JP7085857B2 - Resin composition, protective film for chip resistors, and chip resistors - Google Patents

Description

The present invention relates to a resin composition, a protective film for a chip resistor, and a chip resistor, and in particular, a resin composition having excellent heat resistance after curing, a protective film for a chip resistor having excellent heat resistance, and a chip having excellent heat resistance. The present invention relates to a chip resistor including a protective film for the resistor.

In recent years, there has been a demand for higher heat resistance of in-vehicle electronic components. In-vehicle electronic components are being considered for use at a position closer to the engine than before. Until now, the long-term evaluation standard for heat-resistant temperature was 150 ° C, but now heat resistance at 200 ° C. Is becoming more and more sought after.

This heat resistance is required to have good adhesion after a long period of time, for example, after 1000 hours. The conventional resin composition has secured sufficient adhesion after a long period of time at 150 ° C., but has a problem that the adhesion is lowered after being held for a long time at 200 ° C.

As a heat-resistant paint that does not deteriorate at high temperatures and has good adhesion to metals and the like, a heat-resistant paint containing a predetermined polyimide resin and a tetrafunctional epoxy resin having a naphthalene skeleton has been reported (Patent Document 1).

However, since the heat-resistant paint containing a predetermined polyimide resin and a tetrafunctional epoxy resin having a naphthalene skeleton uses a polyimide resin, a large amount of solvent is required to form a varnish. Therefore, this heat-resistant paint has problems that it is difficult to obtain a thick film, and that a solvent capable of dissolving polyimide dissolves an emulsion for screen printing.

Japanese Unexamined Patent Publication No. 2012-131856

An object of the present invention is to solve the above problems, that is, to provide a resin composition capable of forming a cured film having sufficient adhesion after being held at a high temperature (for example, 200 ° C.). ..

The present invention relates to a resin composition, a protective film for a chip resistor, and a chip resistor that solve the above problems by having the following configurations.
[1] Contains an inorganic filler containing (A) a naphthylene ether type epoxy resin, (B) an amine-based curing agent, and (C) at least (c1) talc.
A resin composition characterized in that the content of the component (c1) is 15 to 40 parts by mass with respect to a total of 100 parts by mass of the component (A), the component (B) and the component (C).
[2] The resin composition according to the above [1], wherein the component (C) further contains (c2) a silica filler.
[3] A coating agent for a protective film for a chip resistor using the resin composition according to the above [1] or [2].
[4] Contains an inorganic filler containing (A) a naphthylene ether type epoxy resin, (B) an amine-based curing agent, and (C) at least (c1) talc.
A chip resistor having a cured product of a resin composition in which the content of the component (c1) is 15 to 40 parts by mass with respect to a total of 100 parts by mass of the component (A), the component (B) and the component (C). Protective film.
[5] A chip resistor including the protective film according to the above [4].

According to the present invention [1], it is possible to provide a resin composition capable of forming a cured film having sufficient adhesion after being held at a high temperature (for example, 200 ° C.).

According to the present invention [4], it is possible to provide a protective film for a chip resistor, which is a cured film of a resin composition having sufficient adhesion after being held at a high temperature (for example, 200 ° C.).

According to the present invention [5], it is possible to provide a highly reliable chip resistor including a protective film of the chip resistor having sufficient adhesion after being held at a high temperature (for example, 200 ° C.).

[Resin composition]
The resin composition of the present invention (hereinafter referred to as a resin composition) comprises an inorganic filler containing (A) a naphthylene ether type epoxy resin, (B) an amine-based curing agent, and (C) at least (c1) talc. Including
The content of the component (c1) is 15 to 40 parts by mass with respect to 100 parts by mass in total of the component (A), the component (B) and the component (C).

The naphthylene ether type epoxy resin as the component (A) imparts adhesiveness to the resin composition. Most of the resins having excellent heat resistance generally have a high glass transition point (Tg), and the resin having a high glass transition point has a rigid molecular structure due to an aromatic ring or the like and an increase in the crosslink density of the resin. Often achieved. However, when the crosslink density of the resin is increased, the internal stress increases and the adhesion to the adherend tends to decrease. On the other hand, it is considered that the cured product using the component (A) contains a large amount of bifunctional molecules, and the crosslink density is less likely to increase as compared with the conventional highly heat-resistant resin, and therefore the adhesion is less likely to decrease. .. Further, it is considered that the naphthalene ether type epoxy resin has a naphthalene structure connected by an ether group instead of a methylene group, and is superior in chemical heat resistance to the conventional high heat resistant resin. The component (A) is not particularly limited, but the general formula (1):

The naphthylene ether type epoxy resin represented by the above, wherein in the formula, R ¹ and R ² are independently hydrogen atoms, benzyl groups, alkyl groups, or the general formula (2) :.

