JPH0296319A - Manufacture of metallized film capacitor - Google Patents

Abstract

PURPOSE:To stabilize initial characteristics and secure a long-term reliability by forming a capacitor element with a specific polyphenylenesulfide film as a dielectric and an aluminum deposited film as an electrode and by performing heat treating. CONSTITUTION:After forming a capacitor element with a polyphenylenesulfide film having an xylene extractability of 0.4 to 1.5% as one part and an aluminum deposited film as an electrode, it is subjected to heat treating at a temperature ranging from 110 deg.C to 270 deg.C. The polyphenylenesulfide film is a biaxial orientation film of resin composition which mainly consists of poly-p-phenylenesulfide. It stabilizes initial characteristics and achieves a capacitor which is superb in moisture resistance and long-term reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to six methods for manufacturing metallized film capacitors.

[Conventional technology] Capacitors with aluminum vapor deposited films as electrodes and plastic films as dielectrics have higher precision in terms of temperature and frequency stability, are smaller than capacitors with aluminum foil electrodes, and have better self-healing properties. It is already widely used for several reasons. Furthermore, it has recently been known from Japanese Patent Laid-Open No. 187327/1983 that a polyphenylene sulfide film can be used as a dielectric to obtain a capacitor with excellent heat resistance and extremely high precision.

On the other hand, a technique is known in which a wound body or a laminate containing a film capacitor element is pressurized under heat to form the element and stabilize capacitor characteristics such as initial capacitance.

[Problems to be Solved by the Invention] However, conventional metallized polyphenylene sulfide film capacitors using aluminum vapor-deposited films as electrodes often have the drawback that they cannot stabilize initial characteristics and ensure long-term reliability. Specifically, capacitors that have been heat-treated at high temperatures to stabilize their initial characteristics have a poor moisture-resistant life. There was a drawback that the vapor-deposited aluminum film disappeared and the capacity quickly decreased. -For in-shell film capacitors,
Although the higher the heat treatment is performed at a higher temperature, the more effective it is to stabilize the initial characteristics and the longer the moisture resistance life is, in the case of aluminum metallized polyphenylene sulfide film capacitors, the higher the heat treatment is performed, the longer the moisture resistance life is. This has made it extremely difficult to stabilize initial characteristics and ensure long-term reliability.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of conventional aluminum metalized polyphenylene sulfide film capacitors, and to create a metalized polyphenylene sulfide film capacitor that has stable initial characteristics, excellent moisture resistance life, and sufficiently ensures long-term reliability. The purpose is to provide a manufacturing method.

[Means for Solving the Problems] The present invention uses a polyphenylene sulfide film with a xylene extraction amount of 0.4% or more and 1.5% or less as at least a part of the dielectric, and an aluminum vapor-deposited film as at least a part of the electrode. After forming the capacitor element, the temperature is 110°C.
The present invention relates to a method for manufacturing a metallized film capacitor, which is characterized by heat treatment at a temperature of 270° C. or lower.

The present invention requires the use of polyphenylene sulfide film as the dielectric. However, not all dielectrics need to be polyphenylene sulfide films, and other dielectrics may be used as long as they do not impede the heat resistance, temperature characteristics, etc. that are the features of polyphenylene sulfide films.
For example, resin compositions such as polyethylene terephthalate, polyethylene naphthalate, polyolefin, polycarbonate, polyphenylene oxide, polyetheretherketone, polyetherimide, etc. may also be used as the dielectric material.

In the present invention, polyphenylene sulfide film (
(hereinafter sometimes abbreviated as PPS film) is a biaxially oriented film of a resin composition containing poly-p-phenylene sulfide as a main component.

The thickness of the film is preferably in the range of 0.2 μm to 25 μm. The average surface roughness Ra of the film is 0.01 μm-0.15 from the viewpoint of handling workability of the film, formability of capacitor elements, and adhesion with aluminum thin film.
Preferably it is μm. In addition, 230% of the film
The heat shrinkage rate at ℃ for 10 minutes is 0% to +12% in the longitudinal direction of the film due to the characteristic stability of the resulting capacitor.
, preferably -5% to +5% in the direction perpendicular to the longitudinal direction.

