JP2011249707A - Metallized film capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metallized film capacitor capable of preventing an electric disconnection from occurring even when a load such as thermal shock is applied.SOLUTION: A metallized film capacitor 10 has a capacitor element 20 obtained by winding a metallized film with a vapor deposition electrode consisting of a metal vapor deposition film on at least one side of a dielectric film, and a metallikon part (metallikon layer 21) formed on a winding edge face of the metallized film. The metallikon part has a first, second, and third metallikon layers 21A, 21B, and 21C sequentially formed on a winding edge face 25A of the metallized film. The median particle diameter of metallikon particles forming the second metallikon layer 21B is larger than the median particle diameter of metallikon particles forming the first metallikon layer 21A contacting with the winding edge face, and smaller than the median particle diameter of metallikon particles forming the third metallikon layer 21C.

Description

  The present invention relates to a metallized film capacitor, and more particularly to a metallized film capacitor used for smoothing an inverter circuit for industrial equipment or automobiles.

  Conventionally, metallized plastic films have been used for metallized film capacitors. In this metallized plastic film, a metal thin film is formed by vapor-depositing a metal such as aluminum on a plastic film as a dielectric, and this metal thin film constitutes an internal electrode of the metallized film capacitor.

In the manufacturing process of a metallized film capacitor, a capacitor element is formed by winding this metallized plastic film, and metal is formed on both end faces of the capacitor element (both winding end faces formed by winding the metallized plastic film). A metallicon layer is formed by welding the particles.
A terminal plate is soldered to the metallicon layer, and a capacitor element to which the terminal plate is soldered is placed in an outer case, and a resin material such as an epoxy resin is filled and cured. A metallized film capacitor is manufactured by such a manufacturing process.

  In the metallized film capacitor having the above configuration, a metallicon layer is formed on both winding end faces of the metallized plastic film, and a terminal plate is soldered to the outside of the metallicon layer, and these are entirely covered with a resin material. It has become. That is, the metallicon layer is configured to be sandwiched between the winding end surface of the metallized plastic film and the resin material.

  As a structure of a metallized film capacitor for the purpose of improving the physical strength of a metallized electrode, two types of metallized layers made of different materials are formed on a winding end surface of a metallized plastic film (Patent Document 1). See)).

  Also, metallized film capacitors (patented with metallized electrode layers, conductive paste layers, solder layers) of different materials on the winding end surface of metallized plastic films for the purpose of improving moisture resistance and heat resistance. Reference 2) is considered. In this configuration, a layer is formed on the winding end surface of the metallized plastic film by a material capable of improving moisture resistance and heat resistance.

JP-A-11-204368 Japanese Patent Laid-Open No. 11-150038

  However, in a metallized film capacitor, there is a difference in coefficient of linear expansion between a resin material such as an epoxy resin covering the capacitor element and a plastic film (PP (polypropylene) film, etc.) constituting the metallized plastic film. When a thermal shock is applied to the capacitor element having the above configuration, a stress is generated between the resin material and the metallized plastic film.

  Due to this stress, peeling occurs in the metallicon layer, and the capacitor element is brought into an electrical disconnection state due to this peeling, resulting in a decrease in performance such that the dielectric loss tangent increases and the capacitance decreases.

  In view of the above problems, an object of the present invention is to provide a metallized film capacitor that can prevent electrical disconnection from occurring even when a load such as thermal shock is applied.

  The metallized film capacitor of the present invention is provided on a capacitor element formed by winding a metallized film provided with a vapor deposition electrode made of a metal vapor deposited film on at least one side of a dielectric film, and on a winding end surface of the metallized film. A metallized film capacitor having a metallized part, the metallized part having first, second and third metallized layers sequentially formed on a winding end surface of the metallized film, and a second metallized layer The central particle diameter of the metallicon particles that form the first metallicon layer that is in contact with the winding end face is larger than the central particle diameter of the metallicon particles that form the third metallicon layer, Is also small.

