JP2013103850A - Silica-based particle with moisture resistance, method for producing the same, semiconductor sealing resin composition containing the particle, and substrate with coating film formed using the resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor sealing resin composition formable of a coating film which ensures little variation of its relative dielectric constant and little variation of its dielectric loss tangent under high temperature and high humidity conditions, by improving the compressive strength and moisture resistance of silica-based particles having a cavity inside, and to provide a substrate capable of retaining high moisture resistance for a long time.SOLUTION: Silica-based particles have a cavity on the inside of a nonporous shell silica layer, and have a void fraction in the range of 20-95 vol.% and an average particle diameter in the range of 0.1-50 μm. The cavities of the silica-based particles have negative pressure of ≤133 hPa. The silica-based particles have compressive strength in the range of 0.1-200 kgf/mm.

Description

  The present invention relates to silica-based particles having a high compressive strength and excellent moisture resistance, and a method for producing the same, by sealing pores present in an outer silica layer constituting silica-based particles having cavities therein. Furthermore, it is related with the resin composition for semiconductor sealing formed by mixing this silica type particle with a thermosetting resin as a filler.

Silica-based particles are known in various shapes and sizes, and their uses are diverse.
A number of methods for producing silica-based porous particles and methods for coating the surface of inorganic oxide particles with a silica-based coating have been proposed to date.

For example, in Patent Document 1 (Japanese Patent Laid-Open No. Sho 61-270201), an inorganic oxide particle (true particle size) of 1 to 20 μm is obtained by spray drying a colloidal solution containing primary particles having an average particle size of 2500 mm or less. A method for producing a spherical silica powder or the like) is disclosed.
In Patent Document 2 (Japanese Patent Laid-Open No. 6-192593), a silicate solution and an acid are added to an aqueous suspension of inorganic particles, and the mixed suspension is exposed to the influence of ultrasonic vibration. Thus, a method of coating the surface of the inorganic particles with amorphous silica is disclosed.
Furthermore, Patent Document 3 (Japanese Patent Laid-Open No. 2002-160907) discloses an inorganic oxide having an average particle diameter of 1 to 100 μm obtained by spray-drying a colloidal liquid containing inorganic oxide fine particles having an average particle diameter of 2 to 250 nm. the outer surface of the fine particle aggregates, the chemical formula _{R n Si (OR ') 4} -n formed by coating a silica-based layer comprising a hydrolyzate of an organic silicon compound represented by spherical porous particles is disclosed.

Patent Document 4 (Japanese Patent Application Laid-Open No. 2005-206436) discloses an amorphous spherical silica hollow powder having an average particle diameter of 0.5 to 8 μm, a sphericity of 0.85 or more, and an average hollowness of 20 to 70% by volume. The body and its manufacturing method are disclosed, and it is disclosed that it is excellent in strength, lightness, heat insulation, low dielectric properties and the like.
However, the amorphous spherical silica hollow powder is obtained by supplying a silica raw material powder having a specific surface area of 40 m ² / g or more and an average particle diameter of 10 μm or less into a high-temperature flame to make it spherical and hollow. In addition, there are particles having a particle size about 5 times the average particle size, the particle size distribution is non-uniform, the application is limited, and in order to make the particle size more uniform, the particle size distribution of the silica raw material powder is more It is necessary to make it uniform, and it is easy to obtain particles in which fine particles are fused on the particle surface, which is unsuitable for applications that require smoothness of the surface.

  Furthermore, in Patent Document 5 (Japanese Patent Laid-Open No. 4-104907), an alkali metal silicate aqueous solution is atomized and introduced into an air stream at 100 to 500 ° C. to form a glass balloon to adjust the removal amount of alkali metal. Thus, a method for producing a silica balloon in which the pore diameter of the silica balloon is controlled is disclosed. At this time, spray drying and ultrasonic vibration are employed as the atomizing method.

However, as a result of a test conducted by the applicant of the present invention in accordance with the spray drying method, it was difficult to efficiently obtain a desired silica balloon because a part of the glass balloon was dissolved in the alkali metal removal step. Moreover, the silica balloon obtained was only a porous silica balloon having pores, and nonporous particles having cavities inside could not be obtained.
However, although these patent documents disclose a method of coating the surface of inorganic oxide particles with a silica-based material, a method for sealing pores existing on the surface of silica-based porous particles is described in more detail. Does not describe any method for sealing only the pores existing on the surface of the particles while leaving the pores existing inside the silica-based porous particles as they are.

  Many proposals have been made for a resin composition for a semiconductor sealing material in which inorganic oxide fine particles are mixed as a filler. For example, Patent Document 6 (Japanese Patent Application Laid-Open No. 2002-37620) discloses a semiconductor package in which a spherical silica particle aggregate composed of a fired product of polyorganosiloxane particles obtained by hydrolysis and condensation of an organosilicon compound is mixed. Although a resin composition for a stopper is disclosed, there is no description about using silica-based porous particles as a filler.

  Further, Patent Document 7 (Japanese Patent Application Laid-Open No. 2001-220496) discloses a resin composition for a semiconductor sealing material in which porous silica particles obtained from a sol-gel method are mixed with an epoxy resin. However, since this porous silica particle is used for the purpose of trapping moisture entering from the outside, the pores existing on the particle surface are not sealed.

