Epoxy resin composition, electronic component mounting structure, and method for producing electronic component mounting structure

Abstract

The present invention further suppresses the occurrence of recess defects which are formed in a polished surface when a surface of a cured product of an epoxy resin composition is polished. Provided is an epoxy resin composition comprising (A) an epoxy resin, B) at least one component selected from the group consisting of curing agents and curing accelerators, and (C) a filler, wherein the average presence density of recesses which have a diameter of not less than 0.5 μm and which are observed in a polished surface of a cured product of the epoxy resin composition is not more than 1.00 / mm2. Also provided are an electronic component mounting structure using the epoxy resin composition, and a method for producing the electronic component mounting structure.

Description

Epoxy resin composition, electronic component mounting structure, and method for manufacturing electronic component mounting structure

[0001] The present invention relates to an epoxy resin composition, an electronic component mounting structure, and a method for producing an electronic component mounting structure.

[0002] Many semiconductor elements, such as integrated circuits, that constitute semiconductor devices are encapsulated with epoxy resin compositions. Electronic component mounting structures may also be produced through a process in which electronic components other than semiconductor elements are encapsulated with epoxy resin compositions. There are several resin encapsulation (molding) methods for encapsulating electronic components, such as semiconductor elements, including a compression molding method, in which a liquid or granular epoxy resin is supplied to a cavity and then the semiconductor element or other electronic component is immersed in the molten epoxy resin for molding. However, in recent years, the compression molding method, which is suitable for producing large resin-encapsulated products (molded products), has increasingly been adopted. This is due to the increasing popularity of wafer-level chip-size packaging technology. These packaging technologies also include processes known as chip-first and chip-last. In particular, the chip-first process involves first mounting semiconductor elements, such as IC chips, on a wafer, followed by (i) encapsulating the semiconductor elements with an epoxy resin composition, (ii) polishing the surface of the cured epoxy resin composition formed by encapsulation, and (iii) forming a rewiring layer on the polished surface. Therefore, in the chip-first process, it is important to ensure high flatness on the polished surface formed by polishing the surface of the cured epoxy resin composition before forming the rewiring layer.

[0003] On the other hand, as a technique for forming a polished surface having high flatness prior to the formation of a rewiring layer, for example, the technique described in Patent Document 1 is known. In the technique described in Patent Document 1, a polished surface obtained by polishing the surface of a cured product of an epoxy resin composition containing hollow particles with a grinder is polished to a flatness of 25 mm. ２ The number of pores having a diameter of more than 5 μm observed in the range is controlled to one or less.

[0004] International Publication No. 2018 / 225599

[0005] On the other hand, in order to further improve the performance and reliability of electronic component packaging structures manufactured by encapsulating electronic components such as semiconductor elements with a cured product of an epoxy resin composition, it is necessary to form a rewiring layer on a polished surface with even greater flatness than conventional methods. To achieve this, it is important to further suppress the formation of dent defects on the polished surface.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an epoxy resin composition that can further suppress the occurrence of dent defects formed on a polished surface when the surface of a cured product of the epoxy resin composition is polished; an electronic component mounting structure using the same; and a method for manufacturing the electronic component mounting structure.

[0007] The above object is achieved by the present invention as follows: The epoxy resin composition of the present invention is an epoxy resin composition comprising (A) an epoxy resin, (B) at least one component selected from the group consisting of a curing agent and a curing accelerator, and (C) a filler, wherein the average density of dents having a diameter of 0.5 μm or more observed on a polished surface of a cured product of the epoxy resin composition is 1.00 dents / mm ２ The following is the result.

[0008] In one embodiment of the epoxy resin composition of the present invention, it is preferable that the filler (C) does not contain a hollow filler.

[0009] In another embodiment of the epoxy resin composition of the present invention, it is preferable that the (C) filler contains a hollow filler, and that the content of the hollow filler contained in the (C) filler is 100 ppm or less.

[0010] In another embodiment of the epoxy resin composition of the present invention, the viscosity at room temperature is preferably 1 Pa.s or more and 1000 Pa.s or less.

[0011] In another embodiment of the epoxy resin composition of the present invention, the content of the filler component (C) contained in the epoxy resin composition is preferably 55% by mass to 86% by mass.

[0012] Another embodiment of the epoxy resin composition of the present invention is preferably for use in liquid compression molding.

[0013] The electronic component mounting structure of the present invention comprises an electronic component, a cured product of an epoxy resin composition having a polished surface on its surface and sealing the electronic component, and a rewiring layer formed on the polished surface of the cured product, wherein the epoxy resin composition contains (A) an epoxy resin, (B) at least one component selected from the group consisting of a curing agent and a curing accelerator, and (C) a filler, and the average density of depressions of 0.5 μm or more in diameter observed on the polished surface is 1.00 / mm ２ The following is the result.

[0014] The method for producing an electronic component mounting structure of the present invention includes: a sealing step of sealing an electronic component with a cured product of an epoxy resin composition containing (A) an epoxy resin, (B) at least one component selected from the group consisting of a curing agent and a curing accelerator, and (C) a filler; a polished surface forming step of polishing the surface of the cured product to form a polished surface; and a rewiring layer forming step of forming a rewiring layer on the polished surface, wherein the average density of dents with a diameter of 0.5 μm or more observed on the polished surface is 1.00 dents / mm ２ The following is the result.

[0015] In one embodiment of the method for manufacturing an electronic component mounting structure of the present invention, the sealing step is preferably performed by a compression molding method.

[0016] According to the present invention, it is possible to provide an epoxy resin composition that can further suppress the occurrence of dent defects formed on a polished surface when the surface of a cured product of the epoxy resin composition is polished, an electronic component mounting structure using the same, and a method for manufacturing the electronic component mounting structure.

[0017] The epoxy resin composition of the present embodiment includes (A) an epoxy resin, (B) at least one component selected from the group consisting of a curing agent and a curing accelerator, and (C) a filler. The epoxy resin composition has a cured surface having a mean density of pits of 0.5 μm or more in diameter observed on a polished surface of the cured product of the epoxy resin composition of 1.00 / mm. ２Therefore, with the epoxy resin composition of this embodiment, the occurrence of dent defects formed on the polished surface when the surface of a cured product of the epoxy resin composition is polished can be further suppressed. As a result, it becomes easier to further improve the performance and reliability of electronic component packaging structures produced using the epoxy resin composition of this embodiment.

[0018] Herein, the average density of recesses present on a polished surface is measured by the following procedure. First, a cured product obtained by heat-treating an epoxy resin composition at 150°C for 2 hours is used to prepare a polishing sample (length: 1 mm, width: 1 mm, thickness: 500 μm) using a dicing device. Next, the surface of the polishing sample (a surface of length and width: 1 mm x 1 mm) is polished. During polishing, a polishing treatment using a slurry containing an inorganic abrasive with an average particle size of 0.5 μm or less is performed as a final polishing step (final polish) performed immediately before the completion of the polished surface, thereby forming a polished surface to be measured. In this manner, 10 observation samples are prepared.

[0019] Next, the entire polished surface (length: 1 mm, width: 1 mm) of the observation sample was observed using a scanning electron microscope at a magnification of 2000 times, and the number of dents with a diameter of 0.5 μm or more was counted. The same observation was performed on 10 observation samples, and the average number of dents obtained by observation of each observation sample was calculated as the average density of dents with a diameter of 0.5 μm or more (number / mm ２ The average density of dents with a diameter of 0.5 μm or more is set to 0.80 / mm from the viewpoint of suppressing the occurrence of dent defects and further improving the flatness of the polished surface. ２ Preferably, 0.60 pieces / mm or less ２ More preferably, 0.30 pieces / mm or less ２ More preferably, 0.18 pieces / mm or less ２ The number of pieces per mm is particularly preferably 0 pieces per mm or less. ２ is most preferred.

[0020] The average density of dents with a diameter of 0.5 μm or more is 0 / mm ２If the diameter of the pits is more than 1.5 μm, there is a possibility that pits with larger diameters are formed on the polished surface. Even in such a case, in order to ensure the flatness of the polished surface, the average density of pits with a diameter of 1.5 μm to 5.0 μm is set to 0.02 / mm. ２ It is preferable that the number of particles is 0.01 particles / mm or less. ２ It is more preferable that the number of particles is 0 / mm ２ From the same viewpoint, it is more preferable that the average density of recesses having a diameter of more than 5.0 μm is 0 / mm ２ It is preferable that:

[0021] At the time of filing, grinder polishing is the mainstream polishing method used to form a polished surface (final polish) in the manufacture of electronic component packaging structures such as semiconductor devices having rewiring layers (see, for example, JP 2022-141179 A / paragraphs 0020, 0025, etc., JP 2019-129179 A / paragraphs 0054-0055). Therefore, as disclosed in Patent Document 1 (particularly paragraphs 0065-0066, Table 1-2), evaluating dent defects on the polished surface formed by grinder polishing as a final polish is considered useful for improving the performance and reliability of electronic component packaging structures at the time of filing.

[0022] However, grinder polishing, a polishing method in which a grinding wheel is rotated at high speed and brought into contact with the workpiece to grind the surface, is thought to inflict significant mechanical damage on the polished surface during formation, resulting in large numbers and larger dent defects. Furthermore, to further improve the performance and reliability of electronic component mounting structures, it is necessary to form a rewiring layer on a polished surface with even greater flatness than conventional methods. Taking these points into consideration, the inventors of the present invention have determined that it is necessary to address the future predictions shown in (1) to (3) below. (1) It is predicted that in the future, grinder polishing will be replaced by a polishing method that causes less mechanical damage to the polished surface during polishing than grinder polishing, as a final polishing method for forming a polished surface. (2) As a final polishing method that replaces grinder polishing, from the standpoint of cost performance, it is predicted that polishing processes (such as barrel polishing, buffing, and chemical mechanical polishing) using slurries containing inorganic abrasives with an average particle size of 0.5 μm or less (preferably 0.1 μm or less) will become mainstream. (3) The flatness required for a polished surface (in other words, the allowable size of dent defects) is expected to become even stricter in the future than the evaluation criteria set forth in Patent Document 1, which assumes a polished surface formed by grinder polishing (i.e., dent defects of less than 5 μm in diameter are allowable).

[0023] Therefore, in the case of the epoxy resin composition of this embodiment, it was considered extremely important to reduce the size tolerance of dent defects formed on the polished surface of a cured product to less than 0.5 μm, and to evaluate dent defects formed on the polished surface after final polishing using a slurry containing an inorganic abrasive having an average particle size of 0.5 μm or less. Based on the predictions and findings described above, the inventors have discovered the epoxy resin composition, electronic component mounting structure, and method for manufacturing the same of this embodiment.

[0024] Next, the components constituting the epoxy resin composition of the present embodiment will be described in detail below.

[0025] (A) Epoxy Resin The epoxy resin used in the epoxy resin composition of this embodiment is not particularly limited as long as it is any of various epoxy resins generally used for semiconductor encapsulation, but from the viewpoints of viscosity and injectability, it is preferable to use a liquid epoxy resin. Furthermore, the epoxy resin blended in the epoxy resin composition may be a single type of epoxy resin, or two or more types of epoxy resins may be used in combination.

[0026] Specific examples of epoxy resins include, but are not limited to, aromatic epoxy resins and aliphatic epoxy resins. Examples of aromatic epoxy resins include bisphenol A-type epoxy resins such as p-glycidyloxyphenyldimethyltrisbisphenol A diglycidyl ether; bisphenol F-type epoxy resins; novolac-type epoxy resins; fluorene-type epoxy resins; biphenyl aralkyl epoxy resins; diepoxy resins such as p-tert-butylphenyl glycidyl ether and 1,4-phenyldimethanol diglycidyl ether; biphenyl-type epoxy resins such as 3,3',5,5'-tetramethyl-4,4'-diglycidyloxybiphenyl; aminophenol-type epoxy resins such as diglycidylaniline, diglycidyltoluidine, triglycidyl-p-aminophenol, and tetraglycidyl-m-xylylenediamine; naphthalene-type epoxy resins; and epoxy resins having a plant-derived skeleton.

[0027] Specific examples of aliphatic epoxy resins include monofunctional aliphatic epoxy compounds having one epoxy group in the molecule, such as alkyl alcohol glycidyl ethers (butyl glycidyl ether, 2-ethylhexyl glycidyl ether, etc.) and alkenyl alcohol glycidyl ethers (vinyl glycidyl ether, allyl glycidyl ether, etc.); difunctional aliphatic epoxy compounds having two epoxy groups in the molecule, such as polyalkylene glycol diglycidyl ethers (e.g., alkylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether), and alkenylene glycol diglycidyl ether; and polyfunctional aliphatic epoxy compounds having three or more epoxy groups in the molecule, such as polyglycidyl ethers of trifunctional or higher alcohols (e.g., trimethylolpropane triglycidyl ether, pentaerythritol (tri- or tetra-)glycidyl ether, dipentaerythritol (tri-, tetra-, penta-, or hexa-)glycidyl ether, etc.).

[0028] The content of the epoxy resin in the epoxy resin composition is preferably 1 to 50 parts by mass, more preferably 5 to 45 parts by mass, and even more preferably 12 to 40 parts by mass.

[0029] Furthermore, when two or more types of epoxy resin compositions are used in combination, particularly when an aromatic epoxy resin and an aliphatic epoxy resin are used in combination, it is preferable to use a (poly)tetramethylene glycol diglycidyl ether represented by the following general formula (1) as the epoxy resin, from the viewpoint of facilitating the reduction in viscosity of the epoxy resin composition.

[0030]

[0031] In general formula (1), n ​​is preferably a natural number from 1 to 15. The number average molecular weight of the (poly)tetramethylene glycol diglycidyl ether represented by general formula (1) is more preferably 200 to 2000. An example of a commercially available (poly)tetramethylene glycol diglycidyl ether represented by general formula (1) is Epogose PT General Grade.

[0032] Furthermore, in the epoxy resin composition of this embodiment, it is preferable to use a filler (C) having a maximum particle size of 5 μm or less, as described below. When a large amount of a filler having a maximum particle size of 5 μm or less is blended into the epoxy resin composition, the viscosity of the epoxy resin composition is likely to increase, and the preparation of the epoxy resin composition itself may become difficult. However, even in such a case, by using (poly)tetramethylene glycol diglycidyl ether represented by general formula (1) as the epoxy resin, the increase in viscosity of an epoxy resin composition blended with a large amount of a filler having a maximum particle size of 5 μm or less is suppressed, making the preparation of the epoxy resin composition easier and also making it easier to ensure appropriate viscosity and injectability.

[0033] The content of the (poly)tetramethylene glycol diglycidyl ether represented by the general formula (1) is preferably 5.0 parts by mass to 50.0 parts by mass, and more preferably 10.0 parts by mass to 40.0 parts by mass, relative to 100 parts by mass of the total amount of the epoxy resin (A), from the viewpoint of easily ensuring appropriate viscosity and injectability.

[0034] (B) Curing Agent and Curing Accelerator The epoxy resin composition of the present embodiment uses at least one component selected from the group consisting of a curing agent and a curing accelerator. That is, either the curing agent or the curing accelerator may be used alone, or both may be used in combination.