  According to this configuration, the first metallicon layer formed of the metallicon particles having a small particle size with good adhesion to the metallized plastic film, and the metallicon particles having a large particle size with good heat insulation and good mechanical load absorption. Since the second metallicon layer formed of metallicon particles having an intermediate particle size is interposed between the third metallicon layer formed in step 1, the level difference in the metallicon particle size is reduced. It is relieved and peeling in the metallicon layer can be prevented.

  With the above configuration, it is possible to realize a metallized film capacitor that has good adhesion to the winding end surface of the metallized plastic film, and that has good heat insulation and mechanical load absorption.

  In the metallized film capacitor, the fourth metallicon layer is formed outside the third metallicon layer, and the melting point of the metal of the fourth metallicon layer is lower than the melting point of the metal of the third metallicon layer. The center particle diameter of the metallicon particles forming the fourth metallicon layer may be smaller than the center particle diameter of the metallicon particles forming the third metallicon layer.

  Further, in the metallized film capacitor described above, the particle size distribution region of the metallicon particles forming the first metallicon layer and the particle size distribution region of the metallicon particles forming the second metallicon layer overlap, It is preferable that the particle size distribution region of the metallicon particles forming the metallicon layer and the particle size distribution region of the metallicon particles forming the third metallicon layer overlap.

  According to the metallized film capacitor of the present invention, it is possible to provide a metallized film capacitor that can prevent electrical disconnection from occurring even when a load such as thermal shock is applied.

It is sectional drawing which shows the metallized film capacitor by this invention. It is a perspective view with which it uses for description of the manufacturing method of the capacitor | condenser element by this invention. It is a perspective view which shows the capacitor | condenser element by this invention. It is the elements on larger scale which show the connection part of the winding end surface of a metallized plastic film, a metallicon layer, and a terminal copper plate. It is a graph which shows the particle size distribution of the metallicon particle | grains which form each metallicon layer. It is a flowchart which shows the manufacturing process of a metallized film capacitor. It is the elements on larger scale which show a comparative example. It is the elements on larger scale which show a comparative example. It is the elements on larger scale which show a comparative example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing an overall configuration of a metallized film capacitor 10 according to the present embodiment. As shown in FIG. 1, in the metallized film capacitor 10, a plurality of capacitor elements 20 are arranged inside an outer case 11, and a metallicon layer (metallicon part) 21 formed on both end faces of the plurality of capacitor elements 20. The terminal board 15 is soldered to the board. The outer case 11 is filled with a resin material 17 such as an epoxy resin and cured.

The plurality of capacitor elements 20 in the outer case 11 have the same configuration. FIG. 2 is a perspective view for explaining a method for manufacturing the capacitor element 20.
As shown in FIG. 2, a metallized plastic film 25 formed by forming a metal thin film 27 by depositing aluminum metal on a plastic film (PP (polypropylene) film or the like) 26 as a dielectric is produced. A plurality of metallized plastic films 25 are used, and these metallized plastic films 25 are wound while being shifted from each other in the width direction (FIG. 2A).
Then, the capacitor element 20 is obtained by winding the seal film 23 around the outermost package (FIG. 2B). On the winding end surface 25A of the metallized plastic film 25, a metallicon layer 21 made of metal particles (metallicon particles) is formed in a later step.

By heat-pressing the capacitor element 20 around which the metallized plastic film 25 is wound, an oblong-shaped capacitor element 20 having a predetermined thickness as shown in FIG. 3 is obtained.
Metallicon layers 21 are formed on both end faces of the capacitor element 20 (winding end faces of the metallized plastic film (FIG. 2)), and the terminal plate 15 (FIG. 1) is soldered to the metallicon layers 21.

  FIG. 4 is a partially enlarged view showing a connection portion of the winding end surface 25A of the metallized plastic film 25, the metallicon layer 21 and the terminal plate 15 in the capacitor element 20. 4 shows only a part of the winding end face 25A of the metallized plastic film 25. For example, the seal film 23 (FIG. 2) wound around the outermost package of the wound metallized plastic film 25 is shown. 3) and the like are omitted.

