JP5321270B2 - Silicone underfill material for flip chip type semiconductor device and flip chip type semiconductor device using the same - Google Patents

Description

  The present invention relates to an underfill material for a flip chip type semiconductor device and a flip chip type semiconductor device using the underfill material.

  Conventionally, flip chip mounting is known as one of bare chip mounting. Flip chip mounting is a method in which electrodes called bumps having a height of about 10 to 100 μm are joined with a conductive paste or solder. For this reason, the underfill material used for sealing and protecting the flip-chip mounted semiconductor element needs to penetrate into a gap of about several tens of μm due to a bump and the like of the substrate and the semiconductor chip. Conventionally used as an underfill material for flip chip mounting is a liquid epoxy resin composition containing an epoxy resin, a curing agent and an inorganic filler.

  By the way, in power modules that have been developed in recent years, for example, high-brightness LEDs, demands for heat resistance and light resistance have increased, and it has become difficult to meet the demands with conventional general-purpose epoxy resin sealing materials. Therefore, switching from an epoxy resin to a silicone resin having higher reliability in terms of heat resistance and light resistance has been performed. The application of silicone resin to LEDs with high light energy is described in Patent Document 1 (Japanese Patent No. 2927279). Even in a high-brightness LED having a flip chip structure, there is a concern that the conventional underfill material for liquid epoxy flip chip is easily deteriorated by high heat and light in the epoxy resin underfill material, and the lifetime of the device itself is shortened. Yes.

  On the other hand, the silicone resin has a higher linear expansion coefficient and higher elastic modulus than the epoxy resin, and thus is likely to cause problems such as chip lift-up during IR reflow or heat cycle.

Japanese Patent No. 2927279

  Accordingly, an object of the present invention is to provide a silicone underfill material for a flip chip type light emitting semiconductor device, which has excellent heat resistance and light resistance, and has low elasticity while using silicone having a higher linear expansion coefficient than epoxy resin, and the undercoat material. An object of the present invention is to provide a flip chip type light emitting semiconductor device using a fill material.

As a result of diligent research, the present invention is a means for solving the above-described problems.
(A) Thermosetting liquid silicone resin composition: 100 parts by mass (B) Spherical inorganic filler having a particle size of 50 μm or less and an average particle size of 0.5 to 10 μm: A curable silicone composition containing 100 to 400 parts by mass A silicone underfill material for flip chip type light emitting semiconductor devices has been developed in which the cured product has a hardness (type A) at 25 ° C. of 40 or less, a Young's modulus of 2.0 MPa or less, and a linear expansion coefficient of 250 ppm or less.
The present invention also provides a flip chip type light emitting semiconductor device to which the above silicone underfill is applied.

  The silicone underfill material for flip chip type light-emitting semiconductor device of the present invention is superior in heat resistance and light resistance compared to the conventional epoxy resin-based underfill material, and the cured product has low elasticity and is usually a silicone resin-based material. Since the linear expansion coefficient is suppressed to be lower than that of silicone, stress relaxation is excellent. In particular, since the elastic modulus after curing is low, problems such as chip lift-up do not occur even during IR reflow or heat cycle. Therefore, the flip chip type light emitting semiconductor device of the present invention has high reliability.

The silicone underfill material and semiconductor device of the present invention will be described in detail.
<Silicone underfill material>
As described above, the silicone underfill material of the present invention contains (A) a thermosetting liquid silicone resin composition and spherical inorganic fillers having a particle size of 50 μm or less and an average particle size of 0.5 to 10 μm as essential components. It consists of a curable silicone composition.

The silicone underfill material has a cured product obtained by curing,
Hardness measured by a hardness test using a type A durometer as defined in JIS K6249 and JIS K6253 at 25 ° C. (hereinafter referred to as type A hardness): 40 or less
-Young's modulus is 2.0 MPa or less,
-The linear expansion coefficient more than -50 degreeC is 250 ppm or less.

  Furthermore, it is preferable that the type A hardness is 30 or less, the Young's modulus is 1.0 MPa or less, and the linear expansion coefficient at −50 ° C. or more is 220 ppm or less.