Here, the resin composition containing poly-p-phenylene sulfide as a main component (hereinafter sometimes abbreviated as PPS resin composition) refers to a composition containing 70% by weight or more of poly-p-phenylene sulfide.

Content of poly-p-phenylene sulfide is 70% by weight
If it is less than that, the characteristics of the film made of the composition such as heat resistance, frequency characteristics, temperature characteristics, etc. will be impaired. The metal component contained in the PPS resin composition has a weight average standard electrode potential Eo of the metal of -1.5 V or less, and the total content of the metal MY (unit: ppm> is 80≦ Y≦7
00, and the weight of the metal that can be extracted with chloroform × (unit: DDm) satisfies the following formula (1) with respect to the weight of the resin composition containing the poly-p-phenylene sulfide as a main component. preferable.

O≦X≦(0,5Y-40>
It is sometimes abbreviated as PS. ) means the repeating unit 7
0 mol% or more (preferably refers to a polymer consisting of 85 component units. If this component is less than 70 mol%, the crystallinity of the polymer
Heat resistance, dimensional stability, which is a feature of a film made of a resin composition mainly composed of PPS, which has a low heat transition temperature, etc.
Damages mechanical properties, etc. The melt viscosity of PPS is 300℃
, 500 ~ under shear rate 200 s e C-1
A range of 15,000 poise is preferred. This value does not change even after it is made into a film or vapor-deposited film.

The polyphenylene sulfide film used in the present invention needs to have a xylene extraction amount of 0.4% to 1.5%, preferably 0.4% to 1.2%.

If the xylene extraction amount exceeds 1.5%, a sufficient moisture-resistant life cannot be guaranteed, and if the extraction amount is less than 0.4%, the adhesion to the vapor-deposited aluminum film or film will not be sufficient.

A method for obtaining a polyphenylene sulfide film with a xylene extraction amount of 0.4% or more and 1.5% or less is to wash poly-p-phenylene sulfide in powder form in advance with a solvent such as diphenyl ether under appropriate conditions. A method of obtaining polyphenylene sulfide by removing most of the low molecular weight components contained in poly-p-phenylene sulfide and then forming it into a film, a method of obtaining it by extracting a polyphenylene sulfide film with an organic solvent such as xylene, etc. These examples include, but are not limited to. In general, it is preferable that the difference obtained by subtracting the amount of acetone extracted from the amount of xylene extracted is 0.1% or more and 1.4% or less (preferably 1.2% or less).

The extraction amount remains unchanged even after aluminum deposition. Further, it is preferable that the weight of the hot water extractable metal is 50 D 0m or less.

Next, when an electrode is provided on the polyphenylene sulfide film or other resin film, aluminum is vacuum-deposited on the resin film. At this time, the surface resistance of the deposited film is 0.5 from the viewpoint of the balance between moisture resistance life and self-healing property.
It is preferable to set it in the range of ~10Ω. Furthermore, it is also preferable to subject the surface of the film to be vapor-deposited to corona treatment, plasma treatment, etc. before vacuum-depositing aluminum, from the viewpoint of improving the adhesion between the aluminum-deposited film and the film.

Vacuum deposition can be carried out by a conventional method using a continuous winding type deposition machine or the like. The deposition surface may be either single-sided or double-sided depending on the type of capacitor to be obtained.

It is a common practice to provide a non-vaporized portion (so-called margin) using a tape mask, oil mask, laser beam, etc. to prevent short-circuiting of opposing electrodes during or after vapor deposition.

