Method for measuring silica powders, and silica powders and method for manufacturing the same

Abstract

To provide a method for measuring silica powders which can accurately measure the content rate of hollow silica particles, and silica powders less containing hollow silica particles and a method for manufacturing the same.SOLUTION: The method for measuring silica powders according to the present invention includes: a preparation step of preparing a silica-containing liquid by mixing silica powders with a liquid with a refractive index different from that of the silica powders by at least 0.03; an arrangement step of arranging the silica-containing liquid in a film pattern and obtaining a silica liquid film; and an observation step of observing the silica liquid film.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for measuring silica powder, as well as silica powder and a method for producing the same.

Background Art

[0002] Silica powder is used in various applications such as semiconductor parts, adhesives, films, and cosmetics. For example, in semiconductor parts, from the viewpoints of electrical insulation and low thermal expansion, it is added to resins for encapsulants such as epoxy resins, acrylic resins, and silicone resins as a filler for the encapsulant. In such a filler, silica powder composed of spherical silica particles may be used in order to improve the filling rate of the silica powder in the encapsulant.

[0003] By the way, as an example of the use of an encapsulant used for semiconductor parts and the like, its surface is ground, and a photoresist thin layer and wiring are sequentially laminated on the ground surface (see Patent Document 1). However, when there are hollow silica particles containing air bubbles in the silica powder, deep depressions due to the cavities of the hollow silica particles may occur on the ground surface of the encapsulant and further on the surface of the photoresist thin layer laminated thereon. In such a depressed portion of the photoresist thin layer, wiring defects such as disconnection may occur during the formation of the wiring, and as a result, a decrease in yield or a decrease in long-term reliability may occur in the semiconductor part. Therefore, there is a demand for providing silica powder having as little content of hollow silica particles as possible. Therefore, an inspection is carried out on the produced silica powder to determine how much hollow silica particles are contained therein.

[0004] As a method for inspecting hollow silica present in such silica powder, a resin kneading method has been conventionally known. In this method, first, the silica powder to be inspected is mixed and cured with a curable resin (for example, an epoxy resin), then the resin surface is ground smoothly, and the ground surface is observed with a microscope. Then, the depressions generated on the ground surface are judged as voids due to hollow silica particles, and the number of hollow silica particles is measured.

[0005] However, in the resin kneading method, including the curing time of the curable resin, it takes more than one day. In addition, among the depressions on the ground surface, there are also voids caused by the incorporation of air (bubbles) during resin curing, and there are cases where it is difficult to distinguish between voids due to hollow silica particles and voids due to bubbles. Therefore, this method may lack accuracy.

[0006] On the other hand, there has been proposed a method of detecting hollow inorganic fillers by dispersing inorganic fillers in a liquid and using an image analysis particle size distribution meter, where the ratio of the refractive index of the liquid to the refractive index of the inorganic filler is 0.98 to 1.02 (see Patent Document 2). In this method, the difference in refractive index between non-hollow inorganic fillers (solid inorganic fillers) and hollow inorganic fillers is utilized to confirm hollow inorganic fillers in the liquid.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, in this method, although the presence of hollow inorganic fillers can be confirmed, solid inorganic fillers cannot be visually recognized, so the content ratio of hollow inorganic fillers in the entire inorganic filler powder cannot be confirmed. Therefore, based on the content ratio, it is impossible to evaluate whether the inorganic filler powder is suitable for semiconductor components such as sealing material fillers.

[0009] Therefore, an object of the present invention is to provide a method for measuring silica powder that can accurately measure the content ratio of hollow silica particles contained in the silica powder, as well as a silica powder with a reduced content ratio of hollow silica particles and a method for producing the same.

Means for Solving the Problems

[0010] In order to solve the above problems, the present invention includes the following inventions.

[0011] The present invention [1] includes a preparation step of mixing silica powder with a liquid having a refractive index difference of 0.03 or more from the silica powder to prepare a silica-containing liquid, an arrangement step of arranging the silica-containing liquid in a film shape to obtain a silica liquid film, and an observation step of observing the silica liquid film, in this order, for a method of measuring silica powder.

