Printed circuit board Wikipedia. Part of a 1. 98. 3 Sinclair. ZX Spectrum computer board, a populated PCB, showing the conductive traces, vias the through hole paths to the other surface, and some mounted electronic components. I/51Jo7d8TEdL.jpg' alt='Program Proiectare Case' title='Program Proiectare Case' />Casa 3 Camere 65 mp cu Avans si Plata in Rate La Dezvoltator Casa ieftina pe care o propunem raspunde unei cerinte din ce in ce mai prezente pe piata imobiliara din. Electrocasnice De la Casa Nora iti poti echipa caminul cu toate electrocasnicele cuptoare, hote, plite, chiuvete, baterii, frigidere etc. Program Proiectare Case' title='Program Proiectare Case' />The shown board area uses through hole mounting of components. A printed circuit board PCB mechanically supports and electrically connects electronic or electrical components using conductive tracks, pads and other features etched from one or more layers of copper sheets laminated onto a non conductivesubstrate. Components are generally soldered onto the PCB to both electrically connect and mechanically fasten them to it. Advanced PCBs may contain components embedded in the substrate. Printed circuit boards are used in all but the simplest electronic products. They are also used in some electrical not electronic products, such as passive switch boxes and electric fans. Alternatives to PCBs include wire wrap and point to point construction, but these now are rarely used for mass production. PCBs require additional design effort to lay out the circuit, but manufacturing and assembly can be automated. Windows Activation Code 0X80070422. Program Proiectare Case' title='Program Proiectare Case' />CAD software is available to do much of the work of layout. Manufacturing circuits with PCBs is cheaper and faster than with other wiring methods, as components are mounted and wired in one operation. For mass production, large numbers of PCBs can be fabricated at the same time, and the layout only has to be done once. PCBs can be single sided one copper layer, double sided two copper layers on both sides of one substrate layer, or multi layer outer and inner layers of copper, alternating with layers of substrate. Multi layer PCBs allow for much higher component density, because circuit traces on the inner layers would otherwise take up space between components on the outer surface layers. The rise in popularity of multilayer PCBs with more than two, and especially with more than four, copper planes was concurrent with the rise in popularity of surface mount technology. The great reduction or total elimination of through holes in the body of a PCB makes inner layers more useful and the work of laying them out much simpler. The world market for bare PCBs exceeded 6. OvervieweditA basic PCB consists of a flat sheet of insulating substrate material, which gives it its mechanical strength and integrity, and a layer of copper cladding, i. Chemical etching through the copper cuts out areas so that the copper is divided into separate conducting regions, forming a circuit wiring pattern long, thin, sometimes serpentine lines called tracks or circuit traces, terminals or pads for connection of component leads or for external connections, contacts for vias, and other features such as solid conductive areas for EM shielding or other purposes. The tracks or traces function as uninsulated electrical wires. Their permanent fixation to the insulating substrate keeps them from touching each other and shorting essentially, adjacent conductive tracks etched from the same copper layer are insulated from each other by air. The surface of an exposed etched copper layer on a PCB may also be optionally coated with a protective coating that is electrically non conductive once these coatings were almost exclusively transparent green, but now other transparent colors including red, blue, and yellow are common. The coating is not mainly to insulate traces on the board from each other the air the coating displaces would normally do thatbut to seal out air to protect the copper from oxidation, to protect the copper from mild abrasion and from corrosion by chemical contamination, and to reduce the chances of solder shorts between traces or of undesired electrical contact with stray bare wires. For its function in helping to prevent solder shorts, the coating is called solder resist. The preceding basic PCB structure with one copper layer can be extended to a two layer or multi layer structure. A two layer board simply has etched copper on both sides instead of just one side. This allows wire line paths to cross each other without the use of jumper wires installed on the board like components, simply through a line on one side to a line being connected to on the other side that crosses over or under the opposing lines. The concept can be extended to multiple layers by dividing the substrate into thinner parallel layers and sandwiching additional copper layers between them. Conductors on different layers, whether there are just two layers or many, are connected with vias, which are essentially copper plated through holes that function as electrical tunnels through the insulating substrate. Through hole component leads sometimes also effectively function as vias. After two layer PCBs, the next step up is usually four layer of the four layers, often two are dedicated as power supply and ground planes, respectively, and the other two are used for signal wiring between components. However, this is only a popular pattern, not in any way a universal requirement, and each plane can be used in any way the designer chooses subject to his or her design rules. There are two ways of installing components on a PCB through hole and surface mount. A single PCB may use either or both methods they are not mutually exclusive, and often both are used on a single board. Though hole mounting, the original method and the only popular method until the mid 1. All or almost all components are typically inserted from one side, the component side and each of their leads is soldered to the board on the other side the solder side, where the etched pattern usually includes copper completely surrounding the holes. If the board has two or more layers, solder normally flows through the holes, around the component leads, to connect the copper of all layers where it exists at each lead thus, soldered component leads themselves can act as vias. For this to occur, the lead has to fit the hole closely enough to enable capillary action between the lead and the inner cylindrical surface of the hole. Surface mounting, which only became popular in the 1. Surface mounting cannot collaterally interconnect copper layers, so on PCBs with only surface mount components, all inter layer connections are by vias. While surface mounting can be done by point soldering for component sizes and lead pitches above certain practical minima, it is more commonly done by depositing solder pastea mixture of powdered solder and fluxover the solder pads in a precise pattern and at a precise thickness using a mylar mask, depositing the surface mount components usually by automated robotic equipment onto the PCB over the solder paste, which temporarily adheres the components to the board, and baking the board so adorned in a special oven to fuse the solder and permanently fix the electrical and mechanical connections. This is obviously a large scale manufacturing process not suitable to prototyping or very small limited production runs. PCBs with only through hole mounted components are now uncommon, though they were very common in machines built before the 1. PCBs were used before the 1.