JP2008184585A - Resin composition for sealing semiconductor and semiconductor device obtained using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for sealing semiconductors that exhibits high flowability, suppressed generation of wire sweep and the like on molding and excellent moldability even when inorganic filler is highly loaded, and the like. <P>SOLUTION: The resin composition for sealing semiconductors comprises a thermosetting resin, a curing agent and an inorganic filler, where the inorganic filler is mainly composed of an inorganic powder (A) shown below. (A) An inorganic powder comprising (a1) and (a2) below, where the weight ratio [(a1)/(a2)] is set within the range of 99/1-70/30. (a1) An inorganic powder having two maximum frequency values within the region of 2.0-100.0 μm in the volume frequency grain size distribution, where the two maximum frequency values are such that the ratio of the frequency value having the larger particle size to the frequency value having the smaller particle size is within the range from 4.0 to 9.0. (a2) An inorganic powder has one maximum frequency value within a region of at least 0.1 μm and less than 2.0 μm in the volume frequency grain size distribution. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin composition for encapsulating a semiconductor having excellent moldability that does not cause problems such as wire flow in a package during molding, and a semiconductor device using the same.

  Semiconductor elements such as transistors, ICs, and LSIs are usually resin-sealed by transfer molding using a thermosetting resin composition such as an epoxy resin composition to form a semiconductor device. Conventionally, various types of packages have been developed as this type of package.

  The epoxy resin composition is usually composed of an epoxy resin, a phenol resin, a curing accelerator, an inorganic filler, a mold release agent, a flame retardant, a coupling agent, and the like. Each raw material is mixed and dispersed by mixing and then melt-kneading using a heating kneader such as a single-screw kneader, twin-screw kneader, heating roll, continuous kneader, or batch kneader. .

  On the other hand, along with the downsizing, weight reduction, and high functionality of electrical equipment, the downsizing, thinning, and narrowing of semiconductor packages are accelerating, and as a result, the solder package heat resistance and moisture resistance of semiconductor packages are further improved. It has been demanded. For this reason, the content of the inorganic filler in the epoxy resin composition is increasing, and the increase in the content of the inorganic filler causes a decrease in fluidity during sealing molding. Molding defects such as flow and void generation are increased.

  For example, in a thin package such as a surface mount type, resin sealing is performed using a resin composition containing a large amount of an inorganic filler in order to improve solder heat resistance in a surface mount process. Due to this, there is a problem that defects during molding, that is, wire flow, void formation, lead pin deformation, die pad shift and the like are likely to occur. That is, as a result of using a resin composition in which the content of the inorganic filler is filled to the maximum for the purpose of suppressing moisture absorption of the package and improving the resin strength, the above-described problems occur. And when such a resin composition is used, fluidity | liquidity will fall remarkably and will cause the various problems on shaping | molding as stated above.

In order to solve such problems, it has been studied to make the shape of the inorganic filler close to a true sphere and improve the fluidity of the resin. Moreover, in order to ensure the favorable fluidity | liquidity at the time of shaping | molding, increasing the content of an inorganic filler, using a resin component with a lower viscosity is also examined. Furthermore, in the frequency particle size distribution, a resin composition using a spherical inorganic powder having a maximum value in a region of 20 to 70 μm, a region of 3.0 to 10 μm, and a region of 0.20 to 1.0 μm has been proposed ( Patent Document 1).
JP 2001-158614 A

  However, a method using an inorganic filler having a shape close to a true sphere or a resin component having a low viscosity is not sufficient in improving fluidity. Moreover, in the resin composition using the spherical inorganic powder having the specific frequency particle size distribution, it is difficult to say that the fluidity is still sufficient when molding a thin semiconductor package in recent years.

  The present invention has been made in view of such circumstances, and when forming a thin semiconductor package, it has high fluidity even in high filling with an inorganic filler, and the occurrence of wire flow during molding is suppressed, It is an object of the present invention to provide a semiconductor sealing resin composition having excellent moldability and a semiconductor device using the same.

