JP2000336244A - Liquid sealing resin composition and semiconductor device using the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid sealing resin composition for sealing semiconductor elements, etc., which does not deteriorate its pot life, is cured within a shorter time compared to the conventional resin composition and provides a reliability comparable to that of the conventional resin systems, and a reliable semiconductor device having a high productivity. SOLUTION: A liquid sealing resin composition comprises (A) a liquid epoxy resin having two or more epoxy groups in average, (B) an aromatic amine hardener which is in the liquid state at an ordinary temperature, (C) an imidazole having a hydroxy group and (D) silica. Preferably, the aromatic amine hardener is an alkylated diaminodiphenylmethane. A semiconductor device is prepared by sealing a semiconductor element using the above-mentioned liquid sealing resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid sealing resin composition used for sealing a semiconductor and a semiconductor device.

[0002]

2. Description of the Related Art In recent years, as semiconductor chips have become larger, packages have more pins, and diversification, the demand for reliability of resin materials as peripheral materials has been stricter year by year.
Conventionally, a package in which a semiconductor chip is bonded to a lead frame and sealed with a mold resin has been mainstream. However, a package such as a ball grid array (BGA) has been considerably increased due to the limit of increasing the number of pins.

[0003] The BGA is sealed with a molding resin or a liquid resin. BGA is for substrate, solder resist, gold,
Since it is composed of a plated portion of nickel or the like, its adhesion to them is important. In addition, solder crack resistance is required for bonding to a motherboard by a surface mounting method. Furthermore, there is a temperature cycle test (T / C test) as a part of reliability, and high reliability is required for the package.

As a material satisfying these requirements, a liquid epoxy resin / alkyl-substituted aromatic diamine-based liquid sealing resin composition has been proposed. (JP-A-07-341580, 07-341
582) This material has excellent adhesion to substrates, metals, solder resists, etc., and also has excellent solder reflow resistance and T / C crack resistance, enabling highly reliable packages.

However, the above-mentioned resin system has a long curing time (for example, 150 ° C., 3 hours), and is problematic from the viewpoint of package productivity. Filler sedimentation occurs due to the long gelation time during curing, and a layer containing a large amount of resin components is formed on the surface of the cured product. Under severe conditions in the T / C test,
In some cases, surface cracks were generated with an increase in the coefficient of linear expansion of the surface of the cured product. Further, in order to shorten the curing time, addition of a curing accelerator may be considered, and examples thereof include phenols, but there are drawbacks such as the pot life is too short and the workability is extremely deteriorated. .

[0006]

SUMMARY OF THE INVENTION In a liquid sealing resin composition for sealing a semiconductor element or the like, the resin can be cured in a shorter time than before without impairing the pot life and the reliability of the conventional resin can be improved. A liquid sealing resin composition having the same properties as the system is provided.

[0007]

The inventors of the present invention have conducted intensive studies in order to solve the conventional problems as described above. As a result, liquid epoxy resins and aromatic amine-based curing agents which are liquid at ordinary temperature have been developed. By adding imidazole having a hydroxyl group to the above, it has been found that curing can be performed in a shorter time than before without impairing the pot life, and that the reliability has the same properties as those of the conventional resin system. It has been completed.

That is, (A) a liquid epoxy resin having an average epoxy group of 2 or more, (B) an aromatic amine-based curing agent which is liquid at ordinary temperature, (C) an imidazole having a hydroxyl group,
(D) A liquid sealing resin composition comprising silica. In a more preferred embodiment, the aromatic amine-based curing agent is an alkylated diaminodiphenylmethane, and at least 50% by weight of the liquid epoxy resin has a viscosity at 25 ° C of 10%.
An epoxy resin of PA · s or less, wherein the mixing molar ratio of the liquid epoxy resin and the aromatic amine-based curing agent is 1.1 to 1.3.
The liquid sealing resin composition contains a larger amount of the liquid epoxy resin in the range described above. Further, the present invention is a semiconductor device in which a semiconductor element is sealed using the above liquid sealing resin composition.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The liquid epoxy resin (A) used in the present invention has an average of two or more epoxy groups per molecule, and 50% by weight or more of the component is 25% by weight.
It is preferable that the epoxy resin has a viscosity at 10 ° C. of 10 PA · s or less. Unless 50% by weight or more of the epoxy resin component is a low-viscosity liquid epoxy, the viscosity of the composition increases,
When the inside of the package is sealed with a liquid sealing material, bubbles are entangled and poor filling of corner ends is apt to occur, leading to a reduction in reliability, which is not preferable.