[0035] The curing agent is not particularly limited as long as it is a commonly used curing agent. As the curing agent to be blended into the epoxy resin composition, only one type of curing agent may be used, or two or more types of curing agents may be used in combination. Examples of the curing agent include an amine-based curing agent, an acid anhydride-based curing agent, and a phenol-based curing agent.

[0036] Specific examples of the amine-based curing agent include aliphatic polyamines such as triethylenetetraamine, tetraethylenepentamine, m-xylenediamine, trimethylhexamethylenediamine, and 2-methylpentamethylenediamine; alicyclic polyamines such as isophoronediamine, 1,3-bisaminomethylcyclohexane, bis(4-aminocyclohexyl)methane, norbornenediamine, and 1,2-diaminocyclohexane; piperazine-type polyamines such as N-aminoethylpiperazine and 1,4-bis(2-amino-2-methylpropyl)piperazine; and aromatic polyamines such as diethyltoluenediamine, dimethylthiotoluenediamine, 4,4'-diamino-3,3'-diethyldiphenylmethane, bis(methylthio)toluenediamine, diaminodiphenylmethane, m-phenylenediamine, diaminodiphenylsulfone, diethyltoluenediamine, trimethylenebis(4-aminobenzoate), and polytetramethyleneoxide-di-p-aminobenzoate.

[0037] Specific examples of acid anhydride curing agents include alkylated tetrahydrophthalic anhydrides such as methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhimic anhydride, alkenyl-substituted succinic anhydride, methylnadic anhydride, and glutaric anhydride.

[0038] Specific examples of phenolic curing agents refer to monomers, oligomers, and polymers in general having a phenolic hydroxyl group, such as phenol novolac resins and alkylated or allylated products thereof, cresol novolac resins, phenol aralkyl (including phenylene and biphenylene skeletons) resins, naphthol aralkyl resins, triphenolmethane resins, and dicyclopentadiene-type phenolic resins.

[0039] The amount of curing agent blended into the epoxy resin composition is preferably an amount that results in a stoichiometric equivalent ratio with the epoxy resin (curing agent equivalent / epoxy group equivalent) of 0.01 to 1.5, more preferably 0.02 to 1.4. The blending ratio of the curing agent to the liquid components of the epoxy resin composition excluding the solid components (filler (C) and other solid materials added as needed) is preferably 1 part by mass to 80 parts by mass, more preferably 5 parts by mass to 50 parts by mass.

[0040] The curing accelerator is not particularly limited as long as it is a commonly used curing accelerator. As the curing accelerator blended into the epoxy resin composition, only one type of curing accelerator may be used, or two or more types of curing accelerators may be used in combination. Examples of the curing accelerator include imidazole-based curing accelerators, tertiary amine-based curing accelerators (excluding imidazole-based curing accelerators), and phosphorus-based curing accelerators.

[0041] Specific examples of imidazole-based curing accelerators include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-undecylimidazole, 2-dodecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-benzylimidazole, 2,4,5-trimethylimidazole, and 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine.

[0042] Specific examples of tertiary amine curing accelerators (excluding imidazole curing accelerators) are compounds having one or more tertiary amino groups. Examples of such tertiary amine compounds include methyldiethylamine, dimethylethylamine, triethylamine, tripropylamine, tributylamine, trihexylamine, triethylenediamine (1,4-diazadicyclo(2.2.2)octane (DABCO)), hexamethylenetetramine, N,N,N',N'-tetramethylethylenediamine, N-methylpyrrolidine, N-methylpiperidine, N,N'-dimethylpiperazine, and N-methylmol. Examples of the tertiary amine compounds include aliphatic tertiary amine compounds such as thiazolinone, 1,8-diazabicyclo[5.4.0]undecene-7-ene (DBU), and 1,5-diazabicyclo[4.3.0]-5-nonene (DBN); and aromatic tertiary amine compounds such as N,N-dimethylaniline, N,N-diethylaniline, benzyldimethylamine, triphenylamine, pyridine, 4-dimethylpyridine, 4-hydroxypyridine, 2,2'-dipyridyl, 2,5-dimethylpyrazine, and quinoline.

[0043] Specific examples of phosphorus-based curing accelerators include tertiary phosphines such as triphenylphosphine, and phosphonium salts such as tetraphenylphosphonium and tetraphenylborate.

[0044] The blending ratio of the curing accelerator to the liquid components remaining after excluding the solid components (the (C) filler and other solid materials added as needed) from the epoxy resin composition is preferably 0.01 to 50 parts by mass, more preferably 0.02 to 40 parts by mass, and even more preferably 0.03 to 30 parts by mass.

[0045] (C) Filler The filler is not particularly limited as long as it has the effect of reducing the thermal expansion coefficient of the cured product of the epoxy resin composition. Examples of filler materials include silica, alumina, aluminum, aluminum nitride, silicon carbide, and silicon nitride. As the filler, silica filler is particularly preferred from the viewpoint of being able to increase the amount of filler blended (loading amount) in the epoxy resin composition. In addition, the filler may be surface-treated with a surface treatment agent such as a silane coupling agent.

