Guide on PCB Solder Finish Common Cause of Failure Available for Download

Based on recent surveys, PCB solder finishes are one of the most common cause of soldering defects and rejection of PCBs during assembly. Design and Process Engineers highlighted solder finishes 35 percent, with delamination at 25 percent, third place were cosmetic faults.

Another survey conducted as part of the NPL Defect Database creation showed that currently open joint failure is the most common issue seen by industry. Open joints are the most difficult to detect in manufacture. The root cause of these defects can be a simple process control issue or a more complex technical problem requiring laboratory analysis. PCB solder finish was seen as the second biggest issue and is understandable due to the number of different options and the need to change surface coatings for lead free assembly. Many of the open defects could, however, have their root cause based on the finish.

Bob Willis has put together a poster guide covering different pad finish examples at different magnifications, two solderability testing methods and many of the common process problems associated with PCB surface finishes. The poster guide is provided as a pdf file so engineers can download and print examples for display and reference during training or failure analysis. To download the free charts readers can go to http://www.bobwillisonline.com/posters.

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