JP3173820B2 - Phenol novolak resin containing allyl groups at both ends and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicone novolak block which is suitably used as a silicone flexible agent effective for lowering the stress of a semiconductor element encapsulant containing an epoxy resin as a base resin and also as a resist material. The present invention relates to a phenol novolak resin containing allyl groups at both ends required for producing a copolymer and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, the degree of integration of semiconductor devices has been remarkably increased, and accordingly, the size of the devices has been increased. In view of high-density mounting, there has been a demand for smaller and thinner packages. These technical trends cause problems such as package cracks in the conventional semiconductor element encapsulant, and there is currently a demand for even lower stress in the encapsulant.

[0003] There are two methods for lowering the stress of the sealing material, that is, lowering the expansion coefficient and lowering the elastic modulus. The former is achieved mainly by adding a filler such as fused silica. In the latter case, the use of a flexible agent is mainly effective. At this time, if the compatibility between the base resin such as an epoxy resin and the flexible agent is good, the glass transition point (Tg) decreases and the heat resistance decreases. Induces undesirable. To achieve both low stress and high heat resistance, PVC-
It is effective to construct a sea-island structure in which a flexible agent component is dispersed in a resin such as a nitrile rubber system or an ABS resin system. As a result of various studies on a flexible agent for an epoxy resin which is a main material of a sealing material resin, a silicone resin is most excellent in dispersibility, and in order to achieve low stress while maintaining heat resistance. Have been found to be effective flexibilizers.

[0004] As a silicone flexible agent, an additive-type flexible agent in which silicone oil is simply added to a base resin was initially developed. However, problems such as poor appearance due to exudation of silicone and unfavorable molding occurred. Therefore, a resin-modified flexible agent was developed in which a silicone resin containing a reactive functional group was previously reacted with a base resin in order to suppress this exudation, further improve dispersibility, and improve stress reduction. . As the resin-modified silicone flexible agent, various silicone-modified epoxy resins (JP-A-62-84147, etc.), silicone-modified phenolic resins (JP-B-61-48544, etc.) and the like have been studied.

[0005]

Some of the resin-modified silicone flexible agents developed so far have achieved both low stress and high heat resistance, but at the same time have satisfactory mechanical strength. There was nothing to make. It is effective to increase the elongation of the resin to increase the strength, and to achieve this, it is effective to construct a dense microphase separation structure in the resin. For this purpose, a molecular design is required in which the silicone flexible agent is a silicone-novolak (epoxy) block copolymer, particularly a multi-block copolymer.

[0006] Among the conventional flexible agents, various types of silicone-modified phenolic resins have been proposed, but those synthesized by using a phenolic hydroxyl group in a copolymerization reaction have a molecular structure of a block copolymer. Is hard to say. In addition, what is synthesized from a prepolymer obtained by copolycondensation of phenol and allylphenol described in JP-B-61-48544 is a complete block copolymer because novolak has some branching. Without limitation, it is inevitable that the resulting product is a mixture of a triblock copolymer, a diblock copolymer, and a homopolymer. Further, there is a problem that a multi-block copolymer that can construct a dense phase-separated structure most stably cannot be synthesized. It was not possible to synthesize a complete silicone-novolak multiblock copolymer by this known example or any of the synthesis methods known so far.

Considering that the synthesis of a silicone-novolak block copolymer is achieved by the reaction of a polysiloxane with a novolak resin, it is necessary to synthesize a complete block copolymer or even a multi-block copolymer. In addition, telechelic polysiloxane and telechelic novolak resin are required as both macromonomer components.
The former can be easily synthesized by a known technique, but the latter requires a special molecular design and synthesis technique.

An object of the present invention is to provide a telechelic novolak resin required for synthesizing the silicone-novolak multiblock copolymer.

[0009]

Means for Solving the Problems The present inventors have proposed a telechelic polysiloxane having Si-functional groups at both ends as functional groups.
Assuming a polysiloxane having an H group, a complete block is obtained by subjecting a telechelic phenol novolak resin having an allyl group only at both ends as a functional group having reactivity to a Si-H group to a condensation reaction with the telechelic polysiloxane. The present invention has been completed by focusing on the fact that a multi-block copolymer can be synthesized. That is, the present invention relates to a phenol novolak resin containing allyl groups at both ends represented by the following formula [I] (wherein R ₁ represents an alkyl group having 1 to 4 carbon atoms, and R ₂ represents 1 to 4 carbon atoms) In which n is a number of 5 to 10 on average).

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In order to synthesize the telechelic novolak resin of the present invention, it is necessary to consider the following two designs. 1. 1. Synthesis of linear novolak resin Introduction of functional groups at both ends

The first design is achieved by selecting a bifunctional (two formaldehyde active sites) phenol compound as a monomer when synthesizing a novolak resin.