[0012] The present invention [2] includes the measurement method according to the above [1], wherein in the observation step, the number of silica particles and the number of hollow silica particles are measured.

[0013] The present invention [3] includes the measurement method according to the above [1] or [2], wherein in the arrangement step, the film thickness of the silica liquid film is 100 μm or less.

[0014] The present invention [4] includes the measurement method according to any one of [1] to [3], wherein the refractive index difference between the liquid and the silica powder is 0.05 or more.

[0015] The present invention [5] includes the measurement method according to any one of [1] to [4], wherein the viscosity of the liquid at 25°C is 0.8 mPa·s or more.

[0016] The present invention [6] includes the measurement method according to any one of [1] to [5], wherein the vapor pressure of the liquid at 20°C is 25 mmHg or less.

[0017] The present invention [7] is the average particle diameter (D of the silica powder 50) is 1 μm or more and 40 μm or less, and includes the measurement method according to any one of [1] to [6].

[0018] The present invention [8] performs the measurement method according to any one of [1] to [7] on a plurality of lots of silica powder, and in each lot of silica powder, measures the ratio of the number of hollow silica particles to the number of silica particles, respectively. A measurement step, and a mixing step of mixing the silica powder of the lot in which the ratio is less than a predetermined value with the silica powder of the lot in which the ratio is equal to or more than the predetermined value, and includes a method for producing silica powder.

[0019] The present invention [9] includes the method for producing silica powder according to [8] above, wherein the predetermined value is 100 ppm on a number basis, and in the mixing step, silica powder having a hollow silica particle content of 100 ppm or less is produced.

[0020] The present invention

[10] includes silica powder in which the content of hollow silica particles having a particle diameter of 5 μm or more obtained by the measurement method according to any one of [1] to [7] or the production method according to [8] or [9] above is 100 ppm or less on a number basis.

Advantages of the Invention

[0021] According to the measurement method of the silica powder of the present invention, the content ratio of the hollow silica particles in the silica powder can be accurately measured. Further, according to the production method of the silica powder of the present invention, silica powder having a low content ratio of hollow silica particles can be produced. Further, according to the silica powder of the present invention, since the content ratio of the hollow silica particles is low, it can be suitably used as a filler for a sealing material of a semiconductor component.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0023] One embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to each configuration described below, and various modifications are possible within the scope shown in the claims. Also, different embodiments and examples are included in the technical scope of the present invention.

[0024] 1. Measurement Method An example of the measurement method of the silica powder of the present invention is a method for measuring the number of silica particles contained in the silica powder, which comprises a preparation step, an arrangement step, and an observation step in this order. Hereinafter, each step will be described in detail.

[0025] 1-1. Preparation Step In this step, a silica-containing liquid is prepared. That is, silica powder and a liquid are mixed.

[0026] The silica powder is an aggregate composed of a plurality of silica particles and is the object to be measured. The average particle diameter (D 50 ) of the silica powder is, for example, 1 μm or more, preferably 2 μm or more, more preferably 3 μm or more, and is, for example, 40 μm or less, preferably 20 μm or less, more preferably 10 μm or less. The measurement method of the present invention is suitable for observing the hollow silica particles contained in the silica powder having the above average particle diameter. Also, the silica powder having the above average particle diameter is suitable as a filler for a sealing material. The average particle diameter (D 50 ) is the particle diameter at which the volume cumulative in the particle size distribution curve obtained by the laser diffraction method is 50%. Specifically, 100 mg of silica powder is dispersed in 40 mL of water, and the sample is prepared by dispersing it with a homogenizer at an output of 40 W for 10 minutes. The particle size distribution of the sample is measured using a laser diffraction type particle size distribution measuring device, and it can be obtained from the obtained particle size distribution.

