrating a capacitor element working as a functional element of the aluminum electrolytic capacitor shown in  FIG. 14 .  FIG. 16A-FIG .  16 F are sectional views of a lead-wire, placed in respective manufacturing steps, to be used in the aluminum electrolytic capacitor. 
         [0197]    First, the structures of the aluminum electrolytic capacitor and the lead-wire to be used in this capacitor are described with reference to  FIGS. 14 and 15 . The capacitor shown in  FIG. 14  differs from the aluminum electrolytic capacitor shown in  FIG. 5  of the second embodiment in using lead-wire  81  instead of lead-wire  31 . Terminal  85  of lead-wire  81  is not welded to the outer surface of cap  84 , but it is formed in one body together with cap  84 . 
         [0198]    Next, a method for manufacturing the lead-wire to be used in the aluminum electrolytic capacitor as an example of the electronic component in accordance with the fifth embodiment is demonstrated hereinafter with reference to  FIGS. 16A-16F . 
         [0199]    The manufacturing steps shown in  FIGS. 16A-16F  differ from the ones shown in  FIGS. 7A-7G  in the following two points: Cap  84  is produced so as to be formed in one body together with terminal  85 , which is formed on the outer surface of cap  84  as shown in  FIG. 16A  (step J), and step J is carried out in parallel with, or before or after steps G, F, and H shown in  FIG. 16B . Step D for connecting cap  84  to terminal  85  by welding is eliminated. 
         [0200]    In step J, a block-shaped base material such as iron is pressed to form terminal  85  on cap  84  so as to form them into one unit. At this time, chamfered section  84   a  is preferably formed on the end of the opening of cap  84 . 
         [0201]    Lead-wire  81  to be used in the aluminum electrolytic capacitor, which is an example of the electronic component in accordance with the fifth embodiment, is produced by using cap  84  through manufacturing steps G, F, H, A, B, C, and E.  FIGS. 16C ,  16 D,  16 E and  16 F show steps A, B, C, and E, respectively. 
         [0202]    In step B shown in  FIG. 16D , first end  12   a  of led-out electrode  12  is deformed to form first end  12   c , and the outer face thereof and the inner face of cap  84  are press-fitted together. At this time, a pressure is mechanically applied onto the outer bottom face of cap  84  such that the pressure is not applied to terminal  85 . 
         [0203]    In step C shown in  FIG. 16E , cap  84  and led-out electrode  12  are heat-treated. During the heat treatment, welding electrode  13   b  is preferably connected to the outer surface of cap  84  except the location of terminal  85 . This preparation allows efficiently forming metal diffused layer  32   d.    
         [0204]    Next, lead-wires  81  instead of lead-wires  31  are used for producing the aluminum electrolytic capacitor in a similar way to the second embodiment. 
         [0205]    As discussed above, since terminal  85  is formed together with cap  84  in one body on the outer surface of cap  84 , the step for welding terminal  85  to cap  84  can be omitted for improving the productivity. Variations in shapes and strength at the junction between terminal  85  and cap  84  are thus extremely small, so that the quality in connection is improved. 
         [0206]    Since the shape at the junction between terminal  85  and cap  84 , which are formed together in one body, is stable, a gap between lead-wire  81  and through-hole  18   a  of sealing member  18  is prevented from occurring. As a result, the air-tightness of the sealing can be improved. On top of that, vibration proof properties of the electronic component can be improved against severe vibration load. The electronic component of high reliability can be thus manufactured. 
       INDUSTRIAL APPLICABILITY 
       [0207]    As described above, according to the electronic component according to the present invention, appearance of the cap can be prevented from being deformed when a cap is put over a first end of a led-out electrode of an electronic component, because the cap is made of a material harder than that of the lead-wire. 
         [0208]    After the cap is put over the first end of the led-out electrode, the cap is pressed at the outer bottom face, so that the end of the led-out electrode is deformed while the cap remains not-deformed. An outer face of the end of the led-out electrode can be thus press-fitted to an inner face of the cap. This structure proves that an inner brim of an end of the opening of the cap can avoid biting an outer brim of the first end of the led-out electrode. In other words, this structure allows reducing burrs to be produced on the end of the opening of the cap. 
         [0209]    As a result, the foregoing structure allows reducing the burrs caused by the deformation in the appearance of the cap or caused by the bites on the first end of the led-out electrode by the end of the opening of the cap, so that degradation caused by the burrs in air-tightness of the sealing can be prevented and a short circuit caused by the burrs can be also prevented. The present invention can be thus applied to a highly reliable electronic component that needs strict air-tightness at the sealing and resistance to short circuits.

Technology Category: 5