JP5532582B2 - Method for sealing flip-chip type semiconductor device, method for selecting chip-on-chip underfill material, and flip-chip type semiconductor device - Google Patents

Description

According to the present invention, as an underfill material for chip-on-chip (hereinafter referred to as “COC”) when sealing a semiconductor device, gap penetration between substrates, elements, etc., and prevention of contamination of the elements are prevented. Method of sealing a flip-chip type semiconductor device using a liquid epoxy resin composition for sealing a semiconductor having a function of (bleed prevention), a method of selecting an underfill material for COC, and a method of sealing Alternatively , the present invention relates to a flip chip type semiconductor device sealed with a COC underfill material selected by the selection method .

As electronic devices become smaller, lighter, and have higher performance, semiconductor mounting methods are also diversifying. One of pin insertion type, surface mounting, and bare chip mounting is flip chip mounting. Flip-chip mounting is a method in which several to several thousand electrodes called bumps having a height of about 10 μm to 100 μm are formed on the wiring pattern surface of an LSI chip, and the electrodes on the substrate are joined with a conductive paste or solder. For this reason, the sealing material used for flip-chip sealing protection needs to penetrate into the gap between the substrate and the LSI chip. Liquid epoxy resin compositions used as conventional flip-chip underfill materials contain an epoxy resin, a curing agent, and an inorganic filler, and have the same linear expansion coefficient as semiconductor chips, substrates, and bumps in order to increase reliability. Therefore, it is necessary to add a large amount of inorganic filler. On the other hand, in the COC structure, generally, lead wires for transmitting signals are projected from the upper periphery of the lower chip toward the substrate, and pads for fixing the lead wires are installed on the upper periphery of the chip. Yes. Furthermore, since this chip is installed at a site where lightness, thinness and smallness are required, it is necessary to make the flip chip and its peripheral elements finer. In addition to being required to penetrate the gap, it is necessary to prevent bleeding to peripheral elements such as pads for connecting lead wires after underfill.
However, there is a situation in which a liquid epoxy resin composition having such a gap penetration property and a function of preventing bleeding does not exist as an underfill material for COC.

In addition, the following are mentioned as prior art documents relevant to the present invention.
JP 2001-200199 A Japanese Patent Laid-Open No. 2001-354751

The present invention has been made in view of the above circumstances, and as a COC underfill material when sealing a semiconductor device, functions of interstitial space between substrates, elements, etc. and prevention of contamination (bleeding prevention) of the elements. A method for encapsulating a flip chip type semiconductor device using a liquid epoxy resin composition for encapsulating a semiconductor, a method for selecting an underfill material for COC, and a method for encapsulating or selecting by the method for selecting It is an object of the present invention to provide a flip chip type semiconductor device sealed with a COC underfill material .

As a result of intensive studies to achieve the above object, the present inventor has (A) a naphthalene type epoxy resin, (B) an acid anhydride curing agent: with respect to 1 mol of the epoxy group in the component (A). An amount of 0.3 to 0.7 mol, (C) a spherical silica powder having an average particle diameter of 0.3 to 0.8 μm: 20 to 60 with respect to the total amount of the components (A) to (C) A liquid epoxy resin composition containing an amount of mass% and having an average particle diameter of the component (C) of 1/10 or less with respect to the gap dimension between the substrate and the element of the semiconductor device is chip-on- a method in which for sealing the flip chip type semiconductor device is used as an underfill material for chips, found to be a chromatic, the present invention has been accomplished.