In order to achieve the above object, the present invention provides a resin composition for encapsulating a semiconductor comprising a thermosetting resin, a curing agent and an inorganic filler, wherein the inorganic filler has the following inorganic powder ( The resin composition for semiconductor sealing which has A) as a main component is made into the 1st summary.
(A) An inorganic powder composed of the following (a1) and (a2), the ratio of which is set to a weight ratio of [(a1) / (a2)] = 99/1 to 70/30 Inorganic powder.
(A1) Inorganic powder having two maximum frequency values in the region of 2.0 to 100.0 μm in the volume frequency particle size distribution, and the frequency value on the smaller particle size side of the two maximum frequency values The ratio of the frequency value on the larger particle size side to 4.0 to 9.0 is an inorganic powder.
(A2) An inorganic powder having one maximum frequency value in a region of 0.1 μm or more and less than 2.0 μm in the volume frequency particle size distribution.

  And this invention makes the 2nd summary the semiconductor device formed by resin-sealing a semiconductor element using the said resin composition for semiconductor sealing.

  In order to achieve the above-mentioned object, the present inventors have repeated research centering on inorganic fillers that are greatly involved in fluidity among the compositions of thermosetting resin compositions used for sealing semiconductor devices, and particularly inorganic substances. An extensive study was conducted on the particle size distribution of the filler. In the course of the research, the inorganic powder having the particle size distribution shown in the above (a1) and the inorganic powder having the particle size distribution shown in the above (a2) are mixed at a specific ratio, and an inorganic powder ( It was recalled that A) was contained as the inorganic filler. This inorganic powder (A) is a powder containing a small amount of the inorganic powder shown in the above (a1) and having a small space ratio, and also contains an inorganic powder having a fine particle size as in the above (a2). It becomes an inorganic filler with a high filling rate and capable of high filling. That is, the inorganic powder with a fine particle size as in (a2) is usually added for the purpose of improving fluidity and reducing the viscosity. However, if it is added too much, the specific surface area increases. Will cause thickening. However, by adopting a particle size distribution design that increases the filling rate of the inorganic powder specified in (a1) above, it becomes possible to minimize the amount of addition of the inorganic powder (a2). It has been found that the fluidity of the inorganic filler is good in spite of high filling, the viscosity at the time of molding flow is reduced, and as a result, the generation of wire flow in the package at the time of molding is suppressed and the present invention has been reached. .

  As mentioned above, this invention is a resin composition for semiconductor sealing containing the inorganic filler which has the inorganic powder (A) which has the said specific particle size distribution as a main component. For this reason, even if content of the said inorganic filler is high content of the whole resin composition like the past, the fluidity | liquidity as a sealing material improves significantly and the outstanding moldability is obtained. Therefore, the semiconductor device obtained by using the resin composition for semiconductor encapsulation of the present invention is excellent in reliability because generation of wire flow in the package is suppressed during the sealing molding.

  When spherical fused silica is used as the inorganic filler, a material having even better fluidity can be obtained.

  The thermosetting resin composition that is the resin composition for semiconductor encapsulation of the present invention is not particularly limited, and various thermosetting resins conventionally used as sealing materials are used and cured. And a specific inorganic filler, and various additives. And the thermosetting resin composition which is a resin composition for semiconductor sealing is usually in the form of a powder or a tablet obtained by tableting this.

  In the resin composition for semiconductor encapsulation of the present invention, an epoxy resin is suitably used as the thermosetting resin. When an epoxy resin is used as the thermosetting resin, it is obtained using a phenol resin and a specific inorganic filler.

  The epoxy resin is not particularly limited, and various epoxy resins are used. For example, bisphenol A type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, triphenylmethane type epoxy resin and the like can be mentioned. These may be used alone or in combination of two or more. Among these epoxy resins, it is preferable from the viewpoint of reliability to use a biphenyl type epoxy resin or a low moisture absorption type epoxy resin in which a lower alkyl group is added to the phenyl ring. Such an epoxy resin preferably has an epoxy equivalent of 150 to 250 and a softening point or melting point of 50 to 130 ° C.

  The phenol resin used together with the epoxy resin has a function as a curing agent for the epoxy resin, and is not particularly limited. Monomers, oligomers, and polymers generally having two or more phenolic hydroxyl groups in one molecule. Say. Examples thereof include phenol novolak, cresol novolak, biphenyl type novolak, triphenylmethane type, naphthol novolak, phenol aralkyl resin, biphenyl aralkyl resin, and the like. These may be used alone or in combination of two or more. Among them, it is preferable from the viewpoint of reliability to use a low hygroscopic material such as a phenol aralkyl resin or a biphenyl aralkyl resin.

