JPS61273877A - Capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field The present invention relates to a capacitor.

[Prior art]

Conventionally, biaxially oriented polyphenylene sulfide films have been used as dielectric materials for capacitors to improve frequency characteristics, temperature characteristics,
To obtain a capacitor with excellent solder resistance
7-187327 etc.

Furthermore, capacitors using heat-resistant films such as polyimide films and aromatic polyamide films as dielectrics are also known.

[Problems to be solved by the present invention]

So-called film capacitors, which use plastic film as a dielectric, have excellent electrical properties and are often used in circuits that require precision, such as time constant circuits.
In order to miniaturize circuits and improve mounting efficiency, there is a demand for film capacitors to be made into chips.

However, since chip capacitors (hereinafter referred to as chip capacitors) are directly attached to circuit boards by dipping them into a solder bath during mounting, the entire capacitor is exposed to extremely high temperatures, and polyester ．． Polypropylene, polycarbonate. Typical capacitors whose dielectric material is polystyrene, etc., lack heat resistance even if they have a thick outer case, resulting in significant changes in capacitance, decrease in insulation resistance, and poor connections during mounting. Because of this, it was not possible to convert it into chips.

□ , On the other hand, if polyimide film, aromatic polyamide film, etc. are used as a dielectric material, it is possible to make chips from the viewpoint of solder heat resistance. Capacitors have poor electrical characteristics and
The features of the ilm capacitor have been lost.

Therefore, I
Therefore, it was proposed to use biaxially oriented polyphenylene sulfide film as a dielectric material.
However, with such a capacitor, N
(However, unless the outer periphery of the element is covered with a thick outer casing, satisfactory solder resistance cannot be obtained, which increases the external dimensions and does not meet the purpose of miniaturizing the circuit by making it into a chip.)

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks of conventional capacitors, and improves electrical characteristics and solder resistance.
The purpose of the present invention is to provide a capacitor that is small and has high mounting efficiency while also achieving both performance and performance.

[Structure of the invention]

In order to achieve the above object, the present invention has a main dielectric consisting of a biaxially oriented film of a resin composition containing poly-p-phenylene sulfide as a main component, and electrodes are deposited on the surface of the dielectric film. In a capacitor made of a metal thin film, the heat shrinkage rate of the deposited film at 250°C for 10 minutes is 0 to 6% in the longitudinal direction of the film and 12 to 2% in the width direction.
%, and an electrode lead-out member that does not melt at 260° C. is provided at both ends of the capacitor element, and the member covers all of both end surfaces and a part of the lower surface of the capacitor, and the capacitor is substantially free. This capacitor is characterized by its exterior packaging.

In the present invention, poly-roof unison sulfide means:
It refers to a polymer in which 70 mol% or more (preferably 85 mol% or more) of repeating units consists of constitutional units represented by the general formula +o-5. If the content of such components is less than 70 mol%, the crystallinity, thermal transition, temperature, etc. of the polymer will decrease, and the heat resistance, dimensional stability, Damages mechanical properties, etc.

Less than 30 mol% of repeating units, preferably 15 mol%
If the amount is less than that, it is acceptable even if a unit containing a copolymerizable sulfide bond is included.

In this Q, a resin composition containing poly-p-phenylene sulfide as a main component (hereinafter sometimes abbreviated as PPS) refers to a composition containing 90% by weight or more of the above-mentioned poly-p-phenylene sulfide.

Content of poly-p-phenylene sulfide is 901% by weight
The crystallinity of the composition, the thermal transition temperature,
etc., and the film made of the composition and...
The features of the laminate are heat resistance, dimensional stability,
Damages mechanical properties, etc.

The remaining less than 10% by weight of the composition can consist of polymers other than poly-roof unitine sulfide, inorganic or organic photoadditives, and the like. In addition, additives such as inorganic or organic lubricants, colorants, and ultraviolet absorbers may also be included.

The melt viscosity of the resin composition is preferably in the range of 500 to 12,000 voids (more preferably 700 to 7,000 voids) at a temperature of 300° C. and a shear rate of 200 1/See in terms of film formability.

In the present invention, biaxially oriented polyphenylene sulfide film (hereinafter sometimes abbreviated as PP5-BO film) is formed by melt-molding the above PPS and forming it into a sheet shape.
This film is made by biaxial centrifugation and heat treatment.

