JP7107802B2 - resin composition - Google Patents

Description

The present invention relates to resin compositions. More particularly, it relates to a resin composition suitable as a sealing material for electronic parts such as semiconductors.

2. Description of the Related Art Conventionally, in the field of encapsulation technology for semiconductor elements such as transistors and ICs, resin encapsulation has been the mainstream from the standpoint of productivity, cost, and the like. A resin composition for encapsulation containing an epoxy resin, a phenolic resin curing agent, a curing accelerator, and an inorganic filler as essential components is used as the encapsulation resin, and lead frames and semiconductor elements are resin-encapsulated as semiconductor devices. It is
On the other hand, the required performance of semiconductor devices is becoming more and more sophisticated, and the required power density is in an area that is difficult for conventional Si devices to reach.
Under these circumstances, further increase in power density is expected, and SiC power devices can be cited as devices that have been developed in recent years. reaches 250°C.
Therefore, there is a strong demand for the development of a heat-resistant sealing material that can withstand such temperatures and maintain its physical properties for 1000 hours or longer.
However, such materials have a molding temperature or a curing temperature of 200° C. or higher, and must be handled at extremely high temperatures. It is necessary.

Conventionally, amines, imidazoles and the like have been widely used as curing accelerators for epoxy and cyanate ester resins. Patent Documents 1 and 2 describe high heat-resistant resins using cyanate ester resin compositions.

However, the cyanate ester resin described in Patent Document 1 requires heat curing at a high temperature for a long period of time to form an oxazole ring through a reaction between an epoxy group and a cyanato group, and has a problem of poor productivity. In addition, the composition described in Patent Document 2 contains transition metal ions such as Co and corrodes metal members made of aluminum or the like, and thus has insufficient moisture resistance. There is a problem that deterioration of characteristics occurs.

Japanese Unexamined Patent Application Publication No. 2016-216708 JP 2015-86337 A

An object of the present invention is to provide a resin composition which is excellent in curability even at 200° C. or lower and which gives a cured product with excellent heat resistance.

［一般式（１）中、Ｒ¹、Ｒ²およびＲ³は、それぞれ独立にシクロヘキシル基、フェニル
基、炭素数１～２０のアルキル基又は水素原子であり、Ｒ¹、Ｒ²又はＲ³の少なくとも１つは水素原子である。］

［一般式（２）中、ｍは２～６の整数であり、それぞれのメチレン基の水素原子は有機基で置換されていてよい。］ The present inventors arrived at the present invention as a result of intensive studies in order to solve the above problems.
That is, the present invention contains an epoxy resin (A), a curing agent (B) and a curing accelerator (C), and the curing accelerator (C) is a compound represented by the general formula (1) , and a base represented by general formula (2).

[In the general formula ( ¹ ), R ¹ , R ² and R ³ are ^each independently a cyclohexyl group, a phenyl group, an alkyl group having ¹ to 20 carbon atoms, or a hydrogen atom; At least one is a hydrogen atom. ]

[In general formula (2), m is an integer of 2 to 6, and a hydrogen atom of each methylene group may be substituted with an organic group. ]

The resin composition (S) of the present invention has the following effects.
(1) Excellent curability even at a lower curing temperature (for example, 180° C.) than before.
(2) Since the cured product has excellent heat resistance, the glass transition temperature is high, the weight loss temperature is high, and cracks do not occur even at high temperatures.
(4) Since the coefficient of linear expansion is low, the cured product is excellent as a resin sealing material.
(5) It is easy to handle due to little increase in viscosity over time.

<Epoxy resin (A)>
Examples of the epoxy resin (A) in the present invention include phenol novolak type epoxy resin, naphthol novolak type epoxy resin, cresol novolak type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, naphthylene ether type epoxy resin, glycidyl ester type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, anthracene type epoxy resin , glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, epoxy resin having a butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, spiro ring-containing epoxy resin, cyclohexanedimethanol type epoxy resin, trimethylol type epoxy resin , tetraphenylethane type epoxy resin, and the like. The epoxy resin (A) may be used alone or in combination of two or more.

