JP7495862B2 - Protective coating for electronic materials - Google Patents

Description

The present invention relates to a coating agent for protecting electronic materials.

Many electronic components, including capacitors and inductors, are designed to pass electric current, so metals are used for most of the components. This is because metals have a much smaller electrical resistance than organic resins such as plastics and ceramics, so there is less loss of electrical energy due to heat generated when electric current is passed through them. However, many metal materials react with moisture and sulfides in the environment in which they are used, causing chemical reactions such as oxidation and sulfurization. The metal oxides and metal sulfides generated at this time have various properties, such as electrical properties that are important when used as electronic materials, that deteriorate compared to the original metal, causing defects. In addition, rust generated by oxidation and sulfurization can grow and cause migration, which electrically connects conductive parts. Migration causes a short circuit when electric current is passed through it, which is a very serious problem because it can lead to failure not only of the electronic part that has migrated but also of the entire electronic device.

To solve these problems, a common solution is to protect the surface of electronic components with a coating. The purpose of the coating varies depending on the type of material used and its application, but it mainly prevents oxidation and sulfurization by introducing a gas barrier layer and short circuits by introducing an insulating layer. Conventionally, coatings using organic resins or silicone resins have been used, but organic resins have low heat resistance, so they decompose or change during the reflow process when mounting electronic components on equipment, which causes the coating to fail. In addition, although silicone resins are superior to organic resins in terms of heat resistance, they have insufficient gas barrier properties, making it difficult to meet the characteristics required for a coating. Therefore, deposition and sputtering using inorganic materials such as corrosion-resistant metals and ceramics are used as methods that achieve both gas barrier performance and heat resistance. However, these methods are not only time-consuming to process, but are also very expensive, so they can only be used for high-grade products or special applications.

On the other hand, glass film coating is a relatively easy method for inorganic materials. This is a method in which a solution containing a glass precursor is directly applied to the parts of electronic components that need to be protected, and then a hardening process is performed to create a glassy coating. This method is suitable for mass production because it can be completed in a short time and at low cost compared to inorganic processing methods such as vapor deposition and sputtering. However, silicon alkoxides such as tetraethoxysilane (TEOS) are commonly used as glass precursors, and heat treatment at about 300°C is required to obtain a glassy coating film, which may lead to a decrease in various properties depending on the type of electronic component. Curing at a lower temperature is possible by adding a catalyst, but the solvent and the large amounts of water and alcohol generated during curing remain in the film, resulting in poor film quality and no gas barrier performance.

Therefore, the use of polysilazane has been proposed as a method that can be easily coated in a solution like sol-gel glass using TEOS and has excellent gas barrier properties (for example, Patent Document 1). In particular, perhydropolysilazane (PHPS), which is called inorganic polysilazane, becomes a silica glass film that does not contain organic groups after curing, and the desorbed components hydrogen and ammonia are all gaseous at room temperature and pressure, so they are unlikely to remain in the system, and therefore the gas barrier performance is much higher than that of sol-gel glass formed at low temperatures. On the other hand, due to its very dense structure, it has poor crack resistance, and cracks may occur even in a film thickness of about 1 μm due to residual stress generated by the curing contraction of the PHPS polymer itself. Even if cracks do not occur during curing, cracks may occur during the reflow process when mounting electronic components or due to heat generated by passing electricity through electronic devices. This is due to the difference in linear expansion coefficient between the electronic components coated with glass and the glass coating. In particular, copper, which has high electrical conductivity and is inexpensive, is often used as a material for electronic components, but copper has a high linear expansion coefficient among metals, so the difference with silica glass, which has a low linear expansion coefficient, is large and defects are likely to occur. To solve this problem, a method has been proposed in which polysilazane is modified to introduce organic groups into the glass film, improving crack resistance, but this reduces the essential gas barrier property, making it difficult to strike a balance between these two properties (see, for example, Patent Document 2). A method has also been proposed in which polysilazane is mixed with an organic resin to achieve both gas barrier properties and crack resistance, but this method does not anticipate situations in which high-temperature loads are applied, such as in the reflow process, and issues remain with heat resistance (see, for example, Patent Document 3).

