JPH07105309B2 - Film capacitor and manufacturing method thereof - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film capacitor used in electronic equipment and electric equipment, and a manufacturing method thereof.

2. Description of the Related Art In recent years, there has been a strong demand for miniaturization, weight reduction, and chip formation of electronic components, and film capacitors have also been actively developed for miniaturization, weight reduction, and chip formation.

The following means can be mentioned as a method of miniaturizing the film capacitor from the viewpoint of the structure.

(1) Thin the film used as a dielectric.

(2) Thin the electrode.

(3) The part that does not contribute to the capacitance is reduced.

Regarding the method (1), it is clear that the relationship between the capacitance C of the capacitor, the thickness d of the dielectric, the relative permittivity ε, and the facing area S of the electrodes is expressed by C = ε · S / d. Like
Thinning the dielectric is a very effective method for miniaturization because it reduces the shape of the capacitor and increases the capacitance. Therefore, at present, a polyethylene terephthalate film having a thickness of 1 μm is commercially available as a dielectric for a film capacitor.

Regarding the method (2), there is a method of using a metal layer having a thickness of several hundred liters formed on a film by a vacuum deposition method or the like as an electrode, which is a very effective means for downsizing a film capacitor. This type of film capacitor is called a metallized film capacitor.

In the method (3), the portion that does not contribute to the capacitance is a portion excluding the opposing electrodes and the dielectric portion located between them. For example, a part of the other electrode without facing electrodes, a dielectric portion protruding from between the facing electrodes, and an end face electrode for quoting the electrodes from electrodes having polarities different from each other. These are the parts necessary for surely pulling out the electrodes to the outside. Others include protective films, exterior parts, and lead wires.

In addition to the method of studying miniaturization from such a structural aspect,
It is also possible to consider the characteristics of the constituent material of the film capacitor itself. As an example, there is a case where the dielectric constant of the dielectric film is increased. Since this method is outside the scope of the present invention, the above description will be omitted.

From the above, it can be seen that in order to miniaturize the film capacitor, it is sufficient to manufacture the film capacitor by using a thin and metallized film while reducing the portion that does not contribute to the capacitance.

However, when a thin dielectric film is used, it is extremely difficult to draw the electrode from the electrode to the end face electrode due to the construction method. The reason will be described with reference to the drawings.

In FIG. 6 (A), 61a and 61b are metallized films,
The electrodes 62a and 62b are formed of films 63a and 6 made of an organic material, respectively.
It is configured by being formed on 3b by a vacuum deposition method or the like.

64a and 64b are end face electrodes, and electrode lead-out end faces 65a and 65b, respectively.
It is formed by a metal spraying method or the like.

The connection state (hereinafter referred to as a contact) between the electrodes 62a and 62b and the end surface electrodes 64a and 64b depends on the capacitor characteristics and reliability.
This is one of the most important factors.

As shown in FIG. 6B, the contacts are weak when only the side end faces of the electrodes 62a and 62b are connected to the end face electrodes 64a and 64b. That is, since the current flowing when the capacitor is charged or discharged has to pass through an extremely small cross-sectional area of the connection portion, the resistance at this portion is high, Joule heat is generated, and the contact is likely to come off. If the contact comes off, the dielectric loss tangent characteristic of the capacitor is extremely deteriorated, and the capacitance is reduced.

In order to solve this problem, as shown in FIG. 6 (A), the end face electrodes 64a, 64b are connected not only to the side end faces of the electrodes 62a, 62b, but also to portions 66a, 66b of the main faces thereof. Have to be in a state of being.

The following methods are available to enable such connection.

(A) As shown in FIG. 6 (A), films 63a, 63b
Move the position of the side end face of. And this shift amount B, B ′
The end surface electrodes 64a and 64b are caused to enter the gap 67 generated by the above and are connected to a part of the main surfaces of the electrodes 62a and 62b.

(B) As shown in FIG. 7 (A), films 63a, 63b
A notched portion 68 is provided at a side end portion of the end face electrode, and the end face electrode is inserted into a gap 69 formed by this portion 68 to be connected to a part of the main surfaces of the electrodes 62a and 62b.

