JP3171507B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device using an epoxy resin composition for semiconductor encapsulation which has both low stress properties and moisture resistance reliability and is excellent in moldability.

[0002]

2. Description of the Related Art Semiconductor devices such as transistors and ICs are
From the viewpoint of enabling protection from the external environment and handling of elements, semiconductor devices are sealed with ceramic and plastic packages and the like. In the above ceramic package, the constituent material itself is excellent in moisture resistance, and the stress applied to the semiconductor element can be ignored because of the hollow package. For this reason, highly reliable sealing is possible, but there is a problem in that the constituent material itself is expensive and mass production is poor.

[0003] For these reasons, plastic packages using an epoxy resin composition have recently become mainstream. In sealing with this epoxy resin composition,
Although it is excellent in mass productivity and can be manufactured at low cost, improvement in moisture resistance and low stress is a major problem because it has a moisture permeability of a plastic package and a larger linear expansion coefficient than a semiconductor element.

[0004]

As a method for reducing the stress of a resin for semiconductor encapsulation, a method of reducing the stress by adding and dispersing rubber particles, a method of modifying a resin with silicone oil, and the like have been conventionally performed. However, these methods have the following problems. That is, in the above method of dispersing rubber particles, the rubber particles themselves have high cohesiveness, and thus cannot be uniformly and sufficiently dispersed in the epoxy resin composition. Therefore, there is a limit to the low stress property required as a resin for semiconductor encapsulation.
Further, a problem often arises that the agglomerated rubber particles are deposited not only inside the semiconductor package formed by using the sealing resin but also on the outer surface thereof, resulting in poor appearance. And, the influence of ionic impurities contained in the rubber particles themselves greatly reduces the moisture resistance reliability of the semiconductor element.

In the above method of modifying a resin with silicone oil, although the moisture resistance reliability of the element is improved by the silicone oil, the modified silicone oil oozes onto the surface of the semiconductor package, and the outer surface becomes dirty or oozes out. The marking property of the marking ink decreases due to the oil. Further, there is a problem in molding due to a decrease in strength of the sealing resin.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a semiconductor device which is excellent in all of low stress, moisture resistance reliability and sealability.

[0007]

In order to achieve the above object, a semiconductor device of the present invention encloses a semiconductor element using an epoxy resin composition containing the following components (A) to (D). Take the configuration. (A) Epoxy resin. (B) a phenolic resin. (C) A silicone oil represented by the following general formula (1) .

Embedded image (D) Butadiene rubber particles.

[0008]

In other words, the inventors of the present invention have conducted a series of studies in order to obtain a sealing resin which achieves low stress and high reliability in moisture resistance and which does not hinder the appearance and the printability. Then, the present inventors focused on a method of reducing the stress by adding rubber particles, which has been conventionally performed, and conducted further research mainly on the method of adding rubber particles. As a result, in order not to agglomerate the rubber particles, butadiene in the use of rubber particles, the use of the specific silica <br/> corn oil together, specific silicone oil without the butadiene-based rubber particles agglomerate It has been found that the stress can be reduced without being uniformly dispersed in the inside without depositing aggregates on the outer surface. Moreover, the reliability of moisture resistance is greatly improved by the blending of the specific silicone oil, and the leakage of the specific silicone oil is prevented by the combination of the specific silicone oil and the butadiene rubber particles. The heading reached this invention.

Next, the present invention will be described in detail.

The epoxy resin composition used in the present invention comprises an epoxy resin (A component), a phenol resin (B component), a specific silicone oil (C component), and butadiene rubber particles (D component). It is usually obtained in the form of a powder or a tablet obtained by compressing the powder.

