JP5734075B2 - Solid electrolytic capacitor - Google Patents

Description

  The present invention relates to a solid electrolytic capacitor, and more particularly to a solid electrolytic capacitor used in a power circuit of an electronic device.

  In recent years, digital devices have become smaller and have higher performance, and the operation of CPUs and the like has also increased in frequency. Accordingly, noise removal and power supply voltage smoothing are required, and the role of electrolytic capacitors in decoupling circuits has become important. Therefore, there is an increasing demand for a solid electrolytic capacitor that is small in size and large in capacity and low in impedance.

  In order to achieve low impedance in a wide frequency range, it is necessary not only to reduce the equivalent series resistance (ESR) but also to further reduce the equivalent series inductance (ESL) that affects the performance at high frequencies. Thus, various solid electrolytic capacitors and noise filters have been studied.

  As one of them, a noise filter (three-terminal solid electrolytic capacitor) having a stripline structure, which is one of transmission line structures, has been developed as an electronic component having a wide band and excellent frequency characteristics.

  Here, the structure of the three-terminal solid electrolytic capacitor will be described with reference to the drawings. FIG. 3 is a diagram showing a configuration of a conventional three-terminal solid electrolytic capacitor. FIG. 3A is a cross-sectional view of the three-terminal solid electrolytic capacitor, and FIG. FIG. 3C is a schematic diagram showing a stripline structure, and FIG. 3D is a cross-sectional view taken along the line BB.

  First, the structure of the capacitor element 103 will be described. As shown in FIG. 3A, the anode body 121 is made of a valve metal having a rectangular plate shape or a rectangular foil shape, which is obtained by expanding the surface of aluminum or tantalum. A dielectric layer made of an oxide film is formed on the surface of the anode body 121.

  The anode body 121 is divided into three parts by two insulating parts 106 made of insulating resin, and both end parts are referred to as anode parts 101. At this time, the portion from the portion of the anode body 121 where the insulating portion 106 is formed to the end portion of the anode body 121 that becomes the anode portion 101 is removed with a laser or the like including the region where the surface of the dielectric layer is enlarged. . And after forming the solid electrolyte layer which consists of a conductive polymer layer in the surface of the dielectric material layer in the area | region of the anode body 121 pinched | interposed by the insulating part 106, a graphite layer and a silver layer are formed in order and a cathode layer is formed. The cathode part 104 is formed. Next, the metal piece 102 is welded to both ends of the anode part 101, and the capacitor | condenser element 103 is obtained.

  Next, the metal piece 102 is connected to the element side anode terminal 108 provided on the electrode substrate 207 by a conductive adhesive silver paste (not shown). Further, the cathode portion 104 and the element side cathode terminal 209 are connected by the conductive adhesive 105. In the case where a plurality of capacitor elements 103 are stacked, the conductive adhesive 105 is also used for connection of the respective cathode portions 104. Further, the element side anode terminal 108 and the mounting side anode terminal 110 and the element side cathode terminal 209 and the mounting side cathode terminal 111 are electrically connected by the via 112. After that, the exterior resin 113 is used for exterior packaging. In this way, the three-terminal solid electrolytic capacitor 300 is completed.

  FIG. 3B is a plan view of the electrode substrate 207 of the prior art as viewed from the side on which the capacitor element is mounted. The element-side cathode terminal 209 faces the cathode part of the capacitor element and is substantially equivalent (see FIG. 3B). Middle hatched part). The element-side anode terminal 108 and the element-side cathode terminal 209 are electrically connected to the mounting-side anode terminal and the mounting-side cathode terminal provided on the other surface through the via 112.

  The three-terminal solid electrolytic capacitor 300 has a stripline structure in which a portion where the cathode portion 104 is formed is one of transmission line structures. The stripline structure is a structure as shown in FIG. 3C of the schematic diagram, where the central part of the anode body of the capacitor element corresponds to the conductor 316, and the dielectric layer formed by the oxide film corresponds to the dielectric 317. The solid electrolyte layer and the cathode portion correspond to the conductor (GND) 318. By using the stripline structure, the impedance can be reduced even on the high frequency side. Such a technique is disclosed in Patent Document 1.

