JP2006160560A6 - Spherical sintered ferrite particles, resin composition for semiconductor encapsulation using the same, and semiconductor device obtained using the same - Google Patents

Abstract

The present invention provides a resin composition for encapsulating a semiconductor in which the cured product has an effective electromagnetic wave shielding function and exhibits good moldability.
A resin composition for encapsulating a semiconductor containing spherical sintered ferrite particles having the following characteristics (a) to (c).
(A) The content of soluble ions is 5 ppm or less.
(B) The average particle diameter is in the range of 10 to 50 μm.
(C) The crystal structure by X-ray diffraction shows a spinel structure.
[Selection figure] None

Description

  The present invention relates to spherical sintered ferrite particles excellent in electromagnetic wave shielding properties, and a resin composition for encapsulating a semiconductor, which is a cured body forming material having an electromagnetic wave shielding function and electrical insulation properties using the same, and using the same The present invention relates to the obtained highly reliable semiconductor device.

  Generally, in a semiconductor device manufacturing process, a semiconductor element that has been bonded to a substrate is sealed using a mold resin such as a thermosetting resin in order to avoid contact with the outside. As the mold resin, for example, an inorganic filler mainly composed of silica powder mixed and dispersed in an epoxy resin is used. As a sealing method using this mold resin, for example, a transfer mold method in which a semiconductor element bonded to a substrate is placed in a mold, and the mold resin is pumped into the mold to cure and mold the mold resin is put to practical use. Has been.

  Conventionally, a resin-encapsulated semiconductor device in which a semiconductor element is encapsulated with a mold resin is excellent in terms of reliability, mass productivity, cost, etc., and has been widely used together with a ceramic-encapsulated semiconductor device made of ceramic. Yes.

  By the way, in electrical equipment, the problem of electromagnetic environment compatibility (EMC: Electro-Magnetic-Compatibility) attracts attention. For example, in recent years, information communication equipment has been reduced in size and functionality, and in order to improve the performance of semiconductor elements used in such equipment, the signal amplitude is reduced in order to reduce power consumption. As a result, there is an increased possibility that the semiconductor element will cause a malfunction even with a weak high frequency noise. Therefore, development of an electronic device that does not emit unnecessary electromagnetic waves or has resistance to electromagnetic waves generated in the surroundings is underway.

  Generally, the cured body of the semiconductor sealing resin composition converts this energy into heat when electromagnetic waves are absorbed. The energy conversion efficiency is related to the values of the imaginary part ε ″ of the complex permittivity that is a complex representation of the dielectric constant of the cured body and the imaginary part μ ″ of the complex permeability that is a complex representation of the permeability. These values respectively indicate the magnitude of dielectric loss and magnetic loss of incident electromagnetic wave energy, and the larger each value, the higher the energy conversion efficiency, and hence the higher the electromagnetic wave shielding effect.

  By the way, as one of the solutions to the electromagnetic interference problem, an integrated circuit device including a semiconductor element is built in a package case having a package base and a package cap made of ferrite or a material having characteristics equivalent to this ferrite. It has been proposed to hermetically seal and absorb electromagnetic waves inside and outside the case with the above case (see Patent Document 1).

  A resin seal comprising a semiconductor element bonded on a die pad and a wire connected to the semiconductor element and a lead, and the wire, the semiconductor element, and a part of the lead are sealed with a magnetic resin. A type semiconductor device has been proposed (see Patent Document 2). In this case, the surface of the semiconductor device is covered with a magnetic resin in which ferrite is dispersed to form a two-layer sealing resin structure, or ferrite is used as an alternative to silica particles used as a filler in the sealing resin. Thereby, it can be set as the sealing resin structure of 1 layer.

  Furthermore, there has been proposed a semiconductor package containing a semiconductor element and other elements, wherein the semiconductor package body is made of a plastic resin in which magnetic powder is mixed (see Patent Document 3). In this plastic resin, magnetic powder such as ferrite and amorphous alloy is mixed, and the mixed amount is preferably about 30 to 60% by weight. When the added amount is less than 30% by weight, the electromagnetic noise characteristics are reduced. It is said that improvement cannot be achieved, and even if added in excess of 60% by weight, the effect of increasing the amount is not observed.

The semiconductor device includes a semiconductor component, a wiring metal substrate to which the component is fixed, and a mold resin that directly covers a required portion of the component and the wiring metal substrate. The mold resin is 35 to 95% by weight of the organic resin. A semiconductor device has been proposed in which a thermal expansion coefficient of the mold resin is 14 to 20 ppm / ° C. (see Patent Document 4). To this mold resin, the ferrite powder made of a substance represented by the general formula: MFe ₂ O ₄ or MO · nFe ₂ O ₃ (where M is a divalent metal and n is an integer) is added to an epoxy resin. Yes.

  Moreover, in the resin composition for semiconductor sealing which seals a semiconductor element, the epoxy resin which shows thermosetting, the phenol resin hardening | curing agent which is a hardening | curing agent of the said epoxy resin, and the silica powder which is a filler of the said epoxy resin And a magnetic substance powder, and an average particle diameter of the silica powder is smaller than the average particle diameter of the magnetic substance powder has been proposed (see Patent Document 5). This magnetic powder is characterized by ferrite having an average particle diameter of 10 to 50 μm, a maximum particle diameter of 200 μm or less, and an irregular shape.

