Abstract:
To provide a capacitor device that has a fusing feature and which can be made miniaturized, lighter in weight and thin-shaped, comprising a plurality of conductive pattern electrodes  20  and  21  electrically separated by a separation groove  19 ; a capacitor element  15  in which at least either one of an anode lead  16  and a cathode lead  17  is connected via a thin metal wire  22  having a fusing feature to the conductive pattern electrodes  20  and  21 ; and a insulating resin  24  for covering a part except for the capacitor element  15  and a part working as the conductive pattern electrodes and for integrally supporting the conductive pattern electrode and the capacitor element.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a tantalum chip type capacitor device used for a portable device such as a telephone that is allowed to have a fusing feature.  
           [0003]    2. Related Art  
           [0004]    A tantalum chip type capacitor device has been used for a part such as a power source circuit for a portable device requiring a large capacity such as telephones, laptop computers, and miniaturized, lighter weight, and thin-shaped tantalum chip type capacitor devices have been demanded and a fusing feature has also been sought in terms of being used as a power source circuit.  
           [0005]    [0005]FIG. 9 is a cross-sectional view showing a capacitor element of the chip tantalum capacitor.  
           [0006]    As shown in FIG. 9, the capacitor element  1  is made in such a manner that tantalum (Ta)  2  in the form of metal powders and a tantalum bar for drawing out a lead wire are subjected to pressurization, molding and vacuum hardening, and in the surface thereof, a tantalum oxide film (Ta 2 O 5 )  4  used as a dielectric body is formed by electrochemical anodization.  
           [0007]    As an electrolyte, a solid manganese dioxide layer (MnO 2 )  5  is formed on the dielectric body by the thermal decomposition of manganese nitrate. In order to allow this manganese dioxide layer  5  to have thereon an electric connection, the graphite layer  6  is provided. On the graphite layer  6 , a cathode lead  8  is formed by use of a silver covering material  7  and a conductive adhesive agent.  
           [0008]    [0008]FIG. 10 is a schematic view of a conventional chip tantalum capacitor device using the capacitor element  1 . As shown in FIG. 10, the anode terminal  9  which is bent in the shape of an overturned latter  1  is welded to the tantalum bar  3  of the capacitor element  1  provided as described above at a welding point  10 . The cathode terminal  11  bent in a complicated manner is pressure-bonded to the cathode lead E formed of conductive adhesive agent. Furthermore, the capacitor element  1 , the anode terminal  9 , and the cathode terminal  11  are partially exposed to the exterior to be molded by an epoxy resin  12 , thereby forming the chip tantalum capacitor.  
           [0009]    As described above, bent and intricately-shaped electrode elements have been used for an anode lead and a cathode lead of conventional chip tantalum capacitor devices, thus requiring man-hours and cost. Additionally, bent and intricately-shaped electrode elements have been used, therefore, miniaturized, lighter weight and thin-shaped chip capacitors cannot be achieved.  
           [0010]    If the conventional chip tantalum capacitor has a fusing feature, the capacitor cannot be prevented from being larger and thicker because of the inclusion of the fusing feature, which is contrary to the need for a miniaturized, lighter weight and thin-shaped chip capacitor. In this case, additional labor has been required for including the fuse.  
         SUMMARY OF THE INVENTION  
         [0011]    The capacitor device of preferred embodiment of the present invention is miniaturized, thin-shaped and lighter in weight, and the preferred embodiment provides a chip capacitor having a fusing feature. The present invention provides a capacitor device comprising a plurality of conductive pattern electrodes electrically separated by a separation groove; a capacitor element in which at least either one of an anode lead or a cathode lead is connected to the conductive pattern electrode via a thin metal wire having a fusing feature, and an insulating resin for covering a part except for the capacitor element, the thin metal wire, and a part working as the conductive pattern electrode and for integrally supporting the conductive pattern electrode, the thin metal wire, and the capacitor element.  