[0027] The silica powder is preferably spherical silica powder. That is, the silica powder is preferably a powder composed of a large number of spherical silica particles. Specifically, when observing 1000 silica particles included in the silica powder with a scanning electron microscope for the shape of each particle, measuring the circularity for each particle, and the average is 0.9 or more, the silica powder is regarded as spherical silica powder. Also, in each particle, a silica particle with a circularity of 0.9 or more is regarded as a spherical silica particle. The circularity is calculated by 4π×(area) / (perimeter length). 2 It is calculated by this formula. The measurement can be carried out using an image processing program (for example, AnalySIS manufactured by Soft Imaging System GmbH). Also, the silica particles included in the silica powder are preferably independent. Being independent means that the silica particles are less likely to form aggregates (both primary aggregates and secondary aggregates). Specifically, in the silica powder, (BET specific surface area) / (calculated value of specific surface area) is in the range of 0.85 or more and 1.35 or less. The BET specific surface area is the specific surface area measured by the BET method. The calculated value of the specific surface area can be calculated by 6 / (density×D 50 ), and the density of silica in this calculation is 2.2 g / cm 3 . The measurement method of the present invention is particularly suitable for measuring independent and spherical silica powder.

[0028] The silica powder preferably contains substantially no impurities other than silica particles. The proportion of impurities is, for example, 1 mass% or less, preferably 0.1 mass% or less.

[0029] The silica powder may be either hydrophilic silica or hydrophobic silica. The silica powder is produced by a dry method (e.g., combustion method, arc method) or a wet method (e.g., sol-gel method, gel method, precipitation method). Since the produced silica powder (raw silica) has silanol groups on its surface, it generally exhibits hydrophilicity. That is, the raw silica is hydrophilic silica. On the other hand, hydrophobic silica is silica particles whose surface has been treated to exhibit hydrophobicity with respect to the raw silica. Examples of the hydrophobic treatment agent include silane coupling agents, silylating agents (trimethylsilylating agents, dimethylsilylating agents, etc.), silicone oils, siloxanes, metal alkoxides, and the like.

[0030] The refractive index (nDp) of the silica powder, that is, the refractive index (nDp) of the silica particles, is generally 1.46. The refractive index of the silica powder can also be measured by the immersion method using an Abbe refractometer, as referred to in, for example, WO2019 / 177004.

[0031] The liquid is not limited as long as the difference in refractive index from the silica powder is 0.03 or more. The difference in refractive index from the silica powder is preferably 0.05 or more, more preferably 0.10 or more. The upper limit is not limited, and for example, it may be 0.40 or less, preferably 0.25 or less. The refractive index of the liquid may be higher or lower than the refractive index of the silica powder. Specifically, the refractive index of the liquid is, for example, 1.43 or less, preferably 1.41 or less, more preferably 1.36 or less, or, for example, 1.49 or more. By using a liquid with a difference in refractive index from the silica powder of the above lower limit or more, hollow silica particles and solid silica particles can be confirmed and discriminated in the observation process. The refractive index of the liquid can generally adopt known values, but it can also be measured using an Abbe refractometer under the condition of 25°C.

[0032] The viscosity of the liquid is not limited as long as the silica powder can be dispersed in the liquid. For example, it is 0.3 mPa·s or more, preferably 0.8 mPa·s or more, more preferably 1.5 mPa·s or more. Also, for example, it is 100 mPa·s or less, preferably 20 mPa·s or less, more preferably 10 mPa·s or less. By setting the viscosity of the liquid to be equal to or higher than the above lower limit, in the observation process, the movement of silica particles in the silica liquid film is suppressed frequently, so that it is easier to observe the silica particles. Further, by setting the viscosity of the liquid to be equal to or lower than the above upper limit, the silica powder can be surely dispersed in the liquid in a short time. The viscosity of the liquid is the viscosity at 25°C, and known values may be used.

[0033] The vapor pressure of the liquid is, for example, 100 mmHg or less, preferably 25 mmHg or less, more preferably 20 mmHg or less. The lower limit is not limited, and for example, it may be 0.1 mmHg or more. By setting the vapor pressure of the liquid to be equal to or lower than the above upper limit, in the observation process, the aggregation or movement of silica particles due to the evaporation of the liquid is suppressed, so that the silica particles can be surely observed individually in a dispersed and stable state. The vapor pressure of the liquid is the vapor pressure at 20°C, and known values may be used.

