JP2002327035A - Phenolic polymer, its production method, curing agent for epoxy resin, epoxy resin composition for semiconductor sealing and semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phenolic polymer having low melt viscosity, high glass transition temperature and excellent curing characteristics which is suitable as an epoxy resin curing agent for the semiconductor sealing and the insulation of a printed board or the like. SOLUTION: (1) The phenolic polymer having the melt viscosity at 150 deg.C of 50-300 mPa.s which is represented by the formula Ph(OH)-[CH2 -(Ph) OH]m -[CH((PH)OH)((PH)OH)]n (wherein, Ph is a residue to a benzene nucleus such as a phenyl, phenylene or the like; m/m is 0.7/1-1.5/1; the site of substitution of the CH2 group to OH group is p/o position and 2.0 or more). (2) The method for producing the polymer by reacting the phenols at the rate of 3.0 mole or more with respect to the total 1 mol of salicyl aldehyde and formaldehyde at <=70 deg.C. (3) The curing agent for an epoxy resin which comprises the polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to various binders,
The present invention relates to a phenolic polymer useful for a coating material, a laminate, a molding material, and the like, a method for producing the same, and a curing agent for an epoxy resin using the same. Particularly suitable for epoxy curing agents for semiconductor encapsulation, printed circuit board insulation, etc., low melt viscosity,
The present invention relates to a phenolic polymer having a high glass transition temperature and excellent curing properties, and a method for producing the same.

The present invention also provides a curing agent for an epoxy resin comprising the above-mentioned phenolic polymer, an epoxy resin composition containing the same and an epoxy resin, and a semiconductor element encapsulated with the epoxy resin composition. The present invention relates to a semiconductor device.

[0003]

2. Description of the Related Art Various phenolic polymers such as phenol novolak type resins and phenol aralkyl resins have been used as epoxy resin curing agents for electronic materials, particularly for encapsulating semiconductors and for insulating printed boards. However, in recent years, with the miniaturization and thinning of the semiconductor package, the increase in the number of pins, and the high-density mounting, a resin with higher performance has been required.

One of the important physical properties of a phenolic polymer for use as an encapsulant for semiconductor devices is that it has a high glass transition temperature. As a means for increasing the glass transition temperature, it is effective to increase the hydroxyl group concentration, and for this reason, a so-called polyfunctional type is often used. A typical example thereof is a triphenolmethane-type phenol resin represented by the following formula (2) (Japanese Patent Publication No. 7-121979, Japanese Patent Application Laid-Open No. 2-173023).

[0005]

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[0006] These triphenolmethane-type phenol resins are characterized by having a high glass transition temperature and therefore being excellent in various reliability. In addition, BGA (Ball
When used in a single-sided sealed package such as a GridArray, the package has excellent performance in that the package is small in warpage. However, in recent semiconductor packages, for example, in the case of BGA, it is required to be further refined or packaged in a package, and to have a small warpage, high fluidity, good adhesion to a substrate surface, and the like. I have. Further, in packages such as SOP, QFP, and DIP, low viscosity is strongly desired in view of elongation of the wire length, reduction of the wire diameter, and miniaturization. If the melt viscosity is low, the fluidity and adhesion are improved, and a large amount of filler can be added, which is advantageous in terms of solder heat resistance and water resistance. That is, in order to satisfy the required properties of these sealing materials, the appearance of a phenolic polymer (curing agent) having both a high glass transition temperature, a low melt viscosity and excellent curability is strongly desired.

In addition, the interlayer insulating material of the build-up substrate
An epoxy resin composition having excellent water resistance and good adhesiveness at a high glass transition temperature is desired, and in order to achieve this,
A phenolic curing agent which is originally excellent in water resistance and storage stability and which has both high glass transition temperature, low melt viscosity and excellent curability is desired.

However, if the concentration of hydroxy groups is increased to increase the glass transition temperature, the melt viscosity increases due to hydrogen bonding between the hydroxy groups. As a result, the fluidity is poor due to an increase in the melt viscosity, which causes molding problems such as wire deformation. When the molecular weight is reduced or the hydroxyl group concentration is reduced to lower the melt viscosity, the glass transition temperature is lowered and the curability at the time of molding is lowered. That is, it is considered that it is theoretically difficult to achieve both a high glass transition temperature, a low melt viscosity, and curability.

