JP2002179763A - Epoxy resin composition - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To provide a resin composition which shows extremely large heat dissipation when enclosing a high power generation IC chip. An epoxy resin composition used for sealing a semiconductor device, comprising: (A) a compound represented by the general formula (I): (Wherein, R1 to R8 may be the same or different,
Each is an atom or group selected from the group consisting of a hydrogen atom and an alkyl group. (B) a phenolic resin, and (C) a mixture of aluminum oxide (alumina) and silica filler constituting 80 to 92% by weight of the epoxy resin composition,
(A) a filler mixture wherein the ratio of the filler content (weight) to the total weight of the epoxy resin and (B) the phenol resin is at least 10.5 or more; and (D) 0.1% of the epoxy resin composition. The epoxy resin composition of the present invention comprises from about 0.4% to about 0.4% by weight of a curing accelerator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition used for encapsulation of a semiconductor device. The epoxy resin composition exhibiting solder stress property, coplanarity (also referred to as “sleigh” meaning z-axis displacement between two balls located at the farthest corners), and good high-temperature storage (HTSL) behavior It is about things. It is also an environmentally friendly material ("green plastic") because it does not contain halogens, antimony and these compounds. Due to such characteristics, this kind of thermosetting material can be recycled.

[0002]

2. Description of the Related Art Electronic components such as diodes, transistors and integrated circuits are sealed with a thermosetting resin. Particularly, in an integrated circuit, an epoxy resin having excellent heat resistance and moisture resistance is used as such a thermosetting resin.

As the degree of integration of integrated circuits increases, the size of chips increases, and
IP has gradually been replaced by thin, flat packages such as SOP, SOJ, PLCC, especially QFP. Now the industrial trend is BGA, chip size package (CS
P), flip chips (FC), non-lead packages, etc.

[0004] Apart from a reduction in the package size to chip size ratio, today's integrated circuits (ICs) also require higher operating speeds and higher power to provide higher junction temperatures. These can lead to higher device failure rates in some cases unless adequately addressed. Typically, additional heat dissipating materials or heat slugs are used to meet these requirements, but at the expense of system changes. Thermally enhanced molding compounds (TEMCs) with high heat dissipation capabilities are a useful alternative to meet such demands.

[0005] As ICs become more integrated, chips become larger and surface mount packages become thinner.
Inevitably, problems such as generation of cracks due to stress and deterioration of moisture resistance caused by the cracks are unavoidable.

[0006] Especially in the soldering process, the package is suddenly exposed to a high temperature of 200 ° C or higher, which leads to cracking of the package or peeling of the sealing resin from the chip, resulting in reduced moisture resistance.

In order to fix one side of a ball grid array or the like to a mold package as in an embedded process, severe coplanarity conditions must be satisfied. Therefore, the “sleigh” generated in the embedded package must be kept to a minimum.

[0008]

To summarize all the above requirements, an epoxy resin composition that can be used appropriately for encapsulating high power ICs and that satisfies the same planarity conditions and environmental issues. It is desired to develop.

[0009]

In order to impart high thermal conductivity to the resulting resin composition or epoxy molding compound (EMC), it is necessary to mix a relatively large amount of spherical alumina. EMC is a typical example of a continuous matrix of polymer containing ceramic particles and is also referred to as fine particle filled polymer (PFP).

The present invention relates to a compound of the general formula (I) which has a relatively low viscosity and thus allows more alumina and silica filler in the resin composition.

Embedded image Is used. The resulting EMC has high thermal conductivity, relatively low thermal expansion, relatively low water absorption and relatively high solder stress.

[0011] It is an object of the present invention to provide a resin composition which exhibits extremely large heat dissipation when a high power generating IC chip is encapsulated. Besides, it shows good coplanarity (for BGA), solder cracking resistance,
Has behavior as a potentially eco-friendly thermoset material.

