JP4645490B2 - High frequency filter - Google Patents

Description

  The present invention relates to a high frequency filter, and more particularly to a high frequency filter that is mounted on a printed circuit board and can remove noise in a wide band.

  With the development of technology in recent years, electronic devices represented by computers have come to operate at very high speeds, and accordingly, noise over a wide band from low frequency to high frequency range is emitted from electronic devices. It has become to. In order to remove such noise, for example, Patent Document 1 proposes a distributed constant type noise filter (see, for example, Patent Document 1).

  For example, Patent Document 2 proposes a transmission line type noise filter. In the filter of this structure, the length is often determined depending on the lowest frequency in the frequency region to be removed. Specifically, as described in the same document, a length of ¼ wavelength or more is required, and a domestic standard (common name: VCCI) of radio wave interference voluntary standards such as information processing devices in Japan. In order to filter 30 MHz which is the lowest frequency in the frequency range of class B), for example, when an aluminum electrolytic capacitor structure is used as a base, a length of about 1 mm is required. A length of several centimeters is required.

On the other hand, a multilayer solid electrolytic capacitor element has been proposed for the purpose of increasing the capacitance (see, for example, Patent Document 3). The multilayer solid electrolytic capacitor described in this document can be a high-frequency filter, and a high-frequency filter that can cope with a low frequency by increasing the capacity.
JP 2002-164760 A JP 2004-15706 A JP 2004-289142 A

  However, the conventional high frequency filter has the following problems. For example, a noise filter as proposed in Patent Document 1 is resin-sealed or the like to improve environmental resistance. In consideration of automatically mounting such a noise filter on a printed circuit board, resin sealing with a transfer mold is one option. However, in the transfer mold, the temperature rises to about 180 ° C. during the process. Therefore, when a high frequency filter is formed by laminating noise filters in layers, due to the difference in thermal expansion coefficient between the metals constituting each noise filter, There arises a problem that the high-frequency filter, which is a stationary object, is warped in the mold resin. The same applies to the noise filter proposed in Patent Document 2, and there is a problem that the metal plate warps due to the high temperature applied in the resin sealing process at the time of manufacturing the noise filter, and the noise filter warps.

  In addition, the multilayer capacitor proposed in Patent Document 3 is effective for increasing the capacitance, but on the other hand, the distance from the electrode terminal to the filter element located far from the electrode terminal becomes large. There is a problem that the equivalent series resistance or equivalent series inductance of the entire element increases. Increasing the equivalent series resistance affects the direction of reducing the ability of the high frequency filter, and increasing the equivalent series inductance affects the direction of lowering the upper limit frequency of the high frequency filter. Since the equivalent series resistance and equivalent series inductance are dominated by the resistance component and inductance component parasitic on the cathode, it is necessary to reduce the resistance component and the inductance component at the cathode in order to improve the characteristics of the high frequency filter. . Similarly to the above, the multilayer capacitor of Patent Document 3 also has a problem of warpage of the metal plate due to high temperature when resin-sealing at the time of manufacture.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a high-frequency filter in which element deformation due to temperature change in a manufacturing process is small. It is another object of the present invention to provide a high frequency filter in which the equivalent series resistance and the equivalent series inductance do not increase.

  In order to solve the above problems, a high-frequency filter according to the present invention includes a filter element portion formed by laminating a plurality of filter elements each provided with a cathode via a dielectric layer around a substantially plate-shaped anode, and the cathode A metal member surrounding at least three surfaces of the filter element portion so as to face each other, and an adhesive conductive material filled between the filter element portion and the metal member.

  According to the present invention, the metal member is provided so as to surround at least three surfaces of the filter element portion formed by laminating the plurality of filter elements, and the adhesive conductive property is provided between the filter element portion and the metal member. Since the material is filled, the filter element portion adheres to at least three surfaces to a metal member that is rigid against warping. As a result, the warp of the filter element portion can be prevented by the rigid metal member. Furthermore, according to the present invention, since the cathodes of all the laminated filter elements are directly conducted to the metal member through the conductive material, the equivalent series resistance and equivalent series inductance of the high frequency filter can be reduced. The capability of the high frequency filter can be improved and the upper limit frequency can be expanded.

