John,

Saw your question about BGA. I'm not sure about your definition of "balls." Do you mean
eutectic solder balls?

When it comes to placement, most folks always use solder paste no matter if the balls are
eutectic or high temperature types. Is this where you are going? Just need clarification.

As for thermocouples, I use a test board to set profiles for first time BGA's as I'm sure you
do. For optimum placement for the most revealing and accurate readings, drill a hole in one
or several BGA holes and insert the couples in them and measure temps "in the solder joint"
as it is being formed during reflow.

Earl Moon

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