Accordingly, the present invention provides a method for sealing a flip-chip type semiconductor device using the liquid epoxy resin composition for semiconductor sealing shown below as a COC underfill material, a method for selecting a COC underfill material, Provided is a flip-chip type semiconductor device sealed with a COC underfill material selected by the sealing method or the selection method.
Claim 1:
(A) Naphthalene type liquid epoxy resin,
(B) Acid anhydride curing agent: an amount of 0.3 to 0.7 mol relative to 1 mol of the epoxy group in the component (A),
(C) Spherical silica powder having an average particle diameter of 0.3 to 0.8 μm: containing an amount of 20 to 60% by mass with respect to the total amount of the components (A) to (C), and ( C) The liquid epoxy resin composition having an average particle size of the component of 1/10 or less with respect to the gap size between the substrate and the element of the semiconductor device ,
(I) When the initial state is from immediately after being produced at room temperature (23 to 25 ° C.) to after 100 hours, the initial viscosity is 20 Pa · s or less,
(Ii) an intrusion time from the end of the two-ply glass plate having a 10 μm gap heated to 120 ° C. to a depth of 10 mm is 60 seconds or less, and
(Iii) 3 mg is dropped on the mirror surface of Si placed in an atmosphere of 120 ° C., and the diameter in a state where the spread has stopped, that is, the average value of the minor axis and the major axis is 5 mm or less.
A method of encapsulating a flip-chip type semiconductor device using a material that satisfies the above characteristics as an underfill material for chip-on-chip.
Claim 2:
(A) Naphthalene type liquid epoxy resin,
(B) Acid anhydride curing agent: an amount of 0.3 to 0.7 mol relative to 1 mol of the epoxy group in the component (A),
(C) Spherical silica powder having an average particle diameter of 0.3 to 0.8 μm: containing an amount of 20 to 60% by mass with respect to the total amount of the components (A) to (C), and ( In the liquid epoxy resin composition in which the average particle diameter of the component (C) is 1/10 or less with respect to the gap dimension between the substrate and the element of the semiconductor device,
( I ) When the initial state is from immediately after being produced at room temperature (23 to 25 ° C.) to after 100 hours, the initial viscosity is 20 Pa · s or less,
( Ii ) The intrusion time from the edge of the two-ply glass plate having a 10 μm gap heated to 120 ° C. to the depth of 10 mm is 60 seconds or less, and ( iii ) is placed in an atmosphere at 120 ° C. 3 mg was dropped on the mirror surface of Si, and the diameter when the spread stopped, that is, the one satisfying the characteristic that the average value of the minor axis and the major axis was 5 mm or less was selected as the sealing material of the flip-chip type semiconductor device. A method for selecting an underfill material for chip-on-chip.
Claim 3:
A flip chip type semiconductor device sealed by the method according to claim 1.
Claim 4:
A flip-chip type semiconductor device sealed with a chip-on-chip underfill material selected by the method according to claim 2.

According to the present invention, when sealing a semiconductor device, as an underfill material for COC, there is provided a semiconductor sealing having both a function of entering a gap between a substrate and an element and preventing contamination (bleeding prevention) of the element. Method for sealing flip-chip type semiconductor device using liquid epoxy resin composition for use, method for selecting underfill material for COC, and method for sealing or underfill material for COC selected by the selection method It is possible to provide a flip-chip type semiconductor device sealed with .

Hereinafter, the present invention will be described in more detail.
The liquid epoxy resin composition of the present invention contains (A) a liquid epoxy resin, (B) a curing agent, and (C) a spherical silica powder as essential components.
(A) Liquid epoxy resin The liquid epoxy resin may be any liquid epoxy resin that has two or more epoxy groups per molecule and is liquid at room temperature (20 to 30 ° C.). .
For example, bisphenol A type epoxy resin, bisphenol AD type epoxy resin, bisphenol F type epoxy resin, naphthalene type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, biphenyl type epoxy resin, glycidylamine type epoxy resin, alicyclic Examples of the epoxy resin include epoxy resin, cyclopentadiene type epoxy resin, and dicyclopentadiene type epoxy resin.
In particular, it is preferable to use a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol AD type epoxy resin, or a naphthalene type epoxy resin having excellent heat resistance and moisture resistance.

Moreover, the epoxy resin of the following structure can also be used.

