JP2005191194A - Ceramic container and tantalum electrolytic capacitor employing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic container for tantalum electrolytic capacitor exhibiting excellent mass productivity in which airtightness of a tantalum electrolytic capacitor element can be sustained even if it is exposed to high temperature in soldering and the size can be reduced, and to provide a tantalum electrolytic capacitor. <P>SOLUTION: The ceramic container 6 comprises a ceramic substrate 3 having a recess 3-B provided with a first metallize layer 3a and a second metallize layer 3b formed independently on the inner surface and a first conductor layer 3c and a second conductor layer 3d formed independently on the lower surface, a first connection conductor 3e formed on the inner surface of a first trench 30 formed vertically in the side face of the ceramic substrate 3, and a second connection conductor 3f formed on the inner surface of a second trench 31 formed vertically in the side face of the ceramic substrate 3 wherein the first trench 30 and the second trench 31 have upper and lower end parts beveled in the shape of curved surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a tantalum electrolytic capacitor used for an electronic circuit or the like, and more particularly to a tantalum electrolytic capacitor configured using a ceramic container.

  A surface mount type tantalum electrolytic capacitor is known as a conventional resin-encapsulated solid electrolyte capacitor. These tantalum electrolytic capacitors are used in large quantities in a wide range of fields including communication equipment such as mobile phones, AV equipment such as digital cameras, computer equipment such as personal computers, and automobile equipment such as airbags and anti-lock brakes. Applications include power supply smoothing circuits, computer backups, timer circuits that use the charge / discharge time of tantalum electrolytic capacitors, and high-frequency filters, which are indispensable electronic components for the above equipment.

  Such a tantalum electrolytic capacitor is composed of a tantalum electrolytic capacitor element portion, a lead frame, and an exterior resin that hermetically seals the lead frame, and the lead frame generally has a strength such as an iron (Fe) -nickel (Ni) alloy. The one with high is used. As the exterior resin, an epoxy resin or the like is used because of its good heat resistance and moisture resistance.

  A conventional tantalum electrolytic capacitor of this type will be described below with reference to FIG. FIG. 5 is a cross-sectional view showing the structure of a conventional tantalum electrolytic capacitor, in which 11 is a tantalum electrolytic capacitor, 12 is a tantalum electrolytic capacitor element, 12b is an anode lead, and the tantalum electrolytic capacitor element 12 is made of tantalum or the like. One end portion of the anode lead 12b is embedded, and a sintered body 12a obtained by sintering a compact made of tantalum powder embedded so that the other end portion protrudes from the side surface is sintered on a dielectric oxide film layer ( (Not shown), a solid electrolyte layer (not shown) is formed outside the oxide film layer, and then a cathode layer 12c is formed on the outer periphery.

  The other end of the anode lead 12b is welded to the lead frame 13, and the lead frame 13 protrudes from the exterior resin 14 and is bent along the outer shape of the exterior resin 14 to reach the lower surface. Is done. Further, the lead frame 13 is bonded onto the cathode layer 12c via the conductive bonding material 15, and protrudes from the outer resin 14 and is bent along the outer shape of the outer resin 14 to reach the lower surface of the outer resin 14. The cathode terminal 13b for connection is used. The lead frame 13 has a structure derived in both directions from the same height of the opposing side surfaces of the exterior resin 14 so as to be a connecting terminal for both electrodes and to bend.

  Next, a method for manufacturing the tantalum electrolytic capacitor 11 will be described. First, the tantalum electrolytic capacitor element 12 is mounted on the fixing portion 16 of the tantalum electrolytic capacitor element 12 of the lead frame 13, and the cathode layer 12c and the cathode terminal 13b of the tantalum electrolytic capacitor element 12 are connected to the thermosetting conductive bonding material 15. Join through. Further, the anode lead 12b and the anode terminal 13a of the tantalum electrolytic capacitor element 12 are joined to each other by welding. Also. As the conductive bonding material 15, for example, an epoxy resin bonding material containing silver (Ag) is used, and is cured by heating at a temperature of about 300 ° C. for about 10 minutes.

