Double-sided High-speed PCB

Description

1. Basic Parameter Analysis
Based on your requirements, the high-frequency PCB design includes the following key parameters:
Number of Layers: Double-layer (2-layer)
A double-layer PCB features two conductive layers, ideal for high-frequency circuits with simple structures. It offers compact design and excellent signal transmission capabilities.
Dimensions: 25mm x 100mm
The physical dimensions are 25mm wide and 100mm long, suitable for compact devices or modular designs, especially in scenarios like communication, radar, and wireless modules.
Board Thickness: 1.0mm
A thickness of 1.0mm provides good mechanical strength and stable high-frequency signal transmission. It is also appropriate for space-constrained designs, avoiding issues caused by excessive or insufficient board thickness.
Copper Thickness: 1oz (approximately 35μm)
The 1oz copper thickness is a standard choice that meets the needs of signal and power transmission. In high-frequency PCBs, it reduces signal attenuation and provides good thermal conductivity.
Surface Finish: Immersion Gold
Immersion gold (ENIG) ensures a smooth soldering surface, reducing the risk of poor solder joints. Its excellent oxidation resistance and conductivity make it ideal for maintaining signal integrity in high-frequency PCBs.
2. Characteristics and Design Considerations of High-frequency PCBs
High-frequency PCBs are widely used in RF and microwave applications such as wireless communication, radar systems, and navigation devices. Key considerations for high-frequency PCB design include:
Material Selection
Material choice is critical for high-frequency PCBs. Common options include:
PTFE (Polytetrafluoroethylene) Materials: Such as Rogers 4350B, 5880, known for low dielectric constant (Dk) and low dielectric loss (Df).
Ceramic-filled Materials: Used in scenarios with stringent dielectric requirements.
Hybrid materials like FR4 with high-frequency layers, balancing performance and cost.
Impedance Control
Impedance matching is crucial to avoid signal reflection and distortion. Key factors include:
Trace width, thickness, and spacing.
Dielectric thickness and material properties (Dk).
Ground plane continuity to ensure the shortest return path.
Trace Design
High-frequency traces are affected by transmission line effects. Considerations include:
Trace Width Calculation: Based on target impedance (e.g., 50Ω or 75Ω) and dielectric material.
Bend Handling: Avoid sharp or 90-degree angles; use curved or 45-degree bends to reduce signal loss.
Differential Pairs: Maintain equal length and spacing for differential signals to reduce crosstalk.
Layer Structure Design
Double-layer boards typically consist of a signal layer and a ground layer. Ground layer integrity is critical.
The distance between the signal and ground layers should meet impedance design goals.
Thermal and Mechanical Strength
High-frequency circuits generate heat. Copper planes or board thickness can be optimized for better thermal performance. A 1.0mm thickness is a good compromise between mechanical strength and heat dissipation.
Surface Finish
Immersion gold provides excellent conductivity, oxidation resistance, and soldering reliability, enhancing signal integrity and board lifespan.
3. Process Optimization Recommendations
Pad Design
Ensure smooth pad edges to avoid electromagnetic interference (EMI).
Consider pad size and via layout for mechanical strength and soldering stability.
Via Design
Optimize copper plating thickness in vias to reduce signal loss.
Minimize the use of vias for critical signals to reduce parasitic effects.
Shielding Design
High-frequency circuits are prone to external interference. Use shielding layers or shields to isolate noise.
Fill unused areas with grounded copper pours.
Testing and Verification
Perform strict impedance testing, signal integrity testing (SI), and EMC/EMI testing to ensure design performance.
4. Applications
Double-sided immersion gold high-frequency PCBs are primarily used in:
Wireless Communication: Base stations, Wi-Fi modules, Bluetooth devices.
Radar Systems: Automotive radar, weather radar.
Navigation Devices: GPS modules, satellite communication.
Microwave Devices: Filters, amplifiers, and other high-frequency components.