This layer constitutes the core of the PCB. Once the designer has drafted the circuit using various design software, a specialized machine engraves the copper foil layer according to the design specifications. This process selectively removes unwanted portions, thereby forming a complete circuit. Concurrently, various components such as chips, resistors, capacitors, inductors, connectors, and fuses are soldered or mounted onto the PCB. This integration with the copper foil layer completes the circuit assembly.
Usually, a PCB board consists of two layers located on the upper and lower surfaces of the substrate. The circuits on these layers differ due to circuit design requirements and safety considerations. For instance, power supply lines and grounding lines are typically isolated on separate layers, enhancing circuit integrity.
In more complex scenarios, a single layer may not accommodate all necessary lines or adequately control the circuit (e.g., components with stringent impedance requirements). In such cases, multi-layer PCBs are employed. These consist of multiple single-layer PCBs stacked together, allowing different circuits to be designed on separate layers to meet complex circuitry demands. Common configurations for multi-layer PCBs include 2 layers, 4 layers, 6 layers, 8 layers, 10 layers, and beyond.
Identifying whether a PCB is multi-layered is relatively straightforward: shine a light through the board and observe areas where copper is absent on the upper and lower surfaces. If these areas appear translucent, it indicates the presence of additional internal layers, reducing transparency. Some experienced developers can even estimate the number of layers through visual inspection, although accurately counting them remains challenging.
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The substrate material of a PCB board
There is no unified standard for the color of PCB boards, so it is not accurate to say that PCBs of other colors are inherently better than the green ones. However, green is the most commonly used color in PCB design because its surface is not dazzling. Some manufacturers, aiming to highlight their designs, often opt for different colors on higher-quality products. For instance, they may use purple, yellow, black, or other colors of ink to achieve distinctive visual effects. This might explain why some feel that “other colors are better than green.”
First and foremost, the number of layers in a PCB is determined according to the customer’s industry needs. For example, when a customer designs a circuit board for a motherboard or a graphics card, they might only require a few layers. Despite this, all boards undergo rigorous reliability testing before mass production, ensuring that even 4-layer or 2-layer boards can meet performance requirements. Since the number of layers in a PCB might not be well understood by most businesses, it is not crucial information for practical purchasing decisions, and there is no need to overly constrain yourself in this regard.
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