CN1345896A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

An epoxy resin composition having excellent moldability and flame retardancy, a low water absorption rate, and excellent solder resistance. An epoxy resin composition for sealing a semiconductor, comprising an epoxy resin having an aromatic carbon atom content of 70% or more, (B) a phenol resin having an aromatic carbon atom content of 70% or more and a phenolic hydroxyl group equivalent of 140 to 300, (C) a curing accelerator, and (D) an inorganic filler having an addition amount W (wt%) of 88 to 94, wherein the cured epoxy resin composition has a combustion initiation temperature of 280 ℃ or more in TG curve analysis in an air atmosphere, and the residual ratio A (wt%) of the cured product satisfies W + [0.1 x (100-W) ] to A.

Description

Epoxy resin composition and semiconductor device

The present invention relates to an epoxy resin composition for encapsulating a semiconductor with low water absorption and excellent solder resistance, and to a semiconductor device using the composition.

In order to protect semiconductor elements from mechanical and chemical actions, epoxy resin compositions (hereinafter referred to as resin compositions) have been developed and produced in the past. Items required for the resin composition vary depending on the type of semiconductor element, the type of semiconductor device to be sealed, the environment in which it is used, and the like.

Since the increase of surface-mounted semiconductor devices requires a resin composition with a low water absorption rate, many resin compositions have been proposed.

Now, resin compositions that do not use halogen compounds and antimony oxide are strongly demanded due to environmental concerns. In response to this demand, various flame retardants other than halogen compounds and antimony oxide have been proposed, and resin compositions that do not use these flame retardants have been proposed. Proposal of resin composition for sealing with properties such as solder resistance.

The present invention provides an epoxy resin composition for semiconductor sealing excellent in moldability, flame retardancy, low water absorption and solder resistance, and a semiconductor device using the composition.

The present invention relates to an epoxy resin composition for encapsulation of a semiconductor, which contains: (A) an epoxy resin, wherein the content of aromatic carbon atoms in all carbon atoms of the epoxy resin is 70% or more, (B) phenolic resin, wherein, in the total carbon atoms of the phenolic resin, the content of aromatic carbon atoms is 70% or more, and the phenolic hydroxyl equivalent is 140 to 300, (C) curing accelerator , and (D) inorganic filler, its addition amount W (weight %) in whole epoxy resin composition is 88≤W≤94; It is characterized in that, the TG of cured epoxy resin composition in air atmosphere In the curve analysis (thermogravimetric analysis: thermogravimetric analysis), the combustion start temperature is 280° C. or higher. The present invention also relates to an epoxy resin composition for encapsulating a semiconductor, which contains: (A) an epoxy resin, wherein, among all the carbon atoms in the epoxy resin, the aromatic carbon atoms Content of 70% or more, (B) phenolic resin, wherein, in the total carbon atoms of the phenolic resin, the content of aromatic carbon atoms is 70% or more, and the phenolic hydroxyl equivalent is 140 to 300, (C) curing acceleration Agent, and (D) inorganic filler, its addition amount W (weight %) in whole epoxy resin composition is 88≤W≤94; It is characterized in that, the cured epoxy resin composition in air atmosphere In the TG curve analysis, the residual rate A (weight %) of the cured product satisfies W+[0.1×(100-W)]≦A. As a more preferred solution, the present invention also provides such an epoxy resin composition, wherein the epoxy resin is the epoxy resin shown in the general formula (1) or the epoxy resin shown in the general formula (2):

(R ₁ to R ₄ are hydrogen atoms, phenyl or methyl, which may be the same or different)

(R ₁ to R ₈ are hydrogen atoms, methyl groups or tert-butyl groups, which may be the same or different)

The phenolic resin is a phenolic resin represented by the general formula (3), a phenolic resin represented by the general formula (4), or a polycondensate of petroleum-based heavy oil and formaldehyde and a resin formed by polycondensation of phenols.

(n is the average value, a positive number greater than 1)

(R ₁ is a hydrogen atom or a methyl group, n is an average value, and is a positive number of 1 or more)

Furthermore, the present invention also provides a semiconductor device characterized in that it is obtained by sealing a semiconductor element with these compositions.