  A semiconductor device underfilled with a silicone cured product having such a type A hardness, elastic modulus, and linear expansion coefficient has excellent heat resistance and light resistance compared to an epoxy resin underfill. Furthermore, since the cured product can sufficiently relieve stress compared to the case where any one of type A hardness, elastic modulus, and linear expansion coefficient is used as an underfill material, the silicone resin composition outside the above specific range can be relaxed. The phenomenon that the flip chip is pushed up against IR reflow and heat cycle can be prevented. In addition, after underfill curing, when sealing with an overcoat material using, for example, a molding machine, the underfill material is not extruded from under the chip due to the pressure loss of the overcoat material, and a highly reliable semiconductor A device can be obtained.

It demonstrates for every component of the curable silicone composition which comprises the silicone underfill material of this invention.
-(A) Thermosetting silicone resin composition-
As a silicone resin composition as a thermosetting type of component (A),
(A) Organopolysiloxane containing alkenyl group such as vinyl group and allyl group,
An addition-curable silicone composition comprising (b) an organohydrogenpolysiloxane having a Si—H bond and (c) a hydrosilylation curing catalyst is preferred.

Examples of the components (a), (b) and (c) of the addition-curable silicone composition suitable as the component (A) include the following.
[(A) Alkenyl group-containing organopolysiloxane]
The component (a) in the silicone resin composition of the present invention has at least one aliphatic unsaturated group bonded to a silicon atom such as an alkenyl group such as a vinyl group or an allyl group in one molecule, Is an organopolysiloxane having a phenyl group and a viscosity of 0.1 to 10 Pa.s. Any organopolysiloxane can be used as component (a), but usually the main chain is composed of repeating diorganosiloxane units, and both ends of the molecular chain are triorganosiloxy groups. Blocked, linear organopolysiloxanes are preferably used. From the viewpoint of workability of the composition of the present invention, the viscosity of the component (a) at 23 ° C. is 0.1 to 10 Pa.s. The component (a) can be used alone or in combination of two or more. The aliphatic unsaturated group bonded to the silicon atom of component (a) may be bonded to either the silicon atom at the end of the molecular chain or the silicon atom at the non-terminal end of the molecular chain (in the middle of the molecular chain). Although those having an aliphatic unsaturated group bonded to silicon atoms at both ends of the molecular chain are preferred, the content of the aliphatic unsaturated group is 1 to 1 in one molecule. It is desirable that the number is 10, especially about 1 to 6.

  As a preferable example of the component (a), the following general formula (1):

(1)
Wherein R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, R ² is the same or different unsubstituted or substituted monovalent hydrocarbon group other than phenyl group, and R ³ Is a phenyl group, and L and m are positive integers.)
The organopolysiloxane represented by these is mentioned.

In the general formula (1), R ¹ is, for example, a lower alkyl group such as a methyl group, an ethyl group, a propyl group, or a butyl group; a cycloalkyl group such as a cyclohexyl group; an alkenyl group such as a vinyl group or an allyl group; Aryl groups such as a group, tolyl group and xylyl group; and aralkyl groups such as a benzyl group. Among these, those having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms are preferable.

R ² is, for example, a lower alkyl group such as a methyl group, an ethyl group, a propyl group, or a butyl group; a cycloalkyl group other than a cyclohexyl group such as a cyclopentyl group; an alkenyl group such as a vinyl group or an allyl group; a tolyl group; An aryl group other than a phenyl group such as a xylyl group; an aralkyl group such as a benzyl group; Among these, those having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms are preferable, and a methyl group is particularly preferable.

  Further, L and m are positive integers, and are particularly numbers such that the viscosity of the component (A) at 23 ° C. falls within the above-described range. L and m are preferably integers satisfying 50 <L + m <500, 0.02 <m / (m + L) <0.21, and more preferably satisfying 50 <L + m <300. And an integer satisfying 0.02 <m / (m + L) <0.21, preferably 0.02 <m / (m + L) <0.16.

  Specific examples of the component (a) include, but are not limited to, organopolysiloxanes represented by the following formulas.

[(B) Organohydrogenpolysiloxane]
Component (b), organohydrogenpolysiloxane, acts as a crosslinking agent. Hydrogen atoms bonded to silicon atoms (SiH groups) in the component and aliphatic unsaturated groups bonded to silicon atoms in component (a) (alkenyl groups such as vinyl groups and allyl groups, in particular vinyl groups and / or allyl groups) A cured product is formed from the composition of the present invention by an addition reaction with the group. The molecular structure of this component may be any of linear, branched, cyclic, branched cyclic, and network. The position of the SiH group is not particularly limited, and since the component (a) has a molecular chain end portion, the SiH group may exist only in either the molecular chain end portion or the molecular chain non-terminal portion. , May be present in both. Component (b) can be used alone or in combination of two or more.