  Further, in Patent Document 8 (Japanese Patent Laid-Open No. 2010-155750), a colloidal liquid containing primary particles is spray-dried to form inorganic oxide particles (such as true spherical silica powder) having an average particle diameter of 1 to 20 μm, such as silicic acid and A method of sealing only pores existing on the particle surface by hydrolyzing and condensing the organosilicon compound, leaving the pores existing inside the silica-based porous particles as they are, is disclosed. The moisture resistance of the silica-based particles was insufficient.

JP-A 61-270201 JP-A-6-192593 JP 2002-160907 A JP 2005-206436 A JP-A-4-104907 JP 2002-37620 A Japanese Patent Laid-Open No. 2001-220696 JP 2010-155750 A

  The present invention improves the compressive strength and moisture resistance of silica-based particles having cavities therein, thereby forming a coating film with little change in relative permittivity and dielectric loss tangent under high temperature and high humidity conditions. Provided are a resin composition for encapsulating a semiconductor and a substrate capable of maintaining high moisture resistance for a long time.

The gist of the present invention is as follows.
1. A silica-based particle having a void inside a nonporous outer shell silica layer, having a porosity in a range of 20 to 95% by volume and an average particle diameter in a range of 0.1 to 50 µm.
2. The silica-based particle according to (1), wherein the silica-based particle has a negative pressure.
3. The silica-based particle according to (2), wherein the negative pressure of the cavity is 133 hPa or less.
4). The silica-based particles according to any one of the above (1) to (3), wherein the compressive strength of the silica-based particles is in the range of 0.1 to 200 kgf / mm ² .
5. The silica-based particles according to the above (1) to (4), wherein the moisture absorption rate (weight change rate) when left for 7 days in an air atmosphere at a temperature of 25 ° C. and a humidity of 90% is 0.1% or less. Silica-based particles.

6). The method for producing silica-based particles according to any one of the above (1) to (5), wherein the following steps (a) to (d) are sequentially performed.
(A) Step of preparing silica-based particle precursor particles by spray drying an alkali silicate aqueous solution in a hot air stream (b) Step of immersing silica-based particle precursor particles in an acid aqueous solution to remove alkali (c) Water 6. Heat treatment step (d) Drying / heat treatment step The method for producing silica-based particles according to (6), wherein the following step (c ′) is performed between the step (b) and the step (c).
(C ′) Drying and heat treatment step 8. The method for producing silica-based particles according to (6) or (7) above, wherein the hydrothermal treatment temperature in step (c) is 180 to 350 ° C.

9. The resin composition for semiconductor sealing containing the silica type particle in any one of said (1)-(5), and a thermosetting resin.
10. When the volume of the silica-based particles is represented by A and the volume of the thermosetting resin is represented by B, the volume ratio (A / B) is in the range of 10/100 to 95/100. The resin composition for semiconductor encapsulation as described in said (9).

11. The base material with which the coating film which consists of a resin composition as described in said (9) or (10) was formed.
12 In the high-temperature and high-humidity durability test (temperature 80 ° C., humidity 80%, holding time 1000 hours), the substrate has a relative dielectric constant change (Δε) of 0.2 or less using the resonance method before and after the test. Furthermore, the base material according to the above (11), wherein the change in dielectric loss tangent (Δtan δ) is 0.01 or less.

According to the silica-based particles of the present invention, it is possible to obtain a coating film having high compressive strength, high moisture resistance, and almost no change in relative permittivity and dielectric loss tangent.
According to the method for producing silica-based particles of the present invention, it is possible to produce silica-based particles that can obtain a coating film that has high moisture resistance and has a low relative dielectric constant and little change in dielectric loss tangent.
The resin composition for encapsulating a semiconductor of the present invention can provide a substrate on which a coating film having high moisture resistance and almost no change in relative permittivity and dielectric loss tangent is formed.

  Hereinafter, the silica-based particles according to the present invention, the method for producing the silica-based particles, the semiconductor sealing resin composition containing the particles, and the substrate on which a coating film is formed from the resin composition will be specifically described.

[Silica-based particles]
The silica-based particles according to the present invention have cavities inside the nonporous shell silica layer, the porosity is in the range of 20 to 95% by volume, and the average particle size is in the range of 0.1 to 50 μm. It is characterized by that.
The porosity of the particles is preferably in the range of 20 to 95% by volume, more preferably 25 to 90% by volume.
When the porosity is less than 20% by volume, the refractive index is not sufficiently low, and application to a resin having a low refractive index may not be possible.
It is difficult to obtain a silica-based particle having a porosity of more than 95% by volume. Even if it is obtained, the shell may be thin depending on the particle diameter, and the particle strength may be insufficient.

  The silica-based particles of the present invention have an average particle diameter in the range of 0.1 to 50 μm. Those having an average particle size of less than 0.1 μm are difficult to produce using the spray drying method in consideration of productivity using the spray drying method. Silica-based particles having an average particle diameter exceeding 50 μm are not suitable for semiconductor applications. On the other hand, silica-based particles having an average particle diameter of 0.1 to 10 μm are more preferable for use as a mounting material for semiconductors including three-dimensional mounting technology.

