The present invention relates to a mobile phone including a main printed circuit board. A first connector and a second connector are welded respectively onto a first predetermined location and a second predetermined location of the main printed circuit board, wherein a first power supply and a second power supply are provided respectively by the first connector and the second connector. The main printed circuit board includes a first portion corresponding to a keypad module and a second portion corresponding to an LCM module. The mobile phone also provides a holder, wherein a space is included in the holder to accommodate the LCM module. A slit is formed at a predetermined location of the holder. The mobile phone further includes a secondary printed circuit board carrying a plurality of LEDs to provide a back light source. The secondary printed circuit disposed within the aforementioned slit includes a first contact point and a second contact point. The first contact point contacts correspondingly with the first connector, and the second contact point contacts correspondingly with the second connector.