  In the high frequency filter of the present invention, (1) the metal member has a substantially U shape, and the filter element portion is accommodated therein, or (2) the metal member has a cylindrical shape, It is preferable that the filter element portion is accommodated therein.

  According to the inventions of (1) and (2), since the metal member is not a single flat plate but a three-dimensional structure surrounding at least three surfaces of the filter element part, the strength against warping of the filter element part is increased. Can be raised. As a result, even if a thermal history such as resin sealing is passed in the assembly process, the possibility of warping of the filter element and the filter element portion can be further reduced.

  The high-frequency filter of the present invention has a three-terminal structure or a four-terminal structure.

  In the high frequency filter of the present invention, the metal member corresponds to a cathode of the high frequency filter. According to this invention, the metal member surrounds at least three surfaces of the filter element portion so as to face the cathode of the filter element, and the filter element portion and the metal member are bonded via the conductive material. The metal member is electrically connected to each cathode of the filter element and acts as a substantial cathode.

  In the high frequency filter of the present invention, the metal member and the filter element portion are sealed with a resin. According to this invention, since the structure consisting of the metal member and the filter element portion is sealed with the resin, the entire structure is excellent in strength.

  According to the high frequency filter of the present invention, the filter element portion is bonded to the metal member that is rigid against warping on at least three surfaces, and therefore, the warp of the filter element portion can be prevented by the rigid metal member. Furthermore, if the metal member has a three-dimensional structure that surrounds three surfaces, the strength against warping of the filter element portion can be increased, and even if it undergoes a thermal history such as resin sealing in the assembly process, The possibility of warping of the filter element, the filter element portion, or the metal member can be further reduced.

  Furthermore, according to the high frequency filter of the present invention, since the cathodes of all the laminated filter elements are directly conducted to the metal member through the conductive material, the cathode of the filter element and the metal member are electrically connected in a larger area. Thus, the parasitic resistance and the parasitic inductance from the filter element to the metal member can be reduced, and the equivalent series resistance and the equivalent series inductance can be reduced. As a result, it is possible to provide a high frequency filter that realizes excellent high frequency characteristics.

  Next, the high frequency filter of this invention is demonstrated in detail with reference to drawings.

(High frequency filter)
1 is a schematic transmission perspective view showing an example of the high-frequency filter of the present invention, FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 1, and FIG. 3 shows a filter element portion. It is a perspective view of the filter element which comprises. As shown in FIGS. 1 to 3, the high-frequency filter 1 of the present invention is formed by laminating a plurality of filter elements 21 each provided with a cathode 211 through a dielectric layer 213 around a substantially plate-like anode 212. The filter element 20, the metal member 11 surrounding at least three surfaces of the filter element 20 so as to face the cathode 211, and the adhesive conductive material 31 filled between the filter element 20 and the metal member 11. And at least.

  Further, as shown in FIGS. 1 and 2, the high-frequency filter 1 of the present invention is such that the filter element portion 20, the metal member 11, and the conductive material 31 are all covered with a resin 41 and the whole is sealed. preferable. Note that the high-frequency filter shown in FIG. 1 also includes the conductive material 31, but the conductive material 31 is omitted for convenience.

  As shown in FIG. 3, the filter element 21 applied to the present invention has a structure in which a cathode 211 is provided around a substantially plate-like anode 212 via a dielectric layer 213, and has a transmission line structure. This is a distributed constant noise filter of the three-terminal capacitor type having The filter element 21 having such a configuration is a distributed constant type noise filter that can generate a low impedance continuous over a wide range by controlling the width, length, and thickness of the distributed constant circuit forming portion.

