JP2621429B2 - Epoxy resin composition for semiconductor encapsulation - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an epoxy resin composition for semiconductor encapsulation.

[Conventional technology]

In general, epoxy resin compositions have excellent electrical properties, heat resistance, adhesion, moisture resistance, etc., and have low-pressure moldability,
Utilizing these properties, it is used in a wide range of fields such as semiconductor sealing materials, printed circuit board materials, casting materials, and adhesives.

Above all, as disclosed in, for example, JP-A-63-77930, a combination of a novolak type epoxy resin and a phenol novolak resin provides high heat resistance and moisture resistance, and thus is widely used as a semiconductor sealing material. Have been.

However, when a large element (for example, a highly integrated memory) is sealed during curing or during a cooling process due to the generation of a large thermal stress during the curing or the resin composition, the element function is deteriorated due to the thermal stress applied to the element circuit. Or, a disadvantage such as a package crack occurs.

One of the causes is that the coefficient of thermal expansion of a semiconductor element, a frame material, and the like is significantly smaller than that of an epoxy resin composition. Such a difference in the coefficient of thermal expansion is
Thermal stress is induced in the cooling process after molding and post-curing, causing the above-mentioned inconvenience, and the above-mentioned inconvenience is correlated with thermal stress and bending strength. National Conference Proceedings P2-148]
A reduction in thermal expansion coefficient, a reduction in thermal stress due to a reduction in elastic modulus, and an improvement in bending strength lead to the elimination of the above-mentioned disadvantages.

For this reason, a method of increasing the amount of the inorganic filler to be added or modifying the inorganic filler with a silicone compound has been studied.

[Problems to be solved by the invention]

However, in order to increase the amount of the inorganic filler added, lower the coefficient of thermal expansion, and improve the effect on package cracks, etc., it is necessary to use 80% (% by weight, the same applies hereinafter) or more. Since the novolak type epoxy resin and the phenol novolak resin system are solid at room temperature, high loading of the inorganic filler leads to an increase in the melt viscosity of the resin composition, and significantly impairs the moldability. In addition, an increase in the melt viscosity causes a gold wire flow or disconnection at the time of molding, resulting in an undesirable state.

On the other hand, in the modification with a silicone compound, a method of reacting and modifying a silicone compound with a novolak type epoxy resin or a phenol novolak resin is generally used, and this modification method uses a high molecular weight of a novolak type epoxy resin or a phenol novolak resin. And the fluidity of the resin composition to which the inorganic filler is added is impaired, resulting in an undesirable state.

The present invention has been made in order to solve such a problem, and even if the amount of the inorganic filler is increased, or the thermal stress is reduced by modification with a silicone compound, the fluidity of the composition is improved, It is another object of the present invention to obtain an epoxy resin composition for semiconductor encapsulation which does not change the excellent heat resistance, moisture resistance and cold shock resistance of the cured epoxy resin.

[Means for solving the problem]

The epoxy resin composition for semiconductor encapsulation of the present invention has a chemical formula (A), a phenolic novolak resin having a softening point of 90 to 130 ° C. (b), 80 to 90% by weight of an inorganic filler and a curing accelerator, and an epoxy group of the epoxy resin (a) And the equivalent ratio of the phenolic hydroxyl groups of the phenol novolak resin (b) is 0.8 to 1.2 with respect to the epoxy group.

[Action]

The epoxy resin in the present invention is liquid at room temperature,
In addition, because of the planar structure, the packing property of the cured product is increased, and it is considered that the above-described effects are produced. That is, by using the epoxy resin (a), even if the inorganic filler is contained in a large amount as described above in order to reduce the thermal expansion, or even if a curing agent having a high softening point is used, the flow of the composition can be improved. The cured product does not change the excellent heat resistance and mechanical properties of the epoxy resin.

〔Example〕

The epoxy resin (a) according to the semiconductor epoxy resin composition of the present invention has a chemical formula It is preferable to use an epoxy resin containing as few chlorine ions and chlorine-containing compounds as possible in the epoxy resin.

Further, a flame-retardant brominated novolak epoxy resin and a brominated bisphenol A type epoxy resin may be used together with this epoxy resin, if necessary. In this case, the amount of these epoxy resins used is the
It is preferably 50 parts by weight or less based on 0 parts by weight.

The phenol novolak resin (b) relating to the semiconductor epoxy resin composition of the present invention is obtained by subjecting a phenolic compound such as phenol, cresol, xylenol, bisphenol A, resorcin, and the like to a condensation reaction with formaldehyde or paraformaldehyde under an acidic catalyst. The softening point obtained by the reaction is 90 to 130 ° C., and the unreacted monomer is obtained in the obtained phenol novolak resin.
It is preferably at most 0.5% by weight.

