JP2015117270A - Purification method of polymer, purified polymer, and adhesive for semiconductor using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a purification method of a polymer which, even though being a simple and low-cost process, has excellent purification efficiency; a purified polymer; and an adhesive for a semiconductor using the purified polymer produced by the method.SOLUTION: Provided is a purification method of a polymer synthesized by atom transfer radical polymerization, comprising: adding (A) an organic solvent and (B) a poor solvent of the polymer to a polymer solution after polymerization and mixing the mixture; thereafter adding pure water to and stirring and standing still the mixture to separate the same into two layers including a solution layer containing the polymer and an aqueous solution layer; and extracting a halide ion and a transition metal ion remaining in the polymer into the aqueous solution layer side. Preferably, the polymer synthesized by atom transfer radical polymerization is a copolymer having a star structure where at east three polymer chains extends radially, and contains in a molecular chain at least 0.1 mol% or more cross-linking reaction group.

Description

  The present invention relates to a method for purifying a polymer synthesized by atom transfer radical polymerization, which is one of living radical polymerization methods, a polymer purified by the purification method, and a semiconductor adhesive using the same.

  In recent years, along with the miniaturization of semiconductor packages, CSP (Chip Size Package) that is the same size as a semiconductor chip, and stacked CSP in which semiconductor chips are stacked in multiple stages have become widespread (see, for example, Patent Documents 1 to 5). ). In order to perform adhesion on a package having unevenness, a performance for satisfactorily filling the unevenness is required.

One of typical semiconductor adhesives is a die bond film. Usually, a die bond film is comprised from resin and a filler, and resin is comprised combining a thermosetting component and a high molecular weight component.
As the thermosetting component, an epoxy resin is particularly preferably used from the viewpoint of heat resistance and moisture resistance, and as the high molecular weight component, a polyimide resin having a crosslinkable group, a (meth) acrylic resin, or the like is used. Among them, acrylic rubber is preferably used.

As characteristics of the die bond film, process compatibility (laminate property, dicing property, pickup property), embedding property, reliability (reflow resistance) and the like are required.
Among these, in order to satisfy the requirements for embedding, it is only necessary to increase the fluidity of the resin, specifically, to lower the viscosity at the B stage. The entanglement between each other is reduced, and the overall viscosity can be reduced.

  However, in order to satisfy the reliability requirement, the resin must have a high molecular weight, and the fluidity is lowered. In order to break through the trade-off relationship between fluidity and reliability, a solution has been made by using a star-shaped polymer (Patent Document 6).

  The star structure polymer obtained by atom transfer radical polymerization is easy to control the structure, and by applying the star structure polymer to each semiconductor-related material, it has superior physical properties compared to the linear polymer. It is known to show (Patent Documents 6 and 7).

  However, the initiator used for atom transfer radical polymerization is a halogen compound, and several hundred to several thousand ppm of halogen remains in the polymerized polymer. Among the remaining halogens, halide ions generated by the termination reaction of polymerization cause ion migration when used in semiconductor-related materials, and are cited as a cause of lowering reliability.

  Therefore, in order to use a polymer synthesized by the atom transfer radical polymerization method as a semiconductor-related material, it is necessary to remove halide ions remaining in the polymer.

  Examples of the polymer purification method include a reprecipitation method and a liquid separation purification method. The reprecipitation method is a method of purification by repeating the precipitation and re-dissolution of the polymer with a large amount of poor solvent, and the reprecipitation purification method is often used in studies on a small scale. However, the reprecipitation purification method is not suitable as an industrial purification method because of low productivity and high cost.

  The liquid separation purification method is a method in which a polymer diluted in a water-insoluble solvent is mixed and stirred with water and then left to stand to extract a residual catalyst on the aqueous layer side. For example, in Kaneka's patent, a separation and purification method using a water-insoluble alcohol is proposed, but the weight average molecular weight of the polymer being implemented is about 20,000 or less (Patent Document 8). .

  Although the separation purification method has higher productivity than the reprecipitation method, there is no example used for purification of a high molecular weight compound having a molecular weight of 50,000 or more. The reason for this is that the viscosity of the solution increases as the molecular weight increases, the polymer precipitates upon contact with the aqueous layer, and the organic layer and the aqueous layer are not clearly separated.

  Moreover, when extracting an ionic impurity to a water layer by liquid separation refinement | purification, extraction efficiency improves, so that a contact probability with a water molecule is high. For this reason, the separation and purification method having a composition in which the organic layer and the aqueous layer are clearly separated after the separation operation is contacted at a molecular level with a higher probability than separation separation purification involving polymer precipitation. In order to improve the degree of purification by the liquid, it is preferable that the two layers are clearly separated without turbidity after the liquid separation operation.

  Furthermore, when a reactive functional group exists in the polymer to be purified, it is necessary to perform the purification by a method that does not affect the functional group. For example, in the purification of a polymer containing an epoxy group, care must be taken so that an epoxy ring-opening reaction does not occur.

  Depending on the application, a high molecular weight material having a molecular weight of 50,000 or more is required, and particularly when used for a die bond film or the like, a molecular weight of 100,000 or more is preferable in order to maintain the film forming ability. Therefore, it was necessary to carry out purification of the high molecular weight more simply.

JP 2001-279197 A JP 2002-222913 A JP 2002-359346 A JP 2001-308262 A Japanese Patent Laid-Open No. 2004-072009 JP 2009-231469 A JP 2009-227793 A JP 2011-231236 A

  The present invention has been made in view of such a situation. A method for purifying a polymer and a purified polymer, which are simple in process and low in cost, and excellent in purification efficiency, and a purified polymer produced thereby. The present invention provides a semiconductor adhesive to be used.

  As a result of earnest research, the present inventor has controlled the solubility of the polymer (polymer) in each of the aqueous layer and the organic layer with alcohol or the like, which is a poor solvent for the polymer, so that the polymer is a high molecular weight polymer. However, the present inventors have found a composition in which the two layers are separated without being suspended, and have found that both lower cost and higher purification efficiency are achieved than the reprecipitation purification method, and the present invention has been achieved.

  The present invention relates to the following (1) to (11).

  (1) A method for purifying a polymer synthesized by atom transfer radical polymerization, wherein (A) an organic solvent and (B) a poor solvent for a polymer are added to and mixed with the polymer solution after polymerization, A polymer that is separated into two layers, a polymer-containing solution layer and an aqueous solution layer, by adding pure water, stirring and standing, and extracting halide ions and transition metal ions remaining in the polymer to the aqueous solution layer side Purification method.

(2) The polymer synthesized by atom transfer radical polymerization is a copolymer having a star structure in which at least three polymer chains extend radially, and at least 0.1 mol% or more of a crosslinkable reactive group in the molecular chain The method for purifying a polymer according to (1), which is a polymer to be contained.
(3) The method for purifying a polymer according to (1) or (2), wherein the organic solvent (A) is a water-insoluble organic solvent.

  (4) The method for purifying a polymer according to any one of (1) to (3), wherein the poor solvent for the polymer (B) is a water-soluble organic solvent.

