JPH04100820A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin composition which is stable and sufficiently storable at ordinary temperature and can be cured rapidly when molded by heating by mixing an epoxy resin with a phenolic curing agent, an inorganic filler and a specified cure accelerator. CONSTITUTION:An epoxy resin composition is obtained by mixing an epoxy resin with a phenolic curing agent (e.g. novolac phenolic resin or resol phenolic resin), an inorganic filler (e.g. crystalline silica or talc) and a cure accelerator of the formula [wherein R<1>, R<2> and R<3> are each a (substituted) monovalent hydrocarbon group] as essential components. This composition is excellent in storage stability and can be cured rapidly when molded by heating to give a cured product of good electric and chemical properties, and a semiconductor device sealed with this cured product is excellent in humidity resistance and has high reliability.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides an epoxy resin composition that has good storage stability and that quickly cures during heat molding to give a cured product with excellent moisture resistance. The present invention relates to a semiconductor device sealed with a cured product of the epoxy resin composition.

[Conventional technology]

As a package for semiconductor devices, plastic has good electrical properties, mechanical properties, and chemical resistance.

Epoxy resins that provide cured products with moisture resistance and the like are widely used. Among these, a resin composition in which a phenolic resin is blended as a curing agent with a novolac type epoxy resin, and an inorganic filler is further added thereto is currently the mainstream for resin encapsulation of semiconductor devices.

Such epoxy resin compositions generally use a catalyst (curing accelerator) to accelerate the curing of the resin during molding, and nitrogen-containing, phosphorus-containing compounds, etc. are used as the curing accelerator. .

[The invention attempts to solve the problem. I! Title]

However, depending on the type of curing accelerator that is commonly used, it exhibits catalytic action even at relatively low temperatures, so curing may occur gradually during heating and mixing of the epoxy resin with the curing agent and other components or during subsequent storage. As the process progresses, moldability may deteriorate, such as a decrease in fluidity and an increase in viscosity during molding, and variations in hardenability can cause a drop in the electromechanical and chemical properties of the molded product. However, there is a problem in that the temperature must be strictly controlled during mixing and storage of the epoxy resin composition. Therefore, it is desired to develop an epoxy resin composition that is stable at room temperature, has good storage stability, and quickly cures during heat molding.

The present invention has been made in view of the above circumstances, and provides an epoxy resin composition that has good storage stability, cures rapidly during heat molding, and provides a cured product with excellent properties especially for semiconductor encapsulation. Another object of the present invention is to provide a highly reliable semiconductor device sealed with a cured product of the epoxy resin composition.

[Means and effects for solving the problem] As a result of intensive studies to achieve the above object, the present inventors found that (A) an epoxy resin, (B) a phenolic curing agent, and (C) an inorganic filler. Further, (D) a curing accelerator is added to the epoxy resin composition containing the following general formula (1) (wherein R', R2 and R3 are the same or different substituted or unsubstituted monovalent hydrocarbon groups, respectively). ), the resulting epoxy resin composition shows little change in curability, etc. even after long-term storage.
In addition to having good storage stability, it cures quickly during heat molding, and the cured product has good electrochemical properties, and semiconductor devices sealed with the cured product have excellent moisture resistance. , it was found that it has excellent reliability.
This is what led to the present invention.

Therefore, the present invention includes the above-mentioned (A) component and (B) component.

Provided are an epoxy resin composition characterized by containing component (C) and component (D) as essential components, and a semiconductor device sealed with a cured product of the epoxy resin composition.

The present invention will be explained in more detail below.

As described above, the epoxy resin composition of the present invention comprises (A)
It contains an epoxy resin, (B) a phenolic curing agent, (C) an inorganic filler, and (D) a curing accelerator as essential components.

Here, the epoxy resin as component (A) is as follows.

There is no particular restriction as long as it has one or more Niei oxy groups in one molecule, such as bisphenol type epoxy resin, alicyclic epoxy resin, phenol novolac type epoxy resin, bresol novolac type epoxy resin, triphenol. Alkane-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, halogenated epoxy resins, and the like are preferably used, and one type thereof can be used alone or two or more types can be used in combination.