Further, the tantalum electrolytic capacitor element 12 bonded to the lead frame 13 is placed at a predetermined position, and then the end portions of the anode terminal 13a and the cathode terminal 13b, which are bonded to the external electric circuit board, are exposed to the outside. The tantalum electrolytic capacitor element 12 is covered with an epoxy-based exterior resin 14 together with a part of the lead frame 13, and the exterior resin 14 is cured by heating at 150 to 180 ° C. for about 1 hour. As a result, the polymer crosslinking ratio of the exterior resin 14 is increased, the heat resistance and the moisture resistance are improved, and the highly reliable tantalum electrolytic capacitor 11 is obtained. Next, the lead frame 13 is bent downward along the outer shape of the exterior resin 14 so that the anode terminal 13a and the cathode terminal 13b are located on the lower surface of the tantalum electrolytic capacitor 11, thereby constituting a part of the lower surface of the tantalum electrolytic capacitor 11. To do. This facilitates mounting on an external electric circuit board and can be suitable for mass production.
JP 2002-134360 A (page 3-4, FIG. 1)

  However, in recent years, Pb-free solder that does not use lead (Pb) has come to be used as awareness of global environmental problems increases. Pb-free solder has a soldering temperature that is 40-50 ° C higher than the conventional soldering temperature (220-230 ° C) of tin (Sn) 60% -Pb 40%. If this is done, the exterior resin 14 will be altered by heat and a gap will be formed between it and the lead frame 13. Moisture will enter through this gap, causing leakage current, or causing a failure due to a short circuit. Had problems.

Therefore, it has been studied to add a filler such as silica (SiO ₂ ) or alumina (Al ₂ O ₃ ) to the exterior resin 14 to impart high heat resistance. In this case, the thermal expansion coefficient of the exterior resin 14 is considered. And the difference in thermal expansion coefficient from the lead frame 13 increases. As a result, a gap is generated between the lead frame 13 and the exterior resin 14 at the temperature of the soldering process, and moisture or the like enters to cause the above-described defect. Therefore, this method is not practical.

Furthermore, the use of a highly heat-resistant resin such as polyimide as the exterior resin 14 has also been studied. In addition to the expensive material, polyimide has a coefficient of thermal expansion that is the coefficient of thermal expansion of the lead frame 13 (7 × 10 ^{− 6} / ° C.), which is about 60 × 10 ⁻⁶ / ° C., which is more than 8 times the value, and a gap is generated between the lead frame 13 and the exterior resin 14 to cause the above-mentioned defect. Had.

  Further, since the conventional tantalum electrolytic capacitor 11 has a structure in which the lead frame 13 protrudes from the exterior resin 14, it has become impossible to meet the recent demand for downsizing of the tantalum electrolytic capacitor 11.

  Therefore, the present invention has been completed in view of the above problems, and its purpose is to maintain the airtightness of the tantalum electrolytic capacitor element even when the tantalum electrolytic capacitor is exposed to a high temperature such as during soldering. Another object of the present invention is to provide a tantalum electrolytic capacitor that can be miniaturized and has excellent mechanical reliability, electrical characteristics, and mass productivity.

  In the ceramic container of the present invention, a rectangular parallelepiped recess is formed at the center of the upper surface, the first metallized layer and the second metallized layer are formed independently on the inner surface of the recess, and the first is formed on the lower surface. A conductive layer and a second conductive layer formed independently of each other, and an inner surface of a first groove formed in a vertical direction on a side surface of the ceramic base, the first metallized layer, A first connecting conductor for electrically connecting the first conductor layer; and an inner surface of a second groove formed in a vertical direction on a side surface of the ceramic base; the second metallized layer and the A second connecting conductor that electrically connects the second conductor layer, and the first groove and the second groove are chamfered in a curved shape at the upper end and the lower end. It has a chamfered part

  In the ceramic container of the present invention, preferably, the thickness of the first connection conductor located in the chamfered portion of the first groove is such that the portion other than the chamfered portion of the first connection conductor and the first metallization. The thickness of the second connection conductor located in the chamfered portion of the second groove is thicker than each thickness of the layer and the first conductor layer, and the portion other than the chamfered portion of the second connection conductor and It is characterized by being thicker than each thickness of the second metallized layer and the second conductor layer.

  In the ceramic container of the present invention, preferably, the first connection conductor is wider than the first metallization layer, and the second connection conductor is wider than the second metallization layer. And

  According to the tantalum electrolytic capacitor of the present invention, an anode lead in which one end is embedded in the side surface of the ceramic container of the present invention and the sintered body of tantalum powder and the other end is welded to the first metallized layer. A tantalum electrolytic capacitor element having a terminal and a cathode layer deposited on the lower surface of the sintered body and electrically connected to the second metallization layer; And a lid attached in this manner.