Of the epoxy resins (A), preferred from the viewpoint of resin physical properties are phenol novolak type epoxy resins, cresol novolak type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, alicyclic epoxy resins, and naphthalene type epoxy resins. epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthylene ether-type epoxy resins, glycidyl ester-type epoxy resins, anthracene-type epoxy resins, and epoxy resins having a butadiene structure, more preferably phenol novolak-type epoxy resins, Bisphenol A type epoxy resins, alicyclic epoxy resins and naphthalene type epoxy resins are preferred, and phenol novolac type epoxy resins are particularly preferred.

The epoxy equivalent (unit: g/eq) of the epoxy resin (A) is preferably 140-600, more preferably 170-300, from the viewpoint of resin physical properties.

<Curing agent (B)>
The curing agent (B) in the present invention includes, for example, a bisphenol type cyanate ester (B1), a triazine skeleton-containing phenol curing agent (B2), a novolac type cyanate ester curing agent (B3), a dicyclopentadiene type cyanate ester curing agent ( B4).

Examples of the bisphenol-type cyanate ester curing agent (B1) include bisphenol A-type, bisphenol F-type, bisphenol S-type, and bisphenol E-type polycyanate esters (preferably dicyanate esters).

Examples of the triazine skeleton-containing phenol curing agent (B2) include commercially available "LA3018", "LA7054" and "LA1356" [all manufactured by DIC Corporation].

The novolak-type cyanate ester curing agent (B3) has a novolac structure and has an average of at least two cyanato groups (—OCN) in one molecule (preferably 2 to 6). One example is "PT30" [manufactured by Lonza Japan Co., Ltd.].

Examples of the dicyclopentadiene-type cyanate ester curing agent (B4) include polyfunctional cyanate resins derived from dicyclopentadiene structure-containing phenol resins. 7000” [both manufactured by Lonza Japan Co., Ltd.].

Among the curing agents (B), from the viewpoint of resin physical properties and heat resistance, preferred are (B1), (B3) and (B4), and more preferred is (B1).

［一般式（１）中、Ｒ¹、Ｒ²およびＲ³は、それぞれ独立にシクロヘキシル基、フェニル
基、炭素数１～２０のアルキル基又は水素原子であり、Ｒ¹、Ｒ²又はＲ³の少なくとも１つは水素原子である。］

［一般式（２）中、ｍは２～６の整数であり、それぞれのメチレン基の水素原子は有機基で置換されていてよい。］ <Curing accelerator (C)>
The curing accelerator (C) in the present invention is a salt composed of a compound represented by general formula (1) and a base represented by general formula (2).

[In the general formula ( ¹ ), R ¹ , R ² and R ³ are ^each independently a cyclohexyl group, a phenyl group, an alkyl group having ¹ to 20 carbon atoms, or a hydrogen atom; At least one is a hydrogen atom. ]

[In general formula (2), m is an integer of 2 to 6, and a hydrogen atom of each methylene group may be substituted with an organic group. ]

The compound represented by the general formula (1) is an organic phosphonic acid when R ³ is a cyclohexyl group, phenyl group or an alkyl group having 1 to 20 carbon atoms and R ¹ and R ² are hydrogen atoms.
A compound in which one of R ¹ and R ² in the general formula (1) is a cyclohexyl group, a phenyl group or an alkyl group having 1 to 20 carbon atoms and the other is a hydrogen atom is a phosphonic acid monoester.
When R ¹ and R ² in general formula (1) are each independently a cyclohexyl group, a phenyl group, or an alkyl group having 1 to 20 carbon atoms, and R ³ is a hydrogen atom, the compound is a phosphonic acid diester is.
From the viewpoint of curability, at least one of R ¹ , R ² and R ³ is a hydrogen atom, more preferably R ¹ and R ² are hydrogen atoms.

Among the above compounds, from the viewpoint of curability, phenylphosphonic acid, alkylphosphonic acid and dialkyl phosphonate are preferred, and phenylphosphonic acid, hexylphosphonic acid and diethyl phosphonate are more preferred.

The base represented by the general formula (2) is 1,5-diazabicyclo[4,3,0]-nonene-5 (DBN), 1,5-diazabicyclo[4,4,0]-decene-5,1 ,8-diazabicyclo[5,4,0]-undecene-7 (DBU; “DBU” is a registered trademark of San-Apro Co., Ltd.), 5-hydroxypropyl-1,8-diazabicyclo[5,4,0] -undecene-7 and 5-dibutylamino-1,8-diazabicyclo[5,4,0]-undecene-7. Of these, DBN and DBU are preferred.