(C) As shown in FIG. 7 (B), films 63a, 63b
A deformed portion (hereinafter referred to as embossing) 70 having unevenness in the thickness direction is provided at the side end portion of the end surface electrode, and the end surface electrode is inserted into a gap 71 created by the embossing 70 to connect with a part of the main surface of the electrodes 62a, 62b. Let

However, from the viewpoint of miniaturization of capacitors, these methods all have a factor that hinders miniaturization. Good contact cannot be ensured unless the above-mentioned offset portion, chip, and emboss are provided with a certain size. This is because, in order to accurately match the positions of the shift, the chip or the emboss in the laminating process or the winding process of the metallized film, they must be made to have a certain size. Usually, the sizes of the “shift”, “notch”, and “emboss” are at least 0.1 mm or more, preferably 0.2 mm or more in the width direction of the film. These are the parts that do not contribute to the capacitance and it is necessary to occupy a considerably large volume in order to obtain a good contact in the capacitor. Therefore, the above method is extremely difficult to downsize the capacitor. To do.

Next, the method will be considered in terms of mass productivity. As a method with high mass productivity, as shown in FIG. 2 (A), a non-metallized portion 7a extending in the length direction of the film is formed so that a plurality of capacitor elements can be formed on the wide metallized films 1a and 1b. , 7b
There is a method (hereinafter referred to as a wide width method) in which a plurality of strips are provided, and these are laminated or wound and then cut into individual capacitor elements.

In the method (a) described above, since the offset portion cannot be formed using the wide width method, the capacitor elements must be formed one by one. On the other hand, according to the methods (b) and (c), since the wide construction method can be used, mass productivity is high.

Recently, there has been proposed a method of chemically and selectively removing a cross-section of an electrode to expose an end face of the electrode and connecting the end face electrode. Since this method can use a wide width method,
Excellent mass productivity. Moreover, the selective removal of the film for obtaining the contact is performed after the films are laminated or wound, so that the film can be removed accurately with a very narrow width. Therefore, the method is very excellent in terms of downsizing. Further, as shown in FIG. 5, since the surface portions of the vapor deposition electrodes 2a and 2b are connected to the end face electrodes 4a and 4b, electrically necessary contacts can be obtained.

However, a chip-type metallized film capacitor is manufactured using the above-mentioned method, and is surface-mounted on a printed circuit board, and the "bending flexure test" is specified in RC-3402 of EIAJ.
(If the standard is applied to a chip type monolithic ceramic capacitor, but there is no equivalent standard for a film capacitor, the standard is used instead.) The contact may come off and the dielectric loss tangent characteristic may become poor.

Further, as shown in FIG. 8, when the capacitor 81 manufactured by the above method is used as the base 81 and the capacitor 81 is cut by the rotary blade 82 to obtain the individual capacitor elements 83, the mechanical properties at the time of cutting are The dielectric loss tangent characteristic may be deteriorated due to stress.

Furthermore, when a lead wire is welded to the end face electrode, the dielectric loss tangent characteristic may become poor after welding.

Although the contacts produced by the above-mentioned method have electrical requirements, they have weak adhesion at the end faces and are liable to break because the vapor deposition electrodes are weak against various mechanical stresses on the contact parts. It turned out to be the cause.

The present invention is to solve the above-mentioned conventional problems, even if it is a vapor deposition electrode, it does not cause mechanical stress and disconnection, it is possible to maintain a good connection state between the electrode and the end surface electrode, An object of the present invention is to provide a small-sized film capacitor that is resistant to static stress and a method that can be manufactured with high mass productivity.

Means for Solving the Problems The film capacitor of the present invention comprises a plurality of electrodes, a dielectric film made of an organic material arranged between the plurality of electrodes, and an electrode lead end face which is provided with the electrodes and alternates with the electrodes. And an end face electrode connected to the electrode, and a gap is formed between the electrode and the dielectric film or at least one of the dielectric films in the electrode lead-out end face portion by the electrode or the dielectric film being turned over. At least a part of the end face electrode is inserted into this gap.

Further, the film capacitor manufacturing method of the present invention is directed to an electrode lead-out end face portion of a laminated body or a wound body composed of a plurality of electrodes and a dielectric film made of an organic material arranged between the plurality of electrodes. A step of forming a gap between the electrode and the dielectric film or between the dielectric films by turning the electrode or the dielectric film, and a portion of the dielectric film on the electrode lead-out end face side. The method includes a step of bringing the surface exposed in the gap into contact with a reactive gas to selectively remove it, and a step of forming an end face electrode on the electrode lead-out end face.

Further, by cutting a laminated body or a wound body having a plurality of capacitor elements with a blade at a position which becomes an electrode drawing end face of each capacitor element, between the electrodes and the dielectric film or between the dielectric films. The method includes a step of forming a gap by turning the electrode or the dielectric film on at least one side.

Action With the above-described structure, in the film capacitor of the present invention, at least a part of the end face electrode penetrates into the gap between the metallized films or the selectively removed portion of the dielectric film. Improves adhesion to the body. Therefore, the vapor deposition electrode does not break even when mechanical stress is applied, and the contact is maintained in a good condition even when subjected to cutting, welding, bending flexure test, etc. in which mechanical stress is applied.

Further, in the method of manufacturing a film capacitor of the present invention, when the wound body or the laminated body is cut at the electrode lead-out end face position of each capacitor element, it is distorted because of the blade, and the electrode and the dielectric film end face position between layers are distorted. A gap is formed by turning over, and a part of the dielectric film exposed in the gap formed by cutting with the electrode lead-out end face side of the dielectric film is selectively removed to form the gap thereafter. The end face electrode firmly adheres to the wound body or the laminated body, and good contact can be obtained.

Examples Hereinafter, one example of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of the laminated film capacitor in this embodiment.

In the figure, 1a and 1b are single-sided metallized films, and electrodes 2a and 2b
Is a dielectric film made of organic material (hereinafter referred to as film) 3
It is formed on a and 3b by the vacuum deposition method. Four
a and 4b are end face electrodes formed by the metal spraying method, a part of which is 5
Between the electrodes 2a, 2b and the films 3a, 3b, or the film
It is difficult to get between 3a and 3b.

Since the portions 5 of the end face electrodes 4a, 4b are embedded in the interlayer as described above, the adhesive force between the laminate of the single-sided metallized films 1a, 1b and the end face electrodes 4a, 4b is very strong.

6a and 6b are protrusions of the electrodes 2a and 2b, respectively, and are formed on the film 3
The electrodes 2a, 2b are formed by selectively removing the electrode lead-out end face side portions of a and 3b as described later.
b is connected to the end face electrodes 4a and 4b at these protruding portions 6a and 6b. In this connection state, since the end surface electrodes 4a, 4b are connected to the surfaces of the electrodes 2a, 2b, a very good contact can be obtained.

Specific examples will be described below.

Aluminum is vacuum-deposited on the polyethylene terephthalate film 3a, 3b having a thickness of 2 μm to be a dielectric and the thickness is 5
00Å electrodes 2a, 2b are formed, and single-sided metallized films 1a, 1b
Was produced. Then, on the single-sided metallized films 1a and 1b, a plurality of unmetallized portions extending in the film length direction were provided by a masking method.

These single-sided metallized films 1a and 1b are overlapped with the nonmetallized portion 7 displaced, and wound on a flat bobbin 8 as shown in FIG. 2 (A) and pressed with heating,
The bobbin 8 was cut and separated to obtain a laminated body 9 having a plurality of capacitor elements as shown in FIG. 2 (B).

This laminated body 9 is cut with a sharp blade such as a razor at the electrode drawing end face positions A, A'of each capacitor element in the laminating direction to obtain the capacitor element 10 shown in FIG. 2 (C). Obtained. When using a razor etc., as can be seen from the figure, strain can be caused by the blade pressure and the electrodes 2a, 2b and the film 3a,
3b hangs and is cut. As a result of this cutting, a gap 12 is formed between the films 3a, 3b and the electrodes 2a, 2b or between the films 3a, 3b on the electrode lead-out end faces 11a, 11b of the capacitor element 10 due to the flipping of the electrodes or the dielectric film. Were formed in large numbers.

The electrode extraction end surfaces 11a, 11b and the gap 12 of the capacitor element 10 thus obtained are reacted with a highly reactive gas obtained by ionizing oxygen by a high frequency electric field, and a film electrode extraction end surface side portion, Part of the surfaces of the films 3a and 3b exposed in the gaps were selectively removed. The removal width of the film electrode extraction end face side is the original electrode extraction end face.
It was set to 0.05 mm from 11a and 11b.