When the above silica-based particles are produced, when the drying / heating treatment is performed under reduced pressure, silica-based particles having a negative pressure inside the outer shell layer of the obtained silica-based particles can be obtained.
Therefore, the silica-based particles obtained by drying and heat treatment under reduced pressure have an average particle diameter in the range of 0.1 to 50 μm, have cavities inside the outer shell silica layer, and the porosity of the cavities. Is in the range of 20 to 95% by weight, the outer shell silica layer is nonporous, and the inside of the cavity is negative pressure.
The negative pressure inside the cavity is preferably 133 hPa or less.

Silica-based particles having cavities therein have a low refractive index of 1.1 to 1.4. If the refractive index of the hollow particles is 1.1 or more, it is easy to obtain a coating film having a refractive index of 1.2 or more, and a coating film having a high antireflection effect can be obtained with any substrate of glass or resin. Further, if the refractive index of the particles is 1.1 or more, a sufficiently thick shell is formed, and the mechanical strength of the particles is increased.
If the refractive index of silica-based particles having cavities therein is 1.4 or less, it is easy to obtain a coating film having a refractive index of 1.4 or less. A membrane is obtained.

  As the silica particles of the present invention, silica particles such as silica particles, silica / alumina, silica / zirconia, silica / titania, etc. containing inorganic oxides other than silica in less than 50% by weight are used. Especially, the silica particle which consists only of silica and originates in a silica sol with a uniform particle diameter can be used conveniently.

The compressive strength of the silica-based particles is preferably in the range of 0.1 to 200 kgf / mm ² .
When the compressive strength is less than 0.1 kgf / mm ² , the strength is weak, and the particles may be broken in the mixing operation with the resin or in the coating film, and the shape may not be maintained. Further, if the compressive strength exceeds 200 kgf / mm ² , the particles themselves become brittle and may be broken due to collisions between the particles.

  The silica-based particles of the present invention preferably have moisture resistance. Here, the moisture resistance means that the moisture absorption rate (weight change rate) when the silica-based particles are left in an air atmosphere at a temperature of 25 ° C. and a humidity of 90% for 7 days is 0.1% or less. . When used in applications where moisture is not desired, if the moisture absorption rate of the particles themselves exceeds 0.1%, moisture is taken into the coating film, which is a significant factor in the occurrence of defects.

[Method for producing silica-based particles]
The method for producing silica-based particles according to the present invention is characterized by comprising the following steps (a) to (d).
(A) Step of preparing silica-based particle precursor particles by spray drying an alkali silicate aqueous solution in a hot air stream (b) Step of immersing silica-based particle precursor particles in an acid aqueous solution to remove alkali (c) Water Heat treatment step (d) Drying and heat treatment step

Step (a)
An aqueous silica silicate solution is spray-dried in a hot air stream to prepare silica-based particle precursor particles.
As the alkali silicate used in the present invention, sodium silicate and potassium silicate soluble in water are usually used.
The SiO ₂ / M ₂ O molar ratio of alkali silicate (where M represents an alkali metal) is preferably in the range of 1 to 5, more preferably 2 to 4.
When the SiO ₂ / M ₂ O molar ratio of the alkali silicate is less than 1, the alkali amount is too large, so that not only acid cleaning in the step (b) described later becomes difficult, but also the deliquescence of the spray-dried product is remarkable. Therefore, silica-based fine particles may not be obtained.
When the SiO ₂ / M ₂ O molar ratio of the alkali silicate exceeds 5, the solubility of the alkali silicate is reduced, and it is difficult to prepare an aqueous solution. Even if it is possible, silica fine particles of several nm or less are generated in the aqueous solution. In some cases, silica-based particle precursor particles that can be used in the present invention may not be obtained even by spray drying.

The concentration of the alkali silicate aqueous solution as SiO ₂ is preferably in the range of 1 to 30% by weight, more preferably 5 to 28% by weight.
When the concentration of the alkali silicate aqueous solution as SiO ₂ is less than 1% by weight, it may be inefficient when productivity is taken into consideration.
If the concentration of the alkali silicate aqueous solution as SiO ₂ exceeds 30% by weight, the stability as the alkali silicate aqueous solution is remarkably lowered and the viscosity may become high and spray drying may be difficult. In some cases, the diameter distribution, the thickness of the outer shell, and the like are extremely nonuniform, and the application may be limited.

  The alkali silicate aqueous solution is spray-dried in a hot air stream, and the spray-drying method is not particularly limited as long as silica-based fine particles to be described later are obtained, but a conventionally known method such as a rotating disk method, a pressurized nozzle method, and a two-fluid nozzle method. This method can be adopted. In the present invention, the two-fluid nozzle method is suitable for obtaining particles having cavities inside.

When producing the silica-based particles of the present invention, the inlet temperature in the spray drying is in the range of 300 to 600 ° C., more preferably 350 to 550 ° C., and the outlet temperature is 120 to 300 ° C., more preferably 130 to 250 ° C. It is preferable to be in the range.
At this time, when the inlet temperature in spray drying is less than 300 ° C., it may vary depending on the outlet temperature, but silica-based particles having cavities inside may not be obtained.
When the inlet temperature in spray drying exceeds 600 ° C., ruptured silica-based particle precursor particles are formed, and it may be difficult to obtain silica-based particles having cavities inside. Even if this is the case, the thickness of the outer shell becomes thin, and the strength of the resulting silica-based particles may be insufficient.