The type of capacitor desired may be any of the known metallized film capacitors. That is, the capacitor element may be formed by any known method such as winding or lamination, or by a new method. For example, in the case of a single-sided vapor deposited film, two layers are stacked, in the case of a double-sided vapor deposited film, a non-deposited film is used, and if a dielectric layer is provided on the film by double-sided vapor deposition, etc., a single film is wound. Alternatively, there is a method of laminating layers to obtain a capacitor element, but the non-deposited surface of the polyphenylene sulfide film is overlapped with the surface of the aluminum deposited film that will become the electrode formed on the polyphenylene sulfide film or other film, sheet, etc. The present invention is most effective when the type of capacitor is used.

The obtained capacitor element usually goes through a pressing process, an external electrode attachment process (using metal spraying, conductive resin, etc.), a lead-type capacitor, a lead wire attachment process, and an exterior packaging process. However, in the present invention, it is necessary to heat-treat the capacitor element at a temperature of 110'C to 270'C at some stage before it becomes a capacitor.

By performing this heat treatment, properties such as initial capacity stability, long-term load resistance, and moisture resistance life are dramatically improved.

Here, the term "capacitor element" refers to a state in which vapor-deposited film electrodes and films are alternately stacked, and includes, for example, an intermediate in the middle of winding.

The specific steps and methods of the heat treatment are not particularly limited, but either a method of heating at the same time as pressure is applied during pressing, or a method of aging in a heating oven after removing the external electrode or lead wire. is preferable because the process is simple. In particular, a method of applying pressure and heating at the time of pressing is preferable since it is easy to impart mechanical strength to the element. If the temperature of the heat treatment is 110° C. or lower, heat resistance, capacity stability, etc. are insufficient, and if the temperature of the heat treatment is 270° C. or higher, the withstand voltage failure rate increases.

A more preferable range of the heat treatment temperature is 150'C to 25'C.
It is 0°C. In addition, the time for performing the heat treatment depends on the temperature,
Although it cannot be stated unconditionally because it is correlated with the desired characteristics of the capacitor, etc., it is generally in the range of 1 minute to 10 hours.

The form of the capacitor obtained by the present invention is not particularly limited. That is, as mentioned above, it may be of any known type, such as a wound type, a laminated type, a leaded type, a so-called chip capacitor without a lead, etc., and is not limited to these types. In addition, the exterior packaging methods include resin mold, resin dip,
It may be a case, a resin film, or a material with substantially no exterior, such as a surface coated with a thin resin, and is not limited to these, but the effects of the present invention are best exhibited. is a chip capacitor that has the strongest demand for miniaturization, and has a substantially unpackaged or extremely simple package that requires high heat resistance.

[Method for evaluating properties] (1) A film with a xylene extraction amount of about 50 is cut into strips of about 2 cm 2 and extracted with xylene using a Soxhlet extractor. Pour xylene into the flask at the bottom of the Soxhlet extractor, immerse it in an oil bath heated to 200°C, and extract for 36 hours. After the extraction is complete,
The extract is evaporated to dryness at 160°C and the extract is weighed. The extract weight is divided by the film weight before extraction to obtain the extraction amount, and the percentage is
Display in .

In the case of a vapor-deposited film, aluminum is dissolved in a 5% NaOH aqueous solution and dried, and then measured using the method described above.

(2) Acetone Extraction Amount: Cut a film containing about 5 g into strips of about 2 cm 2 and extract with acetone using a Soxhlet extractor. Pour xylene into the flask at the bottom of the Soxhlet extractor, immerse it in an oil bath heated to 80°C, and extract for 24 hours. After the extraction is completed, the extract is evaporated to dryness at 80°C and the extract is weighed. The weight of the extract is divided by the weight of the film before extraction to determine the amount of extract, and is expressed in %.

In the case of a vapor-deposited film, aluminum is dissolved in an 85% Na0 aqueous solution, dried, and then measured using the method described above.

(3) Evaluation of reliability (humidity life) of capacitors under high temperature and high humidity environments.
The capacitance change rate is measured by time aging. This was expressed as ΔC/C and was taken as the moisture resistance life test result. here,
C is the capacitance before aging, and ΔC is the amount of change in capacitance before and after aging. The larger the absolute value of this value, the shorter the moisture resistance life, that is, the greater the capacity drop in high temperature and high humidity environments, and the lower the reliability. Note that the capacitance of the capacitor is measured using an automatic capacitance bridge.