The epoxy resin (component A) is not particularly limited, and various epoxy resins such as cresol novolak type, phenol novolak type, bisphenol type and biphenyl type can be used. Among these epoxy resins, those having a melting point exceeding room temperature and exhibiting a solid or high-viscosity liquid at room temperature are preferably used. For example, as a novolak type epoxy resin, usually, an epoxy equivalent of 150 to 250,
A resin having a softening point of 50 to 130 ° C. is used. As the cresol novolac type epoxy resin, an epoxy equivalent of 180 is used.
Those having a softening point of 60 to 110 ° C are generally used.

The phenol resin (component B) used together with the epoxy resin (component A) acts as a curing agent for the epoxy resin (component A), and is not particularly limited. Phenol novolak and cresol novolak are used. And the like. These phenolic resins have a hydroxyl equivalent of 70-150 and a softening point of 50-1.
It is preferable to use one at 10 ° C.

The mixing ratio of the epoxy resin (component A) and the phenol resin (component B) is such that the hydroxyl equivalent in the phenol resin is 0.5 to 2.0 equivalent per equivalent of epoxy group in the epoxy resin. It is preferable to mix them. It is more preferably 0.8 to 1.2 equivalents.

[0014] The above A is as components and specific silicone oil used in conjunction with B component (C component), silicone oil represented by the Symbol of the general formula (1) is used
You. Higher reliability can be obtained by using this silicone oil.

[0015]

Embedded image

The silicone oil such as the silicone oil represented by the above general formula (1) can be obtained by a conventionally known production method, and its compounding amount is 0.01 to 1.0% by weight of the whole epoxy resin composition. % (Hereinafter abbreviated as “%”), and more preferably 0.01 to
0.3%. That is, if the amount of the silicone oil is less than 0.01%, no sufficient effect of improving the humidity resistance of the semiconductor device is obtained, and if it exceeds 1.0%, the moldability of the epoxy resin composition tends to decrease. Is seen. As the silicone oil represented by the general formula (1), those having a molecular weight of about 300 to 2,000 are used.
A dimethylsiloxane modified with a terminal aminopropyl group of a zero-mer is used. Preferably, a 0 to 20 mer is used. Specifically, the one represented by the following formula (2) is used.
Can be.

[0017]

Embedded image

The butadiene rubber particles (component D) used together with the above components A to C are those obtained by a copolymerization reaction of methyl methacrylate, alkyl acrylate, butadiene, styrene and the like. Preferably, the composition ratio of butadiene is 70% or less, and the composition ratio of methyl methacrylate is 15% or more. The compounding amount of the butadiene-based rubber particles (D component) is preferably set to a ratio of 0.1 to 4.0% of the entire epoxy resin composition, and more preferably 0.1 to 2%. That is, if it is less than 0.1%, a sufficient effect of reducing the stress of the epoxy resin composition cannot be obtained, and if it exceeds 4.0%, the reliability of the semiconductor element due to the ionic impurities contained in the rubber particles is reduced. This is because the rubber particles tend not to be sufficiently and uniformly dispersed.

The epoxy resin composition used in the present invention may further contain, if necessary, a curing accelerator, an inorganic filler, a halogen-based flame retardant such as a brominated epoxy resin, and / or a halogenated flame retardant. Other additives such as a flame retardant aid such as antimony oxide, a pigment such as carbon black, and a surface treatment agent such as a silane coupling agent are appropriately used.

Examples of the curing accelerator include amine type and phosphorus type. Examples of the amine type include imidazoles such as 2-imidazole, triethanolamine,
And tertiary amines such as diazabicycloundecene. Examples of the phosphorus type include triphenylphosphine and the like. These are used alone or in combination. And, the compounding ratio of this curing accelerator is preferably set to a ratio of 0.1 to 1.0% of the whole epoxy resin composition. Further, considering the fluidity of the epoxy resin composition, it is preferably 0.15 to 0.35%.

The inorganic filler is not particularly limited, and includes generally used quartz glass powder, silica powder, alumina, talc and the like. The amount of the inorganic filler is 70 to 8 based on the entire epoxy resin composition.
It is preferable to set the range to 0%.