  (5) The mixing ratio of (A) an organic solvent, (B) a poor polymer solvent and pure water is (A) 50 to 100 parts by mass, (B) 10 to 30 parts by mass, and pure water 20 to 60 parts by mass, respectively. The method for purifying a polymer according to any one of (1) to (4), wherein

  (6) The method for purifying a polymer according to any one of (1) to (5), wherein the poor solvent for the polymer (B) is an alcohol having 2 to 4 carbon atoms.

  (7) The polymer purification method according to any one of (1) to (6), wherein the polymer to be purified has a weight average molecular weight of 50,000 to 2,000,000.

  (8) The polymer purification method according to any one of (1) to (7), wherein the solid content in the aqueous solution layer is 3% by mass or less after stirring and standing.

(9) A purified polymer obtained by the polymer purification method according to any one of (1) to (8).
(10) The purified polymer according to (9) is a copolymer having a star structure in which at least three polymer chains extend radially, and at least 0.1 mol of a crosslinkable reactive group is added to the molecular chain. A refined polymer that is a polymer containing at least%.
(11) A semiconductor adhesive using the purified polymer according to (10) as one component of a high molecular weight component of a semiconductor adhesive comprising a thermosetting component and a high molecular weight component.

  The polymer purification method of the present invention enables separation and purification of a high molecular weight which has been difficult in the past, and can produce a high-purity polymer at a low cost with less ionic impurities than in the past. Become.

The best mode for carrying out the present invention will be described in detail below.
"Polymer to be purified"
The polymer purification method (liquid separation purification method) of the present invention can be applied to a polymer synthesized by atom transfer radical polymerization, which is a kind of living radical polymerization. However, the present invention can also be applied to polymers / polymer solutions synthesized by other synthesis methods. Specific examples of the polymer to which the liquid separation purification method of the present invention can be applied include (meth) acrylic resin, polyimide resin, urethane resin, polyphenylene ether resin, epoxy resin, phenol resin, silicone resin, and polyetherimide resin. , Phenoxy resin, modified polyphenylene ether resin, polyimide resin, polyamide resin, fluororesin, various modified resins, etc., but the examples shown here are only examples and may be peptides or polymers having a weight average molecular weight of 5000 or more. For example, the structure is not particularly limited.

  The weight average molecular weight of the polymer to be purified is 5,000 to 2,000,000, preferably 20,000 to 150,000, and more preferably 50,000 to 1,000,000.

[(A) Organic solvent]
The (A) organic solvent used in the present invention is preferably a water-insoluble organic solvent, and the water-insoluble organic solvent has a purity of 30% by mass or less at a temperature during stirring and standing. It is preferably 20% by mass or less, and more preferably 10% by mass or less. When the solubility in water exceeds 30% by mass, the two-layer separation of the water / organic layer may be inhibited.

  The water-insoluble organic solvent in the present invention refers to a polymer that can dissolve 5% by mass or more of the polymer to be purified, preferably 20% by mass or more, and more preferably 50% by mass or more. If the polymer to be purified can only be dissolved in less than 5% by mass, the recovered polymer solution has a low NV (non-volatile content), so a large amount of organic solvent is required, and the distillation time becomes longer, resulting in a lower cost. Can be high.

  The boiling point of the water-insoluble organic solvent in the present invention is preferably 300 ° C. or less, more preferably 200 ° C. or less, and further preferably 100 ° C. or less. The higher the boiling point, the longer the distillation temperature and time, and the higher the cost.

  The addition amount of the water-insoluble organic solvent is 1 to 5 times by mass, preferably 1.5 to 4 times by mass, more preferably 2 to 3 times by mass with respect to the polymerization solution. Is more preferable. If the addition amount is too small, separation of the aqueous layer / organic layer is hindered, and if it is too much, the cost increases.

"(B) Polymer poor solvent"
The poor polymer solvent used in the present invention can be used regardless of its structure as long as it is a water-soluble polymer poor solvent. As an example, a low-boiling point aliphatic alcohol is preferably used because it can be easily removed by distillation under reduced pressure later.

As a poor solvent for the polymer, an alcohol having 1 to 10 carbon atoms is used, preferably 2 to 6 carbon atoms, and more preferably 2 to 4 carbon atoms.
Examples of the alcohol having 1 to 10 carbon atoms include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, pentyl alcohol, sec-pentyl alcohol, t-pentyl alcohol, hexyl alcohol, sec-hexyl alcohol, heptyl alcohol, Examples include octyl alcohol, nonyl alcohol, deca alcohol and isomers thereof.

  The amount of the poor polymer solvent added is 0.05 to 2 parts by mass, preferably 0.1 to 1.5 parts by mass, with respect to the amount of the water-insoluble organic solvent. It is more preferably 2 to 0.8 times by mass. If the amount of the poor solvent to be added is small, the separation of the aqueous layer and the organic layer is inhibited, and if it is too large, the polymer may be precipitated.

  After stirring and standing, the solid content contained in the aqueous phase layer after phase separation is preferably 10% by mass or less, and more preferably 3% by mass or less. When the solid content exceeding 10 mass is contained in the aqueous solution, it is considered that the high molecular weight obtained by purification is reduced, the cost is increased, and the purification degree is reduced.

The polymer purification method (separation purification) in the present invention may further use a solvent other than (A) an organic solvent and (B) a polymer poor solvent used for purification. For the purpose of improving the separation speed, for example, a second component of a water-insoluble organic solvent such as toluene can be added to such an extent that the separability is not affected.
In the liquid separation purification in the present invention, chemical substances other than the solvents (A) and (B) may be added. For example, for the purpose of improving the water-solubility of copper and halogen and enhancing the purification effect, an organic substance having a functional group that coordinates with a chelating agent or a metal can be added to such an extent that the separability is not affected.

  Below, the star-shaped copolymer synthesize | combined by the atom transfer radical polymerization which is one of the living radical polymerization which is one of the purification objects of this invention is explained in full detail. The polymer to be purified in the present invention does not necessarily have to be synthesized by living radical polymerization. A general acrylic rubber having a weight average molecular weight of 300,000 to 800,000 (for example, HTR-P860 manufactured by Nagase ChemteX Corporation) can be purified using the present invention.

"Living radical polymerization"
The polymer initiator structure synthesized by living radical polymerization according to the present invention has a structure represented by the general formula (I).

In general formula (I), R ₁ represents a monovalent organic group having an arbitrary structure, X represents a halogen atom such as fluorine, chlorine, bromine, etc., preferably chlorine and bromine, and more preferably bromine. n represents an integer of 1 to 20. R ₂ and R ₃ each represent a hydrogen atom and an aliphatic group having 1 to 20 carbon atoms. Specific examples of the aliphatic group include an alkyl group having 1 to 10 carbon atoms and an alkoxyalkyl group. A linear or branched chain may be used, and a linear alkyl group having 1 to 5 carbon atoms is preferable, and a linear alkyl group having 1 to 3 carbon atoms is more preferable. Specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, cyclohexyl group, heptyl group, octyl group, 2 -Ethylhexyl group, nonyl group, decyl group, dodecyl group, stearyl group, 2-methoxyethyl group, 2-ethoxyethyl group, 2-propoxyethyl group, 2-butoxyethyl group, 3-methoxypropyl group, 3-methoxybutyl Group, 4-methoxybutyl group, 2-hydroxyethyl group, 2-hydroxypropyl group and the like.