Furthermore, in the epoxy resin composition containing (A) an epoxy resin, (B) a curing agent, (C) a magnetic powder, and (D) a curing accelerator as essential components, the (C) magnetic powder is 50 to An epoxy resin composition having a relative magnetic permeability of 3000 and included in the entire epoxy resin composition at 30 to 90% by volume has been proposed (see Patent Document 6). The higher the relative magnetic permeability of this (C) magnetic substance powder is, the lower the value is, and when it is lower than 50, the complex magnetic permeability becomes low when the resin composition is used, and the electromagnetic wave shielding effect is not sufficiently obtained. As the above-mentioned (C) magnetic substance powder, a ferrite-based powder is suitable. In the spinel type, Ni—Zn type ferrite or Mn—Zn type ferrite is used. In the magnetoplumbite type, Zr—Mn type ferrite or It is said that Ti-Mn type ferrite can be suitably used.
JP-A-64-41248 JP-A-3-23654 JP-A-6-151626 Japanese Patent Laid-Open No. 11-40708 JP 2002-363382 A JP 2003-128880 A

  However, the semiconductor package made of ferrite of Patent Document 1 is difficult to process and is not practical in terms of cost. Therefore, there has been a demand for a semiconductor sealing method using ferrite that is easy in manufacturing process and effective and highly reliable as an electromagnetic interference countermeasure.

  Moreover, in the said patent document 2, although the manufacture of the semiconductor device was made easy as a 1 layer resin structure by using a ferrite as a filler of sealing resin, the malfunction by electromagnetic noise was prevented, but a ferrite is contained. Since the resin to be used is in direct contact with the semiconductor element, there is a problem in reliability in the resin composition containing ordinary ferrite with a lot of soluble ions. Further, in Patent Document 3, there is a problem in reliability because a semiconductor element or the like is directly molded with a plastic mixed with a magnetic material.

  And in the said patent document 4, although the reliability is improved by molding with the mold resin of 14-20 ppm / degree C of thermal expansion coefficient which added 35-95 weight% ferrite powder, the moldability and dielectric breakdown of resin are improved. The results of the short circuit test under load or bias voltage load were not disclosed, and there was a problem in the moldability of the mold resin with a high filling rate of ferrite and the reliability when the bias voltage was loaded.

  Furthermore, in the above-mentioned Patent Document 5, as described above, focusing on the risk of causing current malfunction due to the mold resin moldability mixed with ferrite powder and the contact between the semiconductor element and the molded resin cured body, Although a semiconductor sealing resin composition containing a specific silica powder and a ferrite magnetic substance powder has been proposed, the reliability is practically insufficient.

  And in the said patent document 6, although the epoxy resin composition containing the magnetic body powder of the high magnetic permeability of 50-3000 is proposed for semiconductor sealing, the ferrite type powder considered suitable is Even if it has a high magnetic permeability, it is about 30 at most, so it was actually far from satisfying the requirements of the invention. Moreover, the reliability about ferrite was not mentioned, and there was a problem in its use.

  The mold resin that is a resin composition for semiconductor encapsulation needs to have a low viscosity from the requirements of the low-pressure transfer mold to the molding temperature, and high fluidity is required. In such a mold resin system, the pulverized Mn—Zn ferrite and Ni—Zn ferrite obtained by mechanically pulverizing a conventional ferrite ingot can increase the filling rate of ferrite particles for the purpose of increasing the magnetic permeability. could not. In other words, it is necessary to optimize the shape and size of the ferrite particles as a filler for the resin composition for semiconductor encapsulation, and to examine the low ionic impurity content in terms of the reliability of the resin-encapsulated semiconductor device. It had been.

  The present invention has been made in view of such circumstances, and has a spherical sintered ferrite particle useful as a filler for a resin composition for semiconductor encapsulation, and an effective electromagnetic wave shielding function using the same, Another object of the present invention is to provide a semiconductor sealing resin composition exhibiting good moldability and reliability and a semiconductor device sealed using the same.

In order to achieve the above object, the first gist of the present invention is spherical sintered ferrite particles having the following characteristics (a) to (c).
(A) The content of soluble ions is 5 ppm or less.
(B) The average particle diameter is in the range of 10 to 50 μm.
(C) The crystal structure by X-ray diffraction shows a spinel structure.

  Moreover, this invention makes the 2nd summary the resin composition for semiconductor sealing containing the filler which consists of the said spherical sintered ferrite particle and a silica particle.

  Furthermore, this invention makes the 3rd summary the semiconductor device formed by sealing a semiconductor element using the said resin composition for semiconductor sealing.

  That is, the present inventors have made extensive studies focusing on the compounding material of the sealing material in order to obtain a resin composition that is excellent in the electromagnetic wave shielding function and has a good moldability and reliability. Repeated. Focusing on the spinel type ferrite that has been used for providing electromagnetic wave shielding function, a series of researches were conducted to obtain a spinel type ferrite material that combines excellent formability, reliability, and electromagnetic wave shielding properties. Piled up. As a result, soluble ions are 5 ppm or less (a), the average particle diameter is in the range of 10 to 50 μm (b), and the crystal structure by X-ray diffraction shows a spinel structure (c) Spherical sintered ferrite particles are used. And the excellent electromagnetic wave shielding function of the spherical sintered ferrite particles is effectively expressed, and the reliability that is essential for recent sealing materials is ensured, while maintaining a high filling component, It has been found that low viscosity at the time of melting and high strength after curing are possible, and that good moldability can be obtained, and the present invention has been achieved.

  Thus, the present invention is a spherical sintered ferrite particle having the characteristics (a) to (c), and for semiconductor encapsulation containing a filler composed of the special spherical sintered ferrite particle and silica particle. It is a resin composition. For this reason, it has low viscosity and good flow characteristics, and also has an electromagnetic wave shielding function. By using this resin composition as a sealing material, the obtained semiconductor device is excellent in EMC.

  In addition to the above characteristics (a) to (c), the spherical sintered ferrite particles have peaks in the particle size distribution in the range of 5 to 15 μm and the range of 20 to 50 μm [Characteristics] When (d)] is used, its filling property is improved, and it has a higher fluidity and an excellent electromagnetic wave shielding function.

