8-Layer Hybrid PCB RO4003C + S1000-2M FR4 with ENIG Surface Finish Blind Via

8-Layer Hybrid PCB RO4003C + S1000-2M FR4 with ENIG Surface Finish Blind Via

Product Brief Introduction

This custom 8-layer hybrid laminate PCB integrates Rogers RO4003C high-frequency hydrocarbon ceramic substrates and Shengyi S1000-2M high-Tg low Z-CTE FR4 prepreg, targeting RF microwave, automotive radar, and base station communication hardware that simultaneously demands ultra-low high-frequency signal loss and reliable multi-layer mechanical structure.

Traditional full Rogers multi-layer PCBs suffer from high raw material cost and complicated lamination yield control; pure FR4 boards cannot meet low insertion loss requirements above 500MHz. This hybrid stacking architecture balances high-frequency electrical performance, manufacturing cost and thermal-mechanical reliability, forming a differentiated competitive advantage compared with single-material PCB solutions. The mixed copper inner layer design optimizes power plane current carrying capacity and high-speed signal routing density, while blind vias and resin plug technology eliminate cavity risks during reflow soldering and enhance high-density layout feasibility.

1. PCB Construction Details

The following table summarizes the complete construction parameters, highlighting the strategic material placement and layer sequencing that enables optimal signal integrity and thermal management.

2. PCB Stackup Configuration

The layer stackup is engineered with symmetrical construction to minimize warpage during thermal cycling, with high-frequency RO4003C cores placed on outer positions to optimize signal launch and termination performance.

3. Core Differentiated Technical Advantages of This Hybrid PCB

3.1 Dual High-Frequency Outer Layer Design: 

• 0.203mm standard RO4003C thickness strictly follows Rogers official material specification, delivering Dk=3.38±0.05 and Df=0.0027 @10GHz, effectively restraining high-frequency insertion loss for antenna and matching circuit traces. Unlike full FR4 boards with Df above 0.018 at 1GHz, this hybrid stack maintains consistent electrical performance up to 40GHz operating frequency.

3.2 S1000-2M Middle Dielectric Stabilizes Multi-Layer Reliability:

• S1000-2M features ultra-low Z-axis CTE (41ppm/℃before Tg) and Tg=185℃DMA, eliminating layer delamination or barrel crack risks during multiple lead-free reflow cycles (peak 260℃). Its excellent anti-CAF performance avoids conductive filament growth under high temperature & humidity long-term operation, critical for outdoor communication equipment.

3.3 Optimized Interconnection Process Matching:

• Dual-side blind vias reduce routing detour length and improve signal transmission linearity; full resin plug vias eliminate solder overflow and air expansion issues during assembly, compatible with dense BGA component layout. Yin-yang mixed inner copper balances heavy current power plane conduction and fine-line signal layer miniaturization, avoiding single copper thickness waste of board space.

4. Application Scenarios

This 8-layer hybrid PCB is specifically tailored for applications requiring a combination of high-frequency signal processing and robust power delivery within a single integrated substrate. Typical applications include:

• 5G Wireless Infrastructure
• Aerospace and Defense Systems
• High-Speed Digital Processing
• Automotive Radar and ADAS

5. PCB Section Conclusion

This 8-layer RO4003C & S1000-2M hybrid PCB achieves a balanced solution between high-frequency electrical performance, multi-layer structural reliability and manufacturing cost, solving the core pain points of single-material PCBs in RF communication hardware. The standardized stackup, controlled blind/resin plug via process and unified surface treatment parameters ensure stable batch production consistency. It is universally applicable to cellular base station power amplifiers, automotive millimeter-wave radar, satellite LNB modules and broadband RF identification equipment, with scalable customization on panel size, copper weight and hole dimension based on client design requirements.