In the formula, Ar is independently a phenylene group or a naphthylene group, m is an integer of 1 or 2, and n is an integer of 1 to 20. , Can be mentioned.

The epoxy equivalent of the (A) naphthylene ether type epoxy resin is preferably 180 to 1000, more preferably 190 to 900, further preferably 200 to 800, still more preferably 210 to 700, and particularly preferably 230 to 500. .. As the epoxy equivalent increases, Tg generally tends to decrease, but the total number of epoxy groups, which are considered to have weak chemical heat resistance, decreases, so that the chemical heat resistance of the resin composition as a whole improves. ..

As a specific example of the component (A), for example, the naphthylene ether type epoxy resin represented by the formula (6) or the formula (7) disclosed in "Network Polymer" Vol30, No4, P192 (2009) can be used. Can be mentioned. As commercially available products of the component (A), DIC's naphthylene ether type epoxy resin (product name: Epicron HP-6000 (epoxy equivalent 240 to 270)), (product name: EXA-7310 (epoxy equivalent 247), EXA- 7311 (epoxy equivalent 277), EXA-7311L (epoxy equivalent 262), EXA7311-G3 (epoxy equivalent 250)) and the like can be mentioned. The component (A) may be used alone or in combination of two or more.

The amine-based curing agent as the component (B) imparts curability to the resin composition. The component (B) is not particularly limited, and examples of the amine-based curing agent include aromatic diamine-based curing agents, dicyandiamide, and imidazole compounds. The aromatic diamine-based curing agent is a compound having two amino groups in the molecule and having an aromatic ring structure. By selecting an aromatic diamine-based curing agent, heat resistance (adhesion retention) can be imparted to the cured product as compared with other amine-based curing agents. Examples of the aromatic diamine-based curing agent include m-phenylenediamine, p-phenylenediamine, o-xylenediamine, 4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 4,4. '-Diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 1,5-diaminonaphthalene, 4,4'-(p-phenylenediisopropi) Liden) Dianeline and the like can be mentioned. From the viewpoint of heat resistance, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, and 3,3'-diethyl-4,4'-diaminodiphenylmethane are preferable, and liquid is particularly preferable from the viewpoint of uniform dispersion. 3,3'-diethyl-4,4'-diaminodiphenylmethane is preferable. The dicyandiamide can provide a cured product having both long-term heat resistance and a high glass transition point (Tg). Examples of the imidazole compound include 2-ethyl-4-methylimidazole, 2-phenyl-4-hydroxymethyl-5-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and the like, and particularly from the viewpoint of promoting curing. , 2-Ethyl-4-methylimidazole is preferred. In the case of a phenol curing agent (resole type), a cured product having a high Tg can be obtained, but the cured product is harder and more brittle than the cured product cured with dicyandiamide, so that the long-term heat resistance is deteriorated. It ends up. In addition, the acid anhydride-based curing system is difficult to use in screen printing because its characteristics change due to moisture absorption.

The component (C) imparts low thermal expansion to the resin composition. As a result, dimensional changes due to temperature changes are suppressed, and high heat resistance (adhesion retention) can be obtained. The component (C) contains at least (c1) talc from the viewpoint of long-term heat resistance. The component (c1) significantly improves heat resistance (adhesion retention). The shape of the talc powder (c1) is preferable because it has a plate-like shape and a flat shape, and can suppress expansion and contraction of the resin in the plane direction after curing. The average particle size (length in the plane direction) of the talc powder is not particularly limited, but 1 to 10 μm is suitable for the low thermal expansion of the resin composition and the dispersibility of the component (c1) in the resin composition. Preferred from the point of view. If it is less than 1 μm, the effect of suppressing the expansion and contraction of the resin in the surface direction may be reduced. If it exceeds 10 μm, it may be difficult to uniformly disperse the component (c1) in the coating film formed from the resin composition. Here, the average particle size of the component (c1) refers to a volume-based median diameter measured by a laser diffraction method. Examples of commercially available products include talc manufactured by Matsumura Sangyo Co., Ltd. (product name: High Filler # 5000PJ). The component (c1) may be used alone or in combination of two or more. It should be noted that montmorillonite, which is known as a silicate mineral like talc, has a high concentration of ionic impurities and is imparted with rocking denaturation, so it is difficult to add a sufficient amount to function as a filler; kaolinite is used. , High concentration of ionic minerals, high water absorption, poor moisture resistance; mica is hard and has poor printability.

