RO4350B vs AD350A | Full Parameter Comparison

RO4350B vs AD350A: Which Thermoset Laminate Wins?

Rogers RO4350B and Arlon AD350A are both thermoset, ceramic-filled hydrocarbon laminates designed to process on standard FR-4 equipment while delivering RF-grade performance. RO4350B offers a dielectric constant (Dk) of 3.48 ± 0.05 at 10 GHz with a dissipation factor (Df) of 0.0037, whereas AD350A targets a Dk of 3.50 ± 0.05 at 10 GHz with a Df of 0.0035. The two materials are close enough in electrical specs to be evaluated as alternatives, yet they differ meaningfully in thermal expansion, moisture absorption, availability and cost structure.

This comparison walks through every parameter that matters when choosing between RO4350B and AD350A for RF, microwave, antenna and radar boards. If you are evaluating multiple brands side by side, the RF laminate comparison tools on this site cover dozens of head-to-head matchups.

Core Electrical Parameters

The electrical starting point for any RF laminate decision is the Dk/Df pair, its stability over frequency and temperature, and how tightly the manufacturer controls it lot to lot.

On paper, the Dk and Df values are nearly interchangeable. The practical difference is in the supporting data: Rogers publishes detailed Dk vs. frequency curves up through 40 GHz and beyond, which makes EM simulation correlation straightforward. Arlon’s published data for AD350A is typically limited to 10 GHz, so designers working above 20 GHz may need to request extended characterization or run their own resonator tests.

Thermal and Mechanical Properties

Thermal expansion mismatch drives solder-joint reliability in surface-mount assemblies and via integrity in multilayer builds. Both materials use ceramic fillers to pull CTE closer to copper, but the numbers are not identical.

RO4350B’s lower z-axis CTE (32 vs. 40 ppm/°C) is significant for boards with many plated through-holes or blind/buried vias subjected to lead-free reflow (peak ~260 °C). A 25 % higher z-CTE increases barrel fatigue risk after multiple thermal cycles, so AD350A boards with dense via fields should be validated with IPC-TM-650 thermal stress testing. The higher thermal conductivity of RO4350B (0.69 W/m·K) also helps in power amplifier applications where heat needs to spread away from active devices.

Fabrication and Processing

Both RO4350B and AD350A were engineered to be processed with standard FR-4 epoxy tooling—no PTFE-specific handling, no sintering, no sodium-etch surface prep. This is the main reason this class of thermoset hydrocarbon laminates became popular: they cut fabrication cost and cycle time compared to traditional PTFE materials.

Key Processing Similarities

• Standard drill bits and routing parameters (no special carbide grades required)
• Compatible with oxide or oxide-alternative inner-layer treatments
• Lamination press cycles similar to high-Tg FR-4
• Solder mask and surface finish options identical to FR-4 builds

Where They Diverge

• Prepreg system: RO4350B pairs with Rogers RO4450F prepreg (Dk 3.52, Df 0.004 at 10 GHz). AD350A uses Arlon’s own 45N or compatible prepreg. Mixing brands in a hybrid stackup requires careful Dk matching and lamination compatibility testing.
• Panel sizes: RO4350B is stocked in 12 × 18 in (305 × 457 mm) and 18 × 24 in (457 × 610 mm) panels. AD350A availability may be limited to fewer standard sizes; confirm with your laminate distributor before committing a panel layout.
• Thickness range: RO4350B is available from 6.6 mil (0.168 mm) to 60 mil (1.524 mm). AD350A covers a similar range but some thicknesses are made to order, adding lead time.

If you are comparing Rogers against the broader Arlon portfolio—including PTFE-based materials like AD255A or CLTE-series—the Rogers vs Arlon brand comparison covers the full picture.

Arlon Material Selection

Arlon offers a wide family of laminates spanning low-Dk PTFE to high-Dk ceramic-filled thermosets. If AD350A’s specs are close but not quite right—perhaps you need a lower Dk or a different CTE profile—use the selector below to filter Arlon materials by your design requirements and see where each grade fits.

For example, entering a target Dk of 3.50 and a maximum Df of 0.004 will surface AD350A alongside any other Arlon grades that meet those criteria. From there, you can compare CTE, thickness availability and pricing tiers to narrow the field. If Taconic is also on your shortlist, see how their line stacks up in the Taconic vs Arlon comparison.

Supply Chain, Availability and Cost

Material availability is often the deciding factor in production programs, and this is where RO4350B holds a clear advantage.