[Star copolymer]
A star-shaped copolymer has characteristics of high fluidity and low viscosity as compared with a linear polymer having the same molecular weight. This is because the molecular chain of a linear polymer becomes longer as the molecular weight increases, and entanglement occurs between adjacent molecules, but the star copolymer has a structure in which the polymer chain extends radially from the center. It is presumed that there is an excluded volume part, and the polymer chain part does not become longer as the linear polymer, and the occurrence of entanglement is less. That is, it is considered that the fluidity at the same molecular weight improves as the number of branched chains increases.

The star copolymer purified by using the purification method of the present invention is a copolymer having a star structure in which at least three polymer chains extend radially and having a glass transition point of 60 ° C. or lower. (Meth) acrylic resin, polyimide resin, urethane resin, polyphenylene ether resin, polyetherimide resin, phenoxy resin, modified polyphenylene ether resin, and the like, among which acrylic rubber is preferable.
The star copolymer preferably has a glass transition point Tg of 60 ° C. or lower, more preferably 50 ° C. or lower, more preferably from the viewpoint of fluidity of the resin blend and toughness of the cured product. Is 40 ° C. or lower.

  The acrylic rubber is a rubber mainly composed of an acrylate ester and mainly composed of a copolymer such as butyl acrylate and acrylonitrile or a copolymer such as ethyl acrylate and acrylonitrile. In the present invention, as described above, Has a star structure.

  The weight average molecular weight of the star copolymer is preferably 30000 to 3000000, more preferably 60000 to 1000000, and 100000 to 800000, from the viewpoint of obtaining high reliability as a die bond film. Is more preferable. In addition, a weight average molecular weight is a polystyrene conversion value using the calibration curve by a standard polystyrene by the gel permeation chromatography method (GPC). In this case, the weight average molecular weight of each polymer chain is preferably 10,000 to 300,000, more preferably 30,000 to 200,000, and further preferably 50,000 to 150,000. The weight average molecular weight of each polymer chain is a value obtained by dividing the weight average molecular weight of the whole molecule by the number of polymer chains. When the star copolymers having the same weight average molecular weight are composed of similar monomers, the greater the number of polymer chains, the shorter the polymer chains per one, so that the fluidity is improved. As a result, it is thought that it becomes a low viscosity. Therefore, when it is desired to keep the weight average molecular weight as it is and to lower the viscosity, the viscosity can be lowered by increasing the number of polymer chains.

Hereinafter, specific examples of the star copolymer and an example of the synthesis method thereof will be described. However, the target polymer by the purification method of the present invention is not limited to the following synthesis method.
A star-shaped copolymer, for example, atom-transfers two or more monomer species by using a halogen compound, an amine compound as a ligand, and a transition metal of Group 7 to 11 elements of the periodic table as a catalyst. It can be synthesized by polymerization by radical polymerization.
Hereinafter, each component used in the synthesis method will be described.

[Monomer species]
The monomer species is not particularly limited, and various types can be used. For example, the following monomers can be mentioned. In addition, although the following structural formula shows an acryl-type thing, a methacryl-type thing can also be used. That is, in the structures (1) to (7), those in which CH ₂ ═CH— is replaced with CH ₂ ═C (CH ₃ ) — can also be used.

R in the above (1) represents an aliphatic group having 1 to 20 carbon atoms or an aromatic group having 6 to 20 carbon atoms. Specific examples of the aliphatic group include alkyl having 1 to 20 carbon atoms. Represents a group or an alkoxyalkyl group, and may be linear or branched. Among them, a linear alkyl group having 1 to 10 carbon atoms is preferable, and a linear alkyl group having 2 to 8 carbon atoms is more preferable.
Specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, cyclohexyl group, heptyl group, octyl group, 2 -Ethylhexyl group, nonyl group, decyl group, dodecyl group, stearyl group, 2-methoxyethyl group, 2-ethoxyethyl group, 2-propoxyethyl group, 2-butoxyethyl group, 3-methoxypropyl group, 3-methoxybutyl Group, 4-methoxybutyl group, 2-hydroxyethyl group, 2-hydroxypropyl group and the like.
On the other hand, the aromatic group represents an aryl group having 6 to 20 carbon atoms and an aralkyl group having 7 to 20 carbon atoms, and among them, an aryl group having 6 to 10 carbon atoms and an aralkyl group having 7 to 11 carbon atoms are preferable. Specific examples include a phenyl group, a toluyl group, and a benzyl group.

  R in the above (3) represents H, an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom, and among them, H or an aliphatic hydrocarbon group having 1 to 3 carbon atoms or a halogen atom is preferable. Or a C1-C2 aliphatic hydrocarbon group or a halogen atom is more preferable. For example, it represents an alkyl group having 1 to 5 carbon atoms, chlorine, and bromine, and more specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a pentyl group, and the like.

R ¹ and R ^{2 in} (4) each represent H or an aliphatic hydrocarbon group having 1 to 4 carbon atoms. Among these, H or an aliphatic hydrocarbon group having 1 to 3 carbon atoms is preferable. For example, it represents an alkyl group having 1 to 4 carbon atoms, and more specifically includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and the like. Moreover, the alkyl group which R < ¹ >, R < ² > represents may be substituted by the amino group.

R ^{1 in the} above (5) represents a divalent aliphatic hydrocarbon group having 1 to 4 carbon atoms, and the aliphatic hydrocarbon group having 1 to 4 carbon atoms represented by R ¹ is, among others, 1 carbon atom. ~ 2 aliphatic hydrocarbon groups are preferred. For example, it represents an alkylene group having 1 to 4 carbon atoms, and more specifically includes a methylene group, an ethylene group, a propylene group, and the like. R ² and R ³ each represent H, an aliphatic hydrocarbon group having 1 to 4 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms. Of these, an aliphatic hydrocarbon group having 1 to 2 carbon atoms is preferable. For example, it represents an alkyl group having 1 to 4 carbon atoms, and more specifically includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and the like. Specific examples of the aromatic hydrocarbon group having 6 to 10 carbon atoms include a phenyl group, a toluyl group, and a benzyl group.

R ^{1 in the} above (7) represents a divalent aliphatic hydrocarbon group having 1 to 5 carbon atoms, and among them, an aliphatic hydrocarbon group having 2 to 4 carbon atoms is preferable. For example, it represents an alkylene group having 1 to 5 carbon atoms, and more specifically includes a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and the like. R ² , R ³ and R ⁴ each represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms and an alkoxy group having 1 to 5 carbon atoms. Among these, an aliphatic hydrocarbon group having 1 to 4 carbon atoms is preferable, and an aliphatic hydrocarbon group having 2 to 3 carbon atoms is more preferable. For example, an alkyl group having 1 to 5 carbon atoms is represented, and more specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a pentyl group, and the like can be given. Specific examples of the alkoxy group having 1 to 5 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.