And when the specific surface area by the BET method of the said spherical sintered ferrite particle is 0.02-0.1 m < ² > / g, what was provided with much higher fluidity comes to be obtained.

  Further, when the pore volume of the spherical sintered ferrite particles by the mercury intrusion method is 0.2 liter / kg or less, a product having even higher fluidity can be obtained.

  In the present invention, specific spherical sintered ferrite particles are used, and this specific spherical sintered ferrite particle is most characterized in that it is used for a resin composition for semiconductor encapsulation. For example, an epoxy resin and a phenol resin system are used. It is obtained by using a curing agent, a curing accelerator and silica powder, and is usually in the form of a powder or a tablet obtained by tableting this.

  The above-mentioned specific spherical sintered ferrite particles are washed with water at the raw material stage and further sintered into a spherical shape and then washed with water, or after being sintered into a spherical shape and sufficiently washed with water, The following. Preferably, it is reduced to 1 ppm or less. Thus, it becomes possible to improve the reliability of the resin composition for semiconductor encapsulation by reducing the amount of soluble ions to the limit. If the amount of soluble ions is below the measurement limit, the total amount of detected ions is calculated as 0 ppm.

  The specific spherical sintered ferrite particles are spherical sintered ferrite particles whose crystal structure by X-ray diffraction shows a spinel structure. This is because, in recent years, the operating frequency of semiconductors has exceeded 1 GHz, so that it is possible to cope with higher frequencies of unnecessary radio waves that need to be shielded. The spherical sintered ferrite particles are preferably a metal oxide composed of at least one metal element M and Fe selected from the group consisting of Mg, Zn, Ni, Mn and Cu. That is, the semiconductor sealing material is required to have as high resistance as possible. Further, in the composition of the spherical sintered ferrite particles, the molar ratio of the metal element M and Fe is preferably in the range of M: Fe = 1: 1.57 to 1: 2.17. That is, if the molar ratio of both is out of the above range, ferritization does not proceed sufficiently, and it becomes difficult to secure necessary magnetic properties. In addition, when the sintered ferrite particles have a shape other than a spherical shape, for example, an indeterminate shape, the viscosity of the resin composition is increased and the fluidity is also deteriorated.

The spherical sintered ferrite particles preferably have a specific surface area in the range of 0.02 to 0.1 m ² / g by the BET method. Furthermore, the pore volume by mercury porosimetry is more preferably 0.2 liter / kg or less. Spherical sintered ferrite particles having such a specific surface area and pore area are sintered and the surface properties of the particles are smooth, so that the fluidity of the resin composition at the time of sealing a semiconductor device is improved. . Furthermore, since there are few pores, it becomes easy to wash away soluble ions to 5 ppm or less by washing with water.

  The specific spherical sintered ferrite particles in the present invention must have an average particle size in the range of 10 to 50 μm, more preferably 15 to 40 μm, and substantially no particles exceeding the particle size of 63 μm. Is particularly preferred. Furthermore, in order to improve the filling property of the resin composition for encapsulating a semiconductor of the present invention, to secure fluidity and to maintain 1 GHz μ ″ which is an electromagnetic property high, in the particle size distribution, the particle size 5 It is preferable to have peaks in the range of ˜15 μm and particle sizes in the range of 20 to 50 μm, and it is particularly preferable to use spherical sintered ferrite particles having peaks in the vicinity of 10 μm and 30 μm, respectively. Thus, as a method of obtaining spherical sintered ferrite particles having two peaks in the particle size distribution, for example, spherical sintered ferrite particles having an average particle diameter of 5 to 15 μm and an average particle diameter of 20 to 50 μm. There is a method obtained by mixing and mixing two types of spherical sintered ferrite particles in a range of spherical sintered ferrite particles. This is because spherical sintered ferrite particles having a particle size in the vicinity of m tend to have a high μ ″ of 1 GHz, and have the effect of improving the electromagnetic shielding characteristics of the resin composition for semiconductor encapsulation. In addition, the average particle diameter and particle size distribution of the specific spherical sintered ferrite particles can be measured using, for example, a laser diffraction particle size distribution apparatus.

  Such specific spherical sintered ferrite particles can be produced, for example, as follows. First, the case where ferrite raw material powder is used will be described. That is, each raw material weighed in a desired composition is stirred and mixed in an aqueous solvent and adjusted to a water-dispersed slurry having a slurry concentration of 60 to 90% by weight, and then the slurry is spray-dried, and then at about 800 to 1300 ° C. Spherical sintered ferrite particles are generated by heat treatment. The obtained spherical sintered ferrite particles are stirred and washed for 30 minutes in pure water having an electric conductivity of 1 μS / cm or less with a volume ratio of about 30 times, and then dried to produce specific spherical sintered ferrite particles. Can do.

  As the ferrite raw material powder serving as the component element supply source of the specific spherical sintered ferrite particles in the present invention, Mg, Zn, Ni, Mn, Cu oxide, hydroxide, oxalate, carbonate, etc. may be used. it can. Further, iron oxide is used as the Fe element supply source, and the mixture is used so as to achieve the desired ferrite composition ratio.

  The ferrite raw material powder may have any particle form such as cubic, polyhedral, needle-like, or plate-like. The average particle diameter of the ferrite raw material powder is preferably 0.01 to 5.0 μm, more preferably 0.1 to 2.0 μm. That is, if it is less than 0.01 μm, the slurry viscosity becomes high, and there is a tendency to cause trouble when spray drying. If it exceeds 5.0 μm, the surface roughness of the sintered body increases and the specific surface area becomes too large. This is because the filling rate tends to not increase.

