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Mon, 14 Sep 1998 09:24:32 +0200 |
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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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