  Among the (1) to (7), ethyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylonitrile are preferable. The expression “(meth) acrylic acid” indicates acrylic acid and / or methacrylic acid.

  Moreover, as a monomer species used for the polymer to be purified in the present invention, a monomer having a crosslinkable functional group can also be suitably used. Examples thereof are shown below, but the present invention is not limited to the following.

In the above (8) and (9), R ¹ represents a divalent aliphatic hydrocarbon group having 1 to 5 carbon atoms, and examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, and a pentylene group. Of these, a methylene group is preferred. The above (8) and (9) are acrylate-based examples, but methacrylate-based ones can also be used. That is, in (8) and (9), those in which CH ₂ ═CH— is replaced with CH ₂ ═C (CH ₃ ) — can be used. In the above (8) to (10), glycidyl (meth) acrylate is preferred.

  It is preferable to use (meth) acrylonitrile as one of the above monomer types (1) to (10). Moreover, it is preferable to use the monomer which has a crosslinkable functional group as at least 1 sort (s). Specific examples of the combination preferably include n-butyl (meth) acrylate, ethyl (meth) acrylate, glycidyl (meth) acrylate, (meth) acrylonitrile, methyl acrylate, propyl acrylate, and the like. be able to.

The blending amount of the monomer is not particularly limited and can be freely set except for (meth) acrylonitrile and amino group-containing monomers. In the present invention, the blending amount of the acrylonitrile or amino group-containing monomer can be 10% or more, preferably 20% or more, more preferably 30% or more, in terms of molar fraction with respect to the total amount of the monomer species used. Preferably, 40% or more is more preferable, and the upper limit is approximately 60%. In addition, the following monomers etc. are used suitably as an amino group containing monomer here. In addition, R in the following monomers represent -CH ₃ or _-C 2 _{H 5.}

  The amount of the polyfunctional initiator used is preferably 200: 1 to 20000: 1 in molar ratio with respect to the monomer.

[Ligand]
The ligand in this synthesis method is an amine compound, and it is preferable to use an amine compound having two or more N atoms in one molecule. Examples of such amine compounds include the following.

（Ｒ^１は、炭素数１〜３の２価の脂肪族炭化水素基を示し、Ｒ^２、Ｒ^３は、ぞれぞれＨ又は炭素数１〜３の脂肪族炭化水素基を示す。）

(R ¹ represents a divalent aliphatic hydrocarbon group having 1 to 3 carbon atoms, and R ² and R ³ each represent H or an aliphatic hydrocarbon group having 1 to 3 carbon atoms.)

Examples of the divalent aliphatic hydrocarbon group having 1 to 3 carbon atoms represented by R ¹ include a methylene group, an ethylene group, and a propylene group. Examples of the aliphatic hydrocarbon group having 1 to 3 carbon atoms represented by R ² and R ³ include a methyl group, an ethyl group, and a propyl group.

  As a usage-amount of a ligand, it is preferable that it is 0.5: 1-2: 1 by molar ratio with respect to the metal to be used.

[catalyst]
The catalyst used in this synthesis method is a transition metal of Group 7 to 11 elements of the periodic table, specifically, manganese, technetium, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, Examples include palladium, platinum, copper, silver, and gold. Among these, copper, ruthenium, nickel, and iron are preferable, and copper is most preferable. In particular, when copper is used, the catalytic activity is high, and it is easy to achieve a high polymerization rate and a high molecular weight.

  As a usage-amount of a catalyst, it is preferable that it is 1: 0.5-1: 10 by molar ratio with respect to an initiator.

[solvent]
Solvents that can be used in this synthesis method include hydrocarbon solvents such as dimethyl sulfoxide (DMSO), benzene and toluene, ether solvents such as diethyl ether, tetrahydrofuran and dioxane, and halogenated hydrocarbons such as methylene chloride and chloroform. Solvents, ketone solvents such as acetone and methyl ethyl ketone, alcohol solvents such as methanol, ethanol, propanol and isopropanol, nitrile solvents such as acetonitrile, propionitrile and benzonitrile, ester solvents such as ethyl acetate and butyl acetate, ethylene Carbonate solvents such as carbonate and propylene carbonate, amide solvents such as dimethylformamide, dimethylacetamide, and hexamethylphosphoric amide can be preferably used. These may be used alone or in combination. However, the examples given here are merely examples, and the present invention is not limited to these examples.

  The present invention has a feature that a solution after polymerization is filtered and liquid separation purification can be performed immediately thereafter. At the time of filtration, it is possible to dilute with a good polymer solvent such as acetone, and the concentration of the polymer at this time is 10 to 90% by mass of NV (non-volatile content), and 15 to 70% by mass. It is preferable that it is 20-50 mass%. If it is the above-mentioned concentration range, the liquid separation composition of the present invention can be applied to separate the aqueous layer and the organic layer into two layers without suspension.

[Other ingredients]
Other components used in the polymer purification method (separation purification method) of the present invention include an organic acid (for example, p-toluenesulfonic acid) for enhancing the purification effect, or an inorganic salt (for example, magnesium sulfate). ), Or a reducing agent (for example, ascorbic acid or the like) or a water-insoluble organic solvent (for example, toluene or the like) for improving the separability can be added. Further, the above-described components may be mixed at the time of polymerization, and the timing of addition does not matter.

[Atom transfer radical polymerization]
The atom transfer radical polymerization employed in the synthesis of the star copolymer, which is one of the purification targets of the present invention, polymerizes acrylic monomers using a halogen compound or the like as an initiator and a transition metal as a catalyst. This is a polymerization method, and although it is radical polymerization, a side reaction such as termination reaction hardly occurs and a polymer having a narrow molecular weight distribution (Mw / Mn = 1.1 to 2.2) can be obtained, and the charging ratio of the monomer and the initiator In addition to the characteristics of the “living radical polymerization method” in which the molecular weight of the polymer to be produced can be freely controlled, it has a halogen which is relatively advantageous for the functional group conversion reaction at the terminal, and is suitable for initiators and catalysts. Since the degree of freedom in design is large, it is useful as a method for producing a polymer having a specific functional group. As this atom transfer radical polymerization method, for example, Macromolecules, 1995, 28, 1721, 7901, Matyjazewski et al., Journal of American Chemical Society (J. Am. Chem. Soc). 1995) 117, 5614, Science 1996, 272, 866, WO 96/30421 pamphlet, WO 97/18247 pamphlet, WO 98/01480 pamphlet. , WO98 / 40415 pamphlet, JP-A-9-208616, JP-A-8-41117, and the like.

  Next, a procedure for synthesizing and purifying a star copolymer, which is one of the purification targets of the present invention, will be described.

  First, the catalyst is weighed in a container prepared for synthesis, the container is evacuated and under a nitrogen atmosphere, and each monomer species, ligand, and solvent are added. Next, nitrogen is bubbled for deoxygenation. Under a nitrogen atmosphere again, a separately prepared initiator solution is added to proceed the polymerization. The temperature at this time is about 10 to 100 ° C.