When the outlet temperature of hot air is less than 120 ° C., silica-based particles having cavities inside may not be obtained.
When the outlet temperature of the hot air exceeds 300 ° C., a silica-based particle precursor particle in a ruptured state is formed, and it may be difficult to obtain silica-based particles having cavities inside. However, the thickness of the outer shell may be reduced, and the strength of the resulting silica-based particles may be insufficient.

Step (b)
Silica-based particle precursor particles are immersed in an acid aqueous solution to remove alkali.
Examples of the acid include mineral acids such as hydrochloric acid, nitric acid, and sulfuric acid, and organic acids such as acetic acid, tartaric acid, and malic acid. Usually, such an acid is used, but a cation exchange resin or the like can also be used. In the present invention, mineral acids such as hydrochloric acid, nitric acid and sulfuric acid are preferably used.

When the silica-based particle precursor particles are immersed in the acid aqueous solution, the molar ratio (Ma) / (Msp) between the number of moles of M ₂ O (Msp) and the number of moles of acid (Ma) in the silica particle precursor particles is 0. It is preferable to immerse so that it may become the range of 1.6-4.7, and also 1-4.
When the molar ratio (Ma) / (Msp) is less than 0.6, the amount of acid relative to M ₂ O is too small, so that condensation of silicic acid, which is considered to occur along with the removal of alkali, silica of silicic acid In some cases, the skeletonization does not proceed and the silica-based particle precursor particles are partially dissolved, or the dissolved alkali silicate is gelled.
Even if the molar ratio (Ma) / (Msp) exceeds 4.7, the above-described condensation and skeletonization of silicic acid does not proceed, and the acid is excessive and not economical.

The concentration of the silica-based particle precursor particles when immersed in an aqueous acid solution is 1 to 30 wt% as SiO _2, and more preferably in the range of 5 to 25 wt%.
The concentration of the silica-based particle precursor particles when immersed in aqueous acid solution in the case of less than 1% by weight SiO _2, alkali removal, there is no problem in cleanability production efficiency decreases. Further, depending on the molar ratio of the acid and silica described above and the silica and alkali molar ratio of the alkali silicate, the concentration of the acid may be lowered, and the silica-based particle precursor particles may be partially dissolved or dissolved silicic acid. The alkali may gel.
If the concentration of the silica-based particle precursor particles when immersed in an acid aqueous solution exceeds 30% by weight as SiO ₂ , the concentration may be too high and alkali removal and cleaning efficiency may be reduced. When the particle diameter of the particles is small, the viscosity of the dispersion is particularly high, and alkali removal and cleaning efficiency may be reduced.

The conditions for removing the alkali are not particularly limited as long as the alkali can be removed, but the temperature is generally in the range of 5 to 70 ° C. and the time is in the range of 0.5 to 24 hours.
Subsequently, it wash | cleans by a conventionally well-known method. For example, it may be filtered and washed with pure water.
In the present invention, the alkali removal and washing can be repeated as necessary.
The remaining amount of alkali after washing varies depending on the use, but it is preferably 0.5% by weight or less, more preferably 0.1% by weight or less as M ₂ O.

Step (c)
The silica-based particle precursor particle dispersion is hydrothermally treated.
Since the silica-based particle precursor particles obtained from the step (b) need to heat the dispersion, it is necessary to put the mixed solution in a pressure vessel such as an autoclave.
When the mixed solution is heat-treated at a temperature of 180 to 350 ° C., the inside of pores existing on the surface of the silica-based particle precursor particles is blocked with the silica-based particle precursor particles and / or a solution thereof. The pores can be sealed. The heating temperature is preferably 200 to 250 ° C.

  In this stage, a conventionally known liquid silicon compound such as silicic acid or an organosilicon compound can be further added to the mixed solution for the purpose of densely sealing the pores on the particle surface. For example, as described in Japanese Patent Application Laid-Open No. 2010-155750, hydrothermal treatment may be performed by adding silicic acid or an organosilicon compound in the stated ratio during hydrothermal treatment of silica-based particles. This is because even if the liquid silicon compound is added, they hardly penetrate into the silica-based particle precursor particles, and only the pores existing on the surface are sealed. Silica-based particles can be obtained.

  Here, when the temperature is less than 180 ° C, pores present on the surface of the silica-based particle precursor particles may not be sufficiently sealed, and when the temperature exceeds 350 ° C, Dissolution of the silica-based particle precursor particles proceeds, and the dissolved product (and further, the dissolved silica particles) is deposited on the particles after heating to become non-porous particles or non-spherical particles. This is not preferable.

The heat treatment is preferably performed for 5 to 20 hours, preferably 10 to 16 hours. Here, if the treatment time is less than 5 hours, pores present on the surface of the silica-based particle precursor particles may not be sufficiently sealed, and the treatment time exceeds 20 hours. And the dissolution of the silica-based particle precursor particles proceeds, and the dissolved product (and the dissolved silica particles) is deposited on the particles after the heating, and the non-porous particles, non-spherical particles, etc. This is not preferable.
In this step, the silica particles contained in the mixed solution are dissolved, and this dissolved material enters at least the inside of the pores existing on the surface of the silica-based particle precursor particles, and is thus fixed on the surface of the particles. Existing pores can be sealed.