A resin in which an allyl group is added to a triphenolmethane-type phenol resin has also been proposed (JP-A-4-23824). These resins have a high glass transition temperature and thus have a small heat shrinkage, and have a large free volume as a resin skeleton, and therefore have a small cure shrinkage, which is said to contribute to low warpage. However, this type of resin is still insufficient to the required level because the glass transition temperature and the curability also decrease as the amount of allyl groups introduced increases.

As a method of solving these problems, the present inventors have shown that a triphenolmethane polymer unit and a phenol novolak polymer unit are both present in the molecule as shown in the following formula (3). Then, a phenolic polymer in which the ratio of the degree of polymerization of both and the melt viscosity are in specific ranges has been proposed (Japanese Patent Application No. 2002-3645).

[0011]

Embedded image (Where m / n is 0.7 to 1.5, and R ¹ , R ² , R
³ and R ⁴ are a hydroxy group or an alkyl group, p,
q, r and s are 0-2. )

[0012]

SUMMARY OF THE INVENTION An object of the phenolic polymer and a high glass transition temperature, curable at a low melt viscosity ratio
Although it is relatively good and has excellent properties as an epoxy resin curing agent, an epoxy resin curing agent is required to have further excellent curability such as curing speed. Therefore, the present inventors
By further improving the above-mentioned phenol resin and setting the ratio of the p / o position of the methylene group-substituted position to the hydroxy group in the phenol novolak polymerized unit to a specific range, it has a low melt viscosity and a high glass transition temperature. In addition, a phenolic polymer having better curability can be obtained, and by using such a phenolic polymer as an epoxy resin curing agent, it has excellent properties such as molding curability and heat resistance for semiconductor encapsulation. The present inventors have found that an epoxy resin composition can be obtained, and have completed the present invention.

[0013]

The present invention relates to a phenolic polymer represented by the following general formula (1):
A phenolic polymer having a melt viscosity at 50 ° C. of 50 to 300 mPa · s and a methylene group substitution position with respect to a hydroxy group in a phenol novolak polymerization unit of 2.0 or more at a p / o position. is there.

[0014]

Embedded image (In the formula, m / n is 0.7 to 1.5, R ¹ , R ² , R ³ and R ⁴ are alkyl groups, and p, q, r and s are 0 to 2.)

Further, the present invention provides a step-wise condensation reaction of phenols, salicylaldehydes and formaldehyde at a temperature of 70 ° C. or lower, preferably in the presence of an acid catalyst. And a method for producing a phenolic polymer represented by the above formula (1), wherein the phenolic polymer is removed.

Further, the present invention provides a curing agent for an epoxy resin comprising a phenolic polymer represented by the above formula (1), an epoxy resin composition for encapsulating a semiconductor containing the same, and the use of the epoxy resin composition. This is a semiconductor device in which a semiconductor element is sealed.

[0017]

DETAILED DESCRIPTION OF THE INVENTION The phenolic polymer of the present invention has the formula
(1) is a copolymerized phenolic polymer having n polymerization units of a triphenolmethane-type resin represented by (n) and m polymerization units of a phenol novolak resin, represented by the formula (1)
In the above, the ratio m / n of the degree of polymerization of each polymerization unit is 0.7 to 1.5, preferably 0.9 to 1.4. The melt viscosity at 150 ° C. is 50 to 300 mPa · s, preferably 50 to 200 mPa · s.
mPa · s. As having such a melt viscosity, the degree of polymerization n and m of each polymerization unit is usually 0 to 1
A mixture of polymers having an average degree of polymerization of 0.6 to 2.
0, preferably 0.8 to 1.4 is used.

When the degree of polymerization is high and the melt viscosity is higher than the above range, the fluidity decreases. Further, those having a lower molecular weight and a lower melt viscosity are not preferred because the glass transition temperature becomes lower.

Incidentally, JP-A-63-22824 discloses that
It describes a copolymer of a triphenolmethane resin and a phenol novolak resin, but does not disclose a copolymer having a low melt viscosity as in the present invention. Particularly under polymerization conditions as shown as specific examples, the degree of polymerization is large, and the melt viscosity at 150 ° C. is 300 mPa ·
Only a resin that greatly exceeds s is obtained, and does not achieve the object of the present invention.

