JP2018016761A - Epoxy resin composition for sealing, cured product, and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To be applicable for producing an encapsulating material for a semiconductor device, to give high reliability of moisture resistance to the semiconductor device, and to have a good releasability at the time of producing the encapsulating material, and high continuous moldability. There is provided an epoxy resin composition for encapsulation which can have: An epoxy resin composition for encapsulation comprises a phosphonium salt (A) represented by the following formula (1), an epoxy resin (B), a curing agent (C), and an inorganic filler (D). And a release agent (E). The release agent (E) contains a copolymer (E1) of α-olefin and maleic anhydride. [Selection diagram] None

Description

  The present invention relates to a sealing epoxy resin composition, a cured product of the sealing epoxy resin composition, and a semiconductor device including a sealing material made from the sealing epoxy resin composition.

  Conventionally, in order to protect semiconductor elements such as transistors, ICs, LSIs and the like from the external environment and improve the handling characteristics of the semiconductor elements, the semiconductor elements are packaged in a plastic package, for example, sealed with an epoxy resin composition. A semiconductor device has been obtained.

  Generally, a curing accelerator is blended in the epoxy resin composition in order to accelerate the curing reaction during molding. Examples of the curing accelerator include amines, imidazole compounds, nitrogen-containing heterocyclic compounds such as 1,8-diazabicyclo (5,4,0) undecene-7, phosphine compounds, quaternary ammonium compounds, quaternary compounds. A phosphonium compound, an arsonium compound, etc. are mentioned.

  In order to obtain a semiconductor device having excellent moisture resistance reliability, Patent Documents 1 and 2 propose a phenol resin salt of alkyl quaternized phosphonium derived from triphenylphosphonium as a curing accelerator in an epoxy resin composition for sealing. Has been.

JP 2004-256663 A JP 2005-162944 A

  However, when the epoxy resin composition contains a phosphonium salt as a curing accelerator, the moisture resistance reliability of the sealing material produced from the epoxy resin composition can be improved, but the separation when removing from the mold is possible. Since the moldability is inferior, there is a problem that the productivity of the semiconductor device is lowered.

  Therefore, the present inventors tried to secure releasability and improve continuous moldability by blending a release agent with the epoxy resin composition. In that case, the sealing material and the lead frame were used. It has been found that there is a problem that it is difficult to ensure adhesion to a substrate such as the above, and the moisture resistance reliability of the semiconductor device is likely to be deteriorated.

  The present invention has been made in view of the above reasons, and can be applied to produce a sealing material for a semiconductor device, can impart high moisture resistance reliability to the semiconductor device, and is good when producing a sealing material. The epoxy resin composition for sealing which has a good mold release property and can have high continuous moldability, the cured product of the epoxy resin composition for sealing, and the epoxy resin composition for sealing An object is to provide a semiconductor device including a sealing material.

  An epoxy resin composition for sealing according to one embodiment of the present invention includes a phosphonium salt (A) represented by the following formula (1), an epoxy resin (B), a curing agent (C), and an inorganic filler (D ) And a release agent (E).

In Formula (1), R ^{1 to} R ³ are each independently an aryl group having 6 to 12 carbon atoms, R ⁴ is an alkyl group having 1 to 4 carbon atoms, and R ⁶ and R ⁸ are each Independently COOH, or OH, R ⁵ and R ⁷ are each independently H or an alkyl group having 1 to 4 carbon atoms, each of R ⁹ and R ¹¹ is H, and R ¹⁰ is COOH, Or, OH, and p, q, and r are numbers satisfying the relations of p ≧ 1, q ≧ 1, r ≧ 1, and q ≧ r.

  The release agent (E) contains a copolymer (E1) of an α-olefin and maleic anhydride.

  The hardened | cured material which concerns on 1 aspect of this invention is obtained by hardening the said epoxy resin composition for sealing.

  A semiconductor device according to one embodiment of the present invention includes a semiconductor element and a sealing material that seals the semiconductor element, and the sealing material is the cured product.

  According to the present invention, it can be applied to produce a sealing material for a semiconductor device, can impart high moisture resistance reliability to the semiconductor device, has good releasability when producing the sealing material, and is high. A semiconductor device provided with an epoxy resin composition for sealing that can have continuous moldability, a cured product of the epoxy resin composition for sealing, and a sealing material made from the epoxy resin composition for sealing is obtained. It is done.

  Hereinafter, an embodiment of the present invention will be described.

  The epoxy resin composition for sealing according to this embodiment includes a phosphonium salt (A), an epoxy resin (B), a curing agent (C), an inorganic filler (D), and a release agent (E). Containing.

  The phosphonium salt (A) is represented by the following formula (1).

In the formula (1), R ^{1 to} R ³ are each independently an aryl group having 6 to 12 carbon atoms. R ⁴ is an alkyl group having 1 to 4 carbon atoms. R ⁶ and R ⁸ are each independently COOH or OH. R ⁵ and R ⁷ are each independently H or an alkyl group having 1 to 4 carbon atoms. Each of R ⁹ and R ¹¹ is H. R ¹⁰ is COOH or OH.

  In Formula (1), p, q, and r are positive numbers. The relations p ≧ 1, q ≧ 1, r ≧ 1, and q ≧ r are satisfied.