The method for measuring the viscosity of the epoxy resin is as follows.
It is measured at 5 ° C. with an E-type viscometer manufactured by Toki Sangyo Co., Ltd.
There is no particular limitation as long as the epoxy resin satisfies these requirements, but specific examples include bisphenol A diglycidyl ether type epoxy, bisphenol F diglycidyl ether type epoxy, and bisphenol S
Diglycidyl ether epoxy, 3,3 ', 5,5'-tetramethyl 4,4'-dihydroxybiphenyl diglycidyl ether epoxy, 4,4'-dihydroxybiphenyl diglycidyl ether epoxy, 1,6-dihydroxybiphenyl There are diglycidyl ether type epoxy, phenol novolak type epoxy, bromine type cresol novolak type epoxy, bisphenol D diglycidyl ether type epoxy, glycidyl ether of 1,6 naphthalene diol, triglycidyl ether of aminophenols and the like.
These may be used alone or as a mixture. Further, in order to obtain a liquid sealing material having excellent reliability, it is preferable that the ionic impurities such as Na ⁺ and Cl ⁻ of the epoxy resin are as small as possible.

The aromatic amine curing agent (B) used in the present invention is a liquid at room temperature, and is preferably an alkylated diaminodiphenylmethane. Amines having no aromatic ring are poor in heat resistance and have a fatal drawback of poor storage stability because they are highly reactive even in an atmosphere of zero degree or less, and are not suitable for the present invention. Alkylated diaminodiphenylmethane is preferable because it is easily available, is liquid at room temperature as a property, and does not crystallize even during frozen storage. Examples thereof include ethylated diaminodiphenylmethane, methylated diaminodiphenylmethane and the like.
In addition, in order to obtain a liquid sealing material having excellent reliability, it is preferable that ionic impurities such as Na ⁺ and Cl ⁻ of an amine-based curing agent are as small as possible. The aromatic amine-based curing agent can provide a material having very good fluidity in combination with the liquid epoxy resin. Even when flowing into the package under no pressure and curing, no air bubbles remain, and problems with fluidity such as voids and unfilling hardly occur.

The compounding molar ratio of the epoxy resin as the main component and the aromatic amine-based curing agent as the curing agent is preferably 0.9 to 1.5. When it is less than 0.9, an unreacted amino group remains excessively, which leads to a decrease in moisture resistance and a decrease in reliability. Conversely, if it exceeds 1.5, curing will be insufficient, leading to a decrease in reliability. More preferably in the above mixing ratio 1.1
1.31.3, which means that the epoxy resin is excessive.
This is because imidazole reacts alone with the epoxy resin at the curing temperature.

(C) Examples of the imidazole having a hydroxyl group include 2-phenyl-4,5-dihydroxymethylimidazole and 2-phenyl-4-methyl-5-hydroxymethylimidazole.

As the silica (D), for example, crystalline silica, fused silica and the like are used. The shape generally has a spherical shape, a crushed shape, a flake shape, etc., but the linear expansion coefficient can be reduced by adding more filler, and a spherical inorganic filler is best for improving the effect. The addition amount is desirably 60 wt% to 90 wt% based on the final cured product. 60
When the content is less than wt%, the coefficient of linear expansion of the cured product becomes large, and there is a possibility that the resin may accumulate in the package after curing and crack in the T / C test. On the other hand, if it exceeds 90% by weight, the viscosity of the resulting liquid encapsulating resin composition becomes too high, which is not a practical level.

