Free Trials

Download a free trial to find out which Altium software best suits your needs

How to Buy

Contact your local sales office to get started on improving your design environment


Download the latest in PCB design and EDA software

  • Altium Designer

    Complete Environment for Schematic + Layout

  • CircuitStudio

    Entry Level, Professional PCB Design Tool

  • CircuitMaker

    Community Based PCB Design Tool


    Agile PCB Design For Teams

  • Altium 365

    Connecting PCB Design to the Manufacturing Floor

  • Altium Concord Pro

    Complete Solution for Library Management

  • Octopart

    Extensive, Easy-to-Use Component Database

  • PDN Analyzer

    Natural and Effortless Power Distribution Network Analysis

  • See All Extensions

    World-Renowned Technology for Embedded Systems Development

  • Live Courses

    Learn best practices with instructional training available worldwide

  • On-Demand Courses

    Gain comprehensive knowledge without leaving your home or office

  • Altium 365 Viewer

    View & Share electronic designs in your browser

  • Altium Designer 20

    The most powerful, modern and easy-to-use PCB design tool for professional use


    Annual PCB Design Summit

    • Forum

      Where Altium users and enthusiasts can interact with each other

    • Blog

      Our blog about things that interest us and hopefully you too

    • Ideas

      Submit ideas and vote for new features you want in Altium tools

    • Bug Crunch

      Help make the software better by submitting bugs and voting on what's important

    • Wall

      A stream of events on AltiumLive you follow by participating in or subscribing to

    • Beta Program

      Information about participating in our Beta program and getting early access to Altium tools

    All Resources

    Explore the latest content from blog posts to social media and technical white papers gathered together for your convenience


    Take a look at what download options are available to best suit your needs

    How to Buy

    Contact your local sales office to get started improving your design environment

    • Documentation

      The documentation area is where you can find extensive, versioned information about our software online, for free.

    • Training & Events

      View the schedule and register for training events all around the world and online

    • Design Content

      Browse our vast library of free design content including components, templates and reference designs

    • Webinars

      Attend a live webinar online or get instant access to our on demand series of webinars

    • Support

      Get your questions answered with our variety of direct support and self-service options

    • Technical Papers

      Stay up to date with the latest technology and industry trends with our complete collection of technical white papers.

    • Video Library

      Quick and to-the-point video tutorials to get you started with Altium Designer

    Stacking The Odds In Your Favor: Mastering The Art of Stackup Design

    Kella Knack
    |  July 23, 2019

    As everyone knows, the PCB stackup is the substrate upon which all design elements are assembled. And, it is incumbent upon the product development engineer to own the PCB stackup process which includes calling out the exact type of laminate, prepreg and copper needed in every layer of the stackup as well as taking into account all of the electrical characteristics of the PCB to ensure a design that is fully functional from both a mechanical and electrical standpoint. In the final analysis, a poorly designed stackup using inappropriate materials can degrade the electrical performance, the power delivery, the manufacturability and the overall reliability of the finished product.

    This blog will address the history of the PCB stackup process, the challenges associated with a poorly executed stackup, and the ways to ensure that your stackup is optimized for all product development operations.

    When Stackups Became a Concern

    In the early days of PCB design, all that mattered was that the final manufactured board be of the right thickness at the lowest possible cost. Within these loosely-structured parameters, material selection was left up to the fabricator. There were two materials of choice: FR-4 and polyimide. Since the specification of these materials was so unstructured, it was possible to get a different board from every fabricator primarily because the PCB was built from whatever material the fabricator had in the Storeroom.

    An interesting aside about polyimide: Everyone has always assumed that polyimide was the laminate of choice for aerospace applications because it withstands heat better than other materials. In truth, the limitation of the heat is based upon what the components can tolerate. Any of the materials that are designated as “not polyimide” are more than good enough for almost all components. The real reason for polyimide as a laminate was that the boards made from it were most often repaired in the field and field technicians weren’t expert at soldering. If a board wasn’t polyimide, when parts were replaced, the pads would come off the board. Thus, selecting polyimide was based on its tolerance for rework not because it could withstand high temperatures. 