(4) Evaluation of capacitor initial capacitance stability 1000 capacitors were manufactured under the same conditions, the capacitance of each capacitor was measured using an automatic capacitance bridge, and the variation (standard deviation) was expressed in % and the initial capacitance was stabilized. It was made into a sex. The smaller this value is, the higher the stability is.

(5) Evaluation of capacitor withstand voltage failure rate 1000 capacitors were manufactured under the same conditions, the withstand voltage of each capacitor was measured, and the percentage of capacitors that did not reach the specified voltage was calculated and expressed as a percentage, which is the withstand voltage failure rate. do. In addition, the voltage was applied while increasing at a rate of 100 V/sec,
The voltage at which the capacitor was destroyed and a current of 10 mA or more flowed was defined as the withstand voltage.

Further, the specified voltage was 50 μm per 1 μm of film thickness.

(6) Metal content in polyphenylene sulfide film Polyphenylene sulfide film is
After dissolving in chloronaphthalene, it is filtered through a 0.1 μφ cut filter to remove solids such as inert particles. Next, α-chloronaphthalene is distilled off from this filtrate to obtain polyphenylene sulfide powder. Next, the polyphenylene sulfide powder (approximately 100Q>) was placed in a platinum crucible and incinerated in an electric furnace.
It was filtered into dilute nitric acid. Further, the residue was incinerated together with the filter paper, and dissolved in 0.50% potassium hydrogen sulfate to form a dilute nitric acid solution.

Each solution was quantitatively determined by plasma emission spectrometry (ICP analysis), and the contents of each solution were added together to determine the metal content in the polyphenylene sulfide film.

(7) Chloroform-extractable metal-containing skewer 200-2
Polyphenylene sulfide film 10C1 ground into 50 meshes is extracted with 100 g of chloroform by refluxing it in a Soxhlet extractor at an oil bath temperature of 120° C. for 120 hours.

Next, chloroform is distilled off from this extract, and the resulting solid content and/or liquid is used to determine the content of various metals in the same manner as in the measurement in (1) above.

(8) Content of hot water extractable metals 10Q polyphenylene sulfide film pulverized to 200 to 250 meshes and 300q of ion-exchanged water were placed in a 1L titanium autoclave and replaced with nitrogen at 100°C, then the autoclave was sealed. Extraction was carried out at 180'C for 30 hours with stirring, followed by filtration with a 0.5μ filter. After appropriately concentrating the filtrate, the amount of metal is determined by plasma emission spectrometry (ICP analysis).

[Effects of the Invention] The capacitor manufactured by the method of the present invention has stable initial characteristics, excellent moisture resistance life, and sufficiently ensures long-term reliability.

[Example] Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 (1) Preparation of PPS film 32.6k (1(2)
50 mol, containing 4 Qwt% of crystal water), 100 g of sodium hydroxide, 36°1 kg of sodium benzoate (250
mole), and N-methyl-2-pyrrolidone (hereinafter referred to as NMP
(sometimes abbreviated as )79°2k (prepare l and
After dehydration at °C, 1,4 dichlorobenzene (p-D
(abbreviated as CB) 37°5 kg (255 mol), and N
MP20.0kCI was added and reacted at 265°C for 4 hours. The reaction product was washed with water and dried to obtain 21.1 kg (78% yield) of poly-p-phenylene sulfide containing 100 mol % of p-phenylene sulfide and having a melt viscosity of 3100 voids.

The obtained polymer was washed and extracted with diphenyl ether at 100'C to remove low molecular weight components and impurity components.