The epoxy resin composition used in the present invention can be produced, for example, as follows. That is, after the above-mentioned A to E components and other additives are appropriately blended and pre-mixed, the mixture is melted and mixed in a kneading machine such as a mixing roll machine in a heated state, and cooled to room temperature.
It can be manufactured by a series of steps of crushing by known means and tableting as necessary.

In the above production, it is preferable to preliminarily mix a specific silicone oil (component C) and butadiene-based rubber particles (component D). For example, part or all of the butadiene-based rubber particles (D component) and a specific silicone oil (C component) are charged into a mixer such as a ball mill together with mixing balls, rotated for an arbitrary time, and stirred. By mixing, a preliminary mixture of the above-mentioned component C and component D can be obtained. At this time, not only the specific silicone oil (C component) and butadiene-based rubber particles (D component) but also a coupling agent or the like blended in the sealing resin composition may be mixed together. Then, the pre-mixture is sieved to remove aggregates. Then, it is blended and added together with other materials according to the above-mentioned production method.

The sealing of the semiconductor element using such an epoxy resin composition is not particularly limited, and can be performed by a known molding method such as ordinary transfer molding.

The semiconductor device thus obtained has a low stress property because the butadiene rubber particles are uniformly dispersed in the epoxy resin composition used as the sealing resin composition by the specific silicone oil. And the rubber particles have an excellent appearance without forming aggregates of the rubber particles. Further, JP-used in the dispersion of the rubber particles
Due to the effect of certain silicone oils, it has excellent moisture resistance reliability. The use of the butadiene-based rubber particles prevents the specific silicone oil from oozing out, and does not cause a decrease in the printability.

[0026]

As described above, according to the semiconductor device of the present invention, the epoxy resin composition contains butadiene rubber particles (D
The semiconductor element is resin-sealed using a special epoxy resin composition in which the component (C) is uniformly dispersed by a specific silicone oil (C). For this reason, it has a lower stress property than the sealing resin of the resin composition that has been normally compounded and kneaded. Furthermore, it has excellent moisture resistance reliability due to the water repellent effect of a specific silicone oil (component C). Moreover, by using the specific silicone oil (component C) and butadiene-based rubber particles (component D) in combination, the silicone oil component on the package surface is prevented from oozing out and the marking ink is prevented from having a reduced marking property.

Next, examples will be described together with comparative examples.

First, prior to the examples, a premix was prepared by previously mixing silicone oil and butadiene rubber according to the following method.

[Preparation of Premixed Product] 50 parts by weight (hereinafter abbreviated as “parts”) of dimethylsiloxane modified with aminopropyl at both terminals represented by the following structural formula (2)
And 100 parts of butadiene rubber, together with 100 parts of magnetic balls, are placed in a magnetic ball mill grinder for 100 minutes.
Rotated at rpm. This mixture was sieved through a 100-mesh sieve to remove aggregates, thereby preparing a premix.

[0030]

Embedded image

[Preparation of Butadiene Rubber Particles] Only butadiene rubber was used, placed in a magnetic ball mill pulverizer, and rotated at 100 rpm for 120 minutes. And 100
Butadiene rubber particles were prepared by sieving through a mesh.

[0032]

Examples 1-4, Comparative Examples Each raw material shown in Table 1 below was used.
They were blended at the ratios shown in the same table and melt-kneaded for 3 minutes in a roll kneader heated to 90 to 110 ° C. Next, the melt was cooled, pulverized, and further tableted to obtain an epoxy resin composition for semiconductor encapsulation.

[0033]

[Table 1]

The following measurement was carried out on the thus obtained Examples and Comparative Examples. First, transfer molding (molding conditions: 1) was performed using an epoxy resin composition for semiconductor encapsulation in order to measure aggregates of rubber particles.
75mm x 120sec) 3mm x 14mm
Six cured products each having a size of × 20 mm were prepared. Then, the number of particles having a size of 50 μm or more in the cured product was measured by an X-ray photograph. Further, the appearance of the cured product was visually observed to confirm the presence of rubber particle aggregates. The results are shown in Tables 2 and 3 below.

