JP2000169537A - Liquid phenol novolac resin and curing agent,for semiconductor sealing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid phenol novolac resin which can exhibit excellent flowability, low water absorptivity, and heat resistance by bridging a skeleton component being phenol and o-substituted phenol with methylene and/or hydroxyphenylmethylene groups. SOLUTION: Formalin and at least either of o- and p-hydroxybenzaldehyde are used as a bridging agent for phenol and phenol having a 1-4C alkyl in the ortho position (e.g. o-cresol) or o-allylphenol. The compositional rate of the o-substituted phenol in the resin is 5-95 mol% based on the entire skeleton component, and that of the hydroxyphenylmethylene groups is at most 70 mol% based on the entire bridging component. The bridging agent and an at least three molar times of a phenolic compound are reacted with each other at 50-200 deg.C in the presence of an acid catalyst such as a-n acid to obtain a liquid phenol novolac resin having a number-average molecular weight of at most 400. This resin can be desirably used as a curing agent for an epoxy resin or an epoxidized phenol novolac resin for e.g. semiconductor sealing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a phenol compound having a phenol and an alkyl or allyl group having 1 to 4 carbon atoms at the ortho-position as a skeleton component of a resin, wherein the resin is crosslinked with a methylene group and / or an o-hydroxy group. The present invention relates to a liquid phenol novolak resin comprising a phenylmethylene group or a p-hydroxyphenylmethylene group. The resin is
It can be used as a binder for organic and inorganic materials and as a curing agent for epoxy resins. Particularly, a liquid phenol novolak which is suitably used as a curing agent for an epoxy resin for the electric and electronic industries, for sealing electronic components, and for a laminate material, and has excellent properties such as fluidity, low water absorption and heat resistance. Useful as a resin.

[0002]

2. Description of the Related Art Epoxy resins are widely used as resin materials for electronic materials, and various phenol novolak resins, amines and acid anhydrides are used as curing agents for the epoxy resins. In particular, a phenolic novolak resin is mainly used as a curing agent for an epoxy resin for encapsulating a semiconductor (IC) in view of heat resistance and reliability. In recent years, the integration of ICs, the miniaturization and thinning of packages, and the application of surface mounting methods have been progressing, and the sealing materials for them have been further improved in thermal shock resistance and soldering heat resistance during surface mounting work. Is required. A major factor influencing the soldering heat resistance is the water absorption of the sealing resin material. In other words, the sealing material that has absorbed water generates internal pressure due to moisture vaporization at high temperatures during surface mounting work, causing internal peeling and package cracking, resulting in poor soldering heat resistance. Therefore, phenolic novolak resins used as epoxy resin curing agents are particularly required to have low water absorption.

As a method of reducing the water absorption of the sealing material, there is a method of increasing the amount of a non-water-absorbing filler such as silica in the sealing resin material. In this case, if the viscosity of the base resin material is high, the high filling property of the filler is impaired. Therefore, it is desired that the viscosity of the phenolic novolak resin used as the curing agent is lower.

[0004] On the other hand, there is also a method in which a sealing material is made into a liquid, one-liquid type, and potting and dipping are performed at room temperature to seal semiconductors, diodes, and the like by osmotic pressure. In this case, a curing agent such as a liquid epoxy resin and a liquid acid anhydride, an amine or an amide is used, and a phenol novolak curing agent is a semi-solid or solid one or a phenol novolak resin dissolved in a solvent. I have. The sealing material using such a semi-solid or solid phenol novolak resin has poor fluidity, and the one using a solvent has a bad effect on performance because the solvent is taken into the sealing material after curing.

[0005] It has been attempted to form a solvent-free sealant by using an acid anhydride.
Hydrolysis occurs in the presence of hot water, for example, under the conditions of a pressure cooker test, and the generated acid corrodes aluminum, resulting in a decrease in the moisture resistance life. Also, amine and amide groups are not preferred in terms of reliability. In order to solve such problems, a phenol novolak resin having fluidity, low water absorption and heat resistance has been demanded.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid phenol novolak resin which solves the above-mentioned conventional problems and exhibits excellent fluidity, low water absorption and heat resistance. It was done.