[0034] Specific examples of such liquids include water (1.33; 0.9 mPa·s; 18 mmHg), methanol (1.33; 0.5 mPa·s; 95 mmHg), acetone (1.36; 0.3 mPa·s; 182 mmHg), ethanol (1.36; 1.1 mPa·s; 43 mmHg), acetic acid (1.37; 1.1 mPa·s; 11 mmHg), methyl ethyl ketone (1.38; 0.4 mPa·s; 78 mmHg), n-propanol (1.39; 1.9 mPa·s; 33 mmHg), tetrahydrofuran (1.41; 0.5 mPa·s; 145 mmHg), cyclohexane (1.43; 0.9 mPa·s; 77 mmHg), toluene (1.50; 1.6 mPa·s; 22 mmHg), o-dichlorobenzene (1.55; 1.3 mPa·s; 1.2 mmHg), 1,2,4-trichlorobenzene (1.57; 1.9 mPa·s; 0.3 mmHg), and the like. The numbers in parentheses indicate the refractive index (nDs), the viscosity at 25°C, and the vapor pressure at 20°C for each component, respectively.

[0035] Preferably, the liquid includes water, ethanol, acetic acid, methyl ethyl ketone, cyclohexane, toluene, acetone, etc., and more preferably, water and acetic acid. By adopting these liquids, the contour of each silica particle can be clearly confirmed, and the flow of the silica particles can be reduced. Therefore, the observation of the silica particles can be facilitated. In addition, ethanol, toluene, etc. are suitable for the measurement of both hydrophilic silica and hydrophobic silica.

[0036] Also, the liquid may be used alone or two or more kinds may be mixed. When mixing two or more kinds of liquids, the refractive index, viscosity, and vapor pressure of the mixed liquid may be obtained by allocating the values (refractive index, viscosity, or vapor pressure) of each liquid according to the weight ratio and summing them up. By adopting such a mixed liquid, the refractive index, viscosity, and vapor pressure can be adjusted to an arbitrary range by adjusting the type and mixing amount of each liquid.

[0037] When using a mixed liquid, as long as the refractive index difference between the mixed liquid and the silica powder is within the above range, liquids other than those exemplified above can also be used. Specifically, a mixed liquid of polyethylene glycol (nDs is, for example, 1.47) and water can be mentioned. From the viewpoint of adjusting the range of the refractive index difference, the mixing amount of polyethylene glycol with respect to 100 parts by mass of water is, for example, 5 parts by mass or more, preferably 10 parts by mass or more, and also, for example, 100 parts by mass or less, preferably 20 parts by mass or less.

[0038] The mixing ratio of the silica powder and the liquid only needs to be such that the silica powder can be dispersed in the liquid. The mixing amount of the silica powder with respect to 100 parts by mass of the liquid is, for example, 1 part by mass or more, preferably 10 parts by mass or more, and also, for example, 100 parts by mass or less, preferably 50 parts by mass or less. By setting the mixing amount within the above range, the distance between the silica particles dispersed in the liquid, and thus the amount of silica particles occupying the visual field range in the observation process, can be set within an appropriate range, and the observation can be facilitated.

[0039] The silica-containing liquid is prepared by mixing and stirring the silica powder and the liquid. The silica-containing liquid preferably consists only of the silica powder and the liquid.

[0040] 1 - 2. Arrangement step In this step, the silica-containing liquid is arranged in a film shape. That is, the silica-containing liquid is formed to have a desired film thickness.

[0041] For example, as shown in FIG. 1, the silica-containing liquid is dropped onto one flat plate (placement plate), and then a flat plate (coating plate) is placed thereon, so that the silica-containing liquid is arranged between the two flat plates. Subsequently, by adjusting the distance between the two flat plates, a silica liquid film with a predetermined film thickness can be obtained. Note that one of the two flat plates may utilize a stage or member etc. that is previously provided in a microscope or the like.