In the phenolic polymer of the present invention, when m / n exceeds 1.5, the glass transition temperature decreases, and the curing speed also decreases. On the other hand, if m / n is less than 0.7, the melt viscosity increases and the fluidity deteriorates.

The phenolic polymer of the present invention has a structure in which polymerized units of a triphenolmethane resin and a phenol novolak resin are both present in a specific ratio in a molecule,
As a result, a polymer suitable for an epoxy curing agent and having a low melt viscosity, a high glass transition temperature, and excellent curability is obtained.

The phenolic polymer of the present invention also has a polymerized unit of a phenol novolak resin in the molecule as shown in the formula (1), and the benzene nucleus has a hydroxy group and an adjacent phenol novolak polymerized unit. And a methylene group that binds to The present invention is characterized in that the substitution position of the methylene group with respect to the hydroxy group is 2.0 or more in p / o ratio.

The phenolic polymer of the present invention has a low melt viscosity as described above by setting the position of the methylene group substitution at the p / o position to 2.0 or more, preferably 2.5 to 3.5.
In addition to the property of high glass transition temperature, the curing time is shorter and the conversion at the beginning of the reaction is particularly high, which is industrially advantageous.

The p / o ratio of the methylene group substitution position with respect to the hydroxy group can be measured by ¹ H-NMR spectroscopy.

The phenolic polymer of the present invention can be widely used for applications such as binders, coating materials, laminates, molding materials, etc., especially when it has a low melt viscosity, a high glass transition temperature and excellent curing properties. Therefore, it is particularly suitable for epoxy curing agents for semiconductor encapsulation, printed circuit board insulation, and the like.

[Production of phenolic polymer] The phenolic polymer represented by the above formula (1) used in the present invention is exemplified by a case where phenol is used as phenol and salicylaldehyde is used as salicylaldehyde. Then, it can be produced by condensing phenol, salicylaldehydes and formaldehyde in the presence of an acid catalyst according to the following formula (4).

[0027]

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The condensation reaction can be carried out by adding salicylaldehydes and formaldehyde all at once. In this case, the total amount of salicylaldehydes and formaldehyde is 1 mole, and phenol is preferably 3.0 moles or more, and more preferably 3.0 moles. While used in the range of 3 to 10.0 mol,
By using a large amount of an acid catalyst and lowering the reaction temperature to 70 ° C. or lower, the reaction between phenol and formaldehyde is preferentially performed to form a low molecular weight phenol novolak resin. Next, a condensation reaction of salicylaldehydes and phenols occurs, and the phenolic polymer of the present invention is obtained. In this case, too, the p / o ratio at the methylene substitution position must be 2.0 or more. The reaction is preferably carried out at a temperature of 70 ° C. or lower. In order to promote the condensation reaction between salicylaldehydes and phenols at such a low temperature, it is desirable to increase the amount of the acid catalyst during the reaction. Total of salicylaldehydes and formaldehyde 1
When the amount of the phenol used is less than 3.0 moles per mole or the reaction temperature exceeds 70 ° C., the above-mentioned reaction conditions are not satisfied. Only a phenolic polymer having a small o ratio can be obtained.

The phenolic polymer of the present invention is obtained by condensing phenol and formaldehyde in the presence of an acid catalyst to form a phenol novolak resin in advance, as shown by the formula (5), in addition to the above batch addition method. Then, as shown in the formula (6), salicylaldehydes may be added, and the reaction may be carried out in the form of a two-stage reaction in which salicylaldehydes and phenols are condensed in the presence of the phenol novolak resin and an acid catalyst. In this case, as in the case of the batch addition method,
In the first-stage reaction, a large amount of an acid catalyst is used, the reaction temperature is lowered to 70 ° C. or lower, and the reaction between phenol and formaldehyde is carried out. The reaction has a low molecular weight and a p / o ratio of methylene substitution position of 1. Form zero or more phenolic novolak resins. Next, in the second-stage reaction, salicylaldehydes and phenols are added in the presence of an acid catalyst and a phenol novolak resin, and the reaction is carried out at a temperature of 70 ° C. or less at which the p / o ratio at the methylene substitution position becomes 2.0 or more. It is important that In the second-stage reaction, phenol can be added as necessary. However, the total amount of phenols added in the first and second stages should be 2.0 mol or more per 1 mol of salicylaldehyde. Is preferred.