Fig. 1 is a schematic diagram expressing the relationship between the TG curve and the thermal decomposition initiation temperature.

The epoxy resin used in the present invention has an aromatic-derived carbon atom content of 70% or more in all carbon atoms of the epoxy resin. As the content of aromatic carbon atoms increases, the flame retardancy of the resin composition using the epoxy resin improves. Since this epoxy resin is excellent in flame retardancy, in the case of various phenolic resins used in combination as a curing agent described later, even if the resin composition of the present invention does not contain flame retardants such as halogen compounds or antimony oxide, It also has high flame retardancy and can maintain the V-0 level of UL-94. In addition, since the reactivity with the phenolic resin is good, the resin composition of the present invention is excellent in moldability and mechanical strength.

The aromatic-derived carbon atom used in the present invention includes carbon atoms directly bonded to these aromatic ring carbon atoms in addition to carbon atoms constituting aromatic rings such as benzene, naphthalene, anthracene, and pyrene. The carbon atom directly bonded to the aromatic ring is included in the carbon atom from the aromatic ring, and the reason is that the bond energy ratio of the carbon-carbon bond directly bonded to the aromatic ring is not the carbon-carbon bond directly bonded to the aromatic ring The bond energy of the bond is large, so it can be inferred that thermal decomposition is difficult.

The content of aromatic carbon atoms is calculated from the chemical structure of the epoxy resin. For example, in the case of toluene, since the methyl group is directly bonded to the aromatic ring and is included in the aromatic carbon atoms, the content of the aromatic carbon atoms is 100%. However, in the case of cumene, there are 6 carbon atoms constituting the aromatic ring, 1 non-aromatic carbon atom that is directly bonded to the aromatic ring, and 2 carbon atoms that are not directly bonded to the aromatic ring, Therefore, the content of aromatic-derived carbon atoms is calculated as (6+1)/(6+1+2)×100=78%.

As the epoxy resin used in the present invention, as long as it is an epoxy resin satisfying the above-mentioned conditions, it is not particularly limited, and the biphenyl type epoxy resin shown in general formula (1) can be enumerated, wherein particularly (3, 3',5,5')-tetramethyl-4,4'-bisphenol diglycidyl ether, and diphenyl-4,4'-bisphenol diglycidyl ether, or represented by general formula (2) Trans-stilbene-type (stilbene) epoxy resins, in addition, orthocresol-novolac (orthocresol-novolac) type diglycidyl ether, triphenolmethane type diglycidyl ether, bisphenol A type Epoxy resin, bisphenol F type epoxy resin, etc.

It should be noted that an epoxy resin having an aromatic carbon atom content of 70% or more may be used in combination with other epoxy resins. When used in combination, an epoxy resin containing 70% or more of aromatic carbon atoms is preferably used in an amount of 70% by weight or more of the entire epoxy resin. When it is less than 70% by weight, the flame retardancy decreases. The epoxy resin that can be used in combination is not particularly limited, and a dicyclopentadiene-modified novolac epoxy resin can be used suitably.

The epoxy resin used in the present invention is not particularly limited in terms of its characteristics such as melting point, softening point, melt viscosity, amount of ionic impurities, etc. However, the lower the amount of ionic impurities, the better the reliability, so it is preferable.

The phenolic resin used in the present invention has an aromatic-derived carbon atom content of 70% or more in all carbon atoms of the phenolic resin, and has a phenolic hydroxyl equivalent of 140-300. The calculation of the number of carbon atoms derived from aromatics is performed in the same manner as in the case of the above-mentioned epoxy resin.

It was found that when the phenolic hydroxyl group equivalent is less than 140, the functional group density per unit volume (the number of moles of phenolic hydroxyl group per unit volume) becomes high, and the flame retardancy decreases. Epoxy groups and phenolic hydroxyl groups tend to be thermally decomposed, and furthermore, flammable gases are generated during thermal decomposition, so if the number of moles of these functional groups increases, the flame retardancy remarkably decreases. It has been judged that reducing the number of moles of the above-mentioned functional groups, that is, reducing the density of the functional groups, is an effective means for improving flame retardancy. On the other hand, when the phenolic hydroxyl equivalent exceeds 300, the functional group density decreases too much and the reactivity decreases, so the curability decreases and the moldability deteriorates.