In this composition, fine silica powder Q with an average particle size of 0.7 μm is added.
, '1wt%, calcium stearate 0゜05wt%
310 with a 4Qmm diameter extruder.
95% cut hole diameter 10 using metal fiber melted with 'C
After filtering with a μm filter, the length is 400 mm, and the gap is 1.
．． Extruded from a T-die with a 5 mm linear lip,
It was cast on a metal drum whose surface was kept at 25°C and solidified by cooling to obtain an unstretched film with a thickness of about 20 μm.

This film is stretched by a longitudinal stretching device consisting of a group of rolls.
3 at a film temperature of 100°C and a stretching speed of 30,000%/min.
．． Stretched 6 times, then using a tenter at a temperature of 100°C.
Stretching speed 1. It was stretched 3.5 times in OO037 minutes, and then heat treated under tension at 270° C. for 10 seconds in a subsequent heat treatment chamber in the same tenter to obtain a PPS film with a thickness of 2 μm. The amount of xylene extracted from this film was 0.60%.

(2) Metallization The surface of the above film to be subjected to aluminum vapor deposition was subjected to corona treatment, and aluminum was vacuum vapor-deposited so that the surface resistance value was 20. At that time, the vapor deposition was performed in a stripe shape having a margin section running in the longitudinal direction (the width of the vapor deposition section was 9.9 mm).
Qmm, width of margin part 1. (repetition of Qmm).

(3) Manufacture of rolled body A blade was inserted into the center of each vapor deposited part and the center of each margin part to make a slit, and the tape was wound into a tape having a total width of 4.5 mm with a margin of Q on the left or right and a margin of 5 mm. .

1q of tapes are wrapped one on top of the other on the left margin and one on the right margin, and the capacitance is 0.1μ.
A wound body of F was obtained. At that time, the two films were wound with an offset so that the vapor-deposited part protruded from the margin part by Q, 5 mm in the width direction.

(4) Manufacture of capacitors Handle the core material from this wound body and heat it to 180°C11 as it is.
0kc+/cm2 (7) Temperature, pressure T” 5 molecules l
jl 7 responded. Metallicon was thermally sprayed on both end faces of this to form external electrodes, and lead wires were welded to the metallicon to obtain a capacitor. This is called capacitor 1. Table 1 shows the capacitor initial capacity stability, withstand voltage failure rate, and moisture resistance life evaluation results for Capacitor 1.

Example 2 A capacitor was obtained in exactly the same manner as in Example 1, except that the temperature at which the wound body was pressed was 240°C. This is called capacitor 2. Table 1 shows the capacitor initial capacitance stability, withstand voltage failure rate, and moisture resistance life evaluation results for Capacitor 2.

Example 3 A wound body obtained in the same manner as in Example 1 was heated at 100°C and 30k.
It was pressed for 5 minutes at a temperature and pressure of q/cm2. This was thermally sprayed with metallicon on both end faces to form external electrodes, and after welding one underline to the metallicon, it was aged in an oven at 220° C. for 1 hour to obtain a capacitor. This is called capacitor 3. Initial capacitance stability of capacitor 3,
Table 1 shows the withstand voltage failure rate and moisture resistance life evaluation results.

Example 4 A capacitor was obtained in exactly the same manner as in Example 1, except that the temperature at which the wound body was pressed was 120°C. This will be referred to as capacitor 4. Table 1 shows the capacitor initial capacitance stability, withstand voltage failure rate, and moisture resistance life evaluation results for Capacitor 4.

Example 5 A capacitor was obtained in exactly the same manner as in Example 1, except that the temperature at which the wound body was pressed was 260°C. This will be referred to as capacitor 5. Table 1 shows the capacitor initial capacitance stability, withstand voltage failure rate, and moisture resistance life evaluation results of Capacitor 5.

Example 6 A capacitor No. 14 was prepared in the same manner as in Example 3 except that the aging temperature was 260°C.

This will be referred to as capacitor 6. Table 1 shows the capacitor initial capacitance stability, withstand voltage failure rate, and moisture resistance life evaluation results of Capacitor 6.