As shown in FIG. 4, on the winding end surface 25A of the metallized plastic film 25, the first metallicon layer 21A, the second metallicon layer 21B, and the third metallicon layer 21B are formed from the inner layer side of the capacitor element 20 toward the outer layer side. A metallicon layer 21C is sequentially formed. The first metallicon layer 21A is a layer in contact with the winding end surface 25A, and among the three layers (first to third metallicon layers 21A to 21C), a plurality of first metallicons having the smallest central particle diameter. It is formed by the particles 22A.
The second metallicon layer 21B is formed of a plurality of second metallicon particles 22B having a center particle diameter larger than the particle diameter of the first metallicon particles 22A forming the first metallicon layer 21A.
The third metallicon layer 21C is formed of a plurality of third metallicon particles 22C having a center particle diameter larger than the particle diameter of the second metallicon particles 22B forming the second metallicon layer 21B.

  The terminal copper plate 15 is soldered to the outside of the third metallicon layer 21C with solder 18, and the resin material 17 is filled to the outside of the terminal copper plate 15.

  Thus, between the winding end surface 25A formed by winding the metallized plastic film 25 and the resin material 17, from the winding end surface 25A of the metallized plastic film 25, the outer layer side (resin material 17 side). A plurality of metallicon layers 21A, 21B, and 21C having a gradually increasing central particle diameter are sequentially formed.

FIG. 5 is a graph showing the particle size distribution of the metallicon particles forming each metallicon layer (first to third metallicon layers 21A to 21C).
In the case of the present embodiment, the particle diameter of the first metallicon particle 22A forming the first metallicon layer 21A (hereinafter, the particle diameter means the particle diameter measured by the following method) is 1 to 100 μm (center) The particle diameter of the second metallicon particle 22B forming the second metallicon layer 21B is 10 to 150 μm (the center particle diameter is 100 μm), and the third metallicon layer 21C is The particle diameter of the third metallicon particles 22C to be formed is 50 to 250 μm (the center particle diameter is 150 μm). Here, the above-mentioned central particle diameter is called 50% particle diameter or median diameter.
In addition, the measurement of the particle diameter and particle diameter distribution of said particle | grain was performed with the following apparatus and conditions.
・ Measurement equipment: KEYENCE microscope (VH-8000)
Measurement conditions: Magnification 175 times 100 metallicon particles in a range not sprayed to a uniform thickness were randomly measured by spraying squarely on cardboard under each metallicon spraying condition.

Each metallicon layer 21A, 21B and 21C is obtained by melting a metal-based material including aluminum, tin, zinc, copper, antimony, solder-based alloy, etc., and spraying it on the surface of the object to obtain a metal coating layer. It is formed using a method (metal spraying method). Here, the same zinc-based material was used for each of the metallicon layers 21A, 21B, and 21C.
The particle diameters of the metallicon particles 22A, 22B, and 22C can be controlled by the thermal spraying conditions of the metallicon particles when forming the metallicon layers 21A to 21C. For example, it can be controlled by changing the spraying distance, the air pressure, the amount of wire, and the like.

  In the case of the present embodiment, as the conditions for forming the first metallicon layer 21A, the spraying distance of the metallicon particles is 100 mm, the air pressure is 0.5 Mpa, and the amount of wire (the amount of wire used per minute) is 13 g / min. As the conditions for forming the second metallicon layer 21B, the metallicon particle spraying distance is 100 mm, the air pressure is 0.3 Mpa, the wire amount is 26 g / min, and the conditions for forming the third metallicon layer 21C are as follows: The spraying distance of the particles is 250 mm, the air pressure is 0.3 Mpa, and the wire amount is 40 g / min. Thereby, the metallicon layers 21A to 21C can be formed with the particle size distribution shown in FIG.

  In addition, as conditions for forming the metallicon particles, the particle diameter can be increased (roughened) by increasing the spraying distance of the metallicon particles, decreasing the air pressure, or increasing the amount of the wire.

