WO2017220137A1

WO2017220137A1 - Curable liquid epoxy resin compositions useful as underfill material for semiconductor devices

Info

Publication number: WO2017220137A1
Application number: PCT/EP2016/064396
Authority: WO
Inventors: Fang-Cheng Lee; Urs Welz-Biermann; Jürgen STEIGER; Marco Yann HEUER; Matthias Naumann
Original assignee: Evonik Degussa GmbH
Current assignee: Evonik Operations GmbH
Priority date: 2016-06-22
Filing date: 2016-06-22
Publication date: 2017-12-28
Anticipated expiration: 2018-12-22
Also published as: TW201815951A

Abstract

The present invention provides a curable liquid epoxy resin composition useful as underfill material for semiconductor devices, which comprises (a) an epoxy resin component, (b) a VQM resin, (c) a curing agent, and (d) a filler having an average particle size of 10 nm to 100 μηη, wherein the VQM resin is a mixture of a QM silica resin and a vinyl functionalized polydimethylsiloxane. The VQM resin can lower the storage modulus of the curable liquid epoxy resin composition after it is cured. And no phase separation is observed between the curable liquid epoxy resin composition or the cured product and the substrate, after it is cured.

Description

Curable Liquid Epoxy Resin Compositions Useful as Underfill Material for

Semiconductor Devices

Field of the invention

The present invention provides a curable liquid epoxy resin composition useful as underfill material for semiconductor devices, especially flip-chip semiconductor devices, where the resin composition comprises (a) an epoxy resin component, (b) a VQM resin, (c) a curing agent, and (d) a filler having an average particle size of 10 nm to 100 μηη, wherein the VQM resin is a mixture of a QM silica resin and a vinyl functionalized polydimethylsiloxane. The VQM resin can lower the storage modulus of the curable liquid epoxy resin composition after it is cured. And no phase separation is observed between the curable liquid epoxy resin composition or the cured product and the substrate, after it is cured.

Background

For the recent years, flip-chip bonding is widely used as a method for mounting semiconductor chips to meet the request for higher density and higher frequency wiring of electronic devices. In flip-chip bonding, the gap between a chip and a substrate is generally sealed with an encapsulant material called underfill. Today's highly integrated chips operating at full load can run at relatively high temperature. The underfill can improve the thermal conductivity of the chips, but the underfill will be heated in this process. Relatively, underfill with high elastic modulus will damage low K substrates since there is much stress accumulated when the underfill is cured at a high temperature. It would be desirable therefore to provide resin compositions useful as underfill material with low elastic modulus, which are compatible for use with low- K substrates and reduce the internal package stresses that could lead to failures.

WO2012/046636 A1 has disclosed a liquid sealing resin composition used as underfill material with low heat-expansion and low elastic modulus at room temperature. This resin composition comprises a liquid epoxy resin, an amine curing agent, an acrylic resin and an inorganic filler. Low elastic modulus is achieved by the addition of the acrylic resin composed of an acrylic copolymer containing a plurality of different monomer components. However, phase separation has been observed after the resin composition is cured, which may result in higher CTE (Coefficient of Thermal Expansion) or failure of devices. Summary of the invention

An object of the present invention is to provide a curable liquid epoxy resin composition, comprising:

(a) a liquid epoxy resin component,

(b) a VQM resin,

(c) a curing agent, and

(d) a filler,

wherein the VQM resin is a mixture of:

b1 ) a QM silica resin where the clusters comprises trihydrocarbyl-SiOi/2- units and the modification consists of methyl groups and vinyl groups, and

b2) a vinyl functionalized polydimethylsiloxane.

The curable liquid epoxy resin composition of the present invention shows low elastic modulus after it is cured.

Besides, no phase separation is observed between the curable liquid epoxy resin composition or the cured product and the substrate, after it is cured.

Another object of the present invention is to provide underfill material comprising the curable liquid epoxy resin composition of the present invention.

