1. Printed circuit boards (PCBs) are found in nearly every electronic device. If a device contains electronic components, they are all mounted on PCBs of various sizes.

2. Beyond securing different small components, the primary role of the PCB is to establish electrical connections between the components on its surface.

3. As electronic devices grow increasingly complex, the number of components required rises, resulting in denser circuits and parts on the PCB.

4. A standard PCB typically appears as follows: the bare board (devoid of components) is often referred to as a “Printed Wiring Board (PWB).”

5. The substrate of the board is constructed from materials that are both insulating and thermally resistant, while also being rigid.

6. The thin circuitry visible on the surface is made from copper foil. Initially, the copper foil covered the entire board, but during manufacturing, portions were etched away, leaving behind a network of fine lines.

7. These lines are known as conductor patterns or wiring, serving to create circuit connections for the components on the PCB.

Here’s a refined version of your article, keeping the original meaning, clarity, and technical accuracy intact:

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1. To secure the components on the PCB, we solder their pins directly onto the traces. In the most basic type of PCB (single-sided), components are concentrated on one side while the traces are on the opposite side. Consequently, we must create holes in the board to allow the pins to pass through to the other side, where they are soldered. This results in the two sides of the PCB being referred to as the Component Side and the Solder Side.

2. If there are components on the PCB that need to be removed or reinstalled after production, a socket will be utilized for installation. Since the socket is directly soldered to the board, components can be easily detached and reattached. The ZIF (Zero Insertion Force) socket, shown below, facilitates effortless insertion and removal of components (in this case, the CPU). The locking lever next to the socket secures the component once it is inserted.

3. To connect two PCBs, we typically use an edge connector, commonly known as a “golden finger.” The golden fingers have multiple exposed copper pads, which are integral to the PCB’s wiring. When connecting, we insert the golden fingers from one PCB into the corresponding slot on the other PCB (commonly referred to as the expansion slot). In computers, graphics cards, sound cards, and similar interface cards are connected to the motherboard using golden fingers.

4. The green or brown color on the PCB represents the solder mask. This insulating layer protects the copper traces and prevents components from being soldered incorrectly. A silkscreen layer is printed on top of the solder mask, typically featuring white text and symbols to indicate the positions of each component. This printed surface is also known as the legend surface.

5. Single-Sided Boards: As previously mentioned, in the most basic PCBs, components are concentrated on one side while traces are on the other. Since traces are only on one side, this type of PCB is termed single-sided. The design of single-sided boards imposes strict limitations on circuit layout (wiring cannot cross and must take separate paths), which is why this type is primarily used in early circuits.

6. Double-Sided Boards: These circuit boards feature wiring on both sides. However, to connect traces on both sides, proper circuit connections must be established, known as vias. A via is a small hole filled or coated with metal on the PCB, enabling connections between traces on both sides. As double-sided boards offer double the wiring area of single-sided boards and allow for interleaved traces, they are better suited for more complex circuits than their single-sided counterparts.

7. Multi-Layer Boards: To expand the wiring area further, multi-layer boards consist of several single or double-sided wiring layers. These boards are constructed from multiple double-sided layers, with insulating material between each layer, then bonded together. The number of layers refers to the number of independent wiring layers, typically even and inclusive of the two outermost layers. Most motherboards feature 4 to 8 layers, though technically, PCBs can reach nearly 100 layers. While many supercomputers utilize multi-layered motherboards, the increasing use of clusters of standard computers has led to a decline in the need for super-multilayered boards. The internal layers of the PCB are closely integrated, making it difficult to ascertain the total number, but a close inspection of the motherboard may reveal this information.

8. As mentioned, vias in a double-sided board must penetrate the entire board. However, in multi-layer boards, if we only need to connect certain traces, vias can consume trace space in other layers. Technologies like buried vias and blind vias address this issue by penetrating only a few layers. Blind vias connect several internal PCB layers to the surface without traversing the entire board, while buried vias connect only internal layers and remain invisible from the surface.

9. In multi-layer PCBs, each layer is directly connected to ground and power. Thus, we categorize each layer as a signal layer, power layer, or ground layer. If components on the PCB require different power supplies, these PCBs usually contain more than two layers for power and traces.