  An agglomeration inhibitor may be used when slurrying in the production process of the specific spherical sintered ferrite particles. As the anti-aggregation agent, a general surfactant can be used, and those having a functional group capable of binding to a hydroxyl group when it is present on the surface of inorganic compound particles or sintered ferrite particles are preferable. Examples thereof include carboxylic acid sodium salt, anionic polycarboxylic acid ammonium salt, and naphthalenesulfonic acid sodium salt. In view of the residue of ionic impurities after firing, it is preferable to use a 40% solution of ammonium polycarboxylate anion.

  In other production methods, the ferrite raw material powder is weighed to a desired composition and stirred and mixed by dry mixing or wet mixing, followed by primary sintering at 800 to 900 ° C., dry pulverization or wet pulverization. .1 to 5.0 μm ferrite crystal particles are prepared. Next, the slurry containing the ferrite crystal particles is adjusted to an aqueous dispersion slurry having a slurry concentration of 60 to 90% by weight, the slurry is spray-dried, and then heat treated at 900 to 1300 ° C. Generate particles. The obtained spherical sintered ferrite particles are stirred and washed for 30 minutes in pure water having an electric conductivity of 1 μS / cm or less with a dilution volume ratio of about 30 times, and then dried to produce the spherical sintered ferrite particles of the present invention. can do. In addition, as a coagulation inhibitor used when making the said slurry, the thing similar to what is used in the case of manufacture using the ferrite raw material powder mentioned previously is used.

  The ferrite crystal particles may be particles in any form such as a cubic shape, a polyhedral shape, a needle shape, and a plate shape. The average particle diameter of the ferrite crystal particles is preferably 0.01 to 5.0 μm, more preferably 0.2 to 3.0 μm. That is, if it is less than 0.01 μm, the slurry viscosity becomes high, and there is a tendency to cause trouble when spray drying. If it exceeds 5.0 μm, the surface roughness of the sintered body increases and the specific surface area becomes too large. This is because the filling rate tends to not increase.

  In the production of the spherical sintered ferrite particles in the present invention, the spray drying is preferably performed at a slurry concentration of 50 to 90% by weight, more preferably 50 to 80% by weight. That is, when the amount is less than 50% by weight, the pore volume tends to increase. When the amount exceeds 90% by weight, the slurry viscosity increases, it is difficult to ensure a spherical shape, and the particle size distribution is difficult to adjust. This is because there is a tendency to become.

  Furthermore, in this invention, although it changes with compositions of a ferrite, it bakes for 1 to 8 hours at the temperature of about 800-1300 degreeC. That is, when the temperature is lower than 800 ° C., the tendency to become ferritic tends to be insufficient, and when the temperature exceeds 1300 ° C., the sintered particles tend to be fused with each other, and the snowball-shaped shaped particles tend to increase.

  In order to improve the electromagnetic wave shielding effect, the blend ratio of such specific spherical sintered ferrite particles in the resin composition for semiconductor encapsulation is such that the imaginary part μ ″ of the complex magnetic permeability of the resin composition cured body is large. Therefore, the blending ratio of the spherical sintered ferrite particles is preferably set to 32.5% by volume or more, more preferably 40% by volume or more of the total resin composition, and the upper limit is generally 80. The upper limit is generally a range in which the fluidity of the resin composition is ensured, and if this upper limit is exceeded, the fluidity tends to decrease and processing tends to be difficult.

  The semiconductor sealing resin composition of the present invention has the greatest feature of using the specific spherical sintered ferrite particles as described above, and includes, for example, an epoxy resin and a phenol resin. It is obtained by using a system curing agent, and further a curing accelerator and silica powder.

  The epoxy resin is not particularly limited as long as it is solid at room temperature (25 ° C.), and conventionally known ones such as biphenyl type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, and the like. can give. These may be used alone or in combination of two or more.

  The phenolic resin-based curing agent functions as a curing agent for the epoxy resin, and is not particularly limited as long as it exhibits a solid at room temperature (25 ° C.). Examples thereof include novolak, cresol novolak, bisphenol A type novolak, naphthol novolak, and phenol aralkyl resin. These may be used alone or in combination of two or more.

  As for the blending ratio of the epoxy resin and the phenol resin-based curing agent, the hydroxyl group equivalent in the phenol resin is preferably set in the range of 0.5 to 1.6 with respect to 1 equivalent of the epoxy group in the epoxy resin. More preferably, it is set in the range of 0.8 to 1.2.

  The curing accelerator is not particularly limited and is conventionally known, for example, 1,8-diazabicyclo (5,4,0) undecene-7, tertiary amines such as triethylenediamine, 2-methylimidazole, etc. And phosphorus-based curing accelerators such as imidazoles, triphenylphosphine, and tetraphenylphosphonium tetraphenylborate. These may be used alone or in combination of two or more.

  Content of the said hardening accelerator is normally set to the range of 0.5-10 parts with respect to 100 weight part (henceforth "part") of the said phenol resin type hardening | curing agent.

  In the semiconductor sealing resin composition of the present invention, together with the spherical sintered ferrite particles as a filler, silica particles conventionally used as a semiconductor sealing material in order to reduce molding burrs are used in combination. The combined ratio of the spherical sintered ferrite particles and the silica particles is not particularly limited, but in order to increase the electromagnetic shielding effect, the larger the spherical sintered ferrite particles, the more preferable. The ratio of the spherical sintered ferrite particles is preferably 50% by volume or more of the entire filler (spherical sintered ferrite particles and silica particles). Furthermore, it is preferable to set the total volume of the spherical sintered ferrite particles and the silica particles to a range of 65 to 80% by volume of the entire resin composition. That is, when the total volume is less than 65% by volume, the linear expansion coefficient of the resin composition for semiconductor encapsulation becomes large, and cracks may occur due to a temperature cycle or the like due to a difference from the linear expansion coefficient of the semiconductor element. Moreover, when it exceeds 80 volume%, the fluidity | liquidity of the resin composition for semiconductor sealing will fall, it will become difficult to seal a semiconductor element, and the deformation | transformation or cutting | disconnection of the gold wire which couple | bonds a semiconductor element and an electrode will be carried out. This is because there is a risk that the above may occur.

