JP2005281597A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition for sealing semiconductors, which does not contain a halogen-based flame retardant and an antimony compound, has an excellent moldability, flame retardancy and soldering resistance. <P>SOLUTION: The epoxy resin composition comprises: (A) an epoxy resin, (B) a phenol resin, (C) a cure accelerator, (D) an inorganic filler, (E) at least one kind of flame retardants selected from aluminum hydroxide, a metal hydroxide solid solution and zinc borate and (F) a coupling agent having a secondary amino group. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an epoxy resin composition for semiconductor encapsulation and a semiconductor device.

Conventionally, electronic components such as diodes, transistors, and integrated circuits are mainly sealed with an epoxy resin composition. In these epoxy resin compositions, a halogen-based flame retardant and an antimony compound are blended in order to impart flame retardancy. However, development of an epoxy resin composition excellent in flame retardancy is required without using halogen-based flame retardants and antimony compounds from the viewpoint of environment and hygiene.
In addition, when a semiconductor device sealed with an epoxy resin composition containing a halogen-based flame retardant and an antimony compound is stored at a high temperature, the thermally decomposed halide is liberated from these flame retardant components, and the junction of the semiconductor element It is known that the reliability of semiconductor devices will be corroded, and an epoxy resin composition capable of achieving flame retardant grade V-0 is required without using halogenated flame retardants and antimony compounds as flame retardants. ing.
In this way, the corrosion resistance of the semiconductor element junction (bonding pad) after storing the semiconductor device at a high temperature (for example, 185 ° C.) is called the high temperature storage characteristic, and this high temperature storage characteristic is improved. As a technique to do so, a method using diantimony pentoxide (for example, refer to Patent Document 1), a method of combining antimony oxide and an organic phosphine (for example, refer to Patent Document 2), etc. have been proposed, and the effects have been confirmed. However, some of the types of epoxy resin compositions are unsatisfactory with respect to the high level required for high-temperature storage characteristics for recent semiconductor devices.

In addition, zinc borate has been proposed as a flame retardant, flame retardant grade V-0 can be achieved by adding a large amount, and there is no problem with high temperature storage characteristics, but moisture addition reliability, moldability, There is a problem that solder resistance is lowered.
Flame retardant by using a specific metal hydroxide and a specific metal oxide in combination or a composite metal hydroxide of a specific metal hydroxide and a specific metal oxide as a technique for improving the above-mentioned drawbacks Has been proposed (see, for example, Patent Documents 3 and 4), but a large amount of addition is required to exhibit sufficient flame retardancy. There is a problem that causes sex decline.
That is, there is a demand for an epoxy resin composition that maintains flame retardancy, is excellent in moldability, high-temperature storage characteristics, moisture resistance reliability, and solder resistance and does not use a halogen-based flame retardant and an antimony compound.
JP 55-146950 A Japanese Patent Laid-Open No. 61-53321 JP-A-10-251486 (pages 2 to 13) Japanese Patent Laid-Open No. 11-11945 (pages 2-14)

  The present invention relates to an epoxy resin composition for semiconductor encapsulation that does not contain a halogen-based flame retardant and an antimony compound and has excellent moldability, flame retardancy, and solder resistance, and a semiconductor element using the same. A semiconductor device is provided.

The present invention
[1] (A) epoxy resin, (B) phenol resin, (C) curing accelerator, (D) inorganic filler, (E) magnesium hydroxide, aluminum hydroxide, zinc molybdate, general formula (1)
1) one or more flame retardants selected from a metal hydroxide solid solution represented by formula (2) or zinc borate represented by formula (2), and (F) a silane coupling agent represented by formula (3) An epoxy resin composition for semiconductor encapsulation, characterized by being an essential component,
Mg _1-y M ²⁺ _y (OH) ₂ (1)
( ^Wherein M ²⁺ represents at least one divalent metal ion selected from the group consisting of Mn ²⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ , Cu ^2+, and Zn ²⁺ ; 0.01 ≦ y ≦ 0.5.)
pZnO · qB ₂ O ₃ · rH ₂ O (2)
(In the formula, p, q and r are positive numbers.)

