JPH1045877A - Liquid sealing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid sealing material useful for producing highly reliable semiconductor packages not causing the generation of peeling and cracks even on pressure cooker tests and thermal shock cycle tests. SOLUTION: This liquid sealing material contains (a) a liquid epoxy resin, (b) an alkylated diaminodiphenylmethane which is an aromatic amine curing agent liquid at the ordinary temperature, (c) a polybutadiene compound having epoxy groups, (d) a silane coupling agent having one or more functional groups selected from the group consisting of an epoxy group, an amino group, a mercapto group, a vinyl group and a methacryl group in the molecule, and (e) an inorganic filler 1 produced from a polysilazane or a metal alkoxide as a starting raw material and (f) an inorganic filler 2 having an average particle diameter of 1-10μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art For example, a liquid sealing material is used for sealing a plastic pin grid array (hereinafter, referred to as PPGA) type or a plastic multi-chip module (hereinafter, referred to as PMCM) type semiconductor. The reliability is not sufficient as compared with the hermetic sealing type, and the spread of the plastic package has been delayed as compared with the dual in-line (hereinafter, referred to as DIP) type. PPG
A. The cause of the decrease in the reliability of PMCM type semiconductors is that unlike liquid transfer molding of DIP type packages, where moisture enters from packaged organic printed wiring boards, liquid sealing material is placed under no pressure in the packages. Bubbles remain in the resin due to inflow and molding, causing cracks when thermal stress is applied.When thermal stress is applied due to the difference in linear expansion coefficient between the resin and semiconductor chip, organic substrate, the interface And the like, which causes peeling of the film and facilitates the invasion of moisture. Also, to match the coefficient of linear expansion with the substrate, the size, shape,
Many studies have been conducted to adjust the content to prevent any mismatch, but separation from the inorganic filler due to the decrease in resin viscosity during curing is inevitable, and furthermore, coupling to the inorganic filler The desired effect could not be achieved even by adding and treating the agent.

[0003]

SUMMARY OF THE INVENTION According to the present invention, defective products are not generated even in accelerated tests such as a pressure cooker test (hereinafter, referred to as PCT) and a thermal cycle test (hereinafter, referred to as T / C), and the reliability of semiconductors is not increased. Provided is a liquid encapsulating material that can significantly improve the performance.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to a thermosetting resin which causes phase separation, which is one of the biggest drawbacks of a type in which a liquid resin and a conventional inorganic filler represented by silica are dispersed and filled. In order to make up for the drawback that the inorganic filler separates from the mixture, not only at the time of mixing and stirring, but also at the time of curing, the starting material which is liquidized and mineralized at the same time as the curing of the resin is a liquid polysilazane, inorganic filler of metal alkoxide. They have found a system completely different from the conventional idea of adding an agent. That is, the present invention relates to a liquid epoxy resin, an aromatic amine-based curing agent which is liquid at room temperature, a polybutadiene compound having an epoxy group, at least one selected from the group consisting of an epoxy group, an amino group, a mercapto group, a vinyl group and a methacryl group. A liquid sealing material comprising an inorganic filler 1 starting from a silane coupling agent having a functional group in the molecule, polysilazane, and metal alkoxide, and an inorganic filler 2 having an average particle size of 1 to 10 μm. Is that the aromatic amine-based curing agent is an alkylated diaminodiphenylmethane, and the inorganic filler 2 has a particle size of 30 μm.
m or more in the total filler component is 20% by weight or less, and those having a particle size of 1 μm or less are 5 to 40% in the total filler component.
It is a liquid encapsulating material in weight%.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The liquid epoxy resin (a) used in the present invention preferably has a viscosity at 25 ° C. of 10 Pa · s or less at 50% by weight or more of its components.
Unless 50% by weight or more of the epoxy resin component is a low-viscosity liquid epoxy of 10 Pa · s or less, the viscosity of the composition becomes high, and when the PPGA or PMCM package is inflow-sealed with a liquid sealing material, bubbles are involved, It is not preferable because a defective filling at a corner end is apt to occur and leads to a decrease in reliability. As a method for measuring the viscosity of the epoxy resin, in the case of a material that is liquid at room temperature, the viscosity is measured at 25 ° C. with an E-type viscometer manufactured by Toki Sangyo Co., Ltd. There are no particular restrictions on the epoxy resin that satisfies this requirement, but specific examples include bisphenol A diglycidyl ether type epoxy resin, bisphenol F diglycidyl ether type epoxy resin, and bisphenol S diglycidyl ether type epoxy resin. Resin, 3,3 ', 5,5'-tetramethyl-
4,4'-dihydroxybiphenyldiglycidyl ether type epoxy resin, 4,4'-dihydroxybiphenyldiglycidyl ether type epoxy resin, 1,6-dihydroxybiphenyldiglycidyl ether type epoxy resin, phenol novolak type epoxy resin, bromine type cresol There are novolak type epoxy resins and bisphenol D diglycidyl ether type epoxy resins. These may be used alone or in combination. In addition, in order to obtain a highly reliable liquid sealing material, Na ^{+ of} epoxy resin,
Cl ^- ionic impurities such as those as small as possible is preferable.