By selectively removing the films 3a and 3b, the electrodes 2a and 2b have a protruding shape as shown by reference numerals 13a and 13b in FIG. 2 (D). After that, zinc is used as a metal spraying method to draw out the electrode end face 11a,
By spraying on 11b respectively, end face electrodes 4a and 4b were formed to obtain a capacitor element.

When the capacitor element thus obtained is cut and observed, as shown in FIG. 1, a part of the end face electrodes 4a, 4b is formed between the electrodes 2a, 2b and the films 3a, 3b, or the film 3a, A large number were inserted in a part of the electrode lead-out end face side between 3b. However, they did not reach the opposing electrodes.

As Comparative Example A, a laminate was prepared using the same single-sided metallized film, and cut by laser light at the electrode extraction end face position to prepare a gap-free capacitor element 10, which was subjected to the film selective removal step Was subjected to the same process as above to obtain a capacitor element.

When the obtained capacitor element of Comparative Example A was cut and observed, as shown in FIG. 5, between the electrodes 2a, 2b and the films 3a, 3b, or between the films 3a, 3b, the end face electrodes 4a, 4b were formed. Was not intervening.

As Comparative Example B, a laminate was prepared using the same single-sided metallized film, cut at the electrode extraction end face position, and then subjected to the step of directly forming the end face electrode without subjecting to the film selective removal step. A capacitor element was obtained.

As Comparative Example C, using a metallized film of the same thickness,
A capacitor element was manufactured by providing a shift of 2 mm.

The capacitors of the present invention obtained as described above and the capacitors of Comparative Examples A to C were subjected to the "bending deflection test" specified in RC-3402 of Japan Electronic Equipment Manufacturers Association (EIAJ). Further, the test was conducted with the number of flexural flexures set to 10 times. The number of samples was 10, and the dielectric loss tangent was measured at a frequency of 1 kHz before and after the test.

The results are shown in FIG.

As shown in FIG. 3, the film capacitor of the present invention is
No change in the dielectric loss tangent was observed even after 10 bending flexural tests, and it is clear that it can withstand the mechanical stress applied thereto.

On the other hand, in Comparative Example A, not only the dielectric loss tangent was greatly increased by the bending deflection test, but also its variation was large. In Comparative Example B, not only the dielectric loss tangent was already greatly varied in the initial state, but also the value was significantly increased by the flexural bending test, and the variation was also large. In Comparative Example C, the change of the dielectric loss tangent in the bending deflection test was very small as compared with those in Comparative Examples A and B, but it was recognized that there was a considerable variation in the bending deflection test as compared with the products of the present invention.

Further, the adhesive strength of the end face electrodes of the capacitor elements of the present invention and Comparative Examples A to C was subjected to a tensile test and tested by their breaking strength. The results are shown in FIG.

As shown in FIG. 4, the film capacitor of the present invention is
It can be seen that the adhesion force of the end face electrode is very strong and its variation is small.

On the other hand, in each of Comparative Examples A and B, the adhesion of the end face electrode is small. Comparative Example C has a larger adhesive force than those of Comparative Examples A and B, but the dispersion of the adhesive force is very large and the reliability is poor.

As described above, in the capacitor of the present invention, since a part of the end face electrode is inserted between the electrode and the film or between the films, the adhesive force of the end face electrode is strong, and therefore, against mechanical stress applied to the capacitor element. I understand that it is strong. Further, as compared with the conventional method of forming “shift”, “dent”, “emboss”, etc., since those portions which do not contribute to the electrostatic capacitance can be made smaller, the capacitor element can be miniaturized. Furthermore, since the wide winding method can be used, it is excellent in mass production.

In this example, polyethylene terephthalate was used as the dielectric, aluminum was vacuum-deposited as the electrodes, and zinc was metal-sprayed as the end face electrodes. The method of forming the end face electrode and the end face electrode is not limited to this, and a material used in a normal film capacitor or a method of forming the electrode and the end face electrode can be used.

Further, it goes without saying that the structure of the capacitor is not limited to the laminated type shown in this embodiment, and the same effect as described above can be obtained for the wound type.

Furthermore, the structure of the film is not limited to the single-sided metallized film shown in this example, and a double-sided metallized film or a composite film in which a dielectric is formed on at least one surface of the metallized film is also used. The same effect as can be obtained. Further, the present invention is not limited to the metallized film, and the same effect can be obtained even with a film capacitor using a foil electrode.