  Here, the basic configuration of the distributed constant noise filter will be described. The basic configuration of the distributed constant type noise filter includes a dielectric (dielectric layer 213) formed so as to surround a substantially flat metal plate (anode 212), and further surrounds the dielectric (dielectric layer 213). In this way, a distributed constant circuit forming part composed of a conductive cathode terminal (cathode 211), a cathode terminal (cathode 211) conducting to this distributed constant circuit forming part, and a part of the metal plate (anode 212) are dielectric ( It has an electrode part (electrode part 214) protruding from the dielectric layer 213) and an anode terminal (anode terminals 12 and 13) electrically connected to the electrode part (electrode part 214). The length in the short side direction of the distributed constant circuit forming unit, the length in the long side direction of the distributed constant circuit forming unit, and the effective thickness of the distributed constant circuit forming unit are based on the dielectric constant of the distributed constant circuit forming unit. It consists of a set configuration. The distributed constant type noise filter having such a configuration can reduce the impedance over a wide frequency band and further reduce the impedance on the high frequency side, thereby eliminating electrical noise in a wide band, particularly at a high frequency. It becomes a distributed constant type noise filter which performs. The parentheses indicate the configuration of the filter element 21 in the present invention corresponding to the basic configuration of the distributed constant noise filter, and the filter element 21 configuring the present invention has the basic configuration of the distributed constant noise filter. Yes.

  As the filter element 21, for example, an aluminum solid electrolytic capacitor will be described as an example. The aluminum solid electrolytic capacitor as the filter element 21 uses foil-like aluminum as the anode 212, has an uneven surface by etching, and further forms an oxide film as the dielectric layer 213 on the surface. Furthermore, as the cathode 211 provided in a form facing the surface of the oxide film, a cathode in which a solid electrolyte layer such as a conductive polymer layer, graphite, and a silver paste layer are formed in that order can be cited. Such a structure is a structure similar to a stripline structure. That is, the line conductor constituting the strip line structure is aluminum at the center, the dielectric corresponds to the oxide film, and the ground conductor corresponds to the solid electrolyte layer, the graphite, and the silver paste layer. Since the oxide film is formed by an etching process that increases the surface area, the same shape can provide a larger capacitance than a ceramic capacitor using a single material, and has a structure suitable for a distributed constant noise filter. It has become. Other examples of using the oxide film as the dielectric layer 213 include a tantalum capacitor.

  The example of the filter element 21 is not limited to the above-described example of the aluminum solid electrolytic capacitor, and the filter element 21 may be made of other materials as long as it has the same configuration and the same filter function. It can be used as the filter element 21 applicable to the invention.

  The filter element section 20 is a substantially rectangular structure formed by stacking a plurality of the filter elements 21 described above. In FIG. 1 and FIG. 2, five filter elements 21 are stacked. There is no need, and there may be two to four, six or more, or one. The filter element portion 20 is configured by superposing the cathode portions of the filter elements 21 with an adhesive material interposed therebetween. The adhesive material may be the same as or similar to the conductive material 31 filling the space between the cathode portion of the filter element portion 20 and the metal member 11, or other adhesive material having no conductivity. (For example, a general adhesive resin) may be used. When the cathode portions of the filter elements 21 are bonded and overlapped with another adhesive material having no conductivity, the conductivity filling the space between the cathode portion of the filter element portion 20 and the metal member 11 is used. It is necessary to make the cathode 211 of each filter element 21 and the metal member 11 conductive by the material 31.

  The metal member 11 surrounds at least three surfaces of the substantially rectangular filter element portion 20 so as to face the cathode 211 of the filter element 21. As the metal member 11, generally, a copper plate processed (molded or welded) is preferably used, but another conductive metal member such as an aluminum plate may be processed. In addition, since the metal member 11 is processed into a shape that surrounds at least three surfaces of the substantially rectangular filter element portion 20, the metal member 11 has a greater rigidity against warping than a plate made of a single plane. Can do.

