LED and an organic EL device consume less electricity, and recently attract the attention as a new lighting device. In a device for lighting, a substrate and a package material, having high optical reflectance are required in order to effectively utilize light emitted from a luminous body. For example, alumina ceramic having relatively high optical reflectance, or a substrate having provided on the alumina ceramic an light reflective film comprising a metal has been used as the conventional package material of LED element. However, optical reflectance of a substrate and a package material is required to be further improved in order to obtain sufficient quantity of light as automotive lighting, display lighting and general lighting.
To achieve the above object, Patent Document 1 describes a light reflective substrate obtained by sintering a mixture of a glass powder and a ceramic powder, as a substrate having relatively high optical reflectivity. Specifically, the light reflective substrate described in Patent Document 1 comprises glass-ceramic containing a glass powder and a ceramic powder, wherein in a cross-section of the glass-ceramic, an area occupied by particles having a particle diameter of from 0.3 to 1 μm of the ceramic particles is from 10 to 70%. Thus, in Patent Document 1, high optical reflectivity is achieved by containing a large amount of ceramic particles having very fine particle size in the substrate.
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