According to the present invention, there is provided an epoxy resin composition used for encapsulating a semiconductor device, the resin composition comprising the following as essential components: (A) General formula (I)

Embedded image Wherein R1 to R8 may be the same or different and each is an atom or group selected from the group consisting of a hydrogen atom and an alkyl group, an epoxy resin of a biphenyl type epoxy compound, (B ) 20 to 100% by weight, based on the total amount of the phenolic resin-based curing agent, of the general formula (II)

Embedded image A phenolic resin-based curing agent containing a para-xylene-modified phenolic resin-based curing agent represented by the formula (n is an integer of 0 to 5), thereby encapsulating a semiconductor having extremely high resistance to soldering stress. (C) 80 to 9 of the total epoxy resin composition
An inorganic filler mixture comprising aluminum oxide and silica oxide occupying 2% by weight; (D) a curing accelerator, preferably in an amount of 0.1 to 0.4% by weight, based on the total epoxy resin composition; The resin (A) is used in an amount of 0.8 to 1.2 epoxy equivalents per equivalent of the hydroxy group of the phenol resin-based curing agent (B).

The environmentally friendly epoxy resin compositions of the present invention have very high heat dissipation and soldering stress resistance as compared to conventional resin compositions used for the same purpose.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An epoxy resin of a thermally reinforced mold compound (TEMC) is a bifunctional epoxy resin represented by the above general formula (I) and having two epoxy groups in a molecule, During molding, it exhibits low melt viscosity and excellent fluidity compared to conventional multifunctional epoxy resins. As a result, the composition of the present invention can include a large amount of alumina and silica fillers, and can exhibit high thermal conductivity, low coefficient of thermal expansion, low hygroscopicity, and excellent solder stress.

The solder stress property of the present invention can be maximized by adjusting the amount of the biphenyl type epoxy resin used for the component (A). The chosen hydrophobic epoxy resin provides low water absorption and high curability, which means that it can carry a large amount of filler. These in turn mean a mold compound with high thermal conductivity, reduced coefficient of thermal expansion, good solder cracking resistance and low hygroscopicity.

In order to obtain high soldering stress resistance, it is desirable to use the biphenyl type epoxy resin represented by the general formula (I). Such an epoxy resin composition results in a decrease in coefficient of thermal expansion, a decrease in hygroscopicity, and excellent solder stress. In the general formula (I), R1 to R4
Is preferably a methyl group, and R5 to R8 are each preferably a hydrogen atom.

Another epoxy resin is represented by the general formula (I)
When used in combination with the above biphenyl type epoxy resin, the other epoxy resin is an ordinary polymer having an epoxy group. For example, bisphenol type epoxy resin, cresol novolak type epoxy resin, phenol novolak type epoxy resin, trifunctional epoxy resin (for example, triphenolxetane type epoxy resin and alkyl-modified triphenolmethane type epoxy resin) and tri-azine nucleus Containing epoxy resin.

The phenolic resin-based curing agent represented by the general formula (II) has a relatively flexible structure in its molecular structure and is a flexible phenolic resin-based curing agent. This curing agent provides the resulting resin composition with a lower modulus of elasticity and higher adhesion to lead frames, substrates and semiconductor chips at soldering temperatures, as compared to phenol novolak type resin curing agents and the like. Thus, the general formula (II)
The curing agent of (a) lowers the stress generated during soldering, and (b) effectively prevents separation from a semiconductor chip or the like.

The general formula (II) used for the component (B)
By adjusting the amount of the phenolic resin-based curing agent, the solder stress property of the epoxy resin composition of the present invention can be maximized. The resulting resin composition can reduce the modulus of elasticity, enhance the adhesion to lead frames, substrates, and semiconductor chips, and obtain higher soldering stress resistance.

In the general formula (II), n is from 0 to 5
Must be an integer up to. When n is greater than 5, the flowability during transfer molding and the molding aptitude tend to be reduced.

The mixing ratio of the epoxy resin (A) to the phenolic resin-based curing agent (B) is such that the epoxy resin (A) is 0.8 per equivalent of the hydroxy group of the phenolic resin-based curing agent (B). It is preferably used so as to have an equivalent weight of from 1.2 to 1.2 epoxy. Outside the above range, properties such as moisture resistance tend to deteriorate.