In addition, from the viewpoint of moisture resistance of the composition, the above-mentioned epoxy resin has a hydrolyzable chlorine content of 500 ppm or less, free Na,
(:, It is desirable to use one in which the Q ions are each 2 ppm or less and the organic acid content is looppm or less.

Next, as the phenolic curing agent of the component (B), for example, phenolic resins such as novolac type phenolic resin, resol type phenolic hard resin, tripynol alkane type resin, naphthol type resin, biphenyl type phenolic resin, etc. It is possible to use one type of these two types alone or in combination of two or more types. The phenolic resin used as a curing agent contains 2 ppm or less of free Ha and CQ ions each, 1% or less of phenol, and is resistant to the Cannizzaro reaction of trace amounts of formaldehyde remaining during manufacturing. The resulting organic acids such as formic acid are 110
It is desirable that the content of free Na, CQ ions, and organic acids in the phenol resin is higher than the above amount, as the moisture resistance of the encapsulated semiconductor device may deteriorate. If the amount of phenol in the monomer is more than 1%, defects such as voids, unfilling, and sink marks may occur in the molded product. Furthermore, the softening point of Funinol novolac resin is preferably 50 to 120°C, and 50 to 120°C.
If the temperature is less than 0°C, the secondary transition point of the cured product may become low and the heat resistance may deteriorate; if it exceeds 120°C, the melt viscosity of the composition may become too high, resulting in poor workability.

In addition, in the epoxy resin composition of the present invention, (A)
The curing agent for the component epoxy resin is mainly composed of the phenolic curing agent component (B), and diaminodiphenylmethane may be used as needed.

An amine curing agent typified by metaphenylenediamine and an acid anhydride curing agent such as pyromellitic anhydride and benzophenonetetracarboxylic anhydride may be used in combination.

Here, the blending amount of the curing agent is not particularly limited, but the molar ratio of the epoxy group of the epoxy resin to the phenolic hydroxyl group of the curing agent is 0.8 to 2. In particular, it is preferable to set the value in the range of 1 to 1.5. If the molar ratio of both groups is less than 0.8, the curing characteristics of the composition and the secondary transition temperature of the molded product may become low, resulting in a decrease in heat resistance. Electrical characteristics may deteriorate.

Inorganic fillers for component (C) include fused silica and crystalline silica, as well as silicon nitride, alumina, aluminum nitride, boron nitride, magnesium oxide, calcium carbonate, calcium carbonate, zirconium, talc, clay, mica, and glass fiber powder. etc. are not used.

As such an inorganic filler, amorphous, sintered, spherical, etc. can be used, but as the sealing material, a spherical or nearly spherical filler is particularly preferable. Particularly in the case of alumina, when particles are observed in scanning electron micrographs, the axial ratio of the major axis to the minor axis of the particles is 1 to 2. Especially 1-1
．． It is preferable that the axial ratio is 7. If alumina having an axial ratio of more than 2 is used, the fluidity of the composition may deteriorate.

The average particle size of the inorganic filler is preferably 5 to 50 microns, but one having an average particle size of 0.1 to 5 microns may be used as long as it does not exceed 30% of the total filler amount. Although the amount of the inorganic filler contained in the W fat is not particularly limited, it is preferably 60% by weight or more of the entire resin composition.

In addition, the inorganic filler may be treated in advance with a silane coupling agent, etc. 5 In this case, the silane coupling agent used for the treatment is as expressed by the following structural formula (4) % formula % (4) Silanes containing hydrolyzable residues are preferably used.

In the above formula, R5 is a hydrogen atom or a methyl group.

Non-functional alkyl, alkenyl, aryl groups such as ethyl, propyl, phenyl, as well as epoxy, amino, acrylic, alkenyl, acyl functionalities as shown below - CM2CHCH20CH2CH, CH, -~1 H, NCH2CH, NHCH2CH2CH2-R"R'
NCE-f2CH2CH2- R', R""F(+CdHzd+1.C,H9C
H2d=1-6 integer CH2=C(R')COO(CH
,) n-R'=H, CH, n=1 Integer of 3 CH2=CH(CHz)-m=Integer of O~4 HOCO(
Hz) Q Q=2~18 (1) M number, while R5
Examples include alkyl groups, alkenyl groups, aryl groups, and carbonyl groups.

