JPH05121266A - Film capacitor - Google Patents

Abstract

PURPOSE:To provide a film capacitor having excellent reliability and characteristics for electronic component to be used for a variety of electronic and electric apparatus. CONSTITUTION:This capacitor has a metallic external electrode 3 containing oxidation-suppressed metal layer resulting from flame spraying of a Cu alloy containing 0.1-10wt.% of P, and this metallicon external electrode 3 and lead wires 4 are connected via an Sn-Pb alloy solder 5. This process can suppress oxidation of the surface of a metal particle during flame spraying and make a marked improvement in connection strength of a metallicon external electrode and lead wires via a solder such as an Sn-Pb alloy. Further, a high-reliability film capacitor is obtained and is hard to undergo electrocorrosion because of use of Cu alloy metallicons and further has moisture characteristics more faborable than those of a prior art film capacitor to enable omission of resin impregnation and encapsulation for lead holding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film capacitor, and more particularly to a film capacitor having improved moisture resistance and improved mechanical strength between an external electrode and a lead wire by thermal spraying.

[0002]

2. Description of the Related Art Recently, market needs for improved moisture resistance and high reliability for film capacitors have been escalated year by year, and it has become impossible to commercialize them by ignoring them. The transition from the conventional guarantee of humidity resistance in a 40 ° C-95% RH atmosphere to a guarantee of humidity resistance in a 60 ° C-95% RH atmosphere, and further 85 ° C-95% RH or -8
Guaranteed humidity resistance under 5% RH atmosphere, 121 ℃ -95% R
Requirement of moisture resistance guarantee in more severe environment such as guarantee in test (pressure cooker test; hereinafter abbreviated as PCT) under atmosphere of H or more and −2 atm, and PPB.
Defects on the order are being demanded.

In the conventional film capacitor shown in FIG. 8, 1 is a polyethylene naphthalate film having a thickness of 3.5 μm (hereinafter referred to as PEN film), and 2 is PEN.
Al vapor deposition films 4 formed on the film 1 are lead wires. As the thermal spray material, Zn metallikon 11 was used as the innermost layer, and then a Zn alloy containing 50 wt% Sn was sprayed to form the metallikon external electrode 12. The lead wire 4 and the metallikon external electrode 12 were welded by a method in which an electric current was passed through the Sn-plated lead wire 4 itself to cause self-heating and welding on the surface of the metallikon external electrode 12. FIG. 9 shows a film capacitor in which the case 22 is impregnated with resin 21 and is then packaged.

[0004]

With respect to the demand for improving the moisture resistance of the film capacitor, attention is paid to, for example, a metallized film capacitor, which is referred to as a vapor-deposited metal which is its counter electrode or a metallikon formed of a sprayed metal. The material of the external electrode is a major factor. This metallikon is
In order to prevent electrolytic corrosion due to local cell action, a metal having a low ionization potential and a small potential difference from the vapor-deposited metal is desired. However, the metallikon outer electrode 12 of the conventional film capacitor is usually Z
Since a thermal spray material containing n and Sn as the main components is used, it is difficult to escape from electrolytic corrosion due to local battery action. In addition, Zn,
When the lead wire 4 is welded to the metallikon external electrode 12 using a thermal spray material containing Sn as a main component, the metallikon external electrode 12 formed by thermal spray is subjected to considerable oxidation,
It is fragile and has a porous structure, and it is difficult to weld it to the lead wire 4, and its welding strength is weak. It is difficult to weld the highly reliable metallikon external electrode 12 and the lead wire 4 to each other.
It is difficult to meet the demand for defective rate on the PB order.

Therefore, in some cases, instead of the thermal spraying material containing Zn and Sn as the main components, a thermal spraying material containing Pb and Sn (solder material) as the main components is used to form the metallikon external electrode. In this case, the lead wire can be easily welded to the metallikon external electrode, and good moisture resistance can be obtained. However, when performing thermal spraying with Pb and Sn (solder material) as the main components, the safety and health of the thermal spraying operator himself due to the dust of Pb and environmental problems around the equipment become major problems. While more severe response to the recent environment is desired, enormous funds and equipment are required to completely solve the Pb dust problem.

