| How do I mechanically/visually inspect BGA devices when they are soldered to a PCB for possible solder, or other, defects as a first step before part removal and further analysis? I have had board failures due to poor soldering--I think? I can press on the BGA device and the system passes, let go and it fails. | I am interested in your thoughts regarding CSAM, Xray, or other, means of | inspection. Any recommendations on equipment or methods? One way is to perform X-Ray first using whatever available to provide clear image. If you don't have hi-res grey scale, use outside NDT lab to have hi-res black and white done. This provides an excellent image (often better than grey scale types) of the entire array and connections. You will see white areas where voids or cracks reside. If you clearly identify them, the next step would be to X-Section likely failures and determine what resides within the cracks or voids. This may be done if you suspect contamination as flux residue remaining to fight oxidation, as an example. SEM/EDX analysis is useful to determine contamination present - as a possible failure mechanism (others may include thermal or mechanical stress/shock) - then you may prevent its recurrance. Earl Moon
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