TWI411594B - Ceramic powder and its use - Google Patents

Abstract

This invention provides a ceramic powder for use in a semiconductor packaging material. The ceramic powder is mixed with a rubber or a resin in order for the preparation of composition which exhibits excellent property of filling a narrow gap and forming a molded article. The ceramic powder of this invention has a multiple peak occurrence frequency particle size distribution containing at least two peaks, wherein a first peak of maximum particle diameter is in the range of 12-30um, and a second peak of maximum particle diameter is in the range of 2-7um, and wherein the rate of contents of particles having particle diameter of from 7um to 12um is 18% (mass) or less (including 0%), and the ratio of the occurrence frequency value F2 of the maximum particle diameters of the second peak to the occurrence frequency value F1 of the maximum particle diameter of the first peak (F2/F1) is 0.5-1.3.

Description

Ceramic powder and its use

The present invention relates to ceramic powders and uses thereof.

In response to the demand for small size, light weight, and high performance of electronic equipment, the miniaturization, thinning, and high-density packaging of semiconductors are rapidly progressing. The semiconductor package structure is also transferred from the conventional QFP or SOP wire terminal type to facilitate the use. Area array type such as BGA or LGA for thinning and high density packaging. In addition, in recent years, a laminated wafer structure in which a plurality of IC wafers are stacked in one semiconductor package has been actively used, and the structure of the semiconductor package is complicated and the high-density packaging is progressing.

In the laminated wafer structure, several problems have become a focus in terms of the complexity of the structure and the formability. If the IC wafer is laminated, the difference between the packaged portion and the unencapsulated portion of the wafer on the substrate becomes extremely large compared to the case of the conventional single wafer, so that a flow velocity difference occurs in the semiconductor package material. On the other hand, in the narrow portion of the uppermost stage of the laminated wafer in which the flow velocity is slow, there is a problem that minute bubbles are caught and voids are generated. Further, the metal wires for electrical connection are increased in proportion to the number of wafers of the laminate, and in order to extend the life, the flow resistance at the time of packaging is deformed, and contact with adjacent wires is liable to occur. Short circuit problem.

In order to solve such problems, the improvement from the molding die side and the resin side and the filler side of the semiconductor package material is performed. For the improvement of the molding die side, for example, a method in which a vent hole is provided in a mold to prevent voids in the mold during molding (Patent Document 1); a flow control member is provided in the mold, and the air is suppressed. A method of generating pores and line deformation (Patent Document 2). The improvement from the side of the semiconductor encapsulating material is, for example, a method of reducing the viscosity of the resin and precisely controlling the curing time of the resin at the molding temperature (Patent Document 3); reducing the filling rate of the filler to the resin and reducing the encapsulation resin At the same time, the viscosity is increased, and the particle size of the filler is reduced, and the filling property of the slit portion is improved. The particle size distribution of the filler is adjusted to achieve a method in which the filling property and the low viscosity are simultaneously established (Patent Document 4). However, these methods are not sufficient, and there is still no semiconductor package material which satisfies the two characteristics required for the package of a stacked wafer structure semiconductor which does not cause voids or line deformation, and the ceramic powder used therefor.

[Patent Document 1] Japanese Laid-Open Patent Publication No. 2005-310831 (Patent Document 3) Japanese Laid-Open Patent Publication No. Hei. No. Hei. Bulletin

An object of the present invention is to provide a ceramic powder of a semiconductor encapsulating material having excellent slit filling properties and excellent moldability, and a composition comprising at least one of the resin and the rubber, in particular, a semiconductor package. material.

The ceramic powder of the present invention is characterized in that it has a multimodality frequency particle size distribution having at least two peaks in a particle size measured by a laser diffraction scattering type particle size distribution measuring machine; The maximum particle diameter is 12 to 30 μm, the maximum particle diameter of the second peak is in the range of 2 to 7 μm; the content of the particles exceeding 7 μm and less than 12 μm is 18% by mass or less (including 0%); The ratio (F2/F1) of the frequency value F2 of the radial path to the frequency value F1 of the maximum particle diameter of the first peak is 0.5 to 1.3.

