JP2002284889A - Manufacturing method of resin paste for semiconductor, resin paste for semiconductor and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin paste for a semiconductor excellent in reliability enough not to deteriorate bonding strength when heated and not to cause peeling of a resin paste layer for a semiconductor in a soldering crack resistance test after a moisture-absorbing treatment, and its manufacturing method. SOLUTION: The manufacturing method of the resin paste for a semiconductor comprising a thermosetting resin (A), a filler (B) and a silane coupling agent (C) comprises mixing a portion or the whole of (B) with the thermosetting resin component and treating the thus-obtained mixture in a wet bead mill or a high-speed rotary homogenizer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a resin paste for a semiconductor for bonding a semiconductor element such as an IC or an LSI to a metal frame, an organic substrate or the like, and to a resin paste for a semiconductor produced by the method. is there.

[0002]

2. Description of the Related Art In recent years, when a semiconductor element such as an IC is mounted on a lead frame, an organic substrate or the like, a resin paste for a semiconductor has been used in order to prevent cracks and warpage of the semiconductor element. .

[0003] A resin paste for a semiconductor is usually composed of components such as a thermosetting resin and an inorganic filler. In order to uniformly mix and knead these components, as a production method, a predetermined amount of weighed component raw materials is used. A process of manufacturing using a kneader such as a three-roll mill or a universal stirrer is employed. However, these kneaders cannot sufficiently disperse the filler in the thermosetting resin, the viscosity of the produced resin paste for semiconductors is high, threading occurs at the time of dispensing, and the workability deteriorates, or the resin is left at room temperature. In this case, there is a problem that the viscosity and the thixotropy decrease, and the resin paste for a semiconductor drips from the tip of the needle.

On the other hand, in response to the trend toward smaller and lighter electronic devices and higher functionality, semiconductor packages have become smaller and thinner.
As the pitch becomes increasingly narrow, resin pastes for semiconductors are required to improve solder cracking resistance and moisture resistance after moisture absorption, which is related to the reliability of semiconductor packages after encapsulation with epoxy resin molding materials. Have been. The conventional manufacturing method does not uniformly disperse and knead, so that the adhesion between the lead frame or the semiconductor chip and the resin paste for the semiconductor is reduced, and the reliability of the package is not improved as expected. To solve this problem, there is a method in which all or a part of the filler is mixed with a thermosetting resin, and the mixture is treated with a wet bead mill.

[0005] Thereafter, due to environmental problems, Pb has not been used for soldering when mounting a semiconductor package on a substrate. When a solder that does not use Pb is used, the melting point of the solder increases, and the temperature at the time of solder mounting becomes lower than the conventional temperature.
Since the temperature rises from 40 ° C. to about 260 ° C., the solder crack resistance of the semiconductor package after the moisture absorption treatment becomes severe, and further improvement in the adhesive strength and the solder crack resistance of the semiconductor resin paste is required. None of the resin pastes for semiconductors manufactured using a conventional wet bead mill processing method or the like satisfy the required solder crack resistance.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly reliable semiconductor which does not lower the adhesive strength during heating and does not cause peeling of the resin paste layer for a semiconductor in a solder crack resistance test after a moisture absorption treatment. To provide a resin paste for use and a method for producing the same.

[0007]

The present invention relates to (A) a thermosetting resin, (B) a filler and (C) a silane coupling agent represented by the general formula (1) or a silane coupling agent represented by the general formula (1). In a resin paste for a semiconductor comprising a hydrolyzate obtained by hydrolyzing all or a part of an alkoxy group contained in a ring agent, a part or all of the filler is mixed with the thermosetting resin component, and this mixture is mixed. Is processed by a wet bead mill or a high-speed rotary homogenizer to produce a resin paste for semiconductors.

Embedded image (R ₁ is a monovalent group having an amino group or a ureido group, R ₂
Is an alkoxy group having 1 to 10 carbon atoms, and R ₃ is an alkoxy group having 1 to 1 carbon atoms.
An alkyl group of 0. m is an integer of 1 to 10, and n is an integer of 1 to 3. As a more preferred embodiment, after the surface of the filler (B) is previously treated with the component (C), part or all of the component (B) is mixed with the thermosetting resin component, and the mixture is subjected to wet bead milling or high-speed rotation. This is a method for producing a resin paste for a semiconductor, which is produced by treating with a homogenizer. Further, the present invention is a semiconductor device manufactured using the above-mentioned resin paste for a semiconductor.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has been studied for the production of a resin paste for semiconductors containing fillers. As a result, the viscosity, the change in viscosity, and the reduction in adhesion are strongly related to the aggregation of fine particles having a small filler particle size. It has been found that a resin paste for a semiconductor having excellent adhesion can be obtained by uniformly dispersing the filler in the production method.

