PCB (Printed Circuit Board) is one of the most fundamental yet critical components in electronic systems. It not only hosts various electronic components but also plays key roles in power distribution, signal transmission, and grounding reference. In the past, due to lower system speeds and less dense signal paths, the impact of PCBs on overall performance was relatively limited.Many distributors offer a wide range of electronic components to cater to diverse application needs.
However, as data exchange between GPUs, CPUs, switch chips, network cards, and storage controllers becomes increasingly frequent, high-speed links are rapidly expanding within boards, between boards, and even across racks. As a result, PCB importance has significantly increased, becoming a key factor in system performance. This is also reflected in cost: while low-speed PCBs may cost just over a thousand RMB per square meter, high-end AI server PCBs can reach tens of thousands per square meter.
PCB Structure and Classification
Structurally, a PCB is not a single material but a composite system made up of multiple elements. Its core components include copper conductor layers for signal transmission and power distribution, dielectric layers (such as fiberglass or quartz cloth combined with resin systems) for insulation and support, and core materials and prepregs that form the multilayer structure through lamination. In addition, vias and interconnect structures are used to electrically connect different layers.
From a classification perspective, PCBs can be divided into single-layer, double-layer, and multilayer boards. Based on wiring density, they can be further categorized into standard multilayer boards and HDI (High-Density Interconnect) boards. HDI technology achieves higher routing density through finer trace widths, smaller vias, and advanced structures such as microvias, blind vias, and buried vias, making it a key solution for high-end electronic systems.
Why Are PCB Requirements Increasing?
As data transmission speeds continue to rise and device sizes shrink, PCBs are required to handle faster data transfer within more limited spaces. In modern systems, the number of high-speed signal links has surged, and every trace on a PCB must meet strict requirements for impedance control, low loss, and continuous return paths. Unlike in the past, where design margins could mask issues, even minor deviations in materials or manufacturing can now be amplified in high-speed environments and directly impact system performance.
Key Challenges in High-Speed PCBs
During high-speed signal transmission, PCBs face several critical challenges:
Loss: Signal amplitude decreases over distance, affecting signal integrity
Reflection: Impedance discontinuities cause waveform distortion
Crosstalk: Dense routing leads to interference between adjacent signals
Return Path Issues: Discontinuous reference planes increase noise and delay
Resonance Effects: Excess metal in vias can introduce unwanted resonance
These issues become more pronounced at high frequencies and directly affect system stability and reliability.
Key Influencing Factors: Materials, Structure, and Process
PCB performance is influenced by multiple factors:
Materials:
Dielectric constant and loss characteristics of laminates determine signal quality; fiberglass and resin systems affect stability and uniformity
Copper Properties:
At high frequencies, current flows on the conductor surface, making copper roughness and profile critical to loss and impedance control
Layer Count and Stack-Up Design:
More layers enable better signal segregation but require stricter reference plane management
Interconnect Methods:
Through vias, blind vias, buried vias, and microvias impact signal path length, reflection, and routing density
Optimization Strategies for High-Speed Design
To address these challenges, PCB design continues to evolve toward higher performance:
Material Optimization: Use low-loss, high-stability dielectric materials
Copper Improvement: Adopt low-roughness copper foils to reduce high-frequency loss
Stack-Up Optimization: Properly separate signal, power, and reference layers to ensure continuous return paths
Advanced Interconnects: Utilize HDI structures and optimized via designs to minimize reflection and parasitic effects
Conclusion
The core challenge of high-end PCB design lies in ensuring accurate and stable signal transmission under conditions of higher speed, higher density, and greater structural complexity. As data rates continue to increase, the influence of materials, structure, and manufacturing precision on system performance becomes more significant. PCBs have evolved from passive carriers into critical foundations that determine system performance, and their technological advancement will continue to drive innovations in AI servers, high-speed communications, and advanced computing platforms.