In the present invention, it is preferred to provide at least one embodiment selected from the group consisting of (1) having a third peak and having a maximum particle diameter in the range of 0.1 to 0.8 μm; and (2) a sieve having a JIS standard of 53 μm. The measured amount of the sieve was 0.5% by mass or less; and (3) the ceramic powder was cerium oxide powder.

Further, the composition of the present invention is characterized in that the ceramic powder of the present invention is contained in at least one of a resin and a rubber. Furthermore, the semiconductor encapsulating material of the present invention is characterized in that the composition of the present invention is an epoxy resin composition.

According to the present invention, it is possible to maintain a high slit filling property even when the filling rate of the ceramic powder in the resin composition or the rubber composition is 89% by mass or more, and formability (it is difficult to generate voids and lines) Deformation) An excellent resin composition or rubber composition (hereinafter, referred to as "composition"), especially a semiconductor encapsulating material.

Hereinafter, the present invention will be described in detail.

The powder of the present invention is composed of a ceramic powder including, for example, ceria, or various ceramic powders such as alumina, titania, magnesia, tantalum nitride, aluminum nitride, and boron nitride.

These powders may be used singly or as a mixture of two or more types, but from the viewpoint of the thermal expansion ratio of the semiconductor element and the semiconductor package material, and the improvement of heat resistance, cold and heat cycle resistance, and low mold wear resistance. In particular, it is preferably a cerium oxide powder, and particularly preferably an amorphous cerium oxide produced by melting crystalline cerium oxide at a high temperature or an amorphous cerium oxide produced by a synthesis method. The amorphous ratio of the amorphous ceria powder is preferably 95% or more as measured by a method described later.

The ceramic powder of the present invention is characterized in that it has a multimodality frequency particle size distribution having at least two peaks in a particle size measured by a laser diffraction scattering particle size distribution measuring machine; the maximum particle diameter of the first peak is 12 to 30 μm, the maximum particle diameter of the second peak is in the range of 2 to 7 μm; the content of the particles exceeding 7 μm and less than 12 μm is 18% by mass or less (including 0%); and then, the second peak The ratio (F2/F1) of the frequency value F2 of the maximum particle diameter to the frequency value F1 of the maximum particle diameter of the first peak is 0.5 to 1.3. When the ceramic powder has such a characteristic, even if the filling ratio of the ceramic powder to the epoxy resin or the like is 89% by mass or more, a semiconductor encapsulating material which maintains high slit filling property and is excellent in moldability can be provided.

The particle group having the first peak of the maximum particle diameter in the range of 12 to 30 μm is the main particle of the ceramic powder of the present invention. When the maximum particle diameter is less than 12 μm, the viscosity of the composition sharply rises, and it becomes difficult to prepare a composition having high formability. On the other hand, when the maximum particle diameter exceeds 30 μm, the viscosity is lowered, but it is difficult for the particles to enter the narrow portion of the uppermost stage of the stacked wafer, and the gap filling property is deteriorated. The maximum particle size of the first peak is preferably in the range of 15 to 25 μm. Patent Document 4 is a ceramic powder having a multimodal particle size distribution in which the maximum peak diameter of the first peak is 32.2 to 42.3 μm, which is different from the present invention, and the content of the particles of 12 to 30 μm is preferably 25% by mass. The above is particularly preferably 35 mass% or more. The upper limit thereof is, for example, preferably 60% by mass.

The particle group having the second peak of the maximum particle diameter in the range of 2 to 7 μm enters the gap between the group of the first peaks to make the filling structure of the particles dense, so that the filling property of the ceramic powder is further improved. The viscosity of the composition is further reduced. It is preferably 3 to 6 μm. In particular, when the ratio (F2/F1) of the frequency value F2 of the maximum particle diameter of the second peak to the frequency value F1 of the maximum particle diameter of the first peak is 0.5 to 1.3 (preferably 0.6 to 1.2), a lower viscosity can be obtained. It can improve the formability. The value of F2/F1 of the ceramic powder having a multimodal particle size distribution shown in Patent Document 4 is estimated to be 1.9 or more. Further, the content of the particles of 2 to 7 μm is preferably 15% by mass or more, and particularly preferably 20% by mass or more. The upper limit is, for example, preferably 50% by mass.