A further object of the present invention is to provide a method of encapsulating a semiconductor device with a semiconductor chip, preferably a flip-chip, electrically interconnected with a carrier substrate, comprising steps of:

(a) providing the underfill material of the present invention between the electrically interconnected surfaces of the semiconductor chip and the carrier substrate to form a semiconductor device assembly; and

(b) exposing the semiconductor device assembly to elevated temperature conditions sufficient to cure the underfill material.

Detailed description of the invention

The compositions according to the invention, the method according to the invention comprising the compositions according to the invention are described below by way of example, without the invention being limited to these exemplifying embodiments. References below to ranges, general formulae or classes of compound should be taken to encompass not only the corresponding ranges or groups of compounds that are explicitly mentioned, but also all sub-ranges and sub-groups of compounds that may be obtained by extracting individual values (ranges) or compounds. Where documents are cited in the context of the present description, it is intended that their content fully form part of the disclosure content of the present invention. Where percentages are given below, they are percentages in % by weight unless stated otherwise. In the case of compositions, the percentages, unless stated otherwise, are based on the overall composition. Where average values are reported below, the averages in question are mass averages (weight averages), unless otherwise indicated. Where measurement values are reported below, these measurement values, unless stated otherwise, have been determined under a pressure of 101 325 Pa and at a temperature at 25°C.

The epoxy resin component of the invention may be any of well-known epoxy resins preferably they have at least two epoxy groups per molecule and are liquid at room temperature (25°C).

Preferably the epoxy resin components are selected from the list of novolac type epoxy resins, such as phenol novolac type epoxy resins and cresol novolac type epoxy resins, bisphenol type epoxy resins, such as a bisphenol A type epoxy resins and bisphenol F type epoxy resins, bisphenol AD epoxy resins, aromatic glycidyl amine type epoxy resins, such as Ν,Ν-diglycidyl aniline, Ν,Ν-diglycidyl toluidine, diaminodiphenylmethane type glycidyl amine and aminophenol type glycidyl amine type epoxy resins, hydroquinone type epoxy resins, stilbene type epoxy resins, triphenol methane type epoxy resins, triphenol propane type epoxy resins, alkyl modified triphenol methane type epoxy resins, alkyl triphenol propane type epoxy resins, triazine-nucleus containing epoxy resins, dicyclopentadiene modified phenol type epoxy resins, naphthol type epoxy resins, aralkyl type epoxy resins, such as phenol aralkyl type epoxy resins or naphthol aralkyl type epoxy resin having a naphthalene, phenylene, and/or a biphenylene skeleton, aliphatic series epoxy resins, such as alicyclic epoxy type resins, such as vinylcyclohexene dioxide type epoxy resins.

The epoxy resin components may be used alone or in combination of two or more thereof. Epoxy resins in solid form at room temperature can also be used in combination with the liquid epoxy resins, as long as the mixtures are preferably liquid at room temperature of 25°C.

In a further preferred embodiment of the present invention, the epoxy resin component is one or more selected from bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol AD epoxy resins, and naphthalene epoxy resins, particularly preferably bisphenol A epoxy resins.

Especially preferably the epoxy resin component is liquid at 25°C and has at least two epoxy groups per molecule, more especially preferably the epoxy resin component is liquid at 25°C and is one or more selected from bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol AD epoxy resins, and naphthalene epoxy resins, particularly preferably bisphenol A epoxy resins where each of these bisphenol epxy resins have at least two epoxy groups per molecule.

Although the content of the epoxy resin component is not limited, it is preferable that the epoxy resin component constitutes 5 to 30 wt%, and more preferably 5 to 20 wt%, based on the total weight of the curable liquid epoxy resin composition, for the reactivity, heat resistance, mechanical strength and flowability of the composition during the underfilling process.

The VQM resin is a mixture of a QM silica resin and a vinyl functionalized polydimethylsiloxane.

The QM resin contains silica clusters of condensed ortho-silicate whereas the clusters have preferably an Mw of 5000 to 25000 g/mol, more preferably of 7000 to 20000 g/mol and in particular preferably of 10000 to 15000 g/mol.