  As the silica particles, those having an average particle size of 1 to 40 μm and a maximum particle size of 200 μm or less, more preferably a maximum particle size of 100 μm or less, particularly preferably 63 μm or less are used. More preferably, silica particles having an average particle diameter of 5 to 15 μm and silica particles having an average particle diameter of 0.2 to 2 μm are used in combination. And fluidity can be improved. Specifically, silica particles having an average particle diameter of 5 to 15 μm are added to 4 to 30% by volume of the whole filler, spherical sintered ferrite particles having an average particle diameter of 20 to 50 μm are added to 50 to 93% by volume of the whole filler, and average particles It is preferable to set the silica particles having a diameter of 0.2 to 2 μm to 3 to 30% by volume of the whole filler. Alternatively, by replacing part or all of the silica particles having an average particle diameter of 5 to 15 μm with spherical sintered ferrite particles, that is, by using spherical sintered ferrite particles having an average particle diameter of 5 to 15 μm, the electromagnetic wave shielding characteristics are further improved. It becomes possible. In addition, the average particle diameter of the said silica particle can be measured using a laser diffraction type particle size distribution apparatus similarly to the case of the above-mentioned specific spherical sintered ferrite particle.

  Examples of the silica particles include spherical fused silica powder, ground silica powder, and crushed silica powder. In particular, it is preferable to use spherical fused silica powder because the effect of reducing the melt viscosity of the resin composition for semiconductor encapsulation is increased.

  In addition, according to the use of a semiconductor device, use environment, etc., you may further mix | blend various fillers with the resin composition for semiconductor sealing of this invention. As such a filler, for example, calcium carbonate powder, titanium white, alumina powder, silicon nitride powder and the like can be used, and these can be used alone or in combination of two or more.

  Furthermore, you may mix | blend other additives, such as a stress reducing agent, a pigment, a mold release agent, a coupling agent, and a flame retardant, with a semiconductor sealing resin composition as needed.

  Examples of the stress reducing agent include silicone compounds such as side chain ethylene glycol type dimethylsiloxane, acrylonitrile-butadiene rubber, and the like.

  Examples of the pigment include carbon black and titanium oxide.

  Examples of the release agent include polyethylene wax, carnauba wax, fatty acid salt and the like.

  Examples of the coupling agent include silane coupling agents such as γ-glycidoxypropyltrimethoxysilane and β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane.

  Moreover, brominated epoxy resin etc. can be used as said flame retardant, Flame retardant adjuvants, such as antimony trioxide, etc. are used for this.

  In addition to the flame retardant, a metal hydroxide represented by the following general formula (1) can be used. This metal hydroxide has a polyhedral shape in crystal form, not a conventional hexagonal plate shape, or a so-called thin plate-like crystal shape such as a scale shape. The crystal growth in the thickness direction (c-axis direction) as well as length and width is large. For example, a plate-like crystal grows in the thickness direction (c-axis direction) and is more like a three-dimensional and spherical shape. It refers to a metal hydroxide having a crystal shape, such as a substantially dodecahedron, a substantially octahedron, or a substantially tetrahedron.

  Such a metal hydroxide having a polyhedral shape has a crystal growth in the thickness direction (c-axis direction) as well as in the vertical and horizontal directions, for example, by controlling various conditions in the production process of the metal hydroxide. A metal hydroxide having a large desired polyhedral shape, for example, a substantially dodecahedron, a substantially octahedron, a substantially tetrahedron, or the like can be obtained, and is usually composed of a mixture thereof.

As specific representative examples of the metal hydroxide having the polyhedral shape, Mg _1-X Ni _X (OH) ₂ [0.01 <X <0.5], Mg _1-X Zn _X (OH) ₂ [0.01 <X <0.5] and the like. Examples of commercial products of these metal hydroxides include Echo Mug manufactured by Tateho Chemical Industry Co., Ltd.

  Moreover, the aspect-ratio of the metal hydroxide which has the said polyhedral shape is 1-8 normally, Preferably it is 1-7, Most preferably, it is 1-4. The aspect ratio here is represented by the ratio between the major axis and the minor axis of the metal hydroxide. That is, when the aspect ratio exceeds 8, there is a tendency that the melt viscosity of the epoxy resin composition containing the metal hydroxide is increased.

  The resin composition for semiconductor encapsulation according to the present invention can be produced, for example, as follows. In other words, epoxy resin, phenol resin-based curing agent, curing accelerator, spherical sintered ferrite particles, and if necessary, inorganic fillers such as silica particles, low stress agents, pigments, mold release agents, coupling agents and difficult A predetermined amount of other additives such as a flame retardant is blended. Next, using a hot roll, an extruder, a kneader or the like, for example, the mixture is sufficiently melt-kneaded and dispersed in a temperature environment of 95 to 100 ° C., for example. And this mixture is cooled and grind | pulverized, The powdery resin composition for semiconductor sealing which passed the 10-mesh sieve can be manufactured. Moreover, the resin composition for semiconductor sealing of the target form can be manufactured according to a series of processes of compression-molding into a tablet shape as needed.

  The resin composition for encapsulating a semiconductor thus obtained mainly encapsulates the semiconductor element of the semiconductor device in detail, protects the semiconductor element from physical contact with the outside, and shields electromagnetic waves. Used for applications.