It is preferable that the component (C) further contains (c2) a silica filler in the resin composition from the viewpoint of scratch resistance. The addition of (c2) is particularly effective when the cured resin composition is barrel-plated. Examples of the component (c2) include colloidal silica, hydrophobic silica, fine silica, nanosilica and the like. The average particle size of the component (c2) (if not granular, the average maximum diameter thereof) is not particularly limited, but the dispersibility of the component (c2) in the resin composition is 0.1 to 10 μm. It is also preferable from the viewpoint of reducing the melt viscosity of the resin composition. If it is less than 0.1 μm, the viscosity of the resin composition may increase and workability such as printability may deteriorate. If it exceeds 10 μm, it may be difficult to uniformly disperse the component (c2) in the resin composition. Here, the average particle size of the component (c2) refers to a volume-based median diameter measured by a laser diffraction method. Commercially available products include Admatex silica (product name: SO-E2, average diameter: 0.5 μm), Admatex silica (product name: SE-1050, average diameter: 0.3 μm), and Tatsumori. Silica (product name: MP-8FS, average diameter: 0.7 μm), DENKA silica (product name: FB-5D, average diameter: 5 μm), Fuso Chemical Industry (product name: SP03B, average diameter: 300 nm) ) Etc. can be mentioned. The component (c2) may be used alone or in combination of two or more.

From the viewpoint of maintaining the heat-resistant physical properties of the cured product, the lower limit of the content of the component (A) is preferably 40 parts by mass or more, and more preferably 45 parts by mass or more with respect to 100 parts by mass of the non-volatile content in the resin composition. On the other hand, the upper limit of the content of the component (A) is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, and more preferably 60 parts by mass with respect to 100 parts by mass of the non-volatile content in the resin composition from the viewpoint of thermal expansion. It is more preferably parts by mass or less.

The content of the component (B) is the total content of the component (A) when the component (B) is an aromatic diamine-based curing agent (when other epoxy compounds are contained, the total content including them). The equivalent ratio to the epoxy functional value of) is preferably in the range of 0.8 to 1.2. When the component (B) is a dicyandiamide and / or an imidazole compound, 0. It is preferably in the range of 1 to 20 parts by mass, and more preferably in the range of 1 to 10 parts by mass.

The content of the component (c1) is 15 to 40 parts by mass with respect to 100 parts by mass in total of (A), (B) and (C). If the component of (c1) is less than 15 parts by mass, the function of suppressing the expansion and contraction of the resin in the plane direction is insufficient, so that the resin is easily peeled off from the adherend or the cured product is easily cracked. On the other hand, if the component (c1) exceeds 40 parts by mass, the resin component serving as a binder is insufficient, and there is a concern that the deterioration of the cured product due to heat will be accelerated.

From the viewpoint of adhesion, the component (c2) is preferably in a range not exceeding 2.0 with respect to (c1) 1.0 in terms of mass ratio.

The total amount of the component (C) is preferably 50 parts by mass or less, and more preferably 43 parts by mass or less, based on 100 parts by mass of the total of (A), (B) and (C). When the total amount of the component (C) exceeds 50 parts by mass, the adhesion retention tends to be inferior. Even in this case, (c1) is 40 parts by mass or less.

The resin composition may contain a coupling agent such as a silane coupling agent, a tackifier, an antifoaming agent, a flow conditioner, a film forming aid, a dispersion aid, etc., as long as the effects of the present invention are not impaired. Additives can be included. It can also contain colored pigments.

