RF Laminate Thickness Chart | All Brands Reference

RF Laminate Thickness Chart: Quick Reference

Standard RF laminate thicknesses range from 5 mil (0.127 mm) for tightly coupled stripline cores up to 60 mil (1.524 mm) for rigid single-layer microstrip designs. The exact catalog of available thicknesses varies by material family—Rogers PTFE laminates offer the widest selection, while thermoset ceramic-filled grades and hydrocarbon blends have a narrower but still practical set. The tables below collect the most commonly stocked thicknesses across five major laminate brands so you can confirm availability before committing a stackup.

Why Laminate Thickness Matters in RF Design

Dielectric thickness is one of only four variables that set microstrip characteristic impedance (the others being trace width, copper weight, and Dk). A 1 mil error in a 10 mil core shifts impedance by roughly 3–5 Ω on a 50 Ω line, which is why laminate thickness tolerance deserves as much attention as the nominal value itself. Choosing a thickness that is actually manufactured—rather than interpolating between catalog entries—avoids minimum-order surcharges and lead-time surprises.

Thickness also controls coupling in broadside-coupled stripline filters, cavity depth in substrate-integrated waveguides, and the mechanical stiffness of the finished board. For a broader discussion of how frequency band drives the ideal overall board thickness, see the guide on how thick an RF PCB should be.

Rogers High-Frequency Laminates

Rogers Corporation publishes the most granular thickness menu in the industry. The table below covers the five families most frequently specified in microwave PCBs. All thicknesses are nominal dielectric only (no copper).

RO4350B at 10 mil is the single most popular RF core globally—it processes on standard FR-4 equipment, which keeps fabrication cost close to mainstream boards. For 77 GHz automotive radar front-ends, RO3003 at 5 mil is a common choice; its next-generation G2 variant tightens Dk tolerance to ±0.04. When high Dk is needed for miniaturized patch antennas, the RO4360G2 vs RO3010 comparison helps decide between a thermoset and a PTFE route.

For the full Rogers thickness and tolerance data, the Rogers RO4350B product page lists every panel size and thickness option with tolerance bands.

Isola High-Frequency Laminates

Isola’s Astra MT77 is gaining traction in 5G massive-MIMO antenna boards where a Dk of 3.00 and a loss tangent below 0.002 are needed at a lower price point than PTFE. I-Tera MT40 straddles the boundary between high-speed digital and RF; for a head-to-head with Rogers, see the I-Tera MT40 vs RO4350B comparison. Isola publishes detailed laminate data through their Astra MT77 product page.

Taconic High-Frequency Laminates

Taconic TLY-5 is a direct drop-in alternative to RT/duroid 5880 with nearly identical Dk/Df and thickness options, often at a shorter lead time for small-volume prototyping. RF-35 competes with RO4350B in the Dk ≈ 3.5 space and is popular for S-band radar and communications boards where moderate loss and standard processing are acceptable.

Panasonic MEGTRON and Felios

MEGTRON 7 is primarily a high-speed digital laminate, but its Df of 0.0015 at 10 GHz puts it firmly in RF territory for phased-array digital beamforming backplanes. Felios LCP (liquid crystal polymer) cores as thin as 1 mil (0.025 mm) serve flex and rigid-flex mmWave interconnects where traditional PTFE cannot bend.

Ventec RF Laminates

Ventec’s VT-47 and VT-870 are positioned as cost-effective alternatives to Rogers RO4000 series for designs below about 10 GHz. A deeper look at these families and their polyimide options is available in the Ventec RF laminate overview.

How to Read and Use This Chart

Nominal vs. Actual Thickness

Catalog thickness is nominal dielectric-only, measured before copper cladding is applied. A “10 mil” core with ½ oz copper on both sides ships at roughly 11.4 mil total (10 + 2 × 0.7 mil). Always confirm whether your EDA tool’s stackup editor expects dielectric-only or total laminate thickness; entering the wrong number shifts your impedance calculation.

Tolerance Classes

Most PTFE laminates carry ±1.0 mil or ±10 % (whichever is greater) per IPC-4101/4103 slash-sheet specifications. Thermoset hydrocarbon laminates like RO4350B are tighter at ±0.5 mil on thinner cores. A ±10 % swing on a 5 mil core is ±0.5 mil—enough to move a 50 Ω microstrip by 2–3 Ω. For production boards, request incoming inspection data or apply statistical process control to catch drift.