Among them, methyl group, ethyl group, isopropenyl group, etc. are common, and C is 1 to 4.

More preferably, C is 3 or 4.

Either dry or wet methods can be used to treat the inorganic filler with a silane coupling agent.The dry method uses a ball mill, Henschel mixer, etc., and the wet method involves adding the silane coupling agent to the inorganic filler in a solvent. mix,
This can be done by stirring. The amount of the silane coupling agent is 0.001 to 8 parts, more preferably 0.001 to 8 parts per 100 parts (by weight, the same applies hereinafter) of the inorganic filler.
．． The range is 01 to 5 parts. If the amount of the silane coupling agent is too small, the effect of the treatment, ie, improvement in moisture resistance, etc., may not be achieved, and if the amount is too large, the properties such as dryness may worsen. These silane coupling agents may be used in combination of two or more types, and furthermore, they may be partially hydrolyzed and used.Solvents used in the wet method include toluene, xylene, etc. hydrocarbons, alcohols such as methanol, ethanol, and isopropyl alcohol, ketones such as acetone and 2-butanone, and isopropyl ether.

Examples include ethers such as tetrahydrofuran, and water and a tin-, titanium-, or amine compound as a hydrolysis accelerator can also be used in combination. After being treated in this way, it can also be sintered in a heating furnace at about 400 to 1200°C.

The curing accelerator used as component (D) in the epoxy resin of the present invention is represented by the following formula (1) (wherein R', R2 and R3 are the same or different substituted or unsubstituted monovalent hydrocarbon groups, respectively). ).

Here, the substituted or unsubstituted monovalent hydrocarbon group represented by an, R2, R3 is preferably one having 1 to 10 carbon atoms, especially one having 1 to 8 carbon atoms. For example, a methyl group, an ethyl group,
Alkyl groups such as propyl groups and butyl groups, or chloromethyl groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms, etc., 3,3,3-trifluoropropyl groups, phenyl groups, tolyl groups, etc. aryl group, benzyl group.

Aralkyl groups such as phenethyl groups can be mentioned, but in particular R1 is a methyl group, butyl group, phenyl group, R2
and R1 is most commonly a methyl group.

The compound of formula (1) above is a known substance obtained by reacting the corresponding tertiary phosphine with the corresponding phosphoric acid ester, for example, by reacting triphenylphosphine, tributylphosphine, etc. with dimethylmethanephosphonate, etc. obtained by. Specifically, the formula (1
) Compounds include methyltriphenylphosphonium methylmethanephosphonate, methyltributylphosphonium methylmethanephosphonate, benzyltriphenylphosphonium benzylmethanephosphonate, etc.
One type of these can be used alone or two or more types can be used in combination.

In addition to the curing accelerator represented by formula (1), other curing accelerators can be used in the epoxy resin of the present invention; in this case, in particular, 1,8-diazabicyclo(5,
4,0) Combination with Undecene-7 is desirable from the viewpoint of curability, moisture resistance, etc. The total amount of the curing accelerator is 0.1 to 1 part per 100 parts of the total amount of epoxy resin and curing agent. parts, particularly preferably in the range of 0.3 to 7 parts.

The curing accelerator represented by formula (1) is 10 to 10 out of all the curing accelerators.
The content is preferably 100% by weight, particularly 20 to 100% by weight.

The epoxy resin composition of the present invention has even lower S! expansion rate,
Low modulus, giving good moisture resistance.

It is desirable to blend a silicone-modified epoxy resin and/or a silicone-modified phenol resin.

This silicone-modified diboxy resin and phenolic resin have the following formula (2) % formula % (2) in the alkenyl group of the alkenyl group-containing dipoxy resin or the alkenyl group-containing phenol resin (in the formula, R9 is Similar to R1-R3, it represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and a and b are 0.01≦a<1°1≦b<3.1≦a
It is a positive number that satisfies + b < 4. Further, the number of silicon atoms in one molecule is an integer of 20 to 400, and the number of hydrogen atoms directly bonded to silicon atoms in one molecule is an integer of 1 or more. ) is an organosilicon compound represented by SiH
Polymers to which groups are added can be suitably used.