The resin composition can be produced by dissolving or dispersing a raw material containing the components (A) to (C) in an organic solvent. The device for dissolving or dispersing these raw materials is not particularly limited, but a Raikai machine equipped with a stirring and heating device, a three-roll mill, a ball mill, a planetary mixer, a bead mill and the like can be used. .. Further, these devices may be used in combination as appropriate.

Examples of the organic solvent include butyl carbitol, butyl carbitol acetate; aromatic solvents such as toluene and xylene; and ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone. The organic solvent is preferable because the resin composition can be adjusted to a viscosity suitable for coating in screen printing or the like, and a high boiling point solvent having a boiling point of 150 ° C. or higher is less likely to volatilize from the resin composition during printing. Preferred are carbitol (boiling point: 200 ° C.), butyl carbitol (boiling point: 230 ° C.), and butyl carbitol acetate (boiling point: 247 ° C.). The organic solvent may be used alone or in combination of two or more. The amount of the organic solvent used is not particularly limited, but it is preferably used so that the solid content is 20 to 50% by mass. From the viewpoint of workability, the resin composition preferably has a viscosity in the range of 20 to 180 Pa · s. The viscosity is a value measured at a rotation speed of 50 rpm and 25 ° C. using an HB type viscometer.

The resin composition of the present invention can form a cured film having sufficient adhesion after being held at a high temperature (for example, 200 ° C.).

[Coating agent for protective film of chip resistors]
The above-mentioned resin composition is used as the coating agent for the protective film of the chip resistor of the present invention.

[Protective film for chip resistors]
The protective film of the chip resistor of the present invention is a cured product of the above-mentioned resin composition. That is, it contains (A) a naphthylene ether type epoxy resin, (B) an amine-based curing agent, and (C) an inorganic filler containing at least (c1) talc.
It has a cured product of a resin composition having a content of (c1) of 15 to 40 parts by mass with respect to a total of 100 parts by mass of (A), (B) and (C).

The protective film of the chip resistor is obtained by applying the resin composition to a desired portion of the chip resistor and then heat-curing it.

The method of applying the resin composition to the chip resistor is not particularly limited, and examples thereof include screen printing, dispensing, and dipping. Here, the thickness of the protective film of the chip resistor after thermosetting is preferably 10 to 50 μm from the viewpoint of ensuring insulation, protection from external force, and reduction of internal stress.

The thermosetting conditions can be appropriately set according to the type and amount of the organic solvent used in the resin composition, the thickness of the coating, and the like, and are, for example, about 10 to 120 minutes at 150 to 250 ° C. be able to.

As described above, the protective film of the chip resistor can be obtained. This protective film has sufficient adhesion after being held at a high temperature (for example, 200 ° C.).

[Chip resistor]
The chip resistor of the present invention includes the above-mentioned protective film. This chip resistor is highly reliable because it contains a protective film for the chip resistor having sufficient adhesion after being held at a high temperature (for example, 200 ° C.).

The present invention will be described with reference to Examples, but the present invention is not limited thereto. In the following examples, parts and% indicate parts by mass and% by mass unless otherwise specified.

As the component naphthylene ether type epoxy resin, naphthylene ether type epoxy resin manufactured by DIC Corporation (product name: Epicron HP-6000) is used.
The naphthalene-type epoxy resin of the component (A') is a naphthalene-type epoxy resin manufactured by DIC Co., Ltd. (product name: Epicron HP -4710), and the biphenyl-type epoxy resin is a biphenyl-type epoxy resin manufactured by Nippon Kayaku Co., Ltd. (product name). : NC-3000), and for the cresol novolac type epoxy resin, cresol novolac type epoxy resin manufactured by DIC Co., Ltd. (product name: Epicron N-665 EXP).
For the amine-based curing agent of the component (B),
(B1) 3,3'-diethyl-4,4'-diaminodiphenylmethane (amine-based curing agent manufactured by Nippon Kayaku Co., Ltd., product name: Kayahard AA),
(B2) For dicyandiamide, dicyandiamide (product name: CG1400) manufactured by Evonik Japan Co., Ltd. is used.
(B3) For 2-ethyl-4-methylimidazole, use imidazole (product name: 2E4MZ) manufactured by Shikoku Chemicals Corporation.
As the phenol curing agent (resole) of the component (B'), a resole-type phenol-based curing agent (product name: Nicanol PR-1440M) manufactured by Mitsubishi Gas Chemical Company, Inc. was used.
For the talc of the component (c1), talc powder manufactured by Matsumura Sangyo Co., Ltd. (product name: high filler # 5000PJ, average particle size: 4 μm) is used.
Silica powder (product name: Admafine SE-1050, average particle size: 0.3 μm) manufactured by Admatex Co., Ltd. was used as the silica component (c2).
As the coupling agent, a silane coupling agent (product name: KBM-403) manufactured by Shin-Etsu Chemical Co., Ltd. was used.

