X-Ray Radiography Inspection This report contains images taken of the BGAs on the two boards provided. There are no significant defects present, however, significant voiding is present throughout the two parts. The last image shows a BGA analysis performed on one of the worst areas of voiding. The analysis shows voiding greater than 15%, but less than 20%.
When run, this feature shows voiding in the solder joints as well as background features such as traces and vias, all within the same image.
This is a class 2 inspection of a printed circuit board (PCB) using the IPC-A-610 Rev E. There is a bubble between the two solder joints of the opposite polarity battery terminals.
These enclosed mini-environments are known repositories for ions which will conduct when a voltage is applied. The leakage current drain is often dependent on the amount of moisture present in the atmosphere since the inside bubble environment will equilibrate with the surrounding atmosphere.
This vendor from China was in the process of qualification. There are solder dross and conductive flux underneath the conformal coating. Solder dross is highly conductive and flux will activate as an ionic conductor across leads, pads, terminals, etc.
Conformal coatings inhibit the crosstalk and ionic migration across the PCB surface. If, however, these contaminants reside on the board surface, the conformal coating cannot make contact with the solder mask and does not bond properly.