Such an epoxy resin contains a small amount of epichlorohydrin-derived chlorine used in the synthesis process, but the total chlorine content in the epoxy resin needs to be 1500 ppm or less, desirably 1000 ppm or less. Moreover, it is preferable that the extraction water chlorine in 20 hours in 100 degreeC and a 50% epoxy resin density | concentration is 10 ppm or less. This is because if the total chlorine content exceeds 1500 ppm and the extracted chlorine exceeds 10 ppm, the reliability of the semiconductor element, particularly the moisture resistance, is adversely affected.
The said liquid epoxy resin can be used individually by 1 type or in combination of 2 or more types.

(B) As the curing agent curing agent, generally known curing agents can be used.
Examples include aromatic amine compounds, phenol compounds, acid anhydrides, and carboxylic acids.
In particular, aromatic amines, phenolic compounds, and acid anhydrides are preferably used from the viewpoint of adhesion and reliability in environmental resistance tests.
These may be used singly or in combination of two or more, but when two or more are mixed, it is preferable to use an acidic substance and a basic substance in consideration of deterioration of storage stability. Absent.
When a phenol compound or acid anhydride is used as the curing agent, the epoxy resin composition of the present invention needs to have an appropriate fluidity at room temperature from the viewpoint of workability, and the curing agent is liquid at 25 ° C. In the case of using a solid curing agent at 25 ° C., it is desirable to dissolve in a liquid curing agent at 25 ° C. and to make the entire curing agent liquid.

  Specific examples of the aromatic amine compound as a curing agent include 3,3′-diethyl-4,4′-diaminophenylmethane, 3,3 ′, 5,5′-tetramethyl-4,4′-diamino. Phenylmethane, 3,3 ′, 5,5′-tetraethyl-4,4′-diaminophenylmethane, 2,4-diaminotoluene, 1,4-diaminobenzene, 1,3-diaminobenzene and the like are preferably used. . When such an aromatic amine compound is used as a curing agent, 0.7 to 1.2 mol, particularly 0.85 to 1.05 mol of aromatic amine per mol of epoxy group in the epoxy resin. It is desirable to blend a system compound. If the blending amount is less than 0.7 mol, the curability may be insufficient, and if it exceeds 1.2 mol, the pot life may be shortened.

  Specific examples of the phenolic compound as the curing agent include novolak type phenol resins such as phenol novolak resin and cresol novolak resin; Bisphenol type phenolic resin such as bisphenol A type resin and bisphenol F type resin; phenolic resin such as biphenyl type phenolic resin, resol type phenolic resin, phenol aralkyl type resin, biphenyl aralkyl type resin; triphenolmethane type resin, triphenolpropane type Triphenolalkane type resins such as resins and phenolic resins such as polymers thereof; naphthalene ring-containing phenolic resins, dicyclopentadiene-modified phenols Butter, and the like are preferably used. When such a phenolic compound is used as a curing agent, 0.8 to 1.2 mol, especially 0.9 to 1.1 mol of phenolic compound is added to 1 mol of epoxy group in the epoxy resin. If the amount is less than 0.8 mol, the curability may be insufficient, and if it exceeds 1.2 mol, the pot life may be shortened.

  As specific examples of the acid anhydride as the curing agent, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyl hymix anhydride and the like are preferably used. When such an acid anhydride is used as a curing agent, 0.3 to 0.7 mol, particularly 0.4 to 0.6 mol of acid anhydride is blended with respect to 1 mol of the epoxy group in the epoxy resin. Desirably, if the blending amount is less than 0.3 mol, the curability may be insufficient, and if it exceeds 0.7 mol, unreacted acid anhydride may remain and the glass transition temperature may be lowered. is there.

  Further, as a curing accelerator when an acid anhydride is used as a curing agent, 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-methylimidazole, 2-phenyl-4,5-dihydroxy Imidazole derivatives such as methylimidazole can be blended, but in order to maintain the high fluidity (gap penetration property), which is also the object of the present invention, it is necessary to have the potential. For this reason, it is desirable to use what was designed so that a hardening accelerator may be coat | covered with a microcapsule etc. and it may react at predetermined temperature.

