RO4835 + IT180 Hybrid High-Frequency PCB: A 6-Layer Board Solution Balancing 5G RF Performance and Cost

1. Panoramica del prodotto: A 6-Layer Hybrid PCB Balancing 5G RF Performance and Cost

Modern electronic devices often combine RF front-ends, high-speed digital signals, and power management on one board. Using expensive high-frequency materials for the entire board is neither economical nor necessary. This logic gave birth to theHigh Frequency Hybrid PCB.

UGPCB RO4835 + IT180 6-Layer High Frequency Hybrid PCB realizes this concept. It laminates Rogers RO4835 high-frequency laminate con ITEQ IT180 high-Tg FR-4 material in a single stackup. The final board has 1.5mm total thickness, 1OZ finished copper, E 50 ohm characteristic impedance.

RF signal layers use RO4835 to ensure signal integrity. Power and control layers use IT180 to cut material cost and provide mechanical support. This hybrid approach reduces material cost by30%–50% compared to a full Rogers solution. RF performance remains nearly unchanged. This makes it the top choice for cost-sensitive mass production projects like 5G base stations, 77 GHz automotive radar, and aerospace communications.

2. Definizione: What is “RO4835 + IT180 High Frequency Hybrid PCB”?

UNHigh Frequency Hybrid PCB bonds two or more different dielectric materials into one multilayer board. The core idea is simple – use expensive high-frequency material only on RF signal layers. Use lower cost standard FR-4 on other layers for mechanical strength and lower cost.

RO4835 is a hydrocarbon/ceramic-filled thermoset high-frequency laminate from Rogers’ RO4000® series. It offers very low dielectric loss (Df = 0.0037 @ 10 GHz) e costante dielettrica stabile (Dk = 3.48 ± 0.05). Unlike PTFE-based materials, RO4835 works with standard FR-4 processing. No special plasma etching or surface treatment is needed.

IT180 is a high-Tg lead-free epoxy FR-4 laminate from ITEQ. Its glass transition temperature (Tg) is 175°C (DSC method). Dk ≈ 4.1 and Df ≈ 0.016 A 10 GHz. IT180 offers excellent CAF resistance, low Z-axis CTE, and good through-hole reliability. It is widely used in automotive electronics, communication backplanes, and server motherboards.

Combining RO4835 and IT180 creates an electrically isolated and thermally compatible interface. RO4835 guarantees signal integrity. IT180 provides rigidity and cost advantages.

3. Classificazione scientifica (Per IPC and UL Standards)

According to IPC-4101 “Specification for Base Materials for Rigid and Multilayer Printed Boards”, this product belongs to theHybrid Multilayer PCB categoria.

• Per IPC-4103: RO4835 belongs to high frequency circuit laminates.
• Per IPC-4101C/126: IT180 belongs to high-Tg FR-4 laminates.
• Board Type: Rigid Multilayer PCB.
• Conta dei strati: 6 strati (ISU options available).
• Applicazione: RF/Microwave PCB for RF front-ends, Radar a onde millimetriche, and mixed-signal processing.
• Finitura superficiale: Essere d'accordo (electroless nickel immersion gold) for lead-free soldering and fine wire bonding.

4. Key Design Considerations for Hybrid Stackup

Designing a hybrid PCB ad alta frequenza requires more than simply stacking RO4835 and IT180. Four design rules determine success.

4.1 Impedance Control and Dielectric Constant Matching

This product targets50 ohm characteristic impedance – the standard for RF and microwave systems. To achieve accurate 50Ω control, you must account for the Dk of both RO4835 and IT180 layers.

• RO4835 (RF signal layers): Dk = 3.48 ± 0.05 @ 10 GHz (process value); Dk = 3.66 (design value). Utilizzo 3.66 for microstrip or coplanar waveguide geometry calculations to get the best impedance match.
• IT180 (inner/power layers): Dk = 4.4 @ 1 MHz; Dk = 4.1 @ 10 GHz. Avoid routing RF signals vertically across layers with different Dk values. Impedance steps cause signal reflections.

4.2 Managing CTE Mismatch

RO4835 in-plane CTE (X/Y axes) is 10–12 ppm/°C. Typical FR-4 CTE is about 17 ppm/° C.. The difference in thermal expansion can cause warpage, delaminazione, or even board bursting during lamination and reflow.

Common countermeasures include: keeping stackup symmetrical (same thickness and material type on top and bottom), using stepped lamination (gradual temperature and pressure rise), and adding anchoring copper in transition areas for mechanical constraint.