The clusters preferably consist of Q-units that are S1O4/2- units and M units that are trihydrocarbyl-SiOi/2- units. Preferably the hydrocarbyl radicals are independently alkyl radicals and/or alkenyl radicals. Preferably the alkyl radicals are selected from methyl, ethyl, propyl, iso-propyl, butyl, pentyl, hexyl and octyl. Preferably the alkenyl radicals are selected from vinyl, allyl, hexenyl and octenyl, preferably the double bond is a terminal double bond. More preferably the M units are trimethylsilyloxy and vinyldimethylsilyloxy groups.

Preferably the VQM resin comprises the clusters in an amount of 15 to 75 wt% based on the mass of the VQM resin. The VQM resins are qualified by their cluster content as being medium filled e.g. containing 15 to 30 wt% clusters and high filled e.g. containing more than 30 up to 75 wt% clusters.

The VQM resin contains 0 to 0.1 wt% of a solvent based on the mass of the VQM resin preferably lower than 0.01 wt% in particular lower than 0.001 wt%.

Solvents in sense of the present invention are organic and inorganic solvents; preferred inorganic solvent is water, preferred organic solvents are aliphatic and aromatic solvents, more preferred aromatic solvents.

The VQM resins of the invention are all clear colorless liquids with a viscosity of 400 mPas to 80,000 mPas. The viscosity is not correlated with the filler degree.

The viscosity can be determined with any method of the art, preferably the viscosity is measured at 25°C and more preferably with a Discovery HR-1 (TA Instruments) with a cone plate geometry.

The VQM resin has a vinyl content of 0.1 to 1 mmol/g, preferably of 0.15 to 0.8 mmol/g and more preferably of 0.2 to 0.7 mmol/g.

The vinyl content can be determined by any method know in the art preferably by determining the iodine number, more preferably the iodine number is measured using DIN 53241 -1 , 1995.

Preferred VQM resins of the invention are a mixture of a QM silica resin where the clusters have a diameter of 0.001 to 1 nm and comprise trihydrocarbyl-SiOi/2- units, and of a vinylfunctionalized polydimethylsiloxane; the modification consists of methyl groups and vinyl groups and the vinylfunctionalized polydimethylsiloxane is an alpha, omega bisvinyl substituted polydimethylsiloxane; the VQM resins comprise the clusters in an amount of 15 to 75 wt% and contains 0 to 0.1 wt% of a solvent selected from water and aromatic solvent both contents based on the mass of the VQM and the VQM resin consist a vinyl content of 0.15 to 0.8 mmol/g.

Preferred VQM resins are commercially available by Evonik Hanse GmbH under the following trademarks: VQM XP1773, VQM XP 3/1603, VQM 803, VQM 806, VQM 807, VQM 809, VQM 881 , VQM 885.

Although the content of the VQM resin is not limited, it is preferable that the VQM resin constitutes 1 to 20 wt%, and more preferably 3 to 10 wt%, based on the total weight of the curable liquid epoxy resin composition, for the balance between modulus and CTE as well as Tg of the composition after it is cured. The curing agent used herein may be any of well-known agents and is not particularly limited. Preferred curing agents are selected from the list of amine compounds, phenol compounds, organic acid anhydrides, and carboxylic acids. Inter alia, aromatic amines, phenol compounds, and organic acid anhydrides are more preferred, particularly preferred are organic acid anhydrides.

From the working standpoint requiring that the liquid epoxy resin composition of the invention properly flow at room temperature, it is desirable to use a curing agent which is liquid at 25°C. When a curing agent which is solid at 25°C is used, it should preferably be dissolved in another curing agent which is liquid at 25°C so that the overall curing agent is liquid.