Further, a silicone-modified phenol novolak resin may be used in combination, and it can be obtained by reacting the above-obtained phenol novolak resin with, for example, an epoxy-modified silicone using triphenylphosphine as a catalyst.
When the softening point of the phenolic novolak resin is less than 90 ° C, the glass transition temperature of the cured product decreases, heat resistance and moisture resistance deteriorate, and when the temperature exceeds 130 ° C, the melt viscosity of the epoxy resin composition increases. Adversely affect workability.

In the epoxy resin composition for semiconductor encapsulation according to the embodiment of the present invention, the mixing ratio of the epoxy resin and the phenol novolak resin is such that the phenolic OH equivalent of the phenol novolak resin is 0.8 per equivalent of epoxy group of the epoxy resin.
~ 1.2 equivalents. When the phenolic OH equivalent of the phenol novolak resin is less than 0.8 with respect to 1 equivalent of the epoxy group of the epoxy resin, the glass transition temperature of the composition is lowered, and the moisture resistance and heat resistance are reduced.
When the OH equivalent exceeds 1.2, a large amount of phenol novolak resin remains in the cured product as an unreacted product, and the moisture resistance and heat resistance are reduced.

Examples of the inorganic filler used in the epoxy resin composition for semiconductor encapsulation of the embodiments of the present invention include crystalline silica powder, fused silica powder, alumina powder, talc, quartz glass powder, calcium carbonate powder, glass fiber and the like. can give.
The amount of the inorganic filler to be added is preferably 80 to 90% in the composition. If it is less than 80%, the effect of lowering the coefficient of linear expansion and curing shrinkage will be small, and if it exceeds 90%, the fluidity will decrease and the workability tends to decrease.
It is preferable to appropriately select the compounding amount in the range of 80 to 90% according to the required characteristics.

Examples of the curing accelerator used in the epoxy resin composition for semiconductor encapsulation according to the examples of the present invention include 2-methylimidazole, 2-ethylimidazole, and 2-ethyl-imidazole.
Imidazole compounds such as 4-methylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 2-undecylimidazole; 2-
(Dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, benzyldimethylamine, α-methylbenzyldimethylamine, piperidine, dimethyllaurylamine, dialkylaminomethanolamine, tetramethylguanidine, 2-dimethyl Amino-2-hydroxypropane, N, N'-dimethylpiperazine, N-methylmorpholine, piperazine, 2-
Tertiary amines such as (dimethylaminomethyl) phenol, hexamethylenetetramine, 1-hydroxyethyl-2-heptadecylglyoxalidine, 1,8-diazabicyclo (5,4,0) undecene-7 and other amines Compounds, imidazole compounds, phosphorus compounds such as triphenylphosphine and the like can be mentioned. Since the amount of the curing accelerator added varies depending on the type of the curing accelerator, it cannot be determined unconditionally, and the present invention is not limited by the amount of addition.
It is preferably 0.1 to 5 parts by weight with respect to 0 parts by weight.

The epoxy resin composition for semiconductor encapsulation of the present invention may contain a coloring agent such as carbon black, a mold release agent such as carnauba wax, polyethylene wax, a flame retardant such as antimony trioxide, and γ-glycyloxy, if necessary. The content of a coupling agent such as propyltrimethoxysilane, a rubber component such as silicone rubber or fluorine rubber in the composition is reduced.
You may add in the range which does not exceed 10%.

Further, the epoxy resin composition for semiconductor encapsulation of the present invention,
It can be easily prepared using a commonly used known mixing device, for example, a roll, a kneader, a Raikai machine, a Hensiel mixer (manufactured by Mitsui Miike Seisakusho) and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to only these Examples.

Examples 1 to 8 and Comparative Examples 1 to 7 An epoxy resin, a phenol novolak resin, an inorganic filler, a curing accelerator and other components were prepared so as to have the composition shown in Table 1, and heated at 80 to 110 ° C. After kneading for 5 to 7 minutes and pulverizing, a tablet was formed under a pressure of 1100 to 1500 kg / cm ² . The fluidity was determined according to the EMMI method.

