JP2017053861A - Method for evaluating fusibility of granular resin composition, and method for manufacturing resin-sealed semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for evaluating fusibility of a granular resin composition which excels in fusibility and fluidity, while preventing resin leakage, in manufacturing a semiconductor device formed by compression molding, and a method for manufacturing the semiconductor device.SOLUTION: A method for evaluating fusibility of a granular resin composition includes: fusing a granular resin composition by heating at a melting temperature or higher until the granular resin composition is hardened while maintaining its fused appearance; acquiring luminance information from a surface state of the granular resin composition fused by heating; and evaluating the fusibility of the granular resin composition on the basis of the luminance information. A method for manufacturing a resin-sealed semiconductor device includes: selecting, using the fusibility evaluation method, a granular resin composition having a skewness of 0 to less than 2.5 and kurtosis of 0 to less than 5 in a histogram; and using the selected granular resin composition, to seal a semiconductor device by compression molding.SELECTED DRAWING: None

Description

  The present invention relates to a method for evaluating the meltability of a granular resin composition and a method for producing a resin-encapsulated semiconductor device using the same.

  In recent years, with high-density mounting of electronic components on a printed wiring board, semiconductor devices have been changed from a pin insertion type package, which has been conventionally used, to a surface mounting type package. Surface-mount ICs, LSIs, and the like are thin and small packages with a high mounting density, and the volume occupied by the elements in the package has increased, and the thickness of the package has become very thin. In addition, the increase in the chip area and the increase in the number of pins have progressed due to the multi-functionality and large capacity of the elements, and further the increase in the number of pads has led to a reduction in pad pitch and a reduction in pad size, so-called narrow pad pitch. Progressing.

  However, since the pitch between the electrodes cannot be reduced as much as the semiconductor element on the substrate on which the semiconductor element is mounted, it is possible to increase the number of terminals by increasing the length of the wire drawn from the semiconductor element or by tying the wires. ing. However, when the wire becomes thin, the wire is easily flown by the resin injection pressure in the subsequent resin sealing step. This tendency is particularly remarkable in the side gate method.

  Therefore, a so-called compression molding method has come to be used as a method for resin-sealing electronic elements such as semiconductor chips (see Patent Documents 1 and 2). In this compression molding method, a granular resin composition is supplied so as to face an object to be sealed (for example, a substrate on which an electronic element such as a semiconductor chip is provided) held in a mold. Resin sealing is performed by compressing the sealing material and the granular resin composition.

  Thus, according to the compression molding method, since the molten granular resin flows in a direction substantially parallel to the main surface of the object to be sealed, the amount of flow can be reduced, and the object to be sealed by the flow of the resin Can be reduced. In particular, wire bonded wiring or the like is effective in reducing breakage due to resin flow.

JP 2008-279599 A JP 2011-153173 A

  However, the thickness of the electronic component package is thin, and the semiconductor element connected by a long and thin wire increases the risk of wire deformation, and for powder semiconductor encapsulation with better meltability and fluidity. There has been a demand for a resin composition.

  However, by improving the meltability and fluidity of the resin composition for encapsulating a granular semiconductor, the occurrence of wire deformation is suppressed, but when the meltability and fluidity of the resin composition for encapsulating a granular semiconductor are improved. Under the reduced pressure during the molding of the semiconductor device, there is a high possibility that a so-called “resin leakage” will occur due to the scattering of the heated and melted resin.

  Then, an object of this invention is to provide the meltability evaluation method of the granular resin composition which is excellent in meltability and fluidity | liquidity and can prevent resin leakage.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have determined the meltability index of the resin composition for encapsulating a granular semiconductor, and by defining the meltability within a specific range, The inventors have found that the reduction and the resin leakage are suppressed, and have completed the present invention.

  That is, the meltability evaluation method for a granular resin composition of the present invention is a method in which the granular resin composition is cured at a temperature equal to or higher than its melting temperature and while maintaining the melted appearance of the granular resin composition. It heat-melts, acquires brightness | luminance information from the surface state of the said granular resin composition after the said heat-melting, The meltability of the said granular resin composition is evaluated based on this brightness | luminance information, It is characterized by the above-mentioned.

  The method for producing a resin-encapsulated semiconductor device of the present invention uses the method for evaluating the meltability of the granular resin composition of the present invention. In the histogram, the skewness is 0 or more and less than 2.5, and the kurtosis. A granular resin composition having an A of 0 or more and less than 5 is selected, and a semiconductor element is sealed by compression molding using the selected granular resin composition.

Here, it is further preferable that the slope a between the mode value and the median value expressed by the following equation (A) obtained from the histogram is −0.75% or more and −0.15% or less.

a = (mode frequency (%) − median frequency (%)) / (mode luminance−median luminance) (A)

(In the formula, the mode luminance and the median luminance are values (median values) that are the middle when the luminance and luminance values are arranged in descending order from the most frequently occurring value (mode), respectively. The mode frequency (%) and the median frequency (%) are the relative values (%) of the appearance frequency in the mode, where the total number of frequencies of each brightness is 100%, (The relative value (%) of the appearance frequency in the median.)

