Array packages, initially introduced with PGA, and now commonly realized with BGA, are the key enabler to products needing a high number of signals coming in and out of the package. When connecting to the Printed Circuit Board, (PCB), with an array of connections underneath the package body, rather than a row of connections along each side of the package, the package’s area per signal is significantly reduced. Array packages successfully connect hundreds of signals from the IC to the PCB.

Having established the signal density benefit of array packages versus dual in-line (DIP) or quad flatpack (QFP), let’s touch on the migration from PGA to BGA. The core mechanical difference is that the BGA is connected to the PCB with surface mount technology, whereas the PGA is connected to the PCB with through-hole technology. The manufacturing costs, due to automation and complexity, favor surface mount technology. Additionally, the assembly process of the BGA component is simpler, and thus lower cost. The BGA is based on a substrate on which the IC die is mounted, designed to route IC bond pad signals to solder ball connections in the array. The BGA package can accommodate either wirebonded or flip-chip die, as needed for each specific product.

In the case of flip-chip, much of the routing is accomplished on the die with the redistribution layer to the bumps, with minimal routing required within the BGA substrate to reach the package solder balls. This eliminates wirebonds in the package, enabling higher performance. These substrates are manufactured in panel form which comprises a grid of substrates. This allows multiple units to be processed in parallel through assembly operations. When these operations are completed, the panel is sawn into the final components. The bottom of the package is the array of solder balls connecting the IC to the PCB through surface mount technology. These solder balls replace the electrical pins of the PGA.