A flash memory device includes a Chip-On-Board (COB) type circuit board and a number of first and second contacts electrically connected to the circuit board. Each first contact includes a stiff first contact portion formed on an upper surface of the circuit board. Each second contact includes a cantilevered planar second contact portion extending along the front-to-rear direction. When the flash memory device is inserted into a USB 3.0 receptacle connector, the first and the second contact portions jointly electrically connect with the USB 3.0 receptacle connector. The planar second contact portions provide larger contacting area for mating with the corresponding contacts of the USB 3.0 receptacle connector.