  The release agent (E) contains a copolymer (E1) of an α-olefin and maleic anhydride.

  Since the sealing epoxy resin composition contains the phosphonium salt (A), a semiconductor device including a sealing material made of a cured product of the sealing epoxy resin composition has high moisture resistance reliability. Furthermore, since the sealing epoxy resin composition contains the copolymer (E1), the sealing epoxy resin composition has high releasability at the time of molding, and good adhesion between the cured product and the metal. It is hard to lose the nature. Therefore, the epoxy resin composition for sealing can have high continuous moldability without impairing the moisture resistance reliability of the semiconductor device including the sealing material made of the cured product.

  Each component of the epoxy resin composition for sealing according to an embodiment of the present invention will be described in detail.

  First, the phosphonium salt (A) will be specifically described.

  As described above, the phosphonium salt (A) is represented by the following formula (1).

In the formula (1), R ^{1 to} R ³ are each independently an aryl group having 6 to 12 carbon atoms. R ⁴ is an alkyl group having 1 to 4 carbon atoms. R ⁶ and R ⁸ are each independently COOH or OH. R ⁵ and R ⁷ are each independently H or an alkyl group having 1 to 4 carbon atoms. Each of R ⁹ and R ¹¹ is H. R ¹⁰ is COOH or OH.

  In Formula (1), p, q, and r are positive numbers. The relations p ≧ 1, q ≧ 1, r ≧ 1, and q ≧ r are satisfied. In this case, the curing property of the epoxy resin composition for sealing is particularly high, and the phosphonium salt (A) is particularly easily dispersed and melted in the epoxy resin composition for sealing. For this reason, the adhesiveness at the time of shaping | molding of the epoxy resin composition for sealing can be improved. Furthermore, a semiconductor device including a sealing material made of a cured product of the sealing epoxy resin composition is excellent in moisture resistance reliability. In particular, it is preferable that p / q is 1 and q / r is in the range of 1-9.

  The phosphonium salt (A) includes a quaternary phosphonium cation (A1) represented by the following formula (1.1), an organic carboxylate anion (A2) represented by the following formula (1.2), and the following formula (1.3). And a phenol compound (A3) shown in FIG.

  In the phosphonium salt (A), the quaternary phosphonium cation (A1) represented by the formula (1.1) and the organic carboxylate anion (A2) represented by the formula (1.2) are ionically bonded. Furthermore, the organic carboxylate anion (A2) represented by the formula (1.2) and the phenol compound (A3) represented by the formula (1.3) are hydrogen-bonded. Therefore, the phosphonium salt (A) is a complex. It is a compound of the shape. An example of a conceptual model of the structure of this phosphonium salt (A) is shown in the following formula (2).

  When the phosphonium salt (A) is used, an epoxy resin composition for sealing excellent in fluidity, curability and storage stability can be obtained. This is considered to be caused by the following interaction between the three elements of the quaternary phosphonium cation (A1), the organic carboxylate anion (A2) and the phenol compound (A3) constituting the phosphonium salt (A). It is done.

  As shown in the formula (2), each of the organic carboxylate anion (A2) and the phenol compound (A3) has a hydroxyl group or a carbonyl group which is a hydrogen bondable substituent at the 1,3-position. The interaction by hydrogen bond works strongly between the anion (A2) and the phenol compound (A3). Thereby, the acid strength of the organic carboxylate anion (A2) is apparently strong, and the organic carboxylate anion (A2) and the phosphonium salt (A3) are hardly dissociated. For this reason, the quaternary phosphonium cation (A1) and the organic carboxylate anion (A2) in the phosphonium salt (A) are not dissociated at room temperature, so that the epoxy resin composition for sealing is cured. Is suppressed. For this reason, the epoxy resin composition for sealing is considered to have excellent storage stability. Even when the epoxy resin composition for sealing is heated, the strong interaction between the organic carboxylate anion (A2) and the phenol compound (A3) is initially maintained, so that the quaternary phosphonium cation (A1). And organic carboxylate anion (A2) are inhibited from dissociating. For this reason, even if the epoxy resin composition for sealing is heated, the curing reaction does not proceed immediately, and an increase in the melt viscosity of the epoxy resin composition for sealing is suppressed. Thereby, it is thought that the epoxy resin composition for sealing has excellent fluidity at the time of molding. After a while from the start of heating, the interaction between the organic carboxylate anion (A2) and the phenol compound (A3) gradually weakens, and the quaternary phosphonium cation (A1) and the organic carboxylate anion (A2) Dissociate. Thereby, hardening of the epoxy resin composition for sealing is accelerated | stimulated. For this reason, it is thought that high fluidity and curability are compatible.