Step (d)
Next, it is dried and heated.
The drying / heat treatment temperature is preferably in the range of 90 to 1200 ° C, more preferably 110 to 1150 ° C.
When the drying / heat treatment temperature is less than 90 ° C., the pores may not disappear, and silica-based particles having a nonporous outer shell may not be obtained.
Even when the drying / heat treatment temperature exceeds 1200 ° C., it does not become non-porous, and the particle strength does not further improve, resulting in aggregate particles that are difficult to disperse depending on the temperature and particle size. There is.

Step (c ′)
This step (c ′) is an optional step, and is a step of drying and heat-treating the silica-based particle precursor particles between the step (b) and the step (c).
The drying / heating temperature is preferably 30 to 120 ° C, more preferably 40 to 100 ° C.
Moreover, it is preferable that drying and heat processing are performed under reduced pressure, and the inside of the outer shell layer of the obtained silica-based particles is preferably negative pressure, and the negative pressure inside the cavity is preferably 133 hPa or less.
When the drying / heat treatment temperature is less than 30 ° C., a large amount of adhering water remains, and there is a problem that productivity is reduced because the drying treatment takes a long time in addition to the limitation of use.
When the drying / heat treatment temperature exceeds 120 ° C., pores formed when alkali is removed may disappear.

[Resin composition for semiconductor encapsulation]
The resin composition for semiconductor encapsulation according to the present invention is obtained by mixing the silica-based particles with a thermosetting resin as a filler.
As said thermosetting resin, if it is generally used for semiconductor sealing, it can be especially used without a restriction | limiting. Furthermore, among thermosetting resins, it is preferable to use a photocurable resin or a thermosetting resin. As such materials, epoxy resins, polyimide resins, bismaleimide resins, acrylic resins, methacrylic resins, silicon resins, BT resins, and cyanate resins can be suitably used. For example, epoxy resins include bisphenol type epoxy resin, novolak type epoxy resin, triphenolalkane type epoxy resin, epoxy resin having biphenyl skeleton, epoxy resin having naphthalene skeleton, dicyclopentadienephenol novolak resin, phenol aralkyl type epoxy. Examples thereof include resins, glycidyl ester type epoxy resins, alicyclic epoxy resins, heterocyclic type epoxy resins, and halogenated epoxy resins. Moreover, about these resin compounds, you may use individually and may mix and use 2 or more types.

  When the weight of the silica particles is represented by A and the weight of the thermosetting resin is represented by B, the weight ratio (A / B) is 10/100 to 95/100, preferably It is preferable to mix so that it may become 30/100-80/100. Here, when the weight ratio is less than 10/100, the low thermal expansion coefficient effect and thermosetting curing, which are the characteristics of the silica-based particles, deteriorate, and when the weight ratio exceeds 95/100, fluidity Since it becomes difficult to seal a semiconductor efficiently, it is not preferable.

  In the preparation of the semiconductor sealing resin composition, a curing agent such as a phenol compound, an amine compound, or an acid anhydride is used. As this hardening | curing agent, if it is used for the hardening | curing agent of an epoxy resin, it can be used without a restriction | limiting. Among these, bisphenol type resin, novolak resin, triphenolalkane type resin, resol type phenol resin, phenol aralkyl resin, biphenyl type phenol resin, naphthalene type phenol resin, cyclopentadiene having two or more phenolic hydroxyl groups in one molecule. It is preferable to use phenolic resins such as type phenolic resins and acid anhydrides such as methylhexahydrophthalic acid, methyltetrahydrophthalic acid, and methylnadic anhydride.

Furthermore, a coloring agent, a stress relaxation agent, an antifoaming agent, a leveling agent, a coupling agent, a flame retardant, a curing accelerator, and the like can be added to the semiconductor sealing resin composition as necessary.
Moreover, the said semiconductor sealing resin composition can be prepared by a conventionally well-known method. That is, the resin composition is, for example, mixed with the thermosetting resin, the silica-based particles, the curing agent and, if necessary, the additive, kneaded with a roll mill or the like, and then subjected to vacuum defoaming treatment. Prepared.

[Substrate with coating]
A method for forming a coated substrate using the resin composition for semiconductor encapsulation is a known method such as a dipping method, a spray method, a spinner method, a roll coating method, a bar coating method, a gravure printing method, or a micro gravure printing method. The film can be formed by coating the substrate with a conventional method such as drying and curing, and a substrate with a film can be produced.

  When the coated substrate is used in applications where moisture is not required, in the high temperature imperial durability test of the coated substrate, the change in relative dielectric constant (Δε) exceeds 0.2, and the dielectric loss tangent ( When Δtan δ) exceeds 0.01, moisture is taken into the coating film, which is a significant factor in the occurrence of defects.

[Measuring method]
Next, the measurement method used in the present invention is as follows.
(1) Average particle diameter of silica-based particles A slurry liquid (solid content concentration of 0.1 to 5% by mass) prepared by dispersing a powder of silica-based particles in a 40% by weight glycerin-containing aqueous solution is prepared. Dispersion treatment is performed for 5 minutes on a sound wave generator (US-2 type manufactured by Iuch). Next, a sample is taken from the dispersion whose concentration has been adjusted by adding the glycerin aqueous solution, and the sample is placed in a glass cell (size of 10 mm in length, 10 mm in width, and 45 cm in height). The average particle diameter is measured using Seiko Seisakusho: CAPA-700).

