JP3116577B2 - Epoxy composition for semiconductor encapsulation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy composition for semiconductor encapsulation which is excellent in moldability, solder heat resistance and humidity resistance, and high-temperature reliability.

[0002]

2. Description of the Related Art Conventionally, as a method of sealing an electronic component such as a semiconductor, a hermetic seal using a metal or ceramic and a resin sealing using an epoxy resin, a silicone resin, a phenol resin or the like have been performed. However, resin encapsulation is mainly used to improve productivity and reduce manufacturing costs.

[0003] Epoxy resins are excellent in mechanical properties (strength), electrical properties (insulating properties), heat resistance, adhesiveness and the like. Further, it is widely used as a sealing resin because it is more advantageous than other resins in terms of price.

On the other hand, recently, electronic components have been surface-mounted on printed wiring boards as electronic devices have become smaller, faster, and lower in cost. In the surface mounting method, the entire electronic component is heated to a high temperature of 210 to 260 ° C. in the soldering process. When heated, resin and semiconductor (chip)
Thermal stress occurs due to the difference in linear expansion coefficient of The chip is damaged by the thermal stress, and the interface between the chip and the resin is separated. At this time, if the semiconductor resin package absorbs moisture, the moisture inside the resin explosively evaporates and is supplied to the peeled portion, and the resin cracks. A semiconductor component in such a state is defective because reliability cannot be obtained.

[0005] As a countermeasure, a method has been adopted in which the package after post-curing is dried, stored in an airtight container and shipped.

Further, when a semiconductor is sealed with an epoxy resin, thermal stress is applied to the semiconductor element due to a temperature change due to a difference in coefficient of linear expansion between the two, and aluminum wiring slides and current leaks, and a passivation film or a sealing film is formed. There is a problem that cracks occur in the resin itself and reliability is reduced.

To solve these problems, it is effective to reduce the stress of the sealing resin. In order to reduce the stress of the sealing resin, the following two methods can be considered. One method is to select the type of filler or to fill the filler with high density to lower the linear expansion coefficient of the sealing material. Second, there is a method of adding an elastomer component, which is a flexible agent, to lower the elastic modulus of the sealing material. For example, a method of adding a styrenic block copolymer (JP-A-63-251419) and a method of adding a modified silicone polymer (JP-A-6-251419)
No. 2-254454) has been proposed.

In order to improve the moisture resistance of the sealing resin, a hydrotalcite-based compound is added (Japanese Unexamined Patent Publication No.
No. 19625) has been proposed.

[0009]

Storing the package in an airtight container has the disadvantage that the workability is poor and the product price is high, and the filling of the filler at a high density increases the viscosity of the sealing material. However, there is a problem that moldability is deteriorated such as generation of voids in the molded product.

The encapsulant to which the unmodified styrene block copolymer is added does not sufficiently relax the stress with the chip, has a problem in solder heat resistance, and has a problem in that there are many flashes during molding. Although the reliability is improved by the addition of the hydrotalcite-based compound, no improvement in solder heat resistance is observed.

An object of the present invention is to reduce the thermal stress between a resin and a chip in a soldering process, to suppress the separation of the interface between the resin and the chip, and to suppress the occurrence of cracks in the resin package, thereby improving the reliability and improving the moldability. Excellent, such as around semiconductors and automobile engines that generate a large amount of heat
An object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation having excellent reliability in a high temperature environment of 0 ° C.

[0012]

The present inventors have achieved the above object by adding a modified styrene-based block copolymer, a hydrotalcite-based compound and antimony tetroxide, and have achieved the object of semiconductor encapsulation. The present inventors have found that an epoxy composition for use can be obtained, and have reached the present invention.

That is, the present invention provides an epoxy resin (A),
A resin composition comprising, as essential components, a curing agent (B), a filler (C), a modified styrene-based block copolymer (D) and a hydrotalcite-based compound (E), wherein the modified styrene-based block The copolymer (D) is obtained by copolymerizing or grafting an unsaturated carboxylic acid or a derivative thereof to a styrene-based block copolymer, and the hydrotalcite-based compound (E) is present in an amount of 0.01 to 10% by weight.
Epoxy composition for semiconductor encapsulation characterized by containing
And a semiconductor device sealed using the same .