RO4350B Supply Position

• One of the most widely stocked RF laminates globally; carried by major distributors (Richardson RFPD, Digi-Key, Mouser) and most specialty PCB fabricators.
• Multiple manufacturing sites (Rogers operates plants in the US, Belgium and China), providing geographic redundancy.
• Standard lead time for stock thicknesses: typically 1–3 weeks.

AD350A Supply Position

• Arlon (now part of AGC) has a smaller distribution footprint. AD350A may not be stocked by all RF laminate distributors.
• Lead times for non-standard thicknesses can reach 6–10 weeks.
• Unit pricing is generally comparable to or slightly below RO4350B for equivalent thicknesses, but volume pricing depends heavily on negotiated contracts.

In cost-sensitive programs where AD350A’s electrical specs are adequate, the material can offer modest savings—especially at volume with a direct supply agreement. However, the qualification effort and potential supply-chain risk should be weighed against that saving. A second-source strategy works best when you validate both materials on the same test coupon design and confirm that insertion-loss and impedance results fall within your tolerance window.

Design and Simulation Considerations

Accurate EM simulation depends on having validated material models. Rogers provides free Microwave Impedance Calculator tools and Dk/Df tables that plug directly into tools like HFSS, CST and ADS. For AD350A, you will likely need to build your own material model from the datasheet values and verify it against measured S-parameter data on a test board.

This matters most above 10 GHz, where small Dk errors translate to meaningful frequency shifts in filters, couplers and antenna elements. A 0.02 error in Dk at 24 GHz shifts a patch antenna resonance by roughly 50–70 MHz—enough to push the passband edge outside the ISM band.

When comparing RO4350B against other Rogers alternatives, the RO4350B vs RO4003C analysis and the I-Tera MT40 vs RO4350B comparison provide useful context on where each material’s sweet spot lies.

Typical Application Fit

Choose RO4350B When

• You need frequencies above 20 GHz and require well-characterized Dk/Df curves for accurate simulation.
• The design has dense via fields or will undergo multiple reflow cycles (lower z-CTE reduces barrel-crack risk).
• Supply-chain resilience and short lead times are critical (production ramp, automotive PPAP).
• Power amplifier stages need better thermal spreading (0.69 vs. 0.50 W/m·K).
• You are building hybrid multilayers with RO4450F prepreg and need a matched Dk system.

Choose AD350A When

• Your operating frequency is at or below 10 GHz, where both materials are equally well characterized.
• Cost pressure is significant and you have the lead time to qualify an alternative.
• You are already using other Arlon materials (e.g., CLTE-XT for outer layers) and want to stay within one vendor’s prepreg ecosystem.
• The design is a lower-layer-count board (2–4 layers) with moderate via density, reducing z-CTE concerns.
• Slightly lower Df (0.0035 vs. 0.0037) matters for a loss-budget-critical link—though the real-world difference is marginal at most frequencies.

Head-to-Head Summary Table

Frequently Asked Questions

Can I swap AD350A for RO4350B without re-simulating?

At frequencies below about 6 GHz, a direct swap often works if you account for the 0.02 Dk offset (3.50 vs. 3.48). Above 10 GHz, you should re-run impedance and coupling simulations because even small Dk differences shift filter center frequencies and antenna match. Always verify with a test coupon.

Is AD350A UL recognized?

AD350A carries UL 94 V-0 recognition, as does RO4350B. Both meet the flammability requirements of IPC-4101 slash sheets for thermoset non-woven laminates. Confirm the specific UL file number with Arlon/AGC for your target construction.

Which material is better for automotive radar at 77 GHz?

Neither RO4350B nor AD350A is the first choice at 77 GHz. At millimeter-wave frequencies, lower-Dk, lower-loss materials like RO3003 (Dk 3.00, Df 0.0010) dominate. See the RO3003 vs Astra MT77 comparison for the leading 77 GHz candidates.

Does AD350A support sequential lamination for HDI builds?

Yes, AD350A can be used in sequential lamination cycles, though you must verify the reflow survivability of earlier lamination bonds given the 40 ppm/°C z-CTE. RO4350B’s lower z-CTE provides more margin for builds requiring three or more lamination cycles.

What is the maximum operating frequency for these materials?

Both can be used up to at least 30–35 GHz in practice. RO4350B has published performance data and proven designs at 24 GHz (ISM band) and 28 GHz (5G n257/n258). AD350A is commonly used through Ku-band (~18 GHz), with less published evidence at higher bands.