  3D is a cross-sectional view taken along the line BB in FIG. 3A. The anode portion 101 corresponds to a conductor and the exterior resin 113 corresponds to a dielectric. There is no conductor corresponding to the conductor (GND) in the cross section. Therefore, in the three-terminal solid electrolytic capacitor 300, this region which is in the vicinity of the anode part and the anode terminal does not have a transmission line structure.

  Further, in Patent Document 2 (particularly FIG. 7), in a three-terminal solid electrolytic capacitor, a reinforcing plate extending to an anode terminal portion used as a reinforcing material is a metal plate, and the cathode portion is electrically connected with a conductive paste. A technique is described that enhances the noise filter effect of the transmission line structure by connecting.

JP 2002-164760 A JP 2004-55699 A

  It is effective to use the transmission line structure described above in order to improve the noise removal effect in a frequency region called a high frequency region of about 100 MHz to 1 GHz by technical studies so far. However, even in the technology described in the prior art, there is a problem that it is difficult to further reduce the impedance in the vicinity of the anode portion and the anode terminal without increasing the number of members and manufacturing steps.

  Accordingly, an object of the present invention is to provide a solid electrolytic capacitor that does not increase the number of members and manufacturing man-hours, achieves low ESL particularly in a high-frequency region, and supports lower impedance.

In order to solve the above problems, the solid electrolytic capacitor of the present invention has an element-side anode terminal and an element-side cathode terminal on one surface of an electrode substrate, and vias a via on the other surface of the electrode substrate, A mounting-side anode terminal electrically connected to the element-side anode terminal, and a mounting-side cathode terminal electrically connected to the element-side cathode terminal;
A rectangular plate or rectangular foil-shaped anode body made of a valve action metal whose surface is enlarged, and having an anode part composed of both ends divided by two insulating parts made of insulating resin, and a region sandwiched between the insulating parts In addition, a dielectric layer, a solid electrolyte layer, and a cathode layer are sequentially formed, and a capacitor element having the cathode layer as a cathode portion is mounted on one surface of the electrode substrate,
The anode part and the element side anode terminal and the cathode part and the element side cathode terminal are respectively electrically connected, and the capacitor element is packaged with an exterior resin,
By providing the element-side cathode terminal in a region including a region facing the anode part, excluding the element-side anode terminal on one surface of the electrode substrate, the anode part and the anode part are opposed to each other. and the element-side cathode terminal position, and the exterior resin and forming a transmission line structure is between the element-side cathode terminal of the position opposing the anode portion and the anode portion.

The solid electrolytic capacitor of the present invention has an element-side anode terminal and an element-side cathode terminal on one surface of the electrode substrate, and is electrically connected to the element-side anode terminal through a via on the other surface of the electrode substrate. A mounting-side anode terminal that is electrically connected to the element-side cathode terminal,
An anode body made of a valve metal having a rectangular plate shape or a rectangular foil shape whose surface is enlarged is divided by an insulating portion made of an insulating resin, and one end portion is defined as an anode portion, and a dielectric layer is formed on the surface of the other region. The solid electrolyte layer and the cathode layer are sequentially formed, and a capacitor element having the cathode layer as a cathode portion is mounted on one surface of the electrode substrate,
The anode part, the element side anode terminal, the cathode part and the element side cathode terminal are each electrically connected, and the solid electrolytic capacitor formed by sheathing the capacitor element with an exterior resin,
By providing the element-side cathode terminal in a region including a region facing the anode part, excluding the element-side anode terminal on one surface of the electrode substrate, the anode part and the anode part are opposed to each other. and the element-side cathode terminal position, and the exterior resin and forming a transmission line structure is between the element-side cathode terminal of the position opposing the anode portion and the anode portion.

  In the solid electrolytic capacitor of the present invention, the transmission line structure is a microstrip line structure.

