Rick Folea
Ricreations

The good news is BGAs are great for reducing board space, improving electrical characteristics of circuits and dealing with thermal issues. The bad news comes when you get that first prototype board back from the shop, plug it in and nothing happens—and all of the signals needed to debug the problem are under the BGA packages. This paper introduces a new genre of tools that use boundary scan in a new paradigm for quick, easy, and inexpensive access to all of those otherwise unreachable signals.