Preferred organic acid anhydride curing agents includes methyltetrahydrophthalic anhydride (mthpa), cis-1 ,2,3,6-tetrahydrophthalic anhydride (thpa), hexahydro-4- methylphthalic anhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, endo-bicyclo[2.2.2]oct-5-ene-2,3-dicarboxylic anhydride, cyclobutane-1 ,2,3,4- tetracarboxylic dianhydride, benzophenone-3,3',4,4'-tetracarboxylic dianhydride, 4,4'- oxydiphthalic anhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-(4,4'- isopropylidenediphenoxy)bis(phthalic anhydride), trimellitic anhydride, pyromellitic anhydride, benzophenone tricarboxylic anhydride, ethylene glycol bistrimellitate, glycerol tristrimellitate, maleic anhydride, endomethylene tetrahydrophthalic anhydride, methylendomethylene tetrahydrophthalic anhydride, methylbutenyl tetrahydrophthalic anhydride, dodecenyl succinic anhydride, hexahydrophthalic anhydride, succinic anhydride, methylcyclohexene dicarboxylic anhydride, alkylstyrene-maleic anhydride copolymer, chlorendic anhydride, polyazelaic polyanhydride, particularly preferred organic anhydride is hexahydro-4-methylphthalic anhydride.

Although the content of the curing agent is not limited, it is preferable that the curing agent constitutes 5 to 30 wt%, and more preferably 5 to 25 wt%, based on the total weight of the curable liquid epoxy resin composition, for the reactivity, heat resistance, and mechanical strength of the composition.

The filler can be any of well-known fillers having an average particle size of 5 nm to 100 μηη used to reduce the coefficient of expansion of the composition. The filler can be organic or inorganic. Preferred organic fillers are carbon black, graphite, and acrylate beads. More preferred inorganic fillers are selected from the list of clay, kaolin, talcum, mica, silica such as fumed silica and crystalline silica, calcium carbonate, sodium sulfate, magnesium sulfate, barium sulfate, alumina, titanium oxide, silica-titania, boron nitride, aluminum nitride, silicon nitride, magnesia, magnesium silicate, boron nitride. Furthermore preferred fillers are silica fillers. Especially preferred fillers are spherical fumed silica with an average particle size of 0.1 to 10 μηη, preferably 0.1 to 5 μηη. The fillers may be used alone or in admixture.

As used herein, the "average particle size" can be determined by any method of the prior art, preferably the particle size distribution measuring instrument is based on the laser light diffraction method. The "average particle size" is a weight average value D₅o (particle diameter when the cumulative weight reaches 50%, or median diameter) on particle size distribution measurement by the laser light diffraction method.

Preferably the filler have previously been surface treated with coupling agents such as silane coupling agents and titanate coupling agents in order to enhance the bond strength between the resin and the filler. More preferably a surface treated inorganic filler is compounded in the composition.

Preferred coupling agents used herein are silanes including epoxysilanes such as - glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, v- glycidoxypropyltriethoxysilane and 3-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; vinyl silanes such as vinyltriethoxysilane; aminosilanes such as N- β -(aminoethyl)- γ -aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ- aminopropyltrimethoxysilane; and mercaptosilanes such as γ -mercaptosilane. The amount of the coupling agent and the surface treatment technique are not particularly limited.

Particularly preferred fillers are spherical silica particles which have been surface modified with coupling agents selected from the above preferred silanes.

The surface modification ensures the compatibility of the filler materials with the epoxy resin and the flowability of the whole composition. An advantage of the compositions of the inventions is that they show no phase separation.

Preferably the term phase separation is understood as a macroscopical phase separation that means it is detectable optically without the aid of any technical instruments. Preferably, nanoparticle fillers are further added, preferably silica and/or alumina nanoparticles, having an average particle size of 5 to 80 nm, preferably 10 to 50 nm.

The nanoparticle filler preferably are provided in the form of colloidal dispersions, which are clear without any turbidity.

Preferably, the colloidal dispersion has a solid content of 40 to 50 wt%.

More preferably the nanoparticle fillers are colloidal silica nanoparticles having an average particle size of 10 to 50 nm.

Furthermore preferred silica nanoparticles are surface modified as disclosed in US2008/0306203 which is enclosed with its full disclosure herein by reference. Explicitly enclosed are the examples 12, 16, 17, 18 and 21 of the US2008/0306203.