  According to the meltability evaluation method of the granular resin composition of the present invention, the meltability and fluidity of the resin composition are set as desired characteristics, and the wire flow rate due to the molten resin is extremely low at the time of molding, and there is no resin leakage. Less sealing properties with excellent moldability can be evaluated.

  Moreover, according to the manufacturing method of the resin-encapsulated semiconductor device of the present invention, in the meltability evaluation method for the granular resin composition, sealing is performed using the granular resin composition having predetermined characteristics. Thus, a resin-encapsulated semiconductor device with good reliability can be obtained.

FIG. 6 is a diagram illustrating a histogram of luminance values according to the first embodiment. FIG. 10 is a diagram showing a histogram of luminance values in Example 2. It is the figure which showed the histogram of the luminance value of Example 3. 10 is a diagram showing a histogram of luminance values in Comparative Example 1. FIG. 10 is a diagram showing a histogram of luminance values in Comparative Example 2. FIG.

  Hereinafter, the present invention will be described in detail.

  First, the (A) component biphenyl type epoxy resin used in the present invention can be used without particular limitation as long as it is an epoxy resin having a biphenyl skeleton. The biphenyl skeleton in the present invention includes those obtained by hydrogenating at least one aromatic ring of biphenyl rings.

  For example, 4,4′-bis (2,3-epoxypropoxy) biphenyl or 4,4′-bis (2,3-epoxypropoxy) -3,3 ′, 5,5′-tetramethylbiphenyl is the main component. And epoxy resin obtained by reacting epichlorohydrin with a biphenol compound such as 4,4′-biphenol or 4,4 ′-(3,3 ′, 5,5′-tetramethyl) biphenol. It is done. Among them, 4,4′-bis (2,3-epoxypropoxy) -3,3 ′, 5,5′-tetramethylbiphenyl, 4,4′-dihydroxy-3,3 ′, 5,5′-tetra An epoxy resin mainly composed of glycidyl ether of methylbiphenyl is preferred.

  Specifically, YX-4000 (epoxy equivalent 185), YX-4000H (epoxy equivalent 193) manufactured by Mitsubishi Chemical Corporation as a biphenyl type epoxy resin, and Nippon Kayaku as a biphenyl type epoxy resin having an aralkyl skeleton at both ends. Examples thereof include NC-3000 (epoxy equivalent 273) and NC-3000H (epoxy equivalent 288), which are biphenyl type epoxy resins manufactured by Yakuhin.

  By adopting a biphenyl type epoxy resin, the resin composition for encapsulating a semiconductor can maintain the melt viscosity in the optimum range even when blended with a high content of spherical silica as the component (D) described later, and further has excellent heat resistance. Can be obtained.

  Next, the phenol resin of component (B) used in the present invention has two or more phenolic hydroxyl groups per molecule, and can cure the epoxy resin of component (A). As long as it is generally used as a sealing material for semiconductor elements, it is not particularly limited.

  Examples of the (B) component phenolic resin include phenol novolac resin, cresol novolac resin, aralkyl type phenol resin, naphthalene type phenol resin, cyclopentadiene type phenol resin, triphenolalkane type phenol resin and the like. it can. These may be used alone or in combination of two or more. Among these, from the viewpoints of fluid injection and flame retardancy, a nitrogen-containing phenol resin represented by the following general formula (1) is preferable.

（式中、Ｒ^１は次の一般式（１−１）又は（１−２）で表される基であり、

Ｒ^２は次の一般式（１−３）又は（１−４）で表される基であり、

これらＲ^１およびＲ^２は互いに同じ骨格の一価と二価の基であってもよいし、異なる骨格の一価と二価の基であってもよい。また、Ｒ^３及びＲ^４は、それぞれ、水素原子、アルキル基またはアルコキシル基であり、互いに同一であっても異なってもよい。また、ｎは１〜５の整数である。）

(In the formula, R ¹ is a group represented by the following general formula (1-1) or (1-2);

R ² is a group represented by the following general formula (1-3) or (1-4),

These R ¹ and R ² may be monovalent and divalent groups of the same skeleton, or may be monovalent and divalent groups of different skeletons. R ³ and R ⁴ are each a hydrogen atom, an alkyl group or an alkoxyl group, and may be the same as or different from each other. Moreover, n is an integer of 1-5. )

For example, when R ¹ is (1-1), R ² is (1-3), and R ³ and R ⁴ are both hydrogen atoms, the compound represented by the chemical formula (1) is in the presence of an acidic catalyst. , Imidazolidilinone, phenol, and formaldehyde can be synthesized as shown in the following reaction formula.