In order to evaluate the moisture resistance reliability of the sealing resin, a semiconductor element (size: 3 mm × 5 mm) on which an aluminum electrode is deposited is used for a 16-pin dual in-line package (abbreviated as “DIP-16”). And wire bonding was performed. Next, the semiconductor device was obtained by resin sealing using the epoxy resin composition for semiconductor sealing. After conducting an initial conduction test of the semiconductor device, the passed product is further exposed to a high-temperature and high-humidity condition of 125 ° C./85% RH to apply a bias voltage of 30 V [Pressure cooker bias test (PCBT test)]. ], And the resistance change rate was measured at regular time intervals. When the rate of change became twice or more of the initial value, a conduction failure was determined, and the time required for half of the total test pieces to be defective was determined. The results are shown in Tables 2 and 3 below.

Further, in order to measure the stress property of the sealing resin, a piezo element (size: 3 mm × 5 mm) is connected to a DIP.
After assembling into a frame for −16 and performing wire bonding, resin sealing was performed using an epoxy resin composition for semiconductor sealing to obtain a semiconductor device. Then, the stress applied to the piezo element was measured by a change in the resistance of the element. The results are shown in Tables 2 and 3 below.

Test pieces for measuring the coefficient of thermal expansion and the elastic modulus of the cured resin were prepared, and their physical properties were measured using a thermomechanical analyzer and a bending tester, respectively. Further, the index of the stress of the cured resin was determined from the product of the coefficient of thermal expansion and the elastic modulus. The results are shown in Tables 2 and 3 below.

Then, each package was marked with a normal marking ink, and the sealability was measured and evaluated. The results are shown in Tables 2 and 3 below.

[0039]

[Table 2]

[0040]

[Table 3]

From the results shown in Tables 2 and 3, no unevenness was formed on the surface of the example product. Then, in the moisture resistance reliability test, the average life time by the PCBT test was shorter for the comparative example product. Furthermore, the result of the measurement of the stress property by the piezo element shows that the comparative example product has a high stress. In contrast, it can be seen that the example product has low stress in both the major axis direction and the minor axis direction of the package. Further, the product of the example had lower values in all of the thermal expansion coefficient, the flexural modulus and the stress index than the product of the comparative example. In the sealability, the comparative example was poor due to oozing out of the silicone oil, whereas the comparative example was all good.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-186724 (JP, A) JP-A-2-29421 (JP, A) JP-A-2-32118 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) H01L 23/29 C08G 59/62 C08L 63/00 H01L 23/31

Claims (6)

(57) [Claims] 1. A semiconductor device comprising a semiconductor element encapsulated with an epoxy resin composition containing the following components (A) to (D). (A) Epoxy resin. (B) a phenolic resin. (C) A silicone oil represented by the following general formula (1) . Embedded image (D) Butadiene rubber particles. 2. The semiconductor device according to claim 1, wherein the butadiene rubber particles as the component (D) are previously dispersed in the silicone oil as the component (C). 3. The silicone oil as the component (C),
Claims are silicone oils represented by the following formula (2):
Item 3. The semiconductor device according to item 1 or 2. Embedded image 4. An epoxy resin composition for semiconductor encapsulation comprising the following components (A) to (D). (A) Epoxy resin. (B) a phenolic resin. (C) A silicone oil represented by the following general formula (1) . Embedded image (D) Butadiene rubber particles. 5. The epoxy resin composition for semiconductor encapsulation according to claim 4, wherein the butadiene rubber particles as the component (D) are previously dispersed in the silicone oil as the component (C). 6. The silicone oil as the component (C),
Claims are silicone oils represented by the following formula (2):
Item 6. The epoxy resin composition for semiconductor encapsulation according to item 4 or 5 . Embedded image