TC350 vs 92ML | Thermal RF Laminate Compared

TC350 vs 92ML: Which Thermal RF Laminate Should You Use?

Rogers TC350 offers a dielectric constant (Dk) of 3.50 and thermal conductivity of 1.00 W/m·K, while Arlon 92ML provides a lower Dk of 3.00 with a higher thermal conductivity of 2.00 W/m·K. TC350 is a thermoset ceramic-filled laminate that processes like FR-4; 92ML is a polyimide/ceramic composite designed for multilayer thermal management. The right choice depends on whether your priority is RF loss performance, thermal spreading, or multilayer integration.

Head-to-Head Property Comparison

The table below uses published datasheet values. Where a property is frequency-dependent, the test frequency is noted.

If you are comparing other RF laminate alternatives, the gap between these two materials is unusually clear: TC350 wins on electrical loss, 92ML wins on thermal conductivity and multilayer stackup flexibility.

Thermal Conductivity: Why the 2× Difference Matters

At 2.00 W/m·K, Arlon 92ML conducts heat through the dielectric at twice the rate of TC350’s 1.00 W/m·K. For a GaN power amplifier dissipating 10 W through a 20 mil (0.51 mm) dielectric layer over a 1 cm² footprint, the steady-state temperature rise across the dielectric is roughly ΔT = P × t / (k × A). With 92ML that gives about 2.5 °C; with TC350 it doubles to about 5 °C. That 2.5 °C difference compounds when multiple stages are stacked or ambient temperatures are high.

Use the tool below to compare thermal conductivity between TC350, 92ML, and other candidates in your stackup:

After entering your layer thickness and power dissipation, look at the temperature delta column. If the dielectric contributes more than 10 °C to your thermal budget, 92ML’s higher conductivity may be the deciding factor. If the delta is under 5 °C, TC350’s lower loss tangent likely delivers more system-level benefit by reducing PA drive requirements.

For designs that need even higher thermal conductivity—above 2 W/m·K—consider the comparison between TC350 and RT/duroid 6035HTC, which reaches 1.44 W/m·K but in a PTFE system, or move to ceramic-based substrates like alumina or aluminum nitride.

RF Loss Performance

TC350’s dissipation factor of 0.0020 at 10 GHz is genuinely low for a thermally enhanced laminate—comparable to RO4003C. Arlon 92ML’s Df of 0.0040 is respectable but double that figure. In practical terms, a 50 Ω microstrip on TC350 at 10 GHz and 50 mil trace length will have roughly half the dielectric loss of the same line on 92ML.

This matters most in:

• Radar T/R modules where cumulative insertion loss across feed networks degrades noise figure.
• Power amplifier combiners where loss converts directly to heat, partially negating 92ML’s thermal advantage.
• High-order filter networks where Q-factor is proportional to 1/Df.

At frequencies below 2 GHz, the loss difference between 0.0020 and 0.0040 is often negligible in short RF paths, and 92ML’s thermal performance dominates the trade-off. Above 6 GHz, TC350’s loss advantage becomes increasingly significant.

If loss is your primary concern and thermal management is secondary, standard Rogers hydrocarbon laminates like RO4350B or RO4003C may be more cost-effective than either TC350 or 92ML.

Processability and Multilayer Stackups

TC350: FR-4-Like Processing

TC350 is a thermoset ceramic-filled material that drills, plates, and laminates with standard FR-4 equipment. It does not require the sodium or plasma etch surface preparation that PTFE laminates demand. Standard oxide or oxide-alternative bonding treatments work. This makes TC350 attractive for shops without specialty RF laminate experience.

The limitation is multilayer integration. TC350 bonds best in hybrid stackups—typically as a core paired with standard prepreg or Rogers prepreg layers. Building a six-layer all-TC350 board is possible but uncommon, and the thicker available cores (30–60 mil) make thin multilayer builds impractical.

92ML: Native Multilayer Material

Arlon 92ML was designed from the start as a multilayer-compatible thermal laminate. Its polyimide matrix bonds with standard polyimide prepregs (like Arlon 91ML or other thermally conductive prepreg systems) using conventional lamination cycles. Cores as thin as 4 mil (0.10 mm) allow 8- to 12-layer builds with tight overall thickness control.