The thermal conductivity of a typical resin composition is greatly affected by the type and content of the ceramic filler present in the resin matrix. To get the maximum heat dissipation capacity,
Alumina (thermal conductivity ３０30 W / mK) is selected as the primary filler instead of conventional fused silica (thermal conductivity １1.3 W / mK).

The amount of filler added must be at least 80% by weight of the total epoxy resin composition, preferably at least 84% by weight. If the amount of filler is less than 80% by weight, the resulting composition is insufficient to increase thermal conductivity and reduce thermal expansion. On the other hand, if the amount of the filler exceeds 92% by weight, the fluidity of the resulting resin composition may decrease.
Therefore, the acceptable filler content must be 80-92% by weight. Carefully selected fine fused or crystalline silica facilitates the flow of the molten resin composition during transfer molding and also helps reduce air vent burrs.

Typical filler distributions meeting the above criteria are preferably (i) 0.5-1.0 μm, (ii) 6.0-3.
Three peaks must be formed in the region of 0.0 μm and (iii) 30.0-100.0 μm. The lowest point of the saddle between 1.0 μm and 6.0 μm should be at least 0.5%, more preferably more than 1.0% of the total epoxy resin composition. The minimum peak (i) consists of a fine silica filler which is essentially either fused silica or crystalline silica. These fine fillers act as lubricating bearings to promote flow and minimize air bleed flush during transfer molding. If the amount of such filler is too large or too small, these functions may not be fulfilled. In the present invention, the filler of the peak (i) and the saddle portion is cleverly designed to occupy 3.0 to 6.0% by weight of the total resin composition, and the maximum size is 8 μm or less. Fillers exceeding 8 μm are ineffective for performing the above functions.

In addition, spherical fillers and broad filler distributions are necessary to maintain good fluidity and processability. The spherical filler also helps to reduce the abrasiveness and elastic modulus of the resin composition.

For BGA and other one-side mold packages, accurate coplanarity is an important prerequisite for surface mounting. Warpage is often the result of a thermal mismatch between the substrate and the encapsulant, which usually has a higher coefficient of thermal expansion than the former. With higher filler loading, the coefficient of thermal expansion (CTE) of EMC as well as thermal shrinkage is reduced, and the resulting warpage can be minimized.

Another critical role of the alumina filler in the resin composition of the present invention is its role as a flame retardant. The microscopic presence of water on the surface of the alumina hydrolyzes the filler to produce aluminum hydroxide. During the heating or combustion process, these metal hydroxides undergo an endothermic reaction, releasing their contained moisture and returning to alumina. By doing so, it provides the essential flame retardancy to the organic resin network.

In addition, during combustion, the radicals of the organic resin combine with the alumina filler to form aluminum hydroxide, a flame retardant. [Al ₂ O ₃ + 6OH ⁻ → 2Al (OH) ₃ + 3O ^2- ]

Due to the mechanism described above, the resin composition of the present invention does not contain any conventional flame retardants such as brominated epoxy resins. The result is an environmentally friendly EMC that is free of bromine, antimony and boron compounds. Another consequence is that expensive alumina-filled resin compositions can be recycled.

However, the resin composition without additional flame retardant must contain a relatively large amount of filler in order to pass the UL-094 (Underwriters Laboratory-USA) V-0 flammability standard. Must. Passing the V-0 standard is when the ratio of total filler content (FC, wt%) to total resin content (RC, wt%) reaches a minimum value of 10.5. Below this minimum threshold the material is U
It becomes V-1 of the L-94 standard.

The curing accelerator used in the present invention may be any material as long as it can promote the reaction between the epoxy group of component (A) and the hydroxyl group of component (B). Generally used as a sealing material, for example, diazabicycloundecene (DBU), triphenylphosphine (TP
Curing accelerators such as P), benzyldimethylamine (BDMA), and 2-methylimidazole (2-MZ) are widely used. These compounds can be used alone or in combination of two or more.

[0032] The curing accelerator is used in an amount of 0.1% of the total epoxy resin composition.
It is preferred to use an amount of 1 to 0.4% by weight. 0.1
If the amount is less than% by weight, the hardness of the formed molded product tends to decrease and the releasability tends to deteriorate. If the amount is more than 0.4% by weight, the reaction proceeds unfavorably quickly and the fluidity tends to decrease.

