Multimetal DTAB packages for a 125-MHz computer

The authors discuss the challenges in packaging a 430-pin IC chip that operates at 2 V and draws 15 A, with risetimes of about 200 ps. A 407-pin multilayer ceramic package (pin grid array) was first evaluated for this application and failed most of the noise specifications. An analysis of the failure mechanisms led to the design of a two-metal 432-pin TAB (tape automated bonding) package. Performance capabilities and limitations of these two packages are compared through detailed simulations and actual measurements. It is concluded that TAB packages meet or exceed the performance goals for low transition times and/or large operating currents. The initial design was modified with the addition of a third metal layer. Performance results on this three-metal TAB are also included