As the aromatic amine-based curing agent (b) used in the present invention, any aromatic amine-based curing agent that is liquid at room temperature can be used, but alkylated diaminodiphenylmethane is particularly preferred. Amines having no aromatic ring are poor in heat resistance and have a fatal drawback of poor preservability because they are highly reactive even in an atmosphere of zero degree or lower, and are not suitable for the present invention. Also, in order to obtain a liquid sealing material with excellent reliability,
Amine curing agent is Na ^+, Cl ^- ionic impurities such as those as small as possible is preferable. The combination of (b) the aromatic amine-based curing agent and (a) the liquid epoxy resin can provide a material having extremely good fluidity.
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. Mixing molar ratio of (a) epoxy resin as a main agent and (b) aromatic amine-based curing agent as a curing agent (a) /
(B) is desirably 0.9 to 1.2. If 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 1.2, curing will be insufficient, leading to a decrease in reliability.

Examples of the elastomer used in the present invention include (a) a polybutadiene compound having an epoxy group, which has good compatibility with an epoxy resin and is expected to have low stress and toughness. Generally, elastomers are
It has a property that the moldability is reduced due to bleeding after injection curing due to lack of compatibility with the epoxy resin. However, the incorporation of an epoxy group into a part of the molecule increases the compatibility, partially reacts with the curing agent (b), and crosslinks, thereby improving the bleeding property and reducing the stress and toughness inherent to polybutadiene having an epoxy group. It is thought that the transformation can also be expressed. The polybutadiene compound having an epoxy group preferably has a number average molecular weight of 1,000 to 2,000. If it is less than 1000, bleeding tends to occur, and if it exceeds 2000, the viscosity becomes high, and both are not preferred. Further, the epoxy content (main chain addition mole fraction%) is preferably 3 to 10%.
If it is less than 3%, the compatibility is poor, and if it exceeds 10%, it crosslinks with the curing agent, so that a so-called sea-island structure cannot be obtained, so that a reduction in stress cannot be expected.

By adjusting the amount of the polybutadiene compound having an epoxy group, low stress and toughness can be maximized. The amount of addition
(C) / {(a) + (b) + (c)} = 0.03-0.
1 is desirable. If it is less than 0.03, the effects of lowering the stress and increasing the toughness cannot be expected, and in particular, surface cracks occur in T / C, leading to poor reliability. On the other hand, if it exceeds 0.1, the compatibility with the epoxy resin (a) deteriorates, oil floats on the package surface, bleeding occurs, and the moldability is reduced. Further, in combination with a random copolymerized silicone-modified epoxy resin, a random copolymerized silicone-modified phenolic resin, or a polyolefin containing an epoxy group, which has a low stress effect and is compatible with (c) a polybutadiene compound having an epoxy group. Is also good.

(D) As a silane coupling agent having at least one functional group selected from the group consisting of an epoxy group, an amino group, a mercapto group, a vinyl group and a methacryl group in a molecule, epoxysilane (for example, Shin-Etsu Chemical Co., Ltd.) Industrial Co., Ltd. KB
M-403) is preferred. If you want to increase the adhesion to the substrate depending on the application, aminosilane,
Mercaptosilane, vinylsilane, and methacrylsilane may be partially or entirely added to the total amount of the coupling agent.