The design of the second point is based on the design of the first point. That is, a novolak resin synthesized from a bifunctional phenol does not have a formaldehyde active site in its molecular chain, but has an active site only at the molecular chain terminal. That is, by converting this novolak resin into methylol under appropriate conditions, a reactive methylol group can be introduced into both ends of the molecular chain. Next, the methylol group-containing novolak resin at both ends is condensed with a monofunctional phenol compound having a reactive functional group (one capable of reacting with the functional group of polysiloxane) under appropriate conditions to react at both ends. A functional group can be introduced.

Thus, the synthesis of the telechelic novolak resin becomes possible, and the reaction with the telechelic polysiloxane makes it possible to synthesize a complete silicone-novolak block copolymer and a multi-block copolymer. In the present invention, Si-
Assuming an H group, an allyl group was used as a functional group of the target telechelic novolak resin.

That is, the present invention relates to a phenol novolak resin represented by the following formula [II] (wherein R ₁ is an alkyl group having 1 to 4 carbon atoms, and n is a number of 5 to 10 on average) Is reacted with formaldehyde in a solvent in the presence of an alkali catalyst to form methylol at both ends to obtain a phenol novolak resin having a methylol group at both ends represented by the following formula [III]. Wherein the resin and an allylphenol represented by the following formula [IV] are condensed in a solvent in the presence of an acid catalyst, and a phenol novolak resin having both terminal allyl groups represented by the following formula [I] (wherein: R ₂ represents an alkyl group or an alkoxyl group having 1 to 4 carbon atoms).

[0015]

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[0016]

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[0017]

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[0018]

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R ₁ represents an alkyl group having 1 to 4 carbon atoms, and among them, a methyl group is preferable. R ₂ has 1 to 1 carbon atoms
4 represents an alkyl group or an alkoxyl group, among which a methoxy group and a methyl group are preferable.

The production method of the present invention will be described in more detail. A linear phenol novolak resin represented by the formula [II] is used as a starting material, and a phenol containing an allyl group at both ends is obtained by the following two-step reaction. Novolak resin synthesis is achieved. First step: Methylolation reaction of both ends of phenol novolak resin Second step: Condensation reaction of phenol novolak resin containing both ends methylol group with allylphenol

The linear phenol novolak resin represented by the formula [II] is obtained by converting a phenol compound represented by the following formula [V] (wherein R ₁ has the same meaning as described above) and formaldehyde using an acid catalyst. It can be obtained by condensation.

[0022]

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The phenol compound represented by the formula [V] is a bifunctional phenol compound having an R ₁ group in addition to a hydroxyl group as a core substituent and having two formaldehyde active sites. The novolak resin becomes a linear phenol novolak resin, and has a formaldehyde active site only at the molecular chain terminal.
As the phenol compound, for example, o-cresol, p-cresol and the like are suitably used. As formaldehyde, paraformaldehyde, formalin, formaldehyde gas and the like are preferably used, and as the acid catalyst, oxalic acid, hydrochloric acid and the like are suitably used. F / P (formaldehyde / phenol compound charge ratio) is 0.5 to 0.9, preferably 0.6 to 0.
It is preferably 75. The catalyst concentration is preferably 0.1 to 2.0% by weight based on the phenol compound. Also,
The reaction temperature is preferably from 80 to 110 ° C, and the reaction time is preferably from 6 to 8 hours.

The phenol novolak resin used in the present invention can be obtained in this manner, and n is 5 to 5 on average.
10, but in a number average molecular weight of 600 to 1200.
Is preferably used.

In the first step of the production method of the present invention, the phenol novolak resin represented by the formula [II] thus obtained is methylolated with formaldehyde in a solvent using an alkali catalyst, and then converted to a compound represented by the formula [III]. The novolak resin having a methylol group at both ends shown is obtained. At this time, since the formaldehyde active site of the phenol novolak resin is located only at the molecular chain terminals, only the molecular chain terminals are surely converted to methylol. As formaldehyde, paraformaldehyde, formalin, formaldehyde gas and the like are preferable, and as a reaction solvent, an alcoholic solvent such as methanol and ethanol is preferable. As the alkali catalyst, sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide and the like are preferably used.

