04/01/1995 09:00 AM
Computer Engineering
Fanout routing for Ball Grid Array(BGA) packages becomes non-trivial when the I/O pin count increases. With large number of I/Os, the number of I/Os we can put on a package is not always limited by the available area but sometimes by the ability to fan them out on the next level of interconnect---the PCB or MCM substrate. This paper is the first to consider this problem and offers an efficient algorithm (EVENFANOUT) to solve it. EVENFANOUT generates the optimal uniform distribution of wires. Another important contribution is that we analyzed the relationship between pin pitch and the routability of fanout so that the package designer can choose an optimal pitch for maximum routability. Knowing this relationship, we know whether a fanout routing is routable or not before it is routed. This is implemented in the Package Early Analysis and Routing Tool (PEART) for rapid development of Ball Grid Array Packages.