Hereinafter, the configuration of the present invention will be described in detail.

The epoxy resin (A) according to the present invention comprises:
There is no particular limitation as long as it has two or more epoxy groups in the molecule.

For example, cresol novolak epoxy resin, phenol novolak epoxy resin, biphenyl epoxy resin, various novolak epoxy resins synthesized from bisphenol A and resorcin, bisphenol A epoxy resin, linear aliphatic epoxy resin,
Examples include alicyclic epoxy resins, heterocyclic epoxy resins, halogenated epoxy resins, and spiro ring-containing epoxy resins.

Depending on the application, two or more epoxy resins may be used in combination. However, from the viewpoint of heat resistance and moisture resistance, the epoxy resin equivalent of a cresol novolak type epoxy resin, a biphenyl type epoxy resin, etc. is 500 or less, especially 30.
50% by weight or less of epoxy resin in total epoxy resin
It is preferable to include the above.

In the present invention, the amount of the epoxy resin (A) is usually 4 to 25% by weight, preferably 6 to 18% by weight.
It is.

The curing agent (B) in the present invention is not particularly limited as long as it is cured by reacting with the epoxy resin (A). Specific examples thereof include phenol novolak resin, cresol novolak resin, bisphenol A and various novolak resins synthesized from resorcinol, phenolic curing agents such as various polyhydric phenol compounds, acid anhydrides such as maleic anhydride, phthalic anhydride, and pyromellitic anhydride and metaphenylenediamine, diaminodiphenylmethane, diaminodiphenyl And aromatic amines such as sulfone. For semiconductor encapsulation, a phenolic curing agent is preferably used from the viewpoint of heat resistance, moisture resistance and storage stability, and two or more curing agents may be used in combination depending on the application.

In the present invention, the amount of the curing agent (B) is usually 1 to 15% by weight, preferably 3 to 10% by weight. Further, the compounding ratio of the epoxy resin (A) and the curing agent (B) is such that the chemical equivalent ratio of (B) to (A) is 0.7 to 1.3, especially 0.1 to 0.3 in view of mechanical properties and moisture resistance. 8 ~
It is preferably in the range of 1.2.

In the present invention, the epoxy resin (A)
A curing catalyst may be used for accelerating the curing reaction between the resin and the curing agent (B). The curing catalyst is not particularly limited as long as it promotes the curing reaction. For example, 2-methylimidazole,
Imidazole compounds such as 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole, triethylamine, benzyldimethylamine, α-methylbenzyl Tertiary amine compounds such as dimethylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, 1,8-diazabicyclo (5,4,0) undecene-7, zirconium tetra Organometallic compounds such as methoxide, zirconium tetrapropoxide, tetrakis (acetylacetonato) zirconium, tri (acetylacetonato) aluminum and triphenylphosphine, trimethylphosphine;
Organic phosphine compounds such as triethylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine, and tri (nonylphenyl) phosphine are exemplified. Of these, organic phosphine compounds are preferred from the viewpoint of moisture resistance, and triphenylphosphine is particularly preferably used. These curing catalysts may be used in combination of two or more depending on the use.
The range of 0.5 to 5 parts by weight per 100 parts by weight is preferred.

As the filler (C) in the present invention, amorphous silica, crystalline silica, silicon nitride, silicon carbide,
Calcium carbonate, magnesium carbonate, alumina, magnesia, clay, talc, calcium silicate, titanium oxide, asbestos, glass fiber and the like can be added. Among them, amorphous silica is preferably used from the viewpoint of low stress.

In the present invention, the proportion of the filler (C) is
60-95% by weight of the whole in view of formability and low stress
It is. When amorphous silica is used as the filler (C), its proportion is preferably 60 to 90% by weight of the whole,
0-88% by weight is particularly preferred.

The modified styrenic block copolymer (D) in the present invention is obtained by copolymerizing or grafting an unsaturated carboxylic acid or a derivative thereof with a styrenic block copolymer. The styrene-based block copolymer has an aromatic vinyl hydrocarbon polymer block having a glass transition temperature of usually 25 ° C. or higher, preferably 50 ° C. or higher, and a conjugated diene polymer having a glass transition temperature of 0 ° C. or lower, preferably −25 ° C. or lower. Linear, radial and branched block copolymers composed of united blocks are included. Examples of the aromatic vinyl hydrocarbon include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, 1,3-dimethylstyrene, and vinylnaphthalene. Among them, styrene can be preferably used.