As the reaction conditions in the first stage, the amount of formaldehyde charged is 1 to the product of the number of moles of the phenol novolak resin and the number of the phenol novolak resin represented by n in the formula [II]. It is preferable that the number of moles be 10 to 10 times the number of moles. The solution concentration, that is, the ratio of the amount of the phenol novolak resin to the total amount of the solvent and the phenol novolak resin is preferably 2 to 40% by weight, and the catalyst concentration is preferably 0.5 to 2N. The reaction temperature is preferably from room temperature to 60 ° C., and the reaction time is preferably from 2 to 6 hours. In the second stage reaction, the phenol novolak resin having a methylol group at both ends represented by the formula [III] synthesized in the first stage and allylphenol represented by the formula [IV] are condensed in a solvent using an acid catalyst. By doing so, a phenol novolak resin containing allyl groups at both ends represented by the formula [I] is obtained.

The allyl phenol used in the present invention has an R ₂ group in addition to an allyl group as a nucleus substituent and has one active site for formaldehyde in order to surely introduce the phenol novolak resin at the terminal. Certain monofunctional ones are used. That is, it is used as an end-blocking agent. Preferable specific examples of the allylphenol represented by the formula [IV] include 4-allyl-2-methoxyphenol, 2-allyl-4-methylphenol, 2-allyl-6-methylphenol and the like. As a reaction solvent, dioxane, methyl isobutyl ketone and the like are suitably used. Acid catalysts include hydrochloric acid, sulfuric acid, oxalic acid,
P-toluenesulfonic acid and the like are preferred.

The reaction conditions in the second stage are as follows: the amount of allylphenol charged is determined by the number of moles of the phenol novolak resin having a methylol group at both ends represented by <U> formula [III] </ U> and the number of moles of the phenol novolak resin. It is preferable that the molar number is 1 to 10 times the number of products of the product represented by n in the formula [III]. Further, the solution concentration, that is, the ratio of the amount of the phenol novolak resin containing both ends methylol groups to the solvent is preferably 0.1 to 1 mol / l, and the catalyst concentration is preferably 1/10 to 1/200 mol of allylphenol. . The reaction temperature is 80 to 110 ° C,
The reaction time is preferably from 1 to 3 hours.

By polycondensing the thus obtained phenol novolak resin containing allyl groups at both ends with telechelic polysiloxane, a silicone-novolak multiblock copolymer can be reliably obtained. By using a block copolymer as a flexible agent for a semiconductor encapsulant, it is possible to obtain an encapsulant with reduced stress and high heat resistance and high strength.

[0030]

【Example】

Example 1 (Synthesis of o-cresol novolak resin) 500 g (4.63 mol) of o-cresol and 113 g (3.24 mol) of paraformaldehyde were placed in a 1-liter separable flask equipped with a stirrer, a condenser, and a thermometer. Was added, and the mixture was stirred and heated to 50 ° C., and 4.9 g of oxalic acid was added. Thereafter, the mixture was heated to 100 ° C. and stirred for 6 hours. After the completion of the reaction, unreacted o under the conditions of 100 to 160 ° C./30 mmHg.
-Cresol was completely removed under reduced pressure. Complete removal is GPC
Confirmed by

Confirmation of synthesis¹³C-NMR spectrum measurement
Was performed. 1 of the resin obtained in FIG. ^{1 Three}C-NMR cha
Indicates the port number.

The obtained resin has n of 8 on average and a number average molecular weight of 960, and the yield is 483 g (99 yield).
%), The shape was a yellow transparent solid.

(Synthesis of o-cresol novolak resin containing methylol groups at both ends) 200 g of o-cresol novolak resin previously synthesized in a 3-liter separable flask equipped with a stirrer, a cooling tube, a thermometer, and a dropping funnel.
(3.70 × 10 ⁻¹ mol) and 32 g of sodium hydroxide were added, and 800 g (1010 ml) of methanol was added thereto, followed by stirring to completely dissolve. Thereafter, the mixture was heated to 50 ° C., and 1400 g (16.3 mol) of 35% formaldehyde solution (formalin) was added to this solution from a dropping funnel for about 1 hour.
It was dropped over time. After completion of the dropwise addition, the mixture was stirred for 4 hours while maintaining the reaction temperature at 50 ° C. After completion of the reaction, the reaction solution was carefully neutralized with acetic acid, and then poured into a large amount of distilled water to precipitate a crude product. After the precipitate was separated by filtration, the precipitate was washed three times with distilled water, and reprecipitated three times with acetone (good solvent) / distilled water (poor solvent). Thereafter, vacuum drying was performed at room temperature.

[0034] Confirmation of the completion of the reaction by measuring the ¹³ C-NMR spectrum, 115 and terminal unreacted ortho-position of 120 ppm, complete disappearance and signals for para carbon 6
Performed with the appearance of a 3 ppm methylol carbon signal. FIG. 2 shows a ¹³ C-NMR chart of the obtained resin.

The obtained resin had a yield of 132 g (a yield of 60 g).
%), The shape was a reddish brown solid.