(E) Examples of the inorganic filler 1 include metal alkoxide and polysilazane. Also, a mixture of both may be used. Metal alkoxides include tetramethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, butyltrimethoxysilane Ethoxysilane, tetrapropoxysilane, methyltripropoxysilane,
Ethyltripropoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, dipropyldimethoxysilane, dimethyldiethoxysilane, diethyldiethoxysilane, γ-chloropropyltrimethoxysilane, γ
-Chloropropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyl Examples include tripropoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, tetramethoxytitanium, tetraethoxytitanium, tetrapropoxytitanium, tetrabutoxytitanium, and metal alkoxides containing fluorine in the molecule.

Examples of the polysilazane include polycarbosilazane, hexamethyldisilazane, methylchlorosilazane, polycyclomethylhydridosilazane, oligomethylsilazane, hydridepolysilazane, methylvinyloligosilazane, methylpolydisilazane, phenylvinylpolysilazane, and chloromethyl. Disilazane, polymethylsilazane, polymethylhydrosilazane, polymetallosilazane,
Examples include hexamethylcyclotrisilazane, octamethylcyclotetrasilazane, polytitanosilazane, perhydropolysilazane, organopolysilazane, polyaluminosilazane, polyporosilazane, and polysiloxazane. When forming the inorganic filler 1 using polysilazane or metal alkoxide as a starting material, an acid, a base, or the like can be used as a catalyst. For example, triethylamine, diethylamine, monoethanolamine, diethanolamine, triethanolamine, n-exylamine, n
-Butylamine, di-n-butylamine, tri-n-butylamine, guanidine, piguanine, imidazole,
Amines such as 1,8-diazabicyclo- [5,4,0] -7-undecene, 1,4-diazabicyclo- [2,2,2] -octane, sodium hydroxide, potassium hydroxide, lithium hydroxide; Pyridine, alkalis such as aqueous ammonia, inorganic acids such as phosphoric acid, organic tin compounds such as dibutyltin dilaurate, organic acid salts of metals such as borate, aluminum chelate compounds such as aluminum acetylacetonate, metal alkoxides, Glacial acetic acid, acetic anhydride,
Propionic acid, lower monocarboxylic acids such as propionic anhydride, or anhydrides thereof, oxalic acid, fumaric acid, maleic acid, lower dicarboxylic acids such as succinic acid or anhydrides thereof, organic acids such as trichloroacetic acid, alkalis Metal organic carboxylate and carbonate, perchloric acid, hydrochloric acid, nitric acid,
Lewis acids such as sulfonic acid, paratoluenesulfonic acid, boron trifluoride and its complex with an electric donor, tin tetrachloride, zinc dichloride, iron trichloride, aluminum trichloride, antimony trichloride, titanium tetrachloride, and The complex or the like can be used.

According to the present invention, since a liquid compound can be selected as a filler material, compatibility with the epoxy resin is good, and the filler can be uniformly dispersed in the semiconductor encapsulating material. Further, the filler material can be dispersed in the matrix of the sealing material by a chemical bond due to the reaction with the hydroxyl group in the epoxy resin, so that the effect of preventing phase separation of the inorganic filler is high. In order to form the filler, a curing reaction of the filler may be performed simultaneously with the curing of the epoxy resin, or a part of the starting material of the filler may be reacted with the epoxy resin to be used in advance. If the epoxy resin and a part of the filler material react in advance,
Alcohols, amines generated during the formation reaction of the filler,
Since various free substances such as hydrogen can be removed from the system during dispersion kneading and vacuum degassing, the generation of voids and cracks in semiconductor packaging is advantageously prevented. In addition, it is possible to use reaction conditions, catalysts, and the like suitable for the reaction between the hydroxyl group in the epoxy resin and the raw material for the filler and the formation reaction of the filler described in the preceding section. Since the base point is formed, the filler forming reaction can be performed more efficiently.

