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

Downloads

Download the latest in PCB design and EDA software

  • PCB DESIGN SOFTWARE
  • Altium Designer

    Complete Environment for Schematic + Layout

  • CircuitStudio

    Entry Level, Professional PCB Design Tool

  • CircuitMaker

    Community Based PCB Design Tool

  • NEXUS

    Agile PCB Design For Teams

  • CLOUD PLATFORM
  • Altium 365

    Connecting PCB Design to the Manufacturing Floor

  • COMPONENT MANAGEMENT
  • Altium Concord Pro

    Complete Solution for Library Management

  • Octopart

    Extensive, Easy-to-Use Component Database

  • PRODUCT EXTENSIONS
  • PDN Analyzer

    Natural and Effortless Power Distribution Network Analysis

  • See All Extensions
  • EMBEDDED
  • TASKING

    World-Renowned Technology for Embedded Systems Development

  • TRAININGS
  • Live Courses

    Learn best practices with instructional training available worldwide

  • On-Demand Courses

    Gain comprehensive knowledge without leaving your home or office

  • ONLINE VIEWER
  • 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

    ALTIUMLIVE

    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

    Downloads

    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

    Standard Board Thickness and Your Layer Stack

    Zachariah Peterson
    |  May 5, 2019

    Tom’s Restaurant from Seinfeld

    I’ll confess that I have a love for 1990’s sitcoms. If Jerry Seinfeld were a PCB designer, he would probably ask “what’s the deal with the 1.57 mm board thickness?” It’s a fair question after all, and it makes you wonder why many standard values (e.g., 50 Ohms impedance on high speed transmission lines) are used in PCB design and other areas of engineering.

    There are good reasons why these standard values have found their place in PCB design, and these values have little to do with industry standards. Regarding board thickness, the reason is largely historical, although most manufacturers have tailored their fabrication capabilities to a variety of other thicknesses.

    Board Thickness: A History Lesson

    Lee Ritchey nicely sums up the history of the apparently standardized 1.57 mm board thickness. Without repeating everything the great Mr. Ritchey says about board thickness, we can briefly summarize the reasons this value became something of a standard within the industry.

    When electronic devices were transitioning to transistors and integrated circuits, boards were built using breadboarding on plywood workbenches, where the top layer of a plywood sheet was replaced with a material called Bakelite. If you are familiar with plywood, then you know that the thickness of a single ply in plywood is 1/16 in., or 1.57 mm.

    This thickness became something of a standard when board-to-board connections became necessary. Early board-to-board connections used rack units with edge connectors, and these edge connectors needed to match this standard thickness. Nowadays, instead of Bakelite, we use materials that allow etching and plating, such as epoxy laminates like FR4.

    If you take a moment to think, you’ll realize there is no reason for this thickness to be preferable over any other thickness other than to accommodate the layer count and copper weight that is used in a particular board. Many manufacturers opt for this board thickness with lower layer counts because that’s the way it’s always been, or in order to accommodate a standardized edge connector. Looking throughout the industry, many routing standards (e.g., PCIe add-in cards) specify this value for board thickness to this day.

    As boards have become more complex, and as copper weight and layer counts have increased for different applications, boards tended to become thicker. Two popular board thicknesses are 2.36 mm and 3.18 mm, which just happen to be 150% and 200% of the 1.57 mm board thickness.

    Automated PCB pick-and-place machine

    DFM and Board Thickness

    If you start looking at manufacturer websites, most manufacturers offer fabrication to a variety of thickness values. Although the 1.57 mm value is something of a required capability for any manufacturer, many manufacturers have adapted their capabilities to fabricate boards with various multiples of this thickness.

    Different manufacturers can fabricate boards with different layer counts and copper weights, and many will offer their set of “standardized” board thicknesses. Manufacturers will also limit the allowable board size to specific values for different stackups. Other manufacturers will simply limit the panel size to specific dimensions. You should always check your manufacturer’s capabilities before designing your layer stack in order to keep costs in check and ensure manufacturability.

    Choosing the right layer thickness, and thus the total board thickness, depends on a number of factors. When working with impedance controlled boards, the thickness needs to be carefully controlled and will depend on the desired trace width. The weight of your board, component compatibility requirements, and required connectors are also significant factors. You’ll need to balance all of these alongside satisfying your manufacturer’s capabilities in order to ensure your board is fully manufacturable.

    A stack of PCBs with standardized board thickness

    Whether you are designing a two-layer board or a complex PCB with over a dozen layers, you need PCB design software that gives you full control over your layer stack. The layer stack manager, material stackup library, and full suite of design features in Altium Designer® allow you to design boards for any application you can dream up. All of these features and many more are built into a unified, rules-driven design platform, setting a new standard in the PCB design industry.

    If you’re interested in learning more about Altium Designer, you can download a free trial and get access to the industry’s best design features. Talk to an Altium expert today to learn more.

    About Author

    About Author

    Zachariah Peterson has an extensive technical background in academia and industry. Prior to working in the PCB industry, he taught at Portland State University. He conducted his Physics M.S. research on chemisorptive gas sensors and his Applied Physics Ph.D. research on random laser theory and stability.His background in scientific research spans topics in nanoparticle lasers, electronic and optoelectronic semiconductor devices, environmental systems, and financial analytics. His work has been published in several peer-reviewed journals and conference proceedings, and he has written hundreds of technical blogs on PCB design for a number of companies. Zachariah works with other companies in the PCB industry providing design and research services. He is a member of IEEE Photonics Society and the American Physical Society.

    most recent articles

    Back to Home