  According to the ceramic container of the present invention, the rectangular parallelepiped recess is formed at the center of the upper surface, the first metallized layer and the second metallized layer are formed independently from each other on the inner surface of the recess, and the first Formed on the inner surface of the first groove formed in the vertical direction on the side surface of the ceramic substrate, the first metallized layer and the second conductor layer formed on the side surface of the ceramic substrate; A first connection conductor that electrically connects one conductor layer; and a second metallized layer and a second conductor layer formed on an inner surface of a second groove formed in a vertical direction on a side surface of the ceramic substrate. And a second connection conductor for electrically connecting the first conductor layer and the second conductor layer to the wiring conductor of the external electric circuit board using Pb-free solder. Even when connected, the ceramic substrate is heat resistant. To reason, since no ceramic substrate gap is generated in the ceramic container is deformed by heat can be favorably maintained airtight. Therefore, it is possible to effectively prevent moisture from entering the inside of the ceramic container, and to effectively prevent leakage current and occurrence of defects due to short circuit.

  Therefore, the airtightness of the tantalum electrolytic capacitor element is significantly higher than that of the conventional structure having the exterior resin and the lead frame. It is possible to effectively prevent the operation, and to maintain the electrical characteristics of the tantalum electrolytic capacitor element well over a long period of time.

  In addition, after forming the first groove and the second groove, the first connection conductor is formed on the inner surface of the first groove and the second connection conductor is formed on the inner surface of the first groove. The connecting conductor and the second connecting conductor can be accurately formed at desired positions, and the productivity can be improved, and the ceramic container can be manufactured efficiently.

  Furthermore, since the connection area between the connection conductor and the ceramic base can be increased by forming the connection conductor on the inner surface of the groove as compared with the case where the connection conductor is formed on the flat side surface of the ceramic base, The bonding strength of the connecting conductor can be improved and the electrical resistance of the connecting conductor can be reduced.

  According to the ceramic container of the present invention, the first groove and the second groove formed in the vertical direction on the side surface of the ceramic substrate have chamfered portions in which the upper end portion and the lower end portion are chamfered in a curved shape. Therefore, compared with the case where the upper and lower ends of the groove are not chamfered in a curved shape, that is, the upper and lower ends of the groove have corners, the conductive distance of the metallized layer, the wiring conductor and the conductor layer is shortened. In addition, since there is no corner portion where the electric resistance tends to be high when a current flows, the electric resistance can be reduced, and the device can always be favorably operated with a desired performance.

  In addition, by reducing the electrical resistance of the connection conductor, a large current can flow through the connection conductor. When the anode lead terminal of the tantalum electrolytic capacitor element is welded to the first metallization layer by the welding method, the first metallization is performed. It is possible to increase the electrical resistance only at the contact portion between the layer and the anode lead terminal to increase the temperature. Therefore, the anode lead terminal can be welded and joined to the first metallized layer efficiently and reliably.

  Further, a groove is formed on the side surface of the ceramic substrate in the vertical direction and a connection conductor is formed on the inner surface thereof, and the lower end of the groove is chamfered in a curved shape. When using and surface-mounting to the electrode of the external electric circuit board, the bonding area between the connecting conductor and the electrode of the external electric circuit board can be increased, and a good meniscus can be formed. Is high and the electrical resistance is low.

  According to the ceramic container of the present invention, preferably, the thickness of the connection conductor located at the chamfered portion of the groove is thicker than the thickness of the portion other than the chamfered portion of the connection conductor, the metallized layer, and the conductor layer. The electrical resistance can be further reduced at the upper and lower ends of the groove that tends to increase. That is, the electric resistance of the conductive path formed by the metallized layer, the connecting conductor, and the conductor layer can be made smaller, and the tantalum electrolytic capacitor can always be operated well with a desired performance, and the anode lead terminal Can be efficiently and reliably welded together by the first metallized layer.

  According to the ceramic container of the present invention, preferably, the first connection conductor is wider than the first metallization layer, and the second connection conductor is wider than the second metallization layer. The electrical resistance of the second connecting conductor can be smaller than that of the first and second metallized layers. As a result, the tantalum electrolytic capacitor can always be satisfactorily operated with desired performance, and the anode lead terminal can be efficiently and reliably welded to the first metallized layer.

  According to the tantalum electrolytic capacitor of the present invention, the anode lead terminal in which one end is embedded in the side surface of the ceramic container of the present invention and the sintered body of tantalum powder and the other end is welded to the first metallized layer. And a tantalum electrolytic capacitor element having a cathode layer deposited on the lower surface of the sintered body and electrically connected to the second metallized layer, and attached to the upper surface of the ceramic base so as to close the recess. Since it has a lid, it has high hermeticity and high mechanical and electrical reliability, and can be improved in productivity and downsizing and welded between the anode lead terminal and the metallized layer. Bonding can be performed efficiently and reliably.

