An electronic assembly includes a PCB (20), a socket (22) mounted on the PCB, a CPU (24) connected with the socket, a heat sink (10) in thermal contact with the CPU, a foldable back plate (30) attached to an underside of the PCB and a base plane (40) forming four bridges (42). The back plate includes a first piece section (32) and a second piece section (34) pivotally joined together by a pivot (36). The first and the second piece sections each comprise two legs inserted into two corresponding bridges. Screws are used to extend through the heat sink, the PCB, the bridges to threadedly engage with the legs of the back plate, respectively. The pivot is located under a part of the PCB at which the CPU is mounted.