[0030]

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[0031]

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For example, in the first-stage reaction, phenols are added in an amount of 2.5 mol or more per 1 mol of formaldehyde.
Preferably, 3.3 to 10.0 moles of salicylaldehyde and phenol are added in the second-stage reaction, and phenol is added to the total of 1 mole of salicylaldehyde and formaldehyde charged in the first to second stages. Is important to be used in an amount of 3.0 mol or more, preferably 3.3 to 10.0 mol. Even if the reaction conditions are deviated, only a phenolic polymer having a high molecular weight, a high melt viscosity and a small p / o ratio can be obtained.
When the reaction is carried out by such a two-stage addition method, the degree of polymerization of each polymerized unit of the triphenylmethane type resin and the phenol novolak resin, that is, the distribution of n and m becomes narrow, the molecular weight can be easily controlled, and the desired melting can be achieved. It is preferable for the purpose of the present invention because a polymer having a viscosity is easily obtained.

In the production of the phenolic polymer of the present invention, while controlling the amounts of phenols, salicylaldehydes and formaldehyde used as raw materials,
By adopting the reaction conditions as described above, the desired melt viscosity at 150 ° C., the polymerization degree ratio m / n of each polymerization unit, and the desired p of the methylene group substitution position with respect to the hydroxy group in the phenol novolak polymerization unit are obtained. / O
A polymer having a ratio can be obtained. The amount of the acid catalyst used in the batch addition reaction and the two-stage reaction varies depending on the type thereof, but is about 0.1 to 2.0% by weight in the case of oxalic acid and 0.01 to 4.0 in the case of hydrochloric acid. % By weight, and 0.002 to trifluoromethanesulfonic acid.
It is preferable to use about 0.01% by weight. In particular, when a two-stage reaction is carried out, when salicylaldehydes in the second stage are reacted with phenols and phenol novolak, it is preferable to use hydrochloric acid or trifluoromethanesulfonic acid. The reaction temperature is desirably 70 ° C. or lower in both the batch addition reaction and the two-stage reaction.

After condensing phenols, formaldehyde and salicylaldehyde in the presence of an acid catalyst, the unreacted phenols and acid catalyst are removed.
The phenolic polymer of the present invention can be obtained. The method of removing phenols is generally a method in which heat is applied under reduced pressure or while blowing an inert gas to distill phenols out of the system. There is also a method of removing the acid catalyst by washing such as water washing.However, when a volatile acid is used, a method of removing it out of the system by distillation together with phenols shortens the reaction process and increases the pot efficiency. This is preferable in that respect.

As phenols, besides phenol, for example, alkyl phenols such as cresol, ethyl phenol, propyl phenol, butyl phenol, hexyl phenol and nonyl phenol can be used, and phenol is particularly preferred. When using an alkylphenol, it is preferable to use an o- or m-alkylphenol.

As salicylaldehydes, in addition to salicylaldehydes, alkyl-substituted salicylaldehydes and the like can be used, and it is particularly preferable to use salicylaldehydes. Also p-
It can be used in combination with hydroxybenzaldehyde.

Further, as formaldehyde, 37%
Aqueous formaldehyde solution and paraformaldehyde,
A polymer that is decomposed into formaldehyde in the presence of an acid such as trioxane can be used.

The acid catalyst is not particularly limited, and known catalysts such as hydrochloric acid, oxalic acid, trifluoromethanesulfonic acid, sulfuric acid, phosphoric acid and p-toluenesulfonic acid can be used alone or in combination of two or more. Hydrochloric acid, oxalic acid or trifluoromethanesulfonic acid is particularly preferred. These catalysts have a high catalytic activity, and after the reaction is completed, the unreacted phenol, salicylaldehyde,
Since the catalyst can be removed together with formaldehyde, a washing step such as washing with water is not required.

