RO4003C + 370HR 10-Layer Hybrid PCB – Impedance Controlled & High Reliability Applications

1. Introduction to RO4003C + 370HR Hybrid PCB

RO4000® series hydrocarbon ceramic laminates are designed to offer superior high frequency performance and low cost circuit fabrication. The result is a low loss material which can be fabricated using standard epoxy/glass (FR-4) processes at competitive prices.

370HR is a high performance 180°C glass transition temperature (Tg) FR-4 system for multilayer Printed Wiring Board (PWB) applications where maximum thermal performance and reliability are required. This system provides improved thermal performance and low expansion rates in comparison to traditional FR-4 while retaining FR-4 processability.

This 10-layer hybrid PCB combines RO4003C for outer layers (high frequency signal integrity) and 370HR for inner layers (thermal reliability), offering exceptional electrical performance, impedance control, and mechanical stability for demanding RF, microwave, and high-speed digital applications.

2. Key Features of RO4003C

• Dielectric constant of 3.38 ± 0.05 at 10 GHz (process) / 3.55 (design)

• Dissipation factor of 0.0027 at 10 GHz

• Thermal coefficient of dielectric constant (TCDk) of +40 ppm/°C

• Tg >280°C (TMA)

• Td of 425°C

• Low moisture absorption of 0.06%

• CTE (X/Y/Z): 11/14/46 ppm/°C

• Thermal conductivity of 0.71 W/(m·K)

• Compatible with standard FR-4 processing

• No specialized via preparation required

3. Key Features of 370HR

• Tg of 180°C by DSC

• Td of 340°C (5% weight loss)

• T260 >60 min, T288 >30 min, T300 >2 min

• CTE (Z-axis pre-Tg): 45 ppm/°C, (post-Tg): 230 ppm/°C

• Z-axis expansion (50-260°C): 2.8%

• Dk of 4.04 @ 10 GHz, Df of 0.0250 @ 10 GHz

• Thermal conductivity of 0.4 W/(m·K)

• UL 94V-0 flammability rating

• Max operating temperature: 130°C

4. Benefits of RO4003C + 370HR Hybrid PCB

• Combines high frequency performance (RO4003C) with thermal reliability (370HR)

• Standard FR-4 processing for both materials – no PTFE special handling

• Excellent dimensional stability for mixed dielectric multilayer constructions

• Low Z-axis CTE ensures reliable plated through-hole quality

• Impedance control ready for RF and high-speed digital designs

• Halogen-free option (370HR) for environmentally conscious designs

• Laser fluorescing and UV blocking for AOI compatibility

5. PCB Construction Details

6. PCB Stackup (10-Layer Hybrid Rigid Structure)

• L1 (Top Copper): 1 oz (0.035 mm) – 50Ω impedance trace: 12.2 mil width

• Core: RO4003C – 0.203 mm (8 mil)

• L2 (Inner Copper): 1 oz (0.035 mm)

• Prepreg: RO4450F ×2 – 0.204 mm

• L3 (Inner Copper): 0.5 oz (0.017 mm) – 80Ω diff pair: 3.5 mil trace / 5.5 mil spacing

• Core: 370HR FR-4 – 0.102 mm

• L4 (Inner Copper): 0.5 oz (0.017 mm)

• Prepreg: 370HR – 0.102 mm

• L5 (Inner Copper): 1 oz (0.035 mm)

• Core: 370HR FR-4 – 0.102 mm

• L6 (Inner Copper): 1 oz (0.035 mm)

• Prepreg: 370HR – 0.102 mm

• L7 (Inner Copper): 0.5 oz (0.017 mm)

• Core: 370HR FR-4 – 0.200 mm

• L8 (Inner Copper): 0.5 oz (0.017 mm)

• Prepreg: RO4450F ×2 – 0.204 mm

• L9 (Inner Copper): 1 oz (0.035 mm)

• Core: RO4003C – 0.203 mm (8 mil)

• L10 (Bottom Copper): 1 oz (0.035 mm)

Total Pressed Thickness: 1.618 mm (1.7 mm nominal)

7. Impedance Control Specifications

8. PCB Special Features

• Blind Vias: L1-L2, L9-L10, L7-L10

• Through Holes: Full stack

• Resin Plugging: All vias resin filled and capped

• Asymmetric Copper: L5/L6 1 oz, L3/L4/L7/L8 0.5 oz

• Impedance Control: 50Ω and 80Ω controlled lines

9. Primary Application Areas

• RF and microwave circuits

• High-speed digital designs

• Base station and telecom equipment

• Automotive radar and sensors

• Satellite communication systems

• Point-to-point digital radio

• High reliability industrial controls

• Backplanes and multilayer motherboards

10. Quality Assurance

• Artwork supplied: Gerber RS-274-X

• Accepted standard: IPC-Class-2 (typical)

• Availability: Worldwide

• RO4003C compliant with IPC-4103/10

• 370HR compliant with IPC-4101E Type /127, /128, /130

11. RO4003C High Frequency Laminate Introduction

RO4000 hydrocarbon ceramic laminates are designed to offer superior high frequency performance and low cost circuit fabrication. The result is a low loss material which can be fabricated using standard epoxy/glass (FR-4) processes at competitive prices.

RO4003C material possesses the properties needed by designers of RF microwave circuits, matching networks, and controlled impedance transmission lines. Low dielectric loss allows RO4003C to be used in many applications where higher operating frequencies limit the use of conventional circuit board laminates. The temperature coefficient of dielectric constant is among the lowest of any circuit board material, and the dielectric constant is stable over a broad frequency range.

RO4003C's thermal coefficient of expansion (CTE) is similar to that of copper, providing excellent dimensional stability and reliable plated through-hole quality, even in severe thermal shock applications. RO4003C has a Tg of >280°C, so its expansion characteristics remain stable over the entire range of circuit processing temperatures.

RO4003C laminates can easily be fabricated into printed circuit boards using standard FR-4 circuit board processing techniques. Unlike PTFE based high performance materials, RO4003C does not require specialized via preparation processes such as sodium etch.

12. 370HR High Performance Laminate Introduction

370HR is a high performance 180°C glass transition temperature (Tg) FR-4 system for multilayer Printed Wiring Board (PWB) applications where maximum thermal performance and reliability are required. 370HR laminate and prepreg products are manufactured with a unique high performance multifunctional epoxy resin, reinforced with electrical grade (E-glass) glass fabric.

This system provides improved thermal performance and low expansion rates in comparison to traditional FR-4 while retaining FR-4 processability. In addition to this superior thermal performance, the mechanical, chemical and moisture resistance properties all equal or exceed the performance of traditional FR-4 materials.

The 370HR system is also laser fluorescing and UV blocking for maximum compatibility with Automated Optical Inspection (AOI) systems, optical positioning systems and photoimagable solder mask imaging. 370HR has proven to be best in class for sequential lamination designs.

13. RO4003C Data Sheet

14. 370HR Data Sheet

15. Typical Applications

• RF and microwave circuits

• High-speed digital designs

• Base station and telecom equipment

• Automotive radar and sensors

• Satellite communication systems

• Point-to-point digital radio

• High reliability industrial controls

• Backplanes and multilayer motherboards

• Sequential lamination designs

• Power amplifiers and filters

16. Standard Thicknesses, Panel Sizes & Claddings

• 24" × 18" (610 mm × 457 mm)

• 24" × 21" (610 mm × 533 mm)

• 24" × 36" (610 mm × 915 mm)

• 48" × 36" (1219 mm × 915 mm)

• Electrodeposited Copper Foil: ½ oz (18 μm) HH/HH, 1 oz (35 μm) H1/H1