           [0012]    The preferred embodiment provides a capacitor device comprising a plurality of conductive pattern electrodes electrically separated by a separation groove; a capacitor element in which at least either one of an anode lead or a cathode lead is connected to first and second conductive pattern electrode via a thin metal wire having a fusing feature, respectively, a circuit element bare chip attached to a third conductive pattern electrode; and an insulating resin for covering the capacitor element, parts working as the bare chip, the thin metal wire, and a part except for the first, second and third conductive pattern electrodes and for integrally supporting the first, second and third conductive pattern electrodes, the capacitor element, and the bare chip.  
           [0013]    Accordingly, a complicated metal fitting used for an anode terminal and a cathode terminal as an electrode as in the conventional chip capacitor becomes unnecessary, thereby realizing a miniaturized, lighter weight and thin-shaped capacitor device.  
           [0014]    Further, the capacitor element as well as another circuit element chip forming a hybrid integrated circuit are simultaneously attached to the conductive pattern and are covered and fixed with the insulating resin, thereby forming a hybrid integrated circuit in which the capacitor element is assembled. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a side view showing the capacitor device of the preferred embodiment.  
         [0016]    [0016]FIG. 2 is a side view illustrating a manufacturing process of the capacitor device of the preferred embodiment.  
         [0017]    [0017]FIG. 3 is a side view illustrating a manufacturing process of the capacitor device of the preferred embodiment.  
         [0018]    [0018]FIG. 4 is a side view illustrating another manufacturing process of the capacitor device of the preferred embodiment.  
         [0019]    [0019]FIG. 5 is a side view showing another embodiment of the capacitor device of the preferred embodiment.  
         [0020]    [0020]FIG. 6 is a side view showing another embodiment of the capacitor device of the preferred embodiment.  
         [0021]    [0021]FIG. 7 is a side view showing another embodiment of the capacitor device of the preferred embodiment.  
         [0022]    [0022]FIG. 8 is a side view showing another embodiment of the capacitor device of the preferred embodiment.  
         [0023]    [0023]FIG. 9 is a cross-sectional view showing the capacitor elements used for the capacitor devices of the preferred embodiment and the related art.  
         [0024]    [0024]FIG. 10 is a schematic view showing the conventional chip tantalum capacitor. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    The capacitor device of the preferred embodiment will be described with reference to FIG. 1 to FIG. 8.  
         [0026]    [0026]FIG. 1 is a side view illustrating the capacitor device of the preferred embodiment. The capacitor element  15  has an anode lead  16  that is provided, as described above, by subjecting the tantalum Ta in the form of metal powders and the tantalum bar to pressurization, molding, and vacuum hardening. The capacitor element  15  has also a cathode lead  17  that is provided with a graphite layer and a conductive adhesive agent on the manganese dioxide layer which is made into a dielectric body consisting of a tantalum oxide film.  
         [0027]    The anode lead  16  and the cathode lead  17  of the capacitor element  15  are constructed by a hybrid integrated circuit technique (which will be described later) and is connected to first and second conductive pattern electrodes  20  and  21  separated by the separation groove  19 . The anode lead  16  is connected via the thin metal wire  22  having a fusing feature. The one end of the thin metal wire  22  is subjected to wire-bonding to be connected to the anode lead  16 , while the other end is connected to the first conductive pattern electrode  20 .  
         [0028]    In order to connect the thin metal wire  22  to the anode lead  16 , a flat section (e.g., a bonding pad) is required to be formed so that the thin metal wire  22  can be subjected to a wire bonding to connect to a tantalum bar working as the anode lead  16 . Further, the thin metal wire  22  is plated so as to be subjected to a wire bonding. The thin metal wire  22  also may be welded instead of being subjected to a wire bonding.  
         [0029]    The thin metal wire  22  is composed of aluminum, gold or the like. The capacity of the fusing current is adjusted depending on the number of wires to be bonded.  
         [0030]    The cathode lead  17  is soldered to the second conductive pattern  21  with a solder  23 . The cathode lead  17  is directly soldered and fixed to the second conductive pattern electrode  21  with the solder  23 . Alternatively, the cathode lead  17  also may be fixed by Ag paste or an electrically conductive adhesive agent instead of being soldered.  
         [0031]    The capacitor element  15 , the anode lead  16 , the cathode lead  17 , the thin metal wire  20 , and the first and second conductive pattern electrodes  20  and  21  except for the lower faces are covered with the insulating resin  24  and integrally supported by the insulating resin  24 , thereby forming the chip type capacitor device.  
