As a Rogers PCB supplier with over a decade of experience working directly with aerospace, 5G infrastructure, and medical device clients, I’ve seen first-hand how via reliability issues can derail even the most carefully designed high-frequency circuits. Rogers materials like RO4003, RO4350B, and Rogers ULTRALAM are chosen for their low dielectric constant (Dk), low loss tangent, and ability to perform at GHz frequencies—traits that make them irreplaceable for advanced applications. But their unique chemical and physical properties also create challenges that generic FR-4 PCBs rarely face. Today, I want to break down the most common via reliability issues our team troubleshoots, why they happen, and what we do to mitigate them for our clients. Rogers PCB
Let’s start with the basics: a via is a small plated-through hole (PTH) that connects two or more conductive layers in a PCB. For Rogers boards, vias are critical because high-frequency signals travel between layers at specific impedance; a failing via can introduce signal loss, impedance mismatch, or even total circuit failure—especially in systems like 5G base stations that run 24/7 in extreme temperatures and humidity. The first big issue we see is barrel cracking, and it’s far more prevalent in Rogers PCBs than in FR-4. Why? Rogers laminates are inherently more rigid and have a different coefficient of thermal expansion (CTE) than copper. Copper’s CTE is around 17 ppm/°C, while standard FR-4 is roughly 13–18 ppm/°C, so they expand and contract at almost the same rate during thermal cycling (like manufacturing reflow or end-use temperature swings). But Rogers materials? Their CTE in the z-axis (the direction perpendicular to the board surface, which is where vias run) is a fraction of copper’s—often as low as 5–7 ppm/°C for RO4003. That huge mismatch means when the board heats up, the copper barrel tries to expand more than the surrounding laminate; when it cools, the copper shrinks faster, creating shear stress at the interface between the barrel and the laminate. Over hundreds of thermal cycles (standard qualification requires 1000 cycles from -55°C to 125°C), that stress adds up, leading to tiny cracks in the copper barrel or delamination between the barrel and the laminate wall. Last year, we had a client in satellite communications come to us with 12% of their boards failing thermal shock testing—turns out they used a standard via drilling process designed for FR-4 on their RO4350B boards, which only worsened the stress.
Another common pitfall is voids in the via plating. Voids are small pockets of air or unplated copper inside the via barrel, and they’re not just a cosmetic issue—they increase signal resistance and can cause open circuits over time. The problem here ties directly to Rogers’ surface chemistry. Unlike FR-4, which has a high glass transition temperature (Tg) and a slightly porous surface that accepts plating well, Rogers laminates are non-polar and have a very smooth surface. When we drill a via, the surface of the laminate inside the hole is hydrophobic, so the acidic copper plating solution doesn’t spread evenly—instead, it can form bubbles or thin spots before plating fully covers the wall. We’ve seen this cause 3–5 dB of insertion loss in 28 GHz 5G antenna arrays, which is enough to drop a cell signal in dense urban areas. A client in medical wearables once missed a regulatory compliance deadline because their vias had micro-voids that caused intermittent signal loss in a cardiac monitor; we traced the issue to their fabricator using the same pre-treatment process they used for FR-4, which didn’t etch enough of the Rogers surface to create a good adhesion base.
Then there’s what we call “cap leakage” in blind and buried vias, which are super popular for high-density Rogers PCBs because they save space and reduce signal path length. Blind vias connect an outer layer to an inner layer, and buried vias connect two inner layers, instead of running all the way through the board. The issue here is that Rogers materials have very low moisture absorption—good for high-frequency performance, but bad for via reliability. When we cap a via (fill the top with solder mask or resin to protect it), we rely on the cap to form a hermetic seal. But because Rogers doesn’t absorb moisture, any residual moisture or plating by-product inside the via can’t escape. Over time, that moisture seeps past the cap, or the cap itself delaminates from the Rogers surface, leading to corrosion of the copper barrel. We had a defense client last year whose drone PCBs failed after 6 months of field testing in a humid coastal environment; the cause was tiny pinholes in the via caps that let saltwater penetrate, corroding the barrels until they broke. FR-4 absorbs moisture, so even small gaps would let moisture spread evenly, but on Rogers, it stays concentrated directly on the via wall, accelerating corrosion.