Preferred silica nanoparticles are commercially available from Evonik Hanse GmbH under the following trademarks NANOCRYL®, NANOPOX® and NANOPOL®. More preferred silica nanoparticles are NANOPOX materials, particularly preferred is NANOPOX E 470.

Although the content of the filler of the inventive composition is not limited, it is preferable that the filler constitutes 30 to 80 wt%, and more preferably 40 to 75 wt%, based on the total weight of the curable liquid epoxy resin composition.

The curable liquid epoxy resin composition according to the invention preferably comprises

(a) the liquid epoxy resin component constitutes 5 to 30 wt%, and more preferably 5 to 20 wt%,

(b) the VQM constitutes 1 to 20 wt%, and more preferably 3 to 10 wt%,

(c) the curing agent constitutes 5 to 30 wt%, and more preferably 5 to 25 wt%,

(d) the filler constitutes 30 to 80 wt%, and more preferably 40 to 75 wt%, based on the total weight of the curable liquid epoxy resin composition.

The curable liquid epoxy resin composition of the present invention can optionally comprise a catalyst, a diluter and/or an adhesive promoter.

As the catalyst, many different materials can be used depending upon the temperature at which cure is desired to occur. For instance, to achieve cure at a temperature in the 100 to 180°C range, a variety of materials may be used. For instance, an imidazole or a metal salt such as copper or cobalt acetyl acetonate might be used.

Preferably the catalyst should be present in an amount with the range of about 0.05 to 1 .5 wt%, preferably 0.1 to 1 wt%, based on the total weight of the curable liquid epoxy resin composition.

Diluents can be used to modify the viscosity of resin composition, which is advantageous when the resin composition is used as underfill material applied for flip- chips with smaller gaps.

When a diluent is used, there may be used either a non-reactive diluent or a reactive diluent, and a reactive diluent is preferably used. In the present invention, the reactive diluent means a compound having an epoxy group and having a relatively low viscosity at a normal temperature, which may further have other polymerizable functional group(s) than the epoxy group, including an alkenyl group such as vinyl and allyl; unsaturated carboxylic acid residue such as acryloyl and methacryloyl. Preferred reactive diluents are mentioned a monoepoxide compound such as n-butylglycidyl ether, 2-ethylhexyl glycidyl ether, phenyl gylcidyl ether, cresyl glycidyl ether, p-s- butylphenyl glycidyl ether, styrene oxide and a-pinene oxide; other monoepoxide compound having other functional group(s) such as allyl glycidyl ether, glycidyl methacrylate, glycidyl acrylate and 1 -vinyl-3,4-epoxycyclohexane; a diepoxide compound such as (poly)ethylene glycol diglycidyl ether, (poly)propylene glycol diglycidyl ether, butanediol diglycidyl ether and neopentyl glycol diglycidyl ether; and a triepoxide compound such as trimethylolpropane triglycidyl ether and glycerin triglycidyl ether.

Adhesion promoters can improve the adhesion of the epoxy resin composition both to the substrate and the flip-chip. Preferred adhesion promoters include the above specified silanes used as coupling agents for the surface modification of the fillers.

In a preferred embodiment of the present invention, the curable liquid epoxy resin composition comprises:

(a) 10 to 20 wt% a liquid epoxy resin component,

(b) 4 to 10 wt% a VQM resin,

(c) 15 to 30 wt% a curing agent,

(d) 50 to 65 wt% a spherical fumed silica having an average particle size of 0.1 to (e) 5 to 10 wt% a nano particle size silica having an average particle size of 5 to 80 nm,

(f) 0.1 to 1.5 wt% a catalyst, and

(g) 1 to 3 wt% an adhesion promoter,

based on the total weight of the curable liquid epoxy resin composition.

Examples

The epoxy resin compositions of the examples and the comparative example were prepared by kneading the components with a three-roller mill according to the formulations indicated in Table 1 . The resulted mixture was degassed by using a planetary vacuum mixer, and then was cured at 190°C for 3 hours.