As the above substituent, from the viewpoint of easy availability of raw materials, R ¹ is preferably (1-1), R ² is preferably (1-3), and R ³ and R ⁴ are hydrogen atoms. Is preferred. Also, if R ^3, R ⁴ is an alkyl group, a methyl group, an ethyl group, a propyl group, a butyl group, preferably a methyl group. When R ³ and R ⁴ are alkoxy groups, methoxy group, ethoxy group, propoxy group, butoxy group and the like can be mentioned, and methoxy group is preferable. n is an integer of 1-5. When n is within this range, it is excellent in terms of the balance between flame retardancy and moldability.

  Moreover, a commercial item can be used for the compound represented by General formula (1). As a commercial item, TAM-005 etc. which are the nitrogen modified phenolic compounds by Showa Denko KK are mentioned.

  The content ratio of the (A) component epoxy resin and the (B) component phenol resin in the molding material of the present invention is such that the (A) component epoxy resin in the (A) component epoxy resin is one (B) component phenol resin. The phenolic hydroxyl group is preferably selected so as to be 0.5 or more and 1.6 or less, more preferably 0.6 or more and 1.4 or less. (A) If the number of phenolic hydroxyl groups in (B) phenol resin is 0.5 or more with respect to one epoxy group in epoxy resin, the glass transition temperature of the cured product will be good, while 1.6 or less If present, the reactivity becomes good, and a cured product having a sufficient crosslinking density and high strength can be obtained.

  Next, as the curing accelerator of the component (C), a curing accelerator used in an epoxy resin-phenol curing system can be used. For example, 1,8-diazabicyclo [5.4.0] undecene-7 (DBU), Tertiary amines such as triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, tris (dimethylaminomethyl) phenol, 2-heptadecylimidazole, 2-methylimidazole, 2-phenylimidazole, 2-phenyl- Imidazoles such as 4-methylimidazole and 2-phenyl-4-methyl-5-hydroxymethylimidazole, organic phosphines such as tributylphosphine, diphenylphosphine and triphenylphosphine, tetraphenylphosphonium tetraphenylborate, triphenylphosphine Tetraphenyl boron salts such as fins tetraphenylborate and the like. Among these, imidazoles are preferable from the viewpoint of good fluidity and moldability. For example, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-undecylimidazole, 2-heptadecylimidazole. 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole Dazolium trimellitate, 2,4-diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-s-triazine, 2,4-diamino-6- [2'-undecylimidazolyl- ( 1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-ethyl-4′-methylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6 -[2'-methylimidazolyl- (1 ')]-ethyl-s-triazine, 2-phenylimidazole isocyanuric acid adduct, 2-methylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenylimidazoline, 1-cyanoethyl-2-phenyl-4,5-di (2-sia Ethoxy) methyl imidazole, 1-dodecyl-2-methyl-3-benzyl-imidazolium chloride, mention may be made of 1-benzyl-2-phenylimidazole hydrochloride, and 1-benzyl-2-phenyl imidazolium trimellitate, and the like. These imidazoles can be used alone or in admixture of two or more.

  The blending amount of the (C) component curing accelerator is usually 3.0 to 10.0 with respect to 100 parts by mass of the total amount of the (A) component biphenyl type epoxy resin and the (B) component phenol resin. It is selected in the range of about mass parts, preferably 4.0-9.0 mass parts, more preferably 5.0-8.0 mass parts.

  Next, the spherical silica as the component (D) in the present invention may be spherical silica as an inorganic filler blended in the epoxy resin. The blending ratio of the spherical silica of component (D) in the total resin composition needs to be 80% by mass to 95% by mass, and preferably 85% by mass to 93% by mass. When the blending ratio of the spherical silica is less than 80% by mass of the entire resin composition, the linear expansion coefficient increases and the dimensional accuracy, moisture resistance, mechanical strength, etc. of the molded product decrease. On the other hand, if it exceeds 95% by mass, the melt viscosity will increase and the fluidity will decrease, or the moldability will decrease, making practical use difficult.

  The spherical silica of component (D) in the present invention is (D1) spherical silica having a particle size of less than 5 μm, (D2) spherical silica having a particle size of 5 μm or more and less than 50 μm, and (D3) spherical silica having a particle size of 50 μm or more. Three kinds of particle size ranges are contained, and these spherical silicas are used in a predetermined proportion in the resin composition.

