The advent of multi-layer PCBs
Historically, printed circuit boards were primarily characterized by their single or double-layered structure, which imposed constraints on their suitability for high-frequency applications owing to signal deterioration and electromagnetic interference (EMI). Nevertheless, the introduction of multi-layered printed circuit boards has resulted in notable advancements in signal integrity, electromagnetic interference (EMI) mitigation, and overall performance.
Multi-layered PCBs (Figure 1) consist of numerous conductive layers that are separated by insulating substrates. This design enables the transmission of signals and power planes in a sophisticated manner.
Multi-layer printed circuit boards (PCBs) are distinguished from their single or double-layer counterparts by the presence of three or more conductive layers that are separated by insulating material, commonly known as dielectric layers. The interconnection of these layers is facilitated by vias, which are minuscule conductive passageways that facilitate communication between distinct layers. The complicated design of multi-layer PCBs enables a greater concentration of components and intricate circuitry, rendering them essential for state-of-the-art technology.
Multilayer PCBs typically exhibit a high degree of rigidity due to the inherent challenge of achieving multiple layers within a flexible PCB structure. Electrical connections between layers are established through the utilization of several types of vias (figure 2), including blind and buried vias.
The configuration entails the placement of two layers on the surface to establish a connection between the printed circuit board (PCB) and the external environment. In general, the density of layers in printed circuit boards (PCBs) is even. This is primarily due to the susceptibility of odd numbers to issues such as warping.
The number of layers typically varies depending on the specific application, typically falling within the range of four to twelve layers.
Typically, the majority of applications necessitate a minimum of four and a maximum of eight layers. In contrast, apps such as smartphones predominantly employ a total of twelve layers.
Main applications
Multi-layer PCBs are used in a wide range of electronic applications (Figure 3), including:
●Consumer electronics, where multi-layer PCBs play a fundamental role providing the necessary power and signals for a wide range of products such as smartphones, tablets, gaming consoles, and wearable devices. The sleek and portable electronics that we depend on daily are attributed to their compact design and high component density
●In the field of telecommunications, the utilization of multi-layer PCBs facilitates the smooth transmission of voice, data, and video signals across networks, thereby guaranteeing dependable and effective communication
●Industrial control systems heavily depend on multi-layer printed circuit boards (PCBs) due to their capacity to effectively manage intricate control systems, monitoring mechanisms, and automation procedures. Machine control panels, robotics, and industrial automation rely on them as their fundamental support system
●Multi-layer PCBs are also relevant for medical devices, since they are crucial for ensuring precision, dependability, and compactness. Diagnostic equipment, patient monitoring systems, and life-saving medical devices are significantly influenced by their important role.
Benefits and advantages
Multi-layer PCBs provide several benefits and advantages in high-frequency applications, including:
●Enhanced signal integrity: Multi-layered PCBs facilitate controlled impedance routing, minimizing signal distortion and ensuring reliable transmission of high-frequency signals. The lower signal interference of multi-layer printed circuit boards result in improved performance, velocity, and dependability
●Reduced EMI: By utilizing dedicated ground and power planes, multi-layered PCBs effectively suppress EMI, thereby enhancing system reliability and minimizing interference with neighboring circuits
●Compact Design: With the ability to accommodate more components and complex routing schemes, multi-layered PCBs enable compact designs, crucial for space-constrained applications such as mobile devices and aerospace systems.
●Improved Thermal Management: Multi-layered PCBs offer efficient heat dissipation through the integration of thermal vias and strategically placed copper layers, enhancing the reliability and lifespan of high-power components.
●Design Flexibility: The versatility of multi-layered PCBs allows for greater design flexibility, enabling engineers to optimize performance parameters such as impedance matching, signal propagation delay, and power distribution.