In the present embodiment, in Formula (1), R ^{1 to} R ³ are each independently an aryl group having 6 to 12 carbon atoms, and R ⁴ is an alkyl group having 1 to ⁴ carbon atoms, whereby a phosphonium salt ( There are few steric hindrances of the quaternary phosphonium cation (A1) and the organic carboxylate anion (A2) in A), so that the stability of the phosphonium salt (A) is high. In addition, since R ⁶ and R ⁸ are each independently COOH or OH, and R ¹⁰ is COOH or OH, interaction between the organic carboxylate anion (A2) and the phenol compound (A3) Works strongly and has excellent storage stability of the sealing epoxy resin composition as described above, excellent fluidity during molding, and excellent curability, and a semiconductor device comprising a sealing material made of the cured product Provides excellent moisture resistance reliability. In addition, since R ⁵ and R ⁷ are each independently H or an alkyl group having 1 to 4 carbon atoms, the functional groups that react with the epoxy resin on the aromatic ring are not adjacent to each other, and the functional group that reacts with the epoxy resin. Steric hindrance around the group is suppressed. For this reason, when the epoxy resin composition for sealing is cured, the probability that functional groups that react with the epoxy resin remain unreacted is reduced, and high cured product characteristics are imparted to the epoxy resin composition for sealing. By these, since the epoxy resin composition for sealing is excellent in fluidity | liquidity and a dispersibility, it can also contribute to the improvement of continuous moldability by being excellent in the moldability at the time of shaping | molding.

In the formula (1), at least one of R ⁶ and R ⁸ is preferably a carboxyl group. In this case, the storage stability of the sealing epoxy resin composition, the fluidity and curability during molding are further improved, and the adhesion between the sealing material containing the cured product and the lead frame is further improved. The reason is presumed as follows. Since the carboxyl group and the carboxylate anion are lower in nucleophilicity than the hydroxyl group, when at least one of R ⁶ and R ⁸ is a carboxyl group, the phosphonium salt (A) reacts with the epoxy resin (B). Initially, no rapid reaction occurs. Even if the reaction proceeds, the carboxylate anion reacts first, and the carboxyl group tends to remain without reacting. Therefore, the storage stability of the epoxy resin composition for sealing and the fluidity during molding are good. When the reaction proceeds to some extent, the phenolic compound (A3) is dissociated from the organic carboxylate anion (A2), and high nucleophilic reactivity of the hydroxyl group in the phenolic compound (A3) is expressed. Curing of the object is promoted. Thereby, the epoxy resin composition for sealing has high curability. The carboxyl group in the organic carboxylate anion (A2) tends to remain in the cured product even after the epoxy resin composition for sealing is cured. For this reason, when the cured product comes into contact with the metal surface, the carboxyl group in the composition (X) is likely to bond with the metal element to form a carboxylate, and when a hydroxyl group or an oxide film is present on the metal surface, the carboxyl group The group tends to hydrogen bond with the metal surface. For this reason, hardened | cured material can have high adhesiveness between metal surfaces, and, thereby, a sealing material can have high adhesiveness between lead frames.

In the formula (1), it is also preferable that R ¹⁰ is a hydroxyl group. In this case, the epoxy resin composition for sealing can have higher storage stability, higher fluidity during molding, and higher curability. This is presumably because in the phosphonium salt (A), the interaction due to hydrogen bonding between the organic carboxylate anion (A2) and the phenol compound (A3) is more likely to occur. In particular, a high effect can be obtained when at least one of R ⁶ and R ⁸ is a carboxyl group and R ¹⁰ is a hydroxyl group. This is because the phenol compound (A3) is different from the organic carboxylate anion (A2) in the phosphonium salt (A), and the carboxylate anion group in the organic carboxylate anion (A2) It is thought that this is because the interaction due to hydrogen bonding is more likely to occur because the two hydroxyl groups are easily arranged close to each other.

  Further, the phosphonium salt (A) does not contain benzene, and benzene is not generated during the synthesis of the phosphonium salt (A) and is not mixed into the phosphonium salt (A). For this reason, discharge | release of the benzene derived from the hardening accelerator from the epoxy resin composition for sealing is suppressed.

  Moreover, when preparing the sealing epoxy resin composition by heating and kneading the raw materials, the phosphonium salt (A) is easily dispersed and melted in the sealing epoxy resin composition. For this reason, when sealing a semiconductor element with the epoxy resin composition for sealing, it is suppressed that the particle | grains of a phosphonium salt (A) are caught between wires or between bumps, and cause insulation failure.

  Even if the melting point or softening point of the phosphonium salt (A) is a relatively high temperature of 200 ° C. or higher, the phosphonium salt (A) is easily dispersed and melted in the sealing epoxy resin composition. This is considered to be because the dispersibility of the phosphonium salt (A) in the sealing epoxy resin composition is enhanced by some intermolecular interaction.

  In order for the phosphonium salt (A) to be particularly easily dispersed and melted in the epoxy resin composition for sealing, the melting point or softening point of the phosphonium salt (A) is preferably 200 ° C. or less, and preferably 70 to 140 ° C. If it is in the range, it is more preferable. When the melting point or softening point is 140 ° C. or lower, the phosphonium salt (A) is particularly easily dispersed and melted in the sealing epoxy resin composition. Further, when the melting point or softening point is 70 ° C. or higher, fusion when the phosphonium salt (A) is pulverized into powder is particularly suppressed, and the powdered phosphonium salt (A) is stored during storage. It becomes difficult to block. The melting point or softening point is more preferably within the range of 80 to 120 ° C, and particularly preferably within the range of 90 to 100 ° C.