In the present invention, particles exceeding 7 μm and less than 12 μm are not required in the dense filling structure composed of the two peaks or the group of three peaks described later, and therefore are not contained (0%). For the most appropriate. Even if it is contained, the content is at most 18% by mass (including 0%), and even 15% by mass (including 0%) is preferable. A particle of more than 7 μm and less than 12 μm means a depth of a valley composed of a first peak and a second peak, and a portion of the valley is preferably a particle. This condition is extremely important, and the ceramic powder which controls the content of particles exceeding 7 μm and less than 12 μm has never been seen before.

In the present invention, further, a particle group having a third peak having an extremely large particle diameter in the range of 0.1 to 0.8 μm (preferably 0.2 to 0.7) is more preferable. This particle group enters the gap between the filling structure of the particles composed of the first peak particle group and the second peak particle group, and the filling structure is made denser. Therefore, even if a higher filling ratio is formed, good formability is maintained. Therefore, it is possible to modulate a composition having few voids or line distortion and excellent properties. The content of the particles falling within this range is generally preferably 3% by mass or more, and particularly preferably 10% by mass or more. The upper limit is, for example, preferably 25% by mass.

The amount of the sieve of the ceramic powder of the present invention measured by a JIS standard sieve of 53 μm is preferably 0.5% by mass or less (including 0%). More preferably, the amount of the sieve is 0.3% by mass or less (including 0%). When the amount of the sieve exceeds 0.5% by mass, the gap filling property tends to deteriorate.

The average sphericity of the ceramic powder of the present invention is preferably 0.85 or more, more preferably 0.90 or more. Thereby, the gap filling property can be improved and the viscosity of the composition can be further reduced.

The particle size distribution of the ceramic powder of the present invention is based on the value determined by the particle size of the laser diffraction scattering method. The particle size distribution measuring apparatus is, for example, "Model LS-230" manufactured by Beckman Coulter Co., Ltd. (the particle diameter channel is a log (μm) = 0.04 width). In the measurement, water was used as a solvent, and the pretreatment was carried out for 1 minute, and the homogenizer was used and the output power of 200 W was used for dispersion treatment. Further, the concentration of PIDS (Polarization Intensity Differential Scattering) was adjusted to 45 to 55% by mass. The refractive index of water is 1.33, and the refractive index of the sample powder is based on the refractive index of the material. For example, in amorphous ceria, the refractive index is made 1.50.

The maximum particle diameter refers to the center value of the particle range indicating the maximum value in the frequency particle size distribution obtained by the laser diffraction scattering method. For example, in the cumulative particle size distribution, when the cumulative value up to 20 μm is 50% by mass until the cumulative value of 24 μm is 65 mass%, and the cumulative value of 28 μm is 70% by mass, the particle range indicating the maximum value is Between 20 and 24 μm, the polar particle diameter is calculated as the center of 20 μm and 24 μm, or 22 μm.

The amount of the ceramic powder of the present invention can be measured using a JIS standard sieve. 10 g of the ceramic powder of the fine scale was placed in a standard sieve of JIS size, and the powder was shaken for 5 minutes while spraying water, and the ceramic powder remaining on the sieve was collected in a metal container, and after drying, the mass was measured. The amount of ceramic powder remaining on the sieve was divided by the mass supplied to the measured ceramic powder to form a percentage, and the amount of the sieve was calculated.

The amorphous ratio is analyzed by X-ray diffraction using a powder X-ray diffraction apparatus (for example, the product name "Mini Flex" manufactured by RIGAKU Co., Ltd.) in the range of 26 ° to 27.5 ° of the CuK α line. The intensity ratio of the specific diffraction peak is measured. For example, in the case of cerium oxide powder, the crystalline cerium oxide has a main peak at 26.7°, but there is no peak in the case of amorphous cerium oxide. If the amorphous cerium oxide is mixed with the crystalline cerium oxide, a peak height of 26.7° according to the ratio of the crystalline cerium oxide can be obtained, so the X-ray intensity from the sample is X for the crystalline cerium oxide standard sample. The ratio of the line strength is calculated from the crystal cerium oxide mixing ratio (X-ray diffraction intensity of the sample/X-ray diffraction intensity of the crystalline cerium oxide), from the formula: amorphous ratio (%) = (1-crystallization The mass ratio of the cerium oxide mixture was ×100 to determine the amorphous ratio.