    The foregoing initial practice of material selection worked fine as long as we didn’t care about any electrical aspects of the PCB such as impedance, crosstalk, loss and power delivery. Once these factors came into play, it became a whole different ballgame that required a whole new level of skill sets.

    The first issue of concern was the resistance to the flow of the electromagnetic energy along a transmission line or through a component, aka impedance. And, the burden was placed on the board fabricator to get the impedance correct. As this was not within the skill sets of board fabricators (nor should it ever have been expected in the first place) the process of getting the impedance right was hit and miss. Even today, if the impedance compliance onus is placed on the fabricator, it’s still a catch-as-catch-can proposition.

    As we started to go up the PCB speed curve, the next area that needed addressing was the unwanted interaction between signal wires or traces traveling in parallel—aka crosstalk or coupling. There never was a point in time during which the fabricator could successfully deal with this design consideration. Thus, this particular design aspect was the first that required engineering teams to factor stackups into their overall product development efforts.

    Following impedance and crosstalk, power delivery and plane capacitance had to be accommodated as PCBs became increasingly fast and more complex. Today, we are concerned with loss in the channels and skew, and how they impact stackup operations. What all of the foregoing says is that the product development engineer has to be the master of all of these design aspects. Somewhat surprisingly, there are still some engineers who pretend that they don’t have to address these factors. Not surprisingly, those who don’t are often met with failed products.

    So, all of the electrical considerations have to be engineered and they include:

    • Impedance
    • Crosstalk
    • Power delivery
    • Skew
    • Differential pairs
    • Loss in high-speed channels

    The key thing to remember is that engineering rules-of-thumb will never satisfy the foregoing.

    But, it’s a fair question to ask where new engineers can gain these skill sets as they will definitely need them. The references listed at the end of this article are the best resources available. While there are a lot of other books in print they are often full of errors and bad advice. If they are not listed in this article’s references, it’s safe to assume that they fall into the “don’t use” category. And, it goes without saying, the average component applications notes are not good sources of information as they are commonly based on rules-of-thumb.

    Once all of the above electrical considerations have been met, the following can then be determined:

    • The number of signal layers needed.
    • The number of power and ground layers needed.
    • The thickness of copper needed on each layer.
    • The type of laminate that will satisfy all of the mechanical and electrical requirements.

    It might seem, based on what we’ve discussed, that the stackups for complex, multilayer boards would be the most difficult to determine and fabricate. In actuality, the hardest stackups to do are those used for 4-layer game boards. In these configurations, there is no plane capacitor (there can’t be one); there are no other layers than the surface layers that can be used for traces and very complex parts have to be hooked up together without the freedom of changing signal layers. In this scenario, there has to be the utmost cooperation between the person doing the PCB layout and the person selecting the pinout of the ICs. Without this, unscrambling a bus will require multiple signal layers.


    The PCB stackup process is multifaceted and, for today’s high-speed, complex boards, is an integral part of the overall product engineering discipline. Taking all of the electrical engineering requirements into account early-on in the design cycle will guarantee a product that works right the first time while meeting all the mechanical and electrical performance criteria.


    more questions? Call an expert at Altium or read what Altium Designer® can do for your in the process of designing PCB stackups.

    1. Smith, Larry D. and Bogatin, Eric, “Principles of Power for PDN Design-Simplified: Robust and Cost Effective Design for High Speed Digital Products.”

    2. Bogatin, Eric, “Signal and Power Integrity Simplified, (2nd Edition).”

    3. Ritchey, Lee W. and Zasio, John J., “Right The First Time, A Practical Handbook on High-Speed PCB and System Design, Volumes 1 and 2.”

    About Author

    About Author

    Kella Knack is Vice President of Marketing for Speeding Edge, a company engaged in training, consulting and publishing on high speed design topics such as signal integrity analysis, PCB Design ad EMI control. Previously, she served as a marketing consultant for a broad spectrum of high-tech companies ranging from start-ups to multibillion dollar corporations. She also served as editor for various electronic trade publications covering the PCB, networking and EDA market sectors.

    most recent articles

    Back to Home