Gideon received several Browning BTC-7-4K-Edge cameras from the field. The cameras were dead on arrival. The objective was to find the cause of failure.
There was no external physical damage to any cameras
The batteries were replaced with new ones. The camera did not turn on; however, when it was disassembled, the full voltage resided at the solder joints of the printed circuit board.
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. These bubbles are unacceptable and this would be a reject. In class 3, (military use, aviation, and critical applications), such defects cannot be allowed under any circumstances. They have been known to drain batteries, cause leakage current in continuous circuits, and cause corrosion which drops out the circuit altogether.
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. This lack of bonding creates a void like space at the interface of the conformal coating and the board surface. This space is where electromigration can occur. This PCB failed many of the IPC-A-610 criteria in addition to many of the test methods used to evaluate ionic contamination.