JP2001158614A - Spherical inorganic powder and its use - Google Patents

Abstract

[PROBLEMS] An epoxy resin having characteristics of low thermal expansion, high fracture toughness, high bending strength, resistance to solder reflow, low wear of a mold, and even in a high filling region of a filler. The present invention provides a spherical inorganic powder and a resin composition for semiconductor encapsulation, which can greatly improve the fluidity of the encapsulant regardless of the type of the resin. In the frequency particle size distribution, a region of 20 to 70 μm, a region of 3.0 to 10 μm, and a region of 0.20 to 1.0 μm
A spherical inorganic powder having a maximum value in the region of A resin composition for encapsulating a semiconductor, comprising: an epoxy resin; an epoxy resin; a curing agent for the epoxy resin; and the spherical inorganic powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a spherical inorganic powder and its use.

[0002]

2. Description of the Related Art In recent years, in the semiconductor industry, as semiconductors have become more highly integrated, semiconductor chips have become larger, wirings have been miniaturized, and multilayers have been developed. As for the mounting method, surface mounting suitable for high-density mounting on wiring boards and the like is becoming mainstream. With the progress of this mounting method, there is a demand for a higher performance of a sealing material for a semiconductor chip, particularly functions such as electric insulation and a low coefficient of expansion. In order to satisfy these requirements, a sealing material in which a synthetic resin, particularly an epoxy resin, is filled with melt-processed inorganic particles, particularly fused silica particles, as a filler is generally used. In recent years, nearly 90% of all semiconductor products have been resin-sealed due to improvements in the reliability of sealing resins and the performance and reliability of fused silica particles. It is desirable that the inorganic particles to be filled into the resin encapsulation be highly filled in the encapsulating resin from the viewpoints of electrical insulation, reduction in thermal expansion coefficient, and improvement in mechanical strength. Conventionally, angular inorganic particles obtained by mechanically crushing large silica stones have been used, but due to the development of the manufacturing method, spherical inorganic particles have been developed and can be filled higher than before. In addition, spherical inorganic particles have been awarded at present because they can also be made excellent in fluidity and mold wear resistance during sealing.

[0003] Such spherical inorganic particles include, for example, a method in which metal fine particles are thrown into a flame to cause oxidization reaction to form spherical particles, a method in which metal alcoholate is precipitated by a sol-gel method under specific conditions, and a method in which spherical particles are formed. Of the oxide powder in a pulverizer to form a pseudo-spherical shape, a method of melting or softening an oxide powder in a high-temperature flame to obtain a spherical shape.

[0004]

However, when the resin composition is filled with a high amount of filler, the flowability of the encapsulant is reduced even with spherical inorganic particles, causing various molding defects. There is.

Therefore, as a technique for preventing the moldability (fluidity) at the time of sealing in a high filling region of the filler from being impaired, for example, the gradient of a straight line represented by a rosin-Rammler diagram is set to 0.6 to 0. 95 and a method of widening the particle size distribution (Japanese Patent Laid-Open No. 6-80863);
To 1.0, and a method for further increasing the sphericity (Japanese Unexamined Patent Publication No.
No. 66151), and a method of adding a small amount of spherical fine powder having an average particle diameter of about 0.1 to 1 μm in order to enhance the fluidity of the sealing material (JP-A-5-239321) has been proposed. .

Among these, the method of adding a small amount of the spherical fine powder has a problem in that the flow characteristics and the burr characteristics of the resin composition for semiconductor encapsulation (hereinafter, also referred to as “encapsulant”) are high even in the high filling region of the filler. It has recently been receiving attention because it can be dramatically improved. The present inventors have developed fine particles that can dramatically improve the fluidity and burr characteristics of a sealing material by adding a small amount to a base filler regardless of the type of resin. However, since the addition of the fine particles depends on the fluidity of the base filler, the design of the base filler is important. In particular, from the viewpoint of mechanical strength, a filler filling rate of 90% or more is desired for the sealing material, but there is still no filler that can maintain high fluidity at the time of high filling even when fine particles are added. .

