CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to and all the benefits of Japanese Patent Application No. 2020-079564 filed Apr. 28, 2020 and Japanese Patent Application No. 2019-139794 filed on Jul. 30, 2019, which are both hereby expressly incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a curable silicone composition; more specifically, it relates to a curable silicone composition to be used for encapsulating, coating or adhering an optical semiconductor element. The present invention also relates to an encapsulant comprising this curable silicone composition, and to an optical semiconductor element containing said encapsulant. The present invention also relates to a film obtained by solidifying a curable silicone composition.

BACKGROUND TECHNOLOGY

When curable silicone compositions are cured, they form cured products having excellent heat resistance, cold resistance, electrical insulation, weather resistance, water repellency, and transparency, and so they are used in a wide range of industrial fields. Specifically, compared to other organic materials, these cured products are less prone to discoloration and their physical properties deteriorate less, and so they are suitable for optical materials.

For example, patent documents 1-3 describe resin compositions for optical semiconductor element encapsulation or for optical lenses, obtained using cured silicone resin compositions that contain organopolysiloxane having 2 or more non-covalent double bond groups per molecule, organohydrogenpolysiloxane having 2 or more silicon atom-bonded hydrogen atoms per molecule, and a catalytic amount of platinum catalyst. Patent documents 4 and 5 describe hot-melt silicone resin compositions that are non-fluid at 25° C., have low surface tackiness, and are easily melted by heating.

DOCUMENTS OF THE PRIOR ART

Patent Documents

[Patent document 1] Japanese Unexamined Patent Publication No. 2006-299099

[Patent document 2] Japanese Unexamined Patent Publication No. 2007-246894

[Patent document 3] Japanese Unexamined Patent Publication No. 2006-324596

[Patent document 4] Japanese Unexamined Patent Publication No. 2013-001794

[Patent document 5] International Publication 2015/194158

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

However, when hot-melt film is prepared using a conventional silicone resin composition, the mechanical properties of the resulting film, particularly its strength and extension, are insufficient. Consequently, there are problems in that when used, for example, to form film-shaped or sheet-shaped encapsulant, and film for lamination, in the manufacture of semiconductor packages, the resulting film breaks easily and has insufficient handling workability.

The aim of the present invention is to provide a curable hot-melt silicone composition that can exhibit excellent mechanical properties, particularly strength and extension, even when formed in a film or sheet shape. More specifically, it is to provide a curable hot-melt silicone composition having excellent handling workability, that can form sheet-shaped or film-shaped encapsulant and film for lamination and allows efficient manufacture of semiconductor packages.

Means of Solving the Problem

As a result of their diligent investigation into solving the problem described above, the present inventors arrived at the present invention upon discovering that said problem can be solved by a solvent-free curable hot-melt silicone composition that contains (A) organopolysiloxane having at least 2 alkenyl groups per molecule, (B) resinous organohydrogenpolysiloxane having at least 2 silicon-bonded hydrogen atoms per molecule, at 0.1 to 5% by mass relative to the total mass of the composition, (C) additive represented by average unit formula (C-1):
(R13SiO1/2)a(R12SiO2/2)b(R1SiO3/2)c
(in the formula, R1is an identical or different alkyl group, aryl group, alkenyl group, aralkyl group, or epoxy group-containing organic group, where at least one R1is an alkenyl group, and at least one R1is an epoxy group-containing organic group; and a, b, and c are numbers that satisfy 0≤a≤1.0, 0≤b≤1.0, 0≤c<0.9, respectively, and a+b+c=1), (D) hydrosilylation catalyst, and (E) silica.

In one embodiment of the present invention, component (A) contains resinous organopolysiloxane containing at least one (Ar2SiO2/2) unit.

In one embodiment of the present invention, component (B) is represented by average unit formula (B-1):
(R33SiO1/2)a(R32SiO2/2)b(R3SiO3/2)c(SiO4/2)d(XO1/2)e
(in the formula, R3is an identical or different halogen-substituted or unsubstituted monovalent hydrocarbon group, where at least two R3are hydrogen atoms; X is a hydrogen atom or alkyl group; and a, b, c, d, and e are numbers that satisfy 0≤a≤1.0, 0≤b≤1.0, 0≤c<0.9, 0≤d<0.5, 0≤e<0.4, a+b+c+d=1.0, and c+d>0).

In said average unit formula (B-1), a can be in the range 0.1≤a≤0.9, b can be in the range 0≤b≤0.8, c can be in the range 0.1≤c≤0.9, d can be in the range 0≤d≤0.4, and e can be in the range 0≤e≤0.3.

In said average unit formula (C-1), a can be in the range 0≤a≤0.9, b can be in the range 0.1≤b≤0.9, and c can be in the range 0.01≤c≤0.8.

The alkenyl group content in component (C) can be ≥5 mol % of the total amount of R1.

The epoxy group-containing organic group content in component (C) can be ≥5 mol % of the total amount of R1.

In one embodiment of the present invention, component (A) contains linear, branched, and cyclic organopolysiloxane.

The present invention also relates to a film obtained by solidifying the inventive curable hot-melt silicone composition.

The present invention also relates to an encapsulant comprising the inventive curable hot-melt silicone composition.

The present invention also relates to an optical semiconductor element containing the inventive encapsulant.

The inventive semiconductor element is preferably a light-emitting diode.

Advantages of the Invention

The inventive curable hot-melt silicone composition can exhibit excellent mechanical properties, particularly strength and extension, even when formed as a film or sheet. Therefore, the inventive curable hot-melt silicone composition has excellent handling workability and can form sheet-shaped or film-shaped encapsulant and film for lamination, and allows efficient manufacture of semiconductor packages.

The inventive encapsulant is formed from the inventive curable hot-melt silicone composition and therefore can exhibit excellent mechanical properties, particularly strength and extension, and as a result it has excellent handling workability. Consequently, semiconductor packages can be manufactured efficiently.

