JP2803276B2 - Multilayer film chip capacitors - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-heat-resistant and low-hygroscopic laminated film chip capacitor used for electronic equipment and electric equipment.

Conventional technologyPoly 2,6-dimethylpolyphenylene oxide has a high thermal deformation temperature of 190 ° C and a low dielectric loss of 0.001 at a frequency of 1 KHz. It has been widely used as a dielectric material. The applicant has proposed a laminated film chip capacitor as one of the uses.

The outline of this laminated film chip capacitor will be described.

First, aluminum is vacuum-deposited on both sides of a plastic film made of polyphenylene sulfide to form a deposition electrode. On this deposition electrode, a dielectric layer made of poly 2,6 dimethyl polyphenylene oxide is formed by a coating method of a paint dissolved in a chlorine-based organic solvent,
A double-sided, double-sided coated film is obtained. next,
Hundreds of double-sided coated double-sided coating films are laminated, a metallikon layer is formed on the end face of the laminated body, and an electrical connection is made with the deposited electrode, thereby obtaining a mother capacitor.

The mother capacitor is first heated at a temperature in the range of 90-120 ° C. to remove any residual solvent. Furthermore, in order to improve the heat resistance of poly 2,6 dimethyl phenylene oxide which is not sufficient as it is, it is heated for 15 to 150 hours at a temperature in the range of 150 to 190 ° C where its thermal deformation does not occur, and then heated from above and below. After being subjected to a crosslinking treatment by heating at a temperature of 200 ° C. for 1 hour while pressing, the slice is cut into a capacitor element. Comb leads are welded to the metallikon layer of this capacitor element, and after a mold package is applied with epoxy resin, the comb leads are processed to become external electrodes, thereby obtaining a multilayer film chip capacitor.

The multilayer film chip capacitor thus obtained is suitable for reflow soldering with a maximum temperature of 230 ° C, its dielectric loss is 0.0015 at a frequency of 1 KHz, and the capacitance between after drying and after absorbing moisture The characteristic that the rate of increase was 5% was shown. The thermal deformation temperature of the coating dielectric taken out of the completed laminated film chip capacitor was 198 ° C.

Problems to be Solved by the Invention In recent years, in order to reduce the size and performance of electronic devices and electrical devices, and to automate the manufacturing process thereof, the components used in these devices have been reduced in size, performance and chips. The request is very large. This is no exception for film capacitors. For this reason, low hygroscopicity, high heat resistance, and the like have been required for the dielectrics used for them.

Poly 2,6 dimethyl phenylene oxide has the advantage of being easily soluble in a solvent and easy to process, but has insufficient heat resistance. Therefore, in order to compensate for the disadvantage, poly-2,6-dimethylphenylene oxide has been subjected to a cross-linking treatment by performing a heat treatment at a temperature high enough not to cause thermal deformation for a relatively long time. As a result, the methyl group, which is a side chain of poly 2,6 dimethylphenylene oxide, has an OH group due to oxidation, thereby increasing the hygroscopicity, and the poly 2,6 dimethyl phenylene oxide after drying and after absorbing moisture It was apparent that the relative permittivity between 1 and 2 originally increased by about 1%, but apparently increased by 9% and changed. The apparent increase in relative permittivity between after drying and after moisture absorption is due to the fact that the relative permittivity of poly 2,6 dimethylphenylene oxide is 2.6, while the relative permittivity is 80.
And a very large amount of water in a fraction of a percent
It is presumed to be caused by intrusion into 6-dimethylphenylene oxide.

In order to solve the problem of apparent relative dielectric constant increase or insufficient heat resistance due to such moisture absorption, poly 2,6-dimethylphenylene oxide has low moisture absorption similar to that before heat treatment, and the same as after heat treatment. It is easily conceivable to use a polymer compound having a heat distortion temperature of about or higher. However, there are very few polymer materials having a high heat distortion temperature that are soluble in solvents. In recent years, the development of polymer compounds has become active,
Polyarylates that are easily soluble in solvents but have a heat distortion temperature exceeding 230 ° C. have been developed. However, analysis of the infrared absorption spectrum of the polyarylate revealed that it had unreacted OH groups. The apparent relative dielectric constant increase rate due to moisture absorption reached 6 to 10%, which was a major problem.

An object of the present invention is to provide a laminated film chip capacitor having high heat resistance and low moisture absorption by using a polymer compound having these OH groups and eliminating the OH groups by a chemical reaction.

Means for Solving the Problems The laminated film chip capacitor of the present invention uses a dielectric material obtained by adding methylhydrogenpolysiloxane and diisoproxybis (acetylacetonato) titanium to a polymer compound having an OH group. It is characterized by the following.

Action Polyarylate has an ester bond in the main chain and has a hydroxyl group or a carboxyl group at the terminal. It is presumed that polyarylate has high hygroscopicity due to OH groups derived from these.

The present invention relates to a polymer compound having an OH group such as methyl hydrogen polysiloxane and diisopropoxy.
By adding bis (acetylacetonato) titanium and performing heat treatment, OH groups and these additives chemically react to form O-Si bonds or O-Ti bonds, or polymer compounds having OH groups A three-dimensionally crosslinked organometallic compound layer having extremely low moisture permeability is formed in the vicinity of the surface of a dielectric layer made of, and the rate of increase in apparent dielectric constant due to moisture absorption can be significantly reduced to 2 to 3%. It is.