The conjugated diene includes butadiene (1,3-butadiene) and isoprene (2-methyl-
Among them, 1,3-butadiene), methyl isoprene (2,3-dimethyl-1,3-butadiene), 1,3-pentadiene and the like, butadiene and isoprene can be preferably used. The proportion of the aromatic vinyl hydrocarbon polymer block as the glass phase block in the styrene-based block copolymer is preferably 10 to 50% by weight, and the proportion of the conjugated diene polymer block as the rubber phase block is preferably 90 to 50% by weight. . There are many combinations of a glass phase block and a rubber phase block, and any of them may be used. However, a triblock copolymer in which a glass phase block is bonded to both ends of an intermediate rubber phase block is preferable. In this case, the number average molecular weight of the glass phase block is preferably 3,000 to 150,000, particularly preferably 5,000 to 60,000. The number average molecular weight of the rubber phase block is preferably from 5,000 to
300,000, particularly preferably 10,000 to 15
It is 0000.

The styrenic block copolymer can be produced by using a known living anionic polymerization method, but is not particularly limited thereto, and can also be produced by a cationic polymerization method or a radical polymerization method. The styrene-based block copolymer also includes a hydrogenated block copolymer in which a part of the unsaturated bonds of the block copolymer described above is reduced by hydrogenation. Here, it is preferable that 25% or less of the aromatic double bond of the aromatic vinyl hydrocarbon polymer block and 80% or more of the aliphatic double bond of the conjugated diene polymer block are hydrogenated. Preferred specific examples of the styrene-based block copolymer include polystyrene / polybutadiene / polystyrene triblock copolymer (S
BS), polystyrene / polyisoprene / polystyrene triblock copolymer (SIS), hydrogenated copolymer of SBS (SEBS) and hydrogenated copolymer of SIS. Among them, hydrogenated copolymer of SBS (S
Hydrogenated copolymers of EBS) and SIS are particularly preferably used.

The modified styrenic block copolymer (D) in the present invention is obtained by copolymerizing or grafting an unsaturated carboxylic acid or a derivative thereof with a styrenic block copolymer, and is usually produced by a grafting reaction. . Here, as the unsaturated carboxylic acid, acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, maleic acid,
Fumaric acid, itaconic acid, citraconic acid and butenedicarboxylic acid are preferably used. As the derivatives, alkyl esters, glycidyl esters, acid anhydrides, imides and the like are preferably used. Preferred specific examples include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, diglycidyl itaconate, and citraconic acid. Diglycidyl ester, butenedicarboxylic acid diglycidyl ester, butenedicarboxylic acid monoglycidyl ester, maleic anhydride, itaconic anhydride, citraconic anhydride, maleic imide, N-phenylmaleic imide, itaconic imide, citraconic imide, etc. Among them, glycidyl methacrylate, maleic anhydride, N-phenylmaleimide, and maleic imide are preferably used. These unsaturated carboxylic acids or derivatives thereof may be used in combination of two or more depending on the use.

The amount of the grafting reaction of the unsaturated carboxylic acid or its derivative is from 0.01 to 10 in view of improving the solder heat resistance.
% By weight, and particularly preferably from 0.05 to 5% by weight. Here, the graft reaction means that the unsaturated carboxylic acid or its derivative chemically bonds to the styrene-based block copolymer.

The modified styrenic block copolymer (D) can be prepared by a known method, for example, by subjecting a styrenic block copolymer and an unsaturated carboxylic acid or a derivative thereof to a molten state or a solution state in the presence of a radical initiator or It is obtained by performing a graft reaction in the absence. Preferably, a melt-kneading device such as a single-screw or twin-screw extruder, a Banbury mixer, a kneader, or a roll is used.
It can be manufactured by melt-kneading at 00 to 350 ° C. In addition, when an organic peroxide is added as a radical initiator during melt kneading, the graft reaction can be more effectively performed. As the organic peroxide, benzoyl peroxide, 1,
1-bis (tert-butylperoxy) -3,3,5
-Trimethylcyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valate, tert
-Butyl cumyl peroxide, dicumyl peroxide, tert-butyl peroxybenzoate, bis (tert-butyl peroxide), bis (tert
-Butylperoxy) diisopropylbenzene, 2,5
-Dimethyl-2,5-bis (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-bis (te
rt-butylperoxy) hexyne-3, tert-butylperoxycumene and the like. The amount of the organic peroxide to be added is preferably 0.001 to 1 part by weight based on 100 parts by weight of the styrene-based block copolymer.

