Single-layer fanout routing and routability analysis for ball grid arrays

Abstract

Fanout routing for Ball Grid Array (BGA) packages becomes non-trivial when the I/O pin count increases. When the number of I/Os gets larger and larger, the number of I/Os we can put on a package may not be 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 presents an efficient algorithm (EVENFANOUT) which generates the optimal uniform distribution of wires. We have found the three cuts that is decisive on the routability of the package using EVENFANOUT. These decisive cuts form the base for design optimization of the package.