To solve the above problems, there is a need for a coating agent that can be easily applied, has high gas barrier properties and crack resistance, and can maintain sufficient gas barrier performance even after the reflow process.

JP 2011-245625 A JP 2002-293941 A JP 2017-039825 A

The present invention was made in consideration of the above circumstances, and aims to provide a coating agent for protecting electronic materials that has high gas barrier properties, is less likely to crack during curing or at high temperatures, and can be easily applied from a solution.

The present invention has been made to achieve the above object, and provides a coating agent having the following characteristics:

（式中、Ｒ^１は水素原子、または炭素数１～６の脂肪族炭化水素基、炭素数６～１２の芳香族炭化水素基、炭素数１～６のアルコキシ基から選ばれる基である）
で示される繰り返し単位からなり、重量平均分子量が３，０００～５０，０００の範囲内であるポリシラザン化合物、
（Ａ－２）下記式（２）

（式中、Ｒ^２は水素原子、または炭素数１～６の脂肪族炭化水素基、炭素数６～１２の芳香族炭化水素基、炭素数１～６のアルコキシ基から選ばれる基であり、Ｒ^３は炭素数１～６の脂肪族炭化水素基、炭素数６～１２の芳香族炭化水素基、炭素数１～６のアルコキシ基から選ばれる基である）
で示される繰り返し単位からなるポリシラザン化合物、
（Ｂ）有機溶剤
を含む電子材料保護用コーティング剤であり、前記（Ａ－１）成分と前記（Ａ－２）成分との混合比率が、質量比で７／３～３／７の範囲を満たすものである電子材料保護用コーティング剤を提供する。 In the present invention, there is provided a mixture of two polysilazane compounds having different structures, the polysilazane compounds being represented by the following formula (A-1) and (A-2), and a polysilazane compound represented by the following formula (1):

(wherein R ¹ is a hydrogen atom or a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms).
and a weight average molecular weight of the polysilazane compound is within a range of 3,000 to 50,000.
(A-2) The following formula (2)

(In the formula, ^R2 is a hydrogen atom or a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms, and ^R3 is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms.)
A polysilazane compound having a repeating unit represented by the formula:
The present invention provides a coating agent for protecting electronic materials, which contains an organic solvent (B), and the mixing ratio of the component (A-1) to the component (A-2) is in the range of 7/3 to 3/7 by mass ratio.

Such a coating agent for protecting electronic materials has high gas barrier properties, is less likely to crack when cured or at high temperatures, and can be easily applied in solution.

In addition, in the present invention, a coating agent for protecting electronic materials in which the mixing ratio of the (A) component to the (B) component is 0.1/99.9 to 20/80 is preferred.

Such a coating agent for protecting electronic materials is preferable because it has good storage stability and coatability, and can be applied to a large thickness at one time.

In the present invention, a preferred coating agent for protecting electronic materials is one in which R ¹ is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms, and R ² is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms.

Such a coating agent for protecting electronic materials can improve the effects of the present invention.

In addition, in the present invention, the coating agent for protecting electronic materials is preferably one in which the component (A-1) is perhydropolysilazane.

Such a coating agent for protecting electronic materials can improve the film properties after curing.

In addition, in the present invention, the (A-2) component is preferably a coating agent for protecting electronic materials that is monomethylpolysilazane.

Such a coating agent for protecting electronic materials can improve the film properties and crack resistance after curing.

As described above, the coating agent for protecting electronic materials of the present invention is a polysilazane-containing composition that contains at least two types of polysilazanes and an organic solvent, and its high gas barrier properties after curing prevent oxidation and sulfurization of components, making it possible to form a coating film that is less likely to crack during curing or at high temperatures. Therefore, it is possible to obtain a coating agent that can achieve both high gas barrier properties and crack resistance compared to conventional coating agents. In particular, it is possible to maintain the gas barrier properties even after the reflow process.

As mentioned above, there was a need to develop a coating agent for protecting electronic materials that has high gas barrier properties, is less likely to crack when cured or at high temperatures, and can be easily applied from a solution.