As the component (b), for example, the following average composition formula (2):
H _c (R ⁴ ) _d SiO _{(4-cd) / 2} (2)
Wherein R ⁴ is the same or different unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, and c and d are 0.001 ≦ c <2, 0.7 ≦ d ≦ 2 and 0.8 ≦ c + d ≦ 3.)
An organohydrogenpolysiloxane having at least two SiH groups (usually 2 to 300), preferably 3 or more (for example, about 3 to 200, especially about 4 to 100) in one molecule. Can be mentioned.

Here, as R ⁴ in the above formula (2), for example, the same or different unsubstituted or substituted carbon atoms having 1 to 10 carbon atoms containing no aliphatic unsaturated bond, particularly preferably 1 to 7 carbon atoms are used. Specific examples thereof include, as specific examples, groups other than the alkenyl group among the groups exemplified for the substituent R ² of the general formula (1), for example, a lower alkyl group such as a methyl group. And aryl groups such as a phenyl group.

  C and d are numbers satisfying 0.001 ≦ c <2, 0.7 ≦ d ≦ 2, and 0.8 ≦ c + d ≦ 3, preferably 0.05 ≦ c ≦ 1, 0.8 ≦ d ≦ 2 and 1 ≦ c + d ≦ 2.7. The number of silicon atoms in the organohydrogenpolysiloxane of component (b) is usually 2 to 300, preferably 3 to 200, more preferably about 4 to 100.

Specific examples of the component (b) include pentamethyltrihydrogencyclotetrasiloxane, 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, tris (hydrogen Dimethylsiloxy) methylsilane, tris (hydrogendimethylsiloxy) phenylsilane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane / dimethylsiloxane cyclic copolymer, trimethylsiloxy group-blocked methylhydrogenpolysiloxane, trimethylsiloxy at both ends Capped dimethylsiloxane / methylhydrogensiloxane copolymer, dimethylhydrogensiloxy group-capped dimethylpolysiloxane at both ends, dimethylhydrogensiloxy group-capped dimethylsiloxy at both ends Methylhydrogensiloxane copolymer, trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane copolymer, trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane / dimethylsiloxane copolymer, both-end trimethyl Siloxy group-blocked methylhydrogensiloxane / methylphenylsiloxane / dimethylsiloxane copolymer, both ends dimethylhydrogensiloxy group-blocked methylhydrogensiloxane / dimethylsiloxane / diphenylsiloxane copolymer, both ends dimethylhydrogensiloxy group-blocked methylhydro Gensiloxane / dimethylsiloxane / methylphenylsiloxane copolymer, (CH ₃ ) ₂ HSiO _1/2 unit and (CH ₃ ) ₃ SiO _1/2 Copolymer consisting of units and SiO _4/2 units, copolymer consisting of (CH ₃ ) ₂ HSiO _1/2 units and SiO _4/2 units, (CH ₃ ) ₂ HSiO _1/2 units and SiO _{4 And a} copolymer composed of _{/ 2} units and (C ₆ H ₅ ) ₃ SiO _1/2 units.

The component (b) is usually added with chlorosilane such as R ⁴ SiHCl ₂ , (R ⁴ ) ₃ SiCl, (R ⁴ ) ₂ SiCl ₂ , (R ⁴ ) ₂ SiHCl (R ⁵ is as described above). It can be obtained by equilibrating the siloxane obtained by decomposition or hydrolysis.

  The amount of component (b) is an effective amount for curing the composition of the present invention, and in particular, an aliphatic unsaturated bond (alkenyl such as vinyl group or allyl group) bonded to a silicon atom in component (a). Group, in particular vinyl group and / or allyl group), the amount of SiH group in component (b) is preferably 0.1 to 1.5 mol, more preferably 0.3 to 1.2 mol. Even more preferably, the amount is 0.5 to 1.0 mol. When the blending amount is within this range, the curing reaction proceeds sufficiently, a silicone cured product can be easily obtained from the composition of the present invention, and the unreacted SiH groups remaining in the cured product are reduced to a small amount. Since it is suppressed, changes in rubber physical properties over time are unlikely to occur.

