RO4350B vs S7136 | Which Laminate for Your RF PCB

RO4350B vs S7136: Quick Answer

Rogers RO4350B and Shengyi S7136 are both thermoset, glass-reinforced hydrocarbon laminates designed to process like FR-4 while delivering RF-grade dielectric performance. RO4350B has a Dk of 3.48 ± 0.05 and Df of 0.0037 at 10 GHz; S7136 targets a Dk of 3.48 ± 0.05 and Df of 0.004 at the same frequency. The practical difference is small on paper, but diverges in Dk tolerance consistency, lot-to-lot repeatability, supply chain and price—factors that often matter more than the headline numbers.

Key Electrical Properties Compared

The table below puts the two materials side by side using data from each manufacturer’s published datasheets. All values are at 10 GHz unless noted.

One mil equals 0.0254 mm. If you need to convert between mils, millimeters, ounces and microns while reading stackup specs, the converter below handles all common PCB units.

For example, a 10 mil (0.254 mm) core of either material is a common choice for tightly coupled stripline in sub-6 GHz designs. Entering “10 mil” returns 0.254 mm—handy when switching between a Rogers datasheet (imperial) and a Shengyi datasheet (metric).

Dielectric Loss: Does the 0.0003 Gap Matter?

At 10 GHz the difference in Df between RO4350B (0.0037) and S7136 (0.004) is roughly 0.0003. Whether that matters depends on the electrical length of your traces and the frequency of operation.

For a 50 mm microstrip at 5.8 GHz—typical Wi-Fi 6E front-end—the additional conductor and dielectric loss from S7136 adds approximately 0.03–0.05 dB compared with RO4350B. In most receive chains that is within noise-figure margin. At 24 GHz or 28 GHz, however, the same 50 mm trace sees the loss difference amplified roughly fourfold because dielectric loss scales with frequency. A 77 GHz automotive radar front-end would magnify it further, though at that frequency both materials are usually replaced by lower-loss options such as RO3003.

Rule of thumb: Below 10 GHz with moderate trace lengths (< 100 mm), S7136's extra loss is negligible. Above 15 GHz or in long feed networks, RO4350B's lower Df provides a measurable link-budget advantage.

Dk Tolerance and Lot-to-Lot Consistency

Both datasheets claim ± 0.05 on Dk. The practical difference is in how tightly each vendor holds that window across production lots. Rogers has decades of process control data on RO4350B and publishes a “design Dk” versus “process Dk” distinction, encouraging designers to use the process Dk (often measured by the clamped stripline method at Rogers) for impedance calculations.

Shengyi’s S7136 datasheets provide a single Dk value measured by the IPC-TM-650 split-post resonator method. Fewer published application notes exist, and independent third-party characterization data above 15 GHz is limited. If your design relies on tight impedance control (e.g., ± 5 % on a 50 Ω line in a phased-array feed network), request lot-specific Dk data from the laminate supplier and, ideally, run a test-coupon verification panel.

Processability and Fabrication

Both RO4350B and S7136 were engineered to be processed on standard FR-4 lamination and drilling equipment, which is a major reason each has gained traction over older PTFE-based materials. Key fabrication considerations:

• Drilling: Both use woven-glass reinforcement and thermoset resin, so standard carbide drill bits work. Hole-wall quality is comparable.
• Plating: Neither requires the sodium-naphthalene etch-back that PTFE laminates demand. Standard desmear and electroless copper processes apply.
• Lamination with FR-4: Hybrid stackups (RF layers on RO4350B or S7136, digital layers on FR-4) are common. Both materials bond well with standard no-flow or low-flow prepregs. Rogers offers RO4450F bonding film; Shengyi offers S7136-compatible prepregs in its own ecosystem.
• Lead-free assembly: T_d values of 390 °C and 380 °C, respectively, give comfortable margin above the ~260 °C peak reflow profile.

Fabricators experienced with RO4350B will find S7136 straightforward to process. The main watch-out is that some fabricators outside Asia may not stock S7136, leading to longer lead times. Conversely, factories in China often have S7136 on the shelf and may need to order RO4350B, reversing the lead-time equation. For a broader look at how Rogers and Shengyi product lines compare, see the full Rogers vs Shengyi overview.

Thermal and Mechanical Reliability

RO4350B’s lower z-axis CTE (32 ppm/°C vs ~40 ppm/°C for S7136 below T_g) translates to less barrel-crack risk during thermal cycling, particularly in boards thicker than 1.6 mm (63 mil) with small vias. For designs that undergo repeated power cycling or operate in harsh thermal environments (–40 °C to +85 °C automotive, for instance), the CTE advantage of RO4350B is meaningful.

Thermal conductivity is modestly better in RO4350B (0.69 vs ~0.60 W/m·K). In power-amplifier applications where the laminate must conduct heat away from an MMIC, this difference can shift junction temperature by a few degrees Celsius—worth modeling in your thermal simulation but rarely a deal-breaker on its own.

Cost and Supply Chain

S7136 is positioned as a cost-effective alternative to RO4350B. Exact pricing depends on thickness, panel size, order volume and regional availability, but as a qualitative guide:

• Raw laminate cost: S7136 is typically 30–50 % less expensive than RO4350B per unit area, depending on the supplier and volume tier.
• Availability in Asia: S7136 is widely stocked by Chinese fabricators, offering shorter lead times for prototypes and production runs manufactured in the region.
• Availability in North America and Europe: RO4350B has broader distribution and is stocked by most specialty RF fabricators. S7136 may need to be imported, adding lead time.
• Qualification overhead: Switching from RO4350B to S7136 on an existing qualified design requires re-validation of impedance, insertion loss and environmental testing, which carries engineering cost.