The degree of orientation of the film was determined to be 2θ-20 to 2 by wide-angle X-ray diffraction.
The degree of orientation (OF) determined for one crystal peak is En
0.1 to 0.6 in d direction and Edge direction, Thro
It is preferably in the range of 0.6 to 1.0 in the ugh direction.

Moreover, the thickness of the film is preferably in the range of 0.3 to 5 microns.

The average surface roughness Ra of the film measured by the method specified in JIS R-0601
is preferably in the range of 0.03 to 0.20 microns. The coarse protrusion density Ld (protrusion height') of the film:
(referring to the linear density of protrusions of 0.2 microns or more) is 5 (more preferably 3) protrusions/
- It is preferable that it is below. In addition, the film has a fine protrusion density Sd (meaning the linear density of protrusions with a protrusion height of 0.02 < micron or more) of 20 to 300 (more preferably 3
It is preferably in the range of 0 to 200) pieces/am.

Here, the protrusion height is measured by a stylus-type surface roughness needle (cutoff value 0.08 mm, stylus radius 2 microns), measured over the length of the film [■ The level of the top of the first peak on the chart of the roughness curve is Mi, and the level of the bottom of the valley to the left of the first peak is vl, then Pi = (Mi-Vi)/N of the first protrusion. Defined as protrusion height.

The electrode of the capacitor of the present invention is a metal thin film deposited on the surface of PP5-BO as a support, and its thickness is preferably 0.01 to 0.5 μm.

The materials of these metal thin films are not particularly limited, but include aluminum, zinc, tin, nickel, and chromium.

Iron, copper, titanium, or an alloy thereof is preferable, and nickel and chromium have moisture resistance.

More preferred are titanium, zinc, or alloys thereof.

The membrane resistance value of the electrode is preferably in the range of 0.5Ω to 50Ω.

In the present invention, the metallized film is pps-BO on which a metal thin film as described above is formed on the surface, and its heat shrinkage rate at 250 degrees for 10 minutes is 0 to +6% (preferably) in the longitudinal direction of the film. is in the range of +1 to +4%) and -2 to +2% (preferably -1 to +1%) in the width direction of the film.

If the thermal shrinkage rate is outside this range, defects such as capacitance change, insulation resistance drop, and poor connection will occur when soldering the capacitor.

The capacitor of the present invention uses the above-mentioned PP5-BO as its main dielectric, and the capacitor of the present invention has temperature characteristics and frequency characteristics.

As long as solder resistance etc. are not impaired, there is no problem in that an insulating layer other than PP5-BO is present between the electrodes together with PP5-BO. Examples of such insulating layers include polysulfone, polyphenylene oxide, polycarbonate,
Examples include, but are not limited to, polyether sulfone, polyetherimide, and fluororesin.

The capacitor of the present invention has electrode extension members that do not melt at 260° C. on both end faces of the capacitor element as electrode extension parts for connecting the aforementioned electrodes to an external circuit. Examples of the structure of the electrode lead-out member include high melting point metallicon with a melting point exceeding 260°C, thermosetting conductive paste, and usually sprayed metallicon, which is covered with a metal camp mechanically fixed to the element body. can do 0
In the present invention, the electrode extension member covers all of both end surfaces and a portion of the lower surface of the capacitor. By adopting such a structure, when soldering a chip capacitor to a circuit board, the electrical connection between the circuit board and the capacitor becomes more secure, which reduces the time required for soldering and prevents capacitance changes and insulation during soldering. It is possible to prevent a decrease in resistance, a decrease in withstand voltage, etc.

The capacitor of the present invention is substantially without armor.

No-exterior means that the outer periphery of the capacitor element has a thickness of 0.0 mm and has the ability to protect the capacitor element from heat and mechanical external forces.
It is used as an electric circuit component without providing an outer covering layer of approximately 2-II or more (hereinafter simply referred to as an outer layer).

Therefore, the core and outer periphery (for multilayer capacitors, the core and outer periphery during simultaneous integral winding) may be wrapped with a film on which electrodes are not vapor-deposited, or in order to maintain the insulation properties of the cut surface of the multilayer capacitor. The cut surface is coated with lacquer or adhesive is coated to maintain the unity of the elements. - No element processing (about 1 or less)
Even if it is, it goes without saying that it is still within the scope of what we are talking about here.