In this case, the alkenyl group-containing epoxy resin or phenol resin is represented by the following formula (3) (wherein R'' is ○CH, CH-CH2, or a wood group).

RIL is a methyl group or a hydrogen atom, and p+'T is 0≦
It is an integer represented by p≦10, 1≦9≦3. ) Alkenyl group-containing epoxy resins or phenol resins shown in the following formulas can be suitably used.

In this case, the silicone-modified epoxy resin or phenol resin has a hydrolyzable chlorine content of 500 ppm or less, free Na and CM ions of 2 ppm or less each,
The organic content is preferably 1100 pp or less, and if the content of hydrolyzable chlorine, free NagCQ ions, and organic compounds exceeds the above value, the heat resistance of the sealed semiconductor device may deteriorate. be.

The silicone-modified epoxy resin or phenol resin may be used alone or in combination of two or more types, and the amount to be blended is 100% in total of the epoxy resin and curing agent.
The amount is preferably 5 to 50 parts. If the amount of the silicone-modified epoxy resin is less than 5 parts, sufficient low stress properties may not be obtained, and if it exceeds 50 parts, the mechanical strength of the molded product may decrease.

The composition of the present invention may further contain various additives as necessary, such as waxes such as carnauba wax, mold release agents such as fatty acids such as stearic acid, and metal salts thereof (especially adhesive , carnauba wax is suitably used in terms of mold release properties), pigments such as carbon black, cobalt blue, red iron oxide, flame retardants such as antimony oxide, halogen compounds, anti-aging agents, silane coupling agents, ion exchange Substances and the like can also be used as appropriate.

Note that the epoxy resin composition of the present invention is produced by uniformly stirring and mixing predetermined amounts of the above-mentioned components, heating the mixture to a temperature of 60 to 95°C, and using a kneader, roll,
It can be obtained by kneading, cooling, and pulverizing using an extruder or the like.

The epoxy resin composition of the present invention can be effectively used for resin sealing of semiconductors such as ICs, LSIs, transistors, thyristors, diodes, etc., and for manufacturing printed circuit boards. When performing resin sealing, conventionally employed molding methods such as transfer molding, injection molding, and casting can be used. Molding conditions are temperature 150
~180℃, Bost cure 150~180'C"p2
It is preferable to carry out the treatment for about 16 hours.

〔Effect of the invention〕

As explained above, the epoxy resin composition of the present invention is
It has excellent storage stability and cures rapidly during heat molding to give a cured product with good electrochemical properties. Therefore, it can be sealed with a cured product of the epoxy resin composition of the present invention. The resulting semiconductor device has excellent moisture resistance and is highly reliable.

EXAMPLES Hereinafter, the present invention will be specifically explained by showing examples and comparative examples, but the present invention is not limited to the following examples. In addition, in the following examples, all parts are parts by weight.

[Example 1] 500 parts of crystalline silica (average particle size L7-) was placed in a Henschel mixer, and 2.0 parts of γ-glycidoxypropyl containing 0.02% by weight of 1.8-diazapine claw 7-lanthicene was added. Trimethoxysilane was sprayed and evenly dispersed. after that.

Heat treatment was performed at 180°C for 12 hours.

20 parts of silicone-modified epoxy resin (the subscript in the formula is an average value, epoxy equivalent: 295), which is an addition reaction product with this inorganic filler, and a cresol novolac type epoxy resin (epoxy equivalent: 230
) 13 parts, a naphthol type epoxy resin with a boxy equivalent of 21
5) 30 parts, poxy equivalent to brominated epoxy resin 280)
5 parts, phenol novolac resin (phenol equivalent weight 11
0) 32 parts, carnauba wax 1.2 parts, γ-glycitoxypropyltrimethoxysilane 1.8 parts, carbon black 2 parts, methyltriphenylphosphonium methylmethanephosphonate 0.95 parts and 1,8-diazabicyclo-7 - 0.18 part of undecene was kneaded using a heated roll at 80 to 90°C, cooled and pulverized to obtain a niboxy resin.

[Example 2] An epoxy resin composition was prepared in the same manner as in Example 1, except that 95 parts of methyltriphenylphosphonium methylmethanephosphonate in Example 1 was replaced with 0.80 parts of methyltributylphosphonium methylmethanephosphonate. Obtained.

