Rob: You say, "We usually determine our run process based on the heaviest components, and propensity for falling off during the second reflow process. If there's only the one BGA on that side of the board, we'd tend to run that side first."
We agree with the first part, "We usually determine our run process based on the heaviest components, and propensity for falling off during the second reflow process."
We disagree with the second part, which contradicts the first part, "If there's only the one BGA on that side of the board, we'd tend to run that side first."
We usually determine our run process based on the heaviest components, and propensity for falling off during the second reflow process. Period, end of story.
Our old friend Bob Willis theorized that most BGA and flat packs reflow well on the second side, except for the BIG-Honking ones. The BIG-Honking ones fall, not because of too much weight, but because of their size. The amount of flex in BIG-Honking ones is relatively large [because the part is large] and is in a different sequence during heating cycle than the board. [Out of respect for Bob, "BIG-Honking" is our term, not his.]
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