(2) Average particle diameter of silica-based fine particles Solid content prepared by mixing 19.85 g of pure water with 0.15 g of an aqueous dispersion sol (solid content 20 wt%) of silica-based fine particles having a nano-sized particle size. A sample having a content of 0.15% was placed in a quartz cell having a length of 1 cm, a width of 1 cm, and a height of 5 cm, and an ultrafine particle size analyzer by dynamic light scattering method (model ELS-Z2 manufactured by Otsuka Electronics Co., Ltd.). ) To measure the particle size distribution of the particle group. In addition, the average particle diameter as used in the field of this invention shows the value computed by cumulant analysis of this measurement result.

(3) True density of silica-based particles The true density of silica-based particles before hydrothermal treatment is determined using a pycnometer by a measurement method defined in Japanese Industrial Standard JIS Z8807.

(4) Porosity of silica-based particles Using the true density of silica-based particles before hydrothermal treatment determined in (3) above, the following formula is used. The numerical value of 2.2 used here indicates the density of silica.
Porosity (%) = [2.2− (true density of silica-based particles before hydrothermal treatment)] / 2.2 × 100

(5) pH of the mixed solution containing silica-based particles
A pH of which the pH is adjusted with a standard solution of pH 4, 7 and 9 after stirring a dispersion whose pH is adjusted by adding ammonia or the like to a mixed solution containing silica-based particles for 30 minutes or more in a thermostatic bath at 25 ° C. Measurement is performed by inserting a glass electrode of a meter (H22, F22).

(6) Compressive strength of silica-based particles From a powder of silica-based particles, one particle having an average particle diameter of ± 0.5 μm is taken as a sample, and a micro compression tester (manufactured by Shimadzu Corporation, MCTM-200) is used. Using this, a load is applied to the sample at a constant load speed, and the weight at the time when the particles are broken is defined as the compressive strength (kgf / mm ² ). Further, this operation is repeated four times, the compressive strength is measured for five samples, and the average value is taken as the particle compressive strength.

(7) Moisture absorption rate of silica-based particles A predetermined amount of silica-based fine particles is placed in a magnetic crucible, and the weight thereof is weighed using a precision electronic balance (ASPONE, ASP214). Next, the magnetic crucible is placed in a desiccator adjusted to a temperature of 25 ° C. and a humidity of 90% and left for 7 days. Thereafter, the magnetic crucible is taken out and weighed with a precision electronic balance. Next, the weight change is calculated, and the value is defined as the moisture absorption rate.

(8) Method for measuring void internal pressure of silica-based particles The void internal pressure was measured by the following method and evaluated according to the following criteria.
A 100 cc glass bottle connected to one of the U-shaped manometers is charged with a weight equivalent to 40 cc of silica-based fine particles, and then 50 cc of a 48 wt% sodium hydroxide aqueous solution is added. Closed and sealed. At this time, the space of the air layer inside the glass bottle was 10 cc. Next, while stirring with a magnetic stirrer, the mixture was heated at 80 ° C. for 15 hours in an oil bath to dissolve the silica-based fine particles, and then cooled to room temperature. The space of the air layer at this time was 25 cc (the volume of the air layer inside the glass bottle: 10 cc and the internal void volume of the silica-based particles: approximately 16 cc). Thereby, it turned out that the internal space | gap of the silica type fine particle was open | released by melt | dissolution of the silica. Next, the other U-tube manometer was connected to a 100 cc glass bottle containing 90 cc of a 48% aqueous sodium hydroxide solution, and the vapor pressures inside both glass bottles were made equal. Thus, the internal pressure of the silica-based fine particles can be calculated from Boyle's law based on the differential pressure measured with a manometer. The pressure inside the U-shaped tube manometer at this time was read to calculate the void internal pressure.

Evaluation standard differential pressure is 133 hPa or less: ◎
Differential pressure is over 133 hPa to 500 hPa: ○
Differential pressure is over 500 hPa and less than 1013 hPa: Δ
Differential pressure is 1013 hPa: ×

(9) Durability test The durability test was performed by measuring the relative dielectric constant and dielectric loss tangent of the substrate in a high temperature and high humidity test.
1. Preparation of base material Mixed epoxy resin of bisphenol A type epoxy resin and bisphenol F type epoxy resin (manufactured by Tohto Kasei Co., Ltd., ZX-1059, epoxy equivalent of about 165), curing agent (manufactured by Shin Nippon Rika Co., Ltd., Ricacid MH- 700) and a curing accelerator (manufactured by Shikoku Kasei Co., Ltd., Curazole 2PHZ-PW) mixed at 100/86/1 by weight and silica-based particles mixed at a volume ratio of 50/50. These were kneaded using a resin mixing device and subjected to reduced pressure defoaming treatment to prepare a resin composition.
The prepared composition was coated on a PET substrate with a resin composition for forming a silica-based film by a dip coating method. The application method is not particularly limited even if any conventionally known method is used. The coated film was dried at 70 ° C. for 16 hours, and then baked and cured at 150 ° C. for 3 hours to prepare a substrate for evaluation.

