Frank — Senior Electronics Engineer, USA
Choosing the right substrate is one of the first engineering decisions that determines RF performance, thermal robustness, and manufacturability.
Rogers materials are engineered laminates and prepregs tailored for RF, microwave, and high-frequency designs; they provide a stable dielectric constant (Dk), low loss tangent, and thermal and mechanical behavior that differs significantly from conventional FR-4.
In my work as a senior electronics engineer I typically select Rogers laminates when signal loss, impedance stability across frequency, or elevated operating frequencies make standard epoxy-glass impractical.
This article explains the principal Rogers families (RO3000 and RO4000/RO4350B), summarizes the electrical and thermal properties engineers must check, compares Rogers to FR-4 for common use cases, and offers practical design and fabrication guidance.
My goal is practical: to give engineers the technical criteria and a concise checklist for deciding when Rogers substrates are the right choice. Examples, datasheets, and measurement tips follow in the article below.
1 — What are “Rogers” materials?
“Rogers” refers to a family of engineered circuit-material products from Rogers Corporation designed for RF, microwave and high-frequency digital circuitry. These laminates and prepregs are formulated to deliver a controlled dielectric constant and lower dissipation (loss) than typical FR-4 epoxies, and they are offered in several series tuned to different frequency and processing needs. Designers use Rogers when broadband impedance stability, low insertion loss, and consistent electrical behaviour with temperature are priorities.
2 — Key Rogers families engineers commonly encounter
RO3000® series (RO3003, etc.): engineered for dielectric stability over temperature and frequency; commonly used in mmWave, automotive radar and 5G front-end designs where Dk stability is critical.
RO4000®/RO4350B® series: ceramic-filled, process-compatible laminates that give low loss and tight Dk control while being easier to process than PTFE-based materials; RO4350B is widely used where a balance of performance and fabrication ease is required.
When you pick a family, look at the published Dk vs. frequency curves, loss tangent (dissipation factor), and the manufacturer’s guidance for thickness-dependent Dk tolerance.
3 — Electrical properties that matter (and how to read them)
For RF engineering the most important material specs are:
- Dielectric constant (Dk or εr): determines guided wavelength and the characteristic impedance of microstrip/coplanar traces. Tight Dk control reduces impedance uncertainty and helps matching-network predictability. Rogers materials often publish Dk values with narrow tolerances and frequency stability plots.
- Dissipation factor / loss tangent (tan δ): lower values reduce insertion loss at RF and microwave frequencies — critical for antenna feeds, filters, and long microstrip runs. RO4350B and related laminates show much lower loss than typical FR-4 at GHz frequencies.
- Temperature coefficients and moisture absorption: stable Dk across temperature and low moisture uptake keep RF behaviour predictable in the field (important for aerospace, automotive, and outdoor telecom equipment).
- When reading a datasheet, prefer the manufacturer’s IPC-based test references (IPC-TM methods) and the plotted curves, single-number Dk at one frequency is not enough for broadband designs.
4 — Mechanical and thermal considerations
Rogers laminates typically provide improved thermal conductivity, higher Tg (glass transition), and lower Z-axis CTE compared with many FR-4 mixes used at high frequencies. These mechanical/thermal metrics affect via reliability, plated-through-hole processing, and soldering profiles. For power-handling or high-temperature assembly, check Tg, Td (decomposition), and CTE values on the datasheet and discuss acceptable lead-free reflow temperatures with your board house.
5 — How Rogers differs from FR-4
In practical engineering terms:
- Signal loss: Rogers materials usually show significantly lower loss at GHz frequencies than standard FR-4, which matters for long RF traces and mmWave paths.
- Dk stability: Rogers laminates are formulated to keep Dk stable across frequency and temperature ranges; FR-4 Dk can vary more with frequency and moisture content.
- Process and cost: some Rogers materials (e.g., RO4350B) are designed to be processed on standard epoxy-glass lines, reducing handling complexity compared with PTFE-based substrates — but they are still typically more expensive than commodity FR-4. Choose based on electrical need, not brand preference.
6 — Design and fabrication notes (what to tell your board house)
Specify the exact Rogers material and thickness in the fabrication notes (e.g., RO4350B, 0.031" core) and request the recommended stackup for your target single-ended or differential Z0.
Include impedance test coupons and identify them on the fabrication panel so you can get measured data back with the shipment.
Verify via and finishing processes: some high-frequency stackups prefer specific via treatments or bonding sheets; confirm whether the vendor uses standard via plating processes compatible with the selected Rogers material.
For quick prototypes, many engineers cross-check manufacturer datasheets and then consult online fabricator guidance; for example, you can review prototyping options and fabricator-controlled-impedance notes at jlcpcb.
7 — Typical applications where Rogers is the right choice
Antennas and feeds where low insertion loss and stable phase are essential.
RF/microwave filters and matching networks where predictability across a band reduces tuning iterations.
Automotive radar and mmWave (e.g., 77 GHz/5G mmWave) where Dk stability and low dispersion matter.
High-performance microwave modules in telecom, satellite, and defense equipment where environmental stability and low loss are critical.
8 — Measurement and validation checklist (what I measure in the lab)
Confirm coupon Dk and Z0 using a VNA or impedance test fixtures and compare measured values to the supplier’s report.
Check insertion loss on representative traces or transmission lines across the intended band.
Thermal and reflow verification: run a small assembly through your solder profile to confirm no delamination and acceptable surface finish behaviour.
Document the results and keep the test coupons with the user-side acceptance criteria for future production lots.
9 — Procurement and cost considerations
Rogers laminates cost more than commodity FR-4 and sometimes require minimum order sizes for cores or prepregs. For a prototype-first approach, order a small sample run with test coupons to validate electrical performance before committing to a larger production order. For supply-chain sensitive programs, verify lead times and alternative laminate grades in case of material allocation constraints.
Conclusion
When your design requires predictable impedance, low RF loss, and stable behaviour across temperature and moisture conditions, Rogers materials are often the correct technical choice. Use the manufacturer’s datasheets and property tools, request impedance test coupons, run small validation builds, and balance cost versus RF performance. This approach reduces debugging time and increases first-pass yield for RF and microwave products.
Disclaimer: This material is provided for educational purposes and reflects practical engineering experience and public datasheets; it is not sponsored or paid content.
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