SMT Necessary Know Question

1. In general, the temperature specified by the SMT workshop is 25±3°C;

2. When solder paste is printed, the required materials and tools are solder paste, steel plate, scraper, wiping paper, dustless paper, cleaning agent, and mixing knife;

3. The commonly used Sn paste alloy composition is Sn/Pb alloy, and the alloy ratio is 63/37;

4. The main components of the solder paste are divided into two major parts of tin powder and flux.

5. The main role of flux in welding is to remove oxides, destroy the surface tension of molten tin, and prevent reoxidation.

6. The ratio of the volume of tin powder particles and Flux (flux) in the solder paste is about 1:1, and the weight ratio is about 9:1;

7. The principle of the use of solder paste is first-in, first-out;

8. When the paste is used in Kaifeng, it must go through two important processes to warm and stir;

9. The common production methods for steel plates are: etching, laser, electroforming;

10. The full name of SMT is Surface mount (or mounting) technology, which means surface adhesion (or placement) technology;

11. The full name of ESD is Electro-static discharge, which means electrostatic discharge in Chinese;

12. When making an SMT device program, the program includes five major parts. The five parts are PCB data; Mark data; Feeder data; Nozzle data; Part data;

13. The melting point of lead-free solder Sn/Ag/Cu 96.5/3.0/0.5 is 217C;

14. The relative humidity and temperature of the part drying oven is < 10%;

15. Passive Devices are commonly used: resistance, capacitance, point (or diode), etc. Active devices include: transistors, ICs, etc.

16. The commonly used SMT steel plate is made of stainless steel;

17. The thickness of commonly used SMT steel plate is 0.15mm (or 0.12mm);

18. Electrostatic charges are generated by friction, separation, induction, and static conduction. The effects of electrostatic charges on the electronics industry are: ESD failure and electrostatic pollution. The three principles of static elimination are electrostatic neutralization, grounding, and shielding.

19. Inch dimensions length x width 0603 = 0.06inch * 0.03inch, metric size length x width 3216 = 3.2mm * 1.6mm;

20. The 8th code “4” of the ERB-05604-J81 exclusion is represented as 4 loops and the resistance value is 56 ohms. The capacitance of the capacitor ECA-0105Y-M31 is C=106PF=1NF=1X10-6F;



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