Abstract: A screw installation device is provided, including a base having a tray for carrying a circuit board, a vertical holder vertically disposed on the base, an accommodating unit, an elastic unit, and a double-link horizontal holder having one end connected to the vertical holder and the other end connected to the accommodating unit for accommodating an electric screwdriver. The double-link horizontal holder adjusts the position of the accommodating unit such that the electric screwdriver is movable with respect to the tray in both vertical and horizontal directions. The elastic unit is mounted on the double-link horizontal holder for providing the accommodating unit with an upward elastic force after a downward force is exerted on the electric screwdriver for installing the screw. The present invention eliminates the adverse effects such as reduction in service life and scratching of the product as a result of slippage of the electric screwdriver head.

Abstract: A back case for use with a portable electronic device has a connection element for electrical connection with the portable electronic device. The back case is characterized in that the back case has a back cover and a sidewall; the back case has a receiving space; the back cover has a plurality of holes; the holes are positioned proximate to an end side of the back cover; the portable electronic device is received in the receiving space provided by the back case; the holes provides a resilient deformation force for the back case, so as for the portable electronic device to be fixed in place by the sidewall. Due to the holes of the back case, the back case can be mounted on or dismounted from the portable electronic device easily.