When potential process defects begin showing up underneath BGAs in 
electronic assemblies, there are numerous failure analysis tests that 
can be used to troubleshoot process problems.
In determining potential assembly defects at BGA locations.  The first 
level of BGA failure analysis is visual inspection with the aid of a 
microscope or borescope.  The next level of visual inspection, which 
may, in some cases, allow for inspection into the third row of the area 
array device, will be via a borescope. This visual inspection tool is 
especially useful when neighboring components are only a few millimetres 
from the perimeter of the BGA.

In addition to these visual techniques, X-ray imaging will also help to 
diagnose and troubleshoot the process being investigated.  There are 
numerous anomalies and defects that can be seen through the use of X-ray 
inspection. This is followed by closer, higher magnification inspection 
of “areas of interest.”  Shorts and violations of minimum electrical 
clearance are common problems which can be measured and found using 
X-ray inspection. Besides, Dye and pry testing is a relatively simple, 
cost-effective destructive method for testing the integrity of the 
solder joint on a BGA package. The method does not require any high-end 
capital equipment instead of relying on generally available 
investigative or production tools. Testing of this type can be 
outsourced to failure analysis test labs or be done by the user.

If no failures are indicated by the dye, then other test methods such as 
cross-sectioning, acoustic microscopy, and EDX or SEM analysis may be 
the next steps in finding a root cause in the BGA solder joint failure 
analysis.

source smartronics