  The solid electrolytic capacitor according to the present invention is formed by forming an element-side cathode terminal in a region excluding the element-side anode terminal on the surface of the electrode substrate on which the capacitor element is mounted, thereby transmitting the anode part, the exterior resin, and the element-side cathode terminal. A line structure can be formed. As a result, it is possible to provide a solid electrolytic capacitor corresponding to a lower impedance without increasing the number of members and manufacturing man-hours and reducing the ESL particularly in the high frequency region.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of the 3 terminal type solid electrolytic capacitor in connection with Embodiment 1 of this invention, Fig.1 (a) is sectional drawing of a 3 terminal type solid electrolytic capacitor, FIG.1 (b) is a capacitor | condenser element mounting. FIG. 1C is a cross-sectional view taken along line AA, and FIG. 1D is a schematic diagram showing a microstrip line structure as viewed from the side. It is a figure which shows the structure of the solid electrolytic capacitor in connection with Embodiment 2 of this invention, Fig.2 (a) is sectional drawing of a solid electrolytic capacitor, FIG.2 (b) is the solid electrolytic capacitor seen from the capacitor | condenser element mounting side FIG. It is a figure which shows the structure of the conventional 3 terminal type solid electrolytic capacitor, Fig.3 (a) is sectional drawing of a 3 terminal type solid electrolytic capacitor, FIG.3 (b) is 3 terminal type solid seen from the capacitor | condenser element mounting side. The top view of the electrode substrate of an electrolytic capacitor, FIG.3 (c) is a schematic diagram showing stripline structure, FIG.3 (d) is sectional drawing cut | disconnected by the BB line. It is a figure which shows the structure of the conventional solid electrolytic capacitor, Fig.4 (a) is sectional drawing of a solid electrolytic capacitor, FIG.4 (b) is a top view of the electrode substrate of the solid electrolytic capacitor seen from the capacitor | condenser element mounting side.

  Embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram showing a configuration of a three-terminal solid electrolytic capacitor according to Embodiment 1 of the present invention. FIG. 1 (a) is a cross-sectional view of the three-terminal solid electrolytic capacitor, and FIG. FIG. 1C is a cross-sectional view taken along the line AA, and FIG. 1D shows a microstrip line structure, as viewed from the capacitor element mounting side. It is a schematic diagram.

  As shown in FIG. 1A, the capacitor element 103 has a structure similar to that of the prior art shown in FIG. 3, and the anode body 121 is made of a valve action metal obtained by surface-enhancing aluminum, tantalum, or the like. . At this time, a dielectric layer made of an oxide film is formed on the surface of the anode body 121.

  The anode body 121 is divided into three parts by two insulating parts 106 made of insulating resin, and both end parts are referred to as anode parts 101. At this time, the dielectric layer is removed by laser or the like in the region where the anode portion 101 and the insulating portion 106 are formed. And after forming the solid electrolyte layer which consists of a conductive polymer layer in the surface of the dielectric material layer in the area | region pinched | interposed by the two insulation parts 106 of the anode body 121, a graphite layer and a silver layer are formed in order, and a cathode A layer is formed as the cathode portion 104. Next, the metal piece 102 is welded to the end portion of the anode portion 101 by ultrasonic welding, electric welding, laser welding, or the like, and the capacitor element 103 is obtained.

  The connection between the capacitor element 103 and the electrode substrate 107 is the same as in the prior art, and the metal piece 102 bonded to both ends of the anode portion 101 is connected to the element-side anode terminal 108 provided on the electrode substrate 107 and the conductive adhesive silver paste. (Not shown). Subsequently, the cathode portion 104 and the element-side cathode terminal 109 are connected by the conductive adhesive 105. Note that the conductive adhesive 105 is also used for connection between the cathode portions 104 when a plurality of capacitor elements 103 are stacked, as in the prior art. The anode part 101 and the metal piece 102 are joined by electric welding, laser welding, or the like. In addition, the element-side anode terminal 108 and the mounting-side anode terminal 110 and the element-side cathode terminal 109 and the mounting-side cathode terminal 111 are electrically connected by a via 112. After that, it is packaged using an exterior resin 113 made of epoxy resin or the like. In this way, the three-terminal solid electrolytic capacitor 100 is completed.

  Here, the difference with the prior art in this invention is demonstrated. FIG. 1B shows the electrode substrate 107 before the capacitor element 103 is mounted. In the present invention, the element-side cathode terminal 109 is formed in a portion (hatched portion in the figure) excluding the element-side anode terminal 108 on the surface on which the capacitor element 103 of the electrode substrate 107 is mounted. That is, when the capacitor element 103 is mounted, the element side cathode terminal 109 is formed to have a large area up to the area facing the anode part 101 extending from the cathode part 104 to both sides and the periphery of the element side anode terminal 108. ing.

