PCB in electronic equipment is the carrier of electronic components, provides mechanical support and electrical connections, and ensures the reliability of the electrical, thermal, and mechanical properties of electronic products. It provides solder-resist graphics for automatic soldering and identifying characters and graphics for electronic component installation, inspection, and maintenance. pcb components identification
PCB board by the pads, wires, silkscreen, insulating paint, positioning holes, through-holes, through-holes, and other elements of the composition:
(1) pads: pads are used to weld components or leads on the circuit board of copper foil, through the soldering furnace will be melted solder paste or wave soldering over the parts to be fixed;
(2) the conductor is used to weld components or leads on the circuit board.
(3) silkscreen: also known as white oil, text printing marked with the name of the part, location, and direction. PCB on the product model, version, manufacturer’s logo production batch number, and so on.(4) insulating varnish: insulating varnish’s role is to insulate, solder barrier, to prevent the PCB board surface contamination, butter and green oil favor more
(5) through-hole: PCB filled or coated with a small hole in the metal, it can be connected to the two sides of the wire, also known as VIA holes;
(6) through-hole: PCB board is filled with a small hole in the metal, it can be connected to the two sides of the wire, also known as VIA holes
(6) through-hole: used to insert and install through-hole components.
(7) Positioning holes: used to fix the PCB in the electronic equipment.
PCB symbols on the identification
R is the resistor;
L for the inductor coil (usually coil winding on the core ring, but also some have closed shell);
C for capacitors (tall standing up cylindrical, wrapped in plastic skin, above the cross indentation for electrolytic capacitors, flat is a chip capacitor);
UR for silicon-controlled rectifier;
VC for the control circuit has a power rectifier;
UF for the inverter;
UC for the converter;
UI is the inverter ;
M is motor;
MA for asynchronous motor;
MS for synchronous motor;
MD is direct current motor;
MW is wound rotor induction motor;
MC is a squirrel cage motor;
YM is a motorized valve;
YV is a solenoid valve
Two legs are diodes, three legs are transistors, many legs are integrated circuits, etc.
BOM reading: pcb components identification
BOM, Bill of material, in the production of electronic assembly, is a very important document, is the outcome of the development of electronic products, but also an important medium of communication between the various departments of the electronic enterprise, such as purchasing department according to the BOM can know what components to purchase, the production sector according to the BOM know that the assembly process of the circuit board, the number of components and the number of each installation. The production department knows the number and location of each component in the board assembly process according to the BOM. pcb components identification
To correctly complete the patch production, you must learn to read the BOM, read the BOM main attention to several aspects:
1. To be clear about the product model, version, such as VA-391 V3.2
2. Distinguish between the BOM which is SMC / SMD, which is THC;
(1) BOM description of the following words or letters are one of the SMT material “SMD, 0603, 0805, 1206, Chip, SMT, QFP, PLCC, BGA, SO”.
(2) Inserts generally have “DIP” words, but electrolytic capacitors are generally DIP-type, the BOM usually omits the “DIP” words, such as BOM line 31 of the electrolytic capacitors described as 6.8uF/400V, Ф8 * 15,105 ° C, 20%. C, 20%.
3. Some parts to look at the shape to know whether the SMD or DIP components.
(1) described as chip CAP 0.01F 50V +80%-20% SMD 0603 said: the capacitance is a chip ceramic capacitors, the capacitance of 0.01uF, withstand voltage 50V, error of +80%-20%, that is, the capacitance allows the range of: 0.018μF ~ 0.008μF, SMD 0603 type;
(2)Description for chip Resister 10 OHM 1/10W 5% 0603 means: the chip resistor resistance value is 100, power is 0.1 watt, error is +5% 0603 specification;
(3) described as Chipset Sis6326 H0 208-Pin PQFP said: the chip for the SIS company name for the 6326 version of the H0, 208 pins, PQFP type; pcb components identification