Wait, let’s not forget via impedance mismatch, which is a reliability issue that’s easy to overlook but just as damaging. For high-frequency signals (above 10 GHz), a via isn’t just a conductive hole—it’s a component with its own impedance. Rogers materials’ low Dk means that the impedance of a via is lower than it would be in FR-4, so if the via isn’t designed to match the transmission line impedance (usually 50 ohms for most RF circuits), you get signal reflection. That reflection can cause distortion, which leads to data errors in 5G or radar systems, and over time, repeated reflection can degrade the via’s structural integrity by creating tiny cracks in the copper barrel. We worked with a radar system integrator who had their boards fail field testing because their vias were designed for FR-4, so the impedance was 30 ohms—enough to cause a 12% signal loss, which made the radar unable to detect targets at the expected range.
So how do we, as a Rogers PCB supplier, fix these issues? First, we adjust our drilling and plating processes specifically for Rogers. Instead of using standard drill bits, we use diamond-coated bits that create a slightly rougher via wall surface, which helps the plating solution adhere better. For barrel cracking, we tune our thermal profiles during manufacturing: we ramp up the temperature slower during reflow to give the copper and laminate time to expand together, and we add a stress relief bake after plating to reduce residual stress. For voids, we use a modified pre-treatment process called plasma etch, which uses oxygen plasma to etch a microscopic texture into the Rogers surface without damaging the laminate, so the plating solution spreads evenly and eliminates micro-voids. For blind and buried vias, we use a resin cap with a CTE matched to Rogers, so it expands and contracts at the same rate as the laminate, reducing delamination risk. We also run in-process testing at every stage: after drilling, we inspect via walls with a microscope; after plating, we do a continuity test; and before shipment, we run thermal cycling and insertion loss testing specific to Rogers materials.
What’s most important to understand is that via reliability in Rogers PCBs isn’t just a manufacturing issue—it’s a design issue too. We work closely with our clients during the design phase to adjust via size, spacing, and plating thickness to match their specific application. For example, a satellite PCB that will experience extreme temperature swings needs thicker copper barrels and larger via size to reduce stress, while a 5G antenna array that needs high density might use laser-drilled blind vias with a matched CTE cap.
At the end of the day, Rogers materials offer unmatched performance for high-frequency and high-reliability applications, but their unique properties mean that standard PCB processes simply won’t cut it. If you’re working on a project that requires Rogers PCBs and you’ve seen via reliability issues slowing you down, or if you’re just looking for a partner that understands the nuances of working with these materials, we’re here to help. We’ve supported clients across aerospace, telecom, medical, and defense, and we can walk through your design, test for potential issues, and deliver boards that meet your performance and reliability requirements.
FR4 PCB References:
- Johnson, H., & Graham, M. (2003). High-Speed Signal Propagation: Advanced Black Magic. Prentice Hall.
- Rogers Corporation. (2022). Design and Manufacturing Guide for Rogers High-Frequency Laminates. Rogers Corporation.
- IPC-6012. (2021). Qualification and Performance Specification for Rigid Printed Boards. IPC Association Connecting Electronics Industries.
- Bhattacharya, S., & Chatterjee, S. (2019). “Thermal Stress Analysis of Plated Through Holes in High-Frequency PCB Laminates”. IEEE Transactions on Components, Packaging and Manufacturing Technology.
Fastline Circuits Co., Limited
Fastline Circuits Co., Limited is one of the most professional rogers PCB manufacturers and suppliers in China. With abundant experience, we warmly welcome you to wholesale durable rogers PCB made in China here and get quotation from our factory. All customized products are with high quality and competitive price.
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