  The ceramic container and tantalum electrolytic capacitor of the present invention will be described in detail below. Fig.1 (a) is a top view which shows an example of embodiment of the ceramic container of this invention, FIG.1 (b) is sectional drawing of the ceramic container of Fig.1 (a). FIG. 4 is a cross-sectional view showing an example of an embodiment of the tantalum electrolytic capacitor of the present invention. In these drawings, 1 is a tantalum electrolytic capacitor, 2 is a tantalum electrolytic capacitor element, 3 is a ceramic substrate, 3a is a first metallized layer, 3b is a second metallized layer, 3c is a first conductor layer, and 3d is a first metallized layer. The second conductor layer, 3e is the first connection conductor, 3f is the second connection conductor, 30 is the first groove, 31 is the second groove, 4 is the lid, and 6 is the ceramic container.

  In the ceramic container 6 of the present invention, a rectangular parallelepiped concave portion 3-B is formed at the center of the upper surface, and the first metallized layer 3a and the second metallized layer 3b are formed independently of each other on the inner surface of the concave portion 3-B. In addition, the ceramic substrate 3 having the first conductor layer 3c and the second conductor layer 3d formed independently on the lower surface, and the first groove 30 formed on the side surface of the ceramic substrate 3 in the vertical direction. A first connection conductor 3e which is formed on the inner surface and electrically connects the first metallized layer 3a and the first conductor layer 3c, and a second groove 31 which is formed on the side surface of the ceramic substrate 3 in the vertical direction. And a second connection conductor 3f that electrically connects the second metallized layer 3b and the second conductor layer 3d, and includes a first groove 30 and a second groove 31. Is a chamfer where the upper and lower ends are chamfered in a curved shape. Part 30a, has 30b, 31a, and 31b.

  In the ceramic container 6, the anode lead terminal 2b of the tantalum electrolytic capacitor element 2 is welded to the first metallized layer 3a, and the cathode layer 2c of the tantalum electrolytic capacitor element 2 is electrically connected to the second metallized layer 3b. The lid 4 is attached to the upper surface of the side wall 3-A of the ceramic base 3 so as to close the recess 3-B, whereby the tantalum electrolytic capacitor 1 is obtained.

  The ceramic substrate 3 is made of a ceramic such as an alumina sintered body, and preferably a first metallized layer 3a is formed between one side surface and the bottom surface of the recess 3-B as shown in FIG. It is preferable to be formed on the upper surface of the stepped portion 3-C. Thereby, it becomes easy to electrically connect the anode lead terminal 2b of the tantalum electrolytic capacitor element 2 to the first metallized layer 3a, and the working efficiency is greatly improved.

  However, the formation position of the first metallized layer 3a is not limited to this, and it may be formed on the inner surface of the recess 3-B. For example, the first metallized layer 3a is formed independently of each other on the bottom surface of the recess 3-B so as not to be electrically connected to the second metallized layer 3b, and the anode lead 2b of the tantalum electrolytic capacitor element 2 is downward. It is good also as a structure bent and weld-joined to the 1st metallization layer 3a.

The ceramic container 6 is produced as follows, for example. When the ceramic substrate 3 is made of an alumina sintered body, an organic binder suitable for raw material powders such as aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), magnesium oxide (MgO), calcium oxide (CaO), and the like A solvent is added and mixed to form a slurry. This slurry is formed into a green sheet by a doctor blade method or a calender roll method and cut into a required size. Next, an appropriate punching process is performed to form the recesses 3-B and the steps 3-C in the plurality of green sheets.

  Then, a metal paste mainly composed of a metal powder such as tungsten (W) is printed and applied to these green sheets, and the first and second metallized layers 3a, 3b and the first and second conductor layers 3c, 3d. Form. Further, a punched portion to be the first groove 30 and the second groove 31 is formed on the outer surface, and a metal paste to be the first and second connection conductors 3e and 3f is applied to the inner surface of the punched portion. Next, these green sheets are laminated, and finally fired at a temperature of about 1600 ° C. to produce a ceramic container 6.

  In addition, on the exposed surface of each conductor (hereinafter also referred to as a wiring conductor) formed in the ceramic container 6 in this manner, a metal excellent in corrosion resistance and wettability with solder, for example, nickel having a thickness of 1 to 12 μm ( Ni) and gold (Au) having a thickness of 0.3 to 5 μm are preferably sequentially deposited by a plating method or the like. As a result, the wiring conductor is prevented from being oxidized and corroded by atmospheric oxygen, moisture, etc., and the first and second conductor layers 3c and 3d have improved wettability with the solder, and the external electric circuit board The bonding strength with the upper electrode (not shown) becomes stronger.

