Mitigating Supply Chain Obsolescence: Ball Grid Array Packaging for High Pin Count Products

Ensuring long-term component support with onshore BGA assembly

In part one of our exploration of the manufacturing puzzle, we reviewed the history of semiconductor assemblies moving away from classic lead frame assembly. In summary, the significant tooling investment for lead frame packages, such as PDIP, PLCC, PQUAD, or PGA, drives higher costs and is leading the market to move toward substrate Ball Grid Array (BGA), Quad Flat No-lead Package (QFN), and Dual Flat No-lead Package (DFN) type assemblies.

In part two, we delved into the move toward QFN and DFN technologies and the benefits these provide for lower pin count products. The industry driver of cost investment for lead frame packages and processing complexity are major factors driving the industry to the QFN and DFN technologies.

In part three of the series, we covered silicon, fabrication processes, and wafer storage, and how they play into the manufacturing puzzle for mitigating obsolescence.

Here in part 4, we will conclude our series with a discussion of the migration to substrate BGA packages for high-pin count products.

Why Substrate BGA packages?

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.

Rochester Electronics - Ball Grid Array Packaging for High Pin Count Products

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.

Rochester has invested in BGA assembly capabilities in our Newburyport, Massachusetts, manufacturing facility to address this industry need. We are positioned to support a wide range of package sizes and ball count BGA packages. We can assist customers wishing to migrate their product from one of the older PGA or QFP package formats to the BGA. This is accomplished through assembly of the customer die in a BGA package and testing of those components. This migration from PGA or QFP can be done in a custom BGA at Rochester, allowing the customer to preserve more board-level signal integrity analysis by keeping signal routes the same. This is another piece of keeping our customers’ systems shipping with minimal or no change to the hardware and no changes to their software.

Package, Substrate, and Lead frame Replication

The industry moved away from lead frame assemblies primarily because technology performance demanded zero wire bonds, and the costs to continue lower volume lead frame assemblies were overwhelming.

Rochester Electronics is aware of and anticipated these trends and simultaneously invested in both lead frame assemblies as well as substrate based QFN and BGA assemblies. With billions of die and wafers under storage and most of them requiring lead frame assemblies, it certainly was a logical decision to do so. Not only is Rochester investing in expensive trim and form options for PLCC packages no longer available from the largest assembly house in the world and is quickly exiting from many others, but we have amassed a long-term US-based assembly factory that can support almost all assembly types in existence.

Rochester’s Package, Substrate, and Leadframe Replication Capabilities include: