BGA LAND PATTERN and ASSEMBLY Issues

摘要

Designers face a number of issues when working with BGAs: pad layout, cost, manufacturability and reliability of the final product. Assemblers may encounter a number of issues too. In addition, even though fine-pitch BGAs are not standard, they have become popular. Herein are the main issues that designers must be aware of when using BGAs, in particular the effect as pitch decreases from 1.27 mm to 0.4 mm. BGAs were introduced as a packaging technology counter to peripheral-leaded surface mount components, in order to address space and functionality demands. Peripheral-leaded components such as quad flatpacks (QFPs) are characterized by leads that extended from the perimeter of the component body. These leads provide the electrical requirements and mechanical joints to the PCB. In BGAs, the interconnect location is below (at the base of) the package, in the form of balls (FIGURE 1). These balls are either eutectic tin-lead solder or high-melt solder consisting of 90% lead.