[0046] The shape of the filler is not particularly limited and may be any of spherical, amorphous, flaky, etc. The average particle size of the filler is preferably 0.01 μm to 10.0 μm, more preferably 0.02 μm to 5.0 μm, and even more preferably 0.03 μm to 2.0 μm. The average particle size refers to the volume average particle size D50 (the particle size at 50% of the cumulative size from the small diameter side of the volume-based particle size distribution) value measured using a laser diffraction particle size distribution measuring device.

[0047] The following two are considered to be the main causes of dent defects that occur when the surface of a cured product of an epoxy resin composition is polished: <1> When dent defects are formed because fillers (especially coarse fillers with a relatively large diameter) present near the surface of the cured product fall off from the surface of the cured product during polishing; <2> When dent defects are formed because the outer shell of fillers with a hollow structure (hereinafter sometimes referred to as "hollow fillers") present near the surface of the cured product is destroyed during polishing, exposing the hollow parts of the hollow fillers to the outside.

[0048] Therefore, in order to suppress the occurrence of dent defects as described in the above items <1> and <2>, it is important to (a) use a filler with a smaller maximum particle size, (b) use a filler that does not contain hollow fillers, or (c) when a filler that contains hollow fillers is used, to use a filler that has a smaller hollow filler content and a maximum particle size that is less likely to cause dents with a diameter of 0.5 μm or more.

[0049] Based on the above findings, the upper limit of the maximum particle size of the filler is preferably 20.0 μm or less, more preferably 12 μm or less, even more preferably 7.5 μm or less, and particularly preferably 5.0 μm or less. When two or more fillers are used in combination, it is preferable that the maximum particle sizes of all fillers be within the above range. On the other hand, the lower limit of the maximum particle size is not particularly limited, but in practice, it is sufficient as long as it exceeds the average particle size. For example, it is preferable that it be 1.1 to 1.4 times the average particle size. Here, the maximum particle size of the filler refers to the volume average particle size D99.95 (the particle size that represents 99.95% of the cumulative particle size from the small diameter end of the volume-based particle size distribution) measured using a laser diffraction particle size distribution analyzer. The filler used in preparing the epoxy resin composition may be one whose average particle size and maximum particle size have been adjusted to the desired values ​​in advance by various classification processes.

[0050] On the other hand, there are various methods for producing fillers. Among these, fillers produced by melting methods, deflagration methods, etc., form particles by entraining air during granulation, resulting in the generation of hollow fillers as unavoidable particles. Typical fillers containing hollow fillers include silica fillers and alumina fillers produced by the above-mentioned production methods. Therefore, from the viewpoint of fundamentally preventing the occurrence of hollow filler-derived dent defects, it is most preferable to use fillers that do not generate hollow fillers during granulation, in other words, fillers that do not contain hollow fillers as unavoidable particles (fillers with a hollow filler content of 0 ppm). Examples of such fillers include fillers produced by wet methods (such as the sol-gel method).

[0051] When the filler used in the epoxy resin composition contains hollow fillers (as unavoidable particles), from the viewpoint of suppressing the occurrence of dent defects, the hollow filler content is preferably 100 ppm or less, more preferably 50 ppm or less, and even more preferably 5 ppm or less, and the smaller the content value, the better. When two or more types of fillers are used in combination, the hollow filler content is preferably 100 ppm or less, based on the total amount of fillers. Furthermore, as the filler containing hollow particles used in the preparation of the epoxy resin composition, a filler in which the content of hollow fillers with large hollow portions has been reduced in advance by precision classification such as destructive classification or wet classification can also be used.

[0052] The content of the filler in the epoxy resin composition is preferably 50% by mass to 95% by mass, more preferably 55% by mass to 86% by mass, and even more preferably 60% by mass to 84% by mass, from the viewpoints of reducing the thermal expansion coefficient of the cured product and facilitating the preparation of an epoxy resin composition having appropriate fluidity.

[0053] (D) Other Components The epoxy resin composition of this embodiment may further contain other components in addition to the above components (A) to (C), as necessary. There are no particular limitations on the other components, but examples include ion trapping agents, leveling agents, antioxidants, antifoaming agents, flame retardants, colorants, reactive diluents, and elastomers. The amounts of the other components to be added can be appropriately selected depending on the types of the other components.

[0054] The epoxy resin composition of this embodiment is prepared by mixing and stirring components (A) to (C) and optional component (D). Known mixing and stirring means, such as a roll mill or planetary mixer, can be used as appropriate for mixing and stirring. When mixing and stirring the components, all components constituting the epoxy resin composition may be mixed and stirred simultaneously. Alternatively, a primary mixture may be prepared by mixing and stirring only some of the components, and the remaining components may then be added to this primary mixture and mixed and stirred. If the filler content used in preparing the epoxy resin composition exceeds 86% by mass, preparation of the epoxy resin composition may become difficult depending on the type and amount of components other than the filler, the mixing and stirring apparatus used for mixing, and the conditions under which the apparatus is used. Therefore, from the perspective of enabling stable and easy preparation of an epoxy resin composition without significant dependence on the type and amount of components other than the filler, the mixing and stirring apparatus used for mixing, and the conditions under which the apparatus is used, the filler content used in preparing the epoxy resin is preferably set to 86% by mass or less, and more preferably set to 84% by mass or less.

