JPH10251383A - Hardening promoter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hardening promoter for an epoxy resin capable of imparting excellent fluidity, hardenability, preservation stability after hardening and crack resistance when soldering to a resin composition and useful for sealing of soldered material by mixing a phenolic resin with a specific phosphorus- containing boron compound. SOLUTION: This hardening promoter is obtained by homogeneously mixing (A) a phenolic resin e.g. the one containing <=70wt.% resin of the formula [R<1> is a divalent aromatic group having no OH; R<2> is a divalent aromatic group having OH; R<3> is a monovalent aromatic group having OH; (n) is >=0]}, (B) a tetrasubstituted phosphonium tetrasubstituted borate such as tetraphenylphosphonium tetraphenylborate. Preferably, the hardening promoter comprises 3-30 pts.wt. component B based on 100 pts.wt. component A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curing accelerator for epoxy resin, an epoxy resin composition, a semiconductor device, and a method for producing the same.

[0002]

2. Description of the Related Art Epoxy resins are excellent in heat resistance, moisture resistance, electrical properties, adhesiveness, etc., and can be imparted with various properties by blending and prescription, so that they are used as industrial materials such as paints, adhesives, and electrical insulating materials. Have been.

For example, as a method for sealing electronic circuit components such as semiconductor devices, a hermetic seal made of metal or ceramic and a phenol resin, silicone resin,
Resin sealing using an epoxy resin or the like has been proposed. Among them, resin sealing with an epoxy resin is most actively performed in terms of balance between economy, productivity and physical properties.

On the other hand, in recent years, the density and automation of mounting a semiconductor device package on a printed circuit board have been advanced, and instead of the conventional “insert mounting method” in which lead pins are inserted into holes of the board, the package is mounted on the surface of the board. "Surface mounting method" for soldering has become popular.

[0005] Along with this, the package is also a conventional DIP
(Dual in-line package) to thin FPP (flat plastic package) suitable for high-density mounting and surface mounting.

Although the degree of integration of IC chips has been improved due to advances in microfabrication technology, the area occupied by IC chips in a package has been increased in order to further increase the number of integrated circuits. It is becoming pinned.

In order to seal these packages, if the fluidity of the sealing resin is not maintained at a high level, the packages will not be filled or voids will occur, resulting in defective production. In these respects, fluidity and storage stability will become increasingly important in the future.

[0008] In recent years, a semiconductor device is encapsulated by using a tablet-shaped epoxy resin composition, pouring the epoxy resin composition into a mold heated to 150 ° C. or higher using a low-pressure transfer molding machine, and curing the epoxy resin composition. It is done in. Since molding is usually performed in a short time of 180 seconds or less, curability is also an important physical property. If the curability is poor, problems such as mold stains are likely to occur.

In surface mounting, mounting is usually performed by solder reflow. In this method, the package is exposed to a high temperature of 200 ° C. or more to melt the solder and bond the chip and the frame. At this time, if the water absorption of the resin is high,
A phenomenon occurs in which the package is cracked due to rapid expansion of moisture in the package. Therefore, crack resistance during solder reflow is very important.

Conventionally, as a curing agent for curing the epoxy sealing resin composition, an amine-based, acid anhydride-based, phenol-based curing agent has been used. Usually, the curing reaction is difficult to proceed only with the curing agent, and therefore, a curing accelerator is added. As the curing accelerator, tertiary amine compounds, secondary amine compounds, boron fluoride, piperidine,
Imidazoles, tertiary phosphine compounds and the like have been used. An epoxy sealing resin composition is obtained by blending an epoxy resin, an inorganic filler, and the like in addition to these curing agents and curing accelerators.

However, according to the conventional compounding method, it is necessary to obtain an epoxy sealing resin composition which can obtain a cured product which simultaneously satisfies characteristics such as fluidity, curability, crack resistance during solder reflow, and storage stability. Could not.