  That is, (D) the above-mentioned blending ratio of the spherical silica as a whole is composed of 15 to 30% by mass of (D1) spherical silica having a particle size of less than 5 μm and (D2) particle size of 5 μm or more in the resin composition. 55 to 80% by mass of spherical silica having a particle size of less than 50 μm, and (D3) 5 to 20% by mass of spherical silica having a particle size of 50 μm or more. Examples of the spherical silica mixed with particles having such a particle size range include FB-940, FB-875, FB-105 (trade name, manufactured by Denki Kagaku Kogyo Co., Ltd.), MSR8030 (Tatsumori Co., Ltd.). Company name, product name) and the like. Moreover, as long as the said mixture ratio is satisfy | filled, 2 or more types of said commercial item may be mixed, or the spherical silica which has a single particle size may be mixed.

  (D) When the blending ratio by the particle size of the spherical silica is in the above range, the resin composition for encapsulating a granular semiconductor exhibits good meltability, and such a resin composition for encapsulating a granular semiconductor is used. Thus, it is possible to obtain a semiconductor device in which occurrence of problems such as wire flow and resin leakage is suppressed.

  (D1) When spherical silica having a particle size of less than 5 μm is less than 15% by mass and (D3) spherical silica having a particle size of 50 μm or more is contained in an amount of more than 20% by mass, the granular resin composition is heated and melted The histogram of the luminance values obtained from the digital image of the molten surface of the powder tends to increase the skewness and kurtosis, and the meltability of the granular resin composition is too high, and when it is fed into the lower mold cavity, This is not preferable because the resin melted by heating under reduced pressure is likely to cause so-called “resin leakage”.

  Further, when (D1) the spherical silica having a particle diameter of less than 5 μm is more than 30% by mass and (D3) the spherical silica having a particle diameter of 50 μm or more is less than 5% by mass, the histogram of the luminance value has a skewness. It tends to be large and the kurtosis tends to be small, and the flowability of the wire tends to deteriorate because the meltability of the resin composition for encapsulating a granular semiconductor is low.

  Furthermore, the ratio {content of (D1) / content of (D2)} of (D1) spherical silica having a particle size of less than 5 μm and (D2) spherical silica having a particle size of 5 μm or more and less than 50 μm is 0.15. It is preferably between ˜0.50. When {content of (D1) / content of (D2)} is smaller than 0.15, the histogram of the luminance value tends to increase the skewness and kurtosis, and the meltability of the granular resin composition. Is low and the wire flowability tends to deteriorate. Further, when {content of (D1) / content of (D2)} is larger than 0.50, the histogram of the luminance value tends to have high skewness and low kurtosis, and the granular resin composition This is not preferable because the melting property of the product is high, and so-called “resin leakage” is likely to occur when the resin melted by heating and melting is supplied when it is supplied into the cavity of the lower mold or under reduced pressure.

  The particle diameter of the spherical silica as the component (D) is determined by a laser diffraction / scattering method. For example, a laser diffraction / scattering particle size distribution analyzer (trade name: LA-920, manufactured by Horiba, Ltd.) Can be obtained.

  In addition, in the resin composition for encapsulating a granular semiconductor of the present invention, in addition to the above-described components, a coupling agent and a composition that are generally blended in this type of composition as long as the effects of the present invention are not impaired. Release agents such as wax, natural wax, higher fatty acids, metal salts of higher fatty acids, colorants such as carbon black and cobalt blue, modifiers such as silicone oil and silicone rubber, hydrotalcites, ion scavengers, etc. An additive component can be mix | blended.

  As the coupling agent, an epoxy silane, amino silane, ureido silane, vinyl silane, alkyl silane, organic titanate, aluminum alcoholate, or the like is used. These can be used alone or in admixture of two or more. From the viewpoints of flame retardancy and curability, aminosilane coupling agents are preferable, and γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ- Aminopropylmethyldiethoxysilane and the like are preferable.

  The compounding amount of the additive component is about 0.01 to 3% by mass, preferably about 0.05 to 1% by mass, respectively, in the semiconductor sealing resin composition.

  In preparing the resin composition for encapsulating a granular semiconductor of the present invention, (A) biphenyl type epoxy resin, (B) phenol resin, (C) curing accelerator, (D) spherical silica, and The various additive components blended as necessary are mixed thoroughly by a mixer, etc., then heated and mixed with a hot roll, a kneader, etc., then cooled and solidified, and pulverized to an appropriate size. The crushed material is sieved and classified.

  The method for pulverizing the resin composition for encapsulating a granular semiconductor of the present invention is not particularly limited, and a general pulverizer can be used. A cutting mill, a ball mill, a cyclone mill, a hammer mill, a vibration mill, a cutter mill, and a grinder mill are preferable, and a speed mill is more preferable.

  Furthermore, you may provide the classification process which adjusts the ground material of the resin composition for semiconductor sealing obtained by the said grinding | pulverization to the particle aggregate which has a predetermined particle size distribution by sieve classification and air classification. For example, when classification is performed using a sieve of about 7 to 500 mesh, it can be applied favorably to the resin-encapsulated semiconductor device of the present invention.

  Next, the evaluation method of the meltability of the granular semiconductor encapsulating resin composition of the present invention will be described.