  It is preferable to mix | blend the mixture ratio of the said epoxy resin and a phenol resin so that the hydroxyl group equivalent in a phenol resin may be 0.5-2.0 equivalent per 1 equivalent of epoxy groups in an epoxy resin. More preferably, it is 0.8-1.2 equivalent.

  The specific inorganic filler used together with the epoxy resin and the phenol resin is an inorganic filler mainly composed of an inorganic powder (A) having a specific particle size distribution. When the inorganic powder (A) having the specific particle size distribution is a main component, the entire inorganic filler may be composed of only the inorganic powder (A) or other than the inorganic powder (A). This means that an inorganic filler may be used in combination.

  Examples of the inorganic filler other than the inorganic powder (A) include silica, alumina, aluminum nitride, talc, and calcium carbonate other than the inorganic powder (A). These may be used alone or in combination of two or more.

  When the inorganic filler other than the inorganic powder (A) is used in combination, the proportion of the inorganic filler other than the inorganic powder (A) is preferably set to 30% by weight or less, particularly preferably. 10% by weight or less.

The inorganic powder (A) having the specific particle size distribution is an inorganic powder composed of the following (a1) and (a2), and the ratio is [(a1) / (a2)] = 99 in weight ratio. / 1 to 70/30. Here, the “volume frequency particle size distribution” described below is obtained by dividing the target particle diameter range and displaying the amount (volume) of particles existing in each particle diameter section in%. Can be measured using a laser diffraction / scattering particle size distribution analyzer or the like. Then, as described below, by using the inorganic powder (A) obtained by mixing the inorganic powders (a1) and (a2) having different particle size distributions at the above ratio, the filling rate is increased and the fluidity is increased. As a result, wire flow and the like are suppressed, and excellent moldability is exhibited.
(A1) Inorganic powder having two maximum frequency values in the region of 2.0 to 100.0 μm in the volume frequency particle size distribution, and the frequency value on the smaller particle size side of the two maximum frequency values The ratio of the frequency value on the larger particle size side to 4.0 to 9.0 is an inorganic powder.
(A2) An inorganic powder having one maximum frequency value in a region of 0.1 μm or more and less than 2.0 μm in the volume frequency particle size distribution.

  That is, in the ratio of the above (a1) and (a2), if the ratio of (a1) is too small, the filling rate of the inorganic powder is decreased, the resin melt viscosity is increased, and the ratio of (a2) is increased. This is because the specific surface area increases and the melt viscosity particularly in the low shear rate region increases. Conversely, if the ratio of (a2) is too small, the high filling level required in the present invention cannot be achieved. In particular, it is preferable to set in the range of [(a1) / (a2)] = 95/5 to 80/20 (weight ratio) in that the effects of the present invention can be obtained more remarkably.

  Furthermore, regarding the inorganic powder defined in (a1) above, the ratio of the frequency value on the larger particle size side to the frequency value on the smaller particle size side of the two maximum frequency values in the volume frequency particle size distribution is: When it is in the range of 6 to 8, higher filling becomes possible, which is preferable.

  Such inorganic powder (A) is not particularly limited, and various conventionally known fillers are used. Examples thereof include silica powder such as fused silica powder and crystalline silica powder, alumina powder, talc and the like. These fillers may be used alone or in combination of two or more. These fillers can be used in any form such as crushed, spherical, or ground. Among them, it is preferable to use a spherical material, particularly a spherical fused silica powder.

And as an inorganic filler which has as a main component the inorganic powder (A) which has the said specific particle size distribution, it is especially preferable that the sphericity in the whole inorganic filler is 0.85 or more. Of course, the sphericity is more preferable as it approaches 1.0. The sphericity is a value represented by a so-called roundness, and this roundness is usually calculated as follows. That is, in the projection image a of the object to be measured for roundness, when the actual area is α and the perimeter of the projection image a is PM, the perimeter of the projection image a is the same. Assume a projected image b of a perfect circle having a PM of. Then, the area α ′ of the projected image b is calculated. As a result, the ratio (α / α ′) of the actual area α of the projected image a and the area α ′ of the projected image b indicates roundness, and this value (α / α ′) is expressed by the following equation: (α / Α ′) = (α · 4π) / [(PM)] ² = [π ² · (HD)] / [(PM)] ² [HD is true that is equal to the real area α of the projected image a The diameter of the circle, (HD) ² = (4α / π). ] Is calculated. Therefore, a roundness of 1.0 is a perfect circle, as is clear from this definition. In the present invention, the roundness of the inorganic filler is a value obtained by arbitrarily extracting a part from the inorganic filler to be measured and measuring by the above method. Say roundness.