On the other hand, JP-B-51-24399 describes that an epoxy sealing resin composition having excellent curability and storage stability can be obtained by combining an epoxy resin, a phenol novolak resin curing agent and a tetra-substituted borate. Have been. JP-B-56-45491 describes a system in which a phenol novolak resin is used as a curing agent, tetraphenylphosphonium / tetraphenyl borate is used as a curing accelerator, and a cresol novolak epoxy resin, an alicyclic epoxy resin is used as an epoxy resin. Have been. However, these epoxy sealing resin compositions have a problem that crack resistance during solder reflow is not sufficient.

By the way, tetraphenylphosphonium tetraphenylborate is extremely stable around room temperature.
As a potential catalyst that demonstrates its ability as a catalyst at high temperatures,
Attention has been paid. Use of this compound can be expected to improve the fluidity of the epoxy sealing resin composition. However, at present, a sufficient effect as a curing accelerator cannot be obtained simply by adding and mixing tetraphenylphosphonium / tetraphenylborate.

[0014]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a cured material which is suitable for semiconductor encapsulation, has excellent fluidity and curability during molding, and has excellent crack resistance and storage stability during solder reflow. It is an object of the present invention to provide an epoxy resin composition which gives a product and a curing accelerator for an epoxy resin which can influence the warp.

[0015]

SUMMARY OF THE INVENTION The present invention has been achieved as a result of studying to solve the above-mentioned problems in the prior art. That is, the present invention provides: 1. An epoxy resin curing accelerator in which the phenolic resin (A) and the tetra-substituted phosphonium / tetra-substituted borate (B) are substantially uniformly mixed. "For 100 parts by weight of the phenolic resin (A),
The epoxy resin curing accelerator described above, wherein the content of the tetra-substituted phosphonium / tetra-substituted borate (B) is in the range of 3 to 30 parts by weight. "3. "The epoxy resin curing accelerator according to any one of the above, wherein the phenolic resin (A) contains 70% by weight or more of the phenolic resin (A1) represented by the chemical formula (I).

Embedded image R ³ — (— CH ₂ —R ¹ —CH ₂ —R ² —) _n —CH ₂ —R ¹ —CH ₂ —R ³ (I) (where R ¹ has a hydroxyl group) .R ^1, R ² a divalent aromatic group not, R ² is showing a divalent aromatic group having a hydroxyl group, R ³ is a monovalent aromatic group having a hydroxyl group, n represents 0 or an integer of 1 or more , R ³ may have respectively the same or different.) "4. "In the compound (A1), in the chemical formula (I), R1 is a divalent phenyl group, R2 is a divalent phenyl group having a hydroxyl group and R3 is a monovalent phenyl group having a hydroxyl group, or R1 is a divalent phenyl group. Any one of the above epoxy resin curing agents, wherein R is a divalent phenyl group having a hydroxyl group and R2 is a monovalent phenyl group having a hydroxyl group. " 5. The epoxy resin curing accelerator according to any one of the above, wherein the tetra-substituted phosphonium tetra-substituted borate (B) is tetraphenyl phosphonium tetraphenyl borate. 6. An epoxy resin composition comprising any one of the epoxy resin curing agent, epoxy resin, inorganic filler, and phenol curing agent as an optional component. "To the whole, the tetra-substituted phosphonium / tetra-substituted borate is 0.01 to 10% by weight, and the epoxy resin is 1 to 10% by weight.
15% by weight, the total amount of the phenolic resin and the phenolic curing agent is 1 to 15% by weight, and the inorganic filler is 50 to 9%.
The aforementioned epoxy resin composition that is 3% by weight. 8. 8. "Either of the above epoxy resin compositions for semiconductor encapsulation.""A semiconductor device in which a semiconductor element is sealed with the epoxy resin.""The phenolic resin (A) and the tetra-substituted phosphonium / tetra-substituted borate (B) are heated at 190 to 250 ° C.
A method for producing an epoxy resin curing accelerator, which comprises heating and mixing in the range described above. 11. 11. The method for producing any one of the epoxy resin curing accelerators described above, wherein the tetra-substituted phosphonium / tetra-substituted borate (B) is in a range of 3 to 30 parts by weight based on 100 parts by weight of the phenolic resin (A). "A method for producing any one of the epoxy resin curing accelerators described above, wherein the phenolic resin (A) contains 70% by weight or more of the phenolic resin (A1) represented by the chemical formula (I)."