  The metal member 11 only needs to continuously surround at least three surfaces of the substantially rectangular filter element portion 20, and the position thereof is not particularly limited, but the U-shaped metal member 11 shown in FIG. It surrounds both the left and right surfaces parallel to the laminating direction of the flat filter element 21 and one surface of the upper and lower surfaces (filter element laminating surface) in the laminating direction. This form can reduce the parasitic resistance and the parasitic inductance from the filter element to the metal member together with the effect of preventing the warp (the equivalent series resistance and the equivalent series inductance can be further reduced), and in electrical characteristics. Is also advantageous. The metal member 11 may continuously surround the other three surfaces. For example, the metal member 11 may be one of the upper and lower surfaces in the stacking direction and the left and right surfaces parallel to the stacking direction. In this embodiment, the metal members 11 are arranged on both the upper and lower surfaces which are the warping direction, so that the warpage preventing effect is particularly excellent. In addition, a rectangular or circular cylindrical shape that continuously surrounds all four surfaces (see, for example, FIG. 4E) is excellent in the effect of preventing warpage and is advantageous in terms of electrical characteristics. Moreover, even if it surrounds 3 surfaces, it does not need to surround all of each surface, and may surround at least one part (for example, refer FIG.4 (b)).

  Further, the length of the metal member 11 in the longitudinal direction (the left-right direction in FIG. 1 and the longitudinal direction of the filter element 21) may be approximately the same as the length of the filter element 21, but the metal member 11 and the filter It is preferable that the length is slightly short as shown in FIG. 1 so that the conductive material 31 filled between the element portion 20 and the cathode portion does not contact the anode 212 of each filter element 21.

  FIG. 4 is a cross-sectional view showing an example of a metal member applied to the present invention. In this invention, the metal member 11 which consists of various forms can be used, and the form which covers at least 3 surfaces of the cathode part of the filter element part 20 continuously as a result of shape | molding or welding a metal plate, such as a copper plate. What was processed into can be used. For example, as shown in FIG. 4 (a), it may be a bowl-shaped metal member having a flat bottom surface and curved side surfaces, or as shown in FIG. 4 (b), the length of one side surface. However, it may be a metal member that is shorter than the length that surrounds the entire surface of the filter element portion 20 that faces the side surface, and as shown in FIG. The metal member may be a U-shaped metal member that is continuously enclosed, or may be a metal member having a shape in which the opening is wider than the bottom, as shown in FIG. As shown to e), a cylindrical metal member may be sufficient and the metal member which consists of forms other than these may be sufficient.

  The cathode portion of the filter element portion 20 constituting the present invention is accommodated in the metal member 11 having a rigid three-dimensional structure via the adhesive conductive material 31, so that the filter element portion 20 can be prevented from warping. Strength can be increased. As a result, the possibility of warping of the filter element 21, the filter element portion 20, the metal member 11, etc. can be further reduced even if a thermal history such as resin sealing is passed in the assembly process.

  The conductive material 31 has adhesiveness and is filled between the filter element portion 20 and the metal member 11 as shown in FIG. Preferred examples of the conductive material 31 include an adhesive paste material containing conductive particles such as silver paste, but other materials having adhesiveness and conductivity may be used.

  Since the conductive material 31 bonds the filter element portion 20 and the metal member 11 over a large area, the filter element portion 20 adheres to the metal member 11 in an adhesive conductive manner in cooperation with the rigid metal member 11. The material 31 is reinforced with the material 31. As a result, even when a load such as heat is applied during the manufacturing process of the high frequency filter, it is possible to prevent the filter element portion 20 from undergoing a shape change such as a warp.

  In addition, since the conductive material 31 fills the space between the filter element portion 20 and the metal member 11, the cathode 211 and the metal member 11 of each filter element 21 constituting the filter element portion 20 are electrically connected. As a result, the metal member 11 corresponds to the cathode of the high frequency filter 1. Furthermore, since the cathodes 211 of all the laminated filter elements 21 are directly conducted to the metal member 11 through the conductive material 31, the equivalent series resistance and equivalent series inductance of the high frequency filter 1 can be reduced, and the high frequency The capability of the filter 1 can be improved and the upper limit frequency can be expanded.

