A circuit board assembly and a backlight module comprising the circuit board assembly are provided. The circuit board assembly has a first surface and a second surface opposite to the first surface, and further comprises at least one laminate, a first conductive wiring structure and a coating. The first conductive wiring structure is formed on the first surface. The coating is formed on the coating area of the second surface, wherein the coating can conduct heat and provide electric insulation. Thus, the circuit board assembly is adapted to outwardly conduct heat from the laminate through the second surface and to promote the heat dissipation efficiency of the circuit board assembly.