Further, instead of the thermal spray material containing Zn and Sn as main components, a thermal spray material containing Cu and Zn as main components is formed as the first layer metallikon, and a lead wire is formed as the second layer metallikon. In some cases, a thermal spraying material containing Zn and Sn as main components is used for the welding. By forming the first layer metallikon by thermal spraying containing Cu and Zn as the main components, it is possible to slightly suppress electrolytic corrosion due to the local cell action, but as the second layer metallikon, Zn and Sn are formed. It is not a decisive solution because it is formed of thermal spray material as the main component. When the metallikon external electrode is formed only by the thermal spray material containing Cu and Zn as main components, the thermal spray material containing Cu and Zn as main components is Zn, Sn.
Because the melting point is higher than the thermal spray material containing
Welding with lead wires becomes very difficult. So Cu, Z
A metallikon external electrode is formed only with a thermal spray material containing n as a main component, and the metallikon external electrode and the lead wire are connected to Pb-S.
In some cases, a kind of brazing is performed via n (solder material) or Sn material. However, the metallikon external electrode formed by thermal spraying containing Cu and Zn as the main components is oxidized and has poor wettability with the brazing material Pb-Sn (solder material) or Sn material, and is brittle and porous. Due to the structure, it is difficult to weld with lead wires, the welding strength is weak and the reliability is low, and quite high temperature is required for welding. It is a disadvantage.

The present invention solves such a problem, and an object of the invention is to provide a film capacitor having a metallicon external electrode having a high mechanical strength and a highly reliable welding strength between the metallicon external electrode and a lead wire. And

[0008]

In order to achieve this object, the film capacitor of the present invention comprises an oxidation-inhibited Cu alloy layer sprayed with a Cu alloy containing 0.1 to 10% by weight of P as a spray material. It has a metallikon external electrode, and connects the metallikon external electrode and a lead wire through a brazing material of Sn-Pb alloy. Further, in order to further improve the characteristics of the film capacitor, the structure of the metallikon external electrode is multilayered. For example, the innermost layer of the metallikon external electrode is a metal having a small potential difference from the vapor-deposited metal of the metallized film constituting the film capacitor, such as Cu-Z.
An n alloy is used, and the next layer is a Cu alloy containing P. The metallikon external electrode and the lead wire are connected via a brazing material of Sn-Pb alloy.

[0009]

With this structure, in the film capacitor of the present invention, when the metallikon external electrode is formed by using the Cu alloy containing P as the sprayed metal, P reacts preferentially with O ₂ , so that the Cu of the sprayed metal is oxidized. Is suppressed or the oxide of Cu is reduced. That is, a reaction of 4P + Cu + 5O ₂ → 2P ₂ O ₅ + Cu 2P + 5CuO → P ₂ O ₅ + 5Cu occurs.

That is, C containing 0.1 to 10% by weight of P
The Cu alloy metallikon external electrode sprayed by using the u alloy as the spray material is hardly oxidized, and therefore this Cu alloy is
For example, a Pb-Sn alloy brazing material has good wettability, and since the bond strength between the spray particles is high, the mechanical strength of the metallikon external electrode itself is high,
The metallikon external electrode and the lead wire can be easily and firmly connected via the brazing material of the Sn-Pb alloy. Furthermore, it is possible to avoid electrolytic corrosion due to the action of the local battery, and it is possible to obtain good moisture resistance.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A film capacitor according to an embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) In FIG. 1, 1 is a thickness of 3.5.
μm polyethylene naphthalate (hereinafter referred to as PEN) film, 2 is A formed on PEN film 1
l evaporated film, 3 is a metallikon external electrode formed by thermal spraying, 4 is a lead wire, and 5 is a Pb-Sn alloy brazing material. The wire material of the alloy shown in Examples 1 and 2 of (Table 1) was used as the thermal spraying material, and the thermal spraying was performed from the direction of arrow 6 by arc spraying or plasma spraying.