  These imidazole derivatives can be used as curing accelerators for acid anhydride curing agents as well as curing agents for epoxy resins, but when used as curing accelerators, the total amount of epoxy resin and curing agent It is preferable to add in the range of 1 to 10 parts by mass, particularly 2 to 5 parts by mass with respect to 100 parts by mass. If the addition amount is less than 1 part by mass, bleeding associated with a decrease in reactivity may occur, and if it exceeds 10 parts by mass, the curability is excellent but the storage stability tends to be reduced.

  In addition to the above, carboxylic acid hydrazides such as dicyandiamide, adipic hydrazide, and isophthalic hydrazide can also be used as the curing agent. When such a carboxylic acid hydrazide is used as a curing agent, 0.3 to 0.7 mol, especially 0.4 to 0.6 mol of carboxylic acid hydrazide is added to 1 mol of epoxy group in the epoxy resin. If the blending amount is less than 0.3 mol, the curability may be insufficient, and if it exceeds 0.7 mol, the pot life may be shortened.

(C) Spherical silica powder As the spherical silica powder, those having an average particle diameter of 0.1 to 1.0 μm, particularly 0.3 to 0.8 μm can be used. The average particle size can be measured by a centrifugal sedimentation method, a laser diffraction method, or the like.
Here, if the average particle size is less than 0.1 μm, the surface area of the filler increases, so that the fluidity is lowered and the composition becomes undesirably too viscous. On the other hand, when the thickness exceeds 1.0 μm, the composition tends to hardly enter a flip chip type semiconductor device having a gap of about 10 μm.

  The spherical silica powder is preferably contained in an amount of 20 to 60% by mass, particularly 30 to 50% by mass, based on the total amount of the components (A) to (C). If it is less than 20% by mass, the coefficient of expansion is large, and cracking is induced in the thermal shock test. If it exceeds 60% by mass, the viscosity becomes too high and the fluidity as an underfill material decreases, so that the thin film penetration property is reduced. Bring about a decline.

The composition of the present invention is injected into a gap between a substrate and an element of a semiconductor device using a capillary phenomenon as an underfill material, and the fluidity (penetration) into the gap and sedimentation of spherical silica powder. In order to prevent this, the maximum particle size is designed to be 1/2 or less and the average particle size is 1/10 or less with respect to the gap size.
Here, when the maximum particle size and the average particle size exceed the above dimensions, voids are generated due to a decrease in fluidity, or a layer with less spherical silica powder is formed near the semiconductor chip interface due to sedimentation of the spherical silica powder. , The thermal expansion coefficient of the portion is increased, resulting in a problem that reliability is lowered. Therefore, the average particle size of the spherical silica is 0.1 to 1.0 μm, preferably 0.3 to 0.8 μm.

The spherical silica powder is preferably blended in advance with a surface treatment with a coupling agent such as a silane coupling agent or a titanate coupling agent in order to increase the bond strength with the resin component.
As such a coupling agent, epoxy silane such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N Silane cups such as amino silanes such as -β (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and mercaptosilane such as γ-mercaptosilane It is preferable to use a ring agent.
Examples of commercially available silane coupling agents include KBM403 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.).
Further, a surface treatment agent such as hexamethyldisilazane or tetraethoxysilane may be used, and the surface treatment agent hydrophobizes the surface of the spherical silica powder and exhibits an effect of improving the wettability with the resin component. .
Here, the amount of the coupling agent and the like used for the surface treatment and the surface treatment method are not particularly limited.

Other Additives The composition of the present invention may contain silicone rubber, silicone oil, liquid polybutadiene rubber, or the like for the purpose of reducing the stress of the cured product.
Moreover, you may mix | blend pigments, such as carbon black, dye, antioxidant, another additive, etc. as needed.
The blending amount of these additives is not particularly limited as long as it does not impair the object of the present invention.