The curing accelerator (C) is a salt composed of the phosphonic acid or its ester compound and the base.
Any combination of the above-exemplified phosphonic acid or its ester compound and the above-exemplified base may be used, but specific combinations include phenylsulfonic acid, hexylsulfonic acid, salts of diethyl phosphonate and DBU, and Salts of phenylsulfonic acid, hexylsulfonic acid, diethyl phosphonate and DBN are preferred.

The salt neutralization rate (%) is calculated by the following formula (1).

Neutralization rate (%) = (α) × 100/(β) (1)

(α): valence of phosphonic acid or its ester compound × number of moles, provided that the above valence is monovalent when there is one hydrogen atom among R ¹ , R ² and R ³ , and two hydrogen atoms. is bivalent, and when there are three hydrogen atoms, it is trivalent.
(β): Number of moles of base

The neutralization rate (%) is preferably 50 to 100%, more preferably 80 to 100%, from the viewpoint of curability and physical properties of the resin.

The curing accelerator (C) can be obtained, for example, by mixing the above phosphonic acid or its ester compound and the above base in a solvent, if necessary, as described in Examples below.
A salt composed of the phosphonic acid and the base represented by the general formula (2) can be obtained by reacting the dialkyl phosphonate with the base represented by the general formula (2) in the presence of water. can.

<Resin composition (S)>
The resin composition (S) of the present invention contains the epoxy resin (A), the curing agent (B) and the curing accelerator (C).
The resin composition (S) has excellent curability, and its cured product has excellent resin physical properties and excellent heat resistance. It can be used suitably as a use.

Based on the total weight of the epoxy resin (A) and the curing agent (B), the curing accelerator (C) is preferably 0.01 to 5% by weight, more preferably 0.05 to 4% by weight, particularly preferably 0.1 to 3% by weight.

Further, the weight ratio [(A)/(B)] of the epoxy resin (A) and the curing agent (B) is preferably 3/97 to 97/3 from the viewpoint of the balance between resin physical properties and heat resistance. More preferably 10/90 to 90/10, particularly preferably 25/75 to 75/25.

The resin composition (S) may contain an inorganic filler (D) for the purpose of improving the physical properties and heat resistance of the resin.
The inorganic filler (D) is preferably 50 to 1000% by weight, more preferably 70 to 500% by weight, particularly preferably 90 to 250% by weight, based on the total weight of the epoxy resin (A) and the curing agent (B). % by weight.
Examples of the inorganic filler (D) include known fillers such as silica and alumina. The shape and particle size of (D) vary depending on the purpose, but examples thereof include those having a median particle size of 5 to 50 μm and being almost spherical.

Moreover, the resin composition (S) may contain a known additive (E) in addition to the above (A), (B), (C) and (D).
The additive (E) includes flame retardants, antioxidants, and ion trapping agents, and the (E) is preferably 5% by weight or less, more preferably 0.1 to 3% by weight.

The resin composition (S) of the present invention can be produced, for example, by mixing the above (A), (B), (C), optionally an inorganic filler (D), and an additive (E).
The water content of the resin composition (S) of the present invention is preferably controlled to 1000 ppm or less.

<Cured product>
The cured product of the present invention is a cured product obtained by curing the resin composition (S). The curing conditions vary depending on the type and amount of the curing accelerator (C). For example, curing can be performed at a temperature of 150 to 200° C. and a time of 1 to 10 hours (h).

<Electronic parts>
The electronic component of the present invention is an electronic component sealed with a cured product of the resin composition (S). Examples of the electronic parts include semiconductors. In particular, it can be suitably used for electronic parts that require resin physical properties and heat resistance.

EXAMPLES Next, the present invention will be specifically described with reference to Examples, but the present invention is not limited to Examples unless it departs from the gist of the present invention. Unless otherwise specified, parts means parts by weight and % means % by weight.

<Production Example 1>
In a reaction vessel, 35.0 parts of phenylphosphonic acid [manufactured by Tokyo Kasei Kogyo Co., Ltd.] was dissolved in 30 parts of acetone, and 1,8-diazabicyclo(5,4,0)undecene-7 [manufactured by San-Apro Co., Ltd., product Name: DBU] 65.0 parts was gradually added and mixed by stirring for 30 minutes.
Next, acetone was distilled off under reduced pressure to obtain a curing accelerator (C-1).