  First, the granular resin composition is put in a predetermined container such as an aluminum cup and heated and melted in an oven. Although heating temperature will not be specifically limited if it is more than the temperature which a granular resin composition fuse | melts, 130 to 180 degreeC is preferable.

  Moreover, it is preferable to carry out heating time until the cured resin composition is further cured while maintaining the melted appearance of the granular resin composition. Specifically, in the case of a resin composition for encapsulating a granular semiconductor containing an epoxy resin as a main component, it is preferably from 3 minutes to 10 minutes.

  Next, after melting the granular resin composition by heating, luminance information is acquired from the surface state. For example, the melt surface may be imaged to obtain a digital image, and luminance information may be obtained based on the digital image.

  Next, the measurement target portion of the captured image is divided into a plurality of small sections, luminance information of each section is extracted, and a luminance histogram is obtained based on the luminance information. In the luminance histogram, the horizontal axis represents the luminance, and the vertical axis represents the appearance frequency of the luminance. As will be described later, the luminance is divided into 256 gradation levels from 0 to 255. The frequency on the vertical axis represents the appearance frequency of the luminance when the measurement target part is divided into a plurality of small sections and the total number of the small sections is the number of samples. As will be described later, when image processing is performed by digital processing, each of the small sections corresponds to one pixel.

  The image pickup means is not particularly limited, but an image pickup device including a CMOS image sensor (Complementary Metal Oxide Semiconductor Image Sensor) or a CCD image sensor (Charge Coupled Device Image Sensor) as the image pickup element is preferable. Such an imaging device is not particularly limited as long as it can obtain a digital image, such as a digital camera, a digital video camera, a digital microscope, or a digital scanner.

  The illumination at the time of imaging is not particularly limited, but it is preferable to set the “mode luminance” in the appearance frequency of the obtained luminance data to be between 20 and 60, more preferably between 30 and 50. . By setting the mode luminance value within this range, accurate skewness and kurtosis can be obtained.

  Further, if the illumination angle from the illumination light source is only in one direction, an error may occur due to the shadow of the convex portion. Therefore, it is preferable to eliminate the influence of the shadow by combining epi-illumination or a plurality of illumination means.

  The distance between the imaging means and the surface to be measured varies depending on the focal length and accuracy of the lens used, but is preferably 2 to 50 cm, particularly preferably 5 to 20 cm.

  The determination target portion of the obtained image is divided into minute sections, and a histogram is obtained from the luminance data of each small section. Here, the pixel size is preferably set to 100 dpi or more, more preferably 250 dpi or more. When the pixel size is coarse, the luminance is averaged between the pixels, so that the distribution of the melted state, in particular, the kurtosis and the skewness tend not to be reflected in the histogram. Since it is subdivided, the kurtosis and the skewness tend to increase and the calculation load tends to increase.

  In general, the pixel size is preferably set to about one-fifth of the particle size of the granular resin composition, so that the histogram can be used to properly grasp the molten state of the granular resin composition. Can do.

On the other hand, is preferably an area to be observed 5 to 50 cm ^2, more preferably from 10 to 30 cm ^2. If the observation area is small, deviation due to location tends to be picked up, and it is difficult to obtain data with good reproducibility. On the other hand, if the observation area is large, the amount of data tends to increase and it takes time for analysis.

  When the histogram obtained from the luminance information of the measurement target portion divided into a plurality of small sections is regarded as a probability distribution, the shape feature can be described as a first to fourth moment around the average. In the present invention, the calculated moment value can be grasped as an image feature amount reflecting the molten state of the granular resin composition.

  Each of the moments from the first order to the fourth order is “mode” and “average value”, “dispersion”, “distortion”, and “kurtosis”. In general, the greater the difference between the mode value and the average value, the greater the values of “dispersion”, “distortion” and “kurtosis”.

  Generally, the histogram of the molten state of the resin composition for encapsulating a granular semiconductor is displayed in black on the shadow side (brightness of 0) on the left side of the mode, where the resin surface is melted and glossy. Is done. This region has a large luminance frequency value and a steep distribution width.

  On the other hand, the highlight side on the right side of the mode value (luminance is 255) is insufficiently melted or wetted, the surface is close to a satin finish, and the light is irregularly reflected. Displayed in the system. This area has a shape in which the frequency value of the detected luminance is small, the width of the luminance is wide, and the tail is long in the right direction.

  For example, in a granular resin composition having good meltability (for example, FIG. 2), the surface of the resin composition is melted, and the ratio of the shadow side which is a glossy portion increases, so that the shape of the distribution is At the same time as the convergence to the mode value, the detected luminance range is widened, the slope of the frequency value is large, and the slope from the mode value to the median value is particularly steep.

