PCB Materials

Rogers 4350B PCB Laminate

The industry-standard RF laminate: Dk 3.48, Df 0.0037 at 10 GHz.

Rogers RO4350B is a glass-reinforced hydrocarbon/ceramic laminate engineered for RF and microwave circuit boards. With a dielectric constant of 3.48 ±0.05 at 10 GHz and a dissipation factor of 0.0037 at 10 GHz, Rogers 4350B delivers low-loss performance that standard FR-4 cannot approach at frequencies above 1 GHz — while remaining compatible with standard FR-4 fabrication processes. This combination of RF performance and manufacturing simplicity has made RO4350B the most widely specified RF laminate in the industry.

Key electrical properties

The stable dielectric constant of Rogers 4350B across temperature and frequency is what distinguishes it from organic FR-4 laminates. FR-4 Dk varies by 5-10% depending on resin content, glass style and measurement frequency, making precise impedance control difficult above a few hundred MHz. Rogers 4350B maintains Dk within ±0.05 across its operating range, enabling repeatable impedance-controlled microstrip and stripline designs from UHF through Ku-band.

The low dissipation factor translates directly to lower insertion loss per unit length. At 10 GHz, a 50-ohm microstrip on RO4350B loses approximately 0.6-0.8 dB per inch, compared to 1.5-2.5 dB per inch on standard FR-4. For a 3-inch trace, that difference — 2 dB versus 7 dB — can determine whether a receiver front end meets its noise figure budget.

The thermal coefficient of dielectric constant (TCDk) is +50 ppm/°C, which is significantly better than FR-4 (typically +200 to +400 ppm/°C). This stability means that filter center frequencies, coupler coupling ratios and antenna return loss shift less with temperature on Rogers 4350B than on FR-4, reducing the need for temperature compensation circuitry.

Typical applications

Rogers 4350B is specified across a range of RF and microwave applications. Automotive radar at 77 GHz uses RO4350B for the antenna feed network and distribution layer, though the antenna elements themselves often require even lower-loss substrates. Base station power amplifier matching networks, cellular filter banks and GPS/GNSS antenna substrates use 4350B for its balance of loss, cost and processability. Satellite communication LNBs, point-to-point radio links and test equipment also commonly specify this laminate.

In mixed-signal designs, Rogers 4350B is frequently used in hybrid stackups where the RF signal layers use RO4350B while the digital control and power layers use standard FR-4. This hybrid approach provides RF performance where it matters while controlling total material cost.

Fabrication compatibility

Unlike PTFE-based laminates that require specialized drilling, plating and handling procedures, Rogers 4350B processes on standard FR-4 fabrication equipment. Standard mechanical drilling, copper plating, solder mask application and surface finishing all work without process modifications. This compatibility means that Rogers 4350B boards can be manufactured by any facility equipped for FR-4 production — without the lead time premium and limited source list associated with PTFE processing.

AstroPCB stocks Rogers 4350B in standard thicknesses (6.6 mil, 10 mil, 20 mil, 30 mil, 60 mil) and builds both all-Rogers and hybrid FR-4/Rogers stackups. Controlled impedance to ±8% is standard on all RO4350B builds.

Rogers 4350B vs Rogers 4003C

Rogers 4003C (Dk 3.38, Df 0.0027 at 10 GHz) offers slightly lower loss than 4350B but is more expensive and available in fewer thicknesses. For most applications below 20 GHz, the performance difference between 4350B and 4003C is marginal compared to other loss contributors (copper roughness, connector transitions, via discontinuities). 4350B is the default recommendation unless link budget analysis shows that the additional 0.001 Df reduction of 4003C is needed to close the margin.

Request a Rogers 4350B PCB quote

Upload your design files and specify Rogers RO4350B as the laminate. Include impedance targets and any hybrid stackup requirements. The engineering team will confirm material availability, build the stackup and return a quotation.

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