Features

Analytical formulas, plus Microsoft Excel, are all you need.

Look at just about any expert-level signal integrity guide and you will (or rather, should) see a lot of simulation data. Most often, these results are generated with 3-D electromagnetic field solvers, even if the author is not performing simulations directly from a finished PCB layout. 3-D field solvers and 2-D field solvers are also used on the front-end to design and engineer an interconnect for a specific interface.

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Even after a long growth streak, observers still think the industry has life ahead.

The Electronic Systems Design Alliance in October reported yet another staggering quarter for printed circuit board design software sales. Revenues were not only up big year-over-year, but a look at the longer-term historical trends shows just how far the sector has come even in the past few years.

Indeed, over the past seven-plus years, this supposedly mature market has experienced a year-over-year quarterly drop only thrice – in the periods ended September 2016, June 2019 and December 2020 – two of which came during the Covid pandemic. Year to date, revenues are up almost 12%. The June 2023 period, the most recent quarter for which data are available, marked the second-highest quarterly figure, behind the March 2023 period (Figure 1). (The September quarter data are due to be released this month.)

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Analysis and summary of the most fundamental design guidelines.

Technological advantages associated with the use of laser systems include flexibility, material efficiency and performance. To exploit the potential of filigree laser tools it is necessary to know and understand the physical and technological possibilities and limitations. This article focuses on material efficiency and design rules. Various factors are decisive for the design of PCBs, such as components and their heights, and potential mechanical or thermal stress.

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The industry standard formula could triple the number actually required.

If a high-current trace on a board has a via going to another trace segment, the question of via size comes up. Conventional wisdom has always been that the conducting cross-sectional area of the via (or the sum of the vias) should equal or exceed the conducting cross-sectional area of the trace. The IPC standard, IPC-21521, formalizes it this way:

The cross-sectional area of a via should have at least the same cross-sectional area as the conductor or be larger than the conductor coming into it. If the via has less cross-sectional area than the conductor, then multiple vias can be used to maintain the same cross-sectional area as the conductor.

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Simplify the stackups and make impedance and other measurements easier.

As many as seven different impedances are called out in various design specifications. Among these are:

  • 33Ω for Rambus memory
  • 50Ω for most high-speed logic
  • 65Ω for the PCI bus
  • 72-75Ω for analog circuits
  • 85Ω differential for PCIExpress (42.5Ω single-ended)
  • 95Ω differential for USB (47.5Ω single-ended)
  • 100Ω differential impedance for most high-speed Internet links (50Ω single-ended)

Successfully designing a PCB with more than one of these impedances can be difficult, if not impossible. The main challenge is designing a PCB stackup that has enough routing room for all the traces of each impedance while maintaining a manufacturable, economical product. A design that is all one impedance would be of great value. If so, what impedance would be the best? Here we address this topic.

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PCBAA's executive director lauds recent funding wins but says the heavy lifting remains.

Year-end is typically not the time when big announcements are made, but the news came fast and furious in November as TTM Technologies and Calumet Electronics both announced plans for new factories. Coupled with the opening of Schweitzer Engineering Laboratories' new fab in Idaho and the not-so-secret plant Starlink is building in Austin, one would have to return to early 2001 to see this level of PCB construction in the US.

All this new activity happily coincides with the efforts of the Printed Circuit Board Association of America. The fledgling trade group, which was founded in 2021 to advance US domestic production of PCBs and base materials, has been rallying federal legislators for attention – and funding – to ensure an onshore supply chain for domestic electronics.

We spoke with PCBAA executive director David Schild in late November on the PCB Chat podcast on the latest legislative and industry developments. Excerpts:

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