[(C) Platinum group metal catalyst]
The component (c) platinum group metal catalyst is blended in order to cause an addition curing reaction in the composition of the present invention, and can be used singly or in combination of two or more. Examples of the component (c) include platinum-based, palladium-based, and rhodium-based materials. From the viewpoint of cost and the like, platinum-based materials such as H ₂ PtCl ₆ · kH ₂ O, K are particularly preferable. ₂ PtCl ₆ , KHPtCl ₆ · kH ₂ O, K ₂ PtCl ₄ , K ₂ PtCl ₄ · kH ₂ O, PtO ₂ · kH ₂ O, PtCl ₄ · kH ₂ O, PtCl ₂ , H ₂ PtCl ₄ · kH ₂ O (In these formulas, k is a positive integer) and the like and complexes thereof with hydrocarbons, alcohols or vinyl group-containing organopolysiloxanes.

  The compounding amount of the component (c) may be an effective amount as a catalyst, and is preferably 0.001 to 100 ppm, especially 0.01 based on the mass of the platinum group metal per total mass of the components (a) to (c). Within the range of ~ 10ppm.

-(B) Spherical inorganic filler-
The filler of the component (B) is a spherical inorganic filler having a particle size of 50 μm or less and an average particle size of 0.5 to 10 μm.

The particle diameter of the spherical inorganic filler is desirably sufficiently small with respect to the flip chip gap width in order to improve the penetration property. Usually, the particle size is 50 μm or less, desirably 25 μm or less, and more desirably 10 μm or less. The average particle size is usually 0.5 μm or more, preferably 1 μm or more, and is usually 10 μm or less, preferably 5 μm or less. In the present invention, the average particle diameter can be determined, for example, as a weight average value (or median diameter) by a laser light diffraction method or the like.
As the spherical inorganic filler, conventionally known various inorganic fillers can be used, for example, fused silica, crystalline silica, alumina, boron nitride, aluminum nitride, silicon nitride, magnesia, magnesium silicate. , Zinc oxide, and the like. These can be used singly or in combination of two or more. Preferred are fused silica, crystalline silica, and mixtures thereof.

  The blending amount of the inorganic filler is preferably as much as possible from the viewpoint of reducing CTE. However, when the amount is too large, the viscosity of the underfill material is increased, and there is a possibility that the penetration of the thin film is lowered. Of course, there are limitations on formulation. Therefore, as a compounding quantity, it is 100-400 mass parts with respect to 100 mass parts of silicone resin composition of (A) component, Preferably it is 200-300 mass parts. If the amount is too small, the expansion coefficient of the cured product of the underfill material increases, which may cause chip lift-up and cracking in IR reflow and heat cycle tests.

-(C) Other optional components-
Examples of other components include a condensation reaction catalyst, an antioxidant, a light stabilizer, an adhesion aid, and the like, and one or more of these can be blended as necessary.

In order to improve the adhesiveness, an adhesion assistant such as an organosilicon compound having a silicon atom-bonded alkoxy group or an organosilicon compound such as organopolysiloxane may be added as an optional component. Examples of such organosilicon compounds include tetramethoxysilane, tetraethoxysilane, dimethyldimethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, phenyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, and vinyl. Alkoxysilane compounds such as trimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane; hydrogen atoms bonded to silicon atoms in one molecule (SiH group), alkenyl groups bonded to silicon atom (e.g., Si-CH = CH ₂ group), (such as a trialkoxysilyl group such as, for example, trimethoxysilyl groups) alkoxysilyl group, an epoxy group (eg Containing at least two, preferably two or three functional groups selected from the group consisting of (glycidoxypropyl group, 3,4-epoxycyclohexylethyl group), usually having 4 to 30 silicon atoms, in particular Is a siloxane compound (organosiloxane oligomer) having a linear structure or a cyclic structure of about 4 to 20. Moreover, the triazine compound which has a trimethoxysilyl group is mentioned.

  Although it is possible to use a solvent for the purpose of lowering the viscosity of the underfill material, there are dangers such as voids in the cured product and residual solvent. It is necessary to pay attention to. Examples of the solvent that can be used include hydrocarbon solvents such as hexane and heptane, low molecular weight silicones such as hexamethyldisiloxane and octamethyltrisiloxane, and the boiling point is 200 ° C. or less, preferably 180 ° C. or less. More preferably, it is 160 ° C. or lower.