  On the other hand, in the granular resin composition having poor meltability (for example, FIG. 5), the slope of the frequency value becomes gentler than that of the fine resin composition having good meltability, and the detected luminance is reduced. The range also tends to narrow.

  The skewness, which is a third moment, is an index indicating the asymmetry of the distribution and is defined by the following mathematical formula (B). This skewness is a scale indicating the degree to which the frequency values are not distributed symmetrically around the average in the histogram.

  From the above definition, if the frequency value is symmetric about the average, the skewness is 0, and in a distribution with a long skirt extending to the right and biased to the left, the skewness increases in the positive direction (positive) On the contrary, in a distribution that has a long skirt extending far to the left and biased to the right, the skewness increases in the negative direction (negative asymmetric distribution).

  As a result of the study by the present inventors, the granular resin composition generally exhibits a positive asymmetric distribution, and in the granular resin composition having good meltability and fluidity, the degree of distortion increases in the positive direction and melts. In a difficult granular resin composition, the degree of distortion is small.

  In a granular resin composition with good meltability (for example, FIG. 2), the detected luminance value has a relatively wide range and converges to the mode value located on the shadow side. Larger value.

  On the other hand, in the granular resin composition (for example, FIG. 5) inferior in meltability, it has a relatively narrow range, the mode value is also a relatively low value, and the mode value goes from the mode value to the highlight side. Since the inclination becomes gentle, the skewness becomes a small value. Here, in the case of a granular resin composition with particularly inferior meltability, the mode value is low and the slope of the frequency value is gradual as in the above, but the detected luminance range is narrow. Therefore, the skewness may take a large value.

  In the present invention, the skewness obtained from the histogram is preferably 0 or more and 2.5 or less, and more preferably 1 or more and 2 or less. If this distortion is less than 0, the meltability of the granular resin composition tends to be low and the wire flowability tends to deteriorate, and if it is greater than 2.5, the meltability of the granular resin composition is high, and the inside of the lower mold cavity It is not preferable since the resin melted by heating and splattering at the time of supply to the container, or the so-called “resin leakage” is likely to occur.

  The value of the kurtosis, which is a fourth-order moment, is an index representing the degree of kurtosis of the frequency distribution, and is defined by the following mathematical formula (C). If the frequency value is a normal distribution, the value is 0, When the concentration is high and sharper than the normal distribution, the value is positive. When the tail is wide and flatter than the normal distribution, the value is negative.

  As a result of the study by the present inventors, generally a granular resin composition optimal for the compression molding method shows a positive value.

  In a granular resin composition with good meltability (for example, FIG. 2), the detected luminance value has a relatively wide range and converges to the mode value, so the kurtosis is a large value.

  On the other hand, in the granular resin composition (for example, FIG. 5) inferior in meltability, the kurtosis is a small value because it has a relatively narrow range and the mode value is also a relatively low value.

  In the present invention, the kurtosis obtained from the histogram is preferably 0 or more and 5 or less, more preferably 1 or more and 4.5 or less. If the kurtosis is less than 0, the meltability of the granular resin composition is low and the wire flowability is deteriorated. If the kurtosis is greater than 5, the meltability of the granular resin composition is high. This is not preferable because a so-called “resin leakage” may occur, which is likely to occur when the resin melted by heating and splattering during supply or under reduced pressure.

  Further, as a method of evaluating the melted state from the obtained histogram shape, it can be determined by the shadow side inclination of the frequency value.

For example, the slope a between the mode value and the median value represented by the following formula (A) is effective as an index of the meltability and fluidity of the granular resin composition that is optimal for the compression molding method.

a = (mode frequency (%) − median frequency (%)) / (mode luminance−median luminance) (A)

(In the formula, the mode luminance and the median luminance are values (median values) that are the middle when the luminance and luminance values are arranged in descending order from the most frequently occurring value (mode), respectively. The mode frequency (%) and the median frequency (%) are the relative values (%) of the appearance frequency in the mode, where the total number of frequencies of each brightness is 100%, (The relative value (%) of the appearance frequency in the median.)

  In the present invention, the slope a between the mode value and the median value obtained by the equation (A) is preferably −0.75% or more and −0.1% or less. When this inclination a is less than -0.75%, the meltability of the granular resin composition is high, and when being supplied into the cavity of the lower mold, the resin that has been heat-melted is scattered under reduced pressure, so-called “Resin leakage” is likely to occur, and if it exceeds −0.1%, the meltability of the powdered resin composition tends to be low and the wire flowability tends to deteriorate, such being undesirable.

  Next, a resin-encapsulated semiconductor device obtained by using the epoxy resin composition for encapsulating a granular semiconductor of the present invention will be described.