The flow characteristics such as viscosity can be maximized by adjusting the particle size distribution of the filler. In general, fillers with a broad particle size distribution,
It is known that a filler having a larger particle size tends to have a lower viscosity. However, for the purpose of lowering the viscosity, for example,
Fillers that have only a large particle size of 50 μm or more have a lower viscosity, but a relatively heavy filler sinks during curing, causing so-called filler sedimentation, in which the composition ratio differs between the top and bottom of the cured product. I do. A disadvantage of using a filler having a large particle size is that it does not flow into a narrow gap. As represented by a PPGA type package, there is a tendency for packages to be multi-pin and space-saving, and as an example, the pitch between wires has recently become narrower. In order to allow the liquid sealing material to flow under no pressure and to be formed without any fluidity defects such as voids and unfilled, the particle size of the filler must be reduced. However, when the particle size is reduced, the problem that the fluidity is impaired increases.

Therefore, the average particle diameter of the filler is 3 to 10 μm,
Smaller than that of conventional liquid encapsulation materials, and particle size 30μ
The flowability is not impaired by reducing the particle size to 25% by weight or less in the total filler component of those having m or more. Also one
By setting the particle size distribution to 6-45% by weight of the total filler component and the appropriate amount of fine particles, and adjusting the particle size distribution, it is possible to suppress the sedimentation of the filler, which tends to sink during curing. it can.

The liquid sealing resin composition of the present invention may further contain, if necessary, additives such as a diluent, a pigment, a coupling agent, a flame retardant, a leveling agent, and an antifoaming agent, in addition to the above essential components. You can use it. The liquid sealing material is manufactured by dispersing and kneading each component, additive, and the like with three rolls, and performing a defoaming treatment under vacuum. Since the liquid encapsulating resin composition of the present invention can be cured in a shorter time than conventional resins, it is possible to produce a semiconductor device with good productivity by sealing various semiconductor elements using this resin. Can be. Further, since the characteristics of this resin are the same as those of the conventional resin, a highly reliable semiconductor device similar to the conventional one can be manufactured. As a method for manufacturing a semiconductor device, a conventionally known method can be used.

[0019]

The present invention will be described below with reference to the following examples and comparative examples. <Example 1> Bisphenol F type epoxy resin (equivalent weight 17
0, 3.0 Pa · s @ 25C) 100 parts by weight, ethylated diaminodiphenylmethane (Kayahart AA, Nippon Kayaku Co., equivalent 65) as alkylated diaminodiphenylmethane, 38 parts by weight, 2-phenyl-4 as imidazoles 1.2 parts by weight of 5-dihydroxymethylimidazole, 5 parts by weight of epoxidized polybutadiene rubber as a low stress component, 6 parts by weight of γ-glycidyltrimethoxysilane as an adhesion aid, 350 parts by weight of spherical silica having an average particle diameter of 6 μm and a maximum particle diameter of 50 μm Department,
5 parts by weight of butyl cellosolve acetate as a diluent,
Weigh 1 part by weight of carbon black, and add 3 parts
With this roll, the mixture was dispersed and kneaded and subjected to a defoaming treatment under vacuum to obtain a liquid sealing material. Next, the following tests were performed using the obtained liquid sealing resin composition.

1) Viscosity: 2.5 rpm using an E-type viscometer (@ 25C)
The value measured in was used as a value. 2) Storage property: The resin was stored at 25 ° C.
After 4 hours, the viscosity was measured and the rate of change was examined. 3) Gel time; 0.5 cc of the liquid sealing resin composition was dropped on a hot plate at 170 ° C. and stirred with a stapler to obtain a gel time where the stringing was broken. 4) Adhesion; solder resist (manufactured by Taiyo Ink, PSR4
000AUS05 / CA-40AUS2) The liquid sealing resin composition is applied to the glass-epoxy substrate coated with, and a 6x6 mm chip is mounted from above, cured at 150 ° C for 1 hour, and then cured at 200 ° C.
The sample was placed on a hot plate, and the shear shear strength was measured.