Embedded image R ³ — (— CH ₂ —R ¹ —CH ₂ —R ² —) _n —CH ₂ —R ¹ —CH ₂ —R ³ (I) (where R ^{1 in} the formula has a hydroxyl group) .R ^1, R ² a divalent aromatic group not, R ² is showing a divalent aromatic group having a hydroxyl group, R ³ is a monovalent aromatic group having a hydroxyl group, n represents 0 or an integer of 1 or more , R ³ may be the same or different.) 13. "Compound (A1) is a compound represented by the formula (I) wherein R ¹ is 2
R ² is a divalent phenyl group having a hydroxyl group and R ³ is a monovalent phenyl group having a hydroxyl group, or R ¹ is a divalent biphenyl group having a hydroxyl group, and R ² is a divalent phenyl group having a hydroxyl group. The method for producing an epoxy resin curing agent according to any one of the above, wherein the phenyl group and R ³ are a monovalent phenyl group having a hydroxyl group. 14. "After producing an epoxy resin curing accelerator by any of the above methods, the epoxy resin curing agent, epoxy resin,
And heating and mixing an inorganic filler and a phenol curing agent as an optional component. ”.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail.
In the present invention, “weight” means “mass”.

The chemical structure of the phenolic resin (A) to be added to the curing accelerator of the present invention is arbitrary.
It is preferably contained at 0% by weight or more.

Embedded image R ³ — (— CH ₂ —R ¹ —CH ₂ —R ² —) _n —CH ₂ —R ¹ —CH ₂ —R ³ (I) (where R ¹ has a hydroxyl group) .R ^1, R ² a divalent aromatic group not, R ² is showing a divalent aromatic group having a hydroxyl group, R ³ is a monovalent aromatic group having a hydroxyl group, n represents 0 or an integer of 1 or more , R ³ may be the same or different.)

Other examples of the phenolic resin in the present invention include a novolak resin-based phenolic resin, a resin obtained by condensing paraxylylene methoxide and phenols, and a reaction product of diphenyl ether and phenols. Can be.

The mixing ratio of the compound represented by formula (I) is preferably from 70 to 100% by weight, more preferably from 80 to 100% by weight, even more preferably from 90 to 100% by weight of the component (A). It is.

In the curing catalyst of the present invention, it is preferable that the phenolic resin (A) and the tetra-substituted phosphonium / tetra-substituted borate (B) are substantially uniformly mixed.

In the present invention, an epoxy resin curing agent can be obtained by heating and mixing the phenolic resin (A) and the tetra-substituted phosphonium / tetra-substituted borate (B). The temperature at the time of heating and mixing is 190 to 2
50 ° C. is preferred, and more preferably 195 to 240 ° C.
And more preferably from 205 to 235 ° C. 19
When the temperature is lower than 0 ° C., the epoxy resin composition containing a curing accelerator is hardly cured, and when heated at a temperature higher than 250 ° C., thermal decomposition becomes active and is not suitable. The heating and mixing time is not particularly limited, but is, for example, 1 minute to
A one hour range is preferred.

In the method of producing the curing catalyst, the method of adding these components is not particularly limited. For example, after the tetra-substituted phosphonium / tetra-substituted borate and the phenolic resin (A) are put into a vessel and mixed with stirring,
Heating, stirring and mixing method, phenolic resin (A)
Is heated and melted, and while the molten compound is agitated, the tra-substituted phosphonium / tetra-substituted borate is gradually added, followed by heating and mixing. Although the heating device is not particularly limited, for example, an oil bath, an electric heater, an oven, or the like can be used. The heating atmosphere is not particularly limited, and examples thereof include an air atmosphere, a nitrogen atmosphere, and an argon atmosphere. Preferably, it is a nitrogen atmosphere.