  If the thickness of the Ni layer is less than 1 μm, it is difficult to prevent the wiring conductor from being oxidized and corroded, and the bonding strength to the external electric circuit board is likely to be lowered. On the other hand, if the thickness of the Ni layer exceeds 12 μm, it takes a long time to form the plating, so that the mass productivity is likely to be lowered and the plating layer is easily peeled off due to the stress due to the difference in thermal expansion from the wiring conductor.

  Further, if the thickness of the Au layer is less than 0.3 μm, it becomes difficult to form an Au layer having a uniform thickness, and a portion where the Au layer is not formed may occur, and the effect of preventing oxidation corrosion The wettability with the solder tends to decrease. On the other hand, if the thickness of the Au layer exceeds 5 μm, it takes a long time to form the plating, and the mass productivity tends to decrease.

  The tantalum electrolytic capacitor element 2 is accommodated in the ceramic container 6, the anode lead terminal 2 b is connected to the first metallized layer 3 a, the cathode layer 2 c is connected to the second metallized layer 3 b, and the first and second surfaces on the lower surface are connected. Conductor layers 3c and 3d are joined to electrodes on the external electric circuit board via solder such as Au-Sn solder or Ag-Sn solder, so that the tantalum electrolytic capacitor element 2 and the external electric circuit board housed inside The upper electrode can be electrically connected.

  The ceramic container 6 of the present invention includes a first groove 30 and a second metallized layer 3b in which a first connection conductor 3e that electrically connects the first metallized layer 3a and the first conductor layer 3c is formed. And a second groove 31 in which a second connection conductor 3f for electrically connecting the second conductor layer 3d is formed.

  With this configuration, after the first groove 30 and the second groove 31 are formed at desired positions on the side surface of the ceramic base 3, the first connection conductor 3e and the second connection conductor 3f may be formed. The first connection conductor 3e and the second connection conductor 3f can be accurately formed at desired positions on the side surface of the ceramic base 3, and the formation of the first connection conductor 3e and the second connection conductor 3f is a castellation conductor formation. It becomes easy to form by the method. Thereby, the ceramic container 6 can be manufactured efficiently.

  Further, the first connection conductor 3e and the second connection conductor 3f are formed on the inner surfaces of the first groove 30 and the second groove 31 as compared with the case where the first connection conductor 3e and the second connection conductor 3f are formed on the flat side surface of the ceramic base 3. Since the bonding area between the first connection conductor 3e and the second connection conductor 3f and the ceramic base 3 can be increased, the bonding strength between the first connection conductor 3e and the second connection conductor 3f and the ceramic base 3 can be increased. In addition, the electrical resistance of the first connection conductor 3e and the second connection conductor 3f can be effectively reduced.

  In addition, since the upper and lower ends of the first groove 30 and the second groove 31 have chamfered portions 30a, 30b, 31a, 31b that are chamfered in a curved shape, the chamfer is not chamfered. Compared with, the conductive distance of the wiring conductor can be shortened, and since there are no corners where the electric resistance tends to be high when current flows, the electric resistance can be made small, and the desired performance is always achieved. Can be operated satisfactorily.

  Further, by reducing the electrical resistance of the first connection conductor 3e and the second connection conductor 3f, a large current can be passed through the first connection conductor 3e and the second connection conductor 3f, and the first metallization is performed. When the anode lead terminal 2b of the tantalum electrolytic capacitor element 2 is welded to the layer 3a by resistance welding, the electrical resistance is increased only at the contact portion between the first metallized layer 3a and the anode lead terminal 2b to increase the temperature. It becomes possible. Thereby, the anode lead terminal 2b can be efficiently and reliably welded to the first metallized layer 3a.

  In the welding joining of the anode lead terminal 2b and the first metallized layer 3a, a large current is passed between the first conductor layer 3c or the first connecting conductor 3e and the anode lead terminal 2b, so that the first metallized layer 3a. The contact portion is heated by the electrical resistance of the contact portion between the layer 3a and the anode lead terminal 2b, and the anode lead terminal 2b is welded to the first metallized layer 3c. Accordingly, it is preferable that the electric resistance other than the contact portion between the first metallized layer 3a and the anode lead terminal 2b is small.