  In the resin-encapsulated semiconductor device of the present invention, first, after supplying a substrate on which a semiconductor component is mounted on the upper mold, the resin composition for encapsulating a granular semiconductor of the present invention is supplied into the cavity of the lower mold, By clamping the upper and lower molds with a required clamping pressure, the semiconductor component is immersed in the powdered molding material heated and melted in the lower mold cavity. Next, the resin melted by heating in the lower mold cavity is pressed by the bottom member of the cavity, and under a reduced pressure, the required resin pressure is applied and the electronic component is compression molded to perform resin sealing.

  The molding conditions are preferably a molding temperature of 120 to 200 ° C. and a molding pressure of 2 to 20 MPa. The resin-encapsulated semiconductor device of the present invention is obtained by sealing by compression molding under such molding conditions.

  In addition, the kind of semiconductor chip sealed with the resin composition for semiconductor sealing at this time is not particularly limited, but the thickness of the semiconductor device after resin sealing is 0.2 to 1.5 mm. Such a thing is preferable.

  Thus, by molding by a compression molding method using the resin composition for semiconductor encapsulation of the present invention, it is possible to obtain a resin-encapsulated semiconductor device with small warpage and less wire flow.

  EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples at all.

Example 1
[Spherical silica]
Five types of spherical silica powders a to e in which spherical silicas having different particle size distributions were mixed were prepared, and the particle size distribution of these spherical silica powders was measured using a laser diffraction particle size distribution measuring apparatus (SALD-manufactured by Shimadzu Corporation). 2D), and (D1) particles having a particle diameter of less than 5 μm, (D2) particles having a particle diameter of 5 μm or more and 50 μm or less, and (D3) a content ratio of particles having a particle diameter of more than 50 μm on a mass basis. The results are shown in Table 1. The spherical silica prepared was spherical silica a (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name: FB-105FC; median diameter 16 μm), spherical silica b (manufactured by Tatsumori Co., Ltd., trade name: MSR-8030); Median diameter 14 μm), spherical silica c (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name: FB-875FC; median diameter 20 μm), spherical silica d (manufactured by Micron Corporation, trade name: S-140; median diameter 31 μm) , Spherical silica e (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name: FB-560; median diameter 17 μm).

  (A) 5.1 parts by mass of YX-4000HK (Mitsubishi Chemical Corporation, trade name; epoxy equivalent 193) as a biphenyl type epoxy resin, TAM-005 (trade name; manufactured by Showa Denko KK, trade name; hydroxyl group) as a phenol resin Equivalent 148) 3.9 parts by mass, (C) 0.66 parts by mass of 2-phenyl-4-hydroxymethyl-5-methylimidazole 2P4MHZ (trade name, manufactured by Shikoku Kasei Co., Ltd.) as a curing accelerator, (D) spherical 90 parts by mass of inorganic filler a as silica, 0.3 parts by mass of silane coupling agent 3-phenylaminopropyltrimethoxysilane (manufactured by Toray Industries, Inc., trade name: Z-6883), carbon black (Mitsubishi Chemical) Product name: MA-100) 0.25 parts by mass and carnauba wax 0.05 parts by mass mixed at room temperature And then heated and kneaded at 120 ° C.. After cooling, the mixture was pulverized using a speed mill, and then passed through a sieve to obtain a resin composition for encapsulating a granular semiconductor having a particle size of 0.2 to 2.0 mm.

(Example 2)
(D) A granular semiconductor encapsulating resin composition was obtained in the same manner as in Example 1 except that 90 parts by mass of the inorganic filler b was used as the spherical silica.

(Example 3)
(D) A granular semiconductor sealing resin composition was obtained in the same manner as in Example 1 except that 90 parts by mass of the inorganic filler c was used as the spherical silica. The results determined based on the following property evaluation criteria are shown in Table 1.

(Comparative Example 1)
(D) A granular semiconductor encapsulating resin composition was obtained in the same manner as in Example 1 except that 90 parts by mass of the inorganic filler d was used as the spherical silica. The results determined based on the following property evaluation criteria are shown in Table 1.

(Comparative Example 2)
(D) A granular semiconductor sealing resin composition was obtained in the same manner as in Example 1 except that 90 parts by mass of the inorganic filler e was used as the spherical silica. The results determined based on the following property evaluation criteria are shown in Table 1.

(Test example)
About the resin composition for granular semiconductor sealing obtained in Examples 1-3 and Comparative Examples 1-2, the composition is represented on a mass basis, and further, each characteristic of meltability, moldability, resin leakage, and wire flow The results are shown in Table 2 together with the results.

(Judgment criteria for characteristic evaluation)
[Fusibility]
5 g of the epoxy resin composition for encapsulating a granular semiconductor is put in an aluminum cup having a diameter of 50 mm, heated and melted in an oven at 175 ° C. for 10 minutes, and then the center diameter of the melted resin composition is about 42 mm (1 + 2/3 inch). ) At a resolution of 300 dpi to obtain luminance information of a circle having a diameter of 500 pixels.