  In order to obtain the melting point or softening point of the phosphonium salt (A), the DSC curve is obtained by performing differential scanning calorimetry of the phosphonium salt (A) under the air atmosphere at a temperature rising rate of 20 ° C./min. obtain. The temperature at which the endothermic peak in the DSC curve appears is defined as the melting point or softening point.

  As a method for lowering the melting point or softening point of the phosphonium salt (A), a master batch of the phosphonium salt (A) with a phenol resin can be mentioned. The phenol resin preferably has a low viscosity. Examples of the phenol resin include bisphenol A, bisphenol F, phenol novolac resin, cresol novolac resin, and phenol aralkyl resin. A known method can be used for masterbatching.

  It is also preferred that the phosphonium salt (A) is in powder form. Also in this case, the phosphonium salt (A) is particularly easily dispersed and melted in the sealing epoxy resin composition. As a method of making the phosphonium salt (A) into a powder form, pulverization of the phosphonium salt (A) with an impact pulverizer or the like can be mentioned. The powdered phosphonium salt (A) preferably has a 100 mesh pass of 95% or more. It is preferable that 95% by mass or more of the powdered phosphonium salt (A) pass through 100 mesh (aperture 212 μm). This 100 mesh pass is measured by the air jet sieve method. In this case, the phosphonium salt (A) is very easily dispersed and melted in the sealing epoxy resin composition.

  The method for synthesizing the phosphonium salt (A) is not particularly limited. For example, first, an intermediate composed of a quaternary phosphonium cation represented by the formula (1.1) and an organic carboxylate anion represented by the formula (1.2) is synthesized. A phosphonium salt (A) is obtained by mixing with the phenol compound shown.

  An intermediate can be manufactured by the method currently disclosed by patent 4429768, for example. For example, a salt exchange reaction between an alkyl carbonate of a quaternary phosphonium corresponding to a quaternary phosphonium cation represented by formula (1.1) and an organic carboxylic acid corresponding to an organic carboxylate anion represented by formula (1.2) The intermediate is then synthesized.

  A quaternary phosphonium alkyl carbonate can be obtained, for example, by reacting a tertiary phosphine corresponding to the quaternary phosphonium with a carbonic diester. Examples of the tertiary phosphine include triphenylphosphine, tris (4-methylphenyl) phosphine, and 2- (diphenylphosphino) biphenyl. Examples of the carbonic acid diester include diethyl carbonate, dimethyl carbonate, dibutyl carbonate, and diphenyl carbonate. In order to complete the reaction quickly and with good yield, it is preferable to carry out the reaction in a solvent. Examples of the solvent include methanol and ethanol. In order to synthesize a quaternary phosphonium alkyl carbonate, for example, a tertiary phosphine and a carbonic acid diester are added to a solvent to prepare a reaction solution, and this reaction solution is placed in an autoclave within a range of 50 to 150 ° C. For 10 to 200 hours.

  The intermediate comprises a quaternary phosphonium hydroxide corresponding to the quaternary phosphonium cation represented by formula (1.1) and an organic carboxylic acid corresponding to the organic carboxylate anion represented by formula (1.2). It may be synthesized by a salt exchange reaction.

  The quaternary phosphonium hydroxide can be obtained, for example, by reacting a tertiary phosphine corresponding to the quaternary phosphonium with an alkyl halide or an aryl halide, followed by salt exchange with an inorganic alkali. As the tertiary phosphine, the same thing as the case of obtaining the alkyl carbonate of quaternary phosphonium can be mentioned. Examples of the alkyl halide include ethyl bromide, butyl chloride, 2-ethylhexyl bromide, 2-butyl ethanol, and 2-chloropropanol. Examples of the halogenated aryl include bromobenzene, bromonaphthalene, and bromobiphenyl. Examples of the inorganic alkali include sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide and aluminum hydroxide. In order to complete the reaction quickly and with good yield, it is preferable to carry out the reaction in a solvent. Examples of the solvent include methanol and ethanol. In order to synthesize a quaternary phosphonium hydroxide, for example, a tertiary phosphine and an alkyl halide or aryl halide and an inorganic alkali are added to a solvent to prepare a reaction solution. The reaction solution is then added to an autoclave. The reaction is carried out at a temperature in the range of 20 to 150 ° C. for 1 to 20 hours.

  When a quaternary phosphonium alkyl carbonate or hydroxide and an organic carboxylic acid are reacted, for example, a solution containing a quaternary phosphonium alkyl carbonate or hydroxide and an organic carboxylic acid is used, for example, 30 to 170. While reacting at a temperature in the range of 1 ° C. for 1 to 20 hours, by-produced alcohol, water, carbon dioxide gas and a solvent are removed as required. Thereby, an intermediate body is obtained by salt exchange reaction.

  The intermediate is particularly preferably synthesized by a salt exchange reaction between a quaternary phosphonium alkyl carbonate and an organic carboxylic acid. In this case, mixing of ionic impurities such as halogen ions into the final product phosphonium salt (A) is suppressed. For this reason, generation | occurrence | production of the migration in the sealing material produced from the epoxy resin composition for sealing containing a phosphonium salt (A) is suppressed, For this reason, a semiconductor device provided with a sealing material has high reliability.

As described above, the phosphonium salt (A) is obtained by mixing the intermediate and the phenol compound. For this purpose, for example, the intermediate and the phenol compound are mixed in a solvent such as methanol and ethanol at 50 to 200 ° C. for 1 to 20 hours, and then the solvent is removed. In order to remove the solvent, for example, the solution is heated at 50 to 200 ° C. under reduced pressure or normal pressure. Thereby, a phosphonium salt (A) is obtained.

  The halogen ion content that is an impurity in the phosphonium salt (A) is preferably 5 ppm or less with respect to the phosphonium salt (A). In this case, migration in the sealing material produced from the epoxy resin composition for sealing is particularly suppressed, and thus a semiconductor device including the sealing material has particularly high reliability. Such a low halogen ion content can be achieved by synthesizing the phosphonium salt (A) by a method including a salt exchange reaction between a quaternary phosphonium alkyl carbonate and an organic carboxylic acid, as described above. .

  It is preferable that a phosphonium salt (A) exists in the range of 1-20 mass parts with respect to 100 mass parts of epoxy resins (B). When the phosphonium salt (A) is 1 part by mass or more, particularly excellent curability is imparted to the sealing epoxy resin composition. Moreover, if the phosphonium salt (A) is 20 parts by mass or less, particularly excellent fluidity during molding is imparted to the epoxy resin composition for sealing. It is particularly preferable if the phosphonium salt (A) is in the range of 2 to 15 parts by mass.

  In the range which does not deviate from the objective of this invention, the epoxy resin composition for sealing may contain hardening accelerators other than phosphonium salt (A) in addition to phosphonium salt (A). For example, the epoxy resin composition for sealing includes triarylphosphines, tetraphenylphosphonium / tetraphenylborate, imidazoles such as 2-methylimidazole, and 1,8-diazabicyclo as curing accelerators other than the phosphonium salt (A). One or more components selected from the group consisting of (5, 4, 0) undecene-7 can be contained. It is preferable that the curing accelerator other than the phosphonium salt (A) is 50% by mass or less with respect to the entire curing accelerator including the phosphonium salt (A).

  The release agent (E) will be specifically described.

  The release agent (E) contains a copolymer (E1) of an α-olefin and maleic anhydride. For this reason, the epoxy resin composition for sealing has high releasability. Furthermore, a semiconductor device provided with a sealing material made of a cured product of an epoxy resin composition for sealing is excellent in moisture resistance reliability, and the epoxy resin composition for sealing does not hinder adhesion during molding, High continuous moldability.

  Moreover, since the copolymer (E1) has a polar group derived from maleic anhydride, this epoxy resin composition for sealing has excellent dispersibility and solvent solubility, and is derived from α-olefin. Since the hydrophobic functional group to be used has affinity for the hydrophobic component, this sealing epoxy resin composition is excellent in fluidity and solubility during molding. For this reason, since the moldability at the time of shaping | molding of the epoxy resin composition for sealing can improve, it can contribute to mold release property and continuous moldability.

  Particularly in this embodiment, since the epoxy resin composition for sealing contains a phosphonium salt (A) and further contains a copolymer (E1), the epoxy resin composition for sealing has excellent continuous moldability. Can have. That is, the excellent continuous moldability of the sealing epoxy resin composition can be realized by a synergistic action of the phosphonium salt (A) and the copolymer (E1).

  The copolymer (E1) preferably has a repeating unit represented by the following formula (5).

In the formula (5), R ¹² is preferably an alkyl group having 26 or more carbon atoms. R ¹² is specifically an alkyl group having 26 to 58 carbon atoms, for example.

  The content of the release agent (E) with respect to the total amount of the epoxy resin composition for sealing is preferably in the range of 0.01 to 0.5% by mass, and in the range of 0.05 to 0.5% by mass. If it is in the range of 0.1-0.3 mass%, it is still more preferable.

  The content of the copolymer (E1) with respect to the total amount of the epoxy resin composition for sealing is preferably in the range of 0.01 to 0.5% by mass. If it exists in this range, the fluidity | liquidity at the time of shaping | molding of the epoxy resin composition for sealing and mold release property can be made compatible. The content of the copolymer (E1) is more preferably in the range of 0.05 to 0.3% by mass, and still more preferably in the range of 0.1 to 0.3% by mass.

  The weight average molecular weight of the copolymer (E1) is, for example, in the range of 5000 to 15000.

  The release agent (E) may contain components other than the copolymer (E1) within a range not departing from the object of the present invention. Examples of components other than the copolymer (E1) are, for example, higher fatty acids, higher fatty acid esters, higher fatty acid calcium, and the like, and specific examples include carnauba wax and polyethylene-based wax.

  The epoxy resin (B) will be described. The epoxy resin (B) is a compound having two or more epoxy groups in one molecule. The epoxy resin (B) includes, for example, one or more components selected from the group consisting of bisphenol A type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, and triphenylmethane type epoxy resin. Can be contained. In particular, the epoxy resin (B) contains at least one of a biphenyl type epoxy resin and a low moisture absorption type epoxy resin having a phenyl ring to which a lower alkyl group is added, which improves the reliability of the semiconductor device. Therefore, it is preferable. It is preferable that the epoxy equivalent of an epoxy resin (B) exists in the range of 150-290. The softening point or melting point of the epoxy resin (B) is preferably in the range of 50 to 130 ° C.

  It is preferable that an epoxy resin (B) exists in the range of 0.9-1.5 equivalent with respect to 1 equivalent of hardening | curing agents (C). In this case, the sealing material made of the cured product can have particularly high adhesion even at high temperatures, and the epoxy resin composition for sealing can have good storage stability. For this reason, a semiconductor device provided with the sealing material produced from the epoxy resin composition for sealing can provide still higher moisture resistance reliability. More preferably, the epoxy resin (B) is in the range of 1.0 to 1.3 equivalents.

  The curing agent (C) will be described. The curing agent (C) acts as a curing agent for the epoxy resin (B). The curing agent (C) preferably contains one or more components selected from the group consisting of a phenol compound, an acid anhydride, and a functional compound that generates a phenolic hydroxyl group. In particular, when the curing agent (C) contains at least one of a phenol compound and a functional compound, very high moisture resistance reliability is imparted to a semiconductor device including a sealing material made from an epoxy resin composition for sealing. Is done.

The phenol compound may include all monomers, oligomers and polymers having two or more phenolic hydroxyl groups in one molecule. For example, the curing agent (C) is one or more components selected from the group consisting of phenol novolak resins, cresol novolak resins, biphenyl type novolak resins, triphenylmethane type resins, naphthol novolak resins, phenol aralkyl resins, and biphenyl aralkyl resins. Can be contained. In particular, the curing agent (C) preferably contains at least one of a low hygroscopic phenol aralkyl resin and a biphenyl aralkyl resin in order to improve the reliability of the semiconductor device. Curing agent (C
) Is a phenol compound, the hydroxyl equivalent of the phenol compound per equivalent of epoxy group of the epoxy resin (B) is preferably within the range of 0.5 to 2.0, and 0.8 to 1.4. If it is in the range, it is more preferable.

  Acid anhydrides include, for example, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, benzophenone tetracarboxylic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyltetrahydroanhydride One or more components selected from the group consisting of phthalic acid and polyazeline acid anhydride can be contained. When the curing agent (C) is an acid anhydride, the acid anhydride per equivalent of epoxy group of the epoxy resin (B) is preferably within a range of 0.7 to 1.5 equivalents, 0.8 to More preferably within the range of 1.2 equivalents.

  As a functional compound which produces | generates a phenolic hydroxyl group, the compound which produces | generates a phenolic hydroxyl group by heating is mentioned. More specifically, examples of the functional compound include benzoxazines that open a ring to generate a phenolic hydroxyl group when heated.

  The inorganic filler (D) will be described. The inorganic filler (D) can contain a material that is generally blended with the epoxy resin composition without any particular limitation. For example, the inorganic filler (D) is fused silica, spherical silica, spherical fused silica, crushed silica, crystalline silica, spherical alumina, magnesium oxide, boron nitride, aluminum nitride, etc .; high dielectric constant filler such as barium titanate, titanium oxide, etc. Magnetic fillers such as hard ferrite; inorganic flame retardants such as magnesium hydroxide, aluminum hydroxide, antimony trioxide, antimony pentoxide, guanidine salts, zinc borate, molybdenum compounds, zinc stannate; and talc, barium sulfate One or more components selected from the group consisting of calcium carbonate, mica powder and the like can be contained. In particular, the inorganic filler (D) preferably contains spherical fused silica. The average particle diameter of the inorganic filler (D) is preferably in the range of 3 to 40 μm. In this case, the fluidity of the epoxy resin composition for sealing at the time of molding is particularly good. The average particle size is measured with a laser diffraction / scattering particle size distribution analyzer.

  It is preferable that an inorganic filler (D) exists in the range of 70-95 mass% with respect to the whole epoxy resin composition for sealing. When the inorganic filler (D) is 95% by mass or less, the fluidity during molding of the sealing epoxy resin composition is particularly excellent, and defects such as wire flow and unfilling are suppressed. When the inorganic filler (D) is 70% by mass or more, the melt viscosity at the time of molding of the sealing epoxy resin composition is suppressed from being excessively increased, thereby forming the sealing epoxy resin composition. Appearance defects due to voids or the like in the sealing material to be performed are suppressed. It is particularly preferable if the inorganic filler (D) is in the range of 85 to 92% by mass with respect to the entire sealing epoxy resin composition.

  In addition to the above components (A) to (E), the sealing epoxy resin composition is a pigment such as a silane coupling agent, a flame retardant, a flame retardant aid, an ion trap agent, carbon black, a colorant, a low stress You may contain additives, such as an agent, a tackifier, and a silicone flexible agent.

  The silane coupling agent preferably has two or more alkoxy groups. Examples of the silane coupling agent include β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-mercaptopropyltrimethoxy. One or more components selected from the group consisting of silane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-anilinopropyltrimethoxysilane, and hexamethyldisilazane. Can be contained.

The flame retardant can contain a novolac-type brominated epoxy resin, a metal hydroxide and the like. In particular, the flame retardant preferably contains at least one of diantimony trioxide and diantimony pentoxide.