  Furthermore, when the tantalum electrolytic capacitor 1 is mounted on the external electric circuit board using solder or the like, the bonding of the joint between the first connection conductor 3e and the second connection conductor 3f and the electrode of the external electric circuit board is performed. Since the area can be increased and a good meniscus can be formed, the bonding strength is high and the electrical resistance is low. The horizontal cross-sectional shape of the first groove 30 and the second groove 31 formed on the side surface of the ceramic substrate 3 is an arc shape in FIG. 2 (a) or a square corner portion in FIG. 2 (b). Various curved shapes such as a circular arc shape and a parabolic shape provided in the case can be used.

  Preferably, the thickness of the first connection conductor 3e located in the chamfered portions 30a and 30b of the first groove 30 is such that the portion other than the chamfered portions 30a and 30b of the first connection conductor 3e and the first metallized layer. 3a and the thickness of the second connection conductor 3f located at the chamfered portions 31a and 31b of the second groove 31 are larger than the thicknesses of the first conductor layer 3c and the chamfered portions 31a and 31b of the second connection conductor 3f. The first portions located in the chamfered portions 30a and 30b of the first groove 30 which are thicker than the portions other than 31b and the thicknesses of the second metallized layer 3b and the second conductor layer 3d and are likely to increase in electrical resistance. The electrical resistance can be further reduced in the connection conductor 3e and the second connection conductor 3f located in the chamfered portions 31a and 31b of the second groove 31. That is, the electric resistance of the wiring conductor can be made smaller, the tantalum electrolytic capacitor 1 can always be operated satisfactorily with a desired performance, and the anode lead terminal 2b is more efficiently formed by the first metallized layer 3a. And it can weld-join reliably.

Preferably, as shown in FIGS. 2A and 2B, the width of the first connection conductor 3e is wider than the width of the first metallized layer 3a, and the width of the second connection conductor 3f is second. By being wider than the width of the metallized layer 3b, the electrical resistance of the first connecting conductor 3e and the second connecting conductor 3f can be made smaller than that of the first metallized layer 3a and the second metallized layer 3b, respectively. . As a result, since a large current can flow through the first connection conductor 3e and the second connection conductor 3f, the tantalum electrolytic capacitor 1 can always be operated satisfactorily with desired performance, and the anode lead terminal 2b can be The first metallized layer 3a can be welded efficiently and reliably. The width of the first groove 30 is preferably larger than the width of the second groove 31 as shown in FIG. Thus, in the first metallized layer 3a that is welded to the anode lead terminal 2b, the resistance value of the first connecting conductor 3e is greatly reduced, and the first metalized layer 3a, the first connecting conductor 3e, and the first connecting conductor 3e The electrical resistance of the conductor composed of the conductor layer 3c is lowered, and the anode lead terminal 2b is more easily welded and joined to the first metallized layer 3a. Further, the width of the second groove 31 is set to the minimum necessary width that allows the tantalum electrolytic capacitor 1 to always operate satisfactorily with a desired performance, and the notch amount of the ceramic container 6 is minimized, so that the ceramic container 6 It is possible to suppress a decrease in the mechanical strength.

  Further, by making the widths of the first groove 30 and the second groove 31 different, the anode and the negative electrode of the tantalum electrolytic capacitor 1 can be easily distinguished, and the tantalum electrolytic capacitor 1 can be connected to the external electricity. Since erroneous mounting on a circuit board or the like can be prevented, the yield of products incorporating the tantalum electrolytic capacitor 1 can be greatly improved.

  As a method of forming the chamfered portions 30a, 30b, 31a, 31b of the first groove 30 and the second groove 31 which are chamfered at the upper end portion and the lower end portion thereof, When punching and forming the portion to be the groove 30 and the second groove 31, a chamfered portion is formed at the portion that becomes the upper end during punching by punching from the upper end of the green sheet at a higher speed than in the case of normal punching. . In order to form the chamfered portions 30a, 30b, 31a, and 31b at the lower end when punching, the chamfered portions 30a and 30b are pressed by pressing a metal pin having a curved surface similar to that of the chamfered portion after the punching process. , 31a, 31b are formed. Alternatively, the first groove 30 and the second groove 31 are punched into the green sheet to be the ceramic container 6, and then the upper end and lower end of the portion are the same as the chamfered portions 30a, 30b, 31a, 31b. The chamfered portions 30a, 30b, 31a and 31b can be formed by pressing a metal pin having a curved surface.