As a result of extensive research into the above-mentioned problems, the inventors discovered that a coating agent for protecting electronic materials that contains a mixture of two types of polysilazane compounds with different structures, with a mass ratio of the two compounds being in the range of 7/3 to 3/7, has high gas barrier properties, is less susceptible to cracking during curing or at high temperatures, and can be easily applied in solution, thus completing the present invention.

（式中、Ｒ^１は水素原子、または炭素数１～６の脂肪族炭化水素基、炭素数６～１２の芳香族炭化水素基、炭素数１～６のアルコキシ基から選ばれる基である）
で示される繰り返し単位からなり、重量平均分子量が３，０００～５０，０００の範囲内であるポリシラザン化合物、
（Ａ－２）下記式（２）

（式中、Ｒ^２は水素原子、または炭素数１～６の脂肪族炭化水素基、炭素数６～１２の芳香族炭化水素基、炭素数１～６のアルコキシ基から選ばれる基であり、Ｒ^３は炭素数１～６の脂肪族炭化水素基、炭素数６～１２の芳香族炭化水素基、炭素数１～６のアルコキシ基から選ばれる基である）
で示される繰り返し単位からなるポリシラザン化合物、
（Ｂ）有機溶剤
を含む電子材料保護用コーティング剤であり、前記（Ａ－１）成分と前記（Ａ－２）成分との混合比率が、質量比で７／３～３／７の範囲を満たすものである電子材料保護用コーティング剤である。 That is, the present invention provides: (A) a mixture of two types of polysilazane compounds having different structures, which are represented by the following (A-1) and (A-2); and (A-1) a polysilazane compound represented by the following formula (1):

(wherein R ¹ is a hydrogen atom or a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms).
and a weight average molecular weight of the polysilazane compound having a repeating unit represented by the formula:
(A-2) The following formula (2)

(In the formula, ^R2 is a hydrogen atom or a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms, and ^R3 is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms.)
A polysilazane compound having a repeating unit represented by the formula:
(B) A coating agent for protecting electronic materials, which contains an organic solvent, and the mixing ratio of the component (A-1) to the component (A-2) is in the range of 7/3 to 3/7 in terms of mass ratio.

The present invention is described in detail below, but is not limited to these.

(A) Polysilazane Compound The polysilazane compound used in the coating agent for protecting electronic materials of the present invention is characterized by using a mixture of two or more polysilazane compounds having different structures.

（式中、Ｒ^１は水素原子、または炭素数１～６の脂肪族炭化水素基、炭素数６～１２の芳香族炭化水素基、炭素数１～６のアルコキシ基から選ばれる基である） Polysilazane compounds having different structures are designated as (A-1) and (A-2), and are represented by the following formulas (1) and (2), respectively.
(A-1) The following formula (1)

(wherein R ¹ is a hydrogen atom or a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms).

The polysilazane compound (A-1) is a polysilazane compound consisting of the repeating unit represented by the above formula (1) and having a weight average molecular weight in the range of 3,000 to 50,000. Examples include perhydropolysilazane, which is an inorganic polysilazane, or modified polysilazanes such as methylpolysilazane, phenylpolysilazane, vinylpolysilazane, methoxypolysilazane, and ethoxypolysilazane, hydrocarbon compounds having reactive groups such as hydroxyl groups, vinyl groups, amino groups, and silyl groups that chemically react with polysilazane to form a crosslinked structure, cyclic saturated hydrocarbon compounds, cyclic unsaturated hydrocarbon compounds, saturated heterocyclic compounds, unsaturated heterocyclic compounds, and silicone compounds, which are crosslinked chemically with such compounds. The polysilazane selected as the (A-1) component must contain at least one hydrogen atom directly bonded to a silicon atom in one molecule. Among them, perhydropolysilazane is more preferable from the viewpoint of the film properties after curing.