  In this synthesis method, it is important to remove oxygen and moisture in the polymerization. Moreover, in order to advance a polymerization reaction smoothly, it is important to raise the purity of a monomer, an initiator, a ligand, a metal, and a solvent.

  The solution after polymerization is filtered to remove the remaining copper powder. Thereafter, a liquid separation purification operation is performed based on the composition of the present invention to obtain a target star copolymer.

The adhesive for semiconductors of the present invention uses a copolymer comprising a thermosetting component and a high molecular weight component, and having a star structure in which at least three polymer chains extend radially as one component of the high molecular weight component. The molecular chain of the copolymer having the star structure contains at least 0.1 mol% of crosslinkable reactive groups.
As thermosetting component, epoxy resin, phenol resin, urea resin, melamine resin, alkyd resin, acrylic resin, unsaturated polyester resin, diallyl phthalate resin, silicone resin, resin synthesized from cyclopentadiene, tris (2-hydroxyethyl) Thermosetting resin containing isocyanurate, resin synthesized from aromatic nitrile, trimerized aromatic dicyanamide resin, resin containing triallyl trimetallate, furan resin, ketone resin, xylene resin, condensed polycyclic aromatic Resin, benzocyclobutene resin and the like can be used, and epoxy resin is particularly preferable. When an epoxy resin is used, it is preferable to use a curing agent and a curing accelerator.
As the high molecular weight component, a copolymer having a star structure in which at least three polymer chains extend radially, may be used in combination with other high molecular weight components. Examples of other high molecular weight components include polyimide resins, (meth) acrylic resins, urethane resins, polyphenylene ether resins, polyetherimide resins, phenoxy resins, modified polyphenylene ether resins, and acrylic rubber.
In addition to the thermosetting component and the high molecular weight component, the semiconductor adhesive may contain a curing agent, a curing accelerator, a coupling agent, a filler, and the like.
A die bond film is generally used as an adhesive for a semiconductor, and it can be used as an adhesive between semiconductor elements or between a semiconductor element and a substrate for mounting a semiconductor element. Further, it can be used as an interlayer adhesive insulating layer.
Below, the adhesive agent for semiconductors is demonstrated for the example of the die-bonding film which used the epoxy resin as a thermosetting component.

[Epoxy resin]
A die bond film is mentioned as an adhesive for semiconductors according to the present invention. The die bond film contains an epoxy resin as a curable component. The epoxy resin is not particularly limited as long as it is cured and has an adhesive action. Bifunctional epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin, novolac type epoxy resins such as phenol novolac type epoxy resin and cresol novolak type epoxy resin, and the like can be used. Moreover, what is generally known, such as a polyfunctional epoxy resin, a glycidyl amine type epoxy resin, a heterocyclic ring-containing epoxy resin, or an alicyclic epoxy resin, can be applied.

  In particular, the molecular weight of the epoxy resin is preferably 1000 or less, and more preferably 500 or less, in view of the high flexibility of the film in the B stage state. Further, 50 to 90 parts by mass of a bisphenol A type or bisphenol F type epoxy resin having a molecular weight of 500 or less excellent in flexibility, and 10 to 50% by mass of a polyfunctional epoxy resin having a molecular weight of 800 to 3000 excellent in heat resistance of the cured product, It is also preferable to use together.

[Curing agent]
As the curing agent for the epoxy resin, known curing agents that are generally used can be used. For example, amines, polyamides, acid anhydrides, polysulfides, boron trifluoride, bisphenol A, bisphenol F, bisphenol S. Examples thereof include bisphenols having two or more phenolic hydroxyl groups per molecule, phenol novolac resins, xylylene-modified phenol resins, bisphenol A novolac resins, cresol novolac resins, and other phenol resins.

On the other hand, in this invention, when the compatibility in the state of a varnish before die-bonding film preparation deteriorates, it can improve by changing the hardening | curing agent of an epoxy resin to a predetermined thing. Examples of the predetermined curing agent include those having a softening temperature of 150 ° C. or lower (preferably 140 ° C. or lower, more preferably 130 ° C. or lower).
Specific examples include phenol novolac resins, phenol aralkyl resins, cresol novolak resins, naphthol aralkyl resins, triphenolmethane resins, terpene modified phenol resins, dicyclopentadiene modified phenol resins, among others, phenol novolac resins, phenol aralkyls. Resins are preferred. As content of a hardening | curing agent, it is preferable to mix | blend by 0.5-2 as an equivalent ratio of the number of epoxy groups of all the epoxy resins, and the number of hydroxyl groups of all the hardening | curing agents.

[Filler]
Furthermore, the die bond film according to the present invention is intended to improve the dicing property of the adhesive film in the B-stage state, improve the handleability of the adhesive film, improve the thermal conductivity, adjust the melt viscosity, and impart thixotropic properties. It is preferable to add a filler, more preferably an inorganic filler.

  Inorganic fillers include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, alumina, aluminum nitride, aluminum borate whisker, boron nitride, crystalline silica, non Examples thereof include crystalline silica and antimony oxide. In order to improve thermal conductivity, alumina, aluminum nitride, boron nitride, crystalline silica, amorphous silica and the like are preferable. For the purpose of adjusting melt viscosity and imparting thixotropic properties, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, alumina, crystalline silica, non-crystalline silica Crystalline silica and the like are preferred. In order to improve dicing properties, alumina and silica are preferable.

  In the present invention, containing 40 to 180 parts by mass of the filler with respect to 100 parts by mass of the resin improves the dicing property, and the storage elastic modulus after curing of the adhesive film becomes 20 to 600 MPa at 170 ° C., It is preferable at the point from which wire-bonding property becomes favorable, It is more preferable that it is 60-160 mass parts, It is further more preferable that it is 60-120 mass parts.

[Content of each component]
The content of each component is 10 to 40 parts by mass of the copolymer having the star structure, 30 to 45 parts by mass of the epoxy resin and the curing agent, and the filler includes the copolymer and the copolymer. It is preferable that it is 40-180 mass parts with respect to a total of 100 mass parts of the said epoxy resin and the said hardening | curing agent.
By setting the content of each component within the above numerical range, it is possible to bury the unevenness and ensure insulation from the semiconductor element (chip). Further, the content of each component is preferably 12 to 35 parts by mass of the copolymer, 33 to 42 parts by mass of the epoxy resin and the curing agent, and the filler and the copolymer. It is 60-160 mass parts with respect to a total of 100 mass parts of an epoxy resin and the said hardening | curing agent, More preferably, the said copolymer is 15-30 mass parts, and the said epoxy resin and hardening | curing agent are 35-35 mass parts. 40 parts by mass, and the filler is 60 to 120 parts by mass with respect to 100 parts by mass in total of the copolymer, the epoxy resin, and the curing agent.

[Other ingredients]
The die bond film according to the present invention may contain, as other components, a silane coupling agent, a titanium coupling agent, a curing accelerator, a leveling agent, an antioxidant, an ion trapping agent, and the like.