  As shown in FIGS. 1 and 2, the structure having the metal member 11 and the filter element portion 20 is sealed with a resin 41. The high-frequency filter 1 of the present invention is an integral structure excellent in strength as a whole by such a resin 41. As resin 41, what is used as sealing resin of a general electronic component can be used, For example, an epoxy resin etc. can be illustrated. An integrated structure formed by sealing with such a resin is almost in the final product form if an electrode portion or the like is subsequently provided. Since this invention has the said metal member 11 and has a curvature prevention effect, even if it is a case where heat generate | occur | produces, for example when sealing with the resin 41, the curvature like the conventional will not generate | occur | produce. Therefore, there is an advantage that the degree of freedom of selection of the sealing resin is increased, and further, the sealing conditions can be changed to reduce the man-hours.

  More specifically, the filter element unit 20 will be described in detail. The anodes 212 at both ends of each filter element 21 constituting the filter element unit 20 are electrically connected to each other by the connecting element 51 (see FIG. 1). The anode part is configured, and the anode part is electrically connected to the anode terminals 12 and 13, respectively. A copper plate or the like is preferably used as the connection terminal 51, and a conductive metal plate such as a copper plate is preferably used as the anode terminals 12 and 13.

  As described above, the high-frequency filter 1 of the present invention has the filter element portion 20 in which a plurality of filter elements 21 are stacked, the cathode portion surrounded by the metal member 11 with the conductive material 31 interposed therebetween, and the cathode And anode portions provided at both ends of the portion.

  For example, when a metal member 11 made of copper and a filter element portion 20 in which a filter element 21 made of, for example, aluminum is laminated are laminated with an epoxy resin as a protective resin 41 by a transfer molding method, for example. As described above, the stress in the warping direction is generated with the thermal history of the resin sealing process. However, in the present invention, the metal member 11 is provided so as to surround at least three surfaces of the filter element portion 20 (in FIG. 1, the filter element portion 20 is accommodated in the U-shaped metal member 11 surrounding the three surfaces. The strength against the warp of the metal member 11 is increased as compared with the case without the characteristics of the present invention.

(Filter characteristics of high frequency filter)
FIG. 5 is a graph of the filter characteristic (attenuation characteristic: S21) of the high-frequency filter when the equivalent series resistance changes, and FIG. 6 is a graph of the filter characteristic (attenuation characteristic: S21) of the high-frequency filter when the equivalent series inductance changes. ). In each figure, the lower the vertical axis of the graph, the better the filter characteristics. As shown in FIG. 5, the relationship between the equivalent series resistance (ESR) and the filter characteristics of the high-frequency filter 1 of the present invention becomes worse as the equivalent series resistance (ESR) increases. The relationship between the equivalent series inductance (ESL) of the frequency filter 1 of the present invention and the filter characteristics is such that the upper limit frequency of the filter characteristics decreases as the equivalent series inductance (ESL) increases, as shown in FIG.

  In the high frequency filter 1 of the present invention, the equivalent series resistance (ESR) and equivalent series inductance (ESL) are generally dominated by the resistance and inductance of the portion of the filter element 21 connected from the cathode 211 to the conductive material 31 and the metal member 11. It is. Therefore, reducing the resistance and inductance of this part leads to reduction of equivalent series resistance (ESR) and equivalent series inductance (ESL), and consequently improvement of filter characteristics.

  1 and FIG. 2, the metal member 11 surrounds the filter element portion 20 in a “U” shape, and the cathode 211 (cathode portion) and the metal member of each filter element 21 constituting the filter element portion 20. 11 is connected by a conductive material 31. Thereby, the cathode part of the filter element part 20 is electrically connected to the metal member 11 via the conductive material 31 not only on the bottom face but also on the side face. Since the electrical resistance and the inductance are reduced in inverse proportion to the cross-sectional area thereof, the structure of the present invention increases the contact area between the metal member 11 and the filter element portion 20, reduces the connection resistance, and reduces the inductance. Become. As a result, the equivalent series resistance (ESR) and the equivalent series inductance (ESL) of the filter element are reduced, and the effect of improving the characteristics of the high frequency filter 1 can be obtained.

