specs or guidlines for how many times you can rework a bga site

First, this is a very interesting question.

Second, there is no specification.

Third, companies develop guidelines for rework based on their expectations for their product reliability. Things to consider are: * Motorola allows no product shipments with reworked BGA. There may be references to this policy in the fine SMTnet Archives. If you can't find them, we'll try to dig them out. * We allow a total of six thermal cycles on our components. So depending on the process technology, this could be a lot or maybe very few rework cycles. * BGA see an inordinate number of thermal cycles [ie, ball attach, component attach, component removal, site dress, reballing, rework attach, etc], as compared to other components.

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