Table 1 : Formulations

Component Ex 1 Ex 2 Comp. Ex 1

Epoxy EXA-850CRP 14.54 14.54 14.54

Resin [g]

Curing Hexahydro-4- 20 20 20

agent [g] methylphthalic anhydride

Catalyst [g] 1 -Cyanoethyl-2-ethyl-4- 0.16 0.16 0.16

methylimidazole

VQM resin VQM 881 7 —

[g] VQM 807 7 —

Filler [g] NANOPOX® E 470 7.53 7.53 7.53

EM-SIO-020 69 69 59

Adhesion Dynasylan® GLYMO 1 .4 1 .4 1 .4

promoter [g]

Filler Contained (% by weight) 59.2% 59.2% 59.4%

EXA-850CRP: Bisphenol A epoxy resin, commercially available from DIC Corporation.

EM-SIO-020: Spherical Silica with an average particle size of 2 μητι, commercially available from Wellion Trading Co., Ltd.

Dynasylan® GLYMO: 3-Glycidyloxypropyltrimethoxysilane, commercially available from Evonik Industries AG.

VQM 881 : high filled, vinyl content 0.68 mmol/g, viscosity 800 mPas (25°C), commercially available from Evonik Hanse GmbH.

VQM 807: medium filled, vinyl content 0.21 mmol/g, viscosity 5,800 mPas (25°C), commercially available from Evonik Hanse GmbH. NANOPOX® E 470: bisphenol A based epoxy resin reinforced with nano silica particles, commercially available from Evonik Hanse GmbH.

No phase separation was observed for all the examples and the comparative example. CTE was measured in a thermal mechanical analyzer (TMA Q400EM from TA Instruments) with compression mode under the following conditions: the system was stabilized at 25°C for 30 min and then the temperature was increased with the ramp of 10°C/min until 200°C, followed by cooling down with the ramp of 10°C/min until 25°C, and finally, the temperature was increased with the ramp of 10°C/min until 200°C.

Tg was determined by the intersection point of the slop line of CTE.

Storage modulus was determined in dynamic mechanical analyzer (DMA Q800 from TA Instruments, single Cantilever Beam) with single cantilever beam under the following conditions: the system was stabilized at 25°C for 30 min and then the temperature was increased with the ramp of 3°C/min until 260°C, and the system vibration frequency was 1 Hz with 5μηι amplitude.

CTE and Tg as well as storage modulus of the examples and the comparative example were tested. and the results are indicated in Table 2.

Table 2

Ex 1 Ex 2 Comp. Ex 1

Tg [°C], TMA 95.31 95.22 95.96

αι [ppm/°C] 33.49 29.83 25.77

a₂ [ppm/°C] 88.57 106.7 105.5

Storage Modulus (30 °C) [GPa] 6.8 5.9 7.7

It can be seen that the storage modulus of the examples is obviously lower than that of the comparative example, while the CTE basically remains in the same level.

Claims

What is claimed is:

1 . A curable liquid epoxy resin composition, comprising:

(a) an epoxy resin component,

(b) a VQM resin,

(c) a curing agent, and

(d) a filler,

wherein the VQM resin is a mixture of:

b1 ) a QM silica resin where the clusters comprises trihydrocarbyl-SiOi/2- units and the modification consists of methyl groups and vinyl groups, preferably of trimethylsilyloxy- and vinyldimethylsilyloxy- groups, and

b2) a vinyl functionalized polydimethylsiloxane, preferably an alpha, omega bisvinyl substituted polydimethylsiloxane.

2. The curable liquid epoxy resin composition according to claim 1 , wherein the epoxy resin component is one or more selected from the group consisting of bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol AD epoxy resins, and naphthalene epoxy resins.