  As a method of making the first connection conductor 3e and the second connection conductor 3f located in the chamfered portions 30a, 30b, 31a, and 31b thicker than other wiring conductor portions, for example, the first metallized layer 3a, the first After applying the metal paste to be the conductor layer 3c, the second metallized layer 3b and the first conductor layer 3d so as to be applied also to the chamfered portions 30a, 30b, 31a and 31b, the inner surfaces of the grooves 30 and 31 In addition, a metal paste to be used for the first connection conductor 3e and the second connection conductor 3f may be applied to the chamfered portions 30a, 30b, 31a, 31b.

  Further, the thickness of the first connection conductor 3e and the second connection conductor 3f located in the chamfered portions 30a, 30b, 31a, 31b is about 1.1 to 1.5 times the thickness of the other wiring conductor portions. With this configuration, it is possible to effectively reduce the electric resistance and to operate as the tantalum electrolytic capacitor 1 more satisfactorily, and to further facilitate welding the anode lead terminal 2b to the first metallized layer 3a. it can.

  When the thicknesses of the first connection conductor 3e and the second connection conductor 3f located in the chamfered portions 30a, 30b, 31a, and 31b are less than 1.1 times the thickness of other wiring conductor portions, the electric resistance is reduced. If it exceeds 1.5 times, the thickness of the first connection conductor 3e and the second connection conductor 3f located at the chamfered portions 30a, 30b, 31a, 31b becomes too thick, and ceramic is likely to be reduced. The problem that the container 6 cannot be firmly adhered is likely to occur.

The metallized layer forming the first metallized layer 3a preferably contains molybdenum (Mo). When the anode lead terminal 2b of the tantalum electrolytic capacitor element 2 is welded to the first metallized layer 3a by a welding method, Since Mo has a high resistance value (5.7 × 10 ⁻⁸ Ωm), the resistance value can be increased at the contact portion between the first metallized layer 3a and the anode lead terminal 2b. A portion of the anode lead terminal 2b that contacts the first metallized layer 3a can be more easily dissolved.

  The tantalum electrolytic capacitor 1 of the present invention includes a ceramic container 6 of the present invention and an anode in which one end is embedded in the side surface of the sintered body 2a of tantalum powder and the other end is welded to the first metallized layer 3a. A tantalum electrolytic capacitor element 2 having a lead terminal 2b and a cathode layer 2c attached to the lower surface of the sintered body 2a and electrically connected to the second metallized layer 3b; And a lid 4 attached so as to close the recess 3-B.

  The tantalum electrolytic capacitor element 2 was obtained by sintering a molded body obtained by solidifying tantalum powder in which one end of an anode lead terminal 2b made of tantalum or the like was embedded and the other end protruded from a side surface. A dielectric oxide film layer (not shown) is formed on the sintered body 2a, a solid electrolyte layer (not shown) is formed outside the oxide film layer, and then a cathode layer 2c is formed on the outer periphery. .

  The other end of the anode lead terminal 2b is electrically connected to the first metallized layer 3a by a welding method such as resistance welding or laser welding. The first metallized layer 3a is electrically connected to the first conductor layer 3c via the first connection conductor 3e. That is, the first conductor layer 3c serves as the anode terminal of the tantalum electrolytic capacitor 1 connected to the electrode of the external wiring board.

The anode lead terminal 2b is made of, for example, tantalum or niobium. Preferably, the anode lead terminal 2b is made of tantalum, so that the anode lead terminal 2b can be firmly bonded to the tantalum sintered body 2a to be the tantalum electrolytic capacitor element 2. In addition, since tantalum has a high resistance value (13.5 × 10 ⁻⁸ Ωm), the anode lead terminal 2b can be easily melted, and the anode lead terminal 2b can be easily connected to the first metallized layer 3a. Can do.

  The cathode layer 2c may be electrically connected to the second metallized layer 3b via a conductive bonding material 5 such as an epoxy resin bonding material containing Ag. The second metallized layer 3b is electrically connected to the second conductor layer 3d via the second connection conductor 3f. That is, the second conductor layer 3d serves as the cathode terminal of the tantalum electrolytic capacitor 1 connected to the electrode of the external wiring board.

  According to the tantalum electrolytic capacitor 1 of the present invention thus configured, even if the first and second conductor layers 3c, 3d are electrically connected to the external electric circuit board using Pb-free solder, the ceramic substrate Since 3 has heat resistance, the ceramic base 3 is not deformed by heat and a gap is not generated in the ceramic container 6, so that airtightness can be maintained satisfactorily. Therefore, it is possible to effectively prevent moisture from entering the inside of the ceramic container 6 and effectively prevent occurrence of leakage current or occurrence of a defect due to a short circuit.