         [0032]    In the capacitor device, the lower faces of the first and second conductive pattern electrodes  20  and  21  are exposed, thus allowing capacitor device to be directly attached to a printed circuit of a printed substrate to form a power source circuit or the like. If the capacitor element  15  has a short circuit due to some reason, a large current flows in the circuit, and this may cause burnout of the circuit element or the like. However, the capacitor device of the preferred embodiment allows the thin metal wire  22  to be firstly fusion-cut, thereby preventing other circuit elements from being burnt out.  
         [0033]    In the above description, the anode lead  16  of the capacitor element  15  is connected to the first conductive pattern electrode  20  via the thin metal wire  22  having a fusing feature, however, the cathode lead  17  also may be connected to the second conductive pattern electrode  21  via the thin metal wire having a fusing feature.  
         [0034]    [0034]FIG. 2 and FIG. 3 are side views illustrating the process for assembling the capacitor device of FIG. 1 using a special hybrid integrated circuit technique. First, the conductive foil  30  is prepared as shown in FIG. 2A. The conductive foil is mainly composed of Cu but also may be composed mainly of Al or may composed of an alloy such as Fe—Ni or the like.  
         [0035]    Next, as shown in FIG. 2E, photoresists are patterned such that the conductive foil  30  is exposed except for a region working as the conductive patterns  31  and  32  constituting the first and second conductive pattern electrodes  20  and  21  of the conductive foil. Then, as shown in FIG. 2C, the conductive foil  30  is selectively etched to form a plurality of conductive patterns  31  and  32  separated by the separation groove  19 . In this status, a part working, as the first and second conductive pattern electrodes  20  and  21  of the conductive patterns  31  and  32  is separated by the separation groove  19  but the lower part is connected.  
         [0036]    Thereafter, as shown in FIG. 3A, the cathode lead  17  of the capacitor element  15  is soldered and fixed to the conductive pattern  32  with the solder  23 . Then, one end of the thin metal wire  22  is bonded to the bonding pad of the anode lead  16  of the capacitor element  15 . The other end of the thin metal wire  22  is bonded to a wire bonding pad  33  of the conductive pattern  31 , thereby connecting the anode lead  16  of the capacitor element  15  to the conductive pattern  31 . In this case, the conductive patterns  31  and  32  are still connected, thus facilitating the operation.  
         [0037]    Thereafter, as shown in FIG. 3E, the capacitor element  15 , the anode lead  16 , the cathode lead  17 , the thin metal wire  22 , and the conductive patterns  31  and  32  are entirely covered with the insulating resin  34  and these are supported and fixed. Finally, the insulating resin  39  is cut off from the conductive patterns  31  and  32  at a broken line shown in FIG. 3B. This allows as shown in FIG. 3C the conductive pattern  31  to be perfectly separated from the conductive pattern  32  and the lower part of the separated part becomes the externally exposed the first and second conductive pattern electrodes  20  and  21  in which the conductive patterns  31  and  32  are exposed. Specifically, the capacitor device shown in FIG. 1 is completed.  
         [0038]    In FIG. 2 and FIG. 3, only the capacitor device is assembled by a hybrid integrated circuit technique, FIG. 4 is a side view illustrating the process for assembling the capacitor device with other circuit elements.  
         [0039]    In FIG. 4A, as described above, the conductive patterns  31  and  32  are formed in which the parts working as the conductive pattern electrodes are separated at the separation groove  19  and a third conductive pattern  38  is also formed in which a part working as a flip chip pad  38 A is separated by a separation groove  37 .  
         [0040]    Next, as shown in FIG. 4B, the cathode lead  17  of the capacitor element  15  is soldered to the conductive pattern  32  with the solder  23 . The thin metal wire  22  is bonded to the wire bonding pad of the anode lead  16  of the capacitor element  15  and the wire bonding pad  33  of the conductive pattern electrode  31  to connect the anode lead  16  to the conductive pattern electrode  31 .  
         [0041]    Then the flip chip pad  38 A formed in the conductive pattern  38  is attached with a bare chip  39  which is a power transistor as a circuit element, for example. Then, the electrode of the bare chip  39  is bonded and connected to the conductive pattern  32  via a thin metal wire  40 .  