  Further, as the inorganic filler mainly composed of the inorganic powder (A) having the above specific particle size distribution, it is preferable to use one having an average particle diameter of the whole inorganic filler in the range of 5 to 40 μm. It is preferable from the point of making. The average particle size can be measured, for example, with a laser diffraction / scattering particle size distribution analyzer.

  The content of the inorganic filler mainly composed of the inorganic powder (A) having the specific particle size distribution is preferably set in the range of 70 to 95% by weight of the entire epoxy resin composition. Especially preferably, it is the range of 80-92 weight%. That is, if the amount is less than 70% by weight, the solder resistance of the package tends to be lowered. Conversely, if the amount exceeds 95% by weight, the fluidity is lowered, and the wire flow in the package, die pad shift, and lead pin deformation frequently occur. This is because the tendency to do is seen.

  In addition, the epoxy resin composition that is a sealing material usually requires various additives in addition to the inorganic filler mainly composed of the epoxy resin, the phenol resin, and the inorganic powder (A) having a specific particle size distribution. Depending on the case, it is blended appropriately.

  Examples of the various additives include curing accelerators, silane coupling agents, mold release agents, flame retardants, flame retardant aids, ion trapping agents, low stress agents, pigments such as carbon black, and the like.

  Examples of the curing accelerator include various conventionally known curing accelerators. For example, triarylphosphines such as triphenylphosphine, imidazoles such as tetraphenylphosphonium / tetraphenylborate, 2-methylimidazole, 1,8 -Diazabicyclo (5,4,0) undecene-7 and the like. These may be used alone or in combination of two or more.

  The silane coupling agent is not particularly limited, and various silane coupling agents can be used. Among them, those having two or more alkoxy groups are preferably used. Specifically, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxy Examples thereof include silane, γ-mercaptopropylmethyldimethoxysilane, γ-anilinopropyltrimethoxysilane, and hexamethyldisilazane. These may be used alone or in combination of two or more.

  Examples of the releasing agent include compounds such as higher fatty acids, higher fatty acid esters, higher fatty acid calcium, and the like. For example, carnauba wax and polyethylene wax are used, and these are used alone or in combination of two or more.

  Examples of the flame retardant include novolak-type brominated epoxy resins and metal hydroxides, and examples of the flame retardant aid include diantimony trioxide and diantimony pentoxide. These may be used alone or in combination of two or more.

  As said ion trap agent, all the well-known compounds which have ion trap ability can be used, for example, hydrotalcites, bismuth hydroxide, etc. are used.

  Examples of the stress reducing agent include butadiene rubbers such as methyl acrylate-butadiene-styrene copolymer and methyl methacrylate-butadiene-styrene copolymer, and silicone compounds.

  The epoxy resin composition as the semiconductor sealing resin composition of the present invention can be produced, for example, as follows. That is, after mixing and mixing the above-mentioned epoxy resin, phenol resin and inorganic filler (A) having a specific particle size distribution as a main component, and other additives as necessary, a mixing roll machine, etc. The mixture can be melted and mixed in a kneading machine, cooled to room temperature, pulverized by a known means, and tableted as necessary.

  The sealing of the semiconductor element using such an epoxy resin composition is not particularly limited, and can be performed by a known molding method such as normal transfer molding.

  Next, examples will be described together with comparative examples.

  First, the following components were prepared prior to the examples.

〔Epoxy resin〕
Biphenyl type epoxy resin (manufactured by Yuka Shell Epoxy, YX-4000H, epoxy equivalent 194, melting point 106 ° C.)

[Phenolic resin]
Meiwa Kasei Co., Ltd., MEH7851SS (hydroxyl equivalent 203, softening point 69 ° C.)

[Curing accelerator]
TPP (triphenylphosphine), manufactured by Hokuko Chemical Co., Ltd.