4.3 Layer Stackup and Signal Layer Assignment

For a 6-layer RO4835 + IT180 hybrid board, the recommended symmetrical stackup is:

Strato	Materiale	Funzione
Strato 1 (Superiore)	RO4835	RF microstrip / antenna signal
Strato 2	Strato interno	Reference ground plane
Strato 3	IT180 FR-4 core	Low-speed digital / energia
Strato 4	IT180 FR-4 core	Ground plane
Strato 5	Strato interno	Reference ground plane
Strato 6 (Bottom)	RO4835	RF microstrip / feed network

This symmetrical design minimizes asymmetric warpage from thermal stress. Both top and bottom layers use RO4835 – a sandwich structure. The inner IT180 core provides rigidity and cost savings.

4.4 Isolating RF from Digital Signals

The Dk difference between RO4835 (~3.48) and IT180 (~4.1) is about 0.6. If a high-frequency signal crosses the hybrid interface, reflections and mode conversion will increase insertion loss significantly. Perciò, route all high-speed/RF traces only on RO4835 layers. Never route RF across the hybrid boundary into the IT180 region.

5. Principio di lavoro: Why RO4835 Excels at High Frequencies?

The core challenge of high-frequency circuits is simple: higher signal frequency means greater parasitic loss in the PCB substrato. Two key parameters determine this loss – dielectric constant (Non so) and dissipation factor (Df).

5.1 Costante dielettrica (Non so)

Dk measures how much electrical energy the material can store. The smaller the Dk change across frequency, the better the impedance consistency over a wide bandwidth. RO4835’s Dk is3.48 ± 0.05 A 10 GHz (process value). Its thermal stability is only 50 ppm/°C from -50°C to 150°C. That means Dk barely drifts with temperature.

5.2 Fattore di dissipazione (Df)

Df (loss tangent) directly measures signal energy lost as heat in the dielectric. Lower Df means less lost energy. RO4835’s Df is only0.0037 A 10 GHz. For comparison, standard FR-4 has Df around 0.02 A 1 GHz. RO4835’s loss is about1/5 that of FR-4.

RO4835 achieves this low loss through its unique hydrocarbon/ceramic filler system. Hydrocarbon provides a low-polarity molecular backbone. Ceramic filler stabilizes mechanical dimensions and improves thermal conductivity. After high-temperature curing, the material forms a cross-linked thermoset network – which is exactly why RO4835 works with standard FR-4 PCB processes.

6. Applicazioni: Five Core Use Cases for RO4835 + IT180 Hybrid PCBs

The value of this hybrid PCB is not just in its electrical performance – but in its reliable operation under real-world conditions. Below are five major application areas.

6.1 5G Infrastruttura di comunicazione

5G millimeter-wave bands (per esempio., n257/n258/n261, 24.25–29.5 GHz) demand very low PCB loss. According to a report by 360iResearch, the global 5G PCB market reached $22.3 miliardi di 2025 and is projected to grow to $59.44 miliardi di 2032 in un CAGR di 15.03%.

RO4835 + IT180 hybrid PCBs are used in 5G small cells, massive MIMO antenna arrays, and RF front-end modules. They control material cost in mass production while meeting strict insertion loss requirements.

6.2 77 GHz Automotive Radar (Adas)

Modern ADAS systems use 77 Radar a onde millimetriche GHz. This is one of the most representative applications for high frequency hybrid PCBs. RO4835’s Dk at 77 GHz is about 3.2 (down from 3.48 A 10 GHz). Combined with LoPRO® reverse treated copper foil, insertion loss is minimized.

IT180’s Tg of 175°C and T260 > 60 minutes provide high thermal reliability. This allows the radar module to survive harsh thermal cycling from -40°C to +125°C near the engine compartment.

6.3 Aerospace and Satellite Communications

Aerospace applications require Materiali PCB to remain reliable under vacuum, high radiation, and extreme temperatures. RO4835 offers 10 times better oxidation resistance than conventional thermoset materials. It also passes non-voiding delamination tests, making it a trusted choice for LEO satellite communication payloads and phased array antennas.

6.4 RF Power Amplifiers

In base station power amplifier (PA) moduli, RO4835’s low loss directly translates to higher output power and lower heat generation. Its thermal conductivity of 0.69 W/m · k (measured) quickly conducts heat away from PA chips to heat sinks, extending device lifetime.