[0007] The present invention has been made in view of the above, and as a result of examining the effects on the filling amount and the fluidity of the sealing resin composition by focusing on the particle size of each particle in the filler, A filler made of a spherical inorganic powder having a particle size distribution of, has been developed, and the encapsulant using the same has greatly improved moldability at the time of high filling of 90% or more, and furthermore, regardless of the type of resin. It has been found that the same behavior is exhibited, which has led to the present invention.

That is, the present invention is as follows. (Claim 1) In the frequency particle size distribution, 20 to 70 μm
Area, 3.0 to 10 μm area, 0.20 to 1.0 μm
A spherical inorganic powder having a maximum value in a region of m. (Claim 2) The ratio of the frequency value of the maximum value in the region of 20 to 70 μm to the frequency value of the maximum value in the region of 3.0 to 10 μm (frequency value of the maximum value in the region of 20 to 70 μm / 3.0 to 1)
2. The spherical inorganic powder according to claim 1, wherein the maximum value (frequency value in a region of 0 μm) is 1 to 2. 3. (Claim 3) The spherical inorganic powder according to claim 1 or 2, wherein the spherical inorganic powder is amorphous silica. (Claim 4) Epoxy resin, curing agent for epoxy resin,
A resin composition for encapsulating a semiconductor, comprising the spherical inorganic powder according to claim 3.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

When the spherical inorganic powder of the present invention is used as a filler for a resin composition, particularly for a sealing material, it can be highly filled and can exhibit high fluidity. In other words, the spherical inorganic powder of the present invention has a specific property, and the sealing material to which the spherical inorganic powder is applied can satisfy the high fluidity that cannot be obtained in the high filling region, and adjust the resin composition. In this case, the degree of freedom can be increased.

The spherical inorganic powder of the present invention has local maximum values in the frequency particle size distribution in each of a region of 20 to 70 μm, a region of 3.0 to 10 μm, and a region of 0.20 to 1.0 μm. Spherical inorganic powders designed to have a maximum value in these regions have not existed so far, and it is possible to have a maximum value in all of these regions. Is very important in ensuring excellent moldability.

The particle component contained in the maximum value of 20 to 70 μm is a particle component serving as a nucleus at the time of filling. If the particle size is less than 20 μm, the moldability is significantly reduced, and if it exceeds 70 μm, chip damage occurs during molding. In addition, problems such as clogging of the mold gate may occur. In particular, it is preferably in the range of 30 to 50 μm. It is actually difficult to adjust the inorganic powder having a single particle size, but by setting the maximum value in the range of 30 to 60 μm, even if the particle size of the particles has a certain width from the maximum value, The powder can be easily prepared without mixing particles having a particle size of less than 20 μm or more than 70 μm. Further, the particle component contained in the maximum value of 3.0 to 10 μm can pass between the particles contained in the maximum value having a large particle diameter, thereby enabling high filling. In particular, when the particle size is about 0.1 to 0.2 times the maximum value of the large particle diameter of 20 to 70 μm, higher packing becomes possible, and it is particularly preferably 4.0 to 8.0 μm. By having these two maximum values at the same time, it is possible to achieve an unprecedented high fluidity at the time of filling with a high filler.

On the other hand, the particle component contained in the maximum value of 0.20 to 1.0 μm has a maximum value of 20 to 70 μm and 3.0 to 3.0 μm.
Since it is possible to fill the gap between the particles filled with particles having a maximum value of 10 μm, the closest packing in the spherical inorganic filler is improved, and the fluidity and burr characteristics of the resin composition, particularly the sealing material, are significantly improved. it can.

The composition ratio of the particle component in the range of 0.20 to 1.0 μm is desirably 5 to 30%, particularly 7 to 15% in the spherical inorganic powder of the present invention. It can be achieved more effectively.

Further, the particle size of the particle size distribution of the spherical inorganic powder of the present invention is converted into a logarithm, and the particle size width is log (μm).
= 20 to 70 when the histogram is displayed with a width of 0.04
Of the two maximum values in the region of μm and 3.0 to 10 μm, the maximum value of the region of 20 to 70 μm is represented by H1, 3.0 to 3.0 μm.
The maximum value of 10 μm is defined as H2, and the ratio of the frequency values of H1 and H2 is preferably in the range of 1 to 2, particularly 1 to 1.5. When the ratio is less than 1 or more than 2, the viscosity of the resin composition, particularly the sealing material, increases and the fluidity decreases.