The average sphericity is obtained by taking in an image analysis device (for example, the product name "Mac View" manufactured by Mountech Co., Ltd.), which is imaged by a solid microscope (for example, the product name "Model SMZ-10" manufactured by Nikon Corporation). The photograph was measured from the projected area (A) of the particles and the surrounding length (PM). If the area corresponding to the true circle of the surrounding length (PM) is (B), the true roundness of the particles becomes A/B, so it is assumed to have a circumference that is the same as the circumference (PM) of the sample. True circle, because PM=2 π r, B=π r ² , so B=π×(PM/2 π) ² , the roundness of each particle becomes true roundness=A/B=A×4 π/(PM) ² . The true roundness of 200 particles of any of the particles thus obtained was determined, and the square of the average value was taken as the average sphericity.

The ceramic powder of the present invention can be easily produced by mixing, for example, particles having an average particle diameter of 0.1 to 0.8 μm, particles of 2 to 7 μm, and particles of 12 to 30 μm. In addition, when the ceramic powder is a spherical oxide powder such as spherical cerium oxide powder or spherical alumina powder, the powder raw material is sprayed in a high-temperature flame, and after being subjected to a melt spheroidization treatment, for example, a weight precipitation chamber or a cyclone In the method of recovering a collecting device such as a cyclone, a bag filter, or an electric dust collector, the processing conditions such as the particle size, the amount of the spray, the flame temperature, and the like of the powder raw material may be appropriately changed, or the recovered powder may be classified, sieved, or the like. Mixing or the like, or by using both.

The composition of the present invention contains the ceramic powder of the present invention in at least one of a resin and a rubber. The content of the ceramic powder in the composition is, for example, preferably from 10 to 99% by mass, more preferably from 30 to 95% by mass.

The resin may be an epoxy resin, or a silicone resin, a phenol resin, a melamine resin, a urea resin, an unsaturated polyester, a fluororesin, a polyimine, a polyamidimide, or a polyether. Polyamides such as amines, polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, wholly aromatic polyester, polyfluorene, liquid crystal polymer, poly Ether oxime, polycarbonate, maleic imine modified resin, ABS resin, AAS (acrylonitrile-acrylic rubber/styrene) resin, AES (acrylonitrile/ethylene/propylene/diene rubber-styrene) resin, etc. .

Among these, the semiconductor encapsulating material is preferably an epoxy resin having two or more epoxy groups in one molecule. To be exemplified, it is a phenol novolac type epoxy resin, an o-cresol novolak type epoxy resin, and an epoxidized phenolic and aldehyde novolak resin; bisphenol A, bisphenol F and glycidyl ether such as bisphenol S; glycidyl ester epoxy resin obtained by reaction of polybasic acid such as capric acid or dimer acid with epichlorohydrin; linear aliphatic epoxy resin; Alicyclic epoxy resin, heterocyclic epoxy resin, alkyl modified polyfunctional epoxy resin, β-naphthol novolak epoxy resin, 1,6-dihydroxynaphthalene epoxy resin, 2,7 A dihydroxy naphthalene type epoxy resin, a bishydroxybiphenyl type epoxy resin, or an epoxy resin which introduces a halogen such as bromine to impart flame resistance. Among them, in terms of moisture resistance or solder flow resistance, it is preferably an o-cresol novolac type epoxy resin, a bishydroxybiphenyl type epoxy resin, or a naphthalene skeleton epoxy resin.

Examples of the curing agent for the epoxy resin include, for example, phenol, or cresol, xylenol, resorcin, chlorophenol, t-butylphenol, nonylphenol, isopropylphenol, octylphenol, and the like. A novolac type resin or a poly(p-hydroxystyrene resin) obtained by reacting one or a mixture of two or more of them in a group with formaldehyde, paraformaldehyde or paraxylene under an oxidation catalyst. a bisphenol compound such as bisphenol A or bisphenol S; a trifunctional phenol such as pyrogallol or phloroglucin; maleic anhydride, phthalic anhydride or pyromellitic anhydride; An acid anhydride; an aromatic amine such as m-phenylenediamine, diaminodiphenylmethane or diaminodiphenylphosphonium. In order to promote the reaction of the epoxy resin with the hardener, a hardening accelerator such as triphenylphosphine or 1,8-difluorene-bicyclo(5,4,0)undecene-7 described above can be used.