The mixing ratio of the tetra-substituted phosphonium / tetra-substituted borate and the phenol resin in the curing accelerator is not particularly limited.
The amount of tetraphenylphosphonium / tetraphenylborate is preferably 3 to 30 parts by weight, more preferably 5 to 20 parts by weight, and still more preferably 7 to 15 parts by weight with respect to 00 parts by weight.

The epoxy resin curing accelerator obtained by the present invention is used by being blended into an epoxy resin composition.

The epoxy resin composition contains the epoxy resin curing agent, epoxy resin, inorganic filler, and phenol curing agent as an optional component. Since the curing accelerator of the present invention contains a compound having a plurality of phenol groups, the curing accelerator alone can contribute to the curing of the epoxy resin, but a phenolic curing agent can be further added as an optional component.

As the epoxy resin, cresol novolak type epoxy resin, phenol novolak type epoxy resin, biphenyl type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, complex resin Examples thereof include a cyclic epoxy resin, a spiro ring-containing epoxy resin, and a halogenated epoxy resin.

As the optional phenolic curing agent, known phenolic curing agents can be used, and phenol-novolak resins, cresol-novolak resins, various novolak resins synthesized from bisphenol A and resorcinol, tris (hydroxyphenyl) ) Various polyvalent phenol compounds such as methane, dihydroxybiphenyl and the compounds shown in the above (I).

The inorganic filler to be added to the resin composition of the present invention includes silica, calcium carbonate, magnesium carbonate, alumina, magnesia, magnesium aluminum oxide, zirconia, zircon, clay, talc,
Examples include calcium silicate, titanium oxide, antimony oxide, asbestos, and glass fibers.

In the epoxy resin composition, the amount of each component is 0.01 to 10% by weight of tetra-substituted phosphonium / tetra-substituted borate, 0.1 to 1% by weight, and epoxy resin is 1 to 15% by weight, further 2 to 10%, the total amount of the phenolic resin and the phenol curing agent is 1 to 15% by weight, further 2 to 10% by weight, and the inorganic filler is 50 to 93% by weight, and further 86 to 92%.
A range of weight% is preferred. In addition, the chemical equivalent ratio (epoxy / phenol) of the sum of the epoxy group of the epoxy resin and the phenol group in the phenolic resin and the phenol curing agent in the above compound is 0.5 to 2, and more preferably 0.8 to 0.8.
It is preferably in the range of 1.3.

Further, the epoxy resin composition may also contain the following flame retardants. Examples of the flame retardant include brominated bisphenol A type epoxy resin, brominated epoxy resin such as brominated phenol novolak type epoxy resin, brominated polycarbonate resin, brominated polystyrene resin, brominated polyphenylene oxide resin, tetrabromobisphenol A, Decabromodiphenyl ether and the like. It can also be used in the presence of the following flame retardant aids. Examples of the flame retardant aid include antimony trioxide, antimony tetroxide, and antimony pentoxide. It can also be used in the presence of the following compounds. Coloring agents such as carbon black and iron oxide; ion scavengers such as hydrotalcite; elastomers such as silicone rubber, olefin copolymer, modified nitrile rubber, modified polybutadiene rubber, and modified silicone oil;
Examples include thermoplastic resins such as polyethylene, long-chain fatty acids, metal salts of long-chain fatty acids, esters of long-chain fatty acids, amides of long-chain fatty acids, release agents such as paraffin wax, and crosslinking agents such as organic peroxides.

As a method for producing the epoxy resin composition of the present invention, the above compounds including a curing accelerator are kneaded by heating,
For example, a method of kneading at 50 to 170 ° C. is preferred. For example, melt kneading, solidifying, and, if necessary, tableting using a known kneading method such as a Banbury mixer, a kneader, a roll, a single or twin screw extruder and a co-kneader. Can be obtained. Further, the semiconductor device is obtained by heating and fluidizing the epoxy resin composition of the present invention, sealingly molding and curing the semiconductor element.