[Curing Agent for Epoxy Resin, Epoxy Resin Composition for Encapsulating Semiconductor] The phenolic polymer of the present invention is used as a curing agent for epoxy resin. That is, an epoxy resin (A), a phenolic polymer (B) as a curing agent, an inorganic filler (C), and a curing accelerator (D) are essential components, and these components are mixed and kneaded to form a semiconductor seal. An epoxy resin composition for stopping is obtained.

[Epoxy Resin] Epoxy resins used for semiconductor encapsulation include cresol novolak type epoxy resin, triphenolmethane type epoxy resin, biphenyl type epoxy resin, dicyclopentadiene type epoxy resin, naphthol type epoxy resin and the like. It is preferably used. The mixing ratio of the phenolic polymer to the epoxy resin is preferably from 0.8 / 1.2 to 1.2 / 0.8 as hydroxyl equivalent / epoxy equivalent.

[Inorganic filler] Examples of the inorganic filler include amorphous silica, crystalline silica, alumina, glass, calcium silicate, gypsum, calcium carbonate, magnesite, clay, talc, mica, magnesia, barium sulfate and the like. Examples thereof include amorphous silica and crystalline silica. The amount of the inorganic filler used is 50% or more, more preferably 70 to 92% by weight of the entire epoxy resin composition for semiconductor encapsulation. If the content is less than 50% by weight, the effect of adding a filler such as water absorption and thermal expansion coefficient is significantly reduced. On the other hand, if it exceeds 92%, the physical properties as a semiconductor encapsulant deteriorate, such as an increase in fluidity.

[Curing Accelerator] As the curing accelerator, a known curing accelerator for curing an epoxy resin with a phenolic curing agent can be used. Examples of such curing accelerators include organic phosphine compounds and their boron salts, tertiary amines, quaternary ammonium salts, imidazoles and their tetraphenylboron salts, and among them, curability and moisture resistance In view of this, triphenylphosphine and 1,8-diazabicyclo (5,4,0) undecene-7 (DBU) are preferred.
Further, in order to obtain higher fluidity, a heat latent curing accelerator which exhibits activity by heating is more preferable, and a tetraphenylphosphonium derivative such as tetraphenylphosphonium / tetraphenylborate is preferable.

[Other Additives] The epoxy resin composition of the present invention may contain, if necessary, a release agent such as paraffin or an aliphatic ester, a flame retardant such as antimony trioxide or a phosphorus compound, and a flame retardant auxiliary. Colorants such as carbon black and titanium oxide, low stress agents such as silicone rubber and olefin rubber, and coupling agents such as silane coupling agents can be used. The amount used may be the same as the amount used in the conventional epoxy resin composition for semiconductor encapsulation.

[Preparation of Epoxy Resin Composition for Semiconductor Encapsulation] In order to produce an epoxy resin composition for semiconductor encapsulation, a phenolic polymer, an epoxy resin, an inorganic filler, a curing accelerator and other additives are used. The mixture is blended at a predetermined ratio, and then the mixture is melt-kneaded in a heating state using a kneader such as a mixing roll machine, and then cooled to room temperature, pulverized by a known means, and compressed as necessary. I do.

The method for encapsulating a semiconductor device using the thus obtained epoxy resin composition for encapsulating a semiconductor is not particularly limited, and the device can be encapsulated by a known molding method such as ordinary transfer molding. And a semiconductor device can be obtained. Post curing may be performed if necessary.

Since the triphenolmethane type resin of the present invention has an appropriate amount of a phenol novolak resin unit, it has excellent properties as an epoxy resin curing agent such as a high glass transition temperature and a low viscosity, and further has a phenol novolak polymerization unit. Of the methylene group substitution position with respect to the hydroxy group in
By setting the ratio of the o-position to a specific range, the curability is further excellent. By using this as an epoxy resin curing agent, epoxy for semiconductor encapsulation with excellent properties such as molding curability and heat resistance A resin composition is obtained.

[0047]

EXAMPLES The present invention will be specifically described below with reference to examples. The methods for measuring the physical properties of the phenolic polymer obtained in the present invention are defined in (1) to (3), and an epoxy resin composition containing a phenolic polymer as a curing agent (phenolic polymer, epoxy resin, inorganic filler) , A composition comprising a curing accelerator, a silane coupling agent, and carnauba wax)
(4) to (6) show the evaluation method, and (7) shows the moldability in the semiconductor device manufacturing process.