[0007]

That is, the present invention relates to a phenol compound in which the resin skeleton component has an alkyl group or an allyl group having 1 to 4 carbon atoms at the ortho-position with phenol,
It is a liquid phenol novolak resin whose cross-linking is a methylene group and / or an o-hydroxyphenylmethylene group or a p-hydroxyphenylmethylene group, and is a sealing curing agent using these.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The compound used in the present invention is a phenol compound having an alkyl group or an allyl group having 1 to 4 carbon atoms at the ortho position with phenol. Examples of the phenol compound having an alkyl group having 1 to 4 carbon atoms at the ortho position include orthocresol (o-cresol) and orthoethylphenol (o
-Ethylphenol), ortho-isopropylphenol (o-isopropylphenol), 2-tert-butylphenol, o-sec-butylphenol and the like. Also, examples of the phenol compound having an allyl group at the ortho position include ortho allyl phenol (o-allyl phenol). These phenol compounds can be used alone or in combination.

In the liquid phenol novolak resin obtained in the present invention, the composition ratio of orthoalkylphenol or allylphenol as a resin skeleton component is 5 to 95 in total.
Mol%, preferably 10 to 90 mol%, more preferably 10 to 80 mol%. Even when the amount is less than 5 mol%, a liquid phenol novolak resin can be obtained, but the viscosity of the obtained resin tends to be high and tends to be semi-solid or solid. Although a liquid phenol novolak resin can be obtained with more than 95 mol%, the production cost increases.

In order to obtain these resin skeleton composition ratios, although they are somewhat affected by the synthesis conditions, it is sufficient to make the charge ratios at the time of manufacture substantially the same.

Alkyl phenols having substituents at meta- and para-positions other than ortho-position, for example, meta-cresol, para-cresol, 2,5-xylenol, meta-ethylphenol, 2,3,5-trimethylphenol, 2-tertiary When butyl paracresol, 4-tert-butylphenol, paraoctylphenol or the like is used, the fluidity is insufficient, which is not preferable.

Next, as a crosslinking agent used in the present invention,
Formaldehyde is used for the methylene group crosslinking, and examples of the aqueous formaldehyde solution include formalin (aqueous formalin solution), paraformaldehyde, and trioxane. An inexpensive formalin aqueous solution is preferable.

[0013] For the o-hydroxyphenylmethylene group or p-hydroxyphenylmethylene group, which is one of the cross-linking groups, o-hydroxybenzaldehyde or p-hydroxybenzaldehyde is used. These o-hydroxybenzaldehyde and p-hydroxybenzaldehyde may be used alone or in combination. In addition,
An o-hydroxyphenylmethylene group or a p-hydroxyphenylmethylene group converts one hydrogen of a methylene group to o
-Hydroxyphenyl group or p-hydroxyphenyl group.

In the liquid phenol novolak resin obtained in the present invention, the composition ratio of the methylene group crosslink and the o-hydroxyphenylmethylene group or the p-hydroxyphenylmethylene group crosslink is defined as the o-hydroxyphenylmethylene group or the p-hydroxyphenylmethylene group. Is 70 mol% or less, preferably 50 mol% or less, more preferably 5 to 50 mol% of the whole. If it is more than 70 mol%, the viscosity of the resulting resin is so high that it becomes semi-solid or solid at 25 ° C.

In order to obtain the composition ratio of these crosslinking groups,
The preparation ratio of formaldehyde and o-hydroxybenzaldehyde or p-hydroxybenzaldehyde during the production may be the same.

The proportion of phenol and the phenol compound to be used in the present invention, which depends on the synthesis conditions, depends on the synthesis conditions. Usually, phenol and the phenol compound are at least 3 times the mol of the compound to be cross-linked. I just need. Preferably it is 5 to 10 times mol. If the molar ratio is less than 3 times, crosslinking proceeds, and the resulting resin becomes semi-solid or solid, and loses fluidity. On the other hand, if the amount is too large, recovery of unreacted raw materials increases, which is not economical.

