emission module in practice the above mentioned disclosure may also be applicable to a light emitting element a light emission device or a display device for example the light emission module with the thermal vias 162 may be used to a light emission device such as a lighting tube or a lighting lamp moreover the above mentioned light emission module may be combined with a display pane to form a display device such as a liquid crystal display device lcd or a variable message sign vms in addition the above mentioned substrate body incorporated with the thermal vias may be used in semiconductor and integrated circuits components in order to improve the heat dissipation efficiency referring to fig1 a light emitting device 1000 may comprises an optical sheet 1600 a plurality of light emission modules 1100 and a light guide plate lgp 1400 disposed therebetween each of the light emission modules 1100 may comprise a plurality of led chips and a substrate unit as mention above detailed description thereof omitted the lgp 1400 is adapted to guide light beams provided by the light emission modules 1100 to emit toward the optical sheet 1600 in particular the lgp 1400 may comprise a bottom surface not labeled and a light emitting surface not labeled opposite to the bottom surface the optical sheet 1600 is configured to convert light beams emitting from the lgp 1400 into uniform planar light and thereby ensuring the lighting quality.