-ζ゛, P When the capacitor of the present invention is used in combination with a chip capacitor, that is, when it is used in combination with a chip capacitor, that is, when the capacitor is used in combination with a chip capacitor, 1.・Mount by directly attaching the electrode lead-out member to the circuit conductor with solder, without providing lead wires or providing holes on the circuit board for inserting the lead wires (hereinafter, such mounting method will be referred to as surface mounting). abbreviated as law2
is most useful when

□～ξ ・ In the present invention, the end face of a capacitor is defined as the end face perpendicular to the winding axis when the vapor-deposited film is wound (in the case of a laminated capacitor, the winding axis when simultaneously integrally wound). Refers to the surface.

:,・Next, the method for manufacturing the capacitor of the present invention will be explained.

First, the polyp used in the present invention
- To the phenylene apparatus... As a method for polymerizing sulfide, a method is used in which alkali sulfide and p-di-lobenzene are reacted in a polar solvent at high temperature and high pressure. In particular, it is preferable to react sodium sulfide and p-dichlorobenzene in an amide-based high-boiling polar solvent such as N-methyl-prolidone. In this case, in order to adjust the degree of polymerization, it is most preferable to add a so-called polymerization aid such as a caustic alkali or an alkali metal carboxylic acid salt, and to carry out the reaction at 230°C to 280°C.

The pressure within the polymerization system and the polymerization time are appropriately determined depending on the type and amount of the auxiliary agent used, the desired degree of polymerization, and the like.

To the thus obtained poly-p-phenylene sulfide,
Blend and add other polymers, additives, etc. as necessary.

At this time, in order to improve the surface roughness of the film, poly-p
- 0 to 5 wt% of polymers other than phenylene sulfide
It is preferable to add (more preferably 0.3 to 3 wt%).

An example of such an additive polymer is polyethylene.

Polypropylene, ethylene, propylene copolymer, polystyrene, polysulfone, bolyete 2
``S'' Hong 4F' conversion 1ch > 7°67y Ihi 7°
.

・□゛ Examples include pyrene copolymer, polyamide, etc.□.

The resin composition (PPS) thus obtained is supplied to a well-known melt extrusion device such as an extruder,
The melted resin is then cut by 95% with a hole diameter of 3 to 20.
High precision of μm (preferably 3 to 15 μm)
After filtering with a filter, so-called T-die or 2
Continuously extruded from ゛ゝ onto a cooled metal drum [;,.

Cast, rapidly solidified, and in an unoriented amorphous state]
Make it a sheet. The surface of the metal drum is 1. Roughness□2.1.・It is preferable that the force be 48 or less and 0 mirror surface.

' Next, the sheet thus obtained is biaxially stretched. As the stretching method, well-known methods such as sequential biaxial stretching method and simultaneous biaxial stretching method can be used, but after stretching the sheet in the longitudinal direction by a group of rolls,
So-called vertical and horizontal sequential 2 stretching in the width direction by a denta
Preferably, the axial stretching method is used. The stretching temperature is 95 in both length and width.
The temperature should be in the range of ~110°C. On the other hand, the stretching ratio is determined by the resin viscosity,
It varies depending on the stretching temperature, etc. - Although it cannot be generalized, it is approximately 3.2 to 4.5 times in the longitudinal direction and approximately 3.0 to 3 times in the transverse direction.
．． 8 times the range.

Next, the stretched film thus obtained is subjected to fixed length heat treatment. The constant length heat treatment here means that the change in width and length during heat treatment is 10% or less. The heat treatment conditions are 250-290°C for 1-20 seconds, but preferably 260-285°C for 3-20 seconds.

After the constant length heat treatment, relaxation is performed at a temperature of 240 to 290°C. The relaxation rate of the deposited PP5-B
The heat shrinkage rate at 250°C in the longitudinal and width directions of O is controlled to be within the above range, and the control range is 4 to 10% in the width direction and 0 to 6% in the longitudinal direction.
That's about it.

In the manner described above, a biaxially oriented PPS film is obtained.

A thin metal film to serve as an electrode is formed on the surface of the film thus obtained by a method such as vacuum evaporation to form a so-called metallized film. A capacitor element is formed from the metallized film by a known method such as winding or laminating. After that, 200
It is preferable to heat at a temperature of .degree. C. to 250.degree. C. and press in a direction perpendicular to the winding axis.