The thermosetting resin (A) used in the present invention is a general thermosetting resin comprising a resin, a curing agent, a curing accelerator and the like, and is not particularly limited, but is a material for forming a paste. Therefore, it is desirable to be liquid at room temperature.

[0010] The liquid resin used in the present invention includes:
For example, a liquid cyanate resin, a liquid epoxy resin such as bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol E epoxy resin,
Examples include alicyclic epoxy resins, aliphatic epoxy resins, glycidylamine type liquid epoxy resins, various radically polymerizable acrylic resins, and triaryl isocyanurates having an aryl group.

Examples of the curing catalyst for the cyanate resin include metal complexes such as copper acetylacetonate and zinc acetylacetonate. Examples of epoxy resin curing agents include aliphatic amines, aromatic amines, dicyandiamide, dicarboxylic dihydrazide compounds, and phenol resins. Examples of the dihydrazide compound include carboxylic acid dihydrazides such as adipic dihydrazide, dodecanoic dihydrazide, isophthalic dihydrazide, and P-oxybenzoic dihydrazide.

As the curing accelerator / curing agent, there are various imidazole compounds, examples of which are 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole,
Phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxy methyl imidazole, 2-C ₁₁ H ₂₃ - adds a generic imidazole or triazine and isocyanuric acid such as imidazole, storage stability 2,4-diamino-6- {2-methylimidazole- (1)}-ethyl-S-triazine,
There is also an isocyanate adduct thereof, and any of these can be used in combination with one type or a plurality of types.

In the present invention, it is sufficiently possible to mix thermosetting resin components which are solid at room temperature to such an extent that the properties do not deteriorate. For example, bisphenol A, bisphenol F, phenol novolak, aliphatic epoxy such as polyglycidyl ether, butanediol diglycidyl ether, neopentyl glycol diglycidyl ether and the like obtained by reacting cresol novolacs with epichlorohydrin, and complex such as diglycidyl hydantoin. Cyclic epoxy, vinylcyclohexene dioxide,
There are alicyclic epoxies such as dicyclopentadiene dioxide and alicyclic diepoxy-adipate, which can be used in combination with one or more of these.

The filler (B) used in the present invention includes an inorganic filler and an organic filler. Examples of the inorganic filler include metal powder such as gold powder, silver powder, copper powder, and aluminum powder, fused silica, crystalline silica, silicon nitride, alumina, aluminum nitride, and talc. Examples of the organic filler include a silicone resin, a fluorine resin such as polytetrafluoroethylene, an acrylic resin such as polymethyl methacrylate, and a crosslinked product of benzoguanamine or melamine with formaldehyde. Among them, the metal powder is mainly used for imparting electrical conductivity or thermal conductivity.

The filler used has a content of ionic impurities such as halogen ions and alkali metal ions of 10 p.
pm or less. The shape may be a flake, scale, resin, or sphere. The particle size used varies depending on the required viscosity of the paste, but usually the average particle size is preferably 0.3 to 20 μm, and the maximum particle size is preferably about 50 μm. When the average particle size is less than 0.3 μm, the viscosity increases, and when the average particle size exceeds 20 μm, bleeding may occur because the resin component flows out during coating or curing.
If the maximum particle size exceeds 50 μm, the outlet of the needle may be blocked when applying the paste with a dispenser, and it may not be possible to use the paste continuously for a long time. In addition, a mixture of a relatively coarse filler and a fine filler may be used, and various types and shapes may be appropriately mixed.

[0016] Fillers other than the present invention may be added to impart the required properties. For example, the particle size is 1
There are nano-scale fillers of about 100 nm and organic and inorganic composite fillers such as silica and acrylic composites.

The silane coupling agent of the general formula (1) used in the present invention has an amino group or a ureide group. By containing these, the reactivity with the resin is enhanced, and at the same time, fillers and various base materials are used. The adhesive strength can be improved by reacting with hydroxyl groups on the surface. In the silane coupling agent represented by the general formula (1), R ₂ represents an alkoxy group having 1 to 10 carbon atoms, and R ₃ represents a 1 carbon atom.
Is an alkyl group of 10 to 10, and n is an integer of 1 to 3, but n is most preferably 3 because the alkoxy group improves the adhesion to the inorganic filler and various base materials. Further, by adjusting the carbon number of the alkoxy group, the reactivity between the silane coupling agent and the resin or the inorganic filler can be adjusted.