[0042] The flat plate only needs to have a flat plate (coating plate) located at least in the observation direction (upward direction) being transparent. However, from the viewpoints of work simplicity and ease of observation, it is preferable to use two transparent flat plates. Transparency is preferably colorless and transparent, and in particular, it is preferable to use transparent glass with a total light transmittance of 85% or more. As such a transparent glass plate, for example, a commercially available general preparate (a set of a slide glass and a cover glass) may be used.

[0043] The distance between the two flat plates, that is, the thickness of the silica liquid film is, for example, 5 μm or more, preferably 10 μm or more, more preferably 30 μm or more, and also, for example, 500 μm or less, preferably 100 μm or less, more preferably 80 μm or less. By setting the thickness of the liquid film within the above range, in the observation process, the existence of a large number of silica particles overlapping in the film thickness direction is reduced, so that the silica particles can be observed more reliably individually.

[0044] Also, at this time, the two flat plates are arranged so that their surface directions are substantially horizontal. That is, the silica liquid film is formed so that its upper and lower surfaces are substantially horizontal. Thereby, in the observation process, the movement of the silica particles in the silica liquid film, that is, the fluidity of the silica particles is suppressed, so that the observation of the silica particles can be facilitated. Substantially horizontal means within horizontal (0 degrees) ± 3 degrees.

[0045] Thereby, the silica liquid film is obtained in a state sandwiched between two flat plates.

[0046] 1-3. Observation process In this process, the silica liquid film is observed. That is, the silica powder dispersed in the silica liquid film is observed.

[0047] For example, the silica liquid film is visually observed using a microscope. The microscope may be any that can magnify and observe silica particles. Specifically, examples include a digital microscope, an optical microscope, a laser microscope, and the like. The magnification can be appropriately changed according to the particle diameter of the silica particles contained in the silica liquid film. For example, it is 100 times or more, preferably 500 times or more, more preferably 1,000 times or more, and also, for example, 10,000 times or less, preferably 6,000 times or less, more preferably 3,000 times or less. By setting the magnification to be equal to or higher than the above lower limit, each silica particle can be observed more clearly. On the other hand, by setting the magnification to be equal to or lower than the above upper limit, the field of view range can be adjusted to an appropriate size to reduce the number of fields of view, so that the observation time can be shortened. For visual observation, the silica liquid film may be directly observed through the microscope, or the silica liquid film may be photographed with an imaging device mounted on the microscope and the photographed image may be observed.

[0048] The objects to be observed are a large number of silica particles present in the silica liquid film, specifically, solid silica particles and hollow silica particles, preferably solid spherical silica particles and hollow spherical silica particles.

[0049] In the observation of the silica liquid film, the contour (thin line) of the silica particles is clearly confirmed. In the case of spherical silica particles, the spherical contour (thin circle) is confirmed (see Figure 2). Therefore, the number of contours confirmed is counted as the number of silica particles contained in the silica liquid film (and thus the silica powder to be measured).

[0050] On the one hand, in addition to the contour of the silica particles, a contour caused by a cavity is confirmed inside the silica particles. The contour due to the cavity is a circle with a thicker width compared to the line of the contour of the silica particles (see Fig. 2). Therefore, the number of the confirmed contours of the cavities is counted as the number of the hollow silica particles contained in the silica liquid film. In the present invention, the hollow silica particles refer to particles in which a contour is observed inside the silica particles. For example, particles in which the hollow diameter (the diameter of the cavity) of the hollow silica is 5% or more of the maximum diameter (diameter) of the hollow silica particles are used. The hollow diameter may be the longest diameter of the cavity (the maximum length among any two points on the circumference of the object).

