JPH04218573A - Polymer-type dielectric paste - Google Patents

Abstract

PURPOSE:To provide an organic dielectric paste having high dielectric constant and excellent heat-resistance and waterresistance. CONSTITUTION:The objective organic dielectric paste contains a thermosetting resin and an organic electron acceptor as essential components. A reaction product of a polyalkylene glycol and an organic electron acceptor may be used in place of the organic electron acceptor. The paste may be incorporated with ferroelectric inorganic powder and carbon powder.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric paste containing an organic vehicle as a binder and having a high dielectric constant and excellent heat resistance and water resistance.

0002

[Prior Art] Dielectric paste refers to a paste that forms a dielectric layer by screen printing and then firing, and is broadly divided into inorganic pastes using glass frit as a binder and organic pastes using an organic vehicle as a binder. There is. Inorganic dielectric paste has traditionally been used as an insulating coating to protect electronic components and circuits such as resistors and capacitors, and as a thick film dielectric layer for separating and insulating upper and lower conductors in thick film multilayer circuits. Alternatively, for applications such as dielectric films for thick film capacitors, glass powder or ceramic dielectric powder has been dispersed in a solvent, screen printed, and then fired at high temperatures for practical use.

On the other hand, organic dielectric paste can be put into practical use mainly for dispersed EL applications and capacitor applications by dispersing ceramic dielectric powder in an organic vehicle and drying it at a low temperature from room temperature to about 25°C or less. It is being In particular, in dispersed EL applications, technological improvements such as larger LCDs, higher resolution, improved visibility, and full-color LCDs are progressing rapidly, and with the growth of electroluminescent lamps used as backlights, organic The need for dielectric pastes is increasing.

[0004] In this application, high brightness and long life of the element are required. This requires a coating film formed from an organic dielectric paste to have a high dielectric constant and good water resistance. In response, an organic dielectric paste has been developed in which dielectric powder is dispersed in a cyano group-containing compound having a high dielectric constant. For example, Japanese Unexamined Patent Publication No. 1-200595 discloses a paste consisting of an organic high dielectric material and a compound capable of radiation polymerization as a phosphor powder for EL. Further, Japanese Patent Application Laid-Open No. 1-166408 discloses a paste in which high dielectric constant ceramics are dispersed in an acrylic binder. However, none of them has been able to overcome the problems of heat resistance and water resistance while maintaining the above-mentioned high dielectric constant.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a low-temperature drying paste that has a high dielectric constant, water resistance, and heat resistance.

[0006]

[Means for Solving the Problems] The present inventors have conducted intensive research to solve these drawbacks and obtain a low-temperature drying paste that has high dielectric constant, water resistance, and heat resistance. Reached.

That is, the present invention is: (1) A polymer type dielectric paste containing a thermosetting resin and an organic electron acceptor as essential components. In addition, (2) instead of the organic electron acceptor, a good paste can be obtained by using a polymer type dielectric paste containing a reaction product of polyalkylene glycol and an organic electron acceptor as an essential component. Furthermore,■
The present invention relates to a polymer dielectric paste containing a thermosetting resin, a ferroelectric inorganic powder, and an organic electron acceptor as essential components. Also, (1) By adding carbon powder to this paste, an even higher dielectric constant can be obtained.

The present invention will be explained in detail below. The thermosetting resin used as an organic vehicle in the present invention refers to a resin that can be cured by heat, light, electron beams, or the like. Specific examples include so-called thermosetting resins such as phenolic resin, melamine resin, urea resin, unsaturated polyester, epoxy resin, polyurethane, silicone resin, addition type polyimide, DAP resin, and thermosetting acrylic resin; radical polymerization ,
Monomers, oligomers or polymers with unsaturated bonds capable of addition polymerization, such as ionic polymerization, such as styrene,
Examples include divinylbenzene, (meth)acrylic acid and its esters, polyallyl polymeritate, triallyl isocyanurate, and the like. Preferably, it is an epoxy resin with good water resistance. More preferred is an epoxy resin using polyoxytetramethylene oxide di(para-aminobenzoate) as a curing agent.

Typical polyalkylene glycols used in the present invention are polyethylene glycol and polypropylene glycol. The ferroelectric inorganic powder used in the present invention is LiTaO3, LiNbO3
, single crystals such as α-SiO2, PZT, PbT
It is a polycrystalline material such as iO3 or BaTiO3, and generally has a high dielectric constant. Preferred is BaTiO3
It is.

[0010] The particle shape of the ferroelectric inorganic powder is not particularly limited, and various shapes such as spherical and rod shapes can be used. Furthermore, particles having an average particle diameter of 0.1 to 50 μm can be used. Preferably 1 to 10 μm
It is. Furthermore, two types of powders having different particle size distributions may be mixed.