（Ｒ¹は炭素数１〜１２の有機基、Ｒ²、Ｒ³、Ｒ⁴は炭素数１〜１２の炭化水素基、ｎは１〜３の整数。）

(R ¹ is an organic group having 1 to 12 carbon atoms, R ² , R ³ and R ⁴ are hydrocarbon groups having 1 to 12 carbon atoms, and n is an integer of 1 to 3)

[2] One or more kinds of difficulties selected from magnesium hydroxide, aluminum hydroxide, zinc molybdate, metal hydroxide solid solution represented by general formula (1), or zinc borate represented by general formula (2) The epoxy resin composition for semiconductor encapsulation according to item [1], wherein the flame retardant (E) is previously surface-treated with a silane coupling agent (F) represented by the general formula (3),
[3] A semiconductor device comprising a semiconductor element sealed with the epoxy resin composition according to the item [1] or [2],
It is.

According to the present invention, an epoxy resin composition for semiconductor encapsulation that does not contain a halogen-based flame retardant and an antimony compound and is excellent in moldability is obtained, and a semiconductor device using the same has flame resistance and solder resistance. Excellent.

  The epoxy resin composition of the present invention exhibits flame retardancy without using a halogen-based flame retardant and an antimony compound by using a specific flame retardant and a coupling agent having a specific secondary amino group. It has been found that it has excellent properties and solder resistance.

Hereinafter, the present invention will be described in detail.
The epoxy resin used in the present invention refers to monomers, oligomers, and polymers in general having two or more epoxy groups in one molecule, and the molecular weight and molecular structure thereof are not particularly limited. For example, biphenyl type epoxy resins, Bisphenol type epoxy resin, stilbene type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenolmethane type epoxy resin, alkyl modified triphenolmethane type epoxy resin, triazine nucleus-containing epoxy resin, dicyclopentadiene modified phenol type Examples thereof include an epoxy resin and a phenol aralkyl type epoxy resin (having a phenylene skeleton, a biphenylene skeleton, etc.), and these may be used alone or in combination.

The phenol resin used in the present invention refers to monomers, oligomers, and polymers generally having two or more phenolic hydroxyl groups in one molecule, and its molecular weight and molecular structure are not particularly limited. For example, phenol novolak resin, Examples include cresol novolac resins, dicyclopentadiene-modified phenol resins, terpene-modified phenol resins, triphenolmethane resins, phenol aralkyl resins (having a phenylene skeleton, biphenylene skeleton, etc.), and these may be used alone or in combination. There is no problem.
Moreover, about the equivalent ratio of the epoxy group of all epoxy resins and the phenolic hydroxyl group of a phenol resin, the range of epoxy group number / phenolic hydroxyl group number = 0.7-1.5 is preferable, and if it remove | deviates from this range, an epoxy resin composition This is not preferable because the curability of the product is lowered, the glass transition temperature of the cured product is lowered, and the moisture resistance reliability is lowered.

  As a hardening accelerator used for this invention, what is necessary is just to accelerate | stimulate the hardening reaction of an epoxy group and a phenolic hydroxyl group, and what is generally used for the sealing material can be used. Examples thereof include 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, 2-methylimidazole, tetraphenylphosphonium / tetraphenylborate and the like. These may be used alone or in combination. Absent.