(F) As the inorganic filler 2, for example, crystalline silica, fused silica or the like is used. The shape is generally spherical, crushed, flake, etc., but by adding more filler, the linear expansion coefficient can be reduced, and in order to improve the effect, a spherical inorganic filler is used. The best. The best addition amount is 50-80 wt%. If it is less than 50 wt%, the effect of reducing the coefficient of linear expansion is small, and if it exceeds 80 wt%, the viscosity of the liquid resin becomes too high and it is difficult to use it at a practical level. Further, by adjusting the particle size distribution of the filler, it is possible to maximize flow characteristics such as viscosity. It is generally known that a filler having a particle size distribution having a wide distribution range or a filler having a large particle diameter tends to have a lower viscosity. However, for the purpose of lowering the viscosity, for example, 5
Fillers with only a large particle size of 0 μm or more have low viscosity, but the 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. Further, when a filler having a large particle size is used, there is a disadvantage that the filler does not flow into a narrow gap. As represented by a PPGA type package, in recent years, there has been a tendency to increase the number of pins and to save space, and the pitch between wires has become narrower. In such a situation, the particle size of the filler must be reduced 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. However, reducing the particle size also increases the problem that the fluidity is impaired.

Therefore, the average particle size of the filler is 1 to 10 μm.
20% by weight or less of the total filler component, and those having a particle size of 30 μm or more and 5 to 40% of the total filler component have a particle size of 1 μm or less.
By adjusting the particle size so as to be% by weight, the fluidity is not impaired. If the average particle size is less than 1 μm,
The viscosity at the time of molding becomes high and the fluidity is impaired. If it exceeds 10 μm, the reliability of the semiconductor becomes poor. The particle size is 30 μm
If the above content exceeds 20% by weight of the total filler component, the reliability is similarly deteriorated. For particles having a particle size of 1 μm or less, 5 to 40% by weight of the total filler component and an appropriate amount of fine filler are added and the particle size distribution is adjusted to prevent the filler from sinking when the fine filler sinks during curing. Can be suppressed. 1μ
If less than 5% by weight of the total filler component is less than 5% by weight, there is no effect of suppressing the settling of the filler. The particle size distribution and the average particle size in the present invention are measured by a laser method (Horiba, LA-500). The average particle size was the median size.

The liquid sealing material of the present invention contains, in addition to the above-mentioned essential components, other resins and catalysts for accelerating the reaction, a diluent, a pigment, a coupling agent, a flame retardant, and a leveling agent as required. Additives such as antifoaming agents may be used. The liquid sealing material is manufactured by dispersing and kneading the components, additives, and the like with, for example, three rolls and defoaming under vacuum.

[0016]

The present invention will be described with reference to the following examples and comparative examples. <Examples 1 to 4> The following raw materials were dispersed and kneaded at a ratio shown in Table 1 with three rolls, and subjected to defoaming treatment under vacuum to obtain a liquid sealing material. PPG using the obtained liquid sealing material
Package A was sealed and cured in an oven at 165 ° C. for 3 hours to obtain a semiconductor package. The average particle size of the fused silica was 2.5 μm, and the particle size in all the filler components was 30 μm.
m is 12% by weight and those having a particle size of 1 μm or less are 8% by weight.
% By weight.・ Bisphenol F diglycidyl ether type epoxy resin (Epoxy equivalent: 155, 1.6 Pa · s / 25 ° C.) ・ Naphthalene F diglycidyl ether type epoxy resin (Equivalent: 135, 124 Pa · s / 25 ° C.) ・ Alkylated diaminodiphenylmethane curing agent (Amino equivalent 65) ・ Polybutadiene rubber having epoxy group (number average molecular weight 1500, epoxy content 5 mol%) ・ Glycidyltrimethoxysilane ・ Tetraethoxysilane ・ Perhydropolysilazane (PHPN-1 manufactured by Tonen) ・ Triethylamine ・ Fused silica ·Carbon black

<Example 5> First, 60 parts of bisphenol F diglycidyl ether type epoxy resin, 40 parts of naphthalene F diglycidyl ether type epoxy resin, and tetraethoxysilane 1 were prepared in proportions as shown in Example 5-I of Table 1.
After 0 parts by weight and 0.3 parts by weight of triethylamine were previously mixed at 60 ° C. for 5 hours, vacuum degassing was performed. Next, the remaining raw materials were added at the ratios shown in Example 5-II in Table 1, dispersed and kneaded with three rolls, and defoamed under vacuum to obtain a liquid sealing material. Using the obtained liquid sealing material,
The PPGA package was sealed and cured in an oven at 165 ° C. for 3 hours to obtain a semiconductor package. The average particle size of the fused silica was 2.5 μm, and 12% by weight of particles having a particle size of 30 μm or more and 8% by weight of particles having a particle size of 1 μm or less in all the filler components.