  A semiconductor device encapsulated with the resin composition for encapsulating a semiconductor of the present invention will be described with reference to a cross-sectional view thereof.

  A semiconductor device 10 shown in FIG. 1 is an area mounting type semiconductor device, and a wiring 11 is embedded in a through hole in a substrate 11. An electrode 15 connected to the wiring 12 is formed on the substrate 11 and a semiconductor element 14 is mounted thereon. On the other hand, a solder ball 13 is provided on the other surface side of the substrate 11 and is electrically connected to the electrode 15 via the wiring 12, and the semiconductor element 14 is electrically connected to the electrode 15 via the wire bonding 17. In FIG. 1, reference numeral 16 denotes a cured body formed by the semiconductor resin composition of the present invention that seals the semiconductor element 14.

  FIG. 2 is a cross-sectional view of another example of a semiconductor device sealed with a resin composition for a semiconductor of the present invention. The semiconductor device 20 is a peripheral terminal mounting type semiconductor device, and a semiconductor element 22 mounted on a substrate 21 is connected to an electrode 23 via a wire bonding 25. The entire semiconductor element 22 is resin-sealed with a cured body 24 over both surfaces of the substrate 21.

  The semiconductor devices 10 and 20 having the configuration shown in FIGS. 1 and 2 include, for example, a semiconductor composition for semiconductor encapsulation that is heated after the semiconductor elements 14 and 22 mounted on the substrates 11 and 21 are placed in a molding die. It can be manufactured using a low-pressure transfer molding method or the like in which an object is transferred and molded at a low pressure.

  As an example, first, the semiconductor elements 14 and 22 disposed on the substrates 11 and 21 and connected to the electrodes 15 and 23 via the wire bondings 17 and 25, respectively, are formed from an upper mold and a lower mold. Set to type. Next, the semiconductor sealing resin composition is pressurized and transferred with a plunger, and the pressure is maintained until it is cured. After the curing, the upper mold and the lower mold are removed, and the semiconductor devices 10 and 20 in which the semiconductor elements 14 and 22 are sealed with the cured bodies 16 and 24 are manufactured.

  In the semiconductor devices 10 and 20 thus obtained, the semiconductor elements 14 and 22 are protected from the outside, and electromagnetic waves are generated by the magnetic loss of the specific sintered ferrite powder contained in the cured bodies 16 and 24. Since it is shielded, it can be applied to electronic devices or electronic devices that require EMC.

  Next, examples will be described together with comparative examples.

First, spherical sintered ferrite was prepared as shown below.
[Preparation of Spherical Sintered Ferrite a]
The ferrite raw material powder is NiO 15 mol%, ZnO 25 mol%, CuO 12 mol% and Fe ₂ O ₃ 48 mol%. The total amount of 4 kg is charged into a ball mill together with 2.6 kg of pure water for 20 minutes. Stir. Subsequently, 20 g of polycarboxylic acid ammonium salt anion 40% (manufactured by San Nopco, SN Dispersant 5468) is added as an aggregation inhibitor, and 10 g of silicone antifoaming agent (manufactured by San Nopco, SN deformer 465) is added and mixed. Thus, a slurry was prepared. The resulting slurry concentration was 60% by weight. Subsequently, the slurry was spray-dried to obtain a granulated powder. The obtained powder was a powder in which raw material particles were gathered in a spherical shape, and the surface had unevenness on the surface as it was in the size and distribution of the raw material. Next, the powder was heat-treated at 800 ° C. for 2 hours, and then heat-treated (fired) at 1000 ° C. for 3 hours to obtain spherical sintered ferrite particles having a smooth surface. Subsequently, spherical sintered ferrite particles a having a soluble ion content of 5 ppm or less were prepared by stirring, washing, dewatering and drying for 20 minutes in ion-exchanged water having a total weight of 30 times twice. The crystal structure by X-ray diffraction was a spinel structure.

[Preparation of Spherical Sintered Ferrite b]
NiO and 15 mol% is a ferrite material powder, ZnO and 25 mol%, 12 mol% of CuO, Fe ₂ O ₃ so that the proportion of 48 mol% and wet-mixed, heat treatment for 2 hours at 800 ° C. at dehydration after conventional methods ( Calcination was performed, and the obtained ferrite powder was pulverized by a dry method to obtain ferrite crystal particles having an average particle diameter of 1 μm. Subsequently, 4 kg of the ferrite crystal particles were collected and charged into 1.3 kg of pure water. Next, 30 g of polycarboxylic acid ammonium salt anion 40% (manufactured by San Nopco, SN Dispersant 5468) is added as an aggregation inhibitor, and 16 g of silicone antifoaming agent (manufactured by San Nopco, SN deformer 465) is added and mixed. -A slurry was prepared by stirring. The resulting slurry concentration was 75% by weight. Subsequently, the slurry was spray-dried to obtain a granulated powder. The obtained powder was a powder in which ferrite crystal particles having an average particle size of 1 μm were gathered into a spherical shape, and the particle size distribution on the surface was uneven as it was. Subsequently, spherical sintered ferrite particles having a smooth surface were obtained by heat treatment (firing) at 1000 ° C. for 3 hours. Then, spherical sintered ferrite particles b having a soluble ion of 5 ppm or less were prepared by stirring, washing, dewatering and drying for 20 minutes in ion-exchanged water having a total weight of 30 times twice. The crystal structure by X-ray diffraction was a spinel structure.

[Production of Spherical Sintered Ferrite Particles ck]
The average particle diameter, composition, slurry concentration, and washing water dilution factor of the raw material powder or ferrite crystal particles were changed as shown in Table 1 below. Otherwise, spherical sintered ferrite particles c to k were prepared in the same manner as the spherical sintered ferrite particles a or b. In addition, all the crystal structures by X-ray diffraction were spinel structures.