(1) Melt Viscosity at 150 ° C. Using an ICI melt viscometer, the melt viscosity of the phenolic polymer at 150 ° C. was measured.

(2) Degree of polymerization degree m / n The reaction rate of formaldehyde and salicylaldehyde was determined, and the methylene bond / polymerization ratio in the polymer was determined from the charged amount and the reaction rate.
The ratio of methine bonds (m / n) was determined. The formaldehyde conversion was determined by measuring formaldehyde remaining after the reaction by the hydroxylamine hydrochloride method. The reaction rate of salicylaldehydes was determined by measuring the remaining salicylaldehydes after the reaction by gas chromatography.

(3) p / o of substitution position of methylene group with respect to hydroxy group in phenol novolak resin polymerization unit
Position ratio: It was determined by the following method using ¹ H-NMR spectrum method. Chemical shifts when the positions of the hydroxy groups of both benzene nuclei bonded to the methylene group in the phenol novolak resin polymerized unit are p / p, p / o and o / o are shown in FIGS. ^{In the 1} H-NMR spectrum, p / p position: 3.76 ppm () p / o position: 3.88 ppm () o / o position: 3.96 ppm () The p / o position was determined from the integrated value of each chemical shift. The ratio was calculated by the following equation. p / o ratio = [p / p integral value + (p / o integral value /
2)] / [o / o integral value + (p / o integral value / 2)]

(4) Curatometer Curing Torque For an epoxy resin composition containing a phenolic polymer as a curing agent, the rate of increase in torque due to curing at 175 ° C. was measured with a curast meter, and the torque for 60 seconds and 90 seconds was measured. Was read.

(5) Glass transition temperature An epoxy resin composition containing a phenolic polymer as a curing agent was heated at 175 ° C. to 12 ° C. using a transfer molding machine.
After molding in 0 seconds, a test piece of an appropriate size was cut out from a molded article post-cured at 180 ° C. for 6 hours, and TMA was cut out.
The glass transition temperature was measured by the method (heating rate 5 ° C./min).

(6) Melt Viscosity The minimum melt viscosity at 175 ° C. of the epoxy resin composition containing a phenolic polymer as a curing agent was determined by a flow tester method (load: 20 kgf / cm ² , nozzle: 1 × ² L).
mm).

(7) Moldability in Semiconductor Device Manufacturing Process The semiconductor element was sealed by transformer molding, demolded at a molding time of 60 seconds, and the package hardness after air cooling 10 seconds was measured by Shore hardness. The state of the cull during molding was observed, and the presence or absence of stacking and blisters was confirmed.

Example 1 In a glass reactor equipped with a stirrer, a condenser and a nitrogen gas inlet tube, 94 g (1 mol) of phenol and a 19.5% aqueous 37% formalin solution were used.
g (0.24 mol in terms of formaldehyde) and 0.57 g of oxalic acid dihydrate were charged and reacted at 65 ° C. for 4 hours.
The ¹ H-NMR spectrum of the produced phenol novolak resin was as shown in FIG. 1, and the p / o ratio of the methylene group substitution position with respect to the hydroxy group was measured.

Thereafter, 106.2 g of phenol was further added.
(1.13 mol), 29.3 g of salicylaldehyde
(0.24 mol) and 7.1 g of 35% hydrochloric acid aqueous solution were additionally charged and reacted at 65 ° C. for 4 hours. Unreacted formaldehyde and salicylaldehyde were not detected in the condensed liquid after the reaction (reaction rate: 100%).

The condensed liquid was further heat-treated under reduced pressure to remove unreacted phenol, water, oxalic acid and HCl out of the system, thereby obtaining 99.2 g of a phenol polymer.

Raw material charge ratio: phenol is 4.4 mole times the sum of salicylaldehyde and formaldehyde. The properties of the resulting phenolic polymer are as follows,
By continuing the reaction by adding salicylaldehyde, the p / o position ratio of the methylene group substitution position to the hydroxy group in the phenol novolak resin polymerized unit becomes 1.2.
From 2.5 to 2.5. Hydroxyl equivalent: 100 g / eq 150 ° C. Melt viscosity: 190 mPa · s m / n: 1.0 (value obtained from the reaction rate of aldehydes) p / o ratio: 2.5

Example 2 In a glass reactor equipped with a stirrer, condenser and nitrogen gas inlet tube, 94 g (1 mol) of phenol and a 14.6% aqueous 37% formalin solution were used.
g (0.18 mol in terms of formaldehyde) and 1.1 g of oxalic acid dihydrate were charged and reacted at 40 ° C. for 5 hours.