[0055] From the viewpoints of handleability and injectability, the viscosity of the epoxy resin composition of the present embodiment at room temperature (25°C) is preferably 1 Pa s to 1000 Pa s, more preferably 5 Pa s to 800 Pa s, and even more preferably 7 Pa s to 700 Pa s.

[0056] The epoxy resin composition of this embodiment can also be suitably used in a process for producing an electromagnetic component mounting structure such as a semiconductor device, which comprises encapsulating an electronic component such as a semiconductor device with a cured product of the epoxy resin composition, polishing the surface of the cured product, and then forming a rewiring layer on the polished surface of the cured product. However, the epoxy resin composition of this embodiment is more suitably used as a compression molding epoxy resin composition for producing an electromagnetic component mounting structure by a compression molding method in the above process.

[0057] The electronic component mounting structure of this embodiment includes an electronic component, a cured product of an epoxy resin composition having a polished surface on its surface and sealing the electronic component, and a rewiring layer formed on the polished surface of the cured product. Here, the epoxy resin composition includes (A) an epoxy resin, (B) at least one component selected from the group consisting of a curing agent and a curing accelerator, and (C) a filler. The average density of dents having a diameter of 0.5 μm or more observed on the polished surface is 1.0 dents / mm ２ The electronic components are typically semiconductor elements, but various electronic elements other than semiconductor elements can also be used. The electronic component mounting structure is typically a semiconductor device.

[0058] The method for producing an electronic component mounting structure of this embodiment includes a sealing step of sealing with a cured product of an epoxy resin composition containing (A) an epoxy resin, (B) at least one component selected from the group consisting of a curing agent and a curing accelerator, and (C) a filler, a polished surface forming step of polishing the surface of the cured product to form a polished surface, and a rewiring layer forming step of forming a rewiring layer on the polished surface, wherein the average density of dents with a diameter of 0.5 μm or more observed on the polished surface is 1.00 dents / mm ２ The sealing step is preferably carried out by a compression molding method.

[0059] In the electronic component mounting structure and the manufacturing method thereof of this embodiment, the average density of dents with a diameter of 0.5 μm or more is set to 0.80 dents / mm from the viewpoint of suppressing the occurrence of dent defects and further improving the flatness of the polished surface. ２ Preferably, 0.60 pieces / mm or less ２ More preferably, 0.30 pieces / mm or less ２ More preferably, 0.18 pieces / mm or less ２ The number of pieces per mm is particularly preferably 0 pieces per mm or less. ２ It is most preferable that the average density of depressions having a diameter of 0.5 μm or more is 0 / mm ２If the diameter of the pits is more than 1.5 μm, there is a possibility that pits with larger diameters are formed on the polished surface. Even in such a case, in order to ensure the flatness of the polished surface, the average density of pits with a diameter of 1.5 μm to 5.0 μm is set to 0.02 / mm. ２ It is preferable that the number of particles is 0.01 particles / mm or less. ２ It is more preferable that the number of particles is 0 / mm ２ From the same viewpoint, it is more preferable that the average density of recesses having a diameter of more than 5.0 μm is 0 / mm ２ It is preferable that:

[0060] Furthermore, in the electronic component mounting structure and its manufacturing method of this embodiment, the polished surface is formed by polishing using a slurry containing an inorganic abrasive with an average particle size of 0.5 μm or less (more preferably 0.1 μm or less) as a final polish. The polishing conditions for forming the polished surface are not particularly limited, except for the above-mentioned conditions for the final polish. For example, the polished surface formation step may involve a multi-step polishing process or only a single-step polishing process (i.e., only the final polishing), but in practice, a multi-step polishing process is preferred. In this case, it is preferable to perform the polishing process in a way that causes less mechanical damage to the polished surface, such as by decreasing the particle size of the abrasive contained in the slurry used as the steps progress.

[0061] Furthermore, when a slurry is used in each step of the polished surface formation process, including the final polish, the material of the inorganic abrasive contained in the slurry can be any known material without particular limitation, such as diamond, alumina, silica, etc. It is preferable to use a slurry containing an inorganic abrasive made of diamond.

[0062] Specific examples of the present invention will be described below with reference to examples, but the present invention is not limited to the examples described below.

[0063] 1. Preparation of Epoxy Resin Compositions The epoxy resin compositions of Examples 1 to 18 and Comparative Example 1 were prepared by mixing and stirring the raw materials using a roll mill so as to obtain the blending ratios shown in Tables 1 and 2. Details of the components (A) to (C) used as raw materials are as follows. The filler used as component (C) was a commercially available filler that was used as is without classification treatment.

[0064] 2. Raw material components used in preparation of epoxy resin compositions (A) Epoxy resins Epoxy resin A (YDF8170, bisphenol F type liquid epoxy resin, manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent 158 ​​g / eq) Epoxy resin B (jER630, aminophenol type liquid epoxy resin, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 98 g / eq) Epoxy resin C (Epogose PT general grade, polytetramethylene glycol diglycidyl ether, manufactured by Yokkaichi Synthetic Co., Ltd., epoxy equivalent 440 g / eq) Epoxy resin D (RE410S, bisphenol A type liquid epoxy resin, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 178 g / eq)

[0065] (B) Curing agents and curing accelerators Curing agent A (HN-2200, acid anhydride curing agent, manufactured by Showa Denko Materials Co., Ltd.) Curing accelerator A (2P4MZ, 2-phenyl-4-methylimidazole, manufactured by Shikoku Chemical Industries Co., Ltd.) Curing accelerator B (2MZA, 2,4-diamino-6-[2'-methylimidazolyl(1')]-ethyl-s-triazine, manufactured by Shikoku Chemical Industries Co., Ltd.)

