Seektronics

  1. T ransformer drawings, PCB , schematic diagrams of the three transformer fly-by-wire bit number need to be one.   Reason: Safety certification requirements   This is a fault that many engineers will make when applying for safety certification submission.   2. The discharge resistor of X capacitor should be put in two sets.   Reason: UL62368, CCC certification requires to disconnect a group of resistors  and test the residual voltage of X capacitor   Many novices will make a mistake, and the only way to correct it is to change the PCB Layout  again, which will waste our time and the procurement of samples.   3. The PCB  aperture of transformer flyline shall take into account the maximum flyline diameter. If necessary, two groups of large and small PCB holes shall be reserved.   Reason: to avoid assembly  difficulties or furnace empty welding problems   Because safety application certification usually has a series, such as 24W application for a series, which contains 4.2V-36V volt

Polarity components require special attention throughout the PCBA process, as errors in directional components can lead to batch accidents and failure of the entire PCBA board, so it is extremely important that engineering and production staff understand SMT polarity components.   l  Polarity definition   Polarity means that the positive and negative poles or the first pin of the component are in the same direction with the positive and negative poles or the first pin on the PCB(printed circuit board). If the direction of the component does not match with that on the PCB, it is called reverse defect.   l  polarity identification method   1.  Resistor  without polarity 2.  Capacitor 2.1 Ceramic capacitors  without polarity 2.2 Tantalum capacitors  have polarity PCB board and components positive marking: 1) colour band marking; 2) "+" sign marking; 3) angled marking. 2.3 Aluminium electrolytic capacitors  have polarity Part marking: colour band for negative; PCB board marking: