How to Successfully Design a BGA

October 26, 2016 Charley Yap

bga pcb design rules example

Finding exit routes in a BGA

BGA PCB Design Rules

Currently, the standard for housing a variety of advanced and multifaceted semiconductor devices like FPGAs and microprocessors is done through Ball Grid Array (BGA) device packaging. BGA packages for embedded design has evolved significantly over the years, to keep up with the technological progression of chip manufacturers.  This particular type of packaging can be broken down into standard BGAs and micro BGAs. With today’s electronics technology, the demand for I/O availability poses a number of challenges, even for experienced PCB designers, due to multiple exit routes. What are some strategies we can use to successfully overcome these BGA PCB design challenges?

BGA Strategy 1: Defining Suitable Exit Routes

The primary challenge to PCB designers is developing suitable exit routes that won’t cause PCB fabrication failures or other issues. There are several Printed Boards specifics that you need to ensure proper fan-out routing strategy, including pad and via size, number of I/O pins, number of layers required to fan out the BGA, and trace width spacing.

BGA Strategy 2: Determining Required Layers

There’s also the question of how many layers a PCB Layout should have, which is never an easy decision for a . More layers mean higher the overall cost of the product. On the other hand, sometimes you need more layers to suppress the amount of noise that the Printed Circuit Board could encounter.

Once a has determined the trace and space width of the PCB design, the size of the via, and the amount of traces in a single channel, they can then ascertain the number of layers that they need. The best practice is to minimize the usage of I/O pins, to have fewer layers. Commonly, the first two outer sides of the device do not require vias, while the inner section requires vias to be routed underneath it.

Many designers call this the dog-bone. It is a short trace from the pad of the BGA devices, with a via at the other end. The dog-bone fans out, partitioning the device into four sections. This allows the remaining inner pads to be accessed by another layer and provides an escape route out just beyond the edge of the device. The process will continue until all pads completely fanned out.

partitioning bga into four sections
Partitioning a BGA into Four Sections for Easier Pad Access

Learn More BGA Design Strategies

Designing a BGA is no easy task. It requires a number of design rule checks (DRC), to ensure proper width spacing for all traces, as well as careful study, to determine how many layers are needed, in order for the design to be successful. As technology continues to grow at a rapid rate, so does the challenge each designer faces, to route their design into very tight spaces.

BGA PCB Design rules are important, learn more about how to successfully design a BGA in your PCB design software by downloading a free white paper.

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About the Author

Charley Yap

Charley currently serves as a Field Application Engineer at Altium and is responsible for providing technical assistance to Corporate Strategic Account Managers, Sales Managers, Resellers, and Application Engineers. He is also in charge on establishing and managing technical relationships with clients, partners and industry leader. Charley graduated from University of California San Diego majoring in Electrical Engineering, specializing in Power Engineering. However, he's been focusing in the EDA industry for 7 years.

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