<Production of die bond film>
Next, each process for producing a die bond film will be described. The process shown below is an example, and the die bond film is not limited to the following process.
(1) Preparation of varnish The varnish is prepared by mixing and kneading the high molecular weight component, a thermosetting component mainly composed of an epoxy resin, a filler, and other components in an organic solvent.
The organic solvent used for preparing the varnish is not particularly limited as long as it can uniformly dissolve, knead or disperse the material, and conventionally known ones can be used. Examples of such a solvent include ketone solvents such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, acetone, methyl ethyl ketone, and cyclohexanone, toluene, xylene, and the like. It is preferable to use methyl ethyl ketone, cyclohexanone, etc. in terms of fast drying speed and low price.

  There is no restriction | limiting in particular in the usage-amount of the organic solvent at the time of using for preparation of a varnish, Although an organic solvent is removed from a die-bonding film by heat drying etc., the amount of organic solvents (residual volatile matter) after die-bonding film preparation Is preferably 0.01 to 3% by mass based on the total mass, more preferably 0.01 to 2% by mass based on the total mass from the viewpoint of heat resistance reliability, and 0.01 to 1.5% by mass based on the total mass. Is more preferable.

  The above mixing and kneading can be carried out by appropriately combining dispersers such as a normal stirrer, a raking machine, a triple roll, and a ball mill.

(2) Coating to base material The varnish obtained by said (1) is coated on a base material, and the layer of a varnish is formed. As the substrate, a polyethylene terephthalate film, a polyimide film, a polyester film, a polypropylene film, a polyetherimide film, a polyether naphthalate film, a methylpentene film, or the like can be used.
At the time of coating, a polyethylene terephthalate film, a polyimide film or the like can be used as a base material as described above, and the coating thickness is determined in consideration of the final die bond film thickness. It is preferable to be set to ˜250 μm.

(3) Heat-drying The base material which apply | coated the varnish obtained by said (2) is heat-dried. The conditions for the heat drying are not particularly limited as long as the solvent used is sufficiently volatilized, but it is usually performed by heating at 60 to 200 ° C. for 0.1 to 90 minutes. After heat drying, the substrate can be removed to obtain a die bond film (B stage film).

  The thickness of the die bond film is preferably 5 to 250 μm in order to be able to fill irregularities such as gold wires attached to the wiring circuit of the substrate and the semiconductor element (chip) in the lower layer. When the thickness is less than 5 μm, the stress relaxation effect and adhesiveness tend to be poor. When the thickness exceeds 250 μm, the thickness is not economical and the demand for downsizing of the semiconductor device cannot be met. In addition, 20-100 micrometers is more preferable at the point which has high adhesiveness and can make a semiconductor device thin, More preferably, it is 40-80 micrometers.

  The die-bonding film according to the present invention needs to have a melt viscosity so that the substrate or the like and a semiconductor element (chip) can be bonded by thermocompression bonding, and the die-bonding film can fill the unevenness of the substrate surface and the hollow wire. The melt viscosity at 100 ° C. of the previous (B-stage state) adhesive film is preferably 100 Pa · s or more and 2500 Pa · s or less from the viewpoint of excellent irregularities on the substrate surface and the filling property of the hollow wire, and further 200 to 1500 Pa. · It is preferably s, more preferably 300 to 1300 Pa · s.

  In the die bond film according to the present invention, the melt viscosity can be obtained by measuring and calculating the die bond film before curing by a disk flow method and a rotary viscoelasticity measuring device described later.

  The die bond film according to the present invention preferably has a tack strength before curing (B stage state) of 78.4 to 294 mN (8 to 30 gf) at 25 ° C. and 392 to 784 mN (40 to 80 gf) at 40 ° C. However, at 60 ° C., 588 to 2940 mN (60 to 300 gf) and even at 80 ° C., 588 to 2940 mN (60 to 300 gf) have less stickiness at room temperature (25 ° C.) and excellent workability. This is preferable in that it is sticky at 60 ° C. or higher and has excellent laminate processability.

  The die bond film according to the present invention needs to have a specific storage elastic modulus in order to improve processability. In the present invention, the dynamic viscoelasticity measurement of the adhesive film before curing (B stage state) at 25 ° C. When the storage elastic modulus is from 200 to 3000 MPa, the dicing property is preferable. 500 to 2000 MPa is more preferable in terms of excellent dicing properties and excellent adhesion to the wafer. Further, when the storage elastic modulus of the adhesive film before curing (B stage state) measured by dynamic viscoelasticity at 80 ° C. is 0.1 to 10 MPa, it can be laminated on the wafer at 80 ° C. In particular, 0.5 to 5 MPa is more preferable in terms of high adhesion to the wafer.

  Furthermore, in the die-bonding film according to the present invention, the storage elastic modulus by dynamic viscoelasticity measurement at 260 ° C. of the die-bonding film after curing (C stage state) is 5 to 200 MPa in order to obtain good wire bonding properties. Is preferred. The storage elastic modulus is more preferably 10 to 150 MPa, still more preferably 20 to 100 MPa.

  The die bond film according to the present invention may be used not only as a single layer but also as a multilayer structure, for example, a laminate of two or more of the above-described die bond films, or the die bond film according to the present invention and other die bonds. A plurality of laminated films may be used. When laminating the die bond film according to the present invention and the other die bond film, the die bond film according to the present invention is preferably on the dicing tape side.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

[Example 1]
First, a ligand and a tetrafunctional initiator necessary for the synthesis of a four-chain star acrylic rubber were synthesized as follows.
(Synthesis of ligand)
A Dimroth equipped with a three-way cock and a septum mule were attached to a 50 ml two-necked eggplant flask and placed in an N ₂ atmosphere, and then 25.0 ml (521.4 mmol) of formic acid was weighed.
After cooling to 0 ° C., 10.0 ml (123.2 mmol) of formaldehyde was added, and the mixture was stirred at 0 ° C. for 1 hour. To this reaction solution, an aqueous solution prepared by dissolving 1.5 ml (10.0 mmol) of tris (2-aminoethyl) amine in 5 ml of distilled water was dropped over about 10 minutes. Then, the reaction liquid was returned to room temperature (25 degreeC), and it was under nitrogen stream. Next, this reactor was installed in an oil bath set at 95 ° C. and gently refluxed for 10 hours. Subsequently, after returning to room temperature and removing the solvent with an evaporator, the residue was treated with a saturated aqueous NaOH solution. The organic layer was extracted, dried over magnesium sulfate, the solvent was distilled off under reduced pressure, and 1.9 g of hexamethylated tris (2-aminoethyl) amine (hereinafter referred to as Me ₆ TREN) as a light yellow liquid (yield) 86%).
The structure was confirmed by ¹ H, ¹³ C-NMR.

(Synthesis of tetrafunctional initiator)
TekP-4HBPA (2,2-bis [4,4-bis (4-hydroxyphenyl) -cyclohexylpropane]) 5.0 g (8.7 mmol) was weighed in a 500 ml four-necked flask equipped with a three-way cock. . 100 g of THF (tetrahydrofuran) and 3.7 g (36.6 mmol) of Et ₃ N (triethylamine) were added and cooled to 0 ° C. under N ₂ atmosphere. After dropping 7.9 g (36.6 mmol) of 2-bromopropionyl bromide (3 g / min), the mixture was returned to room temperature and reacted for 12 hours. The reaction was traced using TLC (Thin Layer Chromatography), and when the spot of the raw material disappeared, the reaction was regarded as completed. After completion of the reaction, Et ₃ N bromate in the solution was removed by filtration, and the solvent was removed with an evaporator. The residue was washed twice with pure water and then dried in a vacuum dryer for 2 hours. The dried sample was recrystallized with ethanol to obtain 19.5 g (yield 50%) of a white solid compound. The structure was confirmed by ¹ H NMR.