[Examples 1 to 7, Comparative Examples 1 to 10]
After the component (A) and the component (A') were solubilized with butyl carbitol acetate, the components (A) to (C) and the like were mixed at the ratios shown in Tables 1 and 2 using a three-roll mill.

[Evaluation of storage stability]
The stability of the dissolved state of the solution in which the component (A) and the component (A') were dissolved with butyl carbitol acetate (BCA) was visually confirmed. The presence or absence of reprecipitation of the component (A) and the component (A') was determined according to the following criteria.
◯: No reprecipitation occurred even after 1 week or more.
Δ: Reprecipitation occurred within 1 day or more and less than 1 week.
X: Reprecipitation took less than 1 day.
The evaluation was completed when the solubility became x.

[Evaluation of heat resistance]
The heat resistance of the cured resin composition was evaluated. The resin composition was screen-printed on a slide glass using a printing mask with a 1.5 mm □ pattern, heated in a batch furnace at 200 ° C. for 30 minutes, and cured to be a test piece, and the test piece was 200. After allowing the test piece to stand in a batch furnace kept at ° C for 1000 hours, the test piece was naturally cooled to room temperature, and then a tape peeling test of a cured film on a slide glass was performed using cellophane tape.
The number of cured films was 50, and the number of peeled films was visually determined according to the following criteria.
⊚: No peeling occurred.
◯: The number of peelings was 10 or less.
Δ: The number of peelings was 11 to 49.
X: All 50 pieces were peeled off.

As can be seen from Tables 1 and 2, Examples 1 to 7 had good storage stability and heat resistance. In particular, although not shown in Table 1, the heat resistance of Examples 1 to 3 and 5 was remarkably good even after the lapse of 5000 hours. In Example 4, since the component (c2) was large and the effect of containing the component (c1) was small, the heat resistance was slightly inferior to that of the other examples. Although not shown in Table 1, Examples 1 to 7 had very good storage stability, and no reprecipitation was observed even after 6 months. On the other hand, Comparative Example 1 having too few components (c1) and Comparative Example 2 having too many components (c1) had poor heat resistance. Comparative Example 3 in which a naphthalene-type epoxy resin was used instead of the component (A) and Comparative Example 4 in which a biphenyl-type epoxy resin was used instead of the component (A) had poor storage stability. Comparative Example 5 in which a cresol novolac type epoxy resin was used instead of the component (A), Comparative Example 6 in which a phenol type curing agent was used instead of the component (B), and Comparative Examples 7 to 10 containing no component (c1) , The heat resistance was bad.

As described above, the resin composition of the present invention has sufficient adhesion and good storage stability after being held at a high temperature (for example, 200 ° C.).

Claims (5)

It contains (A) a naphthylene ether type epoxy resin, (B) an amine-based curing agent, and (C) an inorganic filler containing at least (c1) talc.
The content of the component (c1) is 15 to 40 parts by mass with respect to the total of 100 parts by mass of the component (A), the component (B) and the component (C), and the total amount of the component (C) is (A). A resin composition, which is 50 parts by mass or less with respect to 100 parts by mass in total of (B) and (C). The resin composition according to claim 1, wherein the component (C) further contains (c2) a silica filler. A coating agent for a protective film of a chip resistor using the resin composition according to claim 1 or 2. It contains (A) a naphthylene ether type epoxy resin, (B) an amine-based curing agent, and (C) an inorganic filler containing at least (c1) talc.
The content of the component (c1) is 15 to 40 parts by mass with respect to the total of 100 parts by mass of the component (A), the component (B) and the component (C), and the total amount of the component (C) is (A). ), (B) and (C), a protective film for a chip resistor having a cured product of a resin composition of 50 parts by mass or less with respect to 100 parts by mass in total . A chip resistor comprising the protective film according to claim 4.