We’ve all heard that those who forget history are doomed to repeat it, and our school systems work hard to teach students how to avoid those painful, misery inducing historical mistakes. Similarly, if designers don’t learn from past mistakes, those errors can return to haunt new products, resulting in degraded lifetimes, improper operation, and outright failures. Design engineers must know as much as possible about such failure mechanisms and ways to avoid them. A few painful history lessons and horror stories are recounted below, along with the escape routes and tricks to avoid these deadly design snares.
Flip-Chip BGA Failure Mechanisms
Flip-chip ball-grid array (FC-BGA) packages are very popular for high-performance ICs(Fig. 1).
They can provide great thermal dissipation through metal lids that conduct and spread heat into heatsinks attached to the package surface. They also can provide clean power and ground distribution and excellent signal propagation through appropriately applied power and ground planes and signal layers in the design. However, this package structure is prone to certain failure mechanisms if care is not taken(Fig. 2).