2. Measuring method of relative dielectric constant and dielectric loss tangent After removing the adsorbed water attached to the surface by drying the substrate prepared in 1 above at 120 ° C. for 1 hour, a coaxial resonator (AT Co., Ltd.) The relative dielectric constant (ε1) and the dielectric loss tangent (tan δ1) before the durability test were measured using the product, frequency: 9.4 GHz, analysis software: three-dimensional electromagnetic field analysis, MW-Studio manufactured by CST. Thereafter, the substrate was allowed to stand for 1000 hours under conditions of 80 ° C. and 80% humidity using a high-temperature and high-humidity durability tester (manufactured by ESPEX Co., Ltd., small environmental tester SH-241). Thereafter, the relative permittivity (ε2) and dielectric loss tangent (tan δ2) of the durability test were measured by the same method as the above relative permittivity measuring method. Next, the difference between each physical property before and after the durability test was calculated and used as the amount of change in each physical property (Δε, Δtan δ).

  Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited to the scope described in these examples.

[Example 1]
Preparation of silica-based particles (1) Using 3000 g of water glass aqueous solution (SiO ₂ / Na ₂ O molar ratio 3.2, SiO ₂ concentration 24 wt%) at a flow rate of 0.62 kg / hr in one of two fluid nozzles, The other nozzle was sprayed with hot air at an inlet temperature of 400 ° C. at a flow rate of 31800 L / hr (air / liquid volume ratio 63600) to obtain silica-based particle precursor particles (1). At this time, the outlet temperature was 150 ° C.
Subsequently, 500 g of silica-based particle precursor particles (1) were immersed in 3200 g of a 10 wt% sulfuric acid aqueous solution and stirred for 1.5 hours. At this time, the solid content (SiO ₂ ) concentration was 10.2 wt%, the temperature of the dispersion was 35 ° C., and the pH was 3.0. The molar ratio (Ma) / (Msp) with the number of moles of acid (Ma) was 1.2.

Thereafter, the mixed liquid containing the silica-based particle precursor particles (1) was put in a pressure vessel such as an autoclave, hydrothermally treated at 200 ° C. for 16 hours, cooled to room temperature, and extracted.
The obtained liquid mixture was filtered with a quantitative filter paper (No. 5C, manufactured by Advantech Co., Ltd.) using a Buchner funnel (3.2 L manufactured by Sekiya Rika Glass Instruments Co., Ltd.), and then repeatedly washed to obtain a surface. A cake-like substance comprising an aggregate of sealed silica-based particles was obtained.
Subsequently, it dried and heat-processed at 120 degreeC for 24 hours with the dryer, and prepared the silica type particle | grains (1).
The average particle diameter, the true density, the porosity, the moisture absorption rate, and the compressive strength of the obtained silica-based particles (1) were measured, and the results are shown in Table 1.

[Example 2]
Preparation of silica-based particles (2) Using 3000 g of water glass aqueous solution (SiO ₂ / Na ₂ O molar ratio 3.2, SiO ₂ concentration 24 wt%) at a flow rate of 0.62 kg / hr in one of two fluid nozzles, The other nozzle was sprayed with hot air at an inlet temperature of 400 ° C. at a flow rate of 31800 L / hr (air / liquid volume ratio 63600) to obtain silica-based particle precursor particles (2). At this time, the outlet temperature was 150 ° C.
Next, 500 g of silica-based particle precursor particles (1) were immersed in 3200 g of a 10 wt% sulfuric acid aqueous solution and stirred for 1.5 hours. At this time, the solid content (SiO ₂ ) concentration was 10.2 wt%, the temperature of the dispersion was 35 ° C., and the pH was 3.0. The molar ratio (Ma) / (Msp) with the number of moles of acid (Ma) was 1.2.
Next, the silica-based particles (2) were prepared by drying and heating at 120 ° C. for 24 hours while evacuating with a vacuum pump at a reduced pressure of 1 hPa with a dryer.

Thereafter, a solution obtained by adding 10% by weight of a silica solution containing 4.5% by weight in terms of SiO2 to the mixed solution containing silica-based particles (2) to the weight of the silica-based particles (2) is put in a pressure vessel such as an autoclave. The mixture was hydrothermally treated at 200 ° C. for 16 hours, cooled to room temperature and extracted.
The obtained liquid mixture was filtered with a quantitative filter paper (No. 5C, manufactured by Advantech Co., Ltd.) using a Buchner funnel (3.2 L, manufactured by Sekiya Rika Glass Instrument Co., Ltd.), then repeatedly washed, and surface-sealed. A cake-like substance composed of an aggregate of silica-based particles was obtained.
Subsequently, it dried and heat-processed at 120 degreeC for 24 hours with the dryer, and prepared the silica type particle (2).
The average particle diameter, the true density, the porosity, the moisture absorption rate, and the compressive strength of the obtained silica particles (2) were measured, and the results are shown in Table 1. The void internal pressure of the silica-based particles (2) was ◎.

[Example 3]
Silica-based particles (3) were prepared in the same manner as in Example 1 except that the flow rate of the water glass aqueous solution was 0.08 kg / hr.
The average particle diameter, the true density, the porosity, the moisture absorption rate, and the compressive strength of the obtained silica-based particles (3) were measured, and the results are shown in Table 1.