As the phenolic resin used in the present invention, phenolic resins represented by the general formula (3), naphthol aralkyl resins represented by the general formula (4), polycondensates of petroleum-based heavy oils and formaldehyde, and phenols are preferable. As modified phenolic resins obtained by condensation (disclosed in JP-A-7-252339 and JP-A-9-216927), phenol aralkyl resins can also be used. There are no particular limitations on the melting point, softening point, melt viscosity, and amount of ionic impurities that are characteristics of the phenolic resin of the present invention, but the smaller the amount of ionic impurities, the better the reliability, which is preferable.

The phenolic resin having an aromatic carbon atom content of 70% or more used in the present invention may be used in combination with other phenolic resins. When used in combination, the compounding amount of the phenolic resin having an aromatic carbon atom content of 70% or more is preferably 70% by weight or more of the total phenolic resin. If it is less than 70% by weight, the flame retardancy will decrease. The resins that can be used in combination are not particularly limited, but dicyclopentadiene-modified phenolic resins, novolac phenolic resins, and the like are preferred.

The equivalent ratio of the total number of epoxy groups of the epoxy resin used in the present invention to the total number of phenolic hydroxyl groups of the phenolic resin is preferably 0.5-2, more preferably 0.7-1.5. If it exceeds the range of 0.5 to 2, performances such as moisture resistance and curability will decrease, which is not preferable.

The curing accelerator used in the present invention is not particularly limited as long as it accelerates the reaction between the epoxy group and the phenolic hydroxyl group, and examples thereof include 1,8-diazabicyclo(5,4,0)undecene -7. Triphenylphosphine, tetraphenylphosphonium tetraphenyl borate, tetraphenylphosphonium tetrabenzoic acid borate, tetraphenylphosphonium tetranaphthoic acid borate, etc. They can be used alone or mixed use.

The kind of inorganic filler used in the present invention is not particularly limited, and inorganic fillers used in general sealing materials can be used. Examples include fused pulverized silica powder, fused spherical silica powder, crystalline silica powder, secondary aggregated silica powder, alumina, titanium dioxide, aluminum hydroxide, talc, clay, glass fiber, etc. , particularly preferably fused spherical silica powder. The shape is not limited, but it is preferably spherical, and the filling amount can be increased by mixing particles of different sizes.

The compounding ratio of the epoxy resin composition of the present invention is 5 to 10% by weight of the epoxy resin, 5 to 10% of the phenolic resin curing agent, and 0.05 to 2% of the curing accelerator for the entire epoxy resin composition. % by weight, the inorganic filler is 88 to 94% by weight. If the compounding ratio of the epoxy resin is less than 5% by weight, curing will be insufficient, and if it is more than 10% by weight, moldability will be deteriorated. If the blending ratio of the phenolic resin is less than 5% by weight, curing will be insufficient, and if it is more than 10% by weight, uncured matter will remain. If the compounding ratio of the curing accelerator is less than 0.05% by weight, it will take a long time to cure, and if it is more than 2% by weight, the curing will proceed rapidly and a satisfactory cured product cannot be obtained.

The inorganic filler used in the present invention must be added in an amount W (% by weight) of 88≦W≦94 in the entire resin composition. More preferably, it is 88 to 92% by weight. If the amount of inorganic filler is large, the water absorption rate will decrease, and at the same time, the incombustible inorganic filler competes for heat energy when exposed to flame, which can improve the flame retardancy of the cured resin composition. Furthermore, by increasing the modulus of the cured resin composition, good moldability (mold releasability) can be effectively achieved. When the amount of the inorganic filler is less than 88% by weight, the formed resin composition is easily combusted in a flame retardance test, has a high water absorption rate, and thus the solder resistance decreases. When the amount of the inorganic filler exceeds 94% by weight, the fluidity is remarkably lowered, and molding cannot be performed.