By calculation processing, skewness, kurtosis, and the slope a between the mode value and the median value obtained by the following equation (A) were obtained.

a = (mode frequency (%) − median frequency (%)) / (mode luminance−median luminance) (A)

[Formability]
FBGA (50 mm x 50 mm x 0.54 mm) was compression-molded at 175 ° C for 2 minutes using an epoxy resin composition for encapsulating powdered semiconductors, and observed for the formation of "nests" on the surface of the molded product. Evaluation was made according to the following criteria.
○: No appearance abnormality (void or nest) ×: There is appearance abnormality (void or nest)

[Resin leakage]
FBGA (50 mm x 50 mm x 0.54 mm) was compression-molded at 175 ° C for 2 minutes using an epoxy resin composition for encapsulating powdered semiconductors, and resin leakage (scattering) to the periphery of the mold was observed. And evaluated according to the following criteria.
○: No resin leakage ×: Resin leakage

[Wire flow rate]
After sealing the FBGA, the deformation of the wire was observed with an X-ray inspection apparatus (manufactured by Pony Industry Co., Ltd.), the wire flow rate of the maximum deformed portion was measured, and evaluated according to the following criteria.
○: Less than 3% ×: 3% or more

  From the above, the epoxy resin composition for encapsulating a granular semiconductor of the present invention has a meltability and fluidity by making the kurtosis and skewness of the histogram of the surface state when melted within a predetermined range. It was found that the range was good, and during molding, the flow rate of the wire due to the molten resin was extremely low, the resin leakage was small, and the moldability was excellent.

Claims (8)

The powdered resin composition is heated and melted until it is cured at a temperature equal to or higher than the melting temperature and the powdered resin composition is cured while maintaining the melted appearance.
Obtaining luminance information from the surface state of the granular resin composition after the heating and melting,
A meltability evaluation method for a granular resin composition, wherein the meltability of the powdery resin composition is evaluated based on the luminance information.   2. The method for evaluating the meltability of a granular resin composition according to claim 1, wherein in the heating and melting, the granular resin composition is heated and melted at 130 ° C. or higher and 180 ° C. or lower for 3 minutes or longer and 10 minutes or shorter. .   As the luminance information, the measurement target portion of the digital image obtained by imaging the surface state of the granular resin composition is divided into a plurality of small sections, and the luminance information of each divided section is extracted, and the luminance information 3. A method for evaluating the meltability of a granular resin composition according to claim 1 or 2, wherein a luminance histogram is obtained based on the method.   4. The meltability evaluation of the granular resin composition according to claim 3, wherein the histogram is considered to be based on a probability distribution, and mode values and average values, dispersion, skewness, and kurtosis in the histogram are obtained. Method.   The method for evaluating the meltability of a granular resin composition according to any one of claims 1 to 4, wherein the luminance information is obtained by dividing the luminance into 256 gradation levels.   Using the meltability evaluation method for a granular resin composition according to any one of claims 3 to 5, in the histogram, the skewness is 0 or more and less than 2.5, and the kurtosis is 0 or more and less than 5. A method for producing a resin-encapsulated semiconductor device, comprising: selecting a certain granular resin composition, and sealing the semiconductor element by compression molding using the selected granular resin composition. In the granular resin composition, the slope a between the mode and the median represented by the following formula (A) obtained from the histogram is −0.75% or more and −0.15% or less. A method for manufacturing a resin-encapsulated semiconductor device according to claim 6.

a = (mode frequency (%) − median frequency (%)) / (mode luminance−median luminance) (A)

(In the formula, the mode luminance and the median luminance are values (median values) that are the middle when the luminance and luminance values are arranged in descending order from the most frequently occurring value (mode), respectively. The mode frequency (%) and the median frequency (%) are the relative values (%) of the appearance frequency in the mode, where the total number of frequencies of each brightness is 100%, (The relative value (%) of the appearance frequency in the median.)   The granular resin composition is a resin composition for encapsulating a granular semiconductor comprising (A) a biphenyl type epoxy resin, (B) a phenol resin, (C) a curing accelerator and (D) spherical silica as essential components. In addition, (D) the spherical silica is contained in the resin composition in an amount of 80% by mass or more and less than 95% by mass, and the breakdown of the content is (D1) a spherical silica having a particle size of less than 5 μm is 15 to 30% by mass, (D2) 55-80% by mass of spherical silica having a particle size of 5 μm or more and less than 50 μm, (D3) 5-20% by mass of spherical silica having a particle size of 50 μm or more, and (D1) particle size Ratio (content of (D1) / content of (D2)) of spherical silica having a particle diameter of less than 5 μm and (D2) spherical silica having a particle diameter of 5 μm or more and less than 50 μm is 0.15 to 0.50. The resin-sealed mold according to claim 6 or 7. Method of manufacturing a conductor arrangement.

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