Conductive cap, electronic component, and method of forming insulating film of conductive cap

Abstract

A conductive cap for use in an electronic component, has an opening at a bottom portion thereof, and is constructed to be fixed to the upper surface of a substrate of the electronic component at the opening portion of the cap so as to cover at least an electronic component element mounted on the upper surface of the substrate having terminal electrodes provided thereon. The end surface of the opening and the inner and outer surfaces thereof in connection to and in the vicinity of the end surface are provided with an insulating film disposed thereon.

What is claimed is:  
     
         1 . A conductive cap for use in an electronic component, the conductive cap comprising: 
 an upper surface, a lower surface and inner and outer side surfaces;    an opening on the lower surface thereof, the cap being adapted to be fixed to the upper surface of the substrate of the electronic component on the opening side of the cap so as to cover at least an electronic component element mounted on the upper surface of the substrate having terminal electrodes disposed thereon; wherein    an end surface of said opening and the inner and outer side surfaces thereof in connection to and in the vicinity of the end surface are provided with an insulating film formed thereon.    
     
     
         2 . A conductive cap according to  claim 1 , wherein the insulation resistance between the opening end surface of the conductive cap and the outer side of the insulation film is at about least 10 9 Ω.  
     
     
         3 . A conductive cap according to  claim 1 , wherein the thickness of said insulating film is in the range of about 4 μm to about 25 μm.  
     
     
         4 . A conductive cap according to  claim 1 , wherein when the opening end surface of the conductive cap and an adjacent portion thereof are viewed in a section taken substantially perpendicularly relative to the circumferential direction of the conductive cap, the opening end surface of the cap and the inner side surface thereof in connection to the opening end surface define a curved line, and the radius R of curvature of the curved line is in the range of about 80 μm to about 150 μm.  
     
     
         5 . An electronic component comprising: 
 a substrate having a plurality of terminal electrodes disposed on at least an upper surface thereof;    an electronic component element fixed to the substrate and electrically connected to the plurality of terminal electrodes; and    a conductive cap having an opening on a lower surface thereof and an insulating film provided on the opening end surface thereof and an adjacent portion, and bonded to the substrate on the opening side thereof.    
     
     
         6 . An electronic component according to  claim 5 , wherein said electronic component element is a piezoelectric element.  
     
     
         7 . An electronic component according to  claim 5 , wherein the conductive cap is a metallic cap.  
     
     
         8 . A method of forming an insulating film of a conductive cap, the method comprising the steps of: 
 holding a plurality of conductive caps each having an opening on a lower surface thereof while the conductive caps are arranged by a holding device;    pressing the opening end surface side of the plurality of conductive caps held by the holding device against a resin layer for forming an insulating film having a predetermined thickness, and thereafter separating the conductive caps from the resin layer for forming an insulating film, whereby the insulating film is formed on the opening end surface of each conductive cap and the vicinity of the opening end surface by a transfer method; and    drying the insulating film after the transfer step.    
     
     
         9 . A method of forming an insulating film of a conductive cap according to  claim 8 , wherein the resin used for forming an insulating film is a resin having a viscosity at about 25±5° C. of about 5000 cps to about 20000 cps.  
     
     
         10 . A method of forming an insulating film of a conductive cap for sealing an electronic component, the method comprising the steps of: 
 providing a conductive cap being adapted to be fixed to the surface of a substrate having terminal electrodes formed thereon so as to cover and seal an element mounted to the surface of the substrate;    forming an insulating film on the conductive cap so that the insulating film electrically insulates the terminal electrodes from the conductive cap; wherein    the conductive cap is made of one of aluminum and an aluminum alloy, and the insulating film is formed on the surface of the conductive cap by anodization carried out in the cap-shaped state.    
     
     
         11 . A method of forming an insulating film of a conductive cap according to  claim 10 , wherein the anodization is carried out while the conductive cap is held by a jig and is electrically connected.  
     
     
         12 . A method of forming an insulating film of a conductive cap according to  claim 10 , wherein after a sheet material is punched to form caps, the anodization is carried out while the caps are partially connected to the sheet material and kept in a hoop state.  
     
     
         13 . A method of forming an insulating film of a conductive cap according to  claim 12 , wherein the hoop is fed into the anodization bath, and after the anodization, the hoop is wound, whereby the anodization is continuously carried out.  
     
     
         14 . A method of forming an insulating film of a conductive cap according to  claim 12 , wherein the hoop is cut to a predetermined unit length and is dipped into an anodization bath to be anodization-treated.  
     
     
         15 . A conductive cap for sealing an electronic component, the conductive cap comprising: 
 a cap body including a lower surface which is adapted to be fixed to a surface of a substrate of the electronic component so as to cover and seal an element mounted onto the surface of the substrate having terminal electrodes disposed thereon, the conductive cap body is made of one of aluminum and an aluminum alloy; and    an insulating film is disposed at least on the surface portions of the conductive cap to be contacted with the terminal electrodes.    
     
     
         16 . A method of forming an insulating film of a conductive cap for sealing an electronic component, the method comprising the steps of: 
 providing a conductive cap adapted to be fixed to the surface of the substrate of the electronic component having terminal electrodes disposed thereon so as to cover and seal an element mounted onto the surface of the substrate;    forming an insulating film on the conductive cap so that the insulating film electrically insulates the terminal electrodes from the conductive cap; wherein    the insulating film is formed on the surface of the conductive cap by electrodeposition coating.    
     
     
         17 . A method of forming an insulating film of a conductive cap according to  claim 16 , further comprising the steps of bonding a conductive double side adhesion tape to a conductive supporting sheet, and bonding the conductive cap to the conductive double side adhesion tape, so that the conductive cap is electrically connected, supported, and electrodeposition-coated.  
     
     
         18 . A method of forming an insulating film of a conductive cap according to  claim 16 , wherein the electrodeposition coating is carried out while the conductive cap is supported by a jig and electrically connected.  
     
     
         19 . A conductive cap for sealing an electronic component, comprising: 
 a conductive cap body that is adapted to be fixed to a surface of a substrate of the electronic component having terminal electrodes disposed thereon so as to cover and seal an element mounted onto the surface of the substrate; and    an insulating film disposed at least on the portions of the conductive cap to be contacted with the terminal electrodes.    
     
     
         20 . A conductive cap for covering and sealing an element mounted onto the surface of a substrate having terminal electrodes formed thereon, wherein said conductive cap has an insulating film disposed at least on the surface of the portions of the cap that are arranged to contact the terminal electrodes.