JP2003155327A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition for sealing semiconductors in which the separating property between gold plating on a printed circuit board of a runner and a gate part and an epoxy resin composition is compatible with adhesion between a bonding pad (to which gold plating is applied) and the epoxy resin composition when a stress occurs in the interior of sealing and to provide an area mounted type semiconductor device using the resin composition. SOLUTION: This epoxy resin composition comprises (A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator and (D) inorganic filler. In the epoxy resin, particles having <=1 μm diameter are contained in an amount of 10-30 wt.% in total inorganic filler and flexural modulus under the environment at 260 deg.C of the epoxy resin composition is 600 to 1,000 N/mm<2> and heat shrinkage factor is <0.25% at 30-175 deg.C and <0.20%. at 175-260 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called area mounting type semiconductor device in which a semiconductor element is mounted on one surface of a printed wiring board or a metal lead frame, and substantially only one surface on the mounting surface side is resin-sealed. The present invention relates to a suitable epoxy resin composition for semiconductor encapsulation and a semiconductor device using the same.

[0002]

2. Description of the Related Art In recent years, the amount of information processing has become enormous in electronic devices equipped with LSIs, and high-speed operation is strongly required. Along with this, the number of required terminals of LSI is rapidly increasing. To arrange a large number of external terminals of a semiconductor device at a wide pitch, it is effective to use the bottom surface of the semiconductor device.
An area array type surface mount semiconductor device in which solder bumps are arranged in a matrix on this portion is a BGA (Ball G).
rid Array). On the other hand, mobile devices are becoming smaller, thinner, and lighter, which requires semiconductor elements to have lower power and higher functionality, and semiconductor devices in which these semiconductor elements are encapsulated are also smaller. However, thinning and lightening are required, and as a result, C has been put to practical use.
SP (Chip Size Package).
This is basically a reduction in the terminal pitch of the BGA within a range where low-cost consumer mounting is possible, and the size of the semiconductor device is reduced to almost the semiconductor element size. However, semiconductor devices are currently undergoing a major revolution, and CSP structures are diversifying in pursuit of cost performance. At the same time, the demands for epoxy resin compositions for semiconductor encapsulation are increasing.

The structure of these area mounting type semiconductor devices is as follows.
Only the semiconductor element mounting surface of the substrate is sealed with the epoxy resin composition, and the solder ball forming surface side is not sealed. In rare cases, a metal substrate such as a lead frame may have an encapsulating resin layer of about several tens of μm even on the solder ball forming surface, but on the semiconductor element mounting surface, encapsulation of about several hundred μm to several mm. Since the resin layer is formed, it is substantially one-sided sealed.

In the case of a printed wiring board, in order to increase the adhesion of the board to the epoxy resin composition, it is common to perform a surface treatment with plasma or the like before encapsulation. However, the adhesion to the runner and the gate, which must be separated during automatic operation during production, will also be good, so this part is designed to be gold-plated for easy separation. Good separation from gold plating is very important for improving productivity, but as a trade-off, it promotes peeling from the bonding pad (gold-plated) inside the seal. There is a problem that it ends up. In the structure of the conventional semiconductor device, the stress generated in the bonding pad portion was not so large, and the conduction failure due to the adhesion with the epoxy resin composition was not reached. However, in recent years, as the demand for smaller, thinner, and lighter semiconductor devices has increased, and the semiconductor element area has increased with respect to the semiconductor device area, the distance between the bonding pad and the semiconductor element has become closer, and the occurrence of the bonding pad The stress is increased, and a conduction failure due to the adhesion with the epoxy resin composition is likely to occur. Conventional resins cannot deal with such semiconductor devices.

[0005]

SUMMARY OF THE INVENTION The present invention is directed to a runner,
A semiconductor that achieves both the separability between the gold plating on the printed wiring board of the gate part and the epoxy resin composition, and the adhesion between the bonding pad (which has been gold plated) and the epoxy resin composition when stress occurs inside the encapsulation. An epoxy resin composition for encapsulation and an area-mounted semiconductor device using the same are provided.

[0006]

The present invention provides [1] (A)
In an epoxy resin composition containing an epoxy resin, (B) phenol resin, (C) curing accelerator, and (D) inorganic filler as main components, 1 μm or less of particles of 1 μm or less is contained in all inorganic fillers.
The flexural modulus of the cured product of the epoxy resin composition in an environment of 260 ° C. is 600 to 1
000 N / mm ² , the heat shrinkage rate is less than 0.25% at 30 to 175 ° C., and the thermal shrinkage ratio at 175 to 260 ° C. is 0.
Epoxy resin composition characterized by being less than 20%, at least part of [2] (A) epoxy resin represented by formula (1), and / or (B) at least part of phenol resin The epoxy resin composition according to the item [1], wherein is a phenol resin represented by the formula (2):

[Chemical 3] (In the formula, R ₁ and R ₂ are the same or different groups selected from alkyl groups having 1 to 4 carbon atoms. A is an integer of 0 to 3, b is an integer of 0 to 4, and n is an average value. And n is a positive number of 1 to 10.)