  Further, the above will be described with a cross-sectional structure. FIG.1 (c) is sectional drawing of the AA line of Fig.1 (a). Since the area of the element-side cathode terminal 109 is enlarged, the region facing the anode portion 101 has a pseudo transmission line structure (microstrip line structure) as shown in FIG. Is possible. Specifically, in FIGS. 1C and 1D, the anode portion 101 corresponds to the conductor 116, the exterior resin 113 corresponds to the dielectric 117, and the element-side cathode terminal 109 corresponds to the conductor 118 (GND). It corresponds to. With this transmission line structure, it is possible to provide a three-terminal solid electrolytic capacitor 100 having an effect of reducing ESL in the vicinity of the anode portion and the anode terminal, which cannot be handled by the prior art, and having reduced impedance. In addition, since the element-side cathode terminal 109 is enlarged, there is no increase in the number of members and an increase in height, and no increase in work process and manufacturing cost during assembly.

  In addition, regarding the formation range of the element-side cathode terminal 109 at the end portion on the short side of the electrode substrate 107 (between the element-side anode terminal 108 and the short side of the electrode substrate 107), a necessary level of ESL reduction can be achieved. If necessary, it may be appropriately reduced.

  The electrode substrate 107 is formed of glass epoxy resin or the like. Further, the element side anode terminal 108 and the element side cathode terminal 109 on the surface on the capacitor element mounting side, and the mounting side anode terminal 110 and the mounting side cathode terminal 111 on the surface to be mounted on the external substrate are copper foil or copper plating. Etc. are formed. The via 112 for conducting the element side connection electrode terminal and the mounting side electrode terminal is also formed by copper plating or the like.

(Embodiment 2)
In the second embodiment of the present invention, the structure of the present invention is applied to a two-terminal solid electrolytic capacitor.

  FIG. 2 is a diagram showing a configuration of a solid electrolytic capacitor according to Embodiment 2 of the present invention. FIG. 2 (a) is a cross-sectional view of the solid electrolytic capacitor, and FIG. 2 (b) is from the capacitor element mounting side. It is the top view of the electrode substrate of the seen solid electrolytic capacitor.

  As shown in FIG. 2A, an anode body 121 on which a dielectric layer made of an oxide film is formed is divided by an insulating portion 106 made of an insulating resin, and one side is used as an anode portion 101. Also in this case, as in the case of the three-terminal solid electrolytic capacitor, the dielectric layer is removed by a laser or the like in the region where the anode 101 and the insulating portion 106 of the anode 121 are formed. Then, a solid electrolyte layer is formed on the surface of the dielectric layer of the other anode body 121, and further, a graphite layer and a silver paste layer are formed as a cathode layer on the surface of the solid electrolyte layer to form the cathode portion 104.

  Subsequently, a metal piece 102 is joined to the end of the anode portion 101 to form a capacitor element 103. For joining, ultrasonic welding, electric welding, laser welding, or the like is used.

  Thereafter, the conductive adhesive 105 is applied to the cathode portion 104, and the capacitor element 103 is laminated. Subsequently, the anode part 101 and the metal piece 102 are joined by electric welding, laser welding, or the like to complete the capacitor element laminate.

  Next, the anode part 101 and the cathode part 104 are joined to the element side anode terminal 108 and the element side cathode terminal 109 of the electrode substrate 107 through a conductive adhesive silver paste (not shown) or a conductive adhesive 105, respectively. To do. The element side anode terminal 108 and the mounting side anode terminal 110, and the element side cathode terminal 109 and the mounting side cathode terminal 111 are electrically connected by a via 112. After that, it is packaged using an exterior resin 113 made of epoxy resin or the like. In this way, the solid electrolytic capacitor 200 is completed.

  As shown in FIG. 2B, the two-terminal solid electrolytic capacitor 200 of the present invention also has a portion excluding the element-side anode terminal 108 on the surface of the electrode substrate 107 on which the capacitor element 103 is mounted (hatched portion in the figure). An element-side cathode terminal 109 is formed on the substrate. That is, the area of the element-side cathode terminal 109 is increased to the area facing the anode section 101 extending from the cathode section 104 and the periphery of the element-side anode terminal 108.