[0066] (C) Fillers Filler A: Silica filler (average particle size 1.8 μm, maximum particle size 5.0 μm, filler manufacturing method: deflagration method), product name SE605H-SMG, manufactured by Admatechs Co., Ltd. Filler B: Silica filler (average particle size 0.3 μm, maximum particle size 1.0 μm, filler manufacturing method: deflagration method), product name SE101G-SMO, manufactured by Admatechs Co., Ltd. Filler C: Silica filler (average particle size 0.5 μm, maximum particle size 0.7 μm, filler manufacturing method: sol-gel method), product name KE-S50SG, manufactured by Nippon Shokubai Co., Ltd. Filler D: Silica filler (average particle size 0.6 μm, maximum particle size 3.0 μm, filler manufacturing method: deflagration method), product name SE203G-SEJ, manufactured by Admatechs Co., Ltd. Filler E: Silica filler (average particle size 10.0 μm, maximum particle size 20.0 μm, filler manufacturing method: deflagration method), product name STW7010-20, manufactured by Nippon Steel Chemical & Material Co., Ltd. Filler F: Silica filler (average particle size 2.0 μm, maximum particle size 10.0 μm, filler manufacturing method: deflagration method), product name SE6200, manufactured by Admatechs Co., Ltd. Filler G: Silica filler (average particle size 4.0 μm, maximum particle size 10.0 μm, filler manufacturing method: fusion method), product name 40SM-E2, manufactured by Admatechs Co., Ltd. Filler H: Silica filler (average particle size 5.0 μm, maximum particle size 25.0 μm, filler manufacturing method: fusion method), product name FB5SDX, manufactured by Denka Company Limited

[0067] 3. Various evaluation and measurement methods 3.1 Average density of dents (1) Preparation of observation samples Average density of dents (number / mm ２Observation samples used for observing the diced cured product were prepared according to the following procedure. First, the epoxy resin compositions of each Example and Comparative Example were heat-treated at 150°C for 2 hours to obtain cured products. These were then processed using a dicing device to prepare diced cured products (length: 1 mm, width: 1 mm, thickness: 500 μm). Next, the diced cured product was placed with the 1 mm x 1 mm side facing down in the bottom of a Sankei clear cup (outer diameter: 25 mmφ x height: 23 mm, catalog no. 010-0250). A two-component embedding epoxy resin was then poured into the clear cup and left overnight at room temperature to harden the diced cured product around the diced cured product, thereby obtaining a polishing sample. Next, the surface of the polishing sample on the exposed side of the cured product was polished to prepare 10 observation samples. The polishing conditions for polishing the surface of the polishing sample to form a polished surface (the polished surface area of ​​the cured product was 1 mm x 1 mm) were as follows:

[0068] (2) Formation of polished surface and polishing conditions The surface of the polishing sample was subjected to a four-stage polishing process in the order of step 1 to step 4 using a Struers automatic polishing machine (Tegramin-20, manufactured by Struers). The polishing members and polishing times used in each step are as follows. Step 1: Polishing member: Waterproof abrasive paper #600 Polishing time: 3 minutes Step 2: Polishing member: Diamond slurry (manufactured by Engis Japan Co., Ltd., 6-PC, 6μ slurry (particle size range: 4-8μm)) Polishing time: 6 minutes Step 3: Polishing member: Diamond slurry (manufactured by Engis Japan Co., Ltd., 1-PC, 1μ slurry (particle size range: 0-2μm)) Polishing time: 3 minutes Step 4 (final polish): Polishing member: Diamond slurry (manufactured by BUEHLER, Master prep, average particle size 0.05μm) Polishing time: 2 minutes

[0069] The rotation speed and polishing load in steps 1 to 4 are as follows: Rotation speed: 150 rpm Polishing load: 10 N

[0070] (3) Observation of the polished surface The polished surface of the observation sample was observed using a scanning electron microscope (S-3400N, manufactured by Hitachi High-Tech Fielding Corporation) at a magnification of 2000x and an accelerating voltage of 15 kV. The observation range was the entire polished surface (length: 1 mm x width: 1 mm) of the cured product embedded in the observation sample.

[0071] (4) Measurement of the number of dents and calculation of the average density of dents The number of dents with a diameter of 0.5 μm or more was counted on the polished surface of the observation sample (the polished surface of the cured product portion). This was done for 10 observation samples, and the average of the numbers of dents obtained by observation of each observation sample was calculated as the average density of dents with a diameter of 0.5 μm or more (number / mm ２ ) was calculated by the same procedure. ２ ) was also sought.