  Examples of the inorganic filler used in the present invention include fused silica, spherical silica, crystalline silica, secondary agglomerated silica, porous silica, silica obtained by pulverizing secondary agglomerated silica or porous silica, alumina, silicon nitride, and the like. However, fused silica powder and crystalline silica powder are preferred. The shape of the inorganic filler may be either crushed or spherical, but it is highly filled to improve solder resistance, and in addition, spherical fused silica powder from the viewpoint of balance of flow characteristics, mechanical strength and thermal characteristics. Is preferred. The maximum particle size is preferably 75 μm or less, and the average particle size is preferably 5 to 35 μm. If it is out of this range, the fluidity of the epoxy resin composition is lowered, and deformation of elements in the semiconductor device such as unfilling at the time of molding or chip shift is likely to occur, which is not preferable. A wide particle size distribution is effective for reducing the melt viscosity of the epoxy resin composition during molding. These inorganic fillers may be used alone or in combination. Further, a surface treated beforehand with a silane coupling agent or the like may be used. As the blending amount of the inorganic filler, the total amount of the flame retardant referred to in the present invention and the inorganic filler is 65 to 93% by weight in the total epoxy resin composition from the balance of moldability and solder resistance. It is preferable. Below the lower limit, the moisture absorption of the cured product of the epoxy resin composition increases and the strength at the soldering process temperature decreases, so that the semiconductor device is likely to crack during the soldering process and exceeds the upper limit. Then, the fluidity at the time of molding of the epoxy resin composition is lowered, and unfilling or pad shift of the semiconductor element is likely to occur, which is not preferable. However, blending as many inorganic fillers as possible reduces the moisture absorption rate of the cured epoxy resin composition and improves solder resistance. Therefore, blending as much as possible within the allowable range of fluidity during molding. Is preferred.

Magnesium hydroxide, aluminum hydroxide, zinc molybdate, a metal hydroxide solid solution represented by the general formula (1), or zinc borate represented by the general formula (2) used in the present invention acts as a flame retardant. is there.
As the flame retardant mechanism of magnesium hydroxide, aluminum hydroxide and the metal hydroxide solid solution represented by the general formula (1), the metal hydroxide starts dehydration during combustion and inhibits the combustion reaction by absorbing heat. It is. It is also known to promote carbonization of the cured resin and is considered to form a flame retardant layer that blocks oxygen on the surface of the cured product.
Furthermore, the metal hydroxide solid solution represented by the general formula (1) has an effect of appropriately reducing the endothermic start temperature and improving the flame retardancy. If the endothermic start temperature is low, the moldability and reliability are adversely affected, and if the endothermic start temperature is higher than the decomposition temperature of the cured resin, the flame retardancy decreases, but the endothermic start of the metal hydroxide solid solution used in the present invention The temperature is an appropriate value around 300 to 350 ° C. Particularly preferable M ²⁺ in the general formula (1) is Ni ²⁺ or Zn ²⁺ . The average particle diameter of the metal hydroxide solid solution represented by the general formula (1) is 0.5 to 30 μm, more preferably 0.5 to 10 μm.

Zinc borate represented by the general formula (2) used in the present invention, 2ZnO · 3B ₂ from balance between flame retardancy and moisture resistance reliability O ₃ · 3.5 H ₂ O and _{4ZnO · B 2 O 3 · H} 2 O In particular, 2ZnO.3B ₂ O ₃ .3.5H ₂ O exhibits high flame retardancy. As an average particle diameter, it is 1-30.
It is μm, more preferably 5 to 20 μm.

  Zinc molybdate used in the present invention is conventionally known to be effective as a smoke suppressant and flame retardant for vinyl chloride resins. As for the flame retardant mechanism, it is known that zinc molybdate promotes carbonization of the cured resin during combustion, which blocks the oxygen from the air, stops the combustion and achieves flame retardancy. It is thought. Zinc molybdate may be used alone, but it tends to absorb moisture. When the blending amount is increased, the moisture absorption rate of the semiconductor device increases, solder resistance may decrease, and moldability also decreases. . Therefore, by coating inorganic materials such as fused spherical silica and talc with zinc molybdate as a core material, only the surface zinc molybdate acts as a flame retardant, and the moisture absorption rate increases due to the zinc molybdate alone compounded. And moldability can be improved. The average particle size of the fused spherical silica, talc or the like coated with zinc molybdate is preferably 0.5 to 30 μm, and the maximum particle size is preferably 75 μm or less.

