In some embodiments, the thermal conductivity layer 140 includes a thermal grease, a heat patch, or heat-dissipation double-sided tape. Therefore, when the thermal conductivity layer 140 is disposed between the heat pipe 130 and the speaker module 120, the thermal conductivity layer 140 serves as an adhesive between the heat pipe 130 and the speaker module 120, facilitates the heat transfer between the heat pipe 130 and the speaker module 120, and increases the actual contact area between the heat pipe 130 and the speaker module 120, thereby improving the heat dissipation efficiency of the speaker module 120.

In some embodiments, the thermal conductivity layer 140 is disposed between the heat pipe 130 shown in FIG. 7A and the bottom surface 120a of the speaker module 120. In this embodiment, the thermal conductivity layer 140 is quite thin. Therefore, compared with the heat transfer between the heat pipe 130 and the bottom surface 120a of the speaker module 120 that are in direct contact with each other, the thermal conductivity layer 140 has little great influence on the heat transfer between the heat pipe 130 and the speaker module 120. Further, the thermal conductivity layer 140 serves as an adhesive between the heat pipe 130 and the speaker module 120 to prevent the heat pipe 130 from falling off from the speaker module 120 during vibration of the speaker module 120.