         [0042]    Next, as shown in FIG. 4C, the capacitor element  15 , the anode lead  16 , the cathode lead  17 , the conductive patterns  31 ,  32 , and  38 , the bare chip  39 , and the thin metal wiring  20  and  40  are entirely covered with the insulating resin  24  and these are supported and fixed.  
         [0043]    Thereafter, the insulating resin  24  is cut off from the conductive patterns  31 ,  32 , and  38  at the broken line shown in FIG. 4C. As shown in FIG. 4D, this allows the conductive patterns  31 ,  32 , and  33  to be perfectly separated from one another, and the separated part becomes the externally exposed conductive pattern electrodes  20 ,  21 , and  38 , thereby forming the hybrid integrated circuit in which the capacitor element is assembled.  
         [0044]    Although the power transistor bare chip as an example of the circuit element is given as described above, the circuit element also may be an LSI bare chip and the number of the circuit elements is not limited to one and a plurality of required circuit elements also may be assembled at the same time.  
         [0045]    [0045]FIG. 5 shows another embodiment of the capacitor device of preferred embodiment of the present invention. In FIG. 1, only the anode lead  16  of the capacitor element  15  and the first conductive pattern electrode  20  are connected via the thin metal wire  22  having a fusing feature. However, the capacitor element  15  is fixed to the pad  42  formed together with the conductive pattern electrodes  20  and  21 , and the cathode lead  17  is connected to the second conductive pattern electrode  21  via the thin metal wire  43  having a fusing feature.  
         [0046]    Otherwise, details of the structure are the same as in the above, the capacitor element  15 , the anode lead  16 , the cathode lead  17 , and the first and second conductive pattern electrodes  20  and  21  except for the lower faces are covered with the insulating resin  24  and are integrally supported, thereby forming the chip type capacitor device.  
         [0047]    Similarly, FIG. 6 shows another example of the capacitor device of preferred embodiment of the present invention, however this differs from FIG. 1 in that the anode lead  16  is slid to extrude from the lower part of the dielectric body. This allows the anode lead  16  and the first conductive pattern electrode  20  to approach each other, thereby facilitating a wire bonding of the thin metal wire  22  to the wire bonding pad of the anode lead  16 .  
         [0048]    Similarly, FIG. 7 shows another example of the capacitor device of preferred embodiment of the present invention. The face from which the anode lead  16  of the capacitor element  15  is extruded is plated to be flat. The flat plated layer  44  is wire-bonded to one end of the thin metal wire  22  and the other end of the thin metal wire  22  is wire-bonded to the first conductive pattern electrode  20 , thereby connecting the anode lead  16  to the conductive pattern electrode  44 . Otherwise, details of the structures are the same as in FIG. 5.  
         [0049]    As shown in FIG. 7, FIG. 8 shows a capacitor device using the capacitor element  15  with the face from which the anode lead  16  is extruded is flat by use of the plated layer  44 . The capacitor element  15  is directed downward in the longitudinal direction of the cathode lead  17 . Then, the cathode lead  17  is soldered to the second conductive pattern electrode  21  with the solder  23 .  
         [0050]    The plated layer  44  positioned at the upper face of the capacitor element  15  is wire-bonded with one end of the thin metal wire  22 , while the other end of the thin metal wire  22  is wire-bonded with the first conductive pattern electrode  20 , thereby connecting the anode lead  16  to the conductive pattern electrode  44 .  
         [0051]    As shown in FIG. 4, the methods of FIG. 5 to FIG. 8 also can be applied to a case where the capacitor device as well as other circuit element bare chips are simultaneously covered and supported with an insulating resin. Additionally, it is the same that the capacity of the fusing current is adjusted depending on the number of the thin metal wire  22  or the thin metal wires  43 .  
         [0052]    As shown in FIG. 4, the methods of FIG. 5 to FIG. 8 also can be applied to a case where the capacitor device as well as other circuit element bare chips are simultaneously covered and supported with an insulating resin. Additionally, it is the same that the capacity of the fusing current is adjusted depending on the number of the thin metal wire  22  or the thin metal wires  43 .