-As an underfill material-
The underfill material of the present invention has a viscosity of 3 to 20 Pa.s at 23 ° C. s, preferably 5-15 Pa.s. s. If the viscosity is too high, it becomes difficult to use a dispenser having a small nozzle diameter, and desired ejection cannot be performed. If the viscosity is too low, the underfill material spreads out of the semiconductor chip, and adhesion with the overcoat material may be a problem.

<Flip chip type light emitting semiconductor device>
The flip chip type light emitting semiconductor device of the present invention is an application of the above-described underfill material of the present invention.

  The method for underfill sealing the flip chip type semiconductor device with the underfill material of the present invention is not particularly limited, but, for example, a dispenser capable of precise ejection is considered suitable. In consideration of the resin discharge property, there are methods of heating the resin or discharging while applying a share, especially for those with a small chip area such as LED, those that can perform highly accurate micro discharge, A jet dispenser capable of temperature control is considered effective. When an addition curable silicone resin composition is used as the thermosetting silicone resin composition of component (A), it cures relatively quickly, so care must be taken when heating the discharge part. The discharge part is controlled to 80 ° C. or less, preferably 60 ° C. or less, and the underfill material that has been underfilled is preferably cured by heating within a range of 100 to 180 ° C., and in particular, 120 to 150. It is preferable to heat within the range of ° C.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

(1) The composition of the addition-curable silicone composition used in each of Examples 1 to 3 and Comparative Examples 1 to 3 is as follows.

Example 1:
(A) Component (a-1) 100 parts by mass of an organopolysiloxane having an average composition represented by the following structural formula

Vinyl group content 0.012mol / 100g, phenyl group content 5mol%, viscosity about 1Pa. s
(B-1) 5 parts by mass of methyl hydrogen siloxane having an average composition represented by the following structural formula

SiH group amount 0.002 mol / g, viscosity 0.03 Pa. s
(C) Amount (B) in which the total amount of (A) component is 3 ppm with platinum vinyl complex as Pt amount
Fine powdered silica having a particle size of 25 μm or less and an average particle size of 1.5 μm 100 parts by mass (C) Adhesive aid: 0.5 parts by mass of triazine compound having a trimethoxysilyl group

Example 2:
(A) Component (a-1) 100 mass parts of both ends vinyl siloxane same as what was used in Example 1 (b-2) 0.5 mass part of methyl hydrogen siloxane whose average composition is represented by following structural formula

SiH group content 0.018 mol / g, viscosity 0.02 Pa. s
(C) Amount (B) in which the total amount of (A) component is 3 ppm with platinum vinyl complex as Pt amount
Fine powdered silica having a particle size of 25 μm or less and an average particle size of 1.5 μm 185 parts by mass (C) Adhesive aid: 0.5 part by mass of triazine compound having a trimethoxysilyl group

Example 3:
(A) Component (a-1) 100 parts by mass of both ends vinyl siloxane same as that used in Example 1 (b-2) 0.5 part by mass of methyl hydrogen siloxane same as that used in Example 2 (c) ) (A) The amount of platinum vinyl complex in the entire component becomes 3 ppm as Pt amount. (B) Component powder particle size of 25 μm or less and fine powder silica having an average particle size of 1.5 μm 233 parts by mass (C) Adhesion aid: trimethoxysilyl Triazine compound having a group 0.5 parts by mass

Comparative example 1:
(A) Component (a-1) 100 parts by mass of both ends vinyl siloxane same as that used in Example 1 (b-1) 5 parts by mass of methyl hydrogen siloxane same as that used in Example 1 (c) ( A) Amount of 3 ppm based on platinum vinyl complex in the total component (C) Adhesion aid: Triazine compound having trimethoxysilyl group 0.5 part by mass

Comparative example 2:
(A) Component (a-2) 100 parts by mass of vinylsiloxane having both terminals whose average composition is the following formula

Vinyl group amount 0.02mol / 100g, phenyl group amount 30mol%, viscosity about 8Pa. s
(B-3) Hydrogen siloxane of chemical formula [{H (CH ₃ ) ₂ SiO} ₂ PhSi] ₂ O 2.5 parts by mass (c) Amount of 3 ppm with platinum vinyl complex as Pt amount in the whole component (A) (C) Adhesion aid: 0.5 parts by mass of a triazine compound having a trimethoxysilyl group

Comparative Example 3:
(A) Component (a-3) Silicone resin of average composition formula [ViMeSiO] ₂₀ [(Me) ₂ SiO] ₂₅ [PhSiO _1.5 ] ₅₅ 45 parts by mass (a-2) Both-end vinyl siloxane described in Comparative Example 2 55 parts by mass (b-3) Hydrogen siloxane described in Comparative Example 2 15 parts by mass (c) (A) In the entire component, the amount of platinum vinyl complex as Pt amount is 10 ppm (B) The average particle size is 25 μm or less 120 parts by mass of fine powder silica with a particle size of 1.5 μm

(2) Characteristic evaluation The characteristics of the underfill material comprising the addition-curable silicone resin composition used in each example and each comparative example were measured by the following method, and the results are shown in Table 1.