[Chemical 4] (In the formula, R ₃ and R ₄ are the same or different groups selected from alkyl groups having 1 to 4 carbon atoms. C is an integer of 0 to 3, d is an integer of 0 to 4, and n is an average value. And n is a positive number of 1 to 10.) [3] The epoxy resin represented by the formula (1) in the (A) epoxy resin and the (B) phenol resin, the formula (2).
[4] The epoxy resin composition according to the item [1], wherein the total amount of the phenol resin represented by the formula is 25 to 100% by weight.
A semiconductor element is mounted on one surface of a substrate, and substantially only one surface on the substrate surface side on which the semiconductor element is mounted is referred to in the item [1].
A semiconductor device sealed with the epoxy resin composition according to any one of the items [3].

[0007]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called area mounting type semiconductor device in which a semiconductor element is mounted on one surface of a printed wiring board or a metal lead frame, and substantially only one surface on the mounting surface side is resin-sealed. The present invention relates to a suitable epoxy resin composition for semiconductor encapsulation and a semiconductor device using the same.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is achieved by controlling the particle size of an inorganic filler in an epoxy resin composition, the flexural modulus at 260 ° C., and the heat shrinkage at 30 to 175 ° C. and 175 to 260 ° C. , The runner and the separation of the epoxy resin composition from the gold plating on the printed wiring board of the gate part, and the adhesion between the bonding pad (which is gold plated) and the epoxy resin composition when stress occurs inside the encapsulation. It was found that they can be compatible.

The epoxy resin used in the present invention is not particularly limited, but for example, biphenyl type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, stilbene type epoxy resin, phenol novolac type epoxy resin, ortho resin. Examples thereof include cresol novolac type epoxy resin, naphthol novolac type epoxy resin, triphenol methane type epoxy resin, dicyclopentadiene modified phenol type epoxy resin, terpene modified phenol type epoxy resin and hydroquinone type epoxy resin. Of these, one type may be used alone or two or more types may be used in combination as long as the characteristics described in claim 1 are satisfied, but it is preferable to add the epoxy resin represented by the formula (1). .

As the phenol resin used in the present invention,
Although not particularly limited, examples thereof include phenol novolac resin, cresol novolac resin, dicyclopentadiene modified phenol resin, phenol aralkyl resin, terpene modified phenol resin, and triphenolmethane type resin. If one of these is used alone within the range satisfying the characteristics described in claim 1, 2
Although more than one kind may be used in combination, it is preferable to blend the phenol resin represented by the formula (2).

The curing accelerator used in the present invention is not particularly limited as long as it accelerates the reaction between the epoxy group and the phenolic hydroxyl group. For example, 1,8-diazabicyclo (5,4,0) undecene-7, Examples thereof include triphenylphosphine, benzyldimethylamine, 2-methylimidazole and the like, and these may be used alone or in combination.

The type of the inorganic filler used in the present invention is not particularly limited, and those generally used for sealing materials can be used. For example, fused crushed silica,
Examples thereof include fused spherical silica, crystalline silica, secondary agglomerated silica, alumina, titanium white, and aluminum hydroxide, and fused spherical silica is particularly preferable. The shape of the spherical silica particles is preferably infinitely spherical for improving the fluidity, and the particle size distribution is broad.

As the particle size distribution of the inorganic filler in the present invention, 10 to 30% by weight of particles having a size of 1 μm or less is blended so that the separation of the gold plating on the runner and the gate printed circuit board from the epoxy resin composition is good. This is because If the particle size of 1 μm or less is less than 10% by weight, sufficient separability cannot be obtained, and if it exceeds 30% by weight, the fluidity is impaired. The particle size distribution of the inorganic filler here is JI
S M8100 powder lump mixture-inorganic filler is collected according to the sampling method general rule, JIS R 1622-1
In accordance with the general rules for sample preparation for measuring the particle size distribution of fine ceramic raw materials, JIS R 1629-1997 is used for measuring the particle size distribution of fine ceramic raw materials by a laser diffraction / scattering method. Similarly, using a laser diffraction particle size distribution analyzer SALD-7000 (laser wavelength: 405 nm) manufactured by Shimadzu Corporation, water is used as a solvent, and the refractive index of the inorganic filler is 1.45 in the real part and imaginary part. It is a value measured under the condition of 0.00.