  The ion trapping agent can contain a known compound having an ion trapping ability. For example, the ion trapping agent can contain hydrotalcites, bismuth hydroxide and the like.

  Examples of the stress reducing agent include butadiene rubbers such as methyl acrylate-butadiene-styrene copolymer and methyl methacrylate-butadiene-styrene copolymer, and silicone compounds.

  The manufacturing method of the epoxy resin composition for sealing is demonstrated. After mixing the phosphonium salt (A), the epoxy resin (B), the curing agent (C), the inorganic filler (D), the release agent (E), and additives as necessary, such as a heat roll and a kneader A powdery epoxy resin composition for sealing can be obtained by melting and mixing in a heated state using a kneader, subsequently cooling to room temperature, and further pulverizing by a known means. You may obtain the tablet-form sealing epoxy resin composition which has a size and mass corresponding to molding conditions by tableting this powdery sealing epoxy resin composition.

  A cured product obtained by thermally curing the epoxy resin composition for sealing is suitable as a sealing material for sealing a semiconductor element in a semiconductor device. A semiconductor device provided with such a sealing material will be described.

  The semiconductor device includes a semiconductor element such as an IC chip and a sealing material that seals the semiconductor element. The sealing material is a cured product of the epoxy resin composition for sealing. The semiconductor device may further include a base material that supports the semiconductor element. The base material is, for example, a lead frame or a wiring board. The sealing material can be produced by a known molding method such as a transfer molding method, a compression molding method, or an injection molding method.

  When manufacturing a semiconductor device, for example, a semiconductor is first mounted on a base material. The semiconductor element is electrically connected to the base material by a method such as flip chip bonding or wire bonding. The base material on which the semiconductor element is mounted is set in a transfer mold. In this state, the epoxy resin composition for sealing is heated and melted, and then the epoxy resin composition for sealing is poured into a mold, and the epoxy resin composition for sealing is further heated in the mold. . Thereby, the epoxy resin composition for sealing is thermoset and a sealing material is formed.

  When producing the sealing material by the transfer molding method, for example, the mold temperature is in the range of 160 to 185 ° C., and the molding time is in the range of 60 to 120 seconds. The molding conditions may be changed as appropriate according to the composition of the sealing epoxy resin composition.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these Examples at all.

[Preparation of epoxy resin composition for sealing]
In each example and comparative example, the inorganic filler was surface-treated with a coupling agent. The mixture was obtained by fully mixing the inorganic filler after a process, a hardening accelerator, an epoxy resin, a phenol compound, a mold release agent, and a coloring agent with a mixer. The mixture was melt-kneaded while being heated with a biaxial roll at a set temperature of 100 ° C. for 5 minutes, cooled and pulverized with a pulverizer to obtain a powdery epoxy resin composition for sealing.

The components used in Examples and Comparative Examples, and their amounts are as shown in the table below. In the table, the amounts of the components are shown in parts by mass. Details of these components are as follows.
Curing accelerator 1: San Apro Co., Ltd. MeTPP-5HIPA-THB resin MB.
Curing accelerator 2: San Apro Co., Ltd. MeTPP-5HIPA-THB.
Curing accelerator 3: manufactured by Panasonic Corporation, a reaction product of TPP-K and phenol novolac resin.
-Epoxy resin 1: manufactured by Mitsubishi Chemical Corporation, tetramethylbiphenyl type epoxy resin, product number YX-4000.
Epoxy resin 2: Nippon Kayaku Co., Ltd., biphenyl aralkyl epoxy resin, product number NC-3000.
-Phenol compound 1: Meiwa Kasei Co., Ltd. make, novolak type phenol resin, product number H-3M
-Phenol compound 2: manufactured by Meiwa Kasei Co., Ltd., biphenyl aralkyl type phenol resin, product number MEH7851SS.
Release agent 1: manufactured by Mitsubishi Chemical Corporation, α-olefin / maleic anhydride WAX, product name Diacarna 30, weight average molecular weight of about 10,000.
Mold release agent 2: manufactured by Dainichi Chemical Co., Ltd., carnauba wax, product name F1-100.
Release agent 3: manufactured by Dainichi Chemical Co., Ltd., polyethylene wax, product name PE-A.
Inorganic filler: Electrochemical Industry Co., Ltd., spherical fused silica, product name FB940.
Coupling agent: manufactured by Shin-Etsu Silicone Co., Ltd., silane coupling agent, 3-mercaptopropyltrimethoxysilane, product name KBM803.
-Pigment: Mitsubishi Chemical Corporation carbon black, product name MA-600.

  The further detail of the hardening accelerator shown in Table 1 is demonstrated.

(Curing accelerator 1)
A phosphonium salt represented by the following formula (3) synthesized by a method including a salt exchange reaction between a quaternary phosphonium alkyl carbonate and an organic carboxylic acid is obtained by masterbatching with a phenol novolac resin added during synthesis, It is a powdery curing accelerator obtained by passing a product having a phenol novolac resin ratio of 15% by mass through a mesh having an opening of 212 μm.

(Curing accelerator 2)
The phosphonium salt crystal represented by the above formula (3) synthesized by a method including a salt exchange reaction between a quaternary phosphonium alkyl carbonate and an organic carboxylic acid is pulverized and then passed through a mesh having an opening of 212 μm. It is a powdery curing accelerator obtained in 1.

