Touch panel assembly and portable electronic device

A touch panel assembly includes a touch panel and a flexible circuit board structure. The touch panel includes a sensing array, pads and connecting traces. The sensing array includes sensing units. The pads are disposed on a bonding region of the touch panel. The bonding region is located at a side of the sensing array. The connecting traces are located outside the sensing array and electrically connect the sensing units to the pads to actuate the sensing array. The flexible circuit board structure includes bonding portions and at least one key portion. Each bonding portion is disposed at the bonding region and includes a plurality of terminals electrically connected to the pads. The key portion includes a key circuit. The key portion is disposed between any two adjacent bonding portions. The bonding portions and the key portion are arranged along a direction substantially parallel to the side.