[0032]

The present invention will be described below in detail with reference to examples. The numbers in the composition tables in Tables 2 and 3 indicate% by weight.

Examples are shown in Table 2 and comparative examples are shown in Tables 2 and 3.

The components shown in Table 1 were prepared. The curing accelerators heated and kneaded here are those which are heated and kneaded at the composition ratios of the raw materials shown in Table 2 or Table 3 and at the temperatures shown in Table 2 or Table 3. When the curing accelerator used in Examples 1 to 4 after heating and kneading was visually observed, the raw materials were uniformly mixed.

Further, dry blending was performed by a mixer at the composition ratios shown in Tables 2 and 3. The roll surface temperature 9
After heating and kneading for 5 minutes using a mixing roll at 0 ° C., the mixture was cooled and pulverized to produce an epoxy resin composition for semiconductor encapsulation.

[0036]

[Table 1]

Various physical properties were measured by the following methods, and the results are shown in Tables 2 and 3.

Fluidity: 1 using an EMMI mold evaluation mold
Spiral flow was measured at 75 ° C. at a molding speed of 25 m / sec. Curability: A disk having a diameter of 4 inches and a thickness of 3 mm was molded at a molding temperature of 175 ° C. and a molding time of 60 seconds, and Barcol hardness immediately after molding was determined. If it is 70 or more, it can be said that it has sufficient curability. Crack resistance and peel resistance: In Examples and Comparative Examples, 10 pieces each of 160 pins QFP (outer size: 28 × 28
× 3.3 mm, simulated semiconductor device: 10 × 10 × 0.5 mm,
(Frame material: 42 alloy, chip surface: polyimide film) molded and cured at 175 ° C. for 4 hours, humidified at 85 ° C. and 85% RH for 168 hours, and then 260 ° C. 10 using an IR reflow furnace. Heat treatment was performed for seconds. Then, the number of external cracks is checked and the package containing the crack is determined to be a defective package, and the number is defined as n.
A value of (1-n / 10) × 100 was set as a numerical value indicating crack resistance.
The closer the value is to 100%, the better the crack resistance. On the other hand, when the sample heat-treated at 260 ° C. for 10 seconds using an IR reflow furnace was observed for peeling from the lead frame with an ultrasonic flaw detector, the peeled packages were regarded as defective packages, and the number of the packages was n (1-n / 10) The value of × 100 was used as a numerical value indicating crack resistance. The closer the value is to 100%, the better the peel resistance.

Storage stability: Based on the value of the spiral flow before storage, the composition was separately stored at 28 ° C. and 50% RH for 96 hours and then molded, and the reduction rate of the spiral flow value was expressed. The smaller the value, the better the storage stability.

[0040]

[Table 2]

As can be seen from Table 2, the epoxy resin compositions of Examples 1 to 4 have fluidity, curability, crack resistance,
Excellent in all physical properties such as peel resistance, storage stability, and mold stain. In contrast, the comparative example has crack resistance,
It turns out that it is inferior in any of peeling resistance, hardening property, crack resistance, peeling resistance, and mold contamination.

[0042]

[Table 3]

[0043]

The curing accelerator for epoxy resin of the present invention comprises:
A semiconductor device mainly used for transfer molding because it can obtain an epoxy resin composition which is excellent in fluidity and curability during molding, and provides a cured product having excellent crack resistance and storage stability during solder reflow. It is suitable for sealing.