6.5 High-Speed Mixed-Signal Boards

When a board contains high-speed ADCs/DACs, FPGA, and RF front-end channels, crosstalk becomes a serious issue. The RO4835 + IT180 hybrid creates a natural dielectric constant barrier between RF and digital layers. This effectively suppresses digital noise coupling into RF paths.

7. Materiali: Detailed Technical Specifications of RO4835 and IT180

The table below lists official key parameters for RO4835 and IT180 with test method references.

Parametro	RO4835 (Rogers)	IT180 (ITEQ)	Test Standard / Fonte
Non so @ 10 GHz	3.48 ± 0.05 (processo)	4.1	IPC-TM-650 2.5.5.5 / 2.5.5.13
Non so @ 1 MHz	-	4.4	IPC-TM-650 2.5.5.9
Df @ 10 GHz	0.0037	0.016	IPC-TM-650 2.5.5.5 / 2.5.5.13
Tg (DSC)	≥280° C.	175° C.	IPC-TM-650 2.4.24.3
Td (5% perdita di peso)	390° C.	345° C.	ASTM D3850 / TGA
Conducibilità termica	0.66–0.69 W/m·K	-	ASTM C518 / ASTM D5470
Flammability rating	UL 94 V-0	UL 94 V-0	UL 94
Resistività al volume	5 × 10⁸ MΩ·cm	Per IPC-4101	IPC-TM-650 2.5.17.1
Cte (X/Y axis)	10 / 12 ppm/° C.	11–13 / 13–15 ppm/°C	IPC-TM-650 2.1.24 / TMA
Cte (Z axis, A1)	31 ppm/° C.	45 ppm/° C.	IPC-TM-650 2.1.24 / TMA
Moisture absorption	0.05%	-	ASTM D570

Data accuracy note: All values above have been verified against official Rogers Corporation and ITEQ data sheets. The volume resistivity value 5×10⁸ MΩ·cm is from Rogers official documentation. Some earlier documents use 1.2×10¹⁰ Ω·cm which may result from unit conversion but does not change the conclusion that the material has excellent insulating properties.

8. Performance Features

Based on the technical parameters above, this high frequency hybrid PCB offers five core advantages:

1. Very low signal loss: Df = 0.0037 @ 10 GHz – about 1/5 of ordinary FR-4. In 5G mmWave bands, this means longer transmission distance, lower errors, and less heating.
2. Stable dielectric constant: Dk = 3.48 ± 0.05 @ 10 GHz. Very stable over wide frequency and temperature ranges. Ensures accurate 50Ω impedance under all operating conditions.
3. Excellent heat and oxidation resistance: RO4835 has 10 times better oxidation resistance than traditional thermoset materials. It works long-term in high-temperature air without significant degradation.
4. Superior manufacturability: No special surface treatment (like plasma etching) needed. Fully compatible with standard FR-4 processes. This shortens lead times significantly.
5. Cost-effective design: Only RF critical layers use RO4835. Inner layers use IT180. Material cost is about 30%–50% lower than a full Rogers solution under the same electrical constraints.

9. Processo di produzione: 8 Key Steps from Material to Finished Board

A qualified RO4835 + IT180 high frequency hybrid PCB goes through the following eight critical processes:

① Incoming material inspection – Sample test Dk/Df consistency of RO4835 and IT180 batches. Ensure parameters meet Rogers and ITEQ official specifications.

② Inner layer circuit formation – Pattern transfer and etching on IT180 layers for digital signal lines and power/ground planes.

③ Brown oxide treatment – Chemically roughen inner layer copper surfaces. Improve adhesion with prepreg during lamination.

④ Lamination – The most critical step. Stack RO4835, pre -preg, and IT180 cores in a symmetrical stackup. Load into a vacuum press. Precisely control temperature ramp rate, pressure curve, and dwell time to minimize stress from CTE mismatch. For this 6-layer product, single high-temperature lamination is typical. HDI designs use sequential lamination.

⑤ Drilling – Use solid carbide drills or laser drilling. Optimize parameters for 1.5mm board thickness to ensure hole wall roughness meets PTH copper plating requirements.

⑥ Electroless copper / panel plating – Metallize through-holes. Establish electrical interconnection between layers.

⑦ Outer layer circuit formation – Fabricate 50Ω impedance microstrip lines or RF traces on top and bottom RO4835 layers. Use controlled impedance etching to keep trace width tolerance within ±5%.

