Hello Technet,

I remember a discussion  a couple of weeks ago about X-ray inspection. It was stated that the nr.1 defect that one wishes to see with a X-ray machine  is open joints, but unluckily this type of defect  can only be seen with the most expensive X-ray machines on the market.
I was thinking : if the BGA (the balls) collapses during soldering and  is soldered perfectly parallel to the board surface, all the balls must have reflowed !  If only one of the balls didn't melt,  the component can not be soldered  parallel to the  board surface ! 
Since the chance that  a collapsed ball  forms a joint with the pad is almost 100 % ,  it can be concluded that X-ray inspection for "opens" does not make much sense.  Just looking at the parallellity should tell you enough !! 

What do you think, is this a reasonable thought or am I overlooking some things ??

Regards,


Daan Terstegge
Signaal Communications
* Unclassified *

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