3. The curable liquid epoxy resin composition according to any one of the

preceding claims, wherein the clusters of the VQM resin have an average particle size d_max as measured by means of small-angle neutron scattering (SANS), of 0.0001 to 5 nm, preferably of 0.001 to 1 nm, at a maximum half- width of the distribution curve of 1.5 d_max, and more preferably the VQM resin comprises the clusters in an amount of 15 to 75 wt% based on the mass of the VQM resin.

4. The curable liquid epoxy resin composition according to any one of the

preceding claims, wherein the VQM resin contains 0 to 0.1 wt%, more preferably lower than 0.01 wt%, particularly lower than 0.001 wt% of a solvent, based on the mass of the VQM resin.

5. The curable liquid epoxy resin composition according to any one of the

preceding claims, wherein the VQM resin has a vinyl content of 0.1 to 1 mmol/g, preferably of 0.15 to 0.8 mmol/g and more preferably of 0.2 to 0.7 mmol/g.

6. The curable liquid epoxy resin composition according to any one of the

preceding claims, wherein the VQM resin

is a mixture of a QM silica resin where clusters have a diameter of 0.001 to 1 nm and comprise trihydrocarbyl-SiOi/2- units which are preferably

trimethylsilyloxy and vinyldimethylsilyloxy groups, and of a vinylfunctionalized polydimethylsiloxane, the modification consisting of methyl groups and vinyl groups and the vinyl functionalized polydimethylsiloxane being an alpha, omega bisvinyl substituted polydimethylsiloxane;

comprises the clusters in an amount of 15 to 75 wt% and contains 0 to 0.1 wt% of a solvent selected from water and aromatic solvent both contents based on the mass of the VQM, and

has a vinyl content of 0.15 to 0.8 mmol/g.

7. The curable liquid epoxy resin composition according to any one of the

preceding claims, wherein the curing agent is selected from amine compounds, phenol compounds, acid anhydrides, and carboxylic acids.

8. The curable liquid epoxy resin composition according to any one of the

preceding claims, wherein the filler (d) is a spherical fumed silica having an average particle size of 0.1 to 10 μηι, preferably 0.1 to 5 μηι,

9. The curable liquid epoxy resin composition according to any one of the

preceding claims, wherein the filler (d) is a spherical fumed silica in combination with a nano particle size silica having an average particle size of 5 to 80 nm, preferably 10 to 50 nm.

10. The curable liquid epoxy resin composition according to any one of the

preceding claims, wherein the filler is surface treated.

1 1 . The curable liquid epoxy resin composition according to any one of the

preceding claims, wherein

(a) the liquid epoxy resin component constitutes 5 to 30 wt%, and more

preferably 5 to 20 wt%,

(b) the VQM constitutes 1 to 20 wt%, and more preferably 3 to 10 wt%,

(c) the curing agent constitutes 5 to 30 wt%, and more preferably 5 to 25 wt%,

12. The curable liquid epoxy resin composition according to any one of the

preceding claims, further comprising a catalyst, a diluter and/or an adhesion promoter.

13. The curable liquid epoxy resin composition according to any one of the preceding claims, comprising:

(a) 10 to 20 wt% a liquid epoxy resin component,

(b) 4 to 10 wt% a VQM resin,

(c) 15 to 30 wt% a curing agent,

(d) 50 to 65 wt% a spherical fumed silica having an average particle size of 0.1 to 10 μηη,

(e) 5 to 10 wt% a nano particle size silica having an average particle size of 5 to 80 nm,

(f) 0.1 to 1.5 wt% a catalyst, and

(g) 1 to 3 wt% an adhesion promoter,

based on the total weight of the curable liquid epoxy resin composition.

14. Underfill material, comprising the curable liquid epoxy resin composition

according to any one of the preceding claims.

15. A method of encapsulating a semiconductor device with a semiconductor chip, preferably a flip-chip, electrically interconnected with a carrier substrate, comprising steps of:

(a) providing the underfill material according to claim 13 between the electrically interconnected surfaces of the semiconductor chip and the carrier substrate to form a semiconductor device assembly; and

(b) exposing the semiconductor device assembly to elevated temperature

conditions sufficient to cure underfill material.