(Synthesis of star-shaped acrylic rubber)
0.0457 g (1.44 mmol) of copper powder (hereinafter referred to as Cu (0)) was weighed into a 300 ml three-necked flask equipped with a three-way cock.
29.85 g (232.89 mmol) of butyl acrylate (hereinafter referred to as BA), 22.23 g (222.03 mmol) of ethyl acrylate (hereinafter referred to as EA), 2.31 g of glycidyl methacrylate (hereinafter referred to as GMA) (16 .25 mmol), 22.74 g (428.57 mmol) of acrylonitrile, 97.18 g of dehydrated dimethyl sulfoxide (hereinafter referred to as DMSO), and 0.1037 g (0.45 mmol) of Me ₆ TREN were added. The solution was deoxygenated by N ₂ bubbling (500 ml / min 60 min), 0.2389 g (0.45 mmol) of the above tetrafunctional initiator was added, and further N ₂ bubbling (500 ml / min 15 min) was performed. The container was closed and placed in a water bath at a set temperature of 30 ° C., and the reaction was allowed to proceed for 16 hours.

"Separation method"
After completion of the reaction, the polymer solution was diluted with dimethyl sulfoxide so that the solid content was 30% by mass, and suction filtered. To 100 g of filtrate, (A) 200 g of ethyl acetate as an organic solvent and (B) 50 g of 1-propanol as a poor solvent for the polymer were added and stirred, and then 100 g of pure water was added and stirred at 150 rpm (rotation / min) for 30 min. The stirring was stopped and the mixture was allowed to stand to separate into two layers, an aqueous layer and an organic layer. The separated organic layer (polymer solution) was recovered, cyclohexanone was added, and the low boiling point solvent was mainly removed by distillation under reduced pressure to obtain a star acrylic rubber solution.

Next, varnish was prepared as follows using the obtained polymer star acrylic rubber.
<Preparation of varnish>
As a high molecular weight component synthesized as described above, 17.9 g of star acrylic rubber, 29.0 g of bisphenol F type epoxy resin (manufactured by Tohto Kasei Co., Ltd., YDF-8170C) as a thermosetting component, cresol novolak type epoxy resin (Tohto) 9.7 g of Kasei Co., Ltd., YDCN-703), 33.8 g of xylene-modified novolak (Mitsui Chemical Co., Ltd., XLC-LL) as a curing agent, curing accelerator (Shikoku Kasei Kogyo Co., Ltd., 2PZ-CN; 1 -Cyanoethyl-2-phenylimidazole) 0.1 g, coupling agent (Nihon Unicar Co., Ltd., A-189; γ-mercapto-propyltrimethoxysilane) 0.3 g and (Nihon Unicar Co., Ltd., A-1160; (3-ureidopropyltriethoxysilane) 0.5 g and cyclohexanone Was added, and the mixture was stirred and degassed to prepare a semiconductor adhesive varnish. The softening temperature of the phenol curing agent is 76.5 ° C.

<Die bond film coating>
Using an applicator automatic coating machine (manufactured by Tester Sangyo Co., Ltd.), the varnish prepared on a PET base material (A53 manufactured by Teijin DuPont Co., Ltd.) was applied, and coating was performed with an applicator in which the gap was adjusted. The obtained film was heat-dried in an oven at 120 ° C. for 20 minutes. Thereafter, the PET substrate was peeled off to obtain a B-stage die-bonding film (semiconductor adhesive) having a thickness of 40 μm.

<Post-curing of die bond film>
The obtained B-stage die-bonding film was heat-cured in an oven at 120 ° C., 30 min, 140 ° C., 1 h, 175 ° C., 2 h to obtain a C-stage die-bonding film.

[Comparative Example 1]
In the “liquid separation purification method” in Example 1, the liquid separation operation was performed without adding 1-propanol, which is a poor solvent for the polymer (B). A star-shaped acrylic rubber was purified in the same manner as in Example 1 except that the varnish was adjusted using this, and a die bond film was produced.

[Comparative Example 2]
In the “liquid separation purification method” of Example 1, (B) 1-propanol, which is a poor polymer solvent, was not added, and (A) the weight of ethyl acetate, which is an organic solvent, was doubled to perform a liquid separation operation. . A star-shaped acrylic rubber was purified in the same manner as in Example 1 except that the varnish was adjusted using this, and a die bond film was produced.

[Comparative Example 3]
In the “liquid separation purification method” of Example 1, 1-propanol was not added, and the liquid separation operation was performed with the ethyl acetate weight being tripled. A star-shaped acrylic rubber was purified in the same manner as in Example 1 except that the varnish was adjusted using this, and a die bond film was produced.

[Comparative Example 4]
In the “separation purification” of Example 1, “separation purification” was not performed, and the solution immediately after polymerization was dried and dissolved again using cyclohexanone to obtain a star acrylic rubber solution. A die bond film was produced in the same manner as in Example 1 except that a varnish was prepared using the varnish.

[Comparative Example 5]
A die bond film was produced in the same manner as in Example 1 except that the star acrylic rubber was purified by the following reprecipitation purification method in “Separation purification” of Example 1.

"Reprecipitation purification method"
After completion of the reaction, the viscosity of the solution was reduced with acetone and suction filtered. The filtrate was transferred to a 500 ml three-necked flask equipped with a vacuum stirrer. Pure water was added dropwise over 1 hour while stirring at 150 rpm (rotation / min), followed by stirring for 30 minutes. After stirring, vacuum distillation was performed to remove acetone and unreacted monomers. The aqueous solution remaining in the flask was removed with a dropper, and the remaining polymer was washed twice with water and once with methanol, and dissolved again with acetone. After dissolution, pure water was added dropwise again over 1 hour and stirred for 30 minutes. After stirring, vacuum distillation was performed, and the aqueous solution remaining in the flask was removed with a dropper, and then the remaining polymer was washed once with water and methanol. After washing, the polymer was dissolved in cyclohexanone, and the low boiling point solvent was removed by distillation under reduced pressure to obtain a star acrylic rubber solution.

[Evaluation]
The following evaluation was performed about each of the die bond film of the Example obtained from the above and a comparative example.

(1) Measurement of tack force The tack force was evaluated by a probe tack test according to JIS Z0237-1991. Using a tack tester manufactured by Reska Co., Ltd., the peel strength was measured under the conditions of the probe diameter: 5.1 mm, the contact speed: 2 mm / sec, and the peel speed 10 mm / sec. The standard contact conditions were contact load: 0.98 N / cm ² , contact time: 1 sec, and measurement temperature: 40 ° C.

