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PCB circuit board basics

Time: 2022-06-06 Hits: 15
PCB (Printed circuit board, PCB) will appear in almost every electronic device which. If the device has a kind of electronic components, they are also set in various sizes on the PCB. In addition to a variety of small parts is fixed, PCB's main function is to provide top of the electrical connections between components. As electronic devices become increasingly complex, requiring more and more parts, PCB and components on top of the line more and more dense. Standard PCB looks like this. Bare board (no top part) is also often referred to as "printed circuit board Printed Wiring Board (PWB)".

The board itself is insulated substrate is not easy to bend the material into the production. Can be seen on the surface of the small line material is copper, copper foil is covered in the original board, and in most of the manufacturing process was etching away, leaving to become part of a network of fine lines. These lines are called conductors (conductor pattern) or said wiring, and components used to provide circuit connections on the PCB.

Fixed to the part above the PCB, we will pin them directly soldered wiring. At the most basic PCB (single panel), the parts are concentrated in one side, wire is focused on the other side. Way we need holes in the board, so the pin can pass through the board to the other side, so part of the pin is welded on the other surface. Because of this, PCB's were called positive and negative parts surface (Component Side) and the welding surface (Solder Side).

If the PCB on top of some parts, need to be removed after completion of production or putting it back, then the parts will be used when installing socket (Socket). As the jack is soldered directly on the board, removable parts can be arbitrary. See below is the ZIF (Zero Insertion Force, dial zero insertion force) receptacles, which allows parts (in this case is the CPU) can be easily inserted into the socket, also can be removed. Socket next to the lever, in your part will be inserted into its fixed.

If you want two PCB interconnected, generally we will use commonly known as "Goldfinger" edgeconnectors(edge connected). Goldfinger contains many of the bare copper pad, the copper pad is in fact a part of PCB layout. Normally connected, we will be one of a finger on the PCB on the PCB inserted into another piece of the appropriate slot (generally called a slot Slot). In a computer, such as video card, sound card or other similar interface cards are connected by the finger to the motherboard.

Green or brown on the PCB, the solder mask paint (solder mask) color. This layer is the insulating layer of protection can protect the copper, it can not prevent the parts being welded to the right place. Also in the solder layer will be printed on the surface layer of screen printing (silk screen). Usually this will be printed above the text and symbols on the (mostly white), to mark out the parts in position on the board. Screen printing is also called icon surface area (legend).

Single Panel (Single-Sided Boards)

We have just mentioned, the basic PCB, parts focused on one side, wires are concentrated on the other side. Because only in wires on one side, so we call this is called single-sided PCB (Single-sided). Single-panel design lines because there are many strict restrictions (because only one side, the wiring around the room and must not cross the path of its own), so only until the early use of such a circuit board.

Double-sided (Double-Sided Boards)

This board has a wiring on both sides. But to use the wire on both sides, both sides must be in the proper circuit connection between Caixing. This circuit is between a "bridge" called the pilot hole (via). Pilot hole in the PCB, the holes filled or coated with metal, it can be connected to the wire with both sides. Because double-sided single-panel large area than doubled, and because the interwoven wiring can (you can go around the other side), it is more suitable for use in more complex than the single-sided circuit.

Multilayer (Multi-Layer Boards)

In order to increase the wiring area can, multilayer spend more single or double-sided wiring board. Multilayer film with a few double-sided, and in between each board into the insulating layer after layer of sticky prison (laminated). On behalf of the board of the layers are separate layers of wiring layers, usually layers are even, and includes the outermost layers. Most of the board are 4 to 8-layer structure, but technically can be done nearly 100 layers of PCB board. Most large-scale use of supercomputers rather multi-layered board, but because such a computer can already use many common computer cluster replaced gradually over plywood has not been used. Because the PCB levels are closely integrated, the general is not easy to see that the actual number, but if you look closely at the motherboard, may be seen.

We just mentioned the pilot hole (via), if applied to double-sided board, then we all went through the entire board. But in the multilayer which, if you want to connect some of the lines, then the holes may be a waste of some of the other layers of line space. Buried (Buried vias) and the blind holes (Blind vias) technology avoids this problem because they only penetrate several layers of them. Blind hole is to the surface layers of the internal PCB and PCB connections, do not have to penetrate the entire board. Buried vias to connect only within the PCB, so just from the surface is not apparent.

In multilayer PCB, the entire layer are directly connected to the ground and power. So we will all levels of classification signal layers (Signal), the power level (Power) or ground floor (Ground). If you need different parts on the PCB power supply, usually have two or more of these PCB power and wire layer.