（式中Ｒ^２は水素原子、または炭素数１～６の脂肪族炭化水素基、炭素数６～１２の芳香族炭化水素基、炭素数１～６のアルコキシ基から選ばれる基であり、Ｒ^３は炭素数１～６の脂肪族炭化水素基、炭素数６～１２の芳香族炭化水素基、炭素数１～６のアルコキシ基から選ばれる基である） (A-2) The following formula (2)

(In the formula, ^R2 is a hydrogen atom or a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms, and ^R3 is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms.)

The polysilazane compound (A-2) is a polysilazane compound consisting of the repeating unit represented by the above formula (2). Examples include modified polysilazanes such as monomethylpolysilazane or dimethylpolysilazane, phenylpolysilazane, vinylpolysilazane, methoxypolysilazane, and ethoxypolysilazane; hydrocarbon compounds having reactive groups such as hydroxyl groups, vinyl groups, amino groups, and silyl groups that chemically react with polysilazane to form crosslinked structures; cyclic saturated hydrocarbon compounds, cyclic unsaturated hydrocarbon compounds, saturated heterocyclic compounds, unsaturated heterocyclic compounds, and silicone compounds that are crosslinked chemically; and the like. Among these, monomethylpolysilazane is preferred from the viewpoint of film properties and crack resistance after curing.

In the present invention, it is important that the (A-1) component for expressing gas barrier properties and the (A-2) component for expressing crack resistance are mixed in an appropriate ratio. Specifically, the mixing ratio of the (A-1) and (A-2) components must be in the range of 7/3 to 3/7 by mass. Outside this range, the properties of one of the polysilazanes will be strongly reflected, and the properties of the two types of polysilazanes will not be well balanced.

If the amount of (A-1) component is greater than this ratio, the coating film may crack during curing or the reflow process. Also, if there is a large amount of (A-2) component, the gas barrier performance of the coating film will be insufficient.

In addition, the weight average molecular weight of the (A-1) component that exhibits gas barrier properties must be in the range of 3,000 to 50,000, and is more preferably in the range of 5,000 to 10,000. If the weight average molecular weight is less than 3,000, the curing shrinkage becomes large, residual stress is likely to remain in the film, and cracks are likely to occur. In addition, there are many low molecules that volatilize during heat curing, which may cause the film quality to deteriorate and the gas barrier performance to decrease. On the other hand, if the weight average molecular weight is more than 50,000, it is difficult to obtain the stress relaxation effect of the (A-2) component, and cracks are likely to occur during reflow. The weight average molecular weight was measured using a GPC device by the following method.
[Measurement condition]
Developing solvent: tetrahydrofuran (THF)
Flow rate: 0.6 mL/min
Detector: UV detector Column: TSK Guardcolumn SuperH-L
TSKgel SuperMultipore HZ-M
(4.6mm I.D. x 15cm x 4)
(Both manufactured by Tosoh Corporation)
Column temperature: 40°C
Sample injection volume: 20 μL (THF solution with a concentration of 0.5% by weight)

It is also preferred that R ¹ is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms, and that R ² is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms.

(B) Organic Solvent There are no particular limitations on the organic solvent used in the present invention as long as it dissolves the polysilazane compound used. However, since the organic solvent is used for electronic materials, it is preferable to avoid the use of solvents that tend to contain water, high boiling point solvents, non-volatile solvents, etc.

Specific examples of organic solvents include alkane compounds such as n-hexane, n-octane, and n-nonane; alkene compounds such as 1-octene, 1-nonene, and 1-decene; cycloalkane compounds such as cyclohexane, methylcyclohexane, and dimethylcyclohexane; ester compounds such as n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, isoamyl acetate, and ethyl caproate; and ether compounds such as diethyl ether, dibutyl ether, and ethylene glycol diethyl ether. Among these, dibutyl ether and isoamyl acetate are particularly preferred from the viewpoints of the solubility of polysilazane and wettability to inorganic and organic materials.

The mixing ratio of the polysilazane compound to the organic solvent is in the range of 0.1/99.9 to 20/80 by mass, preferably 1/99 to 20/80, and more preferably 2.5/97.5 to 20/80. Within this range, the storage stability and coatability are good, and the thickness that can be applied at one time is also large, which is preferable.