The epoxy resin composition of the present invention used for sealing contains an epoxy resin, a curing agent, an inorganic filler and a curing accelerator as essential components. If necessary, the resin composition may further contain various additives such as a silane coupling agent, a release agent (such as a natural wax or a synthetic wax), and a stress suppressant (such as silicone oil or rubber).

When the encapsulating epoxy resin composition of the present invention is produced as a molding material, the epoxy resin, curing agent, curing accelerator, filler and other additives are sufficiently and uniformly mixed using a mixer or the like. Mixing; then melt kneading the mixture using a hot roll, kneader, etc .; cool and mill the kneaded product. The molding material thus obtained is used for sealing or coating electronic or electric components.
Used for insulation etc.

According to the present invention, an environmentally friendly resin composition having particularly high thermal conductivity, low thermal expansion and low water absorption can be obtained. Such a combination has not been achieved in the prior art.

At the package level, these are (a) good heat dissipation to meet the requirements of high power devices, (b) good solder cracking resistance, (c) low warpage, (d)
In other words, high HTSL performance and (e) recyclability of excess mold material. The epoxy resin composition of the present invention can be used as an electronic component or an electrical component, especially one-side and both-side molded high-output integrated chip ICs for surface mounting purposes.
Can be used for sealing, coating, insulation and the like.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the following embodiments. In the examples, the amounts of each component used in the formulation are expressed in parts by weight.

Example 1 The following components were mixed at the following ratio at room temperature using a mixer, and mixed using a twin-screw roll.
It is kneaded at 0 to 100 ° C., cooled and pulverized to obtain a molding material. General formula (III)

Embedded image Epoxy compound (softening point: 108 ° C., epoxy equivalent:
185 g / equivalent): 4.8 parts by weight General formula (II)

Embedded imageParaxylene-modified phenolic resin-based curing agent (softening point:
64-69 ° C, epoxy equivalent: 175 g / eq): 1.
2 parts by weight phenol novolak resin-based curing agent (softening point: 90
° C, hydroxyl equivalent: 105 g / eq): 1.5 fold
Quantity  Alumina filler 86.5 parts by weight Fused silica filler 4.0 parts by weight Diazabicycloundecene (DBU) 0.2 parts by weight Silane coupling agent 0.5 parts by weight Stress suppression additive 0.7 parts by weight Carbon black 0.7 parts by weight 2 parts by weight0.4 parts by weight of release agent  Performance tests at the package level show similar pellets.
Start by making the objects in various sizes. For testing purposes
Depending on the temperature, 175 ° C, 50-80kgf / cm^TwoAt 6
(I) 2 for 2 seconds on an organic substrate having a solder resist
27 × 27mm overmold with 56 balls
Dead plastic ball grid array (O
MPBGA) or 35 x 35m with 352 balls
It can be molded into mPBGA. Then smaller
Package with a large chip (6 x 6 mm) is warped.
5 hours post-mold cure (PMC) at 175 ° C before
receive. (Ii) that has a larger chip in it;
Other package (14 × 14mm, polyimide (P
I) coating) is exposed to air at 60 ° C./60% RH for 120 hours.
Be sent. (Iii) Similarly, the pellets are at a temperature of 175
° C, 100kgf / cm^TwoFor 120 seconds, PI and Si
9 x 9 mm size coated with N (silicon nitride)
80-pin QFP (14 x 20 mm) encapsulating the chip
Molded. After molding, the air vent burr
Measure the average length. Air vent depth ~ 25-30
For 35 × 35 mm PBGA with μm,
Has a length of about 0.5 to 1.0 mm. Then,
Cages are sent for PMC at 175 ° C. for 4 hours.

Thereafter, the package has a peak temperature of 235.
Sent through various temperature profiles according to JEDEC standards in an infrared (IR) oven at 0 ° C. afterwards,
All cracks present on the surface of the device are observed using a microscope. In addition, these packages are
Using a (C-mode scanning acoustic microscope), the flake interlayer is scanned focusing on the apex of the chips and the substrate molding compound (iii) with these chips to obtain a device for the solder cracking test. 16p tablet
DIP (16-pin dual in-line package), HTSL test at 175 ° C, and then test circuit resistance at a value exceeding 1.0Ω (the electrical resistance value after molding is generally < During continuous high temperature exposure, free ions present in the encapsulant, especially bromide and antimony, erode the gold ball bonds, forming, for example, Kirkendall voids, which have higher electrical resistance. Lead to). The result is represented by the average life.

In the measurement of the thermal conductivity of EMC, a tablet was first prepared and then formed into a cylindrical mass having a diameter of 40 mm and a height of 25 × 5 mm at 175 ° C. and 150 kgf / cm ² for 300 seconds using a low-pressure transfer molding machine. I do.

(Examples 2 to 3) The epoxy resin compositions were blended into the respective formulations shown in Table 1, and the same operation as in Example 1 was performed to obtain a molding material. Devices for test purposes are manufactured using these molding materials and subjected to warpage, soldering resistance and HTSL tests. The results are shown in Table 1.

(Comparative Examples 1 to 5) The epoxy resin compositions were blended into the respective formulations shown in Table 1, and the same operation as in Example 1 was performed to obtain a molding material. Devices for test purposes are manufactured using these molding materials and subjected to a solder crack test. They included as benchmarks three established grades with significant performance for specific applications, and included two intermediate samples under development. Table 1 shows the results.

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 23/29 H01L 23/30 R 23/31 (72) Inventor Tat Hong Tan Singapore, Singapore 461001 ♯08 −210, Chai Chi Road, BB Kay 1 (72) Inventor Naoki Mogi Singapore, Singapore 596746, Signature Park ♯04−12, Totak Road, BK Kay 56 (72) Inventor Lee Lin Ann Malaysia, Johor, Johor Jaya 81100 JB, Jalan Pesona Taman, 101F Term (Reference) 4J002 CC03X CC27X CD04W DE146 DJ016 FD016 FD157 GQ05 4J036 AD07 DA02 FA02 FB07 FB08 JA07 4M109 AA01 EB03 EB03 EB03 EB03 EB03 EB03

Claims (8)

[Claims] An epoxy resin composition used for encapsulating a semiconductor device, comprising: (A) a compound represented by the following general formula (I): (Wherein, R1 to R8 may be the same or different,
Each is an atom or group selected from the group consisting of a hydrogen atom and an alkyl group. (B) a phenolic resin, and (C) a mixture of aluminum oxide (alumina) and silica filler constituting 80 to 92% by weight of the epoxy resin composition. The mixture of (A) epoxy resin and (B) the total weight of phenolic resin is at least 10.5 or more and (D) 0.1 to 0.4 of the epoxy resin composition.
An epoxy resin composition comprising, by weight, a curing accelerator. 2. The method according to claim 1, wherein the epoxy resin (A) is used in an amount such that the epoxy equivalent is 0.8 to 1.2 times per hydroxyl equivalent of the phenol resin (B). Epoxy resin composition. 3. The phenolic resin (B) has a general formula (I)
I) 3. The epoxy resin composition according to claim 1, wherein the phenolic resin (where n is an integer of 0 to 5) is contained in an amount of 20 to 100% by weight of the total phenolic resin. 4. The epoxy resin composition according to claim 1, wherein said alumina and silica filler mixture contains a silica filler having a maximum particle size of 8 μm or less. 5. The method according to claim 1, wherein said silica filler constitutes 3 to 6% by weight of the epoxy resin composition.
Item 10. The epoxy resin composition according to Item 1. 6. The V of UL-94 even when a flame retardant is not present.
The epoxy resin composition according to any one of claims 1 to 5, wherein the epoxy resin composition can reach a flame retardancy of -0 standard. 7. A semiconductor device manufactured by using the epoxy resin composition according to claim 1. 8. A method for manufacturing a semiconductor device, comprising: providing an epoxy resin composition to the semiconductor device;
A method for manufacturing a semiconductor device, wherein the epoxy resin composition is an epoxy resin composition as defined in any one of claims 1 to 6.