In the composition of the present invention, the following components can be further formulated as needed. That is, the low-stressing agent is a rubber-like substance such as polyoxymethylene rubber, polysulfide rubber, acrylic rubber, butadiene rubber, styrene block copolymer or saturated elastomer, various thermoplastic resins, polyoxyl a resinous substance such as a resin, or a resin obtained by partially or completely modifying one or all of an epoxy resin or a phenol resin with an amine polyphosphoric acid, an epoxy polyoxyxylene, an alkoxy polyoxygen or the like; a decane coupling agent; Ethylene decane such as γ-glycidoxypropyltrimethoxydecane or β-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, aminopropyltriethoxydecane, Amino decane such as ureidopropyltriethoxy decane or N-phenylaminopropyltrimethoxydecane, phenyltrimethoxynonane, methyltrimethoxydecane, octadecyltrimethoxydecane, etc. a hydrophobic decane compound or a thiosulfan oxane; a surface treatment agent: a Zr chelating agent, a titanate coupling agent, an aluminum coupling agent, etc.; and a flame resistant auxiliary system such as Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O _{5 ,} etc. The flame retardant is a halogenated epoxy resin or a phosphorus compound; the colorant is carbon black, iron oxide, dye, and pigment And the like; Furthermore, the release agent-based natural waxes, synthetic waxes, metal salts of linear fatty acid acyl amine, ester, paraffin and the like.

The composition of the present invention may be such that a predetermined amount of each of the above materials is blended by a blender or a Hanschel mixer, etc., and then heated rolls, kneaders, uniaxial or biaxial extruders After the kneader is cooled, it is pulverized and produced.

The semiconductor encapsulating material of the present invention is a composition of the present invention which is composed of an epoxy resin composition. The semiconductor package is encapsulated using the semiconductor package material of the present invention by a conventional molding method such as transfer molding or multi-plunger.

[Examples] Examples 1 to 5 and Comparative Examples 1 to 7

By using the apparatus described in the examples of JP-A-2001-233627, a raw material composed of a powder of natural vermiculite is supplied to a flame formed by burning LPG and oxygen, and is subjected to melt spheroidization treatment. A spherical amorphous ceria powder was produced. Twelve kinds of spherical amorphous ceria powders A to L shown in Table 1 were produced by adjusting flame forming conditions, raw material particle size, raw material supply amount, classification conditions, and the like. The adjustment of the ratio of the particle diameter of the particle diameter exceeding 7 μm to less than 12 μm, the frequency value F2 of the maximum particle diameter of the second peak, and the frequency value F1 of the maximum particle diameter of the first peak (F2/F1) The operation conditions of changing the particle size of the raw material, the multi-stage sieve separation of the spheroidized powder, and the mixing amount of the coarse particles, the fine particles, and the ultrafine particles recovered by the sieve separation operation are carried out. The control of the average sphericity is performed by adjusting the flame temperature and the amount of raw material supplied.

The amorphous ratio of the spherical amorphous ceria powders A to L is 99.5% or more, and the average sphericity is 0.85 or more. The particle size distribution of the powders is measured to determine the maximum particle diameter, the particle content of more than 7 μm and less than 12 μm, the frequency value F2 of the maximum particle diameter of the second peak, and the frequency value F1 of the maximum particle diameter of the first peak. Ratio (F2/F1). The maximum particle diameters in the range of 12 to 30 μm, the range of 2 to 7 μm, and the range of 0.1 to 0.8 μm are represented as P1, P2, and P3, respectively, and are shown in Table 1.

In order to evaluate the characteristics of the semiconductor encapsulating material as the obtained spherical amorphous ceria powder, for the spherical amorphous ceria powder A to L 89 parts (parts by mass, the same applies hereinafter), 4, 4' is added. - 5.5 parts of bis(2,3-epoxypropoxy)-3,3',5,5'-tetramethylbiphenyl type epoxy resin, 4.0 parts of phenol resin, 0.2 part of triphenylphosphine, γ - 0.5 parts of glycidoxypropyltrimethoxydecane, 0.3 parts of carbon black, 0.5 parts of carnauba wax, dry blending with a Hanschel mixer, and biaxial extrusion in the same direction The kneading machine (screw diameter D = 25 mm, kneading disc length 10 Dmm, paddle rotation number 150 rpm, discharge amount 5 kg / h, heating temperature 105 to 110 ° C) was heated and kneaded. After the kneaded material (spit material) was cooled by a cold press, it was pulverized to produce a semiconductor encapsulating material, and the fluidity, the slit filling property, and the amount of gold wire deformation were evaluated as follows. The results of these are shown in Table 1.