[Other additives]
The coating agent for protecting electronic materials of the present invention may contain additives such as a curing catalyst and a filler in addition to the polysilazane compound and the organic solvent. For example, homogeneous or heterogeneous metal catalysts containing metal elements such as magnesium, aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, zinc, gallium, zirconium, niobium, palladium, and platinum, aliphatic amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, and tetramethylethylenediamine, aliphatic amino alcohols such as methylaminoethanol and dimethylaminoethanol, aromatic amines such as aniline, phenylethylamine, and toluidine, pyrrolidine, piperidine, piperazine, pyrrole, pyrazole, imidazole, pyridine, pyridazine, and pyrimidine pyrazine. reinforcing inorganic fillers such as fumed silica, fumed titanium dioxide, and fumed alumina; non-reinforcing inorganic fillers such as fused silica, alumina, zirconium oxide, calcium carbonate, calcium silicate, titanium dioxide, ferric oxide, and zinc oxide; adhesion aids such as organosiloxane oligomers containing at least two, and preferably two or three, functional groups selected from hydrosilyl groups, alkenyl groups, alkoxysilyl groups, and epoxy groups, organooxysilyl-modified isocyanurate compounds and hydrolysis condensates thereof; and silicone oils such as dimethyl silicone and phenyl silicone, which can be added in any ratio depending on the required properties.

Methods for applying the coating agent for protecting electronic materials of the present invention include, for example, roll coating methods using a chamber doctor coater, single roll kiss coater, reverse kiss coater, bar coater, reverse roll coater, forward rotation roll coater, blade coater, knife coater, etc., spin coating methods, dispensing methods, dipping methods, spraying methods, transfer methods, slit coating methods, etc.

There are no particular restrictions on the substrate to which the coating is applied, so long as it is used as an electronic material itself or a peripheral component thereof. Examples include silicone substrates, glass substrates, metal substrates, resin substrates, and resin films, and if necessary, the coating may be applied to substrates on which semiconductor films or circuits are provided in the process of forming semiconductor elements. The thickness of the coating varies depending on the difference in linear expansion coefficient with the substrate and the temperature to which it is exposed, but generally the cured thickness is 100 to 50,000 nm, and preferably 500 to 10,000 nm.

After forming a polysilazane resin coating film by applying the coating agent in this way, it is preferable to heat and dry the coating film in order to harden it. The purpose of this process is to completely remove the solvent contained in the coating film and to promote a hardening reaction that promotes the exchange reaction from polysilazane to polysiloxane bonds.

The heating and drying temperature is usually between room temperature (25°C) and 300°C, preferably between 70°C and 200°C. Preferred methods for the heating and drying process include heat treatment, steam heating treatment, and UV treatment. When curing perhydropolysilazane, methods such as excimer light treatment can be used, but if the polysilazane contains organic groups, the organic groups may be cleaved by the energy of the excimer light, increasing the hardness of the cured film. The content of organic groups has a large effect on crack resistance, so it is best to avoid curing with excimer light, as this can create a gap with the design value and cause defects such as cracks and peeling.

The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to the following examples. Note that in the following examples, parts indicate parts by weight.

[Example 1]
A polysilazane dibutyl ether solution was prepared by mixing 7 parts of perhydropolysilazane having a weight average molecular weight of 6,500, 3 parts of monomethylpolysilazane having a weight average molecular weight of 1,100, and 90 parts of dibutyl ether as a solvent. A 5 mm x 2 mm x 1.5 mmH size capacitor with the outermost layer treated with copper paste was dipped into the prepared solution, and dried at 100°C in air for 10 minutes to obtain a polysilazane coating film. Next, the capacitor was heated at 150°C in air for 48 hours to harden the polysilazane coating film and apply a glassy coating.

[Example 2]
5 parts of perhydropolysilazane with a weight average molecular weight of 6,500, 5 parts of monomethylpolysilazane with a weight average molecular weight of 1,100, and 90 parts of dibutyl ether as a solvent were mixed to prepare a dibutyl ether solution of polysilazane. A 5 mm x 2 mm x 1.5 mmH size capacitor with the outermost layer treated with copper paste was dipped into the prepared solution, and dried at 100°C in air for 10 minutes to obtain a polysilazane coating film. Next, the capacitor was heated at 150°C in air for 48 hours to harden the polysilazane coating film and apply a glassy coating.

