Why are holes not conductive after SMT Poor Drilling: Dust left in the holes after drilling, especially in those larger than 0.3mm, can prevent copper from being properly plated during the copper plating process, leading to non-conductive vias. Such defects are usually detected during electrical testing and result in the PCB being scrapped. Copper Plating Defects: Insufficient copper plating time can result in thin hole walls that may dissolve during high-temperature reflow soldering, especially in vias smaller than 0.3mm. For PCBs requiring high current, inadequate copper thickness can cause the copper wall to melt, leading to defects. Designers must specify thick copper plating for high-current boards, such as power supply boards. Unqualified SMT Materials or Technique: Issues may arise from using impure tin, poor-quality flux, or improper SMT techniques, leading to poor soldering, non-functional components, and non-conductive vias, especially in plug-in vias.
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