Does the Gold Thickness in ENIG PCBs Affect Component Detachment?
Do you know how the thickness of the gold layer in ENIG surface-finished PCBs impacts soldering quality? What role does the gold layer play in PCBA soldering? How could the detachment of electronic components from a PCB be related to the gold thickness in ENIG? Should the gold layer be as thick as possible?
For a while, the SMT contractor managed by Workingbear got into a dispute with the PCB manufacturer. Both parties were debating the gold thickness specifications for ENIG (Electroless Nickel Immersion Gold) surface-finished PCBs. The issue arose because the EMS (Electronic Manufacturing Services) factory recently used a batch of ENIG PCBs, and during the final assembly after surface mount and board-level testing, components were found detaching from the PCB. Initially, the SMT factory strongly believed that the detachment was caused by the “black pad” issue commonly associated with ENIG. From the appearance, the pads where the components had detached showed the characteristic black pad color. Most of the pads had come off the board entirely, sticking to the component leads. The theory was that the solder fracture might have occurred at the Electroless Nickel (EN) layer or the phosphorus-rich (P-rich) layer.