  Next, in order to understand the filter characteristics of the high frequency filter of the present invention, the conventional high frequency filter and the high frequency filter of the present invention will be specifically described.

  FIG. 7 shows a cross-sectional view of a conventional high-frequency filter 70 when viewed from the same direction as FIG. As shown in FIG. 6, the metal member 61 is not provided so as to surround three or more surfaces of the filter element portion 72 in which a plurality of filter elements 71 are stacked, and the metal member 61 is opposed only to the bottom surface of the filter element portion 72. When the member 61 is provided, there is only one filter element 71 directly connected to the metal member 61, and the filter elements 71 stacked on the filter element 71 are indirectly connected via the lower filter element 71. Will be connected. FIG. 8 shows an equivalent circuit of the high-frequency filter 70 in this case. FIG. 8 shows the cross-sectional dimensions of each filter element 71 shown in FIG. 7 with a width of 1.0 mm and a height of 0.4 mm, and the thickness of the conductive material 81 between the filter elements 71 is 0.2 mm. The thickness of the conductive material 82 between the element 71 and the metal member 61 is 0.2 mm. In FIG. 8, the conductive material between the lowermost filter element 71 and the metal member 61 is shown. The resistance value and the inductance value of the conductive material in each part when the resistance and inductance of 82 are R and L, respectively, are described.

  FIG. 9 shows an equivalent circuit of the high frequency filter 1 of the present invention having the configuration shown in FIG. 9 shows a cross-sectional dimension of each filter element 21 shown in FIG. 2 having a width of 1.0 mm, a height of 0.4 mm, a thickness of the conductive material 31 between the filter elements 21 of 0.2 mm, and the lowermost filter. The thickness of the conductive material 31 between the element 21 and the metal member 11 is 0.2 mm, and the thickness of the conductive material 31 between the cathode 211 on the side surface of the filter element 21 and the metal member 11 facing the side surface. In addition, an equivalent circuit is shown in a simplified case where the thickness is 0.4 mm, and other than the lowermost filter element 21 is electrically connected to the metal member 11 only on the side surface.

  When a plurality of filter elements are stacked to form one high-frequency filter, this corresponds to the fact that each filter element is inserted in parallel in the circuit. Therefore, in FIG. 8, the equivalent of the first filter element is obtained. The series resistance and equivalent series inductance are R and L, and are grounded via the R and L.

  In addition, the second filter element is connected to the first filter element via R and L immediately below, but in detail, L, R, the surface of the first filter element, L, Grounded via R. At this time, the width × thickness of the cross section of the conductive material in contact with the filter element is 1.0 mm × 0.2 mm in the horizontal portion and 0.4 mm × 0.4 mm in the vertical portion, respectively. The resistance and inductance of the surface of the filter element can be calculated as 2.5R and 2.5L, respectively. In this case, the equivalent series resistance and equivalent series inductance as a whole are R + 2.5R + R = 4.5R and L + 2.5L + L = 4.5L, respectively.

  Similarly, the equivalent series resistance and equivalent series inductance of the third to fifth filter elements are 8R, 11.5R, 15R, 8L, 11.5L, and 15L, respectively. Therefore, when the filter elements 71 are laminated and connected to the cathode (metal member 61) only at the lowermost surface as in the conventional high frequency filter 70 shown in FIG. The combination of the resistance and the equivalent series inductance is 0.67R and 0.67L because the resistance component and the inductance component of each filter element 71 are connected in parallel.

  On the other hand, in the high frequency filter 1 of the present invention, as shown in FIG. 9, the equivalent series resistance and equivalent series inductance of the first filter element are 0.7R, 0.7L, and 5 from the second filter element. The equivalent series resistance and equivalent series inductance of the first filter element are 2.5R and 2.5L. Therefore, when the filter elements are stacked and connected to the cathode (metal member 11) on three sides as in the high-frequency filter 1 of the present invention having the form shown in FIG. The combination of the equivalent series resistance and the equivalent series inductance is 0.09R and 0.09L.