(2) Melt viscosity measurement Two uncured films having a thickness of 40 μm were laminated at 60 ° C. to give a film thickness of 80 μm, punched into a circle having a diameter of 8 mm, and then sandwiched between glass plates / cover glasses. After pressure bonding at 120 ° C., 3 kgf, 3 seconds, the melt viscosity was calculated by using Formula 1. The calculation method is shown in Equation 1. In Equation 1, η is the viscosity, V is the initial volume of the die bond film, t is the pressure bonding time, F is the pressure applied by compression, Z ₀ is the initial film thickness, and Z is the film thickness after pressure bonding.

(3) Die shear strength measurement A die-bonding film of B stage is punched using a 5 mm × 5 mm punching die, laminated to a chip at 40 ° C., and heat is applied to the substrate using a thermocompression tester (manufactured by Hitachi Chemical Technoplant Co., Ltd.). Crimped.
Thereafter, it was cured by heating. Further, after being left on a hot plate at 260 ° C. for 30 seconds, the die shear strength was measured using a universal bond tester (Dage series 4000).
Chip size: 5mm x 5mm x 280μm (thickness)
Substrate: 20 mm × 10 mm × 100 μm (thickness)
Thermocompression bonding conditions: 120 ° C, 0.5kg, 3s
Die shear strength measurement speed: 50 μm / sec

(4) Measurement of weight average molecular weight (GPC)
The synthesized polymer was prepared as a tetrahydrofuran (THF) solution having a concentration of 1% by mass and measured with a GPC (gel permeation chromatography) apparatus manufactured by Tosoh Corporation. The molecular weight was calculated in terms of polystyrene. The eluent was THF, the flow rate was 1 ml / min, and detection was performed by RI (refractometer). A weight average molecular weight was calculated from the obtained peak chart.

(5) PCT extraction The synthesized star-shaped acrylic rubber was dried under reduced pressure, 1 g of star-shaped acrylic rubber and 10 g of ultrapure water were placed in a polytetrafluoroethylene pressure-resistant container and heated in an oven at 120 ° C. for 24 hours. After cooling to room temperature, it was filtered through a 0.2 μm filter to obtain a PCT extracted water sample.

(6) Quantification of anion The bromide ion concentration was quantified under the following conditions using an anion chromatograph (IC-20) manufactured by Nippon Dionex Co., Ltd.
Eluent: 0.1 M sodium carbonate aqueous solution Flow rate: 1 ml / min
Temperature: 30 ° C
Column: AS-9SC manufactured by Nippon Dionex Co., Ltd.

The above evaluation results are shown in Tables 1 to 3.
Table 1 is a table comparing Example 1 and Comparative Examples 1 to 3, and (A) separation of the solution after separation and purification using an organic solvent, (B) a poor polymer solvent, and pure water. It was confirmed sex.

  From Table 1, in Comparative Examples 1 to 3, the aqueous layer and the organic layer are not separated into two layers, and polymer precipitation occurs, whereas in Example 1, the solution after the liquid separation operation is separated into two layers. You can see that In the case of separation purification of a general low molecular weight compound, it is known that separation performance is improved by increasing the amount of an organic solvent and performing a liquid separation operation. However, in the case of a high molecular weight body, as shown in Comparative Examples 1 to 3, it is difficult to improve the separation property by increasing the amount of the organic solvent. This is considered to be due to the fact that the high molecular weight product used in the present invention is likely to precipitate in water. Furthermore, the separation / purification of the present invention is such that the polymerization solution is directly separated and purified, and the hydrophilic polymer good solvent dimethyl sulfoxide as a polymerization solvent is dissolved in the aqueous layer, resulting in the affinity between the aqueous layer and the polymer. Is also considered to be a cause of hindering the two-layer separation. On the other hand, in the liquid separation operation using the separation liquid composition used in the present invention, it can be seen that the two layers are sufficiently separated. The separation liquid composition used in the present invention shows that the separability after the liquid separation operation is improved by appropriately controlling the affinity between the organic layer and the polymer in the aqueous layer.

  Table 2 is a table comparing Example 1 and Comparative Examples 3 to 5, in which the time required for purification by the liquid separation purification method and the reprecipitation production method of the present invention and the PCT extraction for each purified polymer and unpurified polymer were performed. The bromide ion concentration in each PCT extract was quantified and compared by anion chromatography.

  Table 2 shows that the separation and purification of the present invention is low in cost because the process time is short, and the purification efficiency is high. In addition, since the degree of purification is low when the two layers are not separated, it indicates that the liquid separation composition used in the present invention contributes to the cost reduction and high purification efficiency of the polymer.

  Table 3 is a table comparing Example 1 and Comparative Example 5, and compares the physical properties of the die bond film in the case of the liquid separation purification method and the reprecipitation purification method of the present invention.

  From Table 3, this invention shows that the refined polymer is not influenced by the difference in the purification method, and changes are not seen in various properties as a die bond film. Therefore, it is shown that the liquid separation purification method of the present invention can be adopted as a low-cost purification method replacing the reprecipitation purification method.

Claims (11)

  A method for purifying a polymer synthesized by atom transfer radical polymerization, wherein (A) an organic solvent and (B) a poor polymer solvent are added to and mixed with a polymer solution after polymerization, and then pure water is added. In addition, it is separated into two layers, a polymer-containing solution layer and an aqueous solution layer, by stirring and standing, and a polymer purification method for extracting halide ions and transition metal ions remaining in the polymer to the aqueous solution layer side .   A polymer synthesized by atom transfer radical polymerization is a copolymer having a star structure in which at least three polymer chains extend radially, and contains at least 0.1 mol% or more of crosslinkable reactive groups in the molecular chain. The method for purifying a polymer according to claim 1, which is a molecule.   (A) The method for purifying a polymer according to claim 1 or 2, wherein the organic solvent is a water-insoluble organic solvent.   (B) The method for purifying a polymer according to any one of claims 1 to 3, wherein the poor solvent for the polymer is a water-soluble organic solvent.   The mixing ratios of (A) organic solvent, (B) polymer poor solvent and pure water are (A) 50-100 parts by mass, (B) 10-30 parts by mass, and pure water 20-60 parts by mass, respectively. The purification method of the polymer | macromolecule in any one of Claims 1-4.   (B) The polymer poor solvent is an alcohol having 2 to 4 carbon atoms, The polymer purification method according to any one of claims 1 to 5.   The method for purifying a polymer according to any one of claims 1 to 6, wherein the polymer to be purified has a weight average molecular weight of 50,000 to 2,000,000.   The method for purifying a polymer according to any one of claims 1 to 7, wherein the solid content in the aqueous solution layer is 3% by mass or less after stirring and standing.   A purified polymer obtained by the polymer purification method according to claim 1.   The purified polymer according to claim 9 is a copolymer having a star structure in which at least three polymer chains extend radially, and contains at least 0.1 mol% or more of a crosslinkable reactive group in the molecular chain. A purified polymer that is a polymer.   The semiconductor adhesive which uses the refine | purified polymer of Claim 10 as one component of the high molecular weight component of the adhesive for semiconductors which consists of a thermosetting component and a high molecular weight component.