The composition of the present invention comprises the above liquid epoxy resin, curing agent, spherical silica powder, and other additives as necessary, while simultaneously or separately, as necessary, while stirring, dissolving, mixing, It can be obtained by dispersing.
Although these stirring apparatuses are not particularly limited, a laika machine equipped with a stirring and heating apparatus, a three roll, a ball mill, a planetary mixer, and the like can be used. Moreover, you may use combining these apparatuses suitably.

The gap penetration function of the obtained composition can be expressed by the viscosity of the composition and the gap penetration time, but the initial viscosity at room temperature (23 to 25 ° C.) is 20 Pa.s. s or less 1 Pa. s or more, more preferably 15 Pa. s or less 1 Pa. s or more, and the intrusion time from the end of the two-layer glass plate having a 10 μm gap heated to 120 ° C. to the depth of 10 mm is 60 seconds or less, 10 seconds or more, more preferably 40 seconds or less It needs to be 10 seconds or more.
Here, the viscosity is 20 Pa. If it exceeds s and the gap penetration time exceeds 60 seconds, the gap penetration amount cannot be ensured with respect to the coating amount, and creeping into the chip occurs. The viscosity is 1 Pa. If it is less than s and the gap penetration time is less than 10 seconds, entrainment voids are likely to occur.
In order to obtain such a gap penetration function, it is necessary to leave at room temperature (23 to 25 ° C.) for about 100 hours in order to improve the wettability of the filler to the resin while ensuring the viscosity. There is.
Here, the initial term refers to a state immediately after the composition of the present invention is produced at room temperature (23 to 25 ° C.) to after 100 hours, and the viscosity is a single cylindrical rotational viscometer, It can be measured using any viscometer such as a double-axis cylindrical viscometer, a cone plate type (cone plate type) viscometer, or a rheometer. It is preferable to measure using a mold rotational viscometer.
The 10 μm gap can be formed by sandwiching an arbitrary spacer such as a pair of double-sided tapes having a thickness of 10 μm between two stacked glass plates, but the pair of spacers is sufficiently spaced ( 5 to 10 mm), the influence of the surface free energy on the spacer end face can be substantially eliminated, and only the influence of the surface free energy on the glass face can be achieved. The glass plate is baked at 600 ° C. for 1 hour and wiped off with acetone, and always has the same surface free energy.

In addition, the function of preventing contamination of the peripheral elements of the composition (prevention of bleeding) can be expressed by the curing speed and droplet diameter of the composition, but the time for the viscosity behavior at 120 ° C. to reach 10 times the initial time is reached. It is 30 to 100 seconds, more preferably 50 to 90 seconds, and 3 mg is dropped on the mirror surface of Si placed in an atmosphere of 120 ° C., and the diameters in the state where the spread stops, that is, the short diameter and the long diameter The average value needs to be 5 mm or less and 2 mm or more.
Here, if the time for the viscosity behavior at 120 ° C. holding to reach 10 times the initial time is less than 30 seconds, it will prevent bleeding, but the intrusion into the gap will be inferior, and creeping into the chip will occur, If it exceeds 100 seconds, the fluidity after intrusion is large, which may cause bleeding. Moreover, when 3 mg is dripped on the mirror surface of Si placed in an atmosphere of 120 ° C. and the diameter in a state where the spread has stopped exceeds 5 mm, the fluidity after intrusion is large, which causes bleed. If it is less than 2 mm, it is evidence that thixotropy has occurred, that is, fluidity is impaired.
In order to obtain such a function of preventing contamination (preventing bleeding), it is necessary to shorten the gelation time at a predetermined temperature without impairing the gap penetration.
In addition, the initial stage here refers to a state from immediately after the composition of the present invention is produced at room temperature (23 to 25 ° C.) to 100 hours later, and the viscosity is any viscometer as described above. Alternatively, although it can be measured using a rheometer, it is preferably measured using a rheometer in order to measure the viscosity behavior at 120 ° C. in a constant temperature bath.
The Si mirror surface is obtained by mirror-polishing the surface of a Si single crystal substrate. Such a surface generally has a large surface free energy, and usually has the same surface free energy.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to the following examples.