Further, in the present invention, the cured product of the epoxy resin composition has a flexural modulus of 6 at 260 ° C.
It is from 100 to 1000 N / mm ² . 1000
The reason why it is set to N / mm ² or less is that it is exposed to a heating step of 200 ° C. or more when mounting a solder ball on an area mounting type semiconductor device and when performing solder joining on a circuit board mounting the same. However, this is to relieve the stress generated at this time. Flexural modulus 1000 N / mm ²
When it exceeds, the stress relaxation when exposed to the heating step is not sufficiently performed, so that peeling of the interface between the bonding pad and the epoxy resin composition is likely to occur. Also,
The reason why the flexural modulus is 600 N / mm ² or more is
When it is less than 600 N / mm ² , the thermal contraction rate becomes large and the amount of moisture absorption becomes large, so that the generated stress becomes large, and peeling between the bonding pad and the epoxy resin composition interface easily occurs, and This is because the solder crack resistance is deteriorated.

In the present invention, the cured product of the epoxy resin composition has a heat shrinkage of 0.2 at 30 to 175 ° C.
It is less than 5% and less than 0.20% at 175 to 260 ° C. The reason why the heat shrinkage rate is low in recent years is that the demand for smaller, thinner, and lighter semiconductor devices has increased, the semiconductor element area has increased with respect to the semiconductor device area, and the distance between the bonding pad and the semiconductor element has decreased. Then, the area where large stress is generated between the semiconductor element outer periphery and the epoxy resin composition and the area of the bonding pad are overlapped in position due to the difference in the coefficient of thermal expansion. This is because the suppression suppresses the residual stress generated between the outer periphery of the semiconductor element and the epoxy resin composition, and suppresses the decrease in adhesion between the epoxy resin composition and the bonding pad interface. 30-1
Heat shrinkage at 75 ° C is 0.25% or more, 175-2
When the heat shrinkage ratio at 60 ° C is 0.20% or more, the adhesion is significantly reduced due to residual stress, and when exposed to a heating process at 200 ° C or more, peeling occurs between the bonding pad and the epoxy resin composition interface. It becomes easier to do.

The flexural modulus of the cured product of the epoxy resin composition can be adjusted by adjusting the content of the inorganic filler. If the components such as the epoxy resin, the phenol resin, and the curing accelerator are the same, the bending elastic modulus tends to decrease as the content of the inorganic filler decreases. However, as the content of the inorganic filler is reduced, the heat shrinkage ratio exceeds the above range, or the amount of moisture absorption increases, so that the problem of peeling the semiconductor device during the soldering process and causing cracks is likely to occur. turn into. The content of the inorganic filler is preferably 80% by weight or more, although it may vary depending on the types of the epoxy resin and the phenol resin, because it does not cause problems such as peeling or cracking of the semiconductor device during soldering.

In the present invention, it is preferable that the epoxy resin and the phenol resin at least partially include the epoxy resin represented by the formula (1) and / or the phenol resin represented by the formula (2). Furthermore, the total amount of the epoxy resin represented by the formula (1) and the phenol resin represented by the formula (2) is 25 in the epoxy resin and the phenol resin.
It is more preferably ˜100% by weight. When the epoxy resin represented by the formula (1) and the phenol resin represented by the formula (2) are blended, the flexural modulus of the cured product of the epoxy resin composition can be reduced while the inorganic filler is highly filled. . When the total amount of the epoxy resin represented by the formula (1) and the phenol resin represented by the formula (2) in the epoxy resin and the phenol resin is 25% by weight or more, the stress generated when exposed to the heating step is reduced. By doing so, a sufficient flexural modulus can be obtained.

The epoxy resin composition used in the present invention is
In addition to the components (A) to (D), a brominated epoxy resin, a flame retardant such as antimony oxide, an inorganic ion exchanger such as bismuth oxide hydrate, and γ-glycidoxypropyltrimethoxysilane, if necessary. Coupling agents, carbon black, colorants such as red iron oxide, low stress components such as silicone oil and silicone rubber, natural wax, synthetic wax,
Various additives such as a release agent such as higher fatty acid and its metal salt or paraffin, and an antioxidant may be appropriately blended. Further, if necessary, the inorganic filler may be pretreated with a coupling agent, an epoxy resin or a phenol resin, and the treatment may be carried out by mixing with a solvent and then removing the solvent or by direct inorganic filling. There is a method of adding it to the material and treating it with a mixer.