[0072] 3.2 Average Particle Size and Maximum Particle Size of Filler The average particle size and maximum particle size of the filler used in preparing the epoxy resin compositions of each Example and Comparative Example were measured using a laser diffraction particle size analyzer (LS13320, manufactured by Beckman Coulter, Inc.) according to the following procedure. First, 5 mg of filler was mixed with 50 mg of dispersant (an aqueous solution of 0.5% by mass of Aerosol OT (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in pure water) and dispersed for 10 minutes using an ultrasonic disperser to prepare a measurement sample. Measurements were then performed using this measurement sample under conditions of a flow rate of 50 ml / sec, a measurement time of 90 seconds, pure water as the solvent, and a solvent refractive index of 1.333. A volume-based particle size distribution was obtained. The volume-based particle size distribution was then calculated by determining the volume-based particle size D50 (the particle size corresponding to 50% of the cumulative total from the smallest diameter end of the volume-based particle size distribution) as the average particle size, and the volume-based particle size D99.95 (the particle size corresponding to 99.95% of the cumulative total from the smallest diameter end of the volume-based particle size distribution) as the maximum particle size.

[0073] 3.3 Viscosity of Epoxy Resin Composition The viscosity of the epoxy resin composition of each Example and Comparative Example was measured immediately after preparation of the epoxy resin composition using a Brookfield HB-DV viscometer (model number: HB-DV1) at a liquid temperature of 25°C and a rotation speed of 10 rpm.

[0074] 3.4 Hollow Filler Content in Filler The hollow filler content in the filler was measured using the following procedure. First, 40 g of Solmix AP-1 (an organic solvent, a mixture of ethanol, methanol, and isopropyl alcohol (IPA) manufactured by Japan Alcohol Sales Co., Ltd.) and 10 g of filler were weighed into a sample bottle, and a mixed solution was prepared by stirring the mixture at 2000 rpm for 2 minutes using a stirrer. After stirring, the sample bottle was removed from the stirrer and allowed to stand for 24 hours in an environment at 25°C. After standing, the filler floating on the surface of the mixed solution in the sample bottle was collected together with the mixed solution using a dropper and placed in a container of known weight. The container containing the wet filler was then placed in a dryer set to 150°C and heated to volatilize the solvent (Solmix AP-1) contained in the wet filler, thereby obtaining a dried product (residue). The weight of the container containing the residue was measured, and the weight of the residue was calculated from the difference between the weight of the container and the weight of the residue.The percentage (ppm) of the weight of the residue obtained from 10 g of filler was calculated as the content of hollow filler particles in the filler.

[0075] 4. Evaluation Results Table 1-2 shows the composition of the epoxy resin composition, as well as the average particle size, maximum particle size, and hollow filler content of the filler used, the viscosity of the epoxy resin composition, the average density of depressions with a diameter of 0.5 μm or more, and the average density of depressions with a diameter of 1.5 μm to 5.0 μm. Observation of the polished surfaces with a scanning electron microscope revealed that the majority of depressions with a diameter of 0.5 μm or more observed on the polished surfaces in each Example and Comparative Example were due to hollow fillers. Furthermore, no depressions with a diameter of more than 5.0 μm were observed in any Example.

[0076]

[0077]

Claims

1. (A) an epoxy resin, (B) at least one component selected from the group consisting of a curing agent and a curing accelerator, (C) a filler, An epoxy resin composition containing: The average density of indentations with a diameter of 0.5 μm or more observed on the polished surface of the cured product of the epoxy resin composition is 1.00 pieces / mm ２ or less, epoxy resin composition.

2. The epoxy resin composition according to claim 1, wherein the (C) filler does not contain a hollow filler.

3. The epoxy resin composition according to claim 1, wherein the (C) filler contains a hollow filler, and the content of the hollow filler contained in the (C) filler is 100 ppm or less.

4. The epoxy resin composition according to any one of claims 1 to 3, having a viscosity at room temperature of 1 Pa·s or more and 1000 Pa·s or less.

5. The epoxy resin composition according to any one of claims 1 to 3, wherein the content of the (C) filler component contained in the epoxy resin composition is 55% by mass to 86% by mass.

6. The epoxy resin composition according to any one of claims 1 to 3, which is for liquid compression molding.

7. An electronic component, a cured product of an epoxy resin composition having a polished surface provided on the surface and sealing the electronic component, a rewiring layer formed on the polished surface of the cured product, comprising: The epoxy resin composition is (A) an epoxy resin, (B) at least one component selected from the group consisting of a curing agent and a curing accelerator, and (C) a filler. The average density of depressions with a diameter of 0.5 μm or more observed on the polished surface is 1.00 pieces / mm ２ or less, an electronic component mounting structure.

8. A sealing step of sealing an electronic component with a cured product of an epoxy resin composition containing (A) an epoxy resin, (B) at least one component selected from the group consisting of a curing agent and a curing accelerator, and (C) a filler; a polished surface forming step of forming a polished surface by polishing the surface of the cured product; a rewiring layer forming step of forming a rewiring layer on the polished surface, comprising: The average density of indentations with a diameter of 0.5 μm or more observed on the polished surface is 1.00 pieces / mm ２ The following is a method for manufacturing an electronic component mounting structure.

9. The method for manufacturing an electronic component mounting structure according to claim 8, wherein the sealing step is performed by a compression molding method.