[0013]

[Table 1]

The content of P in the Cu alloy depends on the Cu content during thermal spraying.
It should be an amount that minimizes the oxidation of the alloy. Therefore, the required amount of P varies depending on the atmosphere during thermal spraying. When performing thermal spraying with a non-oxidizing gas such as N ₂ , or when using a non-oxidizing gas in a vacuum vessel,
It is sufficient that the amount of P is 0.1 to 0.5% by weight. However, when performing in air like normal arc spraying,
It is necessary to increase the amount of P. However, if the amount of P exceeds 10% by weight, it becomes brittle as a P-Cu alloy, making it difficult to work as a wire material and impractical. Further, as the amount of P increases, the solidification shrinkage amount of the sprayed particles increases, and the residual correspondence and deformation of the sprayed layer increase, which is not practical. The practical range of P content in thermal spraying is 0.1% to 10% by weight.
Limited to

The residual stress of the P-Cu alloy and the amount of deformation at the time of thermal spraying differ depending on the amount of P contained in the P-Cu alloy before thermal spraying, but in order to suppress the residual stress and the amount of deformation at the time of thermal spraying to a practical level. , The thickness of 3a shown in FIG.
A range of 7 mm is effective.

As shown in Example 2 of (Table 1), A was added to P-Cu.
The reason for adding g is to lower the melting point and to reduce the oxidation of the sprayed metal particles. Especially 7P-20A
Since g-73Cu is a ternary eutectic and has a low melting point of 646 ° C., low temperature spraying is possible.

Then, the metallikon external electrode 3 and the lead wire 4 in which the oxidation due to the thermal spraying is suppressed as described above are Sn.
Through the Pb alloy brazing material 5, a heat source such as a soldering iron was contacted and connected. The temperature of the heat source is 250 ° C
For 2 seconds. This connection method may be any method as long as the brazing material 5 can be melted. It is also possible to melt the material and connect the lead wire 4.

When the lead wire 4 is welded via the Pb-Sn alloy brazing material 5, the welded portion of the surface of the metallikon external electrode 3 is polished or etched or the surface is treated with an organic acid or flux before welding. A reduction method is desirable. Further, the lead wire 4 is also Ni-on the lead wire 4 in order to improve the wettability with respect to the Pb-Sn alloy brazing material 5.
A method of forming a B coating or a Sn coating is desirable.

(Embodiment 2) In FIG. 2, 1 indicates a thickness of 3.5.
A PEN film 2 having a thickness of 2 μm is an Al vapor deposition film formed on the PEN film 1. This Al vapor-deposited film 2 and a sprayed metal having a small potential difference, for example, a Cu—Zn alloy metallikon 7 is used as the innermost layer, and then a P—Cu alloy is sprayed using the wire material of the alloy shown in Examples 1 and 2 of (Table 1). This was used as the metallikon external electrode 8. Reference numeral 4 is a lead wire, and 5 is a Pb-Sn alloy brazing material.

The reason why the sprayed metal in contact with the vapor-deposited metal is a metal having a small potential difference from the vapor-deposited metal is to prevent electrolytic corrosion due to local cell action.

Then, the metallikon external electrode 8 and the lead wire 4 in which the oxidation due to the thermal spraying is suppressed as described above are Sn.
The Pb alloy brazing material 5 was used for connection while being in contact with a heat source such as a soldering iron. The temperature of the heat source is 250 ° C
I was indirectly for 2 seconds.

When the lead wire 4 is welded through the Pb-Sn alloy brazing material 5, before welding, the welded portion of the surface of the metallikon external electrode 8 is polished or etched, or the surface is treated with an organic acid or flux. A reduction method is desirable. Further, the lead wire 4 is also Ni-on the lead wire 4 in order to improve the wettability with respect to the Pb-Sn alloy brazing material 5.
A method of forming a B coating or a Sn coating is desirable.