As shown in FIG. 4, in the first metallicon layer 21 </ b> A, by forming the first metallicon layer 21 </ b> A with the first metallicon particles 22 </ b> A having a size that can enter the gaps between the layers of the metallized plastic film 25, The adhesion strength between the first metallicon layer 21A and the winding end surface 25A of the metallized plastic film 25 can be increased.
At the same time, in the third metallicon layer 21C, the metallicon having the largest particle diameter is used to provide a function of a heat insulating layer for insulating heat of soldering of the terminal copper plate 15 and a function for absorbing a mechanical load. A third metallicon layer 21C is formed by the particles 22C.
Between these, the metallicon particles 22B having a particle diameter intermediate between the particle diameter of the metallicon particles 22A forming the first metallicon layer 21A and the particle diameter of the metallicon particles 22C forming the third metallicon layer 21C are used. 2 metallicon layers 21B are formed.
With the above-described configuration, the particle diameters of the adjacent metallicon particles 22A to 22C of the respective metallicon layers 21A to 21C can be made close to each other, and the adhesion strength between the respective layers can be maintained.

In addition, the particle size distribution region of the metallicon particles 22A forming the first metallicon layer 21A and the particle size distribution region of the metallicon particles 22B forming the second metallicon layer 21B overlap to form the second metallicon layer 21B. The particle size distribution region of the metallicon particles 22B to be overlapped with the particle size distribution region of the metallicon particles 22C forming the third metallicon layer 21C.
Thus, for each metallicon layer, by setting the distribution of the particle size ranges of adjacent metallicon layers to overlap, metallicon particles having relatively close particle sizes coexist in two adjacent metallicon layers. The adhesion strength between the layers can be maintained.

  FIG. 6 is a flowchart showing a manufacturing process of the metallized film capacitor 10 of the present embodiment. As shown in FIG. 6, first, a metallized plastic film 25 (FIG. 2) formed by forming a metal thin film 27 (FIG. 2) by depositing aluminum metal on the plastic film 26 is produced (S11). A sheet of the metallized plastic film 25 is wound, and the sealing film 23 is wound around the outermost package and stopped (S12).

  Next, what wound the metallized plastic film 25 is heat-pressed and made into an oval shape (S13). A first metallicon layer 21A is formed on the winding end surface 25A of the oval metallized plastic film 25 (S14), and a second metallicon layer 21B is formed on the first metallicon layer 21A. (S15) Further, a third metallicon layer 21C is formed on the second metallicon layer 21B (S16).

  The capacitor elements 20 thus formed with the three metallicon layers are arranged in the outer case 11 (FIG. 1), and the terminal copper plate 15 is soldered to the outermost metallicon layer (third metallicon layer 21C) ( S17). And the metallized film capacitor 10 is completed by filling the exterior case 11 with the resin material 17 (S18).

  As described above, in the present embodiment, the particle diameters of the metallicon particles 22A to 22C forming the respective layers from the first metallicon layer 21A to the third metallicon layer 21C are sequentially increased for each layer. In the first metallicon layer 21A that is formed and is in contact with the winding end surface 25A of the metallized plastic film 25, the metallicon particles 22A having a particle size of a size that can enter even a slight gap between the respective layers of the metallized plastic film 25. Is used. Thereby, the adhesion strength between the first metallicon layer 21A and the winding end face 25A of the metallized plastic film 25 is improved.

As a comparative example, as shown in FIG. 7, when the metallicon layer 21 is formed using only the metallicon particles 22 </ b> C having a particle size that is difficult to enter the gaps between the layers of the metallized plastic film 25 (FIG. 7 ( A)) Once the metallicon layer 21 is formed, adhesion between the metallicon layer 21 and the metallized plastic film 25 is reduced due to the small number of metallicon particles 22C entering the gaps between the layers of the metallized plastic film 25. The strength is weakened.
Therefore, when a load such as a thermal shock is applied, the metallicon layer 21 may be peeled between the metallicon layer 21 and the metallized plastic film 25 as shown in FIG. 7B. . When this peeling occurs, the metallicon layer 21 and the metallized plastic film 25 are electrically disconnected, and the characteristics of the capacitor element 20 are deteriorated.