The epoxy resin composition used in the present invention is
Components (A) to (D), other additives and the like are mixed at room temperature using a mixer, melt-kneaded by a kneader such as an extruder such as a roll or a kneader, cooled, and pulverized. The epoxy resin composition of the present invention can be used to seal a semiconductor element and manufacture an area mounting type semiconductor device by curing and molding by a molding method such as a transfer mold, a compression mold, an injection mold or the like.

Area mounted semiconductor devices of the present invention include BGA and LGA (Land Grid Array).
Package), QFN (Quad Flatpa)
ckNon-leaded Package) and the like.

[0021]

The present invention will be described below with reference to examples, but the invention is not limited to these examples. Example 1 Fused spherical silica A (average particle size 19 μm, specific surface area 2.8 m ² / g) 75.00 parts by weight Fused spherical silica B (average particle size 0.37 μm, specific surface area 14.4 m ² / g) 4. 00 parts by weight fused spherical silica C (average particle size 0.64 μm, specific surface area 4.4 m ² / g) 4.00 parts by weight fused spherical silica D (average particle size 0.61 μm, specific surface area 6.4 m ² / g) 4.00 parts by weight Epoxy resin represented by the formula (3) (softening point 58 ° C., epoxy equivalent 275) 2.23 parts by weight

[Chemical 5] Tetramethyl biphenyl diglycidyl ether (Yukaka Shell Epoxy Co., Ltd., YX-4000K, melting point 108 ° C., epoxy equivalent 185) 2.23 parts by weight Phenol aralkyl resin (Mitsui Chemicals, Inc., XL-225, softening point 62) C, hydroxyl equivalent 167) 3.63 parts by weight 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) 2.00 parts by weight Brominated bisphenol A type epoxy resin 0.50 parts by weight Antimony oxide 1.00 parts by weight γ-glycidylpropyltrimethoxysilane 0.20 parts by weight Carnauba wax 0.40 parts by weight Carbon black 0.30 parts by weight are mixed with a mixer at room temperature, and then two rolls at 70 to 120 ° C. Was kneaded, cooled and pulverized to obtain an epoxy resin composition. The obtained epoxy resin composition was evaluated by the following methods. The results are shown in Table 1.

Evaluation method Spiral flow: Using a mold for spiral flow measurement according to EMMI-1-66, the mold temperature was 175 ° C., the injection pressure was 6.9 MPa, and the curing time was 2 minutes. The unit is cm. Heat shrinkage rate: Using a transfer molding machine, mold temperature 17
4 mm × 5 ° C., injection pressure 9.8 MPa, curing time 2 minutes
A thermomechanical analyzer (Seiko Denshi Kogyo Co., Ltd., TMA100) was used for a test piece molded into a size of 4 mm × 15 mm.
Was measured at a temperature range of 0 to 320 ° C. and a temperature rising rate of 5 ° C./min. The rate of dimensional change between 30 to 175 ° C. and 175 to 260 ° C. was defined as the heat shrinkage rate. Units%. Flexural modulus: Measured in accordance with JIS K 6911 test conditions. The test piece had a mold temperature of 175 ° C. and an injection pressure of 9.
It was formed by using a transfer molding machine at 8 MPa and a curing time of 2 minutes, and post-curing at 175 ° C. for 8 hours. This test piece was placed on a measuring table (span width 64 mm), preheated for 6 minutes in a tank kept at the measurement temperature, and then measured. The measurement temperature is 260 ° C. The unit is N / mm ² . Water absorption rate: Using a transfer molding machine, mold temperature 175
℃, injection pressure 9.8MPa, curing time 2 minutes diameter 50m
m, 3 mm thick disk was molded and post-cured at 175 ° C for 8 hours, and the resulting molded product was left standing at 85 ° C and 60% relative humidity for 168 hours to measure the weight change and absorb water. I asked for the rate. The unit is% by weight. Separability of runners and gates, peeling failure rate of bonding pads: Mold temperature 1 using transfer molding machine
Batch encapsulation BGA at 75 ° C., injection pressure of 7.8 MPa, curing time of 150 seconds (substrate is a polyimide tape substrate of 0.1 mmt, encapsulation size is 53 × 189 mm, encapsulation thickness is 0.1.
6 mm, semiconductor element size is 5.11 x 9.36 m
m, thickness 0.32 mmt, the semiconductor element and the bonding pad of the circuit board are bonded with a gold wire having a diameter of 25 μm. The bonding pad, the runner, and the gate are plated with gold. Sixty-four semiconductor elements mounted on one substrate were molded, and the runner and the epoxy resin composition of the gate portion and the gold-plated portion of the obtained molded product were separated manually. At this time, when the epoxy resin composition remaining on the gold plating was less than 20%, the result was OK, and when the epoxy resin composition remaining on the gold plating was 20% or more, the result was NG. After that, it is post-cured at 175 ° C for 8 hours, and the obtained molded product is subjected to IR reflow treatment (260 ° C).
Then, the peeling of the inner gold plating after the treatment was observed with an ultrasonic flaw detector, and the number of peeled pieces was counted. There are a plurality of bonding pads around one semiconductor element, but if peeling was observed even at one of them, it was determined to be defective. When n defects out of 64 semiconductor devices occur, the defect rate is (n /
64) × 100. Solder crack resistance: 352 pBGA using a transfer molding machine at a mold temperature of 175 ° C., an injection pressure of 7.8 MPa, and a curing time of 2 minutes (the substrate is a bismaleimide / triazine resin / glass cloth substrate having a thickness of 0.56 mm, a semiconductor device) Size is 30 mm x 30 mm, thickness is 1.17 mm, semiconductor element size is 20 mm x 20 mm, thickness is 0.35 m
m, the bonding pad between the semiconductor element and the circuit board is 25
Bonding is done with a gold wire of μm diameter. A semiconductor element occupied area (44.4%) was molded and post-cured at 175 ° C. for 8 hours. After leaving the ten obtained semiconductor devices in an environment of 85 ° C. and a relative humidity of 60% for 168 hours, an IR reflow treatment (260 ° C.) was performed (hereinafter, referred to as L2). The presence or absence of internal peeling and cracks after the treatment was observed with an ultrasonic flaw detector, and the number of defective semiconductor devices was counted. When the number of defective semiconductor devices is n, it is displayed as n / 10.

