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Training materials for SMT mounter operators

author: click::552 Publication time:2022-08-03

Operator's post requirements: 1. Be familiar with various electronic materials and their parameters; 2. Understand and memorize all relevant management systems and standards; 3. Be familiar with post work projects and strictly follow the operation standards; 4. Understand SMT production process, and have relevant quality and management knowledge; 5. Skilled operation of the responsible machine, master the performance of the equipment and manage the machine and spare parts; 6. Have the ability to judge and analyze general quality abnormalities and good communication and feedback; 

II. Training contents: 1. Training knowledge of electronic components 1.1 Structure, specifications and parameters of SMD resistor and capacitor 1.1.1 Resistor: in the circuits of electrical appliances and electronic equipment, in order to control the voltage and current of the circuit or make the amplified voltage or current achieve its working effect, a component with a certain resistance value is needed; The main parameters are: nominal value, allowable deviation, rated power, temperature coefficient, voltage coefficient, maximum working voltage, noise electromotive force, high frequency characteristics and aging coefficient; A) circuit code: r; Unit of resistance: ohm (ω), conversion: 1g ω = 1000mω; 1m ω = 1000kω = 10000000ω b) SMD resistor package: 0402, 0603, 0805, 1206, 1812, etc. C) Nominal value: there are commonly specified values, such as 1k~2k, 1k5 and 1k8 between 1k and 2k, and other parameters need to be customized. D) Allowable deviation of resistance value is shown in the following table: Allowable resistance value The maximum power that can be sustained by long-term continuous work under certain atmospheric pressure (87kpa~107kpa) and specified temperature (-55℃ ~ 125℃); F) Voltage coefficient: a physical quantity that indicates the thermal stability of the resistor changes with temperature; Indicates the relative change of resistance value corresponding to every 1 degree increase in temperature; G) voltage coefficient: indicates the relationship between resistance and voltage, and indicates the stability of applied voltage; H) maximum working voltage: the voltage at which the resistor will not be overheated or damaged by electric breakdown for a long time; 1.1.2 Capacitor: It has the function of charging and discharging, and can be used for tuning, DC isolation, filtering, AC bypass, etc. The specific parameters are: nominal capacity and allowable deviation, rated working voltage, insulation resistance, temperature coefficient, capacitor loss, frequency characteristics, etc. A) Capacitor code: C, capacity units: Farah, microfarad, Nafa, Pifa; Micro-method is generally used for SMD electrolytic capacitor units, and skin method is generally used for SMD monolithic multilayer capacitor units; Conversion: 1 farad = 1,000,000 microfarad = 1,000 nanofarad = 1,000,000 picofarad b) The electrolytic capacitor is packaged in a cylindrical shape; Single-layer capacitors are rectangular: packaged with: 0402, 0603, 0805, 1206, 1812, etc. c) Nominal capacity: convenient for production and actual needs, and the state has stipulated a series of capacity values as product standards; Capacity error: 0.05%, 0.1%, 0.25%, 0.5%, 1%, 2%, 5%, 10%, 20%, ±30% D) Rated working voltage: refers to the highest voltage that can work continuously and reliably within the specified temperature range, and The standard rated voltages are: 6.3V, 10V, 16V, 25V, 35V, 50V, 63V, 100V, 160V, 250V, 300V, 400V, 450V, 500V, 630V, 1000V, 1600V, 2000V and 250V. F) Leakage current: the capacitor medium is not insulated, and there will always be some leakage. When the leakage current is large, the capacitor will heat up, and in serious cases, it will be damaged (all capacitor material parameters have leakage current standards); G) Frequency characteristic: the property that the capacitance and other parameters of the capacitor change with the frequency of the electric field when it works in the AC circuit (high frequency operation); H) Tangent foot of capacitor loss: indicates the energy loss of capacitor; 1.2 Structure and model of SMD transistor: generally, it has two or three pins, crystal diode and transistor, and its structure is composed of one or two PN junctions, which are packaged as follows: crystal diode has cylindrical shape and rectangular shape (with polarity); Transistor is SOT-23/25/89/143 1.3 SMD inductor, connector, transformer, etc. SMD inductor: 0603, 0805, 1206, etc. are packaged, and high-power inductor is also connected in cylindrical shape (according to the shape of magnetic core): mainly external shape, pin number, pin spacing, etc. Transformer: divided into primary winding and secondary winding. Attention must be paid to the direction of mounting. 1.4 IC chip package IC package includes BGA, SOP, SOJ, SOL, PQFP, LQFP, PLCC, DIP, etc. 1.5 Packaging, storage and protection of electronic components of SMD: electronic components are packaged in bulk, tape, tray, etc., and the effective storage time is one month. The environment requires that the temperature (24 3℃) and humidity (44℃)