A tray assembly includes a base tray, and an anti-slip pad disposed on the base tray, wherein the anti-slip pad has a friction coefficient in a range of about 0.5 to about 20 based on ASTM D1894, and a surface resistance in a range of about 10{circumflex over ( )}6 Ω/cm2 to about 10{circumflex over ( )}9 Ω/cm2 based on ASTM D257, and the anti-slip pad includes at least one of a thermoplastic olefinic elastomer (TPO), natural rubber, styrene-butadiene rubber (SBR), and polypropylene (PP).