Magnesium hydroxide, aluminum hydroxide, zinc molybdate, metal hydroxide solid solution represented by the general formula (1), or zinc borate represented by the general formula (2) each has a property of imparting flame retardancy. However, a large amount of blending is required to develop sufficient flame retardancy. Mixing in a large amount tends to cause a decrease in fluidity, moldability, and strength, and solder resistance decreases. In order to prevent the deterioration of these various characteristics, it is necessary to reduce the blending amount as much as possible. By using each flame retardant together, the flame retardancy is further improved as a synergistic effect, and the blending amount can be reduced.
Further, the blending amount of magnesium hydroxide, aluminum hydroxide, zinc molybdate, metal hydroxide solid solution represented by general formula (1), or zinc borate represented by general formula (2) is not particularly limited. 0.1-10 weight% is preferable in an epoxy resin composition, and 0.5-5 weight% is more preferable.
Each flame retardant generates endotherm during combustion, and magnesium hydroxide, aluminum hydroxide, metal hydroxide solid solution represented by the general formula (1), or zinc molybdate promotes carbonization of the cured resin. The zinc borate of general formula (2) has the effect of improving the strength of the carbonized layer by forming a glassy film. Although the reason is not clear, by using these together, it is possible to supplement each other's ability and obtain high flame retardancy as a synergistic effect. As a result, flame retardancy can be maintained even if the blending amount is reduced, and fluidity, moldability, strength deterioration, and the like can be prevented.

  The silane coupling agent represented by the general formula (3) used in the present invention is a silane compound containing an amino group and all of the amino groups being secondary amino groups. Specific examples of these silane coupling agents include the following compounds, but are not limited thereto. These may be used alone or in combination of two or more.

In the system to which the above flame retardant is added according to the present invention, when a well-known silane coupling agent having a primary amino group is used, a decrease in strength due to the addition of the flame retardant can be suppressed. Viscosity increases and fluidity further decreases. On the other hand, by using the silane coupling agent of the present invention, low viscosity is achieved, and both strength reduction and fluidity reduction due to the addition of the flame retardant can be suppressed. Of these, C ₆ H ₅ NHC ₃ H ₆ Si (OCH ₃ ) ₃ is most desirable.
Furthermore, by subjecting the flame retardant of the present invention to a surface treatment with the silane coupling agent represented by the general formula (3), the coupling agent is chemically bonded to the surface of the flame retardant to form a film that is easily compatible with organic matter. Excellent compatibility with resin, and dispersibility of flame retardant in resin is improved. For this reason, sufficient flame retardance can be expressed by addition of a small amount, and strength reduction and fluidity reduction due to addition of the flame retardant can be suppressed.
As a method of treating the surface of the flame retardant with the silane coupling agent represented by the general formula (3), after pre-mixing the flame retardant with a super mixer at room temperature, the coupling agent is diluted as it is or in an appropriate solvent. And a method of obtaining a treated flame retardant by further stirring and the like.
The amount of the silane coupling agent represented by the general formula (3) is not particularly limited, but is preferably 0.01 to 3% by weight, more preferably 0.05 to 1% by weight in the total epoxy resin composition. . If the lower limit is not reached, sufficient strength and fluidity may not be obtained, and if the upper limit is exceeded, curability may be reduced.

The epoxy resin composition of the present invention has components (A) to (E) as essential components, but in addition to this, a coupling agent such as γ-glycidoxypropyltrimethoxysilane, carbon black, etc. Various additives such as colorants, release agents such as natural wax and synthetic wax, and low-stress additives such as silicone oil and rubber may be appropriately blended.
In addition, the epoxy resin composition of the present invention is sufficiently kneaded with a hot roll or a kneader after the components (A) to (E) and other additives are sufficiently uniformly mixed using a mixer or the like. It is obtained by pulverizing after cooling.
The epoxy resin composition of the present invention is used to encapsulate various electronic components such as semiconductors and to manufacture a semiconductor device by curing by conventional molding methods such as transfer molding, compression molding, and injection molding. That's fine.