<Comparative Example 1> The following raw materials were dispersed and kneaded at the ratios shown in Table 1 with three rolls and subjected to a defoaming treatment under vacuum to obtain a liquid sealing material. Using the obtained liquid sealing material, P
The PGA package was sealed and cured in an oven at 165 ° C. for 3 hours to obtain a semiconductor package.・ Bisphenol F diglycidyl ether type epoxy resin (Epoxy equivalent: 155, 1.6 Pa · s / 25 ° C.) ・ Naphthalene F diglycidyl ether type epoxy resin (Equivalent: 135, 124 Pa · s / 25 ° C.) ・ Alkylated diaminodiphenylmethane ・ Polybutadiene Rubber ・ Glycidyltrimethoxysilane ・ Carbon black ・ Fused silica (average particle size is 2.5μm)

[0019]

[Table 1]

<< Evaluation Method >> Viscosity: The value measured at 2.5 rpm with an E-type viscometer (25 ° C.) was taken as a value. The higher the value, the worse. When the viscosity exceeds 50 Pa · s, workability at the time of dispensing deteriorates. -Thixo ratio: 0.5 rpm and 2.5 rpm with the above viscometer
The ratio of the viscosity in m was taken as the value. -Storage property: Time was taken for the viscosity to be twice the initial viscosity. ○
Is 72 hours or more, Δ is 24-72 hours, and X is 24 hours or less. Curability: Inject a liquid sealing material into PPGA package piece parts, cure at 165 ° C for 3 hours, and count the number of voids on the package surface. And filler separation was observed. The number of voids on the package surface was observed with a microscope, and the number of voids of several μm or more was counted. The unfilled package was observed with an ultrasonic flaw detector (hereinafter referred to as SAT). For the filler separation, the cross section of the package was polished, and the thickness of the resin layer on the surface was measured. Those having a size of 5 μm or more were indicated as having filler separation. The number of evaluated PPGA packages is 10. -Peeling and cracking after curing: before treatment, PCT treatment (1
After 720 hours at 25 ° C / 2.3atm, T / C treatment (-
(65 ° C./30 minutes →→ 150 ° C./30 minutes) After 1000 cycles, SAT was used to confirm the presence or absence of peeling and cracking between the semiconductor chip and the printed circuit board interface. The number of evaluated PPGA packages is 10.

Table 2 shows the evaluation results.

[Table 2]

[0022]

When the semiconductor package is sealed with the liquid sealing material of the present invention, a highly reliable semiconductor without peeling or cracking can be obtained even in a pressure cooker test or a thermal cycle test.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C08K 5/54 NLC C08K 5/54 NLC 7/18 NLD 7/18 NLD C08L 63/00 NJW C08L 63 / 00 NJW H01L 23/29 H01L 23/30 R 23/31

Claims (3)

[Claims] 1. A liquid epoxy resin, (b) an aromatic amine curing agent which is liquid at room temperature, (c) a polybutadiene compound having an epoxy group, (d) an epoxy group, an amino group, a mercapto group, and vinyl. Group, a silane coupling agent having at least one functional group selected from the group of methacrylic groups in the molecule, (e) an inorganic filler 1 starting from polysilazane and metal alkoxide, and (f) an average particle size of 1 to 1.
A liquid sealing material comprising an inorganic filler 2 of 10 μm. 2. The liquid sealing material according to claim 1, wherein the aromatic amine curing agent is an alkylated diaminodiphenylmethane. 3. An inorganic filler 2 having a particle size of 30 μm or more accounts for 20% by weight or less of all the filler components, and a particle size of 1% or less.
3. The liquid encapsulating material according to claim 1, wherein the content of the filler is at most 5 [mu] m to 40% by weight of the total filler component.