[Example 3] 0.74 parts of methyltriphenylphosphonium methylmethanephosphonate and 0.18 parts of 1,8-diazabicyclo-7-undecene in Example 1 were replaced with 2.48 parts of methyltriphenylphosphonium methylmethanephosphonate. An epoxy resin composition was obtained using the same formulation as in Example 1 except for this.

[Example 4] An epoxy resin composition was obtained in the same manner as in Example 1, except that the inorganic filler in Example 1 was replaced with 370 parts of fused silica (average particle size: 22 mm).

[Example 5] The inorganic filler in Example 1 was replaced with 550 parts of α-alumina (average particle size 25#) and 110 parts of fused silica (average particle size 1.2x) treated in the same manner as in Example 1. An epoxy resin composition was obtained using the same formulation as in Example 1.

[Example 6] Example except that the inorganic filler in Example 1 was replaced with 500 parts of spherical alumina (average particle size 15 tm) treated in the same manner as in Example 1 and IQO parts of fused silica (average particle size 25-). An epoxy resin composition was obtained using the same formulation as in Example 1.

[Comparative Example 1] 2.48 parts of the compound methyltributylphosphonium methylmethanephosphonate in Example 3 was dissolved in 2-ethyl-4
- An epoxy resin composition was obtained in the same manner as in Example 1 except that 0.64 part of methylimidazole was used.

[Comparative Example 2] 0.95 parts of the compound methyltriphenylphosphonium methylmethanephosphonate in Example 1 was added to Tris(4-
An epoxy resin composition was obtained in the same manner as in Example 1 except that 0.60 part of methoxyphenyl)phosphine was used.

[Comparative Example 3] Epoxy resin with the same formulation as in Example 1 except that 0.95 parts of the compound methyltriphenylphosphonium methylmethanephosphonate in Example 1 was replaced with 1-1.15 parts of triphenylphosphine triphenylbore. A composition was obtained.

[Comparative Example 4] 0.95 parts of the compounds methyltriphninylbosphonium methylmethanephosphonitrate and 0.18 parts of 1,8-diazabicyclo-7-undecene in Example 6 were replaced with 0.66 parts of 2-phenylimidazole. An epoxy resin composition was obtained in the same manner as in Example 6 except for the following.

Regarding these compositions, curability during molding and storage stability 1
Bending strength, thermal shock resistance test, and moisture resistance of the power IC (aluminum corrosion test 9I) were evaluated by the following methods. The results are shown in Table 1.

Using a mold that complies with spiral flow EMMI standards, 175"C, 7
Immediately after blending and after 90 days of storage at 10°C, it was determined under the conditions of 0 kg/J.

Using a Natsumi transfer molding machine, 175℃/70-・■-
The hardness at the time of heating after molding for 2 minutes with 2 was measured using a Barcol hardness meter of 93.
5 was used for measurement.

An epoxy resin composition was molded into a 14-bin IC designed to study the corrosion of aluminum metal electrodes with an aluminum wire element ratio using a transfer molding method, and a bias voltage of 15 V was applied in a high-pressure cooker at 125°C and 85% humidity. I put it in for 250 hours and checked the open defect rate of the wiring.

From the results shown in Table 1, the epoxy l! I fat composition (example) is
Compared to the epoxy resin composition (comparative example) that does not contain this curing accelerator, the curability is good and the storage stability is good. Also.

It is recognized that the epoxy resin composition of the present invention provides a cured product with an excellent semiconductor protection function, and an IC sealed with such a cured product has excellent moisture resistance.

Applicant: Shin-Etsu Chemical Co., Ltd. Agent: Patent Attorney Takashi Kojima

Claims (1)

[Claims] 1. (A) Epoxy resin, (B) Phenolic curing agent, (C) Inorganic filler, (D) General formula (1) below ▲There are mathematical formulas, chemical formulas, tables, etc.▼…( 1) (However, in the formula, R^1, R^2, and R^3 are the same or different substituted or unsubstituted monovalent hydrocarbon groups, respectively.) A curing accelerator represented by the following is blended as an essential component. An epoxy resin composition characterized by: 2. A semiconductor device sealed with a cured product of the epoxy resin composition according to claim 1.