P-tolualdehyde, p-ethylbenzaldehyde, p-isopropenylbenzaldehyde, 3,
When a benzaldehyde having no hydroxyl group such as 4-dimethylbenzaldehyde is used, the curability and heat resistance are not sufficient.

The number average molecular weight of the liquid phenol novolak resin obtained in the present invention is not particularly limited,
Any substance that exhibits a liquid state at 5 ° C. may be used, but a value calculated in terms of polystyrene is preferably 400 or less.

The liquid phenol novolak resin obtained in the present invention exhibits a liquid state at 25 ° C. and has a viscosity of 500 poise or less at 25 ° C., preferably 40 poise.
The resin is preferably 0 poise or less, more preferably 350 poise or less.

The general formula (1) of the liquid phenol novolak resin obtained in the present invention is shown.

[0021]

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The liquid phenol novolak resin of the present invention is synthesized, for example, as follows. That is, the above-mentioned phenol compound, cross-linking agent, and synthesis catalyst are charged into a reactor at a predetermined blending ratio, reacted at a predetermined temperature and a predetermined reaction rate, and then subjected to a step of removing unreacted components. Get.

At this time, an acid is used as the synthesis catalyst, and organic acids such as oxalic acid, paratoluenesulfonic acid, and dimethyl sulfuric acid, and inorganic acids such as hydrochloric acid and sulfuric acid can be used. The amount of the catalyst used is 0.01% by weight based on the phenol compound.
It is selected and used in the range of １1% by weight. If the amount is too small, the reaction speed is slow. If the amount is too large, there is a problem that the reaction proceeds rapidly and the reaction cannot be controlled.

The reaction temperature depends on the compounding ratio of the compound used, but is usually from 50 ° C. to 200 ° C., preferably from 70 ° C.
The temperature is 180 ° C, more preferably 80 ° C to 180 ° C. If the temperature is too low, the polymerization does not proceed. If the temperature is too high, the control of the reaction becomes difficult, and it becomes difficult to obtain the desired liquid phenol novolak resin.

The reaction time depends on the reaction temperature, but is usually within 10 hours.

The reaction pressure is usually carried out under normal pressure, but it can also be carried out under slightly elevated or reduced pressure.

After the reaction, the unreacted phenol compound and the like are usually removed under reduced pressure to obtain the desired liquid phenol novolak resin.

Next, a curing agent is described as an application of the phenol novolak resin as an epoxy resin. Since this liquid phenol novolak resin has a phenolic hydroxyl group, it can be used as a curing agent for an epoxy resin in the same manner as a normal phenol novolak resin. A cured product of an epoxy resin using this phenol novolak resin as a curing agent is excellent in low water absorption and heat resistance.

As the epoxy resin used in this case,
For example, bisphenol diglycidyl ether type epoxy resin in which an epoxy group is added to bisphenols such as bisphenol A and bisphenol F; Novolak type epoxy resin having an epoxy group; glycidylamine type epoxy resin such as diphenylmethanediaminetetraglycidyl ether and cyclohexanediaminetetraglycidylether; aliphatic epoxy resin such as epoxidized SBR and epoxidized soybean oil; 4,4′-dihydroxy Biphenyl and 3,3 ', 5
Dihydroxybiphenyl diglycidyl ether type epoxy resin having an epoxy group added to dihydroxybiphenyls such as 5′-tetramethyl-4,4′-dihydroxybiphenyl; polycyclic aromatic epoxy such as 1,6-dihydroxynaphthalenediglycidyl ether Novolak type epoxy resin, dihydroxybiphenyl diglycidyl ether type epoxy resin and polycyclic aromatic type epoxy resin are preferable, and novolak type epoxy resin is more preferable.