[0051] On the entire surface of the silica liquid film, all the silica particles (the total of solid silica particles and hollow silica particles) and all the hollow silica particles are observed, and the respective numbers are measured by the above counting method. Thereby, the ratio of the number of hollow silica particles (N A ) to the number of silica particles (N B ), that is, the hollow silica content ratio (N B / N A ) can be calculated. Since the number of hollow silica particles contained in the silica powder is usually very small, in the calculation of the hollow silica content ratio, the number of silica particles (the total of solid silica particles and hollow silica particles) may be regarded as the same as the number of solid silica particles excluding the hollow silica particles. Further, in order to analyze the content of the hollow silica particles in more detail, the number of the hollow silica particles may be tabulated for each hollow diameter (for example, every 5 μm).

[0052] In addition to visual observation, an observation method using an image processing system may be adopted. Specifically, for example, an image processing system capable of recognizing the contour of the silica powder and the contour of the voids of the hollow silica particles with respect to an enlarged image of the silica-containing film projected on a microscope is prepared, and the number of the silica powder and the number of the hollow silica particles are automatically measured by the system to calculate the hollow silica content ratio.

[0053] According to the measurement method of the present invention, the content ratio of hollow silica particles (preferably spherical hollow silica particles) contained in silica powder (preferably spherical silica powder) can be accurately measured. In particular, since the silica powder is mixed with liquids having different refractive indices and observed, from the difference between the refractive index of the silica particles and the refractive index of the liquid, in addition to the contour of the cavities of the hollow silica particles contained in the silica powder, the contour of the outer shape of the silica particles themselves can also be confirmed. Therefore, not only the number of hollow silica particles but also the number of all silica particles can be measured. For this reason, the content ratio of hollow silica in the entire silica powder can be grasped, and it can be evaluated whether the silica powder is suitable for a desired application such as a filler for a sealing material. Further, compared with the resin kneading method, since it is not necessary to cure the resin, measurement can be performed in a short time. In addition, since the silica powder present in the liquid is observed, there are few voids other than the voids of the hollow silica particles (for example, air bubbles) in the observation range, and as a result, the hollow silica particles can be accurately observed and measured. Further, since the silica particles present in the film-like liquid are observed, silica particles that overlap in the observation direction (film thickness direction), particularly silica particles hidden on the back side, are less likely to occur, and an accurate number of silica particles can be measured. Further, since the silica powder may be mixed with a specific liquid and arranged in a film shape for observation, it is a simple measurement method.

[0054] 2. Manufacturing method of silica powder An example of the manufacturing method of the silica powder of the present invention includes a measurement step and a mixing step in this order. Hereinafter, each step will be described in detail.

[0055] 2-1. Measurement step In this step, the measurement method of the present invention is performed on a plurality of lots of silica powder, and in each lot of silica powder, the ratio of the number of hollow silica particles to the number of silica particles is measured.

[0056] First, prepare a plurality of lots of silica powder. A lot is, for example, a unit of silica powder divided into a predetermined amount. For example, when manufacturing silica powder, in a batch process, it may be the amount of silica powder produced for each batch, or it may be silica powder obtained by further dividing the silica powder produced in one batch. In a continuous process, for example, it is silica powder divided at predetermined time intervals or for each predetermined amount. Note that it is preferable that the silica powder of each lot is appropriately classified by a sieve, air classification, or the like so that there are no coarse particles or ultrafine particles.

[0057] Take a part of the plurality of lots of silica powder and perform the measurement method of the present invention on each of them. Then, as described above, calculate the hollow silica content ratio for each lot.

[0058] Then, when the hollow silica content ratio is lower than a predetermined value (threshold value), it is determined as a qualified lot, and when it is higher than the predetermined value, it is determined as a non - qualified lot. The above - mentioned predetermined value may be determined according to each standard. Considering applications such as semiconductor components, for example, in terms of the number standard, it may be 100 ppm, preferably 10 ppm.

[0059] 2 - 2. Mixing step In this step, silica powder of one specific lot is mixed with silica powder of another specific lot.

[0060] Specifically, qualified lot silica powder is mixed with unqualified lot silica powder. Thereby, the hollow silica content ratio in the mixed silica powder can be made lower than the hollow silica content ratio of the unqualified lot. At this time, generally, since the amounts of each lot are the same as each other, the mixed hollow silica content ratio can be made the average of the hollow silica content ratios of each lot. Therefore, according to the hollow silica content ratio of each lot, silica powders of two lots (or three or more lots if necessary) can be mixed to make the hollow silica content ratio of the mixed silica powder not more than a predetermined value. The silica powder obtained not more than the predetermined value is appropriately and uniformly mixed and then divided again into a predetermined amount to become silica powders of a plurality of new lots.