Specific examples of the silane coupling agent represented by the general formula (1) are shown below, but are not limited thereto.

Embedded image

Further, a hydrolyzate obtained by previously hydrolyzing all or a part of the alkoxy group of the silane coupling agent may be used. In this case, since the alkoxy group has been hydrolyzed in advance, a hydrogen bond or a covalent bond can easily be formed with the filler or the hydroxyl group on the surface of various base materials, and the adhesive strength can be improved.

The silane coupling agent, which is present on the filler surface, is considered to be effective in chemically bonding the filler and the organic component in the thermosetting resin and improving the interfacial adhesion. As described above, in order to improve the interfacial adhesion between the filler and the organic component, it is necessary that the silane coupling agent be present in the filler.
By treating the filler surface with a hydrolyzate obtained by hydrolyzing all or a part of the alkoxy group contained in the silane coupling agent or each of the silane coupling agents shown in It is effective for improving strength. As a method of treating the filler surface with a silane coupling agent or a hydrolyzate, a solution of a silane coupling agent or its alcohol or the like, a hydrolyzate is sprayed on the filler being stirred, and after further stirring,
The surface-treated filler can be obtained by leaving at room temperature or heating. In addition to the treatment on the filler surface, a method of previously heating and mixing a silane coupling agent with an integral blend or a resin may be used in combination.

The resin paste for a semiconductor according to the present invention may contain a silane coupling agent other than the general formula (1), a titanate coupling agent, a pigment, a dye, a defoaming agent as long as the characteristics according to the intended use are not impaired. Additives such as agents, surfactants, and solvents can be used.

In the present invention, a component having a particle size smaller than the weight average particle size in the particle size distribution of the entire filler is defined as a fine particle component. The present invention achieves compatibility between workability such as viscosity and thixotropy and adhesion by selectively treating a fine particle component having a large cohesive force with a wet bead mill or a high-speed rotating homogenizer.

In order to uniformly disperse and mix the fine particles,
In the conventional method for producing a resin paste for a semiconductor, a large shearing energy capable of destroying the aggregation of the fine particles of the filler cannot be applied, so that the dispersion and mixing did not proceed even if the kneading was performed for a long time. In particular, in the case of the surface-treated filler, the filler easily aggregates, but the effect of dispersing the aggregated filler is small. On the other hand, in the present invention, it is possible to apply a large shear energy capable of breaking the aggregation of the filler fine particle component, and to uniformly mix the resin, the viscosity and thixotropic properties of the kneaded semiconductor resin paste are stabilized. Also, there is no needle clogging when applying the paste with a dispenser, and the kneading process can be performed in a short time. In particular, the average particle size of the filler is 5μ.
This effect is large when a fine filler of m or less is used for the resin paste for semiconductors.

The wet bead mill used in the present invention is not particularly limited as long as it has a rotor for creating a shear field and beads moving in the shear field in a container for processing a resin containing a filler. Equipped with a heating or cooling mechanism in the container or the piping section attached to it, a pump mechanism that can repeatedly process the resin containing the filler, and a separator mechanism that prevents the beads from flowing out when the resin is discharged. It is preferable to use the continuous type provided. The beads to be used are not limited, but depending on the material and fraction of the filler, zirconia having a diameter of 0.2 to 1.0 mm, alumina, glass, and iron can be used. It is preferable to fill 20 to 90% by volume. In the case of a continuous wet bead mill equipped with a separator mechanism, the viscosity of the resin containing the filler is adjusted to 100 Pa · s by adjusting the processing temperature, the compounding amount of the filler, and the processing flow rate in order to smoothly perform the repetitive processing.
It is necessary to:

The high-speed rotation type homogenizer is not particularly limited as long as it has a rotor and a screen having slits for rotating the liquid by rotating at a high speed. Alternatively, a device provided with a cooling mechanism is preferable. The material and shape of the rotor and screen used are not particularly limited,
It is desirable to change according to the material and fraction of the filler and the viscosity of the resin containing the filler. In order to smoothly process the high-speed rotary homogenizer, it is necessary to adjust the processing temperature and the amount of the filler to adjust the viscosity of the resin containing the filler to 100 Pa · s or less. Here, the high-speed rotation type homogenizer generally means one having a rotation speed of 3000 rpm or more.