〔Release agent〕
Carnauba wax

[Inorganic filler]
Spherical fused silica powders A to G having a particle size distribution shown in Table 1 below were prepared. Note that each of the above A to G is composed of two types of spherical fused silica powder, of which the larger one of the maximum frequency values in the volume frequency particle size distribution is (a1) and the smaller one is the smaller one. (A2). In addition, the silica powder corresponding to (a1) has two maximum frequency values [maximum frequency values (1) and (2) in the volume frequency particle size distribution. Of these, the maximum frequency value (1) indicates the larger particle size side. ] Have. Here, the particle size distribution (volume frequency, maximum frequency value, maximum frequency value particle size) and average particle size in Table 1 are measured using a laser diffraction scattering type particle size distribution measuring apparatus (LA910, manufactured by Horiba, Ltd.). did. In addition, (a1) and (a2) in the above A to G are different in particle size distribution, but use the same quality silica powder, so the weight ratio between (a1) and (a2) is the volume. It shows the same value as the frequency ratio.

[Examples 1-5, Comparative Examples 1-2]
The raw materials shown in Table 2 below were blended in the proportions shown in the same table, and melt kneaded at 110 ° C. for 10 minutes using a batch kneader (manufactured by Toyo Seiki Co., Ltd., Labo Plast Mill). Next, the melted product was cooled and then pulverized to produce a desired powdery epoxy resin composition.

  Using each obtained epoxy resin composition, melt viscosity was measured according to the following method. Moreover, the semiconductor device was manufactured using each said epoxy resin composition, and the deformation | transformation state of the gold wire at this time was measured and evaluated according to the following method. These results are shown in Table 3 below.

[Melt viscosity]
The viscosity of each epoxy resin composition was measured at a shear rate of 1.0 (1 / s) and 9.2 (1 / s) at 175 ° C. using a parallel plate rheometer (manufactured by Haake, Rheostress 1). It was measured.

[Gold wire deformation]
Each epoxy resin composition is tableted and tableted, and this is used for packaging under molding conditions of a molding temperature of 175 ° C. and a molding time of 90 seconds on a low-pressure transfer molding machine (automatic molding machine manufactured by TOWA, CPS-40L). Was sealed and post-cured at 175 ° C. for 5 hours to obtain a semiconductor device. This semiconductor device is a ball grid array (BGA) package (resin sealing portion size: 35 mm × 35 mm × thickness 1.2 mm), and the chip size is 7.5 mm × 7.5 mm. The gold wire has a gold wire diameter of 23 μm and an average gold wire length of 5 mm. And the deformation | transformation state of the gold wire was observed for this produced package using the soft X-ray analyzer, and the presence or absence of a deformation | transformation was investigated.

  From the above results, all of the examples had a low melt viscosity, and therefore the gold wire was not deformed and was excellent in moldability.

  On the other hand, the comparative product using the spherical fused silica powder having a particle size distribution deviating from the definition of the present invention has a high melt viscosity, and as a result, the wire wire is deformed and the moldability is poor. there were.

Claims (5)

A resin composition for encapsulating a semiconductor comprising a thermosetting resin, a curing agent, and an inorganic filler, wherein the inorganic filler has an inorganic powder (A) shown below as a main component. Semiconductor sealing resin composition.
(A) An inorganic powder composed of the following (a1) and (a2), the ratio of which is set to a weight ratio of [(a1) / (a2)] = 99/1 to 70/30 Inorganic powder.
(A1) Inorganic powder having two maximum frequency values in the region of 2.0 to 100.0 μm in the volume frequency particle size distribution, and the frequency value on the smaller particle size side of the two maximum frequency values The ratio of the frequency value on the larger particle size side to 4.0 to 9.0 is an inorganic powder.
(A2) An inorganic powder having one maximum frequency value in a region of 0.1 μm or more and less than 2.0 μm in the volume frequency particle size distribution.   The resin composition for semiconductor encapsulation according to claim 1, wherein the inorganic filler is spherical.   The semiconductor sealing resin composition according to claim 1, wherein the inorganic filler is spherical fused silica.   Content of the said inorganic filler is 70 to 95 weight% of the whole resin composition for semiconductor sealing, The resin composition for semiconductor sealing as described in any one of Claims 1-3.   The semiconductor device formed by resin-sealing a semiconductor element using the resin composition for semiconductor sealing as described in any one of Claims 1-4.