[0061] According to the production method of the present invention, a silica powder lot with a low content ratio of hollow silica particles can be obtained from a silica powder lot with a high content ratio of hollow silica particles.

[0062] 3. Silica powder An example of the silica powder of the present invention is a powder obtained by carrying out the production method or measurement method of the present invention, and the content of hollow silica particles having a particle diameter of 5 μm or more is 100 ppm or less, preferably 10 ppm or less on a number basis.

[0063] The silica powder is preferably spherical silica powder. The average particle diameter (D 50 ) is, for example, 1 μm or more, preferably 2 μm or more, more preferably 3 μm or more, and is, for example, 40 μm or less, preferably 20 μm or less, more preferably 10 μm or less.

[0064] Such silica powder can be used in various applications, but it can be particularly preferably used as a filler added to a sealing material for semiconductor components. By using the silica powder of the present invention in this application, when grinding the surface of the sealing material in the manufacture of semiconductor components, a smooth surface with few depressions can be formed. Therefore, defects such as disconnection in the wiring laminated on the smooth surface can be suppressed, and the yield and long-term reliability of the semiconductor can be improved.

Examples

[0065] Next, the present invention will be described in detail with reference to examples and comparative examples, but the scope of the present invention is not limited thereto.

[0066] The following silica powders were prepared. The refractive index (nDp) of the following silica powders was all 1.46. · UF-320: Excellica (registered trademark), hydrophilic spherical silica powder, average particle diameter (D50) 3.5 μm, manufactured by Tokuyama Corporation (however, particles of 20 μm or more were removed by air classification treatment) · Surface-treated UF-320: A spherical silica powder obtained by hydrophobizing Excellica (registered trademark) UF-320 with hexamethyldisilazane (manufactured by Shin-Etsu Silicone Co., Ltd., "SZ-31"), average particle diameter (D50) 3.5 μm (however, particles of 20 μm or more were removed by air classification treatment) · UF-305: Excellica (registered trademark), hydrophilic spherical silica powder, average particle diameter (D50) 2.7 μm, manufactured by Tokuyama Corporation (however, particles of 5 μm or more were removed by air classification treatment) · UF-310: Excellica (registered trademark), hydrophilic spherical silica powder , average particle diameter (D50) 3.0 μm, manufactured by Tokuyama Corporation (however, particles of 10 μm or more were removed by air classification treatment)

[0067] The various physical property measurements of the components used in the examples and comparative examples are as follows, respectively.

[0068] <Example 1> 10 mg of silica powder (UF-320) and 70 mg of water (nDs = 1.33) were mixed in a 100 mL disposable cup to prepare a silica-containing liquid. Next, the entire amount of the silica-containing liquid was dropped onto the upper surface of a slide glass (transparent substrate), and a cover glass (transparent substrate) was placed thereon. At this time, by adjusting the space between the slide glass and the cover glass, a silica liquid film with a thickness of about 50 μm was obtained. The silica liquid film sandwiched between the two glasses was placed horizontally on a digital microscope (manufactured by Keyence Corporation, "VHS-5000"), and the entire surface of the silica liquid film was visually observed at a magnification of 1,000 times under the conditions of epi-illumination / coaxial epi-illumination. A part of the enlarged image at this time is shown in Figure 2. In Example 1, as shown in Figure 2, the contour of the cavity in the hollow silica particles could be confirmed, and the contour of the silica particles could also be confirmed. Therefore, the number of silica particles and the number of hollow silica particles could be measured.

[0069] [Observation ease: Clarity of contour] When the contour of the silica particles could be clearly confirmed and the number thereof could be measured, it was evaluated as ○. When the contour of the silica particles was ambiguous but the presence of the silica particles could be confirmed and the number thereof could be measured, it was evaluated as △. When the contour of the silica particles could not be confirmed and the number thereof could not be measured, it was evaluated as ×. The results are shown in Table 1.