CCL Material Knowledge: RO4003C and S1000-2M

1. Rogers RO4003C High-Frequency Laminate

1.1 Material Overview

Rogers 4003C is a hydrocarbon ceramic laminate developed by Rogers Corporation specifically for high-frequency circuit applications. Unlike PTFE-based materials that require specialized processing, RO4003C is a rigid thermoset material that can be fabricated using standard FR-4 processing techniques. This characteristic significantly reduces manufacturing complexity and cost while delivering superior high-frequency performance. The hydrocarbon ceramic filler system provides a unique combination of low dielectric loss, stable dielectric constant over temperature and frequency, and excellent dimensional stability.

1.2 Rogers RO4003C High-Frequency CCL Full Datasheet Parameter Table

1.3 Key Advantages and Differentiators

1) Superior High-Frequency Performance:

• The combination of low dielectric constant and ultra-low dissipation factor makes RO4003C suitable for applications up to 40 GHz and beyond. The stable dielectric constant over temperature—among the lowest of any circuit board material—ensures consistent RF performance across operating temperature ranges, critical for aerospace, defense, and automotive radar applications.

2) FR-4 Process Compatibility:

• Unlike PTFE-based high-frequency materials that require sodium etch for via preparation and special handling, RO4003C can be processed using standard FR-4 production equipment and procedures. This reduces manufacturing cycle time, lowers production costs, and enables hybrid constructions with conventional FR4 materials without additional processing complexity.

3) Excellent Dimensional Stability:

• The CTE matching with copper (11 ppm/°C in X-direction and 14 ppm/°C in Y-direction versus copper's 17 ppm/°C) ensures reliable plated through-hole quality and dimensional stability during thermal cycling. The Z-axis CTE of 46 ppm/°C is significantly lower than standard FR4 materials (typically 100-200 ppm/°C), reducing via cracking risk during thermal shock.

4) High Thermal Reliability:

• With Tg exceeding 280°C and Td of 425°C, RO4003C withstands multiple lead-free soldering cycles without degradation of dielectric properties. The material maintains its expansion characteristics over the entire circuit processing temperature range, ensuring consistent performance through assembly processes.

5) LoPro® Foil Option:

• The availability of LoPro reverse-treated copper foil reduces insertion loss by up to 15% compared to standard electrodeposited copper, as shown in Chart 3 of the data sheet. This option is particularly valuable for millimeter-wave applications where conductor loss dominates total loss budget.

1.4 Design Considerations

• The design Dk of RO4003C decreases by approximately 0.1 as core thickness decreases from 0.020" to 0.004". Designers should consider the LoPro resin Dk of approximately 2.4 when using reverse-treated foil; however, the average design Dk noted in the data sheet table should be used for design calculations. The prolonged exposure in oxidative environments may cause changes to dielectric properties, particularly at elevated temperatures. While oxidation-related performance issues are extremely rare, Rogers recommends evaluating each material and design combination for fitness over the entire product lifecycle.

1.5 Available Configurations

RO4003C is offered in standard thicknesses including：

• 0.008" (0.203mm), 0.012" (0.305mm), 0.016" (0.406mm), 0.020" (0.508mm), 0.032" (0.813mm), and 0.060" (1.524mm) with tolerances ranging from±0.0010" to±0.0040".

• Additional non-standard thicknesses are available from 0.0066" to 0.060" in varying increments.

• Standard panel sizes include 24"×18", 24"×21", 24"×36", and 48"×36".

• Standard claddings include½oz. and 1 oz. electrodeposited copper foil, with additional cladding weights available upon request.

2. Shengyi S1000-2M High-Performance FR4 Laminate

2.1 Material Overview

S1000-2M is a high-performance FR4 laminate manufactured by Shengyi Technology, designed for applications requiring superior thermal reliability and high layer count capability. The material features a high Tg of 185°C (DMA method), exceptional CAF (Conductive Anodic Filament) resistance, and demonstrated reliability through IST testing. S1000-2M is ideal for use in hybrid constructions with high-frequency materials, providing cost-effective support for power distribution, grounding, and lower-speed digital routing.