The silicone-modified phenol novolak resin used in Example 7 and Comparative Example 2 was produced as follows. That is, 500 g of phenol novolak having a softening point of 96 ° C. is placed in the four-necked flask 1 and heated to 130 ° C. in a nitrogen stream to be uniformly melted. Thereafter, 2 g of triphenylphosphine was added, and 300 g of an epoxy-modified silicone oil (epoxy equivalent: 850: manufactured by Shin-Etsu Chemical Co., Ltd.) was added at a dropping funnel at 150 ° C.
The reaction was carried out to obtain a silicone-modified phenol novolak resin. The reaction rate is 95 from the titration of the epoxy group.
%.

Then, using the tablet obtained as described above,
Mold temperature is 180 ℃ ± 5 ℃, plunger pressure is 80kg / c
m ² , transfer molding under the condition of molding time 90 seconds,
Various monitor chips for evaluation of reliability and various test specimens for evaluation were prepared respectively, and the monitor chip for reliability evaluation and the test specimen for each evaluation were subjected to 175 ° C,
A post-curing treatment was performed for 8 hours.

Further, using the tablets obtained as described above and test pieces for evaluation, each of the flexural modulus, the bending strength, the linear expansion coefficient, the glass transition temperature and the fluidity was measured. Table 2 shows the results.

In addition, in Comparative Example 2, the fluidity was poor, and it was impossible to produce various test pieces for evaluation.

Further, using each of the monitor chips for reliability evaluation obtained as described above, a heat resistance test, a humidity resistance test and a cold heat cycle test were conducted by the following means. Table 2 shows the results.

“Heat Resistance Test” The time until a failure occurred in the monitor chip was measured at 250 ° C. in air.

"Moisture resistance reliability test" The condition was evaluated by the number of defective monitor chips after 1,000 hours under the condition of PCT (Pressure Cooker Test) of 130 ° C and 2.7 atm.

“Cooling and heat cycle test” One cycle of 30 min at -65 ° C and 30 min at 150 ° C
Evaluation was made based on the number of defective monitor chips after 00 cycles.

That is, as can be seen from Table 2, when the epoxy resin composition for semiconductor encapsulation in this example was used, a decrease in the glass transition temperature was prevented, and the bending strength and the fluidity of the composition were not impaired. In addition, thermal stress can be reduced. On the other hand, in Comparative Examples 5 and 6, by lowering the glass transition temperature,
Although the thermal stress value has decreased, as can be seen from the heat resistance test results of the monitor chips in Table 3, the decrease in heat resistance has been observed. Imitating

Also, in comparison with Example 7 and Comparative Example 2 using the low stress prescription, Example 7 can achieve a large reduction in stress without significantly impairing the fluidity.

Further, as can be seen from Table 3, the monitor chip for evaluation also has very excellent heat resistance, moisture resistance, and cooling / heat cycle resistance.

〔The invention's effect〕

As described above, the present invention provides (A), a phenol novolak resin having a softening point of 90 to 130 ° C. (b), 80 to 90% by weight of an inorganic filler and a curing accelerator, and an epoxy group of the epoxy resin (a) When the equivalent ratio of the phenolic hydroxyl group of the phenol novolak resin (b) is 0.8 to 1.2 with respect to the epoxy group, the amount of the inorganic filler to be added can be increased or modified by a silicone compound. Even when the thermal stress is reduced, the fluidity of the composition is improved,
And the cured product also has excellent heat resistance of epoxy resin,
It is possible to obtain an epoxy resin composition for semiconductor encapsulation that does not change moisture resistance and cold shock resistance, for example, IC and
It can be used for LSI.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsuko Shinda 8-1-1, Tsukaguchi-Honcho, Amagasaki-shi, Hyogo Pref. Inside the Materials Research Laboratory, Mitsubishi Electric Corporation (72) Inventor Norimoto Moriwaki 8-1-1, Tsukaguchi-Honcho, Amagasaki-shi, Hyogo No. 1 Inside Mitsubishi Materials Corporation Materials Research Laboratory (56) References JP-A-63-77930 (JP, A) JP-A-63-142023 (JP, A) JP-A-61-293219 (JP, A) 60-124647 (JP, A) JP-A-63-128020 (JP, A) JP-B-51-20541 (JP, B1) "Electronic materials" December issue (Vol. 25, No. 12) (Showa 61-12-) 1) Industrial Research Institute Co., Ltd. 66-73

Claims (1)

(57) [Claims] (1) Chemical formula An epoxy resin (a), a phenol novolak resin (b) having a softening point of 90 to 130 ° C., an inorganic filler of 80 to 90% by weight and a curing accelerator, and an epoxy group of the epoxy resin (a) An epoxy resin composition for semiconductor encapsulation, wherein the equivalent ratio of the phenolic hydroxyl group of the phenol novolak resin (b) is 0.8 to 1.2 with respect to the epoxy group.