[0070] [Observation ease: Non-fluidity of particles] When the silica particles hardly flowed during the observation of the silica particles, it was evaluated as ○. When the silica particles flowed slightly, it was evaluated as △. When the silica particles flowed but the measurement could be performed, it was evaluated as △△. When the silica particles flowed greatly and it was difficult to perform the measurement, it was evaluated as ×. The results are shown in Table 1.

[0071] [Measurement of the number of particles] The hollow diameters of the confirmed hollow silica particles were measured and tabulated for each hollow diameter (specifically, less than 5 μm: 5 μm or more and 10 μm or less; more than 10 μm). Also, the total amount of silica particles was measured, and the hollow silica content ratio was calculated. These results are shown in Table 1.

[0072] <Examples 2 to 12> The procedure was the same as in Example 1, except that the types of silica powder and liquid were changed to those in Table 1. The results in this case are shown in Table 1. In Examples 7, 10, and 11, as polyethylene glycol (PEG), a product named PEG#400 (manufactured by NOF Corporation, refractive index 1.47, viscosity 56.0 mPa·s, vapor pressure 0.1 mmHg) was used, and the weight ratio of water to PEG was 6:1. These results are shown in Table 1.

[0073] <Comparative Examples 1 to 3> The procedure was the same as in Example 1, except that the types of silica powder and liquid were changed to those in Table 1. In Comparative Example 3, the weight ratio of water to PEG (the same as the PEG in Example 7) was 1:6. Fig. 2 shows a partial enlarged image of the silica liquid film in Comparative Example 1. In Comparative Examples 1 to 3, as represented by Fig. 2, the contour of the cavity of the hollow silica particles could be confirmed, but the contour of the silica particles could not be confirmed, and the number of the total amount of silica particles could not be measured. These results are shown in Table 1.

[0074]

Table 1

Explanation of Symbols

[0075] 1 Silica liquid film 2 Plate for placement 3 Plate for coating 4 Solid silica particles 5 Hollow silica particles

Claims

1. A preparation step of mixing silica powder with a liquid having a refractive index difference of 0.03 or more from the silica powder to prepare a silica-containing liquid; An arrangement step of arranging the silica-containing liquid in a film shape to obtain a silica liquid film; An observation step of observing the silica liquid film A method for measuring silica powder, comprising the steps in order.

2. The measurement method according to claim 1, wherein in the observation step, the number of silica particles and the number of hollow silica particles are measured.

3. The measurement method according to claim 1, wherein in the arrangement step, the film thickness of the silica liquid film is 100 μm or less.

4. The measurement method according to claim 1, wherein the refractive index difference between the liquid and the silica powder is 0.05 or more.

5. The measurement method according to claim 1, wherein the viscosity of the liquid at 25 °C is 0.8 mPa·s or more.

6. The measurement method according to claim 1, wherein the vapor pressure of the liquid at 20 °C is 25 mmHg or less.

7. The average particle diameter (D ５０ ) of the silica powder is 1 μm or more and 40 μm or less, and the measurement method according to claim 1.

8. A measurement step of performing the measurement method according to claim 1 on a plurality of lots of silica powder, and measuring the ratio of the number of hollow silica particles to the number of silica particles in each lot of silica powder; A mixing step of mixing the silica powder of the lot having a ratio less than a predetermined value with the silica powder of the lot having a ratio equal to or more than the predetermined value A method for manufacturing silica powder, comprising the steps.

9. The predetermined value is 100 ppm on a number basis, The method for manufacturing silica powder according to claim 8, wherein in the mixing step, a silica powder having a hollow silica particle content of 100 ppm or less is obtained.

10. Silica powder having a content of hollow silica particles with a particle diameter of 5 μm or more of 100 ppm or less on a number basis, obtained by the measurement method according to claim 1 or the manufacturing method according to claim 8.

Images