When forming a metal thin film layer on a film, it is preferable to subject the film surface to a surface treatment such as corona treatment or plasma treatment in advance.

゛ Both end faces of the capacitor element thus obtained are subjected to an end face conductive treatment. For this treatment, it is preferable to use a high melting point metallic compound, a thermosetting conductive paste, or the like.

Although the conductivity-treated portion may be used as an electrode lead-out member, an electrode lead-out member may be provided on the conductivity-treated portion if necessary.

In any case, the electrode lead-out member is made of a material that does not melt at 260° C., and covers all of both end faces and a part of the lower face. At this time, it goes without saying that the electrode lead-out members covering each end face must be insulated from each other.

In the manner described above, the capacitor of the present invention can be obtained.

FIG. 1 shows an embodiment of a capacitor 1 of the present invention, in which a capacitor element 2 includes a dielectric 3 made of laminated PP5-BO films and an electrode made of a vapor-deposited metal thin film between the dielectric 3. It is formed from 4. A metallicon layer 5.5' is provided on both end surfaces of the capacitor element 2, and an electrode lead member 6 is further provided on this metallicon layer.
, 6' are provided.

Such a capacitor l of the present invention has an appearance as shown in FIG. In FIG. 2, 7.degree. 7' indicates the end surface side of the capacitor element 2, and 8 indicates the bottom surface.

〔Effect of the invention〕

The capacitor of the present invention has the above configuration, and as a result,
When mounted as a chip capacitor on a circuit board using the surface mounting method, it can be mounted without any restrictions under normal /% soldering equipment and conditions, regardless of whether it is a reflow one-way method or a dip method, and there is no change in capacitance at that time. It has excellent characteristics that could not be achieved with conventional film capacitors, such as extremely small reductions in insulation resistance and withstand voltage. Moreover, since the capacitor of the present invention does not have an exterior,
In order to obtain a predetermined capacity, the external dimensions can be made smaller than those with external packaging, so it has the outstanding feature that the packaging density can be increased accordingly. Furthermore, since no exterior is provided, the manufacturing process can be simplified.

In addition, the capacitor of the present invention has an excellent feature that conventional capacitors do not have, in that the capacitance hardly changes even if the temperature and humidity change significantly, so it can always maintain a constant capacitance under changing environments. It is useful for required circuits.

In addition, the capacitor of the present invention has low dielectric loss over a wide temperature range and exhibits stable characteristics for a long time even at temperatures as high as 100 to 170 degrees Celsius, so it can be used in situations where the surroundings are exposed to high temperatures, such as inside automobiles or electrical equipment. Suitable for use anywhere.

Next, methods for measuring and evaluating the characteristic values of the film and capacitor used in the description of the present invention will be explained.

(1) Heat shrinkage rate of film A film of initial length A was heated at 250°C in a hot air oven.
When the length after heating for 10 minutes is B, 100
The heat shrinkage rate (%) is defined by x (A-B) /A.

(2) Capacitance of capacitor using automatic capacitance bridge, 25'C, lK
Capacitance was measured with H2.

(3) Insulation resistance The insulation resistance value was determined from the current flowing when 50 V DC was applied between the electrodes.

(4) Solder heat resistance test Solder heat resistance was evaluated based on the rate of change in characteristic values after immersion in a 250° C. solder bath for 10 seconds with respect to initial characteristics. It goes without saying that the smaller the change, the better the solder heat resistance.

Example 1 (1) Preparation of biaxially oriented polyphenylene sulfide film (PPS-BO) used in the present invention 32.6 kg of sodium sulfide (250 mol, 40 w of crystal water) was placed in an autoclave.
100 g of sodium hydroxide, 36.1 kg (250 mol) of sodium benzoate, and N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) 79.
After preparing 2 kg and making it hydrophilic with 205, 37.5 kg of l,4 dichlorobenzene (abbreviated as p-DCB) (2
55 mol) and 20.0 kg of NMP were added, and 265
The reaction product reacted at ℃ for 3.5 hours was washed with water and dried to obtain 21.1 kg of poly-roof unilene sulfide consisting of 7,100 mol% of p-phenylene sulfide and having a melt viscosity of 2,500 voids (yield: 78%). ) was obtained.