(1) Fluidity/Spiral Flow A transfer molding machine is used which is equipped with a mold for measuring a spiral flow according to EMMI-I-66 (Epoxy Molding Material Institute: Society of Plastic Industry). Spiral flow value. The transfer molding conditions were a mold temperature of 175 ° C, a forming pressure of 7.4 MPa, and a dwell time of 90 seconds.

(2) Slit-filling property: A die-bonding film (Die Attach Film) is attached to a BGA substrate substrate, and two wafers having a wafer size of 8 mm × 8 mm × 0.3 mm are stacked, and after the gold wires are connected, the above semiconductors are used. The package material was formed into a package size of 38 mm × 38 mm × 1.0 mm by a transfer molding machine, and then post-hardened at 175 ° C for 8 hours to prepare 30 BGA analog semiconductors. Further, the gap on the wafer was 200 μm, the diameter of the gold wire was ψ 30 μm, and the average length was 5 mm. The transfer molding conditions were a mold temperature of 175 ° C, a forming pressure of 7.4 MPa, and a dwell time of 90 seconds. The 30 analog semiconductors were visually judged for the presence or absence of unfilling, and the unfilled analog semiconductor system used an ultrasonic flaw detector to measure the number of voids and calculate the average number of holes per one of the analog semiconductors.

(3) The amount of gold wire deformation The portion of the gold wire of the analog semiconductor was observed by a soft X-ray transmission device, and the amount of deformation of the gold wire was measured. The amount of gold wire deformation refers to the maximum distance of the gold line movement before and after the package, and the average value of 12 gold wires is obtained.

As is apparent from the comparison between the examples and the comparative examples, according to the ceramic powder of the present invention, a composition having more excellent slit filling properties and moldability than the comparative example, in particular, a semiconductor encapsulating material can be prepared.

[Industrial Applicability]

The ceramic powder of the present invention can be used as a laminate for semiconductor packaging materials used in automobiles, portable electronic devices, personal computers, home electric products, and the like, and can be used as a putty and a seal. Filling materials such as sealing materials, various rubbers, and various engineering plastics. Further, the composition of the present invention can be used as a prepreg for a printed circuit board, for example, as a semiconductor packaging material, and can be used as a glass woven fabric, a glass nonwoven fabric, or other organic substrate. Various engineering plastics, etc.

Claims (6)

A ceramic powder characterized by having a multimodality frequency particle size distribution having at least two peaks in a particle size measured by a laser diffraction scattering particle size distribution measuring machine; The particle diameter is 12 to 30 μm, the maximum particle diameter of the second peak is in the range of 2 to 7 μm, and the content of the particles exceeding 7 μm and less than 12 μm is 18% by mass or less (including 0%); the maximum particle diameter of the second peak The ratio of the frequency value F2 to the frequency value F1 of the maximum particle diameter of the first peak (F2/F1) is 0.5 to 1.3, the particle content of 12 to 30 μm is 25 to 60% by mass, and the particle content ratio of 2 to 7 μm. 15 to 50% by mass. The ceramic powder according to claim 1, wherein the compound has a third peak, and the maximum particle diameter is in the range of 0.1 to 0.8 μm, and the particle content of 0.1 to 0.8 μm is 3 to 25% by mass. The ceramic powder according to claim 1 or 2, wherein the amount of the sieve measured by a JIS standard sieve of 53 μm is 0.5% by mass or less (including 0%). The ceramic powder according to claim 1 or 2, wherein the ceramic powder is cerium oxide powder. A composition comprising the ceramic powder according to any one of claims 1 to 4 in at least one of a resin and a rubber. A semiconductor encapsulating material comprising the composition of claim 5, wherein at least one of the resin and the rubber is an epoxy resin.