Examples of the present invention are shown below, but the present invention is not limited thereto. The blending ratio is parts by weight.
In addition, the detail of the flame retardant surface-treated with the epoxy resin, phenol resin, silane coupling agent, and silane coupling agent used in Examples and Comparative Examples is shown below.
Epoxy resin A: biphenyl type epoxy resin (melting point 105 ° C., epoxy equivalent 185)
Epoxy resin B: Cresol novolac type epoxy resin (softening point 62 ° C., epoxy equivalent 210)
Phenol resin A: Phenol aralkyl resin (softening point 62 ° C., hydroxyl group equivalent 168)
Phenol resin B: Phenol novolak resin (softening point 81 ° C., hydroxyl group equivalent 105)
Silane coupling agent A: Coupling agent represented by formula (4) (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-573)

  Silane coupling agent B: Coupling agent represented by formula (7) (X12-806, manufactured by Shin-Etsu Chemical Co., Ltd.)

Example of production of flame retardant surface-treated with silane coupling agent Flame retardant A: 50% by weight of metal hydroxide solid solution (Mg _0.8 Zn _0.2 (OH) ₂ , average particle size 1 μm) and zinc borate (2ZnO · 3B ₂ O ₃・ 3.5H ₂ O, average particle size 10 μm) 50% by weight
While stirring at room temperature using a supermixer, 1% by weight of silane coupling agent A was added dropwise, stirring was continued for 5 minutes, and the mixture was allowed to stand at room temperature for 4 hours to obtain flame retardant A.
Flame retardant B: 50% by weight of aluminum hydroxide (average particle size 3 μm) and 50% by weight of zinc borate (2ZnO.3B ₂ O ₃ .3.5H ₂ O, average particle size 10 μm) are stirred at room temperature using a super mixer. Then, 1% by weight of silane coupling agent A was added dropwise, and stirring was continued for 5 minutes. Then, the mixture was allowed to stand at room temperature for 4 hours to obtain flame retardant B.
Flame retardant C: 50% by weight of metal hydroxide solid solution (Mg _0.8 Zn _0.2 (OH) ₂ , average particle size 1 μm) and zinc borate (2ZnO.3B ₂ O ₃ .3.5H ₂ O, average particle size 10 μm) 50 weight%
While stirring at room temperature using a supermixer, 1% by weight of silane coupling agent B was added dropwise, stirring was continued for 5 minutes, and the mixture was allowed to stand at room temperature for 4 hours to obtain flame retardant C.
Flame retardant D: 50% by weight of metal hydroxide solid solution (Mg _0.8 Zn _0.2 (OH) ₂ , average particle size 1 μm) and zinc borate (2ZnO.3B ₂ O ₃ .3.5H ₂ O, average particle size 10 μm) 50 weight%
While stirring at room temperature using a supermixer, 1% by weight of γ-aminopropyltrimethoxysilane was added dropwise, and stirring was continued for 5 minutes. Then, the mixture was left at room temperature for 4 hours to obtain flame retardant D.

Example 1
Epoxy resin A 77 parts by weight Phenol resin A 70 parts by weight 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU)
2 parts by weight Fused spherical silica (average particle size 23 μm, maximum particle size 75 μm) 790 parts by weight Flame retardant A 50 parts by weight γ-glycidoxypropyltrimethoxysilane 3 parts by weight Carbon black 3 parts by weight Carnauba wax 5 parts by weight The mixture was mixed with a super mixer, roll-kneaded at 70 to 100 ° C., cooled and pulverized to obtain an epoxy resin composition. The obtained epoxy resin composition was evaluated by the following methods. The results are shown in Table 1.

