BGA package ball field interaction with manufacturing and design

The ball field design in a flip chip (FC) ball grid array (BGA) often becomes the determining factor for the package body size. This paper describes the physical definition of ball fields for different integrated circuit (IC) product types, and the implications of the same on the package reliability. The printed circuit board (PCB) technology in terms of the manufacturing processes, design rules, and cost is a major factor in the determination of the BGA ball field design. It is the PCB level routing impact that can ultimately dictate the pitches and distribution to be used for the FCBGA ball fields and hence the array size. Optimization of package size and board routing can be achieved using different techniques, and these are discussed in detail. Lastly, in choosing the package size and ball field, the BGA coplanarity concerns, induced by the dynamic package warpage, causing solder joint failures during board assembly, and stress, as well as some manufacturing and test driven ball pattern design rules, impacting solder joint reliability (SJR), are discussed.