In order to obtain a cured epoxy resin using the liquid phenol novolak resin of the present invention as a curing agent, for example, the hydroxyl group of the phenol novolak resin of the present invention may be prepared according to the method described in JP-A-8-143648. In order for the ratio with the epoxy group of the epoxy resin to be approximately equivalent,
The phenol novolak resin of the present invention was mixed with the above-mentioned epoxy resin to form an epoxy resin composition,
Heat at about 250 ° C. At this time, it is preferable that a curing accelerator generally used for accelerating the curing, for example, N-methylimidazole, triethylamine, triphenylphosphine, or the like is added to the epoxy resin composition. If necessary, various additives such as a filler, a coupling agent, a flame retardant, a lubricant, a release agent, a plasticizer, a colorant, and a thickener may be added.

Next, the use of the liquid phenol novolak resin of the present invention as a raw material for an epoxy resin will be described. The liquid phenol novolak resin of the present invention can be epoxidized into an epoxidized novolak resin.
This epoxidized novolak resin is disclosed in, for example, JP-A-8-1
According to the method described in JP-A-43648, the liquid phenol novolak resin of the present invention is obtained by reacting with the epihalohydrin such as epichlorohydrin in the presence of an alkali. The epoxidized novolak resin of the present invention can be cured using various epoxy resin curing agents. The obtained cured epoxy resin is excellent in low water absorption and heat resistance similarly to the above epoxy resin.

Examples of the curing agent for the epoxy resin in this case include various amines, polycarboxylic acids and their anhydrides, phenol novolak resins (including the phenol novolak resins of the present invention), urea resins, melamine resins and the like. Can be ordinary phenolic novolak resin,
Phenol novolak resins (including the phenol novolak resin of the present invention) such as orthocresol novolak resins and brominated phenol novolak resins are preferred.

In order to obtain a cured product of the epoxidized novolak resin of the present invention, an epoxy resin composition can be obtained in the same manner as in the above-mentioned curing method, and thereafter, the composition can be heated. The same applies to the point that a curing accelerator and other additives can be added. As described above, a resin obtained by using the phenol novolak resin of the present invention as a curing agent for an epoxy resin exhibits excellent properties in heat resistance, adhesion, water absorption, and mechanical properties.

Further, the epoxidized novolak resin obtained in the present invention is excellent even if a pigment such as carbon black, a filler such as asbestos, silica, talc, and a reinforcing material such as glass fiber, rock wool and cotton cloth are added. A resin having the above properties is obtained.

As described above, the liquid phenol novolak resin obtained in the present invention can be used as a binder for organic and inorganic materials and a curing agent for epoxy resin. Its use is suitable for use as an epoxy resin curing agent for the electrical and electronic industries, for sealing electronic components, and for laminate materials,
It is mainly suitable for semiconductor encapsulants, especially for semiconductor encapsulants for chip size packages.

As methods for sealing electronic components such as semiconductors using these resins, transfer molding, compression molding, injection molding and the like are used. In particular, when the resin composition is in a liquid state, a casting method,
Known molding methods such as a dipping method and a dropping method can be used.

[0037]

The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Example 1 940 g (10 mol) of phenol, o-cresol 10
80 g (10 mol), 324 g (4 mol) of 37% formalin and 20 g of oxalic acid were placed in a three-necked flask, and 100 ° C.
For 5 hours, and then heated to 160 ° C. for dehydration. Subsequently, unreacted components were removed at 160 ° C. under a reduced pressure of 40 torr to obtain 730 g of a liquid phenol novolak resin. The viscosity of the obtained resin was 300 poise at 25 ° C. Next, 55 parts by weight of the obtained resin and screw A
100 parts by weight of an epoxy resin (manufactured by Yushi Shell Epoxy Co., Ltd .; Epicoat 828) and 1 part by weight of triphenylphosphine are uniformly mixed at 25 ° C., gelled at 150 ° C. for 10 minutes, and then molded (150 × 70 × 4 mm). ), And cured in a thermostat at this temperature for 5 hours and further at 180 ° C. for 5 hours to prepare a test piece. Table 3 shows the curing characteristics of the test pieces thus obtained. The methods for evaluating the properties of the obtained liquid phenol novolak resin and the curing properties of the test piece are as follows. (1) Number average molecular weight The molecular weight distribution was measured using a GPC measuring device (HLC-802A, manufactured by Tosoh Corporation), and the number average molecular weight was calculated in terms of polystyrene. (2) Viscosity measurement It was measured with a B-type viscometer according to JIS K6909. (3) Measurement of OH equivalent A 2-3 g sample was acetylated with 1.25 g of acetic anhydride, and the acetic acid after acetylation was titrated with potassium hydroxide to determine the OH equivalent. (Acetylation method) (4) Water absorption According to JIS K6911, a test piece (50 ± 1 m in diameter)
m, thickness 3 ± 0.2 mm), immersed in hot water at 100 ° C. for 24 hours, and calculated from the weight increase before and after. (5) Measurement of Tg (glass transition temperature). It was measured by the TMA method. (6) Flexural strength and Young's modulus Measured according to JIS K6911.