[Example 3]
A polysilazane dibutyl ether solution was prepared by mixing 3 parts of perhydropolysilazane having a weight average molecular weight of 6,500, 7 parts of monomethylpolysilazane having a weight average molecular weight of 1,100, and 90 parts of dibutyl ether as a solvent. A 5 mm x 2 mm x 1.5 mmH size capacitor with the outermost layer treated with copper paste was dipped into the prepared solution, and dried at 100°C in air for 10 minutes to obtain a polysilazane coating film. Next, the capacitor was heated at 150°C in air for 48 hours to harden the polysilazane coating film and apply a glassy coating.

[Comparative Example 1]
10 parts of perhydropolysilazane with a weight average molecular weight of 6,500 and 90 parts of dibutyl ether as a solvent were mixed to prepare a dibutyl ether solution of polysilazane. A capacitor with a size of 5 mm x 2 mm x 1.5 mmH and whose outermost layer was treated with copper paste was dipped into the prepared solution, and dried at 100°C in air for 10 minutes to obtain a polysilazane coating film. Next, the capacitor was heated at 150°C in air for 48 hours to harden the polysilazane coating film and provide a glassy coating.

[Comparative Example 2]
A polysilazane dibutyl ether solution was prepared by mixing 2 parts of perhydropolysilazane with a weight average molecular weight of 6,500 and 98 parts of dibutyl ether as a solvent. A 5 mm x 2 mm x 1.5 mmH capacitor with the outermost layer treated with copper paste was dipped into the prepared solution and dried at 100°C in air for 10 minutes to obtain a polysilazane coating film. Next, the capacitor was heated at 150°C in air for 48 hours to harden the polysilazane coating film and provide a glassy coating.

[Comparative Example 3]
10 parts of monomethylpolysilazane with a weight average molecular weight of 1,100 and 90 parts of dibutyl ether as a solvent were mixed to prepare a dibutyl ether solution of polysilazane. A capacitor with a size of 5 mm x 2 mm x 1.5 mmH and whose outermost layer was treated with copper paste was dipped into the prepared solution, and dried at 100°C in air for 10 minutes to obtain a polysilazane coating film. Next, the capacitor was heated at 150°C in air for 48 hours to harden the polysilazane coating film and apply a glassy coating.

[Comparative Example 4]
9 parts of perhydropolysilazane with a weight average molecular weight of 6,500, 1 part of monomethylpolysilazane with a weight average molecular weight of 1,100, and 90 parts of dibutyl ether as a solvent were mixed to prepare a dibutyl ether solution of polysilazane. A 5 mm x 2 mm x 1.5 mmH size capacitor with the outermost layer treated with copper paste was dipped into the prepared solution, and dried at 100°C in air for 10 minutes to obtain a polysilazane coating film. Next, the capacitor was heated at 150°C in air for 48 hours to harden the polysilazane coating film and apply a glassy coating.

[Comparative Example 5]
A polysilazane dibutyl ether solution was prepared by mixing 1 part of perhydropolysilazane having a weight average molecular weight of 6,500, 9 parts of monomethylpolysilazane having a weight average molecular weight of 1,100, and 90 parts of dibutyl ether as a solvent. A 5 mm x 2 mm x 1.5 mmH size capacitor with the outermost layer treated with copper paste was dipped into the prepared solution, and dried at 100°C in air for 10 minutes to obtain a polysilazane coating film. Next, the capacitor was heated at 150°C in air for 48 hours to harden the polysilazane coating film and apply a glassy coating.