Example 7 PP was prepared in the same manner as in Example 1, except that the temperature when washing and extracting the polymer with diphenyl ether was 90°C.
An S film was obtained. Xylene extraction of this film is 1
．． It was 15%. A capacitor was obtained using this film in the same manner as in Example 2. This will be referred to as capacitor 7. Table 1 shows the capacitor initial capacitance stability, withstand voltage failure rate, and moisture resistance life evaluation results of Capacitor 7.

Example 8 Polymer was washed with diphenyl ether and P was prepared in the same manner as in Example 1 except that the temperature during extraction was 75°C.
1q of PS film. The amount of xylene extracted from this film was 1.42%. Example 1 using this film
Condensate was obtained in the same manner. This capacitor 8
shall be. Table 1 shows the capacitor initial capacitance stability, withstand voltage failure rate, and moisture resistance life evaluation results of Capacitor 8.

Example 9 A capacitor was obtained in exactly the same manner as in Example 8, except that the temperature at which the wound body was pressed was 240°C. This will be referred to as capacitor 9. Table 1 shows the capacitor initial capacitance stability, withstand voltage failure rate, and moisture resistance life evaluation results of Capacitor 9.

Comparative Example 1 A PPS film was obtained in the same manner as in Example 1 except that the polymer was not washed with diphenyl ether or extracted. The amount of xylene extracted from this film was 2.12%. A capacitor was produced from this film in the same manner as in Example 1. This will be referred to as a capacitor 10. Capacitor initial capacitance stability of capacitor 10, withstand voltage failure rate,
The moisture resistance life evaluation results are shown in Table-1.

Comparative Example 2 The PPS film produced in Comparative Example 1 was washed with chloroform at 70° C. for 24 hours. The amount of xylene extracted from this film was 0.31%. A capacitor was obtained using this film in the same manner as in Example 2. This will be referred to as capacitor 11. Table 1 shows the capacitor initial capacitance stability, withstand voltage failure rate, and moisture resistance life evaluation results of capacitor 11.

Comparative Example 3 A capacitor 10 identical to the capacitor 10 produced in Comparative Example 1 was prepared, and the exterior was applied by dipping it in molten epoxy resin and curing it by heating. The average thickness of the exterior was approximately 2 mm. This will be referred to as capacitor 12. Table 1 shows the initial capacitor capacity stability, withstand voltage failure rate, and moisture resistance life evaluation results of capacitor 12.

Comparative Example 4 The same PPS film as the comparative example was prepared,
A capacitor was produced from this film in the same manner as in Example 3. This will be referred to as capacitor 13. capacitor 1
Table 1 shows the initial capacitance stability, withstand voltage failure rate, and moisture resistance life evaluation results of No. 3 capacitor.

Comparative Example 5 A capacitor was obtained in exactly the same manner as in Example 1, except that the temperature at which the wound body was pressed was 100°C. This will be referred to as a capacitor 14. Table 1 shows the initial capacitor capacity stability, withstand voltage failure rate, and moisture resistance life evaluation results of capacitor 14.

Comparative Example 6 A capacitor was obtained in exactly the same manner as in Example 1, except that the temperature when pressing the wound body was 275°C. This will be referred to as capacitor 15. Table 1 shows the capacitor initial capacitance stability, withstand voltage failure rate, and moisture resistance life evaluation results of capacitor 15.

As described above, capacitors manufactured using conventional manufacturing methods are unable to both stabilize initial characteristics and ensure a long moisture-resistant life, whereas capacitors manufactured using the present invention have stable initial characteristics and are sufficient even without packaging. It can be seen that a long moisture-resistant life is ensured.

Claims (1)

[Claims] After forming a capacitor element in which a polyphenylene sulfide film with a xylene extraction amount of 0.4% or more and 1.5% or less is used as at least a part of the dielectric material and an aluminum vapor-deposited film is used as at least a part of the electrode, the temperature is set at 110°C or more and 27°C.
A method for producing a metallized film capacitor, characterized by heat treatment at a temperature of 0°C or lower.