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20 Known Issues for SMT and PCBA
Jan 18, 2018
  1. In general, the temperature specified by SMT workshop is 25 ± 3 ℃; 2.

  2. Solder paste, steel plate, scraper, wipe paper, dust-free paper, cleaning agent, stirring knife when the solder paste is printed.

  3. 3. Commonly used solder paste alloy composition is Sn / Pb alloy, and the ratio of alloy 63/37;

  4. Solder paste in the main component is divided into two parts: 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 further oxidation. 6. Solder tin powder particles and Flux (flux) volume ratio  of about 1: 1, the weight ratio of about 9: 1.

7. Solder paste access principle is FIFO; 

8. Solder paste in Kaifeng use, to go through two important processes: temperature ﹑ stirring. 

9. Common production methods of steel plate: etching, laser, electroforming; 

10. SMT's full name is Surface mount (or mounting) technology, the Chinese meaning of surface adhesion (or placement) technology; 

11. ESD's full name is Electro- static discharge, the Chinese meaning of electrostatic discharge; 12. Production SMT equipment program, the program includes five parts, the five parts for PCB data; Mark data; Feeder data; Nozzle data; Part data; 

13. The lead-free solder Sn / Ag / Cu has a melting point of 217 ° C at 96.5 / 3.0 / 0.5. Lead 63/37 is 183 degrees, 55/45 187-202. 

14. Parts of the oven control relative humidity <10%; 

15. The commonly used passive components (Passive Devices) are: resistors, capacitors, Inductor (or diode), etc .; active components (Active Devices)

There: transistors, ICs, etc .; 

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

17. The thickness of commonly used SMT steel plate

0.15mm (or 0.12mm); 

18. The type of electrostatic charge generated by friction, separation, induction, electrostatic conduction, etc .; electrostatic charge on the electronics industry as: ESD failure, electrostatic pollution; static elimination of the three principles of static And ﹑ ground ﹑ shield. 

19. Inch Size L x W 0603 = 0.06inch * 0.03inch, Metric Dimensions L x W 3216 = 3.2mm * 1.6mm; 

20. Exhaust ERB-05604-J81 Code No. 4 "4" The value is 56 ohms. Capacitance ECA-0105Y-M31 capacitance value is C = 106PF = 1NF = 1X10-6F;


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