  The cross-sectional structure is also the same as that of the first embodiment described above, and since the area of the element-side cathode terminal 109 is enlarged, the structure faces the anode portion 101. In the cross section taken along the line AA in FIG. In a pseudo manner, it is possible to adopt a transmission line structure (microstrip line structure) as shown in FIG. With this transmission line structure, it is possible to provide a two-terminal solid electrolytic capacitor having an effect of reducing ESL in the vicinity of the anode portion, which could not be dealt with by the prior art, and having reduced impedance. Further, since the element-side cathode terminal 109 is enlarged, there is no increase in the number of members or height, and no increase in the work process and manufacturing cost during assembly.

  It should be noted that the formation range of the element-side cathode terminal 109 between the element-side anode terminal 108 and the short side of the electrode substrate 107 is appropriately reduced if the required level of ESL can be reduced as in the first embodiment. Good.

  The element-side anode terminal 108 and the element-side cathode terminal 109, the mounting-side anode terminal 110, the mounting-side cathode terminal 111, and the via 112 are also formed of copper foil or copper plating.

Example 1
As the anode body, an aluminum foil whose surface was enlarged by etching was used. The anode body has a length of 6.0 mm, a width of 3.5 mm, and a thickness of 350 μm. A dielectric layer made of an oxide film was formed on the surface of the anode body. The anode body was divided into three by two insulating portions made of an insulating resin, and both end portions were anode portions. The dielectric layer was removed with a laser in the region from the insulating portion formation portion to the end portion of the anode portion on the surface of the anode body.

  Next, on the surface of the dielectric layer at the center of the anode body sandwiched between the two insulating portions, as a solid electrolyte layer, iron benzenesulfonate is used as an oxidizing agent, and 3,4-ethylenedioxythiophene is used as a monomer. A layer of conductive polymer polythiophene was formed by chemical oxidative polymerization. Further, a graphite layer and a silver paste layer were formed on the surface to form a cathode part.

  Thereafter, a metal piece in which a silver plate was applied to a copper plate having a thickness of 60 μm was joined to the end portions of the two anode portions by ultrasonic welding to obtain a capacitor element. After applying a conductive adhesive to the cathode part of this capacitor element and laminating three capacitor elements, the cathode parts were electrically joined by drying at 150 ° C. for 60 minutes.

  Further, a capacitor element laminate was fabricated in which the end of the anode part and the metal piece were joined by laser welding to laminate three pieces.

  In the electrode substrate, the element-side cathode terminal was formed in a region excluding the element-side anode terminal on the surface on which the capacitor element was mounted. The base material of the electrode substrate was a glass epoxy resin having a length of 8.5 mm, a width of 5.3 mm, and a thickness of 100 μm. The element side anode terminal and the element side cathode terminal were formed by copper plating, and the plating thickness was 20 μm. Similarly, the via was formed by copper plating, and the element side electrode terminal and the mounting side electrode terminal were electrically connected to each other.

  Subsequently, the anode part and the cathode part of the produced capacitor element laminate were connected to the element-side anode terminal and the element-side cathode terminal via a conductive adhesive containing silver, respectively.

  Thereafter, the capacitor element mounted on the electrode substrate was molded and packaged with an exterior resin made of an epoxy resin containing a glass filler. As a result, a three-terminal solid electrolytic capacitor of the present invention was obtained. The production quantity was 100.

(Example 2)
Example 2 is the same as Example 1 except that the capacitor element has a two-terminal structure and the electrode substrate also has a two-terminal structure. That is, the element-side cathode terminal was formed in a region excluding the element-side anode terminal on the surface of the electrode substrate on which the capacitor element was mounted, and a two-terminal solid electrolytic capacitor of the present invention was obtained. The production quantity was 100.

(Comparative Example 1)
The three-terminal solid electrolytic capacitor of Comparative Example 1 is the same as Example 1 of the present invention except that the element-side cathode terminal area of the electrode substrate is formed in a substantially equivalent area facing the cathode part of the capacitor element. It is the composition. The production quantity was 100.