  Accordingly, the airtight reliability is remarkably improved as compared with the airtightness in the configuration having the conventional exterior resin and the lead frame, and the tantalum electrolytic capacitor element 2 malfunctions due to corrosion, short circuit, etc. due to moisture, foreign matter, harmful gas, or the like. Can be effectively prevented, and mechanical and electrical reliability can be maintained over a long period of time.

  Further, by accommodating the tantalum electrolytic capacitor element 2 in the ceramic container 6, the tantalum electrolytic capacitor 1 can be configured without using a lead frame, so that a tantalum electrolytic capacitor having a conventional exterior resin and a lead frame is provided. Compared to the above, the size can be reduced, and the mounting area on the external wiring board can be reduced.

  Furthermore, since the ceramic container 6 can be manufactured by a multi-cavity technique such as a known ceramic green sheet lamination method, it is extremely excellent in mass productivity.

  The present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the scope of the present invention. For example, although the case where the material of the ceramic substrate 3 of the tantalum electrolytic capacitor 1 is an alumina sintered body has been described, it may be made of other ceramics such as an aluminum nitride (AlN) sintered body or glass ceramics. When the tantalum electrolytic capacitor 1 is made of an AlN sintered body, heat during operation of the tantalum electrolytic capacitor 1 can be efficiently dissipated to the outside, so that the electrical characteristics of the tantalum electrolytic capacitor 1 can be maintained for a longer period.

  The tantalum electrolytic capacitor of the present invention is a communication device such as a mobile phone, an AV device such as a digital camera, a computer device such as a personal computer, an airbag, an anti-lock brake, etc. that require long-term reliability under severe environmental conditions. The present invention can also be suitably used in a wide range of fields including automobile equipment.

(A) is a top view which shows an example of embodiment of the ceramic container of this invention, (b) is sectional drawing of the ceramic container of Fig.1 (a). (A) is a principal part expanded sectional view which shows the 1st groove | channel of the ceramic container of FIG. 1, (b) shows the other example of embodiment of the ceramic container of this invention, and shows the 1st groove | channel of a ceramic container. It is a principal part expanded sectional view shown. It is a top view which shows the other example of embodiment of the ceramic container of this invention. It is sectional drawing which shows an example of embodiment of the tantalum electrolytic capacitor of this invention. It is sectional drawing which shows the example of the conventional tantalum electrolytic capacitor.

Explanation of symbols

1: Tantalum electrolytic capacitor 2: Tantalum electrolytic capacitor element 2a: Sintered body 2b: Anode lead terminal 2c: Cathode layer 3: Ceramic substrate 3a: First metallized layer 3b: Second metallized layer 3c: First conductor layer 3d: second conductor layer 3e: first connection conductor 3f: second connection conductor 3-B: concave portion 4: lid body 5: conductive adhesive 6: ceramic container
30: First groove
31: Second groove
30a, 30b, 31a, 31b: Chamfer

Claims (4)

A rectangular parallelepiped recess is formed at the center of the upper surface, the first metallized layer and the second metallized layer are formed independently of each other on the inner surface of the recess, and the first conductor layer and the second metallized layer are formed on the lower surface. A ceramic base formed independently of each other, and an inner surface of a first groove formed in a vertical direction on a side surface of the ceramic base; the first metallized layer and the first conductive layer; A first connection conductor for electrically connecting, and an inner surface of a second groove formed in a vertical direction on a side surface of the ceramic base, the second metallized layer and the second conductor layer A second connecting conductor that is electrically connected, and the first groove and the second groove have a chamfered portion in which an upper end portion and a lower end portion are chamfered in a curved shape. A ceramic container characterized by that. The thickness of the first connection conductor located in the chamfered portion of the first groove is determined by the portions of the first connection conductor other than the chamfered portion, the first metallized layer, and the first conductor layer. The thickness of the second connection conductor located at the chamfered portion of the second groove is larger than the thickness, and the thickness of the second connection conductor other than the chamfered portion, the second metallized layer, and the second The ceramic container according to claim 1, wherein each of the conductor layers is thicker than each of the conductor layers. The width of the first connection conductor is wider than that of the first metallization layer, and the width of the second connection conductor is wider than the width of the second metallization layer. Ceramic container. 4. The ceramic lead according to claim 1, and an anode lead having one end embedded in a side surface of a sintered body of tantalum powder and the other end welded to the first metallized layer. A tantalum electrolytic capacitor element having a terminal and a cathode layer deposited on the lower surface of the sintered body and electrically connected to the second metallization layer; A tantalum electrolytic capacitor comprising a lid attached in this manner.

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