Issue link: https://iconnect007.uberflip.com/i/1379105
42 SMT007 MAGAZINE I JUNE 2021 Analysis of contaminated plating results Contamination from Cl (chlorine) was observed on the PCB pad surface which showed dewetting (Figure 12) compared with a PCB pad surface showing good wetting (Fig- ure 13). e board surface treatment was OSP (organic solderability preservative) on the copper PCB pad substrate. Since the contami- nants inhibit solder wetting, the contaminated pad shows solder de-wetting. A microscope and X-ray image of the solder joint on the con- taminated pad is shown in Figure 14. Assessment of the cause of the contaminated plating defect Based on company experience and knowl- edge with soldering defects, soldering mate- rials and background/ experience with failure analysis work, the cause of the defect in terms of Cl contamination may be derived from the etching agent residue used during PCB pro- duction/fabrication. An insufficient cleaning process was suspected. De-wetting due to contaminated plating can happen on both the PCB as well as the com- ponents. Insufficient cleaning of the plating solution, improper storage conditions aer the plating process, or improper handling by the operator may result in contamination. Since most of the contaminants repel the solder, the contaminated pad shows solder de-wetting. Figure 9: An additional example of the dewetting issue on the pad substrate. Figure 10: Dewetting issue at the component. Figure 11: X-ray pictures of the dewetting issue at the pad substrates. Figure 12: SEM image and EDX analysis on PCB pad surface showing de-wetting.