(Comparative Example 2)
4A and 4B are diagrams showing a configuration of a conventional solid electrolytic capacitor. FIG. 4A is a cross-sectional view of the solid electrolytic capacitor, and FIG. 4B is an electrode substrate of the solid electrolytic capacitor as viewed from the capacitor element mounting side. FIG. 4A and 4B, the two-terminal solid electrolytic capacitor 400 of Comparative Example 2 has a capacitor element 103 and an electrode substrate 207 having a two-terminal structure, and the element side of the electrode substrate 207 is the element side. The structure is the same as that of the second embodiment of the present invention except that the area of the cathode terminal 209 is formed in a substantially equivalent area facing the cathode portion 104 of the capacitor element 103. The production quantity was 100.

  Table 1 shows the ESL values of Example 1, Example 2, Comparative Example 1, and Comparative Example 2. The value of ESL was calculated by measuring attenuation characteristics (S21) with a network analyzer in a three-terminal solid electrolytic capacitor. For a two-terminal solid electrolytic capacitor, measurement was performed using an impedance analyzer. The measurement frequency is 1 GHz and the number of measurements is 100.

  From the results shown in Table 1, the ESL values of Examples 1 and 2 were lower than those of Comparative Examples 1 and 2, and the effects of the present invention could be confirmed.

  The embodiments of the present invention have been described above using the embodiments. However, the present invention is not limited to these embodiments, and the present invention is not limited to the scope of the present invention. Included in the invention. That is, the present invention also includes various variations and modifications that could be made by those skilled in the art.

100, 300 Three-terminal type solid electrolytic capacitor 101 Anode part 102 Metal piece 103 Capacitor element 104 Cathode part 105 Conductive adhesive 106 Insulating part 107, 207 Electrode substrate 108 Element side anode terminal 109, 209 Element side cathode terminal 110 Mounting side anode Terminal 111 Mounting side cathode terminal 112 Via 113 Exterior resin 116, 316 Conductor 117, 317 Dielectric 118, 318 Conductor (GND)
121 Anode body 200, 400 Solid electrolyte capacitor

Claims (3)

A mounting-side anode terminal that has an element-side anode terminal and an element-side cathode terminal on one surface of the electrode substrate, and is electrically connected to the element-side anode terminal through a via on the other surface of the electrode substrate; A mounting-side cathode terminal that is electrically connected to the cathode terminal;
A rectangular plate or rectangular foil-shaped anode body made of a valve action metal whose surface is enlarged, and having an anode part composed of both ends divided by two insulating parts made of insulating resin, and a region sandwiched between the insulating parts In addition, a dielectric layer, a solid electrolyte layer, and a cathode layer are sequentially formed, and a capacitor element having the cathode layer as a cathode portion is mounted on one surface of the electrode substrate,
The anode part and the element side anode terminal and the cathode part and the element side cathode terminal are respectively electrically connected, and the capacitor element is packaged with an exterior resin,
By providing the element-side cathode terminal in a region including a region facing the anode part, excluding the element-side anode terminal on one surface of the electrode substrate, the anode part and the anode part are opposed to each other. the solid electrolytic capacitor and the element-side cathode terminal position, the exterior resin is between the element-side cathode terminal of the position opposing the anode portion and the anode portion and forming a transmission line structure. A mounting-side anode terminal that has an element-side anode terminal and an element-side cathode terminal on one surface of the electrode substrate, and is electrically connected to the element-side anode terminal through a via on the other surface of the electrode substrate; A mounting-side cathode terminal that is electrically connected to the cathode terminal;
An anode body made of a valve metal having a rectangular plate shape or a rectangular foil shape whose surface is enlarged is divided by an insulating portion made of an insulating resin, and one end portion is defined as an anode portion, and a dielectric layer is formed on the surface of the other region. The solid electrolyte layer and the cathode layer are sequentially formed, and a capacitor element having the cathode layer as a cathode portion is mounted on one surface of the electrode substrate,
The anode part, the element side anode terminal, the cathode part and the element side cathode terminal are each electrically connected, and the solid electrolytic capacitor formed by sheathing the capacitor element with an exterior resin,
By providing the element-side cathode terminal in a region including a region facing the anode part, excluding the element-side anode terminal on one surface of the electrode substrate, the anode part and the anode part are opposed to each other. the solid electrolytic capacitor and the element-side cathode terminal position, the exterior resin is between the element-side cathode terminal of the position opposing the anode portion and the anode portion and forming a transmission line structure.   The solid electrolytic capacitor according to claim 1, wherein the transmission line structure is a microstrip line structure.

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