Examples 2 to 10 Liquid phenol novolak resins were synthesized in the same manner as in Example 1 except that the reaction components and the amounts used were as shown in Table 1, and the amounts of the obtained resins were as shown in Table 3. A test piece was created at. Tables 3 and 5 show the physical properties of the obtained resin and the cured product properties of the test piece, respectively.

Comparative Examples 1 to 6 A liquid phenol novolak resin was synthesized in the same manner as in Example 1 except that the reaction components and the amounts used were changed as shown in Table 2, and the amount of the obtained resin was adjusted as shown in Table 4. A test piece was created at. The physical properties of the obtained resin and the cured product characteristics of the test piece are shown in Tables 4 and 6, respectively.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

[0044]

[Table 4]

[0045]

[Table 5]

[0046]

[Table 6]

[0047]

As described in detail above, the liquid phenol novolak resin of the present invention provides a resin cured product exhibiting excellent fluidity, low water absorption properties and heat resistance as a curing agent such as an epoxy resin. The obtained resin can be applied to a liquid encapsulant, and can be used as an encapsulant, especially for a semiconductor encapsulant, due to the above properties.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Kumi Mitsumoto 1988, Ogushi, Obe-shi, Ube-shi, Yamaguchi 20 Meiwa Kasei Co., Ltd. F term (reference) 4J033 CA01 CA02 CA03 CA05 CA10 CA11 CA12 CA29 CB01 HA02 HA12 HB06 4J036 AA01 AC01 AD01 AF01 AF07 AF10 AF15 AH06 AH07 AJ08 AK01 AK02 DC05 DC41 DD07 FB08 JA07 4M109 EA03 EB03 EB06 EB07 EB08 EB09 EB19 EC01 EC05 EC09

Claims (7)

[Claims] 1. A resin skeleton component comprising phenol and a phenol compound having an alkyl group or an allyl group having 1 to 4 carbon atoms at an ortho position, wherein a crosslinking group is a methylene group and / or o
-A liquid phenol novolak resin comprising a hydroxyphenylmethylene group or a p-hydroxyphenylmethylene group. 2. The liquid phenol novolak resin according to claim 1, wherein the composition ratio of the phenol compound having an alkyl group or an allyl group having 1 to 4 carbon atoms at the ortho position in the resin skeleton component is 5 to 95 mol% of the whole. . 3. The liquid phenol novolak resin according to claim 1, wherein the composition ratio of the o-hydroxyphenylmethylene group or the p-hydroxyphenylmethylene group in the crosslinking group is 70 mol% or less. 4. The composition according to claim 1, wherein the number average molecular weight is 400 or less.
The liquid phenol novolak resin according to any one of claims 3 to 3. 5. A hardening agent for sealing containing the liquid phenol novolak resin according to claim 1. 6. The encapsulating hardener for semiconductors according to claim 5, wherein the encapsulating hardener is a semiconductor encapsulating hardener. 7. An epoxy resin obtained from the liquid phenol novolak resin according to claim 1.