(Synthesis of o-cresol novolak resin containing allyl groups at both ends) 4-allyl-2-methoxyphenol (eugenol) 274 was placed in a 2-liter separable flask equipped with a stirrer, a condenser, a thermometer, and a dropping funnel.
g (1.67 mol), 420 ml of 1,4-dioxane,
Hydrochloric acid (1.69 g, 1.67 × 10 ^-2 mol) was added and 10
The mixture was stirred under reflux at 1 ° C. 100 g of an o-cresol novolak resin containing a methylol group at both ends previously synthesized in this solution
(1.12 × 10 ^-1 mol) in 1,4-dioxane 500
solution dissolved in 100 ml / 3 drops from the dropping funnel.
Carefully dropped at a rate of 0 minutes. After completion of the dropwise addition, reflux stirring was performed for 1 hour. After the reaction, 200 ° C / 30mmHg
Under the conditions described above, unreacted eugenol was completely removed under reduced pressure.
Complete removal was confirmed by GPC.

The completion of the reaction was confirmed by measuring the ¹³ C-NMR spectrum and confirming the complete disappearance of the signal relating to methylol carbon at 63 ppm, the appearance of a signal relating to methoxy carbon at 59 ppm, and the appearance of a signal relating to an allyl group at 115 to 120 ppm. FIG. 3 shows a ¹³ C-NMR chart of the obtained resin.

The average composition of the resin, that is, the average value of n is 8
(Allyl phenol is bonded to both terminals of the repeating unit 8 of o-cresol) was determined by measuring its ¹ H-NMR spectrum.

The obtained resin had a yield of 99 g (a yield of 76 g).
%), And the shape was a black solid. ¹³ C-N of each stage
From the change in the MR spectrum, the synthesis of o-cresol novolak resin containing allyl groups at both molecular chain terminals was confirmed.

[0040]

The phenol novolak resin containing allyl groups at both ends of the present invention is a telechelic novolak resin having allyl groups active in hydrosilylation reaction at both ends of the molecule. And a hydrosilylation reaction, a silicone-novolak multi-block copolymer can be synthesized.
When this silicone-novolak multi-block copolymer is used as a flexible agent for a semiconductor encapsulant, a dense phase-separated structure can be formed in the resin, and as a result, low stress, high heat resistance, and high strength encapsulation can be achieved. Materials can be designed.

[Brief description of the drawings]

FIG. 1 is a ¹³ C-NMR chart of an o-cresol novolak resin synthesized in Example 1.

FIG. 2 shows an o-containing methylol group at both ends synthesized in Example 1.
1 is a ¹³ C-NMR chart of a cresol novolak resin.

FIG. 3 is a ¹³ C-NMR chart of an o-cresol novolak resin containing allyl groups at both ends synthesized in Example 1.

Claims (4)

(57) [Claims] 1. A phenol novolak resin containing allyl groups at both terminals represented by the following formula [I] (wherein R ₁ represents an alkyl group having 1 to 4 carbon atoms, and R ₂ represents 1 to 4 carbon atoms).
Represents an alkyl group or an alkoxyl group, wherein n is an average of 5
It is a number from 10 to 10. ). Embedded image 2. A phenol novolak resin represented by the following formula [II] (wherein R ₁ represents an alkyl group having 1 to 4 carbon atoms, and n is an average of 5 to 10). In the presence of an alkali catalyst, both ends are converted to methylol by reacting with formaldehyde in the presence of an alkali catalyst to obtain a phenol novolak resin having a methylol group at both ends represented by the following formula [III]. A phenol novolak resin having both allyl groups at both ends represented by the following formula [I], wherein R ₂ is 1 carbon atom
4 represents an alkyl group or an alkoxyl group. ) Manufacturing method. Embedded image Embedded image Embedded image Embedded image 3. The production conditions for the phenol novolak resin having a methylol group at both ends represented by the formula [III] are as follows: the amount of formaldehyde charged is the number of moles of the phenol novolak resin represented by the formula [II]; II] with the number represented by n in
1 to 10 times the number of moles, the ratio of the amount of the phenol novolak resin to the total amount of the solvent and the phenol novolak resin is 2 to 40% by weight, the reaction temperature is room temperature to 60 ° C, and the reaction time is 2 to 6 hours. The production method according to claim 2, wherein 4. A method for producing a phenol novolak resin having an allyl group at both ends represented by the formula [I], wherein the preparation amount of allylphenol represented by the formula [IV] is a phenol having a methylol group at both ends represented by the formula [III]. The number of moles of the novolak resin and the formula [II
I] 1 to 10 times the number of moles of the phenol novolak resin having a methylol group at both ends with respect to the solvent, with respect to the product of the product of n and the number represented by n in I].
The production method according to claim 2, wherein the amount is liter.