Chengdu Senlu Electric Co.,Ltd
Difference between COB street light & SMD street light
1, 1).SMD needs to be attached in a bracket, this will lead thermal resistance; then the bracket will be welded in the PCB board, the bracket between PCB board will lead thermal resistance too; furthermore, the PCB board has 3 layers, in the middle of the 3 layers of PCB board, it will also lead to thermal resistance; then the PCB board just attached in the heatsink, they have to use adhesive to attach it, but since the PCB board is very big, in order to reduce cost, they have to use the lower adhesive for not more than 0.3USD/G,the conductivity coefficient of the adhesive could be 2w/m.k,and the thermal resistance will be led more. Therefore, the heat dissipation will not be good since there are many thermal resistance led. There are many small chips, as time went by ,if one of the chip is broken, the whole current of the other chips will be increased, then the chips will be broken one by one.
2),COB no other obstruct, it directly attached in the heatsink, and this could ensure the good heat dissipation. We use the adhesive for 2USD/G,and the conductivity coefficient of this adhesive could be 20w/m.k.And one driver control one cob, so the cobs won’t affect each other.
2,Most conditions, most SMD street light adopt die cast aluminum(ADC12), and the heat conductivity coefficient could be only 96w/m.K;while our COB street light use extrusion aluminum(AL6063), the coefficient could be 201W/m.K.
3,The SMD has a pc cover in around the chips, as time went by, it will turn yellow, this will lead to luminous depreciation, and also they will use tempered glass to cover outside the lamp.While the COB don’t have this kind of pc cover, even we will use a optical glass covers the cob, but the glass won’t form lumens depreciation.
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