The trade-off is that polyimide processing requires higher lamination temperatures (around 220–250 °C) and longer press cycles than epoxy-based systems. Fabricators experienced with polyimide flex or rigid-flex will find 92ML familiar; those accustomed only to FR-4 may face a learning curve.

Thermal Cycling and Reliability

The z-axis CTE difference—30 ppm/°C for TC350 versus 50 ppm/°C for 92ML—directly affects plated through-hole reliability under thermal cycling. A higher z-CTE means more barrel expansion per cycle, accelerating fatigue cracking. For designs that see wide temperature swings (automotive radar, outdoor base stations, aerospace), TC350’s lower z-CTE provides a meaningful reliability margin.

Use this tool to plan your thermal cycling test based on your expected operating range and the laminate’s CTE:

Enter your minimum and maximum operating temperatures and the number of expected field cycles. If the tool indicates more than 500 equivalent stress cycles at a ΔT above 150 °C, pay close attention to via design: use via-in-pad with fill-and-cap, or back-drilled vias, to reduce the stressed copper column length. With 92ML’s 50 ppm/°C z-CTE, this becomes critical for boards thicker than 62 mil (1.57 mm).

Both materials survive standard Pb-free reflow profiles (peak 260 °C for 10 seconds), but TC350’s Td above 500 °C gives additional margin for rework cycles—an advantage in prototyping and low-volume production.

Typical Application Mapping

Cost and Availability Considerations

Neither TC350 nor 92ML is a commodity material. Both sit in a specialty niche and carry lead times of 4–8 weeks for non-standard thicknesses. Qualitatively:

• TC350 is manufactured by Rogers Corporation and benefits from Rogers’ broad distribution network. Panel sizes follow standard Rogers formats (12 × 18 in or 18 × 24 in). Pricing is moderate for a specialty laminate—below PTFE grades like RT/duroid 6035HTC but above standard RO4000 series.
• 92ML is an Arlon (now part of Rogers’ Arlon product line) material. Availability can be tighter outside North America. Its polyimide prepreg system (91ML) must be sourced alongside the core, adding a procurement step.

For teams evaluating broader material alternatives, the Rogers vs Arlon brand comparison covers the full portfolio overlap between these two families.

Design Guidance: Choose TC350 When… Choose 92ML When…

Choose TC350 when:

• Your design is 1–2 layers and the RF path is the critical performance axis.
• Operating frequency is above 6 GHz and insertion loss budget is tight.
• Your fabricator is experienced with FR-4-like thermoset processing but not polyimide.
• Wide temperature cycling (−55 °C to +125 °C) demands low z-axis CTE.

Choose 92ML when:

• You need 4+ layers with thermally conductive dielectric throughout the stackup.
• Heat dissipation through the board is the dominant design constraint.
• Operating frequency is below 6 GHz and the RF path is short enough that Df = 0.004 is acceptable.
• Your fabricator has polyimide multilayer capability and you need thin cores (4–10 mil).

Frequently Asked Questions

Can TC350 and 92ML be used in the same hybrid stackup?

It is technically possible but rarely done. TC350 is a thermoset and 92ML is polyimide-based, so their lamination profiles differ. A more common hybrid pairs TC350 with standard FR-4 or Rogers RO4000 prepreg, or 92ML with Arlon 91ML prepreg. Mixing resin systems introduces CTE mismatch risk at the bond interface.

What is the maximum frequency for 92ML?

Arlon rates 92ML’s Dk and Df at 10 GHz. It has been used successfully in designs up to X-band (8–12 GHz), but above 10 GHz the 0.0040 Df starts to impose meaningful insertion loss. For Ka-band and above, TC350 or a dedicated low-loss PTFE laminate is preferable.

Does TC350 require special via plating?

No. TC350 drills cleanly and plates with standard electroless copper processes. No desmear issues have been reported with the ceramic-filled thermoset matrix. This is one of its key advantages over PTFE-based thermal laminates, which require IPC-6012-compliant surface preparation steps like sodium etch or plasma treatment.

How do I verify Dk on incoming material?

Use a split-post dielectric resonator (SPDR) or a clamped stripline resonator per ASTM D2520 at your target frequency. Both Rogers and Arlon publish Dk vs. frequency curves on their datasheets; incoming inspection should confirm Dk within the stated tolerance (±0.05 for both materials).