The resin composition of the present invention can maintain the flame retardancy class V-0 of UL-94 even without adding a halogen compound such as brominated epoxy resin or antimony oxide such as antimony trioxide as a flame retardant. From the viewpoint of environmental protection and improvement of the reliability of semiconductor devices such as high-temperature storage properties, a resin composition without adding a flame retardant is preferable. It has been found that conventionally, when a flame retardant is blended, the high-temperature storage characteristics are remarkably deteriorated, and there is a possibility that the performance of the semiconductor device may be lowered. According to the present invention, sufficient flame retardancy can be obtained by increasing the number of carbon atoms derived from the aromatic ring even without the flame retardant.

Since the resin composition of the present invention achieves the purpose of flame retardancy by increasing the number of aromatic rings in the molecule, it has the feature of being difficult to thermally decompose in air. Another characteristic of the cured product of the resin composition of the present invention is that the thermal decomposition initiation temperature is 280° C. or higher in the TG curve analysis (thermogravimetric analysis: thermogravimetric analysis) shown in FIG. 1 . Since the thermal decomposition start temperature is above 280°C, it can effectively improve the flame retardancy.

The method of measuring the thermal decomposition start temperature is: using TG/DTA220 produced by SEIKO Electronics Co., Ltd., in an air atmosphere, under the conditions of a temperature increase rate of 20°C/min and an air flow rate of 200ml/min, the cured resin combination is measured. (after curing at 175° C. for 4 hours, finely pulverize the cured product, and accurately weigh about 5 to 10 mg). As shown in FIG. 1 , the temperature at which rapid thermal decomposition starts when the temperature is raised is taken as the thermal decomposition start temperature. If the thermal decomposition start temperature is higher than 280° C., the flame retardancy in the UL-94 test is also good. On the other hand, if the thermal decomposition initiation temperature is lower than 280° C., the flame retardancy will decrease.

In addition, in the resin composition in which the amount W (weight %) of the inorganic filler contained in the entire resin composition is 88≤W≤94, in the TG curve analysis of the cured resin composition in the air atmosphere, at 500 ° C , The cured product residual rate A (weight %) after 1 hour is: W+[0.1×(100-W)]≤A, which can also effectively improve the flame retardancy. If the content of aromatic-derived carbon atoms is high, it will take a while for complete combustion, and after treatment at 500° C. for 1 hour, the carbides of the resin component cannot be completely combusted and remain. If the value of the residual ratio A of the cured product is less than W+[0.1×(100-W)], it burns rapidly, so the flame retardancy is low.

In the present invention, the measurement method of the residual rate A of cured product is: use TG/DTA220 produced by Seiko-Electronics Co., Ltd., in an air atmosphere, under the conditions of a heating rate of 20°C/min and an air flow rate of 200ml/min, and After heating up to 500°C at a heating rate of 20°C/min, and then keeping it at 500°C for 1 hour, the cured resin composition was measured (after 4 hours of post-curing at 175°C, the cured product was finely pulverized as The sample is accurately weighed about 5 ~ 10mg). Then calculate the remaining rate of cured product, divide the remaining amount with the sample, and express it in %.

In the resin composition of the present invention, in addition to components (A) to (D), silane dioxanes such as γ-glycidoxypropyltrimethoxysilane and γ-aminopropyltriethoxysilane may be added as needed. Colorants such as mixtures, carbon black and other colorants, low-stress components such as silicone oil and silicone rubber, natural waxes, synthetic waxes, polyethylene waxes, oxidized polyethylene waxes, higher fatty acids and their metal salts, or release agents such as paraffin waxes, antioxidants, etc. Various additives. Especially the additive silicone oil is very effective in reducing voids.

The resin composition of the present invention is obtained by mixing components (A) to (D) and other additives at room temperature with a mixer, kneading with a kneader such as a roll or an extruder, cooling, and pulverizing.

When sealing a semiconductor element with the resin composition of the present invention to manufacture a semiconductor device, conventional molding methods such as transfer molding, compression molding, and injection molding can be used for curing molding.