Stencil Thickness Selection for RF Assemblies

Once the laminate is chosen, the next thickness decision is the solder-paste stencil. For fine-pitch RF components such as QFN MMICs and 0201 bypass capacitors, stencil thickness directly affects solder volume and joint reliability. Enter your smallest pad pitch below to get a recommended stencil thickness.

A typical result: for a 0.5 mm pitch QFN on an RO4350B board, the tool recommends a 4 mil (0.100 mm) stencil. Going thicker risks bridging between the fine ground-paddle vias; going thinner starves the RF signal pads of solder, raising contact resistance at the MMIC ground transition. If your design mixes large power pads with fine-pitch RF, consider a step stencil with two thickness zones.

Conformal Coating Thickness on RF Boards

Harsh-environment RF assemblies—automotive radar modules, maritime antennas, defense electronics—often receive conformal coating. Coating thickness must be controlled because an extra 25 µm of acrylic or silicone over a microstrip trace shifts effective Dk and can detune filters and matching networks. Use the tool below to check recommended coating thickness ranges for your coating chemistry.

For a silicone conformal coat on a 24 GHz radar module, the tool typically suggests 50–75 µm. At 77 GHz, even that range can introduce measurable insertion loss; many designers opt for selective coating that avoids critical transmission lines entirely, protecting only the component bodies and solder joints. Always verify the coated-vs-uncoated S-parameter shift on a test coupon before committing to production.

Choosing the Right Thickness for Your Frequency Band

A useful rule of thumb: keep the dielectric thickness below λ/10 at the highest operating frequency to suppress surface-wave modes in microstrip. The table below translates that guideline into maximum recommended core thickness for several common bands.

At W-band (77 GHz automotive radar), only the thinnest cores—5 mil RO3003 or 5 mil RT/duroid 5880—keep surface waves under control while still being mechanically handleable in fabrication. Below 5 mil you generally transition to thin-film processes on alumina or fused silica.

Practical Tips When Specifying Laminate Thickness

• Check stock panels first. Rogers and Taconic maintain standard-stock thicknesses that ship in 1–2 weeks. Non-standard thicknesses are made-to-order with 6–10 week lead times.
• Match prepreg to core Dk. In multilayer RF stackups, a Dk mismatch between core and prepreg creates an impedance step at the bonding interface. Rogers publishes bondply (e.g., RO4450F) specifically matched to RO4350B cores.
• Account for pressed thickness. Prepreg resin flow during lamination can thin the dielectric by 10–20 % depending on copper pattern density. Your fabricator’s stackup table—not the raw prepreg datasheet—is the number to use in your impedance model.
• Document tolerances on the drawing. Call out dielectric thickness tolerance per IPC-6012 Class 3 or tighter if needed, and reference the RF PCB tolerance capability table to confirm what your fabricator can hold.

FAQ

What is the thinnest RF laminate available?

Panasonic Felios LCP cores are available down to 1 mil (0.025 mm). Among PTFE laminates, Rogers RT/duroid 5880 and RO3003 go down to 5 mil (0.127 mm). Below 5 mil, ceramic substrates (alumina, LTCC) are more common.

Can I get a custom thickness from Rogers?

Yes. Rogers accepts custom-thickness orders, but minimum order quantities typically start at 50–100 panels and lead times are 8–12 weeks. For prototyping, it is almost always faster to design around a standard catalog thickness.

Does laminate thickness affect insertion loss?

Indirectly. A thicker core requires a wider trace for the same impedance, which reduces conductor loss (lower current density). However, thicker substrates increase radiation and surface-wave loss at higher frequencies. The net effect depends on frequency, Dk, and copper roughness.

How do I convert mil to mm for laminate thickness?

1 mil = 0.0254 mm. Multiply the mil value by 0.0254. For example, 10 mil = 0.254 mm, 20 mil = 0.508 mm, 60 mil = 1.524 mm.

Is RO4350B available in 5 mil thickness?

Not as a standard catalog item. The thinnest standard RO4350B core is 4 mil (0.101 mm). If you need 5 mil with similar Dk, consider Isola Astra MT77 or Taconic RF-35, both of which stock a 5 mil option.