On the other hand, in the capacitor element 20 used in the metallized film capacitor 10 of the present embodiment shown in FIG. 4, the particle diameter of the metallicon particles 22A forming the first metallicon layer 21A is a metallized plastic film. 25 is formed in a size that can enter the gaps between the respective layers, so that more metallicon particles 22A enter the gaps between the respective layers, and the adhesion strength between the first metallicon layer 21A and the metallized plastic film 25 is increased. Can be increased.
Thereby, even if a load such as a thermal shock is applied, it is possible to prevent the separation of the metallicon layer 21 between the first metallicon layer 21A and the metallized plastic film 25.

Further, as shown in FIG. 8 as a comparative example, when the entire metallicon layer 21 is formed by only the metallicon particles 22A having a size that can enter the gaps between the respective layers of the metallized plastic film 25, the metallicon layer 21 as a whole is As the particle diameter of the metallicon particles 22A forming the layer 21 is small, the voids between the particles are reduced, and the air contained in the voids is reduced. Thereby, the heat insulation effect in the metallicon layer 21 is lowered, and when the terminal copper plate 15 is soldered by the solder 18, the soldering heat is easily transmitted to the metallized plastic film 25.
As a result, the metallized plastic film 25 is shrunk by heat, whereby a stress is generated between the metallicon layer 21 and the metallized plastic film 25, thereby generating a gap AR11 (FIG. 8A).
When the capacitor element 20 is in such a state, as shown in FIG. 8B, when a load such as a thermal shock is applied to the capacitor element 20, a gap between the metallicon layer 21 and the metallized plastic film 25 is obtained. There is a possibility that peeling of the metallicon layer 21 may occur in the gap AR11. When this peeling occurs, the metallicon layer 21 and the metallized plastic film 25 are electrically disconnected, so that the characteristics of the capacitor element 20 are deteriorated.

  In addition, when the entire metallicon layer 21 is formed of the metallicon particles 22A having a small particle diameter, the impact absorbability is also inferior, and peeling as shown in FIG. Become.

On the other hand, in the capacitor element 20 of the present embodiment shown in FIG. 4, the first metallicon layer 21A is formed by the first metallicon particles 22A having a size that can enter the gaps between the layers of the metallized plastic film 25. By doing so, the adhesion strength between the metallicon layer 21 and the metallized plastic film 25 can be secured.
At the same time, by forming the second metallicon layer 21B and the third metallicon layer 21C by the second metallicon particle 22B and the third metallicon particle 22C having a larger central particle diameter than that, the metallicon layer 21 as a whole, Compared with the case where all are formed by the first metallicon particles 22A having a small particle diameter, the voids between the particles can be increased, thereby increasing the amount of air contained in the voids and increasing the heat insulating effect. be able to.

  Further, in addition to the metallicon particles 22A having a small central particle diameter, the metallicon layer 21 is formed by the metallicon particles 22B and 22C having a large central particle diameter, so that the impact absorption can be improved as a whole of the metallicon layer 21. It can sufficiently withstand mechanical loads.

Further, as shown in FIG. 9 as a comparative example, metallicon particles 22A having a size that can enter the gaps between the respective layers of the metallized plastic film 25, and metallicon particles 22C having a size that can increase the gap between the particles in order to enhance the heat insulation effect. Thus, when the two metallicon layers 21A and 21C are formed (FIG. 9A), the level difference in the center particle diameter of the metallicon particles 22A and 22C becomes too large, and the adhesion effect between the metallicon particles becomes low.
As a result, as shown in FIG. 9B, when a load such as a thermal shock is applied, the metallicon layers 21A and 21C may be peeled between the metallicon particles (between the two metallicon layers 21A and 21C). There is. When this peeling occurs, the characteristics of the capacitor element 20 are degraded due to an electrical disconnection between the metallicon layers 21A and 21C.