  However, the spherical sintered ferrite particles h were not washed with water. In addition, in the spherical sintered ferrite particles e, g, j and k, not only the slurry concentration was changed, but also the average particle size was controlled by classification operation.

  And while manufacturing conditions in connection with preparation of spherical sintered ferrite particle ak are shown in Table 1 of a postscript, the physical property of obtained spherical sintered ferrite particle ak is measured according to the method shown below, and the result is shown. It is shown in Table 2 below. The production method (a) described in Table 1 below indicates that the production method was the same as that for the spherical sintered ferrite particles a, and the production method (b) is the production method for the spherical sintered ferrite particles. It shows that it produced with the production method similar to b. Moreover, the average particle diameter in the preparation method (a) represents the particle diameter of the raw material powder, and the average particle diameter in the preparation method (b) represents the average particle diameter of the ferrite crystal particles.

[Observation of particle morphology]
The particle morphology was observed using a scanning electron microscope (S-800, manufactured by Hitachi, Ltd.).

[Measurement of average particle size and particle size distribution]
The average particle size and particle size distribution were measured by a dry method using a laser diffraction particle size distribution device (manufactured by SYMPATEC, HELOS & RODOS). The particle diameter is based on volume, and the average particle diameter is 50%. The dispersion air pressure was set to 300 Pa, the dispersion time was 1.5 to 4 seconds, and the transmittance was 2 to 50%.

(Measurement of pore volume)
The pore volume was measured with a mercury intrusion autopore 922 (manufactured by Shimadzu Corporation).

[Measurement of BET specific surface area]
The BET specific surface area was measured by a nitrogen adsorption method using a fully automatic surface area measuring device 4 soap manufactured by Yuasa Ionics.

[Measurement of soluble ion content]
Using a pressure vessel made of Teflon (registered trademark), 5 g of pure water was added to 5 g of the test sample, and after sealing, extracted at 121 ° C. for 20 hours and cooled, the extract was subjected to ion chromatography (made by Nippon Dionex, DX- 500 and DX-AQ) were used to measure ionic species and their amounts.

[Examples 1-8, Comparative Examples 1-6]
Biphenyl type epoxy resin (softening point 105 ° C., epoxy equivalent 192), phenol aralkyl resin (softening point 60 ° C., hydroxyl group equivalent 169), brominated bisphenol A type epoxy resin (softening point 77 ° C., epoxy equivalent 465) as a flame retardant, Antimony trioxide, tetraphenylphosphonium tetraphenylborate, carbon black, γ-glycidoxypropyltrimethoxysilane as a silane coupling agent, polyethylene wax and spherical silica powder α (spherical fused silica, average particle size 8.0 μm, maximum The particle diameter is 9.0 μm), spherical silica powder β (spherical fused silica, average particle diameter of 1.5 μm, maximum particle diameter of 1.9 μm) and the spherical sintered ferrites a to k are used. They were blended and mixed at the ratio shown in Table 4. In Examples 4, 5, 7, and 8, two kinds of spherical sintered ferrite particles having different average particle diameters were mixed in advance and used. The particle size distribution of the mixed spherical sintered ferrite particles of Example 5 is shown in FIG. In FIG. 3, it can be seen that there are peaks near 10 μm and 30 μm. Similarly, the particle size distribution of Examples 4, 7, and 8 was measured. As a result, in Example 4, the particle size distribution had peaks in the vicinity of 10 μm and 30 μm. In Example 7, the particle size distribution had peaks in the vicinity of 12 μm and in the vicinity of 40 μm. Furthermore, in Example 8, the particle size distribution had peaks in the vicinity of 12 μm and in the vicinity of 30 μm.

  Next, the mixture was melt-mixed for 3 minutes with a hot roll heated to a temperature of 95 to 110 ° C. and cooled, and then a powdery semiconductor sealing resin composition that passed through a 10-mesh sieve was prepared.

[Preparation of test piece]
A molded body for measuring magnetic properties and dielectric properties was produced as follows. That is, the powdered resin composition for encapsulating a semiconductor was tablet-molded into a tablet having a diameter of 35 mm under the conditions of molding pressure 6.86 MPa × mold temperature 175 ° C. × molding time 2 minutes, and further at a temperature of 175 ° C. A molded body was produced by curing under conditions of 5 hours. Next, this molded body was cut into a cylindrical donut-shaped test piece having an outer diameter of 7 mm, an inner diameter of 3 mm, and a thickness of 2 mm using an ultrasonic cutter.

[Measurement of magnetic and dielectric properties]
The magnetic properties and dielectric properties were measured by mounting the above-mentioned donut-shaped test piece on a network analyzer 8720D manufactured by Hewlett-Packard Co., and measuring under the coaxial tube method and 1 GHz conditions.

(Measurement of melt viscosity)
The melt viscosity at 175 ° C. of the obtained powdery resin composition for encapsulating a semiconductor was measured using a Koka type flow tester (manufactured by Shimadzu Corporation, CFT500 type).

[Measurement of molding burr]
Using a resin burr evaluation mold (5 to 20 μm clearance), the length of the resin burr leaked from the cavity was measured using a caliper.

[Accelerated reliability test]
A semiconductor device was produced by transfer molding (conditions: 175 ° C. × 2 minutes, 175 ° C. × 5 hours post-curing) using the powdery resin composition for encapsulating a semiconductor. This semiconductor device (package) is a 16-pin dual in-line package (DIP), and the semiconductor element has an aluminum wiring formed on Si via an insulating film. A pressure cooker bias test (PCBT) was performed on each of the 10 semiconductor devices of the example and the comparative example thus manufactured. For this PCBT, a bias voltage of 5 V was applied in a high-temperature and high-humidity bath of 130 ° C. × 85% RH, and the time for disconnecting the aluminum wiring was measured. And, when the time when 50% of the semiconductor elements were disconnected exceeded 100 hours, ○, when 50% of the semiconductor elements were disconnected within 100 hours, x, and further 50% of the semiconductor elements were disconnected within 40 hours Things were evaluated as xx.