The added amount of the modified styrene-based block copolymer (D) is preferably 0.1 to 10% by weight, particularly preferably 1 to 6% by weight in the epoxy composition for encapsulating a semiconductor, from the viewpoint of improving the solder heat resistance. .

Further, a styrene-based block copolymer can be added to the epoxy composition for semiconductor encapsulation of the present invention. The addition amount is preferably 10% by weight or less. Also,
The modified styrene-based block copolymer (D) and the styrene-based block copolymer may be used after being pulverized, crosslinked, or otherwise pulverized. The modified styrene-based block copolymer (D) and the styrene-based block copolymer can be mixed by any procedure. For example, a method of preliminarily melt-mixing with an epoxy resin (A) or a curing agent (B) and then blending other components, simultaneously with the epoxy resin (A), a curing agent (B), a filler (C) and other components. Examples of the method include a compounding method.

The hydrotalcite-based compound (E) in the present invention is a composite metal compound represented by the following formula (I) or (II).

The _{Mg x Al y (OH) 2x} + 3y-nz A z · mH 2 O ......... (I) Mg x Al y O (2x + 3y) / 2 ......... (II) ( provided that, A is n-valent anion a functional group capable of forming a ^n-, n is an integer of 1 to 3, x, y and z are 0 <y / x ≦
1, 0 or a positive number in a relationship of 0 ≦ z / y <1.5,
m represents 0 or a positive number. ) The formula (I), n-valent anion A ^n- preferred embodiment capable of generating a functional group ^{A, F -, Cl -, Br} -, I -, OH -,
^{_{HCO 3 -, CH 3 COO -}} , HCOO -, CO 3 2-,
SO ₄ ^2- , (COO ⁻ ) ₂ , tartrate ion [CH (O
H) COO ⁻ ] ₂ , citrate ion [C (OH) COO
⁻ ] (CH ₂ COO ⁻ ) ₂ , salicylate ion C ₆ H ₄
(OH) COO— ^{and the} like. Above all, CO ₃
^2- is particularly preferred.

The hydrotalcite-based compound (E) represented by the above formula (II) is obtained by calcining the hydrotalcite-based compound (E) represented by the above formula (I) at 400 to 900 ° C. It is manufactured by

A preferred specific example of the hydrotalcite-based compound (E) is Mg _4.5 Al ₂ (OH) ₁₃ CO _{3.
3.5H 2 O, Mg 4.5 A l2} (OH) 13 CO 3, Mg
₅ Al _1.5 (OH) ₁₃ CO ₃ · 3.5 H ₂ O, Mg ₅ A
l _1.5 (OH) ₁₃ CO ₃ , Mg ₆ Al ₂ (OH) ₁₆ CO
_{3 · 4H 2 O, Mg 6} Al 2 (OH) 16 CO 3, Mg
_0.65 Al _0.35 O _1.175 , Mg _0.7 Al _0.3 O _1.15 , Mg
_0.75 Al _0.25 O _1.125 , Mg _0.8 Al _0.2 O _{1.1 and the} like.

In the present invention, the addition amount of the hydrotalcite-based compound (E) is from 0.01 to 10% by weight, preferably from 0.02 to 5% by weight, particularly preferably from 0.05 to 5% by weight.
2% by weight. If the addition amount is less than 0.01% by weight, the effect of improving the high-temperature reliability is insufficient, and if it exceeds 10% by weight, the solder heat resistance decreases.

In the present invention, it is preferable to add antimony tetroxide (F) from the viewpoint of high temperature reliability. The amount of antimony tetroxide (F) added is 0.1 to 10
% By weight is preferred in terms of high-temperature reliability. Particularly preferably,
0.2 to 4% by weight.