  As described above, according to the high frequency filter 1 of the present invention, the equivalent series resistance and the equivalent series inductance of the high frequency filter can be reduced, and as a result, the effect that the filter characteristics are improved can be obtained.

(Manufacturing method of high frequency filter)
Next, the manufacturing method of the high frequency filter of this invention is demonstrated with reference to FIG.

  First, a metal member 11 formed into a U-shape and an anode terminal 12 and an anode terminal 13 cut into a flat plate shape are prepared. As shown in FIG. 10, the two anode terminals 12 and 13 are made of metal. It arrange | positions at the both ends of the member 11. FIG. The metal member 11 at this time can be obtained by, for example, forming a single plate of metal such as copper into a desired shape by etching or a mold, and then bending the cross-sectional shape into a “U” shape. it can. The metal type of the metal member 11 is not limited to copper, and other metals may be used. At that time, it is possible to improve the characteristics of the high-frequency filter, which is the final product, by using a metal with high conductivity. However, the material can be selected in consideration of workability and cost. Thus, the effect of the present invention is not impaired.

  Next, alignment is performed such that the cathode part of the filter element 21 is placed on the metal member 11 and the anode parts at both ends of the filter element 21 are placed on the anode terminal 12 and the anode terminal 13. The terminal 12 and the anode terminal 13 are bonded to the filter element 21 with a conductive material 31. When adhering, the space between the filter element 21 and the metal member 11 is filled with the conductive material 31 evenly. Further, in the filter element 21, the cathode 211 is formed through the dielectric layer 213 so as to surround the anode 212, and thus the anode 212 and the cathode 211 are not on the same plane. Therefore, when the filter element 21 and the metal member 11 are bonded, the anode terminal 12 and the anode terminal 13 are floated with respect to the anode 212. Therefore, the connection element 51 as a spacer may be inserted between the anode 212 of the filter element 21 and the anode terminal 12 and the anode terminal 13 and then bonded. The connection element 51 may be a conductor. In addition, a conductive material may be used for connection of the anode 212, the connection element 51, the anode terminal 12 and the anode terminal 13 of the filter element 21 or may be connected by a method such as welding. If it can connect, the connection method in particular will not ask | require. A plurality of filter elements 21 are stacked in the same manner. As described above, the number of stacks is arbitrary, and only one may be used. The quantity of the filter elements 21 may be determined in consideration of the electrostatic capacity necessary for the high frequency filter 1 and the value of the direct current flowing through the anode. In FIG. 10, five filter elements 21 are stacked.

  After all the filter elements 21 are stacked, heat is applied to solidify the conductive material 31 and increase the conductivity. The heating temperature and time at this time are different depending on the conductive material used. For example, if a heat-solidified silver paste mainly composed of silver is used as an example, it can be heated at 150 ° C. for 20 minutes. Good. After the conductive material 31 is solidified, the whole is sealed with a protective resin 41. Resin sealing includes various methods such as transfer molding, casting, and potting, but the effectiveness of the present invention is not impaired by the difference in resin sealing. Further, when selecting a resin sealing method, it is desirable to select a sealing method that can ensure environmental resistance as a component and that can be automatically mounted when mounted on a printed circuit board or the like. . For example, when resin-sealing with an epoxy resin by a transfer mold method, heat treatment at 170 ° C. for about 2 hours may be applied in order to improve the strength of the resin 41 after sealing. Moreover, since it is necessary to expose the anode and the cathode to the outside of the resin 41 at the time of sealing, it is necessary to consider the shape of the metal member 11, the anode terminal 12, and the anode terminal 13 and the shape of the resin sealing. There is. In FIG. 10, the metal member 11, the anode terminal 12, and the anode terminal 13 are exposed on the lower surface after resin sealing, and the exposed portions are used as an anode and a cathode. At this time, when the exposed surface of the metal member 11 exposed on the lower surface is resin-sealed in a shape that is divided into two by resin, the high-frequency filter 1 having a four-terminal structure including two anodes and two cathodes, Become.