This composition contains 0.3 wt% of calcium carbonate fine powder with an average particle size of 2.0 μm, and 0.0% of calcium stearate.
5 wt% was added, melted at 310°C using an extruder with a diameter of 40 se+m, filtered through a filter with a 95% cut pore size of 10 μ-, and then filtered with a length of 400 ms and a gap of 1.
Extruded through 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 31 μm.

This film is stretched by a longitudinal stretching device consisting of a group of rolls.
Film temperature 100°C, stretching speed 20.000%/wi
longitudinally stretched 3.6 times at n, and then using a tenter at a temperature of 1
00°C, stretching speed 1, 3.4 times transverse stretching at 500%/sin, and 275°C in a subsequent heat treatment chamber in the same tenter.
A fixed length heat treatment was performed for 5 seconds.

Furthermore, in a relaxation chamber following the heat treatment chamber in the same tenter, relaxation was performed by narrowing the tenter rail width by 7% for 5 seconds at a temperature 10°C lower than that of the heat treatment, and P'PS with a thickness of 2.5 μl was -BO was obtained (referred to as film A).

(2) Preparation of capacitor The above film A was placed in a vacuum evaporator and zinc was evaporated on one side to give a surface resistance of 2.5Ω. At this time, by the tape margin method, the width of the evaporated part was 8.0 vw, and the width of the non-evaporated part was 1.0 vw. It was deposited in stripes so that it became Ota-. This vapor-deposited film was slit by inserting a blade into the center of each of the vapor-deposited and non-evaporated areas to obtain a pair of two types of slit films with a width of 4.5 mm and a margin of 0.5 aai on the right or left side. Ta. This is applied to an element winding machine, and a pair of two types of films are wound in the same direction in a layered manner.
After preheating in an oven at 230° C. for 10 minutes, the hollow portion was crushed by pressing, and both end surfaces were treated with metallicon by a conventional method. Further, metal caps made of copper plated with nickel were separately placed on both end faces of the metallcon as electrode lead-out members to obtain a capacitor of the present invention (capacitance: 0.15 μF). The element of this capacitor before metallicon treatment was rewound and heated to 250℃.
The heat shrinkage rate for 10 minutes was 1.9% in the longitudinal direction.
2 width direction was 0.2%.

(3) Evaluation Table 1 shows the evaluation results of the capacitor obtained.6 Although the capacitor of the present invention has no exterior and is extremely small, the capacitance change due to heat during soldering is extremely small. , it can be seen that it has excellent solder resistance.

(Margins below this page) Table 1 (Measurements were made on 10 pieces and the arithmetic average was taken) Example 2 (Preparation of 11P P S -BO In the same manner as film A in Example 1, heat treatment at constant stretching ratio 4 types with different temperatures and relaxation rates0) PPS-BO
(thickness 4#11) was prepared (referred to as film B-E)
.

(2) Creation and evaluation of capacitors In the same manner as in Example 1, only the preheating temperature of the press was changed as shown in Table 2, and films B to E were each used as a dielectric material.
Types of unpackaged chip capacitors (each capacitor B-E
) was created.

Table 2 shows the evaluation results of the capacitors created.From this table, capacitors whose heat shrinkage rate of the metallized film is within the range described in the present invention have good solder heat resistance as chip capacitors without packaging. It is clear that it has a sexual nature.

(Margins below this page)

[Brief explanation of the drawing]

:"1j((i,g) Figure 1 is a cross-sectional view showing an embodiment of the capacitor of the present invention (J'Mi1), and Figure 2 is a perspective view of its external appearance. ・'i・'1 010.17 A7+, 200
．． Yo, a, Kamoko, 30. . □j゛;1 ・. (・i;, dielectric, 4...electrode, 6
...Electrode extraction member. ：；ze、、′：゛： Agent Patent attorney Nobuo Ogawa −゛・、Patent attorney Ken Teru Noguchi、□zo

Claims (1)

[Claims] A capacitor in which the main dielectric is made of a biaxially oriented film of a resin composition containing poly-p-phenylene sulfide as a main component, and the electrode is made of a metal thin film deposited on the surface of the dielectric film. °C, 1
The heat shrinkage rate for 0 minutes is 0 to 6% in the longitudinal direction of the film, -2 to 2% in the width direction, and
A capacitor characterized in that an electrode lead-out member that does not melt at 60° C. is provided, the member covers all of both end faces and a part of the lower surface of the capacitor, and the capacitor is substantially without an exterior.