The organic electron acceptors used in the present invention include 7,7,8,8-tetracyanoquinodimethane (hereinafter abbreviated as TCNQ), tetracyanoethylene, 2-
Methyl-7,7,8,8-tetracyanoquinodimethane, 2,5-dimethyl-7,7,8,8-tetracyanoquinodimethane, 2,3,5,6-tetrafluoro-7,
Examples include 7,8,8-tetracyanoquinodimethane, quinhydrone which is an intermediate between hydroquinone and benzoquinone, other quinones, and Lewis acids such as trinitrobenzene. Preferred is TCNQ.

[0012] The reaction product of polyalkylene glycol and organic electron acceptor as used in the present invention is mixed at room temperature to 200°C in an amount of 0.1 to 2 moles of organic electron acceptor per mole of polyalkylene glycol. obtained by Preferred is the reaction product of polyethylene glycol and tetracyanoethylene.

Examples of the carbon powder that can be added in the present invention include graphite; carbon blacks such as acetylene black, thermal black, furnace black, and channel black. Carbon powder having an average particle diameter of 0.01 to 50 μm can be used. A preferable carbon powder has an average particle size of 1 to 20 μm.
graphite.

The dielectric paste of the present invention is obtained by mixing the above thermosetting resin, ferroelectric inorganic powder, and organic receptor. Although the mixing ratio of each component is not limited, the following composition is preferred. (1) Thermosetting resin 80-99% by weight (
2) Organic electron acceptor 1 to 20% by weight If the content of the organic electron acceptor is more than 20% by weight, the mechanical performance of the resulting coating film will be insufficient and the electrical properties will also deteriorate, while if it is less than 1% by weight, it will not have good dielectric properties. Characteristics cannot be obtained. The preferred range is 5
~10% by weight.

[0015] Furthermore, a reaction product of polyalkylene glycol and an organic electron acceptor (simply,
When adding a reaction product), the following composition is preferred. (1) Thermosetting resin 20-80% by weight (
2) Reaction product 80-20% by weight If the reaction product is more than 80% by weight, a good coating film cannot be obtained, and if it is less than 20% by weight, good dielectric properties cannot be obtained.

Furthermore, when a dielectric paste is prepared using ferroelectric inorganic powder, the following composition is preferred. (1) Thermosetting resin 5-50% by weight
(2) Ferroelectric inorganic powder 0.1-10% by weight
(3) Organic electron acceptor 0.1-10% by weight

If the thermosetting resin is less than 5% by weight, the mechanical performance of the resulting coating film will be insufficient and the electrical properties will also deteriorate.
If it exceeds 50% by weight, good dielectric properties cannot be obtained. If the ferroelectric inorganic powder is less than 50% by weight, good dielectric properties cannot be obtained, and if it is more than 95% by weight, the mechanical performance of the coating film is insufficient and the electrical properties are also deteriorated. Organic electron acceptor is 0.
If it is less than 1% by weight, good dielectric properties cannot be obtained, and if it is more than 10% by weight, the water resistance of the coating film is impaired. The preferred range is 0
．． It is 5 to 5% by weight.

Further, it is preferable that the amount of carbon powder added is 10% by weight or less. If it is more than 10% by weight, the dielectric loss tangent of the coating film will deteriorate. The preferred amount is 2 to 6% by weight.

The dielectric paste of the present invention may contain various additives as necessary, such as various solvents such as cellosolve, carbitol, and esters to impart printability to the paste of the present invention, and leveling agents. , a thixotropic agent, an antifoaming agent, and various fillers such as silica, alumina, and talc may be added.

[0020] The method of mixing each component for producing the paste of the present invention is not particularly limited. When using ferroelectric inorganic powder and carbon powder, any method that can sufficiently disperse them may be used. For example, it is manufactured using equipment such as a roll or a peeler. When mixing the organic electron acceptor, it is desirable to dissolve it in a solvent or a thermosetting resin before thermosetting and then mix it.

The paste of the present invention can be applied to an adherend such as a substrate to form a pattern using a commonly used coating machine such as screen printing to obtain a desired coating film. This coated adherend is heated or
A desired dielectric layer can be formed by irradiating V and electron beams. The polymer dielectric paste of the present invention can be used for forming electronic circuits such as distributed EL and capacitors.

[0022]

EXAMPLES The present invention will be explained in more detail below based on examples, but these do not limit the scope of the invention.

[Example 1] Bisphenol A epoxy resin AER
331 (manufactured by Asahi Kasei Industries, Ltd.), 45 parts by weight of polyoxytetramethylene oxide di(para-aminobenzoate) and 10 parts by weight of a modified aromatic amine, and then tetracyanobenzene (hereinafter referred to as TCNB)
A dielectric paste 1 was obtained by adding 6 parts by weight of the paste and thoroughly stirring until it became uniform.