(Curing accelerator 3)
By heating TPP-K and low-viscosity phenol novolak resin (Maywa Kasei Kogyo Co., Ltd., product number H-4) at 170 to 180 ° C. in a nitrogen atmosphere, cooling the resulting product, and then pulverizing it. This is a compound having a phosphonium cation concentration of 10% by mass.

[Spiral flow length]
As an index of fluidity at the time of molding, the spiral flow length of the epoxy resin composition for sealing immediately after production in Examples and Comparative Examples is a transfer press (ETA-D type) manufactured by Shindo Metal Industries, Ltd. Measurement was performed using a spiral flow measurement mold in accordance with ASTM D3123 under conditions of a mold temperature of 175 ° C., an injection pressure of 6.9 MPa, and a molding time of 120 seconds.

[Geltime evaluation]
The gel time at 170 ° C. of the epoxy resin composition for sealing obtained in each example and comparative example was measured. The measurement was performed using a curast meter manufactured by JSR Corporation. The gel time in this evaluation test is a temperature required from the start of measurement until the torque reaches 9.81 mN · m (0.1 kgf · cm).

[Continuous moldability evaluation]
After setting a substrate having a size of 40 mm × 40 mm in a plan view on a mold of a molding machine “S. Pot” manufactured by Daiichi Seiko Co., Ltd., molding an epoxy resin composition for sealing in each example and comparative example A molded body was formed on the substrate by molding at a temperature of 175 ° C. and a curing time of 150 seconds. Immediately thereafter, the molded body was removed from the mold by lifting the substrate from the mold. At this time, the force required to lift the substrate from the mold was measured using a digital force gauge “Model No. ZTS-DPU-100N” manufactured by Imada Co., Ltd. This operation was repeated 100 times, and the average value of the measured values by the digital force gauge in each case of the molding times 1 to 25, 26 to 50, 51 to 75, and 76 to 100 was calculated.

  Also, when the average of 100 measured values is 10N or less, it is determined as “A”, when it is greater than 10N and less than 20N, “B”, when it is 20N or more and less than 30N, “C”, and when 30N or more is “D” did.

[Reflow resistance evaluation 1]
After mounting a semiconductor element having a size of 8 mm × 9 mm in plan view on a substrate having a size of 35 mm × 35 mm in plan view, this substrate was set in a mold of a molding machine (model number MM-536) manufactured by Apic Yamada Co., Ltd. . Then, the sealing material which covers the semiconductor element on a board | substrate was formed by shape | molding the epoxy resin composition for sealing on the conditions of the shaping | molding temperature of 175 degreeC, and the curing time of 120 seconds. This sealing material was post-cured under the conditions of a heating temperature of 175 ° C. and a heating time of 4 hours. Thus, a semiconductor device was manufactured.

  This semiconductor device was placed in a constant temperature and humidity chamber at 30 ° C. and 60% RH for 192 hours. Subsequently, the semiconductor device was subjected to a reflow treatment at a peak temperature of 265 ° C. using a far-infrared reflow furnace “model number BABY REFLOW Ba-200D” manufactured by Asahi Electronics Co., Ltd. Then, the presence or absence of peeling of the sealing material with respect to the semiconductor element in the semiconductor device and the degree of peeling were confirmed using an ultrasonic exploration device “Model No. FS300II” manufactured by Hitachi Power Solutions Co., Ltd. As a result, “A” indicates that no peeling is observed, “B” indicates that peeling is observed, and the area of the peeling is 5% or less with respect to the surface area of the semiconductor element. The case where the area was larger than 5% with respect to the surface area of the semiconductor element was evaluated as “C”.

[Reflow resistance evaluation 2]
A semiconductor device was manufactured by the same method as in “Reflow resistance evaluation 1” above. Change the conditions in the constant temperature and humidity chamber in “Reflow resistance evaluation 1” to “60 ° C., 60% RH”, the arrangement time to “120 hours”, and perform the same treatment as in “Reflow resistance evaluation 1” and evaluate Went.

Claims (3)

A phosphonium salt (A) represented by the following formula (1);
Epoxy resin (B);
A curing agent (C);
An inorganic filler (D);
A mold release agent (E),

In equation (1),
R ^{1 to} R ³ are each independently an aryl group having 6 to 12 carbon atoms,
R ⁴ is an alkyl group having 1 to 4 carbon atoms,
R ⁶ and R ⁸ are each independently COOH or OH;
R ⁵ and R ⁷ are each independently H or an alkyl group having 1 to 4 carbon atoms,
Each of R ⁹ and R ¹¹ is H;
R ¹⁰ is COOH or OH, and p, q, and r are numbers satisfying the relationship of p ≧ 1, q ≧ 1, r ≧ 1, and q ≧ r,
The release agent (E) includes a copolymer (E1) of an α-olefin and maleic anhydride,
An epoxy resin composition for sealing.   Hardened | cured material obtained by hardening the epoxy resin composition for sealing of Claim 1. A semiconductor element;
A sealing material for sealing the semiconductor element,
The said sealing material is a semiconductor device which consists of hardened | cured material of Claim 2.