A handoff system and method using an MPTY service in a mobile communication system. Therefore, it can prevent the optical modules from being damaged by the system power when the optical communication boards are mounted on the optical communication system. a BGA structure, in which the output end of a built-in switch circuit is connected to multiple terminals of the grid array structure, thereby reducing the current that flows through each of the multiple terminals below a permissible level and minimizing the heat due to contact resistances of the multiple terminals in contact with the IC socket of the semiconductor device.