For new designs where the performance envelope fits, starting on S7136 avoids the qualification cost entirely and can meaningfully reduce BOM cost in volume. For a comparison of RO4350B against another popular alternative from a Western vendor, see I-Tera MT40 vs RO4350B.

Choosing the Right Shengyi Grade

Shengyi’s high-frequency portfolio extends beyond S7136 to include grades like S7439 (very low loss), S1600 (low-cost mid-performance) and others. If you are evaluating S7136 you should also check whether a different Shengyi grade better fits your loss and cost targets. The selector below lets you filter Shengyi’s laminate family by Dk, Df and application band.

Enter your target Dk range (e.g., 3.3–3.6) and maximum Df (e.g., 0.005 at 10 GHz). The tool returns matching Shengyi grades with key specs. If S7136 appears alongside S7439, compare their Df values: S7439 offers lower loss at a higher price point, potentially bridging the gap to RO4350B performance while staying in the Shengyi supply chain.

Frequency-Band Suitability

Sub-6 GHz (Wi-Fi, LTE, GNSS, ISM)

Both materials are excellent. The loss difference is imperceptible in most link budgets. S7136 is the pragmatic choice when cost matters and the supply chain is Asia-centric.

6–18 GHz (Ku-band satcom, radar altimeters, point-to-point)

RO4350B is the safer bet because its Dk stability with frequency is better characterized in this range. S7136 can work, but request frequency-dependent Dk/Df data from Shengyi and validate with test coupons. Designs operating in the sub-6 GHz to mmWave transition should pay close attention to how Dk shifts across the band.

24–28 GHz (5G mmWave, K-band radar)

RO4350B is commonly used at 24 GHz for ISM-band radar and at 28 GHz for 5G. S7136 has limited published data at these frequencies. Unless you can obtain and verify S7136 characterization data at your operating frequency, RO4350B (or a lower-loss grade) is the lower-risk path.

Above 30 GHz

Neither material is a first choice. Consider RO3003, Isola Astra MT77 or similar ultra-low-loss laminates. Our RF laminate comparison hub covers those options.

When to Choose RO4350B

• Operating frequency above 10 GHz where every 0.001 of Df matters.
• Tight impedance tolerance required and you need well-documented process Dk data.
• Harsh thermal cycling environment where lower z-axis CTE improves via reliability.
• Your fabricator is in North America or Europe and stocks Rogers but not Shengyi.
• Your customer or end application (aerospace, defense) specifies Rogers by name in the approved materials list.

When to Choose S7136

• Operating frequency at or below 10 GHz where the Df gap is negligible.
• Cost reduction is a primary driver and the 30–50 % laminate savings justifies the switch.
• Fabrication is in China or Southeast Asia where S7136 is locally stocked.
• You are designing a new product with no existing Rogers qualification to protect.
• Volume is high enough that even a modest per-panel saving compounds significantly.

Design Migration Checklist

If you are considering switching an existing RO4350B design to S7136, work through these steps:

1. Obtain S7136 Dk/Df data at your operating frequency—not just the 10 GHz headline number.
2. Re-run impedance calculations using S7136’s process Dk. Even if the nominal Dk matches, the tolerance distribution may differ.
3. Simulate insertion loss on your longest RF trace. Confirm the delta is within your link budget margin.
4. Check CTE compatibility in your stackup, especially for hybrid builds with FR-4 cores. Refer to IPC-6012 Class 3 requirements if your product demands high reliability.
5. Build test coupons—a 4-up panel with TRL calibration structures—and measure S-parameters through at least your highest frequency of interest.
6. Run thermal-cycling qualification per your product’s reliability spec (e.g., 500 cycles –40 °C to +125 °C) and inspect via cross-sections.
7. Document everything—material substitution without documented evidence is an audit risk in regulated industries.

RO4350B vs Other Alternatives

S7136 is not the only material compared with RO4350B. If your evaluation is broader, these comparisons may help:

• RO4350B vs RO4003C—same vendor, different Dk and flame-retardant chemistry.
• Rogers vs Isola overview—brand-level comparison across product families.

FAQ

Can S7136 directly replace RO4350B without redesign?

In many sub-10 GHz designs, yes, because the nominal Dk matches. However, you must verify impedance on test coupons and confirm that the slightly higher Df does not erode your link budget. A “drop-in” swap without measurement is not recommended.

Is S7136 approved for automotive or aerospace use?

Shengyi holds ISO 9001 and IATF 16949 certifications, and S7136 is used in automotive radar modules by several Tier-1 suppliers. Aerospace approval depends on the specific program’s qualified-products list; Rogers materials appear on more legacy QPLs.

What is the maximum usable frequency for S7136?

Shengyi’s published data covers performance up to about 10–15 GHz. Independent use at 24 GHz exists, but above that range the lack of published characterization data makes RO4350B or a dedicated mmWave laminate a safer choice.

Does S7136 work in hybrid stackups with FR-4?

Yes. S7136 bonds with standard low-flow prepregs and is routinely combined with Shengyi’s own S1000-2M or other FR-4 grades for mixed-signal boards. The CTE match between S7136 and FR-4 is comparable to that of RO4350B and FR-4.

How much cheaper is S7136 than RO4350B?

Raw laminate cost is typically 30–50 % lower, but total board cost also depends on fabrication yield, regional availability and any hybrid-stackup bonding materials. Request quotes for your specific stackup and volume to get an accurate comparison.