  In addition, in the said form, although the U-shaped metal member 11 was used, as above-mentioned, in order to have the intensity | strength with respect to curvature and to reduce an equivalent series resistance and an equivalent series inductance, the filter element part 20 It is sufficient that three or more surfaces are continuously surrounded by the metal member 11. From this, the cross-sectional shape of the metal member 11 does not need to be U-shaped, and can take various shapes as shown in FIG. FIG. 11 is a cross-sectional view showing an example of a high-frequency filter when the metal member 11 has a rectangular cylindrical shape. A high frequency filter 110 shown in FIG. 11 surrounds a filter element portion 120 formed by stacking a plurality (five) of filter elements 121 on four sides, and the filter element 121 and the metal member 11 are in contact with each other in a larger area. As compared with the three-surface contact type high frequency filter 1 shown in FIG. 1 and FIG. 2, the present invention has an excellent effect of preventing warpage and realizing a low equivalent series resistance and equivalent series inductance.

  Examples of utilization of the present invention include a power supply filter and a noise filter that are used by being mounted on a printed circuit board of a computer such as a personal computer or a workstation or an electronic device such as a mobile phone.

It is a typical permeation | transmission perspective view which shows an example of the high frequency filter of this invention. It is sectional drawing along the A-A 'line of FIG. It is a perspective view of the filter element which comprises a filter element part. It is sectional drawing which shows the example of the metal member applied to this invention. It is a graph of the high frequency filter characteristic when an equivalent series resistance changes. It is a graph of the high frequency filter characteristic when an equivalent series inductance changes. It is sectional drawing of the conventional high frequency filter. This is an equivalent circuit of a conventional high-frequency filter focusing on ESR and ESL. It is an equivalent circuit of the high frequency filter of the present invention focusing on ESR and ESL. It is a manufacturing method of the high frequency filter of the present invention. It is sectional drawing which shows the other form of the high frequency filter of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,110 High frequency filter 11,111 Metal member 12,13 Anode terminal 20,120 Filter element part 21,121 Filter element 211 Cathode 212 Anode 213 Dielectric layer 214 Electrode part 31,131 Conductive material 41,141 Protective resin 51 Connection element

Claims (6)

A filter element comprising an anode having a substantially flat plate shape, a dielectric layer formed so as to surround the anode, and a cathode provided so as to further surround the dielectric layer. the opposite ends Ri name by stacking a plurality of filter elements having an electrode portion made of the anode which projects from the dielectric layer, the filter element of said plurality of stacked by bonding the respective cathodes with an adhesive material, a filter element formed by perforated at both ends both ends anode portion electrically connected to the electrode portions in the plurality of filter elements,
A metal member surrounding at least three surfaces of the filter element portion so as to face each of the cathodes;
An adhesive conductive material filled between each of the cathodes and the metal member;
A first anode terminal and a second anode terminal electrically connected to the anode portions at both ends ,
The high frequency filter, wherein the metal member serves as a cathode of a high frequency filter, and the anode terminals serve as an anode of the high frequency filter.   The high frequency filter according to claim 1, wherein the metal member has a substantially U shape, and the filter element portion is accommodated therein.   The high frequency filter according to claim 1, wherein the metal member has a cylindrical shape, and the filter element portion is accommodated therein. The anode portions at both ends of the filter element portion are electrically connected via connection elements between electrode portions made of anodes protruding from both ends of the laminated filter elements. The high frequency filter in any one of Claims 1-3 . The metal member, the filter element portion, and the conductive material are sealed with a resin, and are an integrated structure in which one exposed portion from which the metal member is exposed and each anode terminal at both ends is exposed to 2 5. The high-frequency filter according to claim 1, wherein the high-frequency filter is an integral structure of a three-terminal structure having two exposed portions . The metal member, the filter element portion, and the conductive material are sealed with a resin, and the two exposed portions from which the metal member is exposed and the anode terminals at both ends are exposed to 2 5. The high-frequency filter according to claim 1, wherein the high-frequency filter is an integral structure of a four-terminal structure having two exposed portions .

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