The particle size characteristics of the spherical inorganic powder of the present invention are values based on a particle size measurement method by a laser scattering light method, and were measured by a Coulter particle size analyzer (Model LS-230; manufactured by Coulter Corporation).

"Spherical" in the spherical inorganic powder of the present invention
It is preferable that the value expressed by the roundness is 0.90 or more. The roundness was measured using a scanning electron microscope (“JSM-T200” manufactured by JEOL Ltd.) and an image analyzer (manufactured by Nippon Avionics). First, the projected area (A) and the perimeter (PM) of the particles are measured from the SEM photograph of the powder. If the area of a perfect circle corresponding to the perimeter (PM) is (B), the perfectness of the particle can be displayed as A / B.

Then, assuming a perfect circle having the same perimeter as the perimeter (PM) of the sample particles, PM = 2πr, B =
Since πr ² , B = π × (PM / 2π) ² ,
The roundness of each particle is: Roundness = A / B = A × 4π /
(PM) Calculated as ² . 10 obtained in this way
The roundness of zero or more particles is determined and the average value is defined as the average sphericity.

The spherical inorganic powder to which the present invention is directed is a simple substance such as silica, alumina, titania, or a composite material containing them, but when the use of the present invention is a sealant, amorphous silica is used. Is particularly preferred. By using amorphous silica, there is an advantage that the properties of low thermal expansion, high fracture toughness, high bending strength, solder reflow resistance, and low wear of the mold can be highly exhibited.

The spherical inorganic powder of the present invention can be used by being contained in a resin composition at 90% or more. When the use of the spherical inorganic powder of the present invention is a sealing material,
When (A) an epoxy resin, (B) a curing agent for an epoxy resin, and (C) the spherical inorganic powder of the present invention, (A)
The content is preferably from 80 to 95% based on the total amount of (B) and (C). In particular, when the content is 90 to 95%, the effect of the spherical inorganic powder of the present invention is remarkable. (C)
When the proportion of the component is less than 80%, the fracture toughness value and the bending strength of the resin composition, particularly the sealing material, decrease, and the water absorption rate increases and the solder reflow resistance decreases. On the other hand, 95
%, It becomes difficult to maintain good fluidity, and there is a risk that moldability will deteriorate.

The resins used in the present invention include epoxy resins, silicone resins, phenolic resins, melamine resins, urea resins, unsaturated polyesters, fluorine resins, polyamides such as polyimide, polyamideimide and polyetherimide, and polybutylene terephthalate. , Polyester such as polyethylene terephthalate, polyphenylene sulfide, wholly aromatic polyester, polysulfone, liquid crystal polymer, polyether sulfone, polycarbonate,
Maleimide modified resin, ABS resin, AAS (acrylonitrile acrylic rubber / styrene) resin, AES (acrylonitrile / ethylene / propylene / diene rubber-styrene) resin and the like can be mentioned.

Among these, as the resin for the sealing material, an epoxy resin having two or more epoxy groups in one molecule is preferable. Specific examples thereof include phenol novolak type epoxy resin, orthocresol novolak type epoxy resin, epoxidized novolak resin of phenols and aldehydes, glycidyl ethers such as bisphenol A, bisphenol F and bisphenol S,
Glycidyl ester acid epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, alkyl-modified polyfunctional obtained by reaction of polybasic acid such as phthalic acid and dimer acid with epochlorohydrin Epoxy resin, β-naphthol novolak type eoxy resin,
1,6-dihydroxynaphthalene type epoxy resin, 2,
Examples thereof include a 7-dihydroxynaphthalene type epoxy resin, a bishydroxybiphenyl type epoxy resin, and an epoxy resin into which halogen such as bromine is introduced for imparting flame retardancy. Among them, orthocresol novolak type epoxy resin, bishydroxybiphenyl type epoxy resin, naphthalene skeleton epoxy resin and the like are preferable from the viewpoint of moisture resistance and solder reflow resistance.