Since methyl hydrogen polysiloxane is a liquid, when added alone to a polymer compound, it significantly lowers the heat distortion temperature of the polymer compound. However, in this case, by adding diisopropoxy bis (acetylacetonato) titanium in combination, the reaction occurs at a low temperature below the lowered heat distortion temperature and the crosslinking proceeds, thereby increasing the heat distortion temperature. I do. As a result, it was possible to prevent a decrease in the heat distortion temperature due to the addition of methyl hydrogen polysiloxane, and to obtain a favorable result that the heat distortion temperature of the original polymer compound was improved after all the chemical reactions were completed.
The effect of reducing OH groups by adding diisopropoxy bis (acetylacetonato) titanium alone was incomplete because the amount of addition and heat treatment conditions were strongly affected, and conversely OH groups increased.

Examples Hereinafter, the present invention will be described based on examples.

Example 1 A plastic film made of polyphenylene sulfide having a thickness of 2 μm was coated with aluminum to a thickness of 400 on both sides.
An electrode was formed by vapor deposition on Å.

Then, 10% by weight of methyl hydrogen polysiloxane and 5% are added to the polyarylate having the structure shown above.
A weight percent of diisopropoxy bis (acetylacetonato) titanium is dissolved in a chlorine-based organic solvent, and a sufficiently stirred coating solution is applied to a thickness of 1 μm on the double-sided electrode to form a dielectric layer. A vapor-deposited double-sided coating film was obtained. Next, several hundreds of the double-sided vapor-deposited double-sided coating films were laminated, and zinc was sprayed on the end face of the obtained laminated body to form a metallikon layer, thereby obtaining a mother capacitor.

After gradually raising the temperature of the mother capacitor within the range of 90 to 120 ° C., a heat treatment was performed by heating at a temperature of 160 ° C. for 10 hours and further at a temperature of 200 ° C. for 1 hour while applying pressure from above and below. After the heat treatment, the mother capacitor was sliced to obtain a capacitor element, and a comb lead was welded to a metallikon layer of the obtained capacitor element. Then, after applying a mold exterior with an epoxy resin, the comb leads were processed into external electrodes to obtain a multilayer film chip capacitor.

Example 2 0.5% by weight of methyl hydrogen polysiloxane and 0.5% by weight of polyarylate having the structure shown in Example 1
A multilayer film chip capacitor was obtained in the same manner as in Example 1 by using a coating solution obtained by dissolving weight percent of diisopropoxy bis (acetylacetonato) titanium in a chlorine-based organic solvent and sufficiently stirring.

Example 3 20% by weight of methylhydrogenpolysiloxane and 40% by weight of diisopropoxybis (acetylacetonato) titanium were dissolved in a polyarylate having the structure shown in Example 1 in a chlorine-based organic solvent and thoroughly stirred. A multilayer film chip capacitor was obtained in the same manner as in Example 1 using the above coating liquid.

As a comparative example, a multilayer film chip capacitor was obtained in the same manner as in Example 1 except that the polyarylate having the structure shown in Example 1 was dissolved alone in a chlorine-based organic solvent and a sufficiently stirred coating liquid was used.

As a conventional example, a laminated film chip capacitor was obtained in the same manner as in Example 1 using a coating solution in which poly 2,6-dimethylphenylene oxide was dissolved alone in a chlorine-based organic solvent and sufficiently stirred.

Using the laminated film chip capacitors of the present invention, the comparative example, and the conventional example obtained as described above, each of which is 50 pieces, the average between the time after drying and the time when the temperature is left in an atmosphere of 40 ° C. and 95% humidity and sufficiently absorbed is obtained. The following table shows the capacitance increase rate and the thermal deformation temperature of the dielectric layer taken out of the multilayer film chip capacitor.

As is apparent from these results, according to the present invention, the rate of increase in capacitance due to moisture absorption can be significantly reduced, characteristics can be improved, and the heat distortion temperature can be improved, so that heat resistance can be improved.

Further, in the present invention, the polymer compound is not limited to the polyarylate shown in the above examples, and is not related to the number of methyl groups in the side chain and the sulfonyl group in the main chain is a methylene group, an ether group or a sulfide group. The same good results as in the above example were obtained for Similar good results were obtained with polyethersulfone and polyetherimide. Similar effects were also observed with cyanoethylated hydroxyethyl cellulose and cyanoethylated pullulan having OH groups in the chain measurement.

Also in the laminated film chip capacitor in which the final temperature of the heat treatment was 230 ° C. or higher and the mold exterior was omitted, a favorable result was obtained in which the rate of increase in capacitance due to moisture absorption was 2.5% or less.

In addition, regarding the characteristics of dielectric loss and insulation resistance, good results were obtained without any problem such as increase or decrease even when the heat treatment was performed by adding an organometallic compound.

Effects of the Invention According to the present invention, methylhydrogenpolysiloxane and diisopropoxybis (acetylacetonato) titanium are added to a polymer compound having an OH group in combination, and the hygroscopicity is significantly reduced by heat treatment. In the multilayer chip capacitor using this as a dielectric, the rate of increase in capacitance due to moisture absorption became small, and the capacitance became extremely stable. At the same time, the thermal deformation temperature of the coating dielectric can be dramatically improved, and the soldering operation can be performed under a wide range of temperature conditions regardless of the solder flow method or the reflow method.

Another effect of the additives is to improve the surface tension and fluidity of the paint, to improve the uniformity of the coating by the coating method, to improve the slipperiness, to make the production stable, and to improve the yield, It is possible to improve reliability and reduce costs.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-14866 (JP, A) JP-A-1-130515 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01 4/00-4/40

Claims (1)

(57) [Claims] 1. A plastic film, comprising: a vapor deposition electrode formed on both surfaces of the plastic film; and a dielectric layer formed on at least one surface of the vapor deposition electrode, wherein the dielectric layer has at least 0.5% to 20% by weight of methyl hydrogen polysiloxane and 0.5% to 40% by weight of diisopropoxy bis (acetylacetonato) titanium A laminated film chip capacitor comprising a dielectric material added.