All of the fillers may be treated by a wet bead mill or a high-speed rotating homogenizer. However, when the viscosity of the resin containing the filler is high or when there are many fine particles,
It is also effective to treat a part of the filler with a wet bead mill or a high-speed rotary homogenizer. When a part of the filler is treated by a wet bead mill or a high-speed rotating homogenizer, it is desirable to selectively treat the fine particle component. Generally, if at least 30% of the filler is treated with a wet bead mill or a high-speed rotating homogenizer, the effect of the present invention can be recognized. However, in the case of a filler having an average particle size of 0.1 μm or less, the effect can be recognized even at about 3%. This is because when a filler uniformly dispersed in a resin by a wet bead mill or a high-speed rotating homogenizer is mixed with a resin of a normal kneading method, the uniformly dispersed filler is effective because it enters between non-uniform fillers. Conceivable. In addition, fillers having a smaller particle size are more likely to be aggregated and cannot be dispersed by a usual kneading method. The remaining filler is mixed by a mixing method such as an ordinary three roll or universal stirrer. A known method can be used as a method for manufacturing a semiconductor device.

[0027]

The present invention will be specifically described below with reference to examples and comparative examples. <Examples 1 to 11> Examples 1 to 11 and the preliminary mixture were prepared by mixing each component having the composition shown in Table 1 and a filler, and kneading the mixture with a wet bead mill and a high-speed rotating homogenizer to obtain a resin paste. The wet-type bead mill is a wet-type bead mill (rotor-rotation speed: 2500) in which a processing chamber (volume: 500 cm ³ ) is filled with 30% by volume of zirconia beads having a diameter of 0.8 mm.
(rpm, temperature 20 ° C., flow rate 1500 cm ³ / min, separator interval 0.3 mm) for 10 minutes. The high-speed rotating homogenizer is a high-speed rotating homogenizer having a slit width of 1.0 mm and a clearance between the rotor and the screen of 0.2 mm (rotor rotation speed 15,000 rpm,
(Temperature: 20 ° C.) for 10 minutes. In Example 11, silica was added to the premix subjected to the bead mill treatment and kneaded with a three-roll mill. After defoaming the resin paste at 2 mmHg for 30 minutes in a vacuum chamber, various performances were evaluated by the following methods. Table 1 shows the evaluation results of the examples.

<Raw materials used> Liquid epoxy resin: bisphenol F type epoxy resin (viscosity 4.0 Pa · s / 25 ° C., epoxy equivalent 170)
(Hereinafter referred to as BPFEP) Phenol resin: phenol novolak resin (softening point 110 ° C., hydroxyl equivalent 105) (hereinafter referred to as PN) Dicyandiamide (hereinafter referred to as DDA) 2-Phenyl-4-methyl-5-hydroxymethyl Imidazole (hereinafter referred to as 2P4MHZ) Cyanate L-10

Embedded image

Cobalt naphthenate Urethane acrylate 1,1-bis (t-hexylperoxy) -3,3
5-trimethylcyclohexane (hereinafter referred to as Perhexa 3
M) • γ-aminopropyltriethoxysilane • γ-ureidopropyltriethoxysilane • Production example of hydrolyzate A γ-aminopropyltriethoxysilane and pure water are mixed with 80:
The mixture was mixed at a ratio of 20 (weight ratio), and the mixture was sufficiently stirred and mixed until the mixture was not separated into two layers to obtain a hydrolyzate A.・ Inorganic filler Silver powder: Flake silver powder having an average particle diameter of 3 μm and a maximum particle diameter of 50 μm Silica: silica powder having an average particle diameter of 1.5 μm and a maximum particle diameter of 20 μm ・ Production example of surface-treated silica A Average particle diameter of 1.5 μm While stirring 100 parts by weight of a silica powder having a maximum particle size of 20 μm with a mixer, 0.5 parts by weight of γ-aminopropyltriethoxysilane was added dropwise. After continuing stirring for 15 minutes as it is, it was left at room temperature for 8 hours to obtain surface-treated silica A.

<Evaluation method> Viscosity: 25 ° C. using an E-type viscometer (3 ° cone);
The value at 5 rpm was measured and defined as the viscosity. Pot life: The number of days until the viscosity when the resin paste for a semiconductor was allowed to stand in a constant temperature bath at 25 ° C. increased to 1.5 times or more the initial viscosity was measured.・ Thixotropic ratio change: 2 using E-type viscometer (3 ° cone)
Thixo ratio at 5 ° C. (viscosity at 0.5 rpm / 2.5 rpm
m) and the thixo ratio when the semiconductor resin paste was left in a thermostat at 25 ° C. for 72 hr, and the thixo ratio change was calculated as (thixo ratio after 72 hr / initial thixo ratio). Adhesive strength: A silicon chip of 5 × 5 mm was mounted on a copper frame using a resin paste for a semiconductor, and cured at 200 ° C. for 60 minutes using an oven. After curing, the die shear strength at the time of heating at 260 ° C. was measured using a mount strength measuring device. -Needle clogging frequency: A needle with an inner diameter of 0.4 mm was attached to the tip of a 5 ml syringe containing a resin paste for semiconductors, and the needle was clogged 1000 times with a dispenser at a discharge pressure of 0.1 Pa and a discharge time of 0.1 second. Was confirmed how many times occurs. -Solder resistance (peeling rate): Silicon chip (size 9.0
mm × 9.0 mm) was mounted on a lead frame (made of copper) using a resin paste for semiconductors, and cured at 200 ° C. for 60 minutes in a nitrogen atmosphere using an oven. This lead frame is made of an 80-pin QFP (package size is 14 × 20 mm, thickness is 2.times.) Using an epoxy resin sealing material.
0 mm) at a mold temperature of 175 ° C., an injection pressure of 7.5 MPa,
Transfer molding with curing time 60 seconds, 175 ° C,
Postcured in 8 hours. 85 ° C,
Leave for 168 hours in an environment with a relative humidity of 85%.
It was immersed in a solder bath at 60 ° C. for 10 seconds. Measure the total peel area inside the package using a transmission type ultrasonic flaw detector, and measure the peel area between the chip and epoxy resin sealing material and the lead frame and epoxy using a reflection type ultrasonic flaw detector. The total value of the peeled area from the resin sealing material was measured.
(Peeling area of die attach layer) = [(total value of peeling area in transmission) − (total value of peeling area in reflection)]
The peeling rate of the resin paste for semiconductor is calculated as follows: (peeling rate) = [(peeling area of die attach layer) / (chip area) × 100]
The average value of the five packages was determined and expressed in%.

Comparative Examples 1 to 10 Resin pastes for semiconductors were obtained in the same manner as in the examples according to the formulations in Table 2, and evaluated in the same manner as in the examples. Table 2 shows the results. The coupling agents used in the comparative examples are shown below. • γ-glycidoxypropyltrimethoxysilane • Production example of hydrolyzate B γ-glycidoxypropyltrimethoxysilane and pure water are mixed at a ratio of 80:20 (weight ratio), and this mixture is separated into two layers. The mixture was sufficiently stirred and mixed until it disappeared to obtain a hydrolyzate B. Production example of surface-treated silica B 0.5 parts by weight of γ-glycidoxypropyltrimethoxysilane was dropped while stirring 100 parts by weight of a silica powder having an average particle diameter of 1.5 μm and a maximum particle diameter of 20 μm with a mixer. Added. After continuing stirring for 15 minutes, the mixture was stirred at room temperature for 8 minutes.
It was left for a while to obtain surface-treated silica B.

The evaluation results are shown in Tables 1 and 2.

[Table 1]

[0033]

[Table 2]

[0034]

According to the present invention, the dispersion of the filler in the thermosetting resin is good, and the adhesive strength under heat is not reduced.
The present invention can provide a highly reliable resin paste for a semiconductor that does not cause peeling of the resin paste layer for a semiconductor in a solder crack resistance test after a moisture absorption process, and a method for producing the same.

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Claims (4)

[Claims] 1. A silane coupling agent represented by the following general formula (1): (A) a thermosetting resin, (B) a filler, and (C) a silane coupling agent represented by the general formula (1). In a resin paste for a semiconductor consisting of a hydrolyzate obtained by hydrolyzing all or a part of the filler, a part or all of the filler is mixed with the thermosetting resin component,
A method for producing a resin paste for semiconductors, wherein the mixture is processed by a wet bead mill or a high-speed rotary homogenizer. Embedded image (R ₁ is a monovalent group having an amino group or a ureido group, R ₂
Is an alkoxy group having 1 to 10 carbon atoms, and R ₃ is an alkoxy group having 1 to 1 carbon atoms.
An alkyl group of 0. m is an integer of 1 to 10, and n is an integer of 1 to 3. ) 2. After preliminarily treating the surface of the filler (B) with the component (C), a part or all of the component (B) is mixed with the thermosetting resin component, and the mixture is wet-milled or a high-speed rotary homogenizer. The method for producing a resin paste for a semiconductor according to claim 1, wherein the resin paste is produced by treating the resin paste. 3. A resin paste for a semiconductor manufactured by using the method for manufacturing a resin paste for a semiconductor according to claim 1 or 2. 4. A semiconductor device manufactured using the resin paste for a semiconductor according to claim 3.