CURABLE WHITE SILICONE FORMULATION, A REFLECTIVE MATERIAL FOR OPTICAL SEMICONDUCTOR MODULE, AND OPTICAL SEMICONDUCTOR DEVICE

[Objective] To provide a white curable silicone composition that provides excellent elongation characteristics while providing sufficiently great hardness, which as a result can provide a cured product having excellent toughness.[Solving Means] The abovementioned objective can be achieved by a white curable silicone composition comprising: (A) alkenyl group-containing resinous organopolysiloxane which is represented by an average composition formula: (R13 SiO1/2)a(R12SiO2/2)b(R1SiO3/2)c(SiO4/2)d(X O1/2)e, where, in the formula, R1 are each independently a monovalent hydrocarbon group, while at least two R1 are alkenyl groups, X is a hydrogen atom or an alkyl group, 0 ≦ a≦ 0.7, 0 ≦ b ≦ 0.2, 0 ≦ c ≦ 0.3, 0 ≦ d ≦ 0.8 , and 0 ≦ e ≦ 0.2, a + b + c + d = 1.0, and c + d > 0 are satisfied; (B) linear alkenyl group-containing organopolysiloxane which is represented by R2R32 SiO(R32SiO)nSiOR2R32, where, in the formula, R2 is an alkenyl group, R3 are each independently a monovalent hydrocarbon group other than an alkenyl group, and n is an integer of 50 or greater; (C) organohydrogenpolysiloxane having at least two hydrogen atom-bonded silicon atoms in one molecule; (D) a catalyst for curing reaction; and (E) a white pigment, wherein the component (A) is included in an amount of 20 mass% or more based on the total mass of the organopolysiloxane components, and the alkenyl group content in the components (A) to (C) is 1.7 mass% or less.