In modern electronic product development, PCB stackup design has become one of the most important factors affecting electrical performance, signal integrity, thermal reliability, and manufacturing cost.
While traditional FR4 PCB stackup remains the most widely used solution for consumer electronics, industrial equipment, and general control systems, advanced applications such as 5G communication, RF circuits, radar systems, aerospace electronics, and high-speed computing increasingly require High Frequency PCB stackup materials.
This article explains the key differences between FR4 PCB stackup and High Frequency PCB stackup, helping engineers select the right solution for their applications.
1. What Is a PCB Stackup?
A PCB stackup refers to the arrangement of copper layers, dielectric materials, prepreg, and core materials inside a multilayer printed circuit board.
A typical multilayer PCB stackup includes:
- Top copper layer
- Prepreg dielectric layer
- Inner signal layers
- Ground planes
- Power planes
- Core material
- Bottom copper layer
The PCB stackup design determines:
- Controlled impedance performance
- Electromagnetic interference (EMI)
- Thermal management
- Mechanical strength
- Manufacturing complexity
For example, a typical 6-layer PCB stackup may include:
- Layer 1: Signal
- Layer 2: Ground Plane
- Layer 3: Signal
- Layer 4: Power Plane
- Layer 5: Ground Plane
- Layer 6: Signal
However, the dielectric material used between these layers determines whether the PCB is suitable for low-frequency applications or high-frequency applications.
2. FR4 PCB Stackup Explained
What Is FR4 Material?
FR4 is the most common PCB substrate material worldwide.
FR4 stands for: Flame Retardant 4
It is a fiberglass-reinforced epoxy laminate with excellent:
- Mechanical strength
- Electrical insulation
- Thermal stability
- Cost efficiency
Common FR4 PCB materials include:
- Standard FR4
- High TG FR4
- Low-loss FR4
- Halogen-free FR4
Popular FR4 material suppliers include:
- Shengyi Technology (S1141, S1000 series)
- Panasonic (R-1755)
- Isola (370HR)
- Kingboard PCB materials
Typical FR4 PCB Stackup Structure
A standard 4-layer FR4 PCB stackup:
Layer 1: Copper Signal
Prepreg
Layer 2: Ground Plane
FR4 Core
Layer 3: Power Plane
Prepreg
Layer 4: Copper Signal
Advantages:
- Low manufacturing cost
- Easy processing
- High availability
- Suitable for most electronic products
Limitations:
- Higher dielectric loss at high frequencies
- Less stable dielectric constant
- Limited RF performance
3. High Frequency PCB Stackup Explained
High Frequency PCB stackup is designed for applications where signal frequency typically exceeds several hundred MHz or GHz ranges.
These PCBs require specialized materials with:
- Low dielectric loss
- Stable Dk value
- Low dissipation factor
- Controlled impedance capability
Common high-frequency PCB materials include:
Rogers PCB Materials
Examples:
- Rogers RO4003C
- Rogers RO4350B
- Rogers RT5880
Panasonic High-Speed Materials
Examples:
- Megtron 6
- Megtron 7
Taconic Materials
Examples:
- TLY Series
- RF-35
High Frequency PCB stackups are commonly used in:
- RF communication systems
- Microwave circuits
- Satellite electronics
- Automotive radar
- 5G base stations
4. FR4 vs High Frequency PCB Stackup: Key Differences
Material Composition Difference
The biggest difference between FR4 and High Frequency PCB stackup is the dielectric material.
FR4 uses:
- Glass fiber
- Epoxy resin
High Frequency materials use:
- PTFE (Teflon)
- Ceramic-filled resin
- Hydrocarbon resin
- Advanced low-loss materials
These materials provide better electrical performance at high frequencies.
5. Dielectric Constant (Dk) Comparison
Dielectric constant directly affects signal propagation speed and impedance.
Typical values:
FR4
Dk: 4.0 – 4.8
Rogers RO4350B
Dk: 3.48
Rogers RT5880
Dk: 2.20
Lower and more stable Dk improves:
- Signal timing accuracy
- RF performance
- High-speed transmission
For high-speed applications such as PCIe, DDR5, and RF communication, stable Dk control is critical.
6. Signal Loss Comparison
Signal loss increases as frequency increases.
FR4:
- Suitable below several GHz
- Higher insertion loss
- More signal attenuation
High Frequency PCB:
- Lower dielectric loss
- Better transmission efficiency
- Suitable for microwave applications
For example: A 10 GHz RF signal transmitted through standard FR4 may experience significantly higher attenuation compared with Rogers materials.