Examples 2 to 9 and Comparative Examples 1 to 4 According to the formulations in Tables 1 and 2, epoxy resin compositions were obtained in the same manner as in Example 1 and evaluated in the same manner. The evaluation results are shown in Tables 1 and 2.

[0024]

[Table 1]

[0025]

[Table 2]

The resins used in other than Example 1 are shown below.
Phenol resin represented by formula (4) (softening point 65 ° C., hydroxyl equivalent 199)

[Chemical 6]

[0027]

According to the present invention, the runner and the separation of the epoxy resin composition from the gold plating on the printed wiring board of the gate part, and the bonding pad (which is gold-plated) at the time of stress generation inside the sealing, An epoxy resin composition for area-mounting type semiconductor encapsulation, which is compatible with the adhesiveness with the epoxy resin composition, can be obtained, and is industrially useful.

Continued front page    F-term (reference) 4J002 CD031 CD051 CD061 CD071                       DE136 DE146 DJ016 FD016                       GQ05 HA02                 4J036 AA01 AC18 AD01 AD04 AD07                       AD08 AF05 AF06 DA01 DA04                       FA12 FA13 FA14 FB07 JA07                       KA01                 4M109 AA01 BA04 CA21 EA02 EB03                       EB04 EB12

Claims (4)

[Claims] 1. (A) Epoxy resin, (B) Phenol
Resin, (C) curing accelerator, (D) inorganic filler as main components
In the epoxy resin composition to do, in all the inorganic filler,
10 to 30% by weight of particles of 1 μm or less are contained, and
Curing of a cured product of a epoxy resin composition in a 260 ° C. environment
Elastic modulus is 600 to 1000 N / mm ²And heat shrink
Rate is less than 0.25% at 30-175 ° C, 175-
Characterized by less than 0.20% at 260 ° C
Epoxy resin composition. 2. At least a part of the epoxy resin (A) is an epoxy resin represented by the formula (1), and / or at least a part of a (B) phenol resin is a phenol resin represented by the formula (2). Item 2. The epoxy resin composition according to Item 1. [Chemical 1] (In the formula, R ₁ and R ₂ are the same or different groups selected from alkyl groups having 1 to 4 carbon atoms. A is an integer of 0 to 3, b is an integer of 0 to 4, and n is an average value. And n is a positive number of 1 to 10.) (In the formula, R ₃ and R ₄ are the same or different groups selected from alkyl groups having 1 to 4 carbon atoms. C is an integer of 0 to 3, d is an integer of 0 to 4, and n is an average value. And n is a positive number of 1 to 10.) 3. The total amount of the epoxy resin represented by the formula (1) and the phenol resin represented by the formula (2) in the epoxy resin (A) and the phenol resin (B) is 25 to 10.
The epoxy resin composition according to claim 1, which is 0% by weight. 4. A semiconductor element is mounted on one side of a substrate, and the epoxy resin composition according to claim 1 is formed on substantially only one side of the substrate side on which the semiconductor element is mounted. A semiconductor device that is encapsulated by using.