As illustrated in Table 1, reflectance of samples No. 3 to 8 was equal to or more than 91.3% and was higher than that of samples No. 1 and 2. From these results, it was found that a circuit board had a high reflectance when its silicone-resin layer contains equal to or more than 45% by mass of the plurality of fillers and the first filler, whose aspect ratio was larger than 5, occupied equal to or more than 5% of 100% of the total number of the fillers.

Among samples No. 3 to 8, reflectance of samples No. 3 to 7 was equal to or more than 92.4%, namely high. From these results, it was found that a circuit board had a higher reflectance when a filler content of its silicone-resin layer was equal to or less than 80% by mass.

Among samples No. 3 to 7, reflectance of samples No. 3 to 6 was equal to or more than 93.0%, namely high. From these results, it was found that a circuit board had a further higher reflectance when the first filler occupied equal to or less than 40% of the number of all of the fillers.

Next, samples were fabricated whose number ratios of the second filler in a silicone-resin layer were different from one another to execute measurement of their reflectance.