7. Impedance Control Differences
Controlled impedance is essential for:
- RF circuits
- High-speed digital designs
- Antenna systems
- Communication equipment
FR4 PCB:
Typical impedance tolerance: ±10%
High Frequency PCB:
Typical impedance tolerance: ±5% or better
High-frequency PCB stackups require precise control of:
- Copper thickness
- Dielectric thickness
- Trace width
- Material Dk value
Professional PCB manufacturers use simulation software such as:
- Polar Si9000
- Ansys HFSS
- Cadence Allegro
for stackup optimization.
8. Cost Comparison: FR4 vs High Frequency PCB Stackup
Material selection significantly affects PCB manufacturing cost.
FR4 PCB Stackup Cost
- Typical 4-layer FR4 PCB prototype: $50 – $200
- Small batch production: $5 – $30 per PCB
High Frequency PCB Stackup Cost
- Typical Rogers PCB prototype: $150 – $800
- Complex RF multilayer PCB: $500 – $3000+
Factors affecting cost:
- Material brand
- Layer count
- Copper thickness
- Surface finish
- Controlled impedance requirements
- Testing requirements
Although High Frequency PCB stackups cost more, they provide essential performance advantages for advanced applications.
9. FR4 vs High Frequency PCB Stackup Applications
FR4 PCB Applications
Suitable for:
- Consumer electronics
- Industrial controllers
- Power supply boards
- LED products
- General IoT devices
- Automotive control systems
High Frequency PCB Applications
5G Communication
Requirements:
- Low signal loss
- High-speed transmission
- Stable impedance
Automotive Radar
Frequency: 24GHz / 77GHz
Requires:
- Rogers materials
- Precise RF stackup design
Aerospace Electronics
Requirements:
- Extreme reliability
- Temperature stability
- Low dielectric variation
Satellite Communication
Requires:
- Microwave performance
- High-frequency stability
10. How to Choose Between FR4 and High Frequency PCB Stackup?
Engineers should consider:
Choose FR4 PCB Stackup When:
- Frequency is below several GHz
- Cost is a priority
- Standard performance is acceptable
- Large-volume production is required
Choose High Frequency PCB Stackup When:
- Frequency exceeds 5GHz
- RF performance is critical
- Low insertion loss is required
- Controlled impedance is necessary
A hybrid PCB stackup combining FR4 and Rogers materials is also widely used.
Example:
- Layer 1: RF Signal
- Layer 2: Rogers Material
- Layer 3: FR4 Core
- Layer 4: Digital Signal
This approach balances performance and cost.
11. Why Choose KingSunPCB for Custom PCB Stackup Manufacturing?
KingSunPCB provides professional custom PCB stackup design and manufacturing services for global customers.
Our capabilities include:
- Multilayer PCB fabrication
- FR4 PCB stackup design
- High Frequency PCB stackup manufacturing
- Rogers PCB fabrication
- Controlled impedance testing
- High-speed PCB solutions
Supported materials:
- FR4
- Rogers RO4003C
- Rogers RO4350B
- PTFE materials
- High TG laminates
With advanced manufacturing equipment and strict quality control systems, KingSunPCB supports applications including:
- Automotive electronics
- RF communication
- Industrial automation
- Medical electronics
- Aerospace systems
For engineers looking for a reliable FR4 PCB manufacturer or High Frequency PCB manufacturer, KingSunPCB provides customized solutions from prototype to mass production.
12. Frequently Asked Questions (FAQ)
Q1: What is the difference between FR4 and High Frequency PCB stackup?
FR4 PCB stackups use epoxy fiberglass materials and are suitable for general electronics, while High Frequency PCB stackups use low-loss materials such as Rogers PTFE for RF and microwave applications.
Q2: Is FR4 suitable for high-frequency applications?
Standard FR4 can support some high-frequency designs, but it becomes less effective at GHz frequencies due to higher dielectric loss and unstable Dk values.
Q3: Why are Rogers PCB stackups more expensive than FR4?
Rogers materials provide superior electrical performance, lower signal loss, and better impedance control, but their raw material cost and processing requirements are higher.
Q4: Can FR4 and High Frequency materials be combined in one PCB?
Yes. Hybrid PCB stackups combine FR4 and high-frequency materials to reduce cost while maintaining RF performance.
Q5: How much does a High Frequency PCB stackup cost?
A high-frequency PCB prototype typically costs between $150 and $800, while complex RF multilayer boards may exceed $3000 depending on specifications.
13. Conclusion
The choice between FR4 PCB stackup and High Frequency PCB stackup depends on application requirements, frequency range, signal integrity needs, and budget.
FR4 remains the best choice for cost-effective and general-purpose electronics, while High Frequency PCB stackups are essential for RF, microwave, 5G, radar, aerospace, and high-speed communication systems.
By selecting the correct stackup design and PCB materials, engineers can achieve better electrical performance, improved reliability, and optimized manufacturing costs.
KingSunPCB provides customized FR4 and High Frequency PCB stackup solutions for global electronics manufacturers. Contact our PCB engineering team for professional stackup design support and manufacturing services.