Flexible Thinking: Designing Flex Circuits for Dynamic Reliability
Global PCB Connections: Rigid-flex and Flexible PCBs—The Backbone of Modern Electronics
Happy’s Tech Talk #29: Bend-to-Install Semi-flex FR-4
Does Copper Pour on a Signal Layer Decrease Signal-To-Signal Isolation?
April 7, 2022 | Steve Hageman, Analog HomeEstimated reading time: 1 minute
Does putting a ground pour on PCB signal layers make the isolation better or worse? It can go either way, but with the proper knowledge and application, this technique will improve your designs.
In this article, I’ll discuss how to simulate trace-to-trace isolation with true electromagnetic simulation software. We’ll also cover a variety of rules of thumb that can help you stay away from trouble.
Fact or Fiction?
Recently an acquaintance told me, “I have heard that putting a copper pour on a signal layer between traces actually makes the isolation between the traces worse.” I grabbed one of my RF boards and said, “If that is so, then how do all these RF boards that I have done with co-planar waveguide over ground manage to function? They all have copper pours on the signal layer, and they work to very high frequencies.”
Since co-planar waveguide over ground (CPWG), which is essentially “pouring copper on a signal layer,” is used for a lot of RF work, and is proven to work for very high-performance RF circuits, how did this contradictory opinion catch on in the industry?
To investigate this, I used a one-inch section of 50-ohm microstrip consisting of an aggressor trace from ports 1 to 2 and a victim trace running in parallel from ports 3 to 4. I used typical values for the dimensions as might be on a real PCB. The trace width is 20 mils, with a spacing of 60 mils from center to center, over an FR-4 substrate, 9.5 mils thick, with a modeled Er of 4.4.
To read this entire article, which appeared in the March 2022 issue of Design007 Magazine, click here.
Share on:
Testimonial
"Advertising in PCB007 Magazine has been a great way to showcase our bare board testers to the right audience. The I-Connect007 team makes the process smooth and professional. We’re proud to be featured in such a trusted publication."
Klaus Koziol - atgSuggested Items
ACCM Unveils Negative and Near-zero CTE Materials for Large-Format AI Chips
04/21/2026 | Advanced Chip and Circuit MaterialsAdvanced Chip and Circuit Materials, Inc. (ACCM) has launched two new materials: Celeritas HM50, with a negative coefficient of thermal expansion (CTE) of -8 ppm/°C to offset the positive CTE and expansion of copper with temperature on circuit boards, and Celeritas HM001, with near-zero CTE and the low-loss performance needed for high-speed signal layers to 224 Gb/s and faster in artificial intelligence (AI) circuits.
Advanced Packaging for AI: Reliability Starts at the Cu/Cu/Cu Microvia Junction
04/20/2026 | Kuldip Johal, MKS' AtotechThe rapid growth of AI computing, from training clusters to inference at scale, is reshaping demand across the entire electronics supply chain. Advances in technology requirements, such as higher bandwidth, lower latency, and greater compute density, are driving the development of advanced packaging technologies and transforming the PCB industry across design, manufacturing, testing, and even architecture.
Volatile Metals Market Creates PCB Pricing Headache
04/20/2026 | Nolan Johnson, I-Connect007Market volatility for precious metals is very real. Financial organizations have reported elevated volatility, with record highs and steep corrections; in 2025 alone, gold has increased by over 60%, silver over 120%, and copper over 35%. Each is a critical raw material used in electronics manufacturing, where pricing is already fraught for business owners and their customers due to tariff uncertainty and a critical supply chain that resides mostly in China. The volatility of precious metals markets adds yet another layer of complexity for manufacturers, pushing up raw material costs.
Nortech Systems Launches Power over Fiber Technology Platform for EMI-Sensitive Applications
04/08/2026 | Globe NewswireNortech Systems Incorporated, a leading provider of design and manufacturing solutions for complex electromedical devices and electromechanical systems, has announced the launch of its Power over Fiber technology platform.
Flexible Thinking: Designing Flex Circuits for Dynamic Reliability
04/09/2026 | Joe Fjelstad -- Column: Flexible ThinkingFlex circuits flex. No surprises there. However, they are also very commonly designed into products because they are thin and offer consistent thickness and dielectric properties, attributes highly prized by present-day product designers of personal electronics. This would include smartphones and, increasingly, wearable electronics for medical monitoring and even fashion.