The curing agent for the epoxy resin is not particularly limited as long as it cures by reacting with the epoxy resin. For example, phenol, cresol, xylenol,
Novolak type obtained by reacting one or a mixture of two or more selected from the group of resorcinol, chlorophenol, t-butylphenol, nonylphenol, isopropylphenol, octylphenol and the like with formaldehyde, paraformaldehyde or paraxylene under an oxidation catalyst. Resin, polyparahydroxystyrene resin, bisphenol compounds such as bisphenol A and bisphenol S, trifunctional phenols such as pyrogallol and phloroglucinol, acid anhydrides such as maleic anhydride, phthalic anhydride and pyromellitic anhydride, and metaphenylene Examples thereof include aromatic amines such as diamine, diaminodiphenylmethane, and diaminodiphenylsulfone.

The following components can be added to the resin composition for semiconductor encapsulation of the present invention as required. That is, as a low stress agent, silicone rubber, polysulfide rubber, acrylic rubber, butadiene rubber, rubber-like substances such as styrene block copolymers and saturated elastomers, various thermoplastic resins, silicone resins, etc. Γ-glycidoxy as a silane coupling agent such as a resinous substance, and a resin obtained by modifying part or all of an epoxy resin or a phenol resin with aminosilicon, epoxysilicon, alkoxysilicon or the like. Epoxysilanes such as propyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, aminosilanes such as aminopropyltriethoxysilane, ureidopropyltriethoxysilane, N-phenylaminopropyltrimethoxysilane, and phenyltriphenyl Methoxysilane, methyltri Silane, such as hydrophobic silane compounds and mercapto silane and octadecyl trimethoxy silane, as a surface treatment agent, Zr chelate - DOO, titanate - DOO coupling agents, aluminum-based coupling agent, a flame retardant aid, Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O _5, etc., flame retardants such as halogenated epoxy resins and phosphorus compounds, and coloring agents such as carbon black, iron oxide, dyes,
Pigments and the like. Further, a release agent such as wax can be added. Specific examples thereof include natural waxes, synthetic waxes, metal salts of straight-chain fatty acids, acid amides, esters, and paraffin.

In particular, when high moisture resistance reliability and high-temperature storage stability are required, addition of various ion trapping agents is effective. Specific examples of the ion trapping agent include Kyowa Chemical's trade names “DHF-4A”, “KW-2000”,
"KW-2100" and "I
XE-600 ".

The resin composition for encapsulating a semiconductor of the present invention may contain a curing accelerator for accelerating the reaction between the epoxy resin and a curing agent for the epoxy resin. As the curing accelerator, 1,8-diazabicyclo (5,4,
0) Undecene-7, triphenylphosphine, benzyldimethylamine, 2-methylimidazole and the like.

The resin composition for encapsulating a semiconductor of the present invention is prepared by mixing the above-mentioned materials with a blender or a mixer,
It can be manufactured by melt-kneading with a screw, kneader, single- or twin-screw extruder, Banbury mixer, etc., and pulverizing after cooling.

To encapsulate a semiconductor using the resin composition for semiconductor encapsulation of the present invention, transfer molding,
A known molding method such as a multi-plunger may be adopted, which can impart properties such as heat resistance, strength, moisture resistance, and heat conduction. The property becomes good.

[0029]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

Examples 1 to 7 Comparative Examples 1 to 9 The apparatus shown in FIG. 1, that is, the burner 2 to which the fuel gas supply pipe 3, the auxiliary combustion gas supply pipe 4, and the inorganic raw material powder supply pipe 5 are connected is a melting furnace. A spherical siliceous powder was produced as a spherical inorganic powder by using an apparatus installed on the top of Sample No. 1. In order to use the calorie efficiently, four burners are installed in the same furnace, the raw material is sprayed from each burner, and spheroidization is performed in the melting furnace. The spherical inorganic powder having a desired particle size is connected in series so that the spherical powder discharged from the melting furnace is pneumatically transported to a collection system including a gravity settling chamber 6, a cyclone 7, a bag filter 8, and a blower 9. Can be collected with a bag filter using two types of classification devices, a gravity sedimentation chamber and a cyclone.

The spherical inorganic powder has a particle diameter of 1 to 100 μm.
Was produced as follows using the natural silica powder of the above. The raw material was transported to each burner using oxygen as a carrier gas. Each burner formed a flame with the fuel gas (LPG) and the auxiliary gas (oxygen), and spheroidized by injecting the raw material powder into the flame at various supply amounts. At the same time as adjusting the average sphericity by changing the flame formation conditions and the raw material supply amount, classification was performed to produce eight kinds of powders having a single maximum value shown in Table 1. The powders were mixed at various ratios shown in Tables 2 and 3 to produce powders A to Q. In these powders, an area of 20 to 70 μm, 3.0 to
The maximum values in the region of 10 μm and in the region of 0.20 to 1.0 μm are shown in the table as H1, H2, and H3, respectively.
The roundness of these powders A to Q was all 0.90 or more.

Next, the fluidity promoting effect when powders A to Q were blended with a sealing material was evaluated according to the following. Table 2 shows the results of the examples, and Table 3 shows the results of the comparative examples.

Fluidity promoting effect test After powders A to Q were dry-blended with each material in the composition shown in Table 4, they were kneaded, cooled and pulverized for 5 minutes using a mixing roll having a roll surface temperature of 100 ° C. The spiral flow was measured. The measurement was carried out using a spiral flow mold and EMMI-66 (Epoxy Mold).
ing Material Institute;
Society of Plastic Indust
ry). The molding temperature is 175 ° C., the molding pressure is 7.5 MPa, and the molding time is 90 seconds. The burr was measured using a burr measurement mold having slits of 2 μm, 5 μm, 10 μm, and 30 μm, and the molding temperature was 175 μm.
The resin flowing into the slits at a molding temperature of 7.5 ° C. and a molding pressure of 7.5 MPa was measured with calipers, and the values measured in the respective slits were averaged to obtain a burr length.

As is clear from the table, the sealing material containing the spherical inorganic powder of the present invention has a fluidity of 100 cm or more even when the filling rate of the spherical inorganic powder is 85%, and is 90% or less. %, It was shown to maintain a fluidity of 70 cm or more even with a high filling of at least 70%.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

[Table 4]

[0039]

According to the present invention, it has the characteristics of low thermal expansion, high fracture toughness, high bending strength, resistance to solder reflow, and low wear of the mold. Irrespective of the type of epoxy resin, a spherical inorganic powder and a sealing material capable of greatly improving the fluidity of the sealing material are provided.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus for producing a spherical inorganic powder.

[Description of Signs] 1 melting furnace 2 burner 3 fuel gas supply pipe 4 auxiliary combustion gas supply pipe 5 inorganic raw material powder supply pipe 6 gravity settling chamber 7 cyclone 8 bag filter 9 blower

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H01L 23/31 F term (reference) 4G072 AA25 BB07 DD03 DD04 GG02 HH20 JJ47 MM36 TT02 UU07 4J002 CC04X CD01W CD02W CD04W CD05W CD06W CD17W DJ016EJ EJ047 EL137 EL147 EN077 EV247 FD016 FD14X FD147 GQ05 4J036 AA01 AB11 AB13 AD07 AD08 AD20 AF05 AF06 AJ05 DA01 DB02 DB06 DB15 DB17 DC10 FA05 FB07 JA07 4M109 AA01 EA02 EB02 EB13 EB16

Claims (4)

[Claims] 1. In a frequency particle size distribution, 20 to 70 μm
Area, 3.0 to 10 μm area, 0.20 to 1.0 μm
A spherical inorganic powder having a maximum value in a region of m. 2. The ratio of the frequency of the local maximum in the region of 20 to 70 μm to the frequency of the local maximum in the region of 3.0 to 10 μm (the frequency of the local maximum in the region of 20 to 70 μm / 3.0 to 1).
2. The spherical inorganic powder according to claim 1, wherein the maximum value (frequency value in a region of 0 μm) is 1 to 2. 3. 3. The spherical inorganic powder according to claim 1, wherein the spherical inorganic powder is amorphous silica. 4. An epoxy resin, a curing agent for the epoxy resin,
A resin composition for encapsulating a semiconductor, comprising the spherical inorganic powder according to claim 3.