[0023] This paste was applied with a brush onto a copper-clad glass/epoxy resin laminate substrate to a coating thickness of approximately 500 μm, and after degassing in vacuum, it was baked and cured for 90 minutes at 160°C. Ta. On the epoxy dielectric film obtained in this way, electrodes made of carbon conductive paint were screen printed to evaluate the electrical properties of the film (
diameter 20mm, film thickness 30μm), 10% in an atmosphere of 150℃
A drying operation was performed for several minutes to prepare a sample for measurement.

As for the dielectric properties of the sample, the dielectric constant at a frequency of 1 KHz was measured at 20° C. and found to be 14.5. When this coating was left in a high-temperature atmosphere of 100° C. for 1,000 hours, there was no abnormality in appearance and almost no change in electrical properties. Furthermore, when the same coating was left in an atmosphere of 60°C/95RH% for 1,000 hours, there was no abnormality in appearance and almost no change in electrical properties.

[0025]

[Example 2] [Synthesis of reaction product] Average molecular weight 1,00
0.5 mol of tetracyanoethylene was mixed with 1 mol of polyethylene glycol of 0.0 and reacted at 160° C. for 48 hours to obtain reaction product 1. [Preparation of dielectric paste] 30% by weight of bisphenol F-type epoxy resin Epicoat 807 (manufactured by Yuka Shell Epoxy Co., Ltd.), 20% by weight of modified aromatic amine, and 50% by weight of reaction product 1 were thoroughly mixed to form a dielectric paste. Body paste 2 was prepared. Using this paste, performance was investigated in the same manner as in Example 1, and the dielectric constant was 15.8 and the dielectric loss tangent was 0.79.

[0026]

[Example 3] 12 parts by weight of melamine-modified epoxy resin (a mixture of methylol melamine resin and bisphenol-type epoxy resin with an epoxy equivalent of 1,500 in a ratio of 7:3; hereinafter abbreviated as ME) has an average particle size of 7 μm. Ba of
TiO3 powder (relative dielectric constant 17,000) 88 parts by weight, T
0.3 parts by weight of CNQ was added and mixed well, and the viscosity was further adjusted with butyl carbitol and uniformly dispersed in an automatic mortar to obtain dielectric paste 3.

This dielectric paste was screen printed on the copper foil surface of a copper-clad paper phenolic resin laminate board to a film thickness of approximately 50 μm, and after degassing in vacuum, it was baked and cured at 160° C. for 30 minutes. It was dried. This printing and drying operation was repeated once more to finally obtain a coating film with a thickness of about 100 μm. Further, in order to evaluate the electrical properties of the dielectric film, a copper-based conductive paint (diameter: 20 μm, film thickness: 30 μm) was screen printed, and baked and hardened under the same conditions as the dielectric paste. The dielectric constant and dielectric loss tangent of the dielectric coating film thus obtained were measured at 20° C. and a frequency of 1 KHz. The results are shown in Table 1.

[0028]

[Table 1]

[0029] Also, the obtained coating film was heated at 60°C/95RH%.
After being left in an atmosphere of 1,000 hours, there was no abnormality in appearance and almost no change in electrical characteristics.

[0030]

[Examples 4 to 6] Table 2 shows the materials used in Example 3.
Dielectric pastes 4 to 6 were prepared by changing the composition as shown in
I got it. A coating film was produced in the same manner as in Example 3. The electrical properties of the obtained coating film are also shown in Table 2. The blending ratios in the table are parts by weight.

[0031]

[Table 2]

[0032]

Examples 7 to 9 In addition to the materials used in Example 3, carbon graphite was further added as shown in Table 3 to obtain dielectric pastes 7 to 9. A coating film was produced in the same manner as in Example 3. The electrical properties of the obtained coating film are also shown in Table 3. The blending ratios in the table are parts by weight.

[0033]

[Table 3]

[0034]

Comparative Example 1 A paste was prepared in Example 1 without using TCNB. A coating film was prepared using the paste in the same manner as in Example 1, and its electrical properties were examined. As a result, only a dielectric constant of 5.2 was obtained.

[0035]

[Comparative Example 2] In Example 3, a paste was prepared without using TCNQ. A coating film was prepared using the paste in the same manner as in Example 3, and its electrical properties were examined. As a result, only a dielectric constant of 65 was obtained.

[0036]

[Effects of the Invention] According to the present invention, it has a high dielectric constant, heat resistance,
An organic dielectric paste with excellent water resistance can be obtained.

Claims (4)

[Claims] 1. A polymer dielectric paste containing a thermosetting resin and an organic electron acceptor as essential components. 2. A polymer-type dielectric paste containing a thermosetting resin, a reaction product of polyalkylene glycol, and an organic electron acceptor as essential components. 3. A polymer dielectric paste containing a thermosetting resin, a ferroelectric inorganic powder, and an organic electron acceptor as essential components. 4. A polymer-type dielectric paste containing a thermosetting resin, a ferroelectric inorganic powder, an organic electron acceptor, and a carbon powder as essential components.