Evaluation method Spiral flow: Measurement was performed at a mold temperature of 175 [deg.] C., an injection pressure of 6.9 MPa, and a curing time of 120 seconds using a mold for measuring a spiral flow according to EMMI-1-66. The unit is cm.
Flame retardancy: Using a transfer molding machine, mold a test piece (length 5 inch x width 1/2 inch x thickness 1/8 inch) with a mold temperature of 175 ° C, an injection pressure of 9.8 MPa, and a curing time of 120 seconds. After curing at 175 ° C. for 4 hours as a cure, a UL-94 vertical test was performed to determine flame retardancy.
Strength during heating: After molding a test piece (80 mm × 10 mm × 4 mm) at a molding temperature of 175 ° C., a pressure of 9.8 MPa, a curing time of 120 seconds using a transfer molding machine, and post-curing at 175 ° C. for 4 hours. The bending strength at 260 ° C. was measured according to JIS K 6911. The unit is N / mm ² .
Solder resistance 1: 80 pQFP using a transfer molding machine at a molding temperature of 175 ° C., a pressure of 9.8 MPa, and a curing time of 120 seconds (package size is 14 × 20 mm, thickness is 2 mm, silicon chip size is 7.0 × 7.0 mm) The lead frame was made of Cu), and 10 packages heat treated at 175 ° C. for 4 hours as post cure were humidified for 168 hours in an environment of 60 ° C. and 60% relative humidity, and then IR reflow treatment (260 ° C). The presence or absence of internal peeling or cracks after the IR reflow treatment was observed with an ultrasonic flaw detector, and the number of defective packages was counted. When the number of defective packages is n, n / 10 is displayed.
Solder resistance 2: 80 pQFP using a transfer molding machine at a molding temperature of 175 ° C., a pressure of 9.8 MPa and a curing time of 120 seconds (package size is 14 × 20 mm, thickness is 2 mm, silicon chip size is 7.0 × 7.0 mm) The lead frame is made of Cu), and 10 packages heat treated at 175 ° C. for 4 hours as post-cure were humidified for 168 hours in an environment of 30 ° C. and 70% relative humidity, and then IR reflow treatment (260 ° C). The presence or absence of internal peeling or cracks after IR reflow treatment was observed with an ultrasonic flaw detector, and the number of defective packages was counted. When the number of defective packages is n, n / 10 is displayed.

Examples 2-8, Comparative Examples 1-6
According to the composition of Tables 1 and 2, an epoxy resin composition was prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

According to the present invention, an epoxy resin composition for semiconductor encapsulation excellent in moldability, which does not contain a halogen-based flame retardant and an antimony compound, is obtained, and a semiconductor device using the same has flame resistance and solder resistance. Since it is excellent, it can be suitably used for semiconductor devices such as diodes, transistors, and integrated paths.

Claims (3)

(A) epoxy resin, (B) phenol resin, (C) curing accelerator, (D) inorganic filler, (E) magnesium hydroxide, aluminum hydroxide, zinc molybdate, metal represented by general formula (1) One or more flame retardants selected from hydroxide solid solution or zinc borate represented by the general formula (2) and (F) a silane coupling agent represented by the general formula (3) are essential components. An epoxy resin composition for encapsulating a semiconductor.
Mg _1-y M ²⁺ _y (OH) ₂ (1)
( ^Wherein M ²⁺ represents at least one divalent metal ion selected from the group consisting of Mn ²⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ , Cu ^2+, and Zn ²⁺ ; 0.01 ≦ y ≦ 0.5.)
pZnO · qB ₂ O ₃ · rH ₂ O (2)
(In the formula, p, q and r are positive numbers.)

(R ¹ is an organic group having 1 to 12 carbon atoms, R ² , R ³ and R ⁴ are hydrocarbon groups having 1 to 12 carbon atoms, and n is an integer of 1 to 3) One or more flame retardants (E) selected from magnesium hydroxide, aluminum hydroxide, zinc molybdate, metal hydroxide solid solution represented by general formula (1), or zinc borate represented by general formula (2) The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the surface treatment is performed in advance with a silane coupling agent (F) represented by the general formula (3). A semiconductor device comprising a semiconductor element sealed with the epoxy resin composition according to claim 1.