After that, 17.4 g of phenol was further added.
(0.19 mol), 16.9 g of salicylaldehyde
(0.14 mol) and 8.2 g of 35% hydrochloric acid aqueous solution were additionally charged and reacted at 40 ° C. for 8 hours. Unreacted formaldehyde and salicylaldehyde were not detected in the condensed liquid after the reaction (reaction rate: 100%).

The condensed liquid was further heat-treated under reduced pressure to remove unreacted phenol, water, oxalic acid and HCl out of the system, thereby obtaining 65.0 g of a phenol polymer.

Raw material charge ratio: 3.72 moles of phenol to the sum of salicylaldehyde and formaldehyde. Properties of formed phenolic polymer Hydroxyl equivalent: 101 g / eq 150 ° C. Melt viscosity: 180 mPa · s m / n: 1.3 (value obtained from the reaction rate of aldehydes) p / o ratio: 3.0 (FIG. 2) From ¹ H-NMR spectrum)

Example 3 Instead of 8.2 g of 35% hydrochloric acid aqueous solution, 10% trifluoromethanesulfonic acid 160
The same processing as in Example 2 was performed except that mg was used.
3.0 g of a phenolic polymer was obtained.

Raw material charge ratio: 3.72 moles of phenol based on the sum of salicylaldehyde and formaldehyde. Properties of formed phenolic polymer Hydroxyl equivalent: 101 g / eq 150 ° C. Melt viscosity: 200 mPa · s m / n: 1.3 (value obtained from the reaction rate of aldehydes) p / o ratio: 2.8

Comparative Example 1 Into the glass reactors used in Examples 1 to 3, 19.5 g of a phenol 94 g (1 mol) aqueous 37% formalin solution (0.2 g in terms of formaldehyde) was added.
4 mol), and 0.34 g of oxalic acid dihydrate was charged at 90 ° C.
Allowed to react for hours. Thereafter, 106.2 g of phenol is further added.
(1.13 mol), 29.3 g of salicylaldehyde
(0.24 mol) and 7.1 g of 35% hydrochloric acid aqueous solution were additionally charged and reacted at 90 ° C. for 4 hours. After the reaction,
Unreacted formaldehyde and salicylaldehyde were not detected (reaction rate: 100%). By further heat-treating this condensed liquid under reduced pressure, by removing unreacted phenol, water, oxalic acid and HCl out of the system,
99.0 g of a phenolic polymer was obtained. Raw material charge ratio: phenol is 4.4 mole times the sum of salicylaldehyde and formaldehyde. Properties of formed phenolic polymer Hydroxyl equivalent: 100 g / eq 150 ° C. Melt viscosity: 190 mPa · sm / n: 1.0 (value obtained from the reaction rate of aldehydes) p / o ratio: 1.7

Comparative Example 2 The same treatment as in Comparative Example 1 was carried out except that the reaction temperature was 75 ° C., to obtain 99.2 g of a phenolic polymer. Properties of Produced Phenolic Polymer Hydroxyl Equivalent: 100 g / eq 150 ° C. Melt Viscosity: 190 mPa · s m / n: 1.0 (Value Obtained from Reaction Rate of Aldehydes) p / o Ratio: 1.8 (FIG. 3) From ¹ H-NMR spectrum)