(Embodiment 3) Also in FIG. 3, similarly to Embodiments 1 and 2, an Al vapor deposition film 2 is formed on a PEN film 1 having a thickness of 3.5 μm, and a potential difference from the Al vapor deposition film 2 is small. Thermal spray metal, for example Cu-Zn alloy metallikon 7
As the innermost layer, and then using the wire materials of the alloys shown in Examples 3 and 4 of (Table 1), the Cu alloy metallikon 9 containing 20 wt% or more of Ag is sprayed, and further, (Table 1) Examples 1 and 4 2 P-
A Cu alloy was sprayed to obtain a metallikon external electrode 10. Reference numeral 4 is a lead wire, and 5 is a Pb-Sn alloy brazing material.

Since the Cu-Zn alloy metallikon 7 has a relatively large amount of oxidation, the bonding force between the Cu-Zn sprayed metal particles is weak. Therefore, when a thick P-Cu alloy is directly sprayed onto the Cu-Zn alloy metallikon 7, cracks are likely to occur inside the Cu-Zn sprayed metallikon 7 due to the solidification shrinkage force of the P-Cu alloy metallikon layer. In order to prevent cracks, forming an Ag-Cu alloy metallikon 9 with less oxidation as an intermediate layer as shown in FIG. 3 is an effective means.

Then, the metallikon external electrode 10 and the lead wire 4 which are suppressed from being oxidized by the thermal spraying in this manner are separated from each other by S.
The n-Pb alloy brazing material 5 was used for connection while being in contact with a heat source such as a soldering iron. The temperature of the heat source is 250
Indirect for 2 seconds at ° C.

When the lead wire 4 is welded through the Pb-Sn alloy brazing material 5, before welding, the welded portion of the surface of the metallikon external electrode 10 is polished or etched, or the surface is treated with an organic acid or flux. A reduction method is desirable. Further, the lead wire 4 is also Ni-on the lead wire 4 in order to improve the wettability with respect to the Pb-Sn alloy brazing material 5.
A method of forming a B coating or a Sn coating is desirable.

Comparative Example As a comparative example, a conventional film capacitor shown in FIG. 8 was used. In each of the examples and the comparative examples, the lead wire and the metallikon external electrode were welded by applying a current to the Sn-plated lead wire itself to cause self-heating and welding on the surface of the metallikon external electrode.

The film capacitors of Example 1, Example 2, Example 3 and Comparative Example were subjected to D in an atmosphere of 60 ° C. and 95% RH.
The results of the moisture resistance load test when C250V is applied are shown in FIG.

FIG. 5 shows the lead wire terminal strength of the film capacitors of Example 1, Example 2, Example 3, and Comparative Example. The method of measuring the lead wire terminal strength was the method shown in FIG. 6, and the strength when the lead wire 4 was detached from the metallikon external electrode 20 was measured.

As shown in FIG. 4, the moisture resistance characteristics of the film capacitors of Examples 1, 2 and 3 of the present invention are as follows.
Good results were obtained in comparison with the moisture resistance characteristics of the comparative example.

Then, as shown in FIG. 5, the lead wire terminal strengths of the film capacitors of Examples 1, 2 and 3 are significantly higher than those of the film capacitors of Comparative Examples. It was

(Example 4) The film capacitors formed in Example 1, Example 2, Example 3, and Comparative Example were formed into a hollow case structure as shown in FIG. The case type film capacitor of Example 3 obtained sufficient lead wire terminal strength and electric characteristics. However, in the case type film capacitor of the comparative example, since the lead wire terminal strength of the comparative example itself was weak, the lead wire 4 and the metallikon external electrode 12 were detached when the case was attached, and the capacitor electric characteristics could not be obtained.