  The results thus measured are also shown in Tables 5 to 6 below.

  From the results shown in Tables 5 to 6, the resin composition for semiconductor encapsulation, which is an example product in which spherical sintered ferrite particles having a spinel structure having a soluble ion of 5 ppm or less and an average particle diameter of 10 to 50 μm, are blended. It can be seen that the complex permeability is large and the electromagnetic wave shielding function is excellent. Moreover, all melt viscosity has an appropriate viscosity of 300-400 dPa * s, and is excellent in fluidity | liquidity. Moreover, molding burrs are small, and favorable results were obtained in the accelerated reliability test. Further, in the particle size distribution, for semiconductor sealing, which is a product of Examples 4 and 5 in which spherical sintered ferrite particles having a spinel structure each having a peak in the range of 5 to 15 μm and in the range of 20 to 50 μm are mixed. The resin composition had a particularly high complex permeability and an excellent electromagnetic wave shielding function. Moreover, in Examples 7 and 8, a resin composition having a low melt viscosity was obtained for the high complex permeability.

  On the other hand, the comparative product in which the spherical sintered ferrite particles deviating from the characteristics of the spherical sintered ferrite particles used in the present invention are inferior in the reliability test, or the melt viscosity is too high and the continuous production is performed. Or the melt viscosity is too low and the molding burr is large, and the required magnetic loss μ ″ cannot be ensured.

It is sectional drawing which shows an example of the semiconductor device of this invention. It is sectional drawing which shows the other example of the semiconductor device of this invention. 6 is a curve diagram showing a particle size distribution of spherical sintered ferrite particles used in Example 5. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,20 Semiconductor device 11,21 Substrate 14,22 Semiconductor element 16,24 Hardened body

Claims (15)

Spherical sintered ferrite particles having the following characteristics (a) to (c):
(A) The content of soluble ions is 5 ppm or less.
(B) The average particle diameter is in the range of 10 to 50 μm.
(C) The crystal structure by X-ray diffraction shows a spinel structure. 2. Spherical sintered ferrite particles according to claim 1, wherein in addition to the characteristics (a) to (c), the following characteristic (d) is provided.
(D) The particle size distribution of the spherical sintered ferrite particles has a peak in the range of 5 to 15 μm and the range of 20 to 50 μm.   The spherical sintered ferrite according to claim 1 or 2, wherein the spherical sintered ferrite particles are an oxide composed of Fe and at least one metal element M selected from the group consisting of Mg, Zn, Ni, Mn and Cu. particle.   4. The spherical shape according to claim 3, wherein a molar ratio (M: Fe) between the metal element M and Fe constituting the spherical sintered ferrite particle is in a range of M: Fe = 1: 1.57 to 1: 2.17. Sintered ferrite particles. The spherical sintered ferrite particles according to claim 1, wherein the spherical sintered ferrite particles have a specific surface area of 0.02 to 0.1 m ² / g according to the BET method.   The spherical sintered ferrite particles according to any one of claims 1 to 5, wherein the spherical sintered ferrite particles have a pore volume of 0.2 liter / kg or less by a mercury intrusion method.   A resin composition for encapsulating a semiconductor, comprising a filler composed of the spherical sintered ferrite particles according to claim 1 and silica particles.   The resin composition for semiconductor encapsulation according to claim 7, wherein the content ratio of the filler composed of the spherical sintered ferrite particles and the silica particles is in the range of 65 to 80% by volume of the whole resin composition.   The resin composition for encapsulating a semiconductor according to claim 7 or 8, wherein in the filler composed of the spherical sintered ferrite particles and the silica particles, the proportion of the spherical sintered ferrite particles is 50% by volume or more of the entire filler. The resin composition for semiconductor encapsulation according to claim 9, wherein the composition of the filler composed of the spherical sintered ferrite particles and the silica particles is set to the following (d1) to (d3).
(D1) Silica particles having an average particle diameter of 5 to 15 μm are 4 to 30% by volume of the whole filler.
(D2) Spherical sintered ferrite particles having an average particle diameter of 20 to 50 μm are 50 to 93% by volume of the whole filler.
(D3) Silica particles having an average particle diameter of 0.2 to 2 μm are 3 to 30% by volume of the whole filler. The resin composition for semiconductor encapsulation according to claim 9, wherein the composition of the filler composed of the spherical sintered ferrite particles and the silica particles is set to the following (d4) to (d6).
(D4) Spherical sintered ferrite particles having an average particle diameter of 5 to 15 μm are 4 to 30% by volume of the whole filler.
(D5) Spherical sintered ferrite particles having an average particle diameter of 20 to 50 μm are 50 to 93% by volume of the whole filler.
(D6) Silica particles having an average particle diameter of 0.2 to 2 μm are 3 to 30% by volume of the whole filler.   The resin composition for semiconductor encapsulation according to any one of claims 7 to 11, wherein the silica particles are spherical silica particles.   The resin composition for semiconductor encapsulation according to any one of claims 7 to 12, wherein the resin composition for semiconductor encapsulation contains an epoxy resin and a phenol resin-based curing agent.   The resin composition for semiconductor encapsulation according to claim 13, wherein the resin composition for semiconductor encapsulation contains a curing accelerator together with an epoxy resin and a phenol resin curing agent.   The semiconductor device formed by sealing a semiconductor element using the resin composition for semiconductor sealing as described in any one of Claims 7-14.

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