4. Circuit design and welding technology of power-supply productsThe judging of LED Lights circuit design can simple done in direct ways. For example, the components shall be in good order with clean and neat welding points. As we all know, mechanical welding is certainly better than manual welding. The difference of these welding methods is the red gum in the back. The flashing lights are basically due to power source failure or lacking of sufficient welding. And the problem of lack welding cannot be detected by aging test. Therefore, we need AOI to test the SMT quality of power source.