⑧ Surface finish – ENIG (electroless nickel immersion gold) for lead-free soldering and fine wire bonding. Typical gold thickness 0.05–0.1 μm. Nickel thickness 3–5 μm.

⑨ Electrical test and flying probe - 100% electrical test including open/short and TDR impedance test. Ensure each board meets 50Ω impedance tolerance.

10. Physical Structure of the 6-Layer Hybrid Board

Below is the physical construction of UGPCB’s RO4835 + IT180 6-layer board (dall'alto verso il basso):

Articolo	Componente	Materiale	Typical Thickness	Funzione
1	Top copper foil	ED copper (LoPRO® optional)	1 OZ (≈35 μm)	Outer layer signal / antenna
2	Top dielectric	RO4835	0.127 mm	High frequency signal insulation
3	Inner copper (L2/L5)	Rame	1 OZ	Reference ground plane
4	Mid core	IT180 FR-4	Per stackup design	Digital signal / power layer
5	Mid core	IT180 FR-4	Per stackup design	Ground plane
6	Inner copper (L3/L4)	Rame	1 OZ	Inner routing / energia
7	Bottom dielectric	RO4835	0.127 mm	High frequency signal insulation
8	Bottom copper foil	ED copper (LoPRO® optional)	1 OZ (≈35 μm)	Bottom signal / feed network
9	Finitura superficiale	Essere d'accordo	0.05–0.1 μm (Au)	Solderability and oxidation resistance

Total board thickness is 1.5 mm including all copper and dielectric layers.

11. Product Selection Quick Reference

Parametro	Specifica	Customizable Range
Laminate combination	Rogers RO4835 + ITEQ IT180	RO4350B + FR-4 or other ITEQ series
Layer count	6 strati	Expandable to 4/6/8/10 layers plus HDI
Spessore della scheda	1.5 mm	0.8–3.0 mm (based on layer count and stackup)
Spessore del rame	Finito 1 OZ	0.5 OZ / 1 OZ / 2 OZ
Controllo dell'impedenza	50 ohm (single-ended)	Differential 90Ω/100Ω and others
Spessore dielettrico	0.127 mm	Based on stackup requirements
Non so (RO4835 @10 GHz)	3.48 ± 0.05	Material-dependent
Df (RO4835 @10 GHz)	0.0037	Material-dependent
Flammability rating	UL 94 V-0	Required
Finitura superficiale	Essere d'accordo	OSP, immersion tin, immersion silver

12. Why Choose UGPCB for Your Hybrid PCB Needs?

UGPCB has deep engineering experience in high frequency hybrid PCBs. We help customers avoid common risks like material incompatibility, layer delamination, and reliability test failures. Our core strengths include:

• ✅ Solid high-frequency design support – From impedance calculation (using Rogers MWI and Polar SI9000) to CTE stress simulation of stackups.
• ✅ Precise process control – X-ray real-time alignment and AOI ensure layer-to-layer registration within ±3 mil.
• ✅ Batch consistency – Even in mass production, RO4835 Dk batch variation stays within ±0.05. 50Ω impedance yield exceeds 98%.
• ✅ Fast response and on-time delivery – Strategic inventory of Rogers and ITEQ raw materials. Lead time for hybrid quick-turn PCBs is as short as 7–10 working days.

Request a Quote Now

The RO4835 + IT180 high frequency hybrid PCB is the best solution for balancing performance and cost. Whether you are designing a 5G small cell or qualifying a 77 GHz radar module for mass production, UGPCB provides one-stop service from engineering validation to volume manufacturing.

📧Contact UGPCB Engineering Team: sales@ugpcb.com
📞Technical Hotline: +86-XXX-XXXXXXX
🌐Visit our website: www.ugpcb.com

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Please provide the following information:

• PCB layer count and target board thickness
• Number of RF layers and frequency range
• Estimated annual volume (prototype / small batch / produzione di massa)
• Impedance control requirements (single-ended/differential, target value and tolerance)
• Any special process requirements (back drilling, buried/blind vias, controlled depth drilling, ecc.)

UGPCB’s engineering team will respond within 24 hours with technical support and a detailed quote.

*All technical data in this document come from Rogers Corporation official data sheet (DS RO4835) and ITEQ IT-180A technical specification. Test methods follow IPC-TM-650 series and applicable ASTM standards. Market data source: 360iResearch “5G Printed Circuit Board Market” rapporto (January 2026). UGPCB is responsible for the accuracy and timeliness of the data. For any technical questions, please contact our engineering team for confirmation.*