[Examples 4-6, Comparative Examples 3-4]
3. Using the phenolic polymers obtained in Comparative Examples 1 and 2 as a curing agent, epoxy resin compositions were produced at the compounding ratios shown in Table 1. The compounding method is as follows:
The mixture was kneaded at ~ 90 ° C for 4 minutes, cooled and pulverized to obtain an epoxy resin composition. The properties of the curing agent and the properties of the obtained epoxy resin composition were measured. The epoxy resin used was an orthocresol type epoxy resin (Sumitomo Chemical E
SCN 195XL, epoxy equivalent 196 g / eq). Also, using the epoxy resin composition obtained here,
Low-pressure transfer molding is performed for 60 seconds at a mold temperature of 175 ° C. and a pressure of 60 kgf / cm ² to seal a semiconductor element (6.7 mm × 6.7 mm × 0.4 mm) mounted on a 42 alloy lead frame. Outer dimensions 20 × 14 × 2.7mm 60 pins-QFP
(Quat Flat Package) was manufactured. During the transfer molding, the Shore hardness of the package was measured, and the stacking and blistering of the cull portion were observed to evaluate the productivity (formability) in the actual semiconductor device manufacturing process. Table 1 shows the results.

[0068]

[Table 1]

As is evident from Table 1, the phenolic polymers obtained in Examples 1 to 3 were used as epoxy resin curing agents with low melt viscosity, rapid curability and high glass transition point of the obtained epoxy resin. It has all of. In contrast, the phenolic polymers obtained in Comparative Examples 1 and 2 have inferior curability.

[0070]

The phenolic polymer of the present invention has both polymerized units of triphenolmethane-type resin and phenol novolak resin in the molecule, and the degree of polymerization of each of them and the ratio of the degree of polymerization of both are within a specific range. And the methylene group substitution position with respect to the hydroxy group in the phenol novolak polymerized unit is 2.0 or more at the p / o position, thereby having both low melt viscosity and high glass transition temperature suitable for an epoxy curing agent. Since it is a polymer having excellent curability, it can be used as a sealing material for the latest semiconductor devices such as BGA, and is useful as an epoxy curing agent.

[Brief description of the drawings]

FIG. 1 is a ¹ H-NMR spectrum of an intermediate product (phenol novolak resin) of Example 1.

FIG. 2 is the ¹ H-NMR spectrum of the final product of Example 2.

FIG. 3 is a ¹ H-NMR spectrum of a final product of Comparative Example 2.

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Claims (10)

[Claims] 1. A phenolic polymer represented by the following general formula (1) having a melt viscosity at 150 ° C. of 50 to 50:
The methylene group substitution position with respect to the hydroxy group in the phenol novolak polymerized unit is p
A phenolic polymer having a / o position of 2.0 or more. Embedded image (In the formula, m / n is 0.7 to 1.5, R ¹ , R ² , R ³ and R ⁴ are alkyl groups, and p, q, r and s are 0 to 2.) 2. The phenolic polymer according to claim 1, wherein p, q, r and s are 0. 3. The reaction of phenols, salicylaldehydes and formaldehyde at a temperature of 70 ° C. or less in the presence of an acid catalyst at a ratio of 3.0 mol or more of phenols to 1 mol of salicylaldehydes and formaldehyde in total. The method for producing a phenolic polymer according to claim 1 or 2, wherein after the reaction is completed, phenols unreacted with the acid catalyst are removed by a reduced pressure treatment. 4. The method for producing a phenolic polymer according to claim 3, wherein the reaction is continued by additionally adding an acid catalyst during the reaction. 5. A method according to claim 1, wherein the formaldehyde is added at a temperature of not more than 70 ° C. in the presence of an acid catalyst.
A phenol novolak resin is produced by reacting with 5 mol or more of phenols, and then salicylaldehydes and, if necessary, phenols are added. 4. The method for producing a phenolic polymer according to claim 3, wherein the reaction is continued at a total amount of 2.0 mol or more of phenols per 1 mol of salicylaldehydes. 6. The method for producing a phenolic polymer according to any one of claims 3 to 5, wherein formaldehyde is used in a ratio of 0.7 to 1.5 mol per mol of salicylaldehyde. 7. The method according to claim 3, wherein the acid catalyst is hydrochloric acid, oxalic acid or trifluoromethanesulfonic acid.
The method for producing a phenolic polymer according to any one of the above. 8. A curing agent for an epoxy resin comprising the phenolic polymer according to claim 1 or 2. 9. An epoxy resin (A), according to claim 1 or 2
Phenolic polymer (B), inorganic filler (C)
And an epoxy resin composition for semiconductor encapsulation containing a curing accelerator (D). 10. A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition according to claim 9.