[Example 4]
Silica-based particles (4) were prepared in the same manner as in Example 1 except that the air flow rate was 15900 L / hr.
The average particle diameter, the true density, the porosity, the moisture absorption rate, and the compressive strength of the obtained silica-based particles (4) were measured, and the results are shown in Table 1.

[Example 5]
Silica-based particles (5) were prepared in the same manner as in Example 2, except that the air flow rate was 15900 L / hr.
The average particle diameter, the true density, the porosity, the moisture absorption rate, and the compressive strength of the obtained silica particles (5) were measured, and the results are shown in Table 1. The void internal pressure of the silica-based particles (5) was ◎.

[Example 6]
Silica-based particles (6) were prepared in the same manner as in Example 1, except that the flow rate of air was 5500 L / hr.
The average particle diameter, the true density of the particles, the porosity, the moisture absorption rate, and the compressive strength of the obtained silica-based particles (6) were measured, and the results are shown in Table 1.

[Comparative Example 1]
In Example 1, silica-based particles (7) were similarly prepared except that hydrothermal treatment was not performed.
The average particle diameter, the true density, the porosity, the moisture absorption rate, and the compressive strength of the obtained silica-based particles (7) were measured, and the results are shown in Table 1.

[Comparative Example 2]
Silica-based particles (8) were prepared in the same manner as in Example 1 except that the hydrothermal treatment temperature was 150 ° C.
The average particle diameter, the true density, the porosity, the moisture absorption rate, and the compressive strength of the obtained silica-based particles (7) were measured, and the results are shown in Table 1.

[Comparative Example 3]
A fused silica particle containing a silica solution containing 4.5% by weight on a SiO ₂ basis in a solution containing 20% by weight on a SiO ₂ basis on a fused silica particle (manufactured by Admatechs Co., Ltd., SO-E3; average particle diameter 1 μm) A solution obtained by adding 10% by weight to the weight of the above was placed in a pressure-resistant container such as an autoclave, hydrothermally treated at 200 ° C. for 16 hours, cooled to room temperature, and extracted.
The obtained liquid mixture was filtered with a quantitative filter paper (No. 5C, manufactured by Advantech Co., Ltd.) using a Buchner funnel (3.2 L, manufactured by Sekiya Rika Glass Instrument Co., Ltd.), then repeatedly washed, and surface-sealed. A cake-like substance composed of an aggregate of silica-based particles was obtained.
Subsequently, it dried and heat-processed at 120 degreeC for 24 hours with the dryer, and prepared the silica type particle (9).
The average particle diameter, the true density of the particles, the porosity, the moisture absorption rate, and the compressive strength of the obtained silica-based particles (9) were measured, and the results are shown in Table 1.

[Preparation of composition and base material and evaluation of physical properties before and after durability test]
Compositions and substrates were prepared from the silica-based particles (1) to (9) obtained in Examples 1 to 6 and Comparative Examples 1 to 3 using the method described in [Measuring method] (9). . Thereafter, physical properties were evaluated before and after the durability test, and the results are shown in Table 2.

Claims (12)

A silica-based particle having a void inside a nonporous outer shell silica layer, having a porosity in a range of 20 to 95% by volume and an average particle diameter in a range of 0.1 to 50 µm.
  The silica-based particle according to claim 1, wherein the silica-based particle has a negative pressure.   The silica-based particle according to claim 2, wherein the negative pressure of the cavity is 133 hPa or less. The silica-based particles according to any one of claims 1 to 3, wherein the compression strength of the silica-based particles is in the range of 0.1 to 200 kgf / mm ² . 5. The moisture absorption rate (weight change rate) when the silica-based particles are allowed to stand for 7 days in an air atmosphere at a temperature of 25 ° C. and a humidity of 90% is 0.1% or less. Silica-based particles.
6. The method for producing silica-based particles according to claim 1, wherein the following steps (a) to (d) are sequentially performed.
(A) Step of preparing silica-based particle precursor particles by spray drying an alkali silicate aqueous solution in a hot air stream (b) Step of immersing silica-based particle precursor particles in an acid aqueous solution to remove alkali (c) Water Heat treatment step (d) Drying and heat treatment step The method for producing silica-based particles according to claim 6, wherein the following step (c ') is carried out between the step (b) and the step (c).
(C ′) Drying / heating process The method for producing silica-based particles according to claim 6 or 7, wherein the hydrothermal treatment temperature in step (c) is 180 to 350 ° C.
  The resin composition for semiconductor sealing containing the silica-type particle in any one of Claims 1-5, and a thermosetting resin. When the volume of the silica-based particles is represented by A and the volume of the thermosetting resin is represented by B, the volume ratio (A / B) is in the range of 10/100 to 95/100. The resin composition for semiconductor encapsulation according to claim 9.
  The base material in which the coating film which consists of a resin composition of Claim 9 or 10 was formed.   In the high-temperature and high-humidity durability test (temperature 80 ° C., humidity 80%, holding time 1000 hours), the substrate has a relative dielectric constant change (Δε) of 0.2 or less using the resonance method before and after the test. Furthermore, the base material of Claim 11 whose variation | change_quantity ((DELTA) tan (delta)) of a dielectric loss tangent is 0.01 or less.