5) Reliability-1, 2; A liquid sealing resin composition is applied to a BGA substrate on which a 15 mm square silicon chip made of a BT substrate is mounted (cavity size: 25 mm × 25 mm × 1 mm).
t), cured at 150 ° C. for 1 hour to prepare a test piece. Next, the following processing is performed to perform an ultrasonic flaw detector (hereinafter, S
AT), the presence or absence of peeling and cracking between the semiconductor chip and the printed board interface was confirmed. PCT processing (1
25 ° C./2.3 atm) for 196 hours or T /
C treatment (-65 ℃ / 30min ← → 150 ℃ / 30min) 100
0 cycles were performed, and in each test, the presence or absence of peeling and cracking between the semiconductor chip and the printed board interface was confirmed by SAT. The number of samples used for the test is 10 each.

6) Reliability-3: Ten test pieces manufactured in reliability 1 described above were subjected to a humidity treatment at 30 ° C. and 60% RH, and then subjected to IR reflow (maximum temperature 240 ° C.).
After the treatment, the presence or absence of peeling and cracking was confirmed by SAT. 7) Filler sedimentation: The composition was cured under the above conditions to prepare a cured product having a thickness of 1 mm, and the section was examined for filler sedimentation by an electron microscope. For the measurement, a value obtained by measuring the distance from the boundary between the layer having a large amount of the resin component and the layer containing the filler to the boundary thereof and the surface of the cured product was used.

Example 2 A liquid sealing resin composition was obtained in the same manner as in Example 1 except that the imidazoles of Example 1 were changed to 2-phenyl-4-methyl-5-hydroxymethylimidazole. Next, the same test as in Example 1 was performed using the obtained liquid sealing resin composition.

Comparative Example 1 A liquid encapsulating resin composition was obtained in the same manner as in Example 1 except that the imidazoles of Example 1 were omitted. Next, the same test as in Example 1 was performed using the obtained liquid sealing resin composition. <Comparative Example 2> A liquid sealing resin composition was obtained in the same manner as in Example 1 except that bisphenol A was used in an amount of 2 parts by weight instead of the imidazoles of Example 1. Next, the same test as in Example 1 was performed using the obtained liquid sealing resin composition. <Comparative Example 3> Instead of the imidazoles of Example 1, 2-
A liquid sealing resin composition was obtained in the same manner as in Example 1 except that phenyl 4-methylimidazole was used in an amount of 0.5 part by weight. Next, the same test as in Example 1 was performed using the obtained liquid sealing resin composition.

Table 1 shows the measurement results.

[Table 1]

[0026]

The liquid encapsulating resin composition of the present invention can shorten the curing time while maintaining the storage stability, and does not cause filler sedimentation in terms of reliability. Can be measured. When a semiconductor element is sealed using such a liquid sealing resin composition, a semiconductor device with high productivity and high reliability can be obtained.

Continued on the front page F-term (reference) 4J002 CD031 CD041 CD051 CD061 CD111 CD121 CD131 DJ018 EN036 EU117 FA018 FA088 FD018 FD146 FD157 GJ02 GQ01 4J036 AA01 AC01 AD01 AD04 AD07 AD08 AD20 AF01 AF06 AF08 AF10 DA05 DC04 DC43 DC10 DC04 CA05 EA02 EB02 EB04 EB06 EB07 EB08 EB09 EB13 EB18 EC14 EC20

Claims (5)

[Claims] 1. An epoxy resin composition comprising: (A) a liquid epoxy resin having an average epoxy group of 2 or more; (B) an aromatic amine-based curing agent which is liquid at room temperature; (C) an imidazole having a hydroxyl group; and (D) silica. The liquid sealing resin composition characterized by the above-mentioned. 2. The liquid sealing resin composition according to claim 1, wherein the aromatic amine curing agent is an alkylated diaminodiphenylmethane. 3. The liquid sealing resin composition according to claim 1, wherein 50% by weight or more of the liquid epoxy resin is a liquid epoxy resin having a viscosity at 25 ° C. of 10 PA · s or less. 4. The liquid epoxy resin according to claim 1, wherein the molar ratio of the liquid epoxy resin to the aromatic amine-based curing agent is in the range of 1.1 to 1.3. Liquid sealing resin composition. 5. A semiconductor device in which a semiconductor element is sealed using the liquid sealing resin composition according to claim 1.