[Comparative Example 6]
5 parts of perhydropolysilazane with a weight average molecular weight of 1,800, 5 parts of monomethylpolysilazane with a weight average molecular weight of 1,100, and 90 parts of dibutyl ether as a solvent were mixed to prepare a dibutyl ether solution of polysilazane. A 5 mm x 2 mm x 1.5 mmH size capacitor with the outermost layer treated with copper paste was dipped into the prepared solution, and dried at 100°C in air for 10 minutes to obtain a polysilazane coating film. Next, the capacitor was heated at 150°C in air for 48 hours to harden the polysilazane coating film and apply a glassy coating.

[Comparative Example 7]
5 parts of perhydropolysilazane with a weight average molecular weight of 54,000, 5 parts of monomethylpolysilazane with a weight average molecular weight of 1,100, and 90 parts of dibutyl ether as a solvent were mixed to prepare a dibutyl ether solution of polysilazane. A 5 mm x 2 mm x 1.5 mmH size capacitor with the outermost layer treated with copper paste was dipped into the prepared solution, and dried at 100°C in air for 10 minutes to obtain a polysilazane coating film. Next, the capacitor was heated at 150°C in air for 48 hours to harden the polysilazane coating film and apply a glassy coating.

[Reference Example 1]
A capacitor having a size of 5 mm×2 mm×1.5 mmH and an outermost layer treated with copper paste was prepared.

[Reflow test]
A reflow test was carried out on the capacitor samples produced in the Examples, Comparative Examples and Reference Examples using a reflow device manufactured by Tamura Corporation. The reflow conditions were that the samples were passed once through a 2 m long furnace heated stepwise to 150°C, 200°C, 220°C, 260°C and 265°C on a conveyor at a speed of 0.35 m/min. The appearance was then confirmed.

[Sulfuration test]
The sulfuration test was carried out on the capacitor samples produced in the examples, comparative examples, and reference examples after the above-mentioned reflow test. The test method was to place each sample in a sealed container together with sulfur powder, heat it in a convection dryer at 80°C for 100 hours, and then observe the change in the copper paste portion under a microscope.

The results of the Examples, Comparative Examples, and Reference Examples are summarized in Table 1. In addition, when there was no particular problem in appearance, a rating of ◯ was given, and otherwise a rating of defective mode was given.

In the examples and comparative examples, all samples except Comparative Examples 1 and 6 did not suffer from defects in appearance such as cracks or peeling after curing. The reason why cracks occurred after curing in Comparative Examples 1 and 6 is thought to be because the coating film had poor crack resistance and could not withstand the stress caused by cure shrinkage. In Comparative Examples 1, 2, 4, 6, and 7, cracks and peeling were confirmed in the coating film after the reflow test. This is presumably due to the difference in linear expansion between the capacitor and the coating film. On the other hand, in Examples 1 to 3 and Comparative Examples 3 and 5, no defects occurred in the coating film even after reflow. When a sulfurization test was performed after the reflow test, blackening due to sulfurization of the copper paste part was confirmed in all samples of the comparative examples and reference examples. For samples in which cracks and peeling occurred, this is a natural result because the coating does not function as a gas barrier film. For Comparative Examples 3 and 5, no defects occurred in the coating film, but it is suggested that the gas barrier properties of the coating film itself were insufficient. From these facts, it can be said that the coating film of the present invention has reflow resistance essential for electronic material parts and exhibits high sulfurization resistance.

The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included within the technical scope of the present invention.

Claims (2)

(A) a mixture of two types of polysilazane compounds having different structures, consisting of the following (A-1) and (A-2), and (A-1) a polysilazane compound represented by the following formula (1):

(wherein R ¹ is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms ).
and a weight average molecular weight of the polysilazane compound having a repeating unit represented by the formula:
(A-2) The following formula (2)

(In the formula, ^R2 is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms, and R3 is a group selected from an aliphatic ^hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms.)
A polysilazane compound having a repeating unit represented by the formula:
(B) A coating agent for protecting electronic materials, which contains an organic solvent, and is characterized in that a mixing ratio of the component (A-1) to the component (A-2) satisfies a range of 7/3 to 3/7 in terms of mass ratio. The coating agent for protecting electronic materials according to claim 1, characterized in that the mixing ratio of the (A) component to the (B) component is 0.1/99.9 to 20/80.