<Production Example 2>
In a reaction vessel, 47.6 parts of ethyl phosphonate [manufactured by Tokyo Kasei Kogyo Co., Ltd.] was dissolved in 50 parts of acetone and 20 parts of ion-exchanged water. .
Next, acetone was distilled off under reduced pressure to obtain a curing accelerator (C-2).

<Production Examples 3, 4, 6, Comparative Production Example 1>
In Production Example 1, curing accelerators (C-3) and (C-4) were prepared in the same manner as in Production Example 1, except that the type and number of parts of the base and the type and number of parts of the phosphonic acid were according to Table 1. ), (C-6) and curing accelerator (C′-1) for comparative example were obtained.
<Production Example 5>
A curing accelerator (C-5) was obtained in the same manner as in Production Example 2 except that DBU was changed to DBN and the number of parts thereof and the number of parts of phosphonic acid were as shown in Table 1.

In addition, the raw materials in Table 1 are as follows.
DBN: 1,5-diazabicyclo[4,3,0]-nonene-5: [manufactured by San-Apro, trade name: DBN]

<Example 1>
In a container, 44 parts of bisphenol A dicyanate ester (B-1) ["CYSTER TA", manufactured by Mitsubishi Gas Chemical Co., Ltd.] and 1.0 part of the curing accelerator (C-1) obtained in Production Example 1 are added. , 100° C. for 1 hour, then 56 parts of phenol novolac type epoxy (A-1) [“JER152”, epoxy equivalent 176, manufactured by Mitsubishi Chemical Corporation] was added and stirred for 3 minutes.
Furthermore, 100 parts of silica particles (D-1) [Denka Fused Silica FB-950, manufactured by Denka] are added, stirred for 3 minutes, and then cooled to room temperature (25 ° C.) over 15 minutes to form a resin composition (S -1) was obtained.

<Examples 2 to 13, Comparative Examples 1 to 2>
In Example 1, resin compositions (S-2) to (S-13), (S'-1), (S'-1), (S'-2) was obtained.
The obtained resin composition was evaluated by the method described below. Table 2 shows the results.

In addition, each raw material in Table 2 is as follows.
Bisphenol E-type dicyanate ester (B-2): "LECY" [manufactured by LOZNA]
Bisphenol A type epoxy (A-2): "JER828" [epoxy equivalent 180, manufactured by Mitsubishi Chemical Corporation]
Alicyclic epoxy resin (A-3): "Celoxide 2021P" [epoxy equivalent 140, manufactured by Daicel]
Naphthalene type epoxy resin (A-4): "EPICLON HP-4032D" [epoxy equivalent 145, manufactured by DIC Corporation]
Curing accelerator (C'-2): 2-ethyl-4-methylimidazole (manufactured by Tokyo Chemical Industry Co., Ltd.)

<Curability>
A 20-ml test tube containing 4 g of the obtained resin composition (S) was placed in an oil bath at 180° C., and the curing time until gelation of the resin composition (S) was measured.

<Glass transition temperature, coefficient of linear expansion>
The obtained resin composition was cured by heating at 140° C. for 2 hours and further at 180° C. for 4 hours.
Based on the method described in JIS K 7197: 2012, the produced sheet-shaped cured product was processed into test pieces of 5 × 5 × 15 mm, and then the test pieces were subjected to a thermal dilatometer TMA8140C (Rigaku Corporation company). Then, the dimensional change of the test piece was measured between 25°C and 300°C by setting the heating rate to 5°C/min and applying a constant load of 19.6mN. The relationship between this dimensional change and temperature was plotted on a graph.
From the graph of dimensional change and temperature obtained in this way, two arbitrary temperature points at which the tangent line of the dimensional change-temperature curve can be obtained below the temperature of the inflection point are T ₁ and T ₂ , and the inflection point T ₁ ' and T ₂ ' are two arbitrary temperature points at which similar tangents are obtained above the temperature.
Let D ₁ and D ₂ be the dimensional changes at T ₁ and T ₂ , respectively, and point (T ₁ , D ₁ ) and point (T 2
, D ₂ ) and the dimensional changes at T ₁ ' and T ₂ ' as D ₁ ' and D ₂ ' respectively, points (T ₁ ', D ₁ ') and points (T ₂ ', D ₂ ') was taken as the glass transition temperature (T _g ). Also, the slope of T ₁ to T ₂ was defined as a coefficient of linear expansion below Tg.

<Measurement of 5% Weight Loss Temperature>
The obtained resin composition was cured by heating at 140° C. for 2 hours and further at 180° C. for 4 hours. After the cured product was processed into test pieces of 5×5×15 mm, the test pieces were set in a thermogravimetric analyzer Pyris 1 TGA (manufactured by PerkinElmer Japan).
Then, the temperature was set to rise at 5° C./min, and the temperature at which the weight of each test piece decreased by 5% (hereinafter referred to as 5% weight loss temperature) was measured from 25° C. to 550° C. under the atmosphere.

<Evaluation of cracks after high temperature storage>
The resulting resin composition was poured into a mold, placed on a silicon chip as a truncated cone-shaped test piece with an upper diameter of 2 mm, a lower diameter of 5 mm, and a height of 3 mm. for 4 h to cure. After curing, the obtained test piece was stored in an oven at 200 ° C. for 1000 hours, cooled to room temperature and cooled, a 1% aqueous solution of a fluorescent substance (uranin) was dropped on the test piece, and dried under reduced pressure. The piece was exposed to black light and the presence or absence of cracks was measured.

<Evaluation of viscosity increase rate>
The viscosity of the resulting resin composition after 10 minutes (hereinafter referred to as initial viscosity. Unit: mPa s) was measured for each composition at a set temperature of 25°C according to JIS Z8803 using an E-type viscometer. It was measured. In addition, the viscosity of the resin composition after being held at 25° C. for 12 hours was similarly measured to calculate the viscosity increase rate (unit: %).
where the viscosity increase rate is
Viscosity increase rate = [(viscosity after 12 hours) - (initial viscosity)] / (initial viscosity) x 100
Calculated by

From the results in Tables 1 and 2, it can be seen that the resin composition (S) of the present invention has excellent curability, and the cured product thereof has excellent resin physical properties and excellent heat resistance as compared with the comparative composition. .

The resin composition (S) of the present invention has excellent curability, and the cured product thereof has excellent resin physical properties and excellent heat resistance. It can be suitably used as a sealing material.

Claims (7)

It contains an epoxy resin (A), a curing agent (B) and a curing accelerator (C), and the curing agent (B) is a dicyclopentadiene type cyanate ester curing agent, a triazine skeleton-containing phenol curing agent, or a novolac type cyanate. It is at least one selected from the group consisting of an ester curing agent and a bisphenol-type cyanate ester curing agent, and the curing accelerator (C) is a phosphonic acid (ester) represented by the general formula (1) and the general formula A resin composition (S) which is a salt composed of a base represented by (2).

[In the general formula (1), R ¹ , R ² and R ³ are each independently a cyclohexyl group, a phenyl group, an alkyl group having 1 to 20 carbon atoms or a hydrogen atom, and R ¹ , R ² or R ³ At least one is a hydrogen atom. ]

[In general formula (2), m is an integer of 2 to 6, and a hydrogen atom of each methylene group may be substituted with an organic group. ] The epoxy resin (A) is a phenol novolak type epoxy resin, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, an alicyclic epoxy resin, a naphthalene type epoxy resin, a naphthol type epoxy resin, a biphenyl type epoxy resin, or a naphthylene ether. 2. The resin composition according to claim 1, wherein the resin composition is at least one selected from the group consisting of type epoxy resins, cresol novolac type epoxy resins, glycidyl ester type epoxy resins, anthracene type epoxy resins and epoxy resins having a butadiene structure. The resin composition according to claim 1 or 2, wherein the content of the curing accelerator (C) is 0.01 to 5% by weight based on the total weight of the epoxy resin (A) and the curing agent (B). thing. The resin composition according to any one of claims 1 to 3 , wherein the weight ratio [(A)/(B)] of the epoxy resin (A) and the curing agent (B) is 3/97 to 97/3. Furthermore, it contains an inorganic filler (D), and the content of said (D) is 50 to 1000% by weight based on the total weight of the epoxy resin (A) and the curing agent (B). 5. The resin composition according to any one of 1 to 4 . A cured product obtained by curing the resin composition (S) according to any one of claims 1 to 5 . An electronic component sealed with a cured product of the resin composition (S) according to any one of claims 1 to 5 .