On the other hand, in the capacitor element 20 of the present embodiment shown in FIG. 4, the center particle diameter gradually increases from the first metallicon layer 21A to the second and third metallicon layers 21B and 21C. By using the second and third metallicon particles 22B and 22C, it is possible to avoid the metallicon particles 22A and 22C having a large difference in the center particle diameter from being adjacent to each other in the metallicon layer 21.
Thereby, while preventing generation | occurrence | production of peeling between the metallicon particles by the level difference of the particle diameter between the metallicon particles which mutually contact, as the whole metallicon layer 21, the space | gap between metallicon particles is enlarged and the heat insulation effect is improved. be able to.

In the above-described embodiment, the case where the center particle diameter of the metallicon particles forming the third metallicon layer 21C, which is the outermost layer, is maximized has been described. Further, the outer side of the third metallicon layer 21C ( The fourth metallicon layer may be formed on the outermost layer with metallicon particles having good solderability. For example, a metal having a melting point lower than that of the third metallicon metal may be used.
In this case, since the third metallicon layer 21C has a heat insulating function and a mechanical load absorbing function, the central particle diameter of the fourth metallicon layer is larger than the particle diameter of the third metallicon layer 21C. Can be small.

  In the above-described embodiment, the case where the metallicon layer 21 is formed by the particle size distribution shown in FIG. 5 is described. However, the present invention is not limited to this, and the first to third metallicon layers 21A to 21C. If the metallicon particles having a large central particle diameter are sequentially used, the same effects as those described above can be obtained.

  In the above-described embodiment, the case where the metallicon layer is formed by three layers or four layers has been described. However, the present invention is not limited to this, and in short, the winding end surface 25A of the metallized plastic film 25 is used. When the first to third metallicon layers are formed, a plurality of layers having a large central particle diameter of the metallicon particles may be sequentially formed, and five or more layers may be provided.

In the above embodiment, the same material based on zinc is used for each of the metallicon layers 21A, 21B, and 21C. However, it is not always necessary to use the same material, and different materials are used for the metallicon layers 21A, 21B, and 21C. It can also be used.
As the metallicon material, a metal material including aluminum, tin, zinc, copper, antimony, solder alloy, or the like can be appropriately selected and used.

DESCRIPTION OF SYMBOLS 10 Metallized film capacitor | condenser 11 Exterior case 15 Terminal board 17 Resin material 18 Solder 20 Capacitor element 21 Metallicon layer 21A 1st metallicon layer 21B 2nd metallicon layer 21C 3rd metallicon layer 22A-22C Metallicon particle 23 Seal film 25 Metal Plastic film 25A winding end face 26 plastic film 27 metal thin film

Claims (3)

A metallized film having a capacitor element formed by winding a metallized film provided with a vapor deposition electrode made of a metal vapor deposited film on at least one surface of the dielectric film, and a metallized part provided on a winding end surface of the metallized film A capacitor,
The metallicon part has first, second, and third metallicon layers sequentially formed on the winding end surface of the metallized film, and the central particle diameter of the metallicon particles forming the second metallicon layer Is larger than the central particle diameter of the metallicon particles forming the first metallicon layer in contact with the winding end face and smaller than the central particle diameter of the metallicon particles forming the third metallicon layer. Metalized film capacitor to be used. A fourth metallicon layer is formed outside the third metallicon layer;
The melting point of the metal of the fourth metallicon layer is lower than the melting point of the metal of the third metallicon layer;
2. The metallized film according to claim 1, wherein a central particle diameter of the metallicon particles forming the fourth metallicon layer is smaller than a central particle diameter of the metallicon particles forming the third metallicon layer. Capacitor.   A particle size distribution region of the metallicon particles forming the first metallicon layer and a particle size distribution region of the metallicon particles forming the second metallicon layer are overlapped to form the second metallicon layer. 3. The metallized film capacitor according to claim 1, wherein a particle size distribution region and a particle size distribution region of the metallicon particles forming the third metallicon layer overlap each other.

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