The method of selectively removing the film is not limited to this example, and for example, a gas in which fluorine or hydrogen is activated to increase the reactivity can be used.

EFFECTS OF THE INVENTION In the film capacitor of the present invention, at least a part of the end face electrode is formed between the electrode and the dielectric film or at least one of the dielectric films at the electrode lead-out end face part, and the gap due to the swelling is less likely to occur. Therefore, the adhesive force of the end face electrode can be improved, and therefore, the good connection state between the end face electrode and the electrode can be maintained even when subjected to mechanical stress. Therefore, it is possible to provide a small-sized film capacitor having high reliability against mechanical stress.

Further, in the method of manufacturing a film capacitor of the present invention, a gap can be provided between the electrode and the dielectric film or between the dielectric film and the dielectric film at the electrode extraction end face portion, and the film is exposed to the gap. Since the portion where the dielectric film is removed can be provided, the adhesion of the end face electrode is improved, and a small film capacitor that is highly reliable with respect to mechanical stress can be mass-produced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment of the film capacitor according to the present invention, and FIG. 2 is a view for explaining an example of the manufacturing method thereof. FIG. 1 (A) is a winding using a flat plate bobbin. FIG. 6B is a cross-sectional view of the laminated body separated from the plate-shaped bobbin, FIG. 7C is a sectional view showing a state in which the laminated body is cut, and FIG. Sectional drawing which shows the state which selectively removed the electrode drawing-out end surface part of a body, 3rd
FIG. 4 is a diagram showing the results of a flexural bending test performed on capacitors of the present invention and a comparative example in comparison, FIG. 4 is a diagram showing the adhesion strength of end face electrodes similarly, and FIG. 5 is a sectional view of a comparative example. FIG. 6 (A) is a cross-sectional view of a conventional example, FIG. 6 (B) is a cross-sectional view of another comparative example, and FIG. 7 (A) shows an example of a capacitor having a cutout portion at the film side end portion. FIG. 8 is a perspective view showing an example of a capacitor similarly provided with an emboss, and FIG. 8 is a perspective view showing a step of cutting a capacitor base material to obtain a capacitor element. 1a, 1b …… single-sided metallized film, 2a, 2b …… electrode, 3a, 3b
...... Dielectric film (film), 4a, 4b ...... End surface electrodes, 5 ...
… Part of the end face electrodes, 6a, 6b… Protruding parts of electrodes 2a, 2b.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location H01G 4/32 305 B 9174-5E (72) Inventor Minoru Kikuchi 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita (56) References JP 61-22612 (JP, A) JP 62-190828 (JP, A) JP 59-37564 (JP, B2)

Claims (3)

[Claims] 1. A plurality of electrodes, a dielectric film made of an organic material, which is disposed between the plurality of electrodes, and end face electrodes which are respectively provided on the electrode lead end faces and which are alternately connected to the electrodes. At least one of the electrode lead-out end face portion between the electrode and the dielectric film or between the dielectric films is provided with a gap due to the electrode or the dielectric film turning over, and at least the gap of the end face electrode is provided in this gap. A film capacitor with a part of it. 2. The electrode and the dielectric are provided at an electrode leading end face portion of a laminated body or a wound body composed of a plurality of electrodes and a dielectric film made of an organic material and arranged between the plurality of electrodes. A step of forming a gap between the body film and at least one of the dielectric films by turning the electrode or the dielectric film, and a portion of the dielectric film on the electrode lead-out end face side and a surface exposed in the gap. A method of manufacturing a film capacitor, comprising: a step of contacting with a reactive gas to selectively remove it; and a step of forming an end face electrode on the electrode lead-out end face. 3. A laminated body or a wound body, which comprises a plurality of electrodes and a dielectric film made of an organic material, which is arranged between the plurality of electrodes, and which has a plurality of capacitor elements. By cutting with a blade at a position that will be the electrode extraction end face of each capacitor element, a gap is formed between the electrode and the dielectric film or at least one of the dielectric films due to the flipping of the electrode or the dielectric film. A step of forming, a step of selectively removing an electrode lead-out end surface side portion of the dielectric film and a surface exposed in the gap by contact with a reactive gas, and a step of forming an end face electrode on the electrode lead-out end surface A method of manufacturing a film capacitor, comprising: