TABLE OF CONTENTS As the technology advances in IC density, speed, and function, so does the need for improved packaging performance. The trend toward higher device frequencies and higher I/Os on chips increases the need for an optimized next level of packaging hierarchy or interconnect. The focus is on improving both the electrical and thermal performances of the package (or substrate) and its density for enhancing the functionality of the finished device. A high-density substrate (or interconnect) should have the following characteristics:1 7
Enhanced mechanical, electrical, thermal, physical, and chemical properties, such as low relative dielectric constant, low moisture absorption, low dissipation factor, low thermal coefficient of expansion, high glass transition temperature T g , high thermal conductivity, high copper ductility, high copper peel strength, high dimensional stability, good solvent resistance, good chemical resistance, and high reliability
Microvias
High-density and fine-line circuitry while ensuring signal integrity
Enhanced adhesion of thin metal films to the dielectric and base substrate
The substrate (or interposer) of a solder-bumped flip chip (FC) constitutes a very critical element in a PBGA package. Important functions of the FC-PBGA interposer are shown in the following list:
To provide a path for the electrical current that powers the circuits on the chip
To enhance device performance beyond interconnection wiring
To route signals
To reconnect data from one sector of the chip to another
To increase density and switching speeds
To improve bandwidths and control impedance
To utilize integral inductive/resistive/capacitive layers
To help to remove the heat from...