Examples of the present invention are shown below, but the present invention is not limited to them. The compounding unit is parts by weight. Example 1

After mixing the following components at room temperature using a mixer, kneading with twin rolls at 100°C, cooling and pulverizing to obtain a resin composition:

式(H-1)的酚醛树脂(来自芳香族的碳原子含量为100％)Epoxy resin (73% from aromatic carbon atom content) with formula (E-1) as main component: 5.0 parts by weight

Phenolic resins of formula (H-1) (100% from aromatic carbon atoms)

5.0 parts by weight

1,8-diazabicyclo(5,4,0)undecene-7 (hereinafter referred to as DBU)

0.2 parts by weight

Fused spherical silica (average particle size 15) 89 parts by weight

Epoxy silane coupling agent 0.3 parts by weight

Carbon black 0.2 parts by weight

Carnauba wax 0.3 parts by weight

The obtained resin composition was evaluated by the following method. The results are shown in Table 1. Evaluation method

·Thermal decomposition start temperature: The above-mentioned measurement method was used.

- The remaining rate of the cured product of the resin composition: The above-mentioned measuring method was used.

- Spiral flow: measured at a molding temperature of 175° C. using a mold conforming to EMMI-I-66.

·Flame retardancy: Made into a 1.6mm thick molded product, and subjected to a combustion test according to UL-94.

·High-temperature storage characteristics: 16pDIP with analog components mounted is molded, post-cured, and treated at 185°C for 1,000 hours. The resistance value between wiring lines after processing was measured, and the sealing material whose resistance value increased by 20% or more was regarded as defective. Expressed as the number of bad seals out of 15 seals.

·Solder resistance: Using a low-pressure transfer molding machine, under the conditions of molding temperature 175°C, pressure 70kg/cm ² , and curing time 2 minutes, it is molded into 80pQFP (seal size 14×20×2.7mm, chip size 9mm×9mm ), after 8 hours of post-curing at 175°C, the 6 seals were subjected to moisture absorption for 168 hours at 85°C and a relative humidity of 85%, and IR reflow treatment was performed at 235°C, and the sealing was observed with an ultrasonic flaw detector Cracks in parts, when there are n cracked seals, it is expressed as n/6.

Embodiment 2～6

According to the formulation of Table 1, the resin composition was obtained similarly to Example 1, and it evaluated similarly to Example 1. The results are shown in Table 1. Comparative example 1-6

According to the formulation of Table 2, the resin composition was obtained similarly to Example 1, and it evaluated similarly to Example 1. The results are shown in Table 2.

The epoxy resins used in Examples 2 to 5 or Comparative Examples 4 to 6, the structural formulas of the formula (E-2) and the formula (E-3), the phenolic resin, the formula (H-2) and the formula (H -4) Structural formulas to formula (H-6) and description of phenolic resin (H-3).

In addition, the aromatic carbon atom content of formula (E-2) was 72%, and the aromatic carbon atom content of (E-3) was 42%. The aromatic carbon atom content of formula (H-2) is 100%, the aromatic carbon atom content of formula (H-4) is 100%, and the phenolic hydroxyl equivalent of formula (H-5) is 98, from The aromatic carbon atom content is 100%, and the aromatic carbon atom content of the formula (H-6) is 50%. Phenolic resin (H-3) is a polycondensation product of heavy oil and formaldehyde and phenols in the presence of an acid catalyst. The softening point is 82°C, the hydroxyl equivalent is 145, and the ICI viscosity/150°C is 2.2 poise, about 95% carbon atoms from aromatics.

(a)/(b)=2/1 molten mixture...(E-2)

Table 1 Example 1 2 3 4 5 6 Epoxy resin (E-1) 5.0 4.8 5.0 5.3 3.2 Epoxy resin (E-2) 5.0 Curing agent (H-1) 5.0 3.2 Curing agent (H-2) 5.2 5.0 Curing agent (H-3) 5.0 Curing agent (H-4) 4.8 DBU 0.2 0.2 Triphenylphosphine 0.2 0.2 0.2 0.1 Fused spherical silica 89 89 89 89 89 93 Epoxy silane coupling agent 0.3 0.3 0.3 0.3 0.3 0.2 carbon black 0.2 0.2 0.2 0.2 0.2 0.2 carnauba wax 0.3 0.3 0.3 0.3 0.3 0.2 Combustion start temperature (°C) 330 320 333 321 317 311 Remaining amount after treatment at 500°C for 1 hour (%) 92.0 91.4 93.5 92.0 93.2 95.1 Spiral flow(cm) 101 88 89 83 110 42 Flame retardant (1.6mm) V-0 V-0 V-0 V-0 V-0 V-0 High temperature storage characteristics 0/15 0/15 0/15 0/15 0/15 0/15 Solder resistance 0/6 0/6 0/6 0/6 0/6 0/6