Claims (17)

[Claims] An epoxy resin curing accelerator in which a phenolic resin (A) and a tetra-substituted phosphonium / tetra-substituted borate (B) are substantially uniformly mixed. 2. The epoxy resin curing accelerator according to claim 1, wherein the amount of the tetra-substituted phosphonium / tetra-substituted borate (B) is in the range of 3 to 30 parts by weight based on 100 parts by weight of the phenolic resin (A). 3. The epoxy resin curing accelerator according to claim 1, wherein the phenolic resin (A) contains at least 70% by weight of the phenolic resin (A1) represented by the chemical formula (I). Embedded image R ³ — (— CH ₂ —R ¹ —CH ₂ —R ² —) _n —CH ₂ —R ¹ —CH ₂ —R ³ (I) (where R ¹ has a hydroxyl group) .R ^1, R ² a divalent aromatic group not, R ² is showing a divalent aromatic group having a hydroxyl group, R ³ is a monovalent aromatic group having a hydroxyl group, n represents 0 or an integer of 1 or more , R ³ may be the same or different.) 4. A compound (A1) is in the formula (I), R ¹
The epoxy resin curing accelerator according to claim 3, wherein is a divalent phenyl group, R ² is a divalent phenyl group having a hydroxyl group, and R ³ is a monovalent phenyl group having a hydroxyl group. 5. The compound (A1) is in the formula (I), R ¹
Is a divalent biphenyl group, R ² is a divalent phenyl group having a hydroxyl group, and R ³ is a monovalent phenyl group having a hydroxyl group. 6. The epoxy resin curing accelerator according to claim 1, wherein the tetra-substituted phosphonium tetra-substituted borate (B) is tetraphenyl phosphonium tetraphenyl borate. 7. An epoxy resin composition comprising the epoxy resin curing agent according to claim 1, an epoxy resin, an inorganic filler and a phenolic curing agent as an optional component. 8. A tetra-substituted phosphonium.
0.01 to 10% by weight of tetra-substituted borate, 1 to 15% of epoxy resin, 1 to 15% of total amount of phenolic resin and phenolic curing agent, and 50 to 93 of inorganic filler
The epoxy resin composition according to claim 7, which is in terms of% by weight. 9. The epoxy resin composition according to claim 7, which is used for encapsulating a semiconductor. 10. The epoxy resin according to claim 9,
A semiconductor device in which a semiconductor element is sealed. 11. A phenolic resin (A) and a tetra-substituted phosphonium / tetra-substituted borate (B),
A method for producing an epoxy resin curing accelerator, comprising heating and mixing at a temperature of 50 ° C. 12. The epoxy resin curing accelerator according to claim 10, wherein the amount of the tetra-substituted phosphonium / tetra-substituted borate (B) is in the range of 3 to 30 parts by weight based on 100 parts by weight of the phenolic resin (A). Method. 13. The phenolic resin (A) has a chemical formula (I)
The method for producing an epoxy resin curing accelerator according to claim 11 or 12, which comprises at least 70% by weight of a phenolic resin (A1) represented by the formula: Embedded image R ³ — (— CH ₂ —R ¹ —CH ₂ —R ² —) _n —CH ₂ —R ¹ —CH ₂ —R ³ (I) (where R ¹ has a hydroxyl group) .R ^1, R ² a divalent aromatic group not, R ² is showing a divalent aromatic group having a hydroxyl group, R ³ is a monovalent aromatic group having a hydroxyl group, n represents 0 or an integer of 1 or more , R ³ may be the same or different.) 14. A compound (A1) represented by the formula (I):
14. The method according to claim 13, wherein ¹ is a divalent phenyl group, R ² is a divalent phenyl group having a hydroxyl group, and R ³ is a monovalent phenyl group having a hydroxyl group. 15. A compound (A1) represented by the formula (I):
14. The method for producing an epoxy resin curing agent according to claim 13, wherein ¹ is a divalent biphenyl group, R ² is a divalent phenyl group having a hydroxyl group, and R ³ is a monovalent phenyl group having a hydroxyl group. 16. An epoxy resin curing accelerator produced by the method according to any one of claims 10 to 14, followed by heating and mixing said epoxy resin curing agent, epoxy resin, inorganic filler and phenol curing agent as an optional component. A method for producing an epoxy resin composition, comprising: 17. The method for producing an epoxy resin composition according to claim 16, wherein the epoxy resin composition is for semiconductor encapsulation.