This FR4 Double Sided Power Bank Circuit Pcb has undergone a rigorous PCB board test procedure before shipment. It has undergone vision inspection, flying probe, impedance control, solderability testing, digital metallographic microscope and AOI (automatic optical inspection) to ensure its excellent performance. Its number of layers is two layers and the substrate is FR4 (CTI > 240). FR4 Double Sided Power Bank Circuit Pcb uses surface mount technology, through-hole assembly technology, hybrid assembly technology, and traditional lead technology. In addition, it has a conformal coating. Its surface treatment is OSP, ENIG , HASL, lead-free HASL, immersion tin, immersion Sin. FR4 Double Sided Power Bank Circuit Pcb's circuit layer is bonded together by the thickness of an insulating material called a prepreg and a core.