The materials used in the examples and comparative examples are as follows.
(A) Liquid epoxy resin Epoxy resin a: Naphthalene type epoxy resin
(Manufactured by DIC Corporation, HP-4032D)
Epoxy resin b: trifunctional epoxy resin represented by the following formula
(Japan Epoxy Resin Co., Ltd., Epicoat 630LSD)

（Ｂ）硬化剤
硬化剤ａ：メチルテトラヒドロ無水フタル酸、ヘキサヒドロ無水フタル酸の混合物
（新日本理化（株）製、ＭＨ−７００）
硬化剤ｂ：ジエチルジアミノジフェニルメタン
（日本化薬（株）製、カヤハードＡ−Ａ）
硬化剤ｃ：ジエチルトルエンジアミン
（アルベール・コーポレーション（株）製、ＥＴＨＡＣＵＲＥ１００）

(B) Curing agent Curing agent a: Mixture of methyltetrahydrophthalic anhydride and hexahydrophthalic anhydride (manufactured by Shin Nippon Rika Co., Ltd., MH-700)
Curing agent b: diethyldiaminodiphenylmethane
(Nippon Kayaku Co., Ltd., Kayahard AA)
Curing agent c: diethyltoluenediamine
(Albert Corporation, ETHACURE100)

(C) Spherical silica powder Spherical silica a: Spherical silica having an average particle diameter of 0.6 μm
(SE2030-SEE, manufactured by Admatechs)
Spherical silica b: Spherical silica with an average particle diameter of 7 μm
(Manufactured by Tatsumori, TSS-AH)

(D) Other additives Coupling agent: [gamma] -glycidoxypropyltrimethoxysilane
(Shin-Etsu Chemical Co., Ltd., KBM-403)
Curing accelerator: NOVACURE HX-3741
(Asahi Kasei Chemicals)

[Examples 1 and 2 and Comparative Examples 1 to 5]
(A) Liquid epoxy resin, (B) curing agent, (C) silane coupling agent, and (D) spherical silica were blended based on Table 1 and uniformly kneaded to obtain various epoxy resin compositions. .
The viscosity at 25 ° C. of the various epoxy resin compositions obtained was 20-70% when measuring various epoxy resin compositions with a cone plate type E-type viscometer manufactured by Brookfield Co. Measured at the number of rotations entering. The gelation time was measured by measuring the viscosity behavior at 120 ° C. with a rheology MR-300 manufactured by Rheology, and measuring the time when the viscosity reached 10 times. The intrusion property is the time required to reach 10 mm from the end of a glass plate with a 10 μm gap (width 10 mm) placed on a hot plate and heated to 120 ° C. It was measured. In addition, the glass plate used what was baked at 600 degreeC for 1 hour, and wiped off with acetone. In addition, 3 mg of various epoxy resin compositions were dropped on a mirror surface of Si, and the diameter in a state where the spread stopped in an atmosphere of 120 ° C., that is, the average value of the minor axis and the major axis was calculated.
Subsequently, using the various epoxy resin compositions controlled as described above, the following simple devices were evaluated for penetration into the following devices, contamination prevention (bleed prevention), and the presence or absence of chip cracks by a thermal shock test. The results are also shown in Table 1.
(I) Fabrication of Simple Device 1 As shown in FIG. 1, a pair of dimensions is placed on a Si plate 2 having a dimension of 35 mm (l) × 35 mm (w) × 0.7 mm (t) with its mirror surface facing up. 30 mm (l) × 5 mm (w) × 70 μm (t) double-sided tape (manufactured by Nitto) 4 is installed at an interval of 20 mm, and further dimensions 30 mm (l) × 30 mm (w) × 0.7 mm (t A simple device 1 having a gap of 70 μm (h) × 20 mm (w) was produced by superimposing the Si plate 3 of) on the mirror surface.
(Ii) Evaluation of penetration and antifouling properties The various epoxy resin compositions are allowed to enter the simple device 1 from the end of the gap under the condition of 120 ° C. and cured under the condition of 150 ° C./1 hour. Thus, the invasion property and the contamination prevention property were evaluated.
Penetration property: Time from extruding from the gap end to exuding from the opposite gap end is good in less than 100 seconds ○
100 or more, less than 200 seconds △
Inferior after 200 seconds ×
Pollution prevention:
Good if it does not reach the end face of the lower Si plate 3 ○
Good if it stops at the end face of the lower Si plate 3
If it hangs down from the lower Si plate 3 ×
(Iii) Evaluation of chip cracks Si plates 2, 3 which were subjected to a thermal shock test of -55 to 125 ° C and 500 cycles based on JIS C0025 on the simple device (cured) 1 of (ii) above and assumed as a chip The crack was evaluated.

It is a schematic perspective view of the simple device used in order to demonstrate the liquid epoxy resin composition for semiconductor sealing of this invention.

Explanation of symbols

1 Simplified device 2 Substrate 3 Si plate 4 Double-sided tape

Claims (4)

(A) Naphthalene type liquid epoxy resin,
(B) Acid anhydride curing agent: an amount of 0.3 to 0.7 mol relative to 1 mol of the epoxy group in the component (A),
(C) Spherical silica powder having an average particle diameter of 0.3 to 0.8 μm: containing an amount of 20 to 60% by mass with respect to the total amount of the components (A) to (C), and ( C) The liquid epoxy resin composition having an average particle size of the component of 1/10 or less with respect to the gap size between the substrate and the element of the semiconductor device ,
(I) When the initial state is from immediately after being produced at room temperature (23 to 25 ° C.) to after 100 hours, the initial viscosity is 20 Pa · s or less,
(Ii) an intrusion time from the end of the two-ply glass plate having a 10 μm gap heated to 120 ° C. to a depth of 10 mm is 60 seconds or less, and
(Iii) 3 mg is dropped on the mirror surface of Si placed in an atmosphere of 120 ° C., and the diameter in a state where the spread has stopped, that is, the average value of the minor axis and the major axis is 5 mm or less.
A method of encapsulating a flip-chip type semiconductor device using a material that satisfies the above characteristics as an underfill material for chip-on-chip. (A) Naphthalene type liquid epoxy resin,
(B) Acid anhydride curing agent: an amount of 0.3 to 0.7 mol relative to 1 mol of the epoxy group in the component (A),
(C) Spherical silica powder having an average particle diameter of 0.3 to 0.8 μm: containing an amount of 20 to 60% by mass with respect to the total amount of the components (A) to (C), and ( In the liquid epoxy resin composition in which the average particle diameter of the component (C) is 1/10 or less with respect to the gap dimension between the substrate and the element of the semiconductor device,
( I ) When the initial state is from immediately after being produced at room temperature (23 to 25 ° C.) to after 100 hours, the initial viscosity is 20 Pa · s or less,
( Ii ) The intrusion time from the edge of the two-ply glass plate having a 10 μm gap heated to 120 ° C. to the depth of 10 mm is 60 seconds or less, and ( iii ) is placed in an atmosphere at 120 ° C. 3 mg was dropped on the mirror surface of Si, and the diameter when the spread stopped, that is, the one satisfying the characteristic that the average value of the minor axis and the major axis was 5 mm or less was selected as the sealing material of the flip-chip type semiconductor device. A method for selecting an underfill material for chip-on-chip.   A flip chip type semiconductor device sealed by the method according to claim 1.   A flip-chip type semiconductor device sealed with a chip-on-chip underfill material selected by the method according to claim 2.

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