PCB board (PrintedCircuitBoard) the support is an electronic component is electrically connected between the electronic component provider, the infrastructure it is almost all electronic products, in addition to its basic function of a variety of small electronic components secured , but the main function is to provide the above various electronic components are interconnected. As electronic devices become more complex, requiring more and more parts, resulting in PCB top line and accessories are also the more intensive. The substrate itself is made of an insulating board insulation, is not easy to bend the material into the production, the fine line can be seen on the surface of the material is copper, copper originally covering the entire board, and in the middle of the manufacturing process etching away the parts, he left to become part of the mesh of the fine line. These lines are called wire (conductorpattern) or said wiring, and a circuit for providing the electronic component on the PCB.
1.PCB sheet classification
PCB main categories are: single-sided, double sided, multilayer.
1, the single panel (Single-SidedBoards)
on the basic PCB, electronics components are concentrated on one side of the wire is concentrated on the other surface. Because the wire only in one side, so we call this PCB is called single panel (Single-sided). Because the single panel has many strict limitations in the design of the line, mainly: between wiring must not cross paths around alone, so only the circuits early use of such board, are now rarely seen.
2, bis panel (Double-SidedBoards)
that has a wiring on both surfaces of the circuit board. But to use on both sides of the wire, you must have the appropriate circuit connection between both sides in the job. Such a circuit is called a bridge between the guide hole. Guide hole in the PCB, metal filled or coated with holes, which can be connected to both sides of the wire. Since the area of double-sided board twice as big as the single panel, but also because the wiring may be staggered with each other, it is more suitable for use in more complex than the single-sided circuit.
3, multilayer (Multi-LayerBoards)
In order to increase the area of the wiring can, multilayer spend more single or double-sided wiring board. Multilayer panel using double the number of sheets, and an insulating layer placed between the stick firmly each plate. Represents the number of layers of the board have separate layers of wiring layers, usually the number of layers are even, and comprising two outermost. Most motherboards are 4-layer structure, but because layers of PCB board are closely integrated, generally less easy to see that the actual number, but if you look closely at the motherboard, maybe you can see it, but not this chance . So we method commonly used to separate layers of PCB thickness is to look it may additionally OK OK component.
2.PCB effect
Dynamic Characteristics
perceived identification process (a) System
(ii) reflecting the process
(c) a process corresponding to the resident memory
(d) process according to the control block constituting the concurrent execution of the maintenance and operation of the system control
3.PCB composition
(a) the description of
1, the process name process identification number or the
2, user name or user identification number
3 family relationship – process tree
(ii) a control information [ 123]
1, the current state of the
2, priority
3, the program start address
4, timing information
5 The communication information
(c) resource management information
1, occupied by the memory size and management data structure pointer
2, exchange information or cover
3 of Shared block size and a start address of the
4, I / O device-related information
Pointer 5, and related to the file system identifier
(iv) CPU reserve field the PCB tips
1, reference numeral automatic Component generated or existing components numeral canceled again
2, provided single-panel
3, the power cord is set in bold
4 prior to auto-routing, PCB package updating, as long as the original package right pop-footprint within the window to the new package numbers
5, placing the positioning hole
6, a drawing parameter
7, element rotation: X button: This element about reversed; the Y button: reversed vertical element
8, element properties
9, parts list
10, an electrical schematic diagram of the law testing