[viscosity]
Measurement was performed at 23 ° C. using 100 ml of the composition before curing. For the viscosity, a BM viscometer was used.

[hardness]
By heating the composition at 150 ° C. for 2 hours, a sheet having a thickness of more than 6 mm was prepared for hardness measurement. Hardness was measured using a Type A durometer at 25 ° C.

[Young's modulus]
The composition was heated at 150 ° C. for 2 hours to prepare a cured product sheet having a thickness of 1 mm. The Young's modulus of this cured product was measured by an autograph manufactured by SHIMADZU.

[Linear expansion coefficient (CTE)]
The composition was cured at 150 ° C. for 2 hours to obtain a cured product, and the linear expansion coefficient of the cured product was measured by a thermal / stress / strain measuring apparatus (TMA / SS6100) manufactured by SII.

[Die shear strength]
After drying a substrate in which a 2 mm × 2 mm silicon chip was bonded on a silver plating layer with a bump at 120 ° C. for 2 hours, each composition was dropped onto a piece of the device using a precision dispenser. After waiting for 3 minutes and filling underfill under the chip, it was cured by heating at 150 ° C. for 2 hours. After curing, it was passed through an IR reflow furnace three times (peak temperature 260 ° C.), and then a heat cycle test (−40 ° C. to 120 ° C.) was performed 100 cycles. The die shear strength of the silicon chip was measured with a bond tester after the substrate was dried and after the heat cycle test.

[External observation]
As an external observation, the resin spread under the chip when the resin was underfilled (bleed), and after the die shear strength measurement, the resin under the chip was confirmed, and the resin was completely filled under the chip. Confirmed about.

[Penetration test of overcoat resin]
Use a compression molding machine on a substrate on which a silicon chip with an underfill-sealed composition is mounted. Use a compression molding machine to overtype a silicone resin with a cured product with a type A hardness of 80 at 150 ° C for 10 minutes. Coated (molded). After molding, it was cut out and examined for the presence of overcoat resin under the silicon chip.

Claims (3)

(A) It is represented by the following general formula (1), and has an aliphatic unsaturated group in which two or more alkenyl groups are bonded to a silicon atom in one molecule, and has a viscosity at 23 ° C. of 0.1 to 10 Pa.s. An organopolysiloxane containing a phenyl group (a),
Wherein R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, R ² is the same or different unsubstituted or substituted monovalent hydrocarbon group other than phenyl group, and R ³ Is a phenyl group, L and m are positive integers).
Organohydrogenpolysiloxane (b) represented by the following average composition formula (2) and having at least two SiH groups in one molecule: the amount of SiH groups per mole of the alkenyl groups is 0.1 to 1. An amount of 0 mole, and
H _c (R ⁴ ) _d SiO _{(4-cd) / 2} (2)
Wherein R ⁴ is the same or different unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, and c and d are 0.001 ≦ c <2, 0.7 ≦ d ≦ 2 and 0.8 ≦ c + d ≦ 3.)
Platinum group metal catalyst (c): 0.001 to 100 ppm by mass based on the total mass of the above (a) to (c) in terms of platinum group metal
A thermally curable liquid silicone resin composition: 100 parts by weight of (B) particle size 50μm or less, an average particle diameter 0.5~10μm spherical inorganic filler: 100-3 00 parts by curable silicone compositions containing Consists of
A silicone underfill material for flip chip type light emitting semiconductor devices, wherein the cured product has a hardness (type A) at 25 ° C. of 40 or less, a Young's modulus of 2.0 MPa or less, and a linear expansion coefficient of 250 ppm or less.   The viscosity at 23 ° C. is 3 Pa.s. s-20 Pa. The underfill material according to claim 1, which is s.   A flip chip type light emitting semiconductor device to which the underfill material according to claim 1 is applied.