Table 2 comparative example 1 2 3 4 5 6 Epoxy resin (E-1) 9.5 2.2 4.0 6.4 5.0 Epoxy resin (E-3) 5.2 Curing agent (H-1) 9.0 2.1 4.0 4.8 Curing agent (H-5) 3.6 Curing agent (H-6) 5.0 Brominated bisphenol A type epoxy resin 1.0 Antimony trioxide 1.0 DBU 0.2 0.2 0.2 0.2 0.2 Triphenylphosphine 0.1 Fused spherical silica 80 95 89 89 89 89 Epoxy silane coupling agent 0.5 0.2 0.3 0.3 0.3 0.3 carbon black 0.5 0.2 0.2 0.2 0.2 0.2 carnauba wax 0.3 0.2 0.3 0.3 0.3 0.3 Combustion start temperature (°C) 314 Can't form 310 289 268 264 Remaining amount after treatment at 500°C for 1 hour (%) 83.2 - 90.3 90.0 91.0 89.7 Spiral flow(cm) 104 Can't form 103 89 91 77 Flame retardant (1.6mm) V-1 Can't form V-0 burn completely V-1 burn completely High temperature storage characteristics 0/15 Can't form 15/15 0/15 0/15 0/15 Solder resistance 6/6 Can't form 0/6 3/6 1/6 2/6

As can be seen from Table 1, the epoxy resin composition for encapsulating semiconductors of the present invention has excellent moldability and flame retardancy, low water absorption, and excellent solder resistance of semiconductor devices sealed with the composition.

Claims (5)

1. epoxy resin composition for encapsulating semiconductor, contain in this composition epoxy resin: (A) Resins, epoxy, wherein, in whole carbon atoms of Resins, epoxy, from the content of aromatic carbon atom more than 70%, (B) resol, wherein, in whole carbon atoms of resol, from the content of aromatic carbon atom more than 70%, and the phenolic hydroxyl group equivalent is 140～300, (C) curing catalyst and (D) mineral filler, and its addition W (weight %) in whole composition epoxy resins is 88≤W≤94; It is characterized in that during the TG curve of the composition epoxy resin that has solidified in air atmosphere resolved, burning beginning temperature was more than 280 ℃.

2. epoxy resin composition for encapsulating semiconductor, contain in this composition epoxy resin: (A) Resins, epoxy, wherein, in whole carbon atoms of Resins, epoxy, from the content of aromatic carbon atom more than 70%, (B) resol, wherein, in whole carbon atoms of resol, from the content of aromatic carbon atom more than 70%, and the phenolic hydroxyl group equivalent is 140～300, (C) curing catalyst and (D) mineral filler, and its addition W (weight %) in whole composition epoxy resins is 88≤W≤94; It is characterized in that during the TG curve of the composition epoxy resin that has solidified in air atmosphere resolved, the survival rate A (weight %) of cured article was W+[0.1 * (100-W)]≤A.

3. the epoxy resin composition for encapsulating semiconductor described in the claim 1 or 2, wherein, Resins, epoxy is the Resins, epoxy shown in Resins, epoxy shown in the general formula (1) or the general formula (2):

(R ₁～R ₄Be hydrogen atom, phenyl or methyl, can be identical or different)

(R ₁～R ₈Be hydrogen atom, methyl or the tertiary butyl, can be identical or different).

4. the epoxy resin composition for encapsulating semiconductor described in the claim 1 or 2, wherein, resol is the resin that resol shown in the resol shown in the general formula (3), the general formula (4) or the oil polycondensate that is mink cell focus and formaldehyde and phenols polycondensation form:

(n is a mean value, is the positive number more than 1)

(R ₁Be hydrogen atom or methyl, n is a mean value, is the positive number more than 1).

5. a semiconductor device is characterized in that, it is to use the epoxy resin composition for encapsulating semiconductor described in the claim 1,2,3 or 4 that semiconductor element encapsulation is formed.

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