The Printed Circuit Designer’s Guide to… Stackups: The Design within the Design

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If you have ever contemplated crosstalk, eye closure, power loss, or a list of other issues defined in this textbook, then you also need to understand what, why, and how stackups can and will impact your circuit’s performance. After all, the stackup is one of the few things that directly touches every single part of your design; therefore, you must set yourself up for the highest probability of success by establishing a strong foundation through a well-designed stackup. 

There are many incredible resources out there for those in the high-speed design industry: Eric Bogatin’s Signal & Power Integrity Simplified, Lee Ritchey’s Right the First Time, and a host of other books and websites. However, there is an apparent void in the realm of stackup design. How has industry gone so long avoiding such an important topic as one that influences everything on the board? The Printed Circuit Designer’s Guide to… Stackups: The Design within the Design begins to fill the industry-wide void in an easy-to-understand overview that helps define the aspects that you as the engineer need to be thinking about when putting together a stackup. 

With 25 years of experience in PCB manufacturing and signal integrity, author Bill Hargin is an expert in the field of stackup design and it shows here. In Chapter 3, Bill shows how your dielectric of choice will directly impact your “eye.” He explains the breakdown of how each variable contributes to the overall loss budget, then defines how he recommends material planning before any routing has begun. This book helps the reader establish the variables of interest and the impact of those variables, and makes a recommendation on what to do about it so you can improve your future designs. 

Boards are getting thinner, power requirements are increasing, and routing densities are becoming finer. You will need to make compromises in your stackup, so understanding that trade space is vital. This book breaks down concepts like board loss, material selection, impedance planning, and more to help you understand how each one of them will influence your design when fabricated. This book will assist you in learning how to make educated compromises earlier in the design cycle. 

If you are a hardware or electrical engineer who is not already deeply invested in stackup design, this book is really for you. It is full of practical information, not bogged down by technical jargon, has easy to understand and useful images, and gets you off to the races quickly. Even the seasoned veteran will find this book a worthy reference for understanding when one needs to know things like the contribution percentage of each variable on impedance. Regardless of where you are in your stackup knowledge, I recommend downloading the book and reading it! It will be well worth your time and may just save you future headaches. 

Skyler Sopp is a signal integrity engineer for Mercury Systems.  

This article originally appeared in the April 2022 issue of Design007 Magazine.


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