In the present invention, it is preferable from the standpoint of reliability that the filler (C) be surface-treated in advance with a coupling agent such as a silane coupling agent or a titanate coupling agent. As the coupling agent, a silane coupling agent such as epoxy silane, amino silane, and mercapto silane is preferably used.

In addition, halogen compounds such as halogenated epoxy resins or flame retardants such as phosphorus compounds, flame retardant aids such as antimony trioxide, colorants such as carbon black and iron oxide, silicone rubber, modified nitrile rubber, Modified polybutadiene rubber, thermoplastic resin such as polyethylene, long chain fatty acid, metal salt of long chain fatty acid, ester of long chain fatty acid, amide of long chain fatty acid, paraffin wax, release agent such as silicone oil, organic peroxide, etc. Can be arbitrarily added.

The epoxy composition for semiconductor encapsulation of the present invention is preferably melt-kneaded. For example, melt-kneading is performed by using a known kneading method such as a Banbury mixer, a kneader, a roll, a single or twin screw extruder, and a co-kneader. It is manufactured by doing.

[0041]

The present invention will be described below in detail with reference to examples.

Examples 1 to 11 and Comparative Examples 1 to 8 The raw materials for the components shown in Tables 1 and 2 were dry-blended with the composition shown in Table 3 using a mixer. This is melt-kneaded using a twin-screw extruder with a barrel temperature of 90 ° C., and then cooled,
This was pulverized to produce an epoxy composition. The physical properties of this composition were measured by the following methods.

Molding was performed at 175 ° C. × 2 minutes by low pressure transfer molding and post-cured at 180 ° C. × 5 hours.

Flash (resin flash): Flash measurement Using a metal mold, the length of a transparent flash (resin flash) at a gap of 0 μm between the dies was measured.

Solder heat resistance: 44 pin QFP is molded,
After humidification at 85 ° C. and 85% RH, it was immersed in a solder bath heated to 260 ° C. for 10 seconds, and examined by an ultrasonic flaw detector whether or not the interface between the chip and the resin was separated. I asked.

Moisture resistance reliability (PCBT): 125 ° C./85% RH using 80 pin QFP equipped with a simulated device,
USPCBT was performed at a bias voltage of 10 V, and the time when the cumulative failure rate became 50% was determined as the life.

High temperature reliability: 64 pi after evaluation of solder heat resistance
Using nQFP, high-temperature reliability was evaluated at 175 ° C., and the time at which the cumulative failure rate became 50% was determined as the high-temperature life.

The results of the above evaluation are shown in Table 4.

[0049]

[Table 1]

[0050]

[Table 2]

[0051]

[Table 3]

[0052]

[Table 4]

It can be seen that the moldability (resin flash) and solder heat resistance of Examples 1 to 11 and Comparative Examples 1 and 6 containing the modified styrene block copolymer are excellent.

It can also be seen that the system containing the hydrotalcite-based compound and the antimony compound has excellent moisture resistance and high-temperature reliability. In particular, it can be seen that a system in which antimony tetroxide is selected as the antimony compound is remarkably excellent.

[0055]

The epoxy composition for encapsulating a semiconductor according to the present invention is industrially useful because it has excellent moldability, solder heat resistance, and high reliability under high temperature and humidity.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H01L 23/31 (56) References JP-A-4-50257 (JP, A) JP-A-3-255154 (JP, A) 54-31500 (JP, A) JP-A-2-175747 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 23/29, 23/31 C08L 63/00

Claims (3)

(57) [Claims] 1. An epoxy resin (A), a curing agent (B), a fused silica (C), and a modified styrene-based block copolymer (D).
And a hydrotalcite-based compound (E) as an essential component, wherein the modified styrene-based block copolymer (D) is a styrene-based block copolymer and an unsaturated carboxylic acid or a derivative thereof. Is a copolymer or a graft reaction, and contains 0.01 to 10% by weight of a hydrotalcite-based compound (E). 2. The epoxy composition for semiconductor encapsulation according to claim 1, further comprising antimony tetroxide (F). 3. The semiconductor according to claim 1, wherein
Characterized by being sealed with an epoxy composition for sealing
Semiconductor device.