That is, as in the case of the conventional film capacitor, the case 22 having the structure shown in FIG. 9 is resin-impregnated 21 and is then packaged, as shown in FIG. Resin impregnation 21 is no longer necessary,
It is possible to greatly omit the exterior process.

In the embodiment of the present invention, a laminated film capacitor using a PEN film is used, but a film capacitor having a wound structure is also used in place of the PEN film. Similar effects can be obtained by using polyethylene terephthalate, pyripropylene, pyriphenylene sulfide, etc.

[0035]

As is apparent from the above description of the embodiments, according to the film capacitor of the present invention, 0.1 to 1 is used.
A Cu alloy containing 0% by weight of P was sprayed as a spray material,
A metallikon external electrode including a Cu alloy layer in which oxidation is suppressed is provided, and the metallikon external electrode and the lead wire are made of Sn-Pb.
Since the structure is connected through the brazing material of the alloy, the metallicon external electrode and the lead wire are coupled with the brazing material of the Sn-Pb alloy together with the mechanical strength of the metallicon external electrode itself. It can be easily and firmly connected, and resin impregnation and outer packaging for improving the lead wire terminal strength, which is used in film capacitors that use metallikon external electrodes, are not required and the outer packaging process can be greatly omitted. is there.

Further, with this structure, it is possible to avoid electrolytic corrosion due to the action of the local battery, and it is possible to obtain good moisture resistance.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing the structure of a film capacitor according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional view showing the structure of a film capacitor according to a second embodiment of the present invention.

FIG. 3 is a vertical sectional view showing the structure of a film capacitor according to a third embodiment of the present invention.

FIG. 4 is a graph showing the results of a moisture resistance load test when DC250V is applied to the film capacitors of Examples 1, 2 and 3 of the present invention and a comparative example in a 60 ° C.-95% RH atmosphere.

FIG. 5 is a graph showing the lead wire terminal strength.

FIG. 6 is a schematic diagram showing a method of measuring lead wire terminal strength.

FIG. 7 is a vertical cross-sectional view showing the structure of a film capacitor provided with a hollow casing according to a fourth embodiment of the present invention.

FIG. 8 is a vertical sectional view showing the structure of a conventional film capacitor.

FIG. 9 is a vertical cross-sectional view showing the structure of a conventional film capacitor having a resin-impregnated case exterior.

[Explanation of symbols]

 1 Dielectric Film 2 A1 Evaporated Film (Electrode) 3 Metallicon External Electrode 4 Lead Wire 5 Brazing Material

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Minoru Kikuchi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Kenji Kuwata, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. A laminated body or a wound body of a plurality of electrodes and a dielectric film made of one or more layers of organic material, which is arranged between the electrodes, and the electrode lead-out end face, each of which is provided with the electrode. And a metallikon external electrode including an oxidation-inhibited Cu alloy layer sprayed with a Cu alloy containing 0.1 to 10% by weight of P as a spraying material, which is electrically connected alternately with A film capacitor equipped with lead wires connected through attachment materials. 2. The film capacitor according to claim 1, wherein the metallikon external electrode is composed of a plurality of metal layers. 3. Among the plurality of layers of the metallikon external electrode,
The film capacitor according to claim 2, wherein the innermost layer is a Cu-Zn alloy. 4. The film capacitor according to claim 2, wherein the layer formed by thermal spraying on the inner side of the Cu alloy layer containing P is a Cu alloy containing 20% by weight or more of Ag. 5. A laminated body or a wound body of a plurality of electrodes and a dielectric film made of one or more layers of organic material, which is arranged between the electrodes, and an electrode lead-out end face of the laminated body or the wound body. And a metallikon external electrode including an oxidation-inhibited Cu alloy layer sprayed with a Cu alloy containing 0.1 to 10% by weight of P as a spraying material, which is electrically connected alternately with A film capacitor comprising a lead case connected through a mounting material, and a hollow case outer casing not having an outer casing impregnated with a resin for holding the lead wire.