2.2 Shengyi S1000-2M High-Tg Low CTE FR4 Prepreg Datasheet Parameter Table

2.3 Reliability Validation

1) High Layer Count Performance:

• S1000-2M has been validated in 24-layer constructions with 0.13mm cores and 1080/2116 prepreg combinations, achieving overall thickness of 4.0mm with minimum hole size of 0.35mm and aspect ratio of 11.5:1. These constructions successfully withstand five cycles of 260°C lead-free reflow without delamination or reliability issues.

2) IST Testing:

• Interconnect Stress Testing on 20-layer constructions with 1080+2116 prepreg, preconditioned with six reflow cycles (peak 260°C), demonstrates power cycles exceeding 2,000 under room temperature to 150°C cycling conditions. This validates the material's robust via reliability and resistance to thermomechanical fatigue.

3) CAF Resistance:

• Anti-CAF testing on 20-layer boards with through-hole to through-hole spacing of 16 mil and 20 mil, preconditioned with six lead-free reflow cycles (peak 260°C), shows successful resistance for over 1,000 hours at 65°C/87% RH/100V DC. This excellent CAF resistance is critical for high-density designs with closely spaced vias operating in humid environments.

2.4 Prepreg Parameters

S1000-2M prepregs are offered in multiple glass fabric styles with controlled resin content and flow characteristics optimized for high layer count processing:

2.5 Processing Recommendations

• Hot Pressing Cycle: The recommended heat-up rate is 1.5-2.5°C/min from 80-140°C, with a minimum curing time of 90 minutes at 180-190°C. These parameters ensure proper resin flow and cross-linking for consistent laminate quality.

• Storage Conditions: For short-term storage (within three months), maintain temperature below 23°C and relative humidity below 50% RH. For long-term storage (up to six months), store at 5°C and normalize in room temperature for at least 4 hours before use. Prepregs should be kept wrapped in damp-proof material to prevent moisture absorption that weakens bonding strength. Avoid exposure to ultraviolet rays and strong lights.

2.6 Hybrid Construction Synergies

The combination of RO4003C and S1000-2M in this 8-layer design leverages complementary properties:

• Signal Integrity and Thermal Performance: RO4003C provides exceptional high-frequency performance on outer signal layers where insertion loss and signal integrity are paramount, while S1000-2M provides robust thermal and mechanical support for inner power distribution layers at a lower cost point. This hybrid approach delivers performance equivalent to all-high-frequency constructions at approximately 40-50% lower material cost.

• Manufacturing Compatibility: Both materials are compatible with standard FR-4 processing equipment and parameters, enabling seamless lamination, drilling, and plating operations. The RO4003C's thermoset nature and CTE matching with copper allow reliable via formation and plating integrity across the hybrid interface.

• Thermal Reliability: The combination of high Tg materials (RO4003C >280°C, S1000-2M 185°C) ensures the board withstands the thermal demands of lead-free assembly processes and harsh operating environments. The matched CTE characteristics reduce thermomechanical stress across the hybrid interface, improving long-term reliability.

• Cost Optimization: By using S1000-2M in inner layers where high-frequency performance is less critical, the overall material cost is significantly reduced compared to a full RO4000 series construction, while maintaining superior performance at the critical signal launch and termination interfaces.

CCL & Prepreg Material Chapter Conclusion

The matching combination of Rogers RO4003C high-frequency laminate and Shengyi S1000-2M low Z-CTE FR4 prepreg forms the core technical foundation of this 8-layer hybrid PCB. RO4003C supplies low-loss broadband high-frequency transmission capability for outer RF traces, while S1000-2M provides robust multi-layer thermal-mechanical bonding, humidity resistance and cost optimization.

All parameters cited in this chapter are fully extracted from official manufacturer datasheets with standardized IPC/ASTM test methods, providing accurate material performance reference for circuit design, impedance simulation, manufacturing process development and long-term product reliability assessment. The complementary material characteristics eliminate the respective limitations of single high-frequency substrate and ordinary FR4, which is the core differentiated advantage of hybrid RF PCBs compared with full Rogers or full FR4 alternatives.