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How much do you know about these common sense in pcb factories?
2021-10-02
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Author:Frank

How much do you know about these common sense in pcb factories?
Many people have worked in pcb factories for many years, especially those masters who have a good understanding of SMT equipment technology. Do you already know all the common sense about pcb factories? Come take a look, maybe there are some knowledge you don't know, please see the editor below for your sharing.
 smt factory workshop
smt factory production workshop

1. Generally speaking, the temperature specified in the production workshop of the smt factory is 25±3℃.

2. When printing solder paste, the materials and tools needed to prepare solder paste, steel plate, scraper, wipe paper, dust-free paper, cleaning agent, stirring knife.

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

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

pcb board

5. The main function of flux in soldering is to remove oxides, destroy the surface tension of molten tin, and prevent re-oxidation.

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

7. The principle of obtaining solder paste is first in, first out.

8. When the solder paste is opened and used, it must go through two important processes of temperature and stirring.

9. The common production methods of steel plate are: etching, laser, electroforming.

10. The full name of SMT is Surface mount (or mounting) technology, which means surface mounting (or mounting) technology in Chinese.

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

12. When making SMT equipment program, the program includes five parts, these five parts are PCBdata; Mark data; Feeder data; Nozzle data; Part data.

13. The melting point of lead-free solder Sn/Ag/Cu96.5/3.0/0.5 is 217C.

14. The controlled relative temperature and humidity of the parts drying box is <10%.

15. Commonly used passive devices (Passive Devices) include: resistance, capacitance, point sense (or diode), etc.; Active Devices (ActiveDevices) include: transistors, ICs, etc.

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

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

18. The types of electrostatic charge generated include friction, separation, induction, electrostatic conduction, etc.; the effects of electrostatic charge on the electronics industry are: ESD failure, electrostatic pollution; the three principles of electrostatic elimination are electrostatic neutralization, grounding, and shielding.

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

20. Exclusion ERB-05604-J81 No. 8 code "4" means 4 loops, the resistance value is 56 ohms. The capacitance of the capacitor ECA-0105Y-M31 is C=106PF=1NF=1X10-6F.

21. The full name of ECN in Chinese is: Engineering Change Notice; the full name of SWR in Chinese is: Special Requirements Work Order, which must be countersigned by relevant departments and distributed by the Document Center to be valid.

22. The specific contents of 5S are sorting, rectification, cleaning, cleaning, and quality.

23. The purpose of PCB vacuum packaging is to prevent dust and moisture.

24. The quality policy is: comprehensive quality control, implementation of the system, and providing quality required by customers; full participation and timely processing to achieve the goal of zero defects.

25. The three-not quality policy is: do not accept defective products, do not manufacture defective products, and do not discharge defective products.

 

26. Among the seven QC methods, 4M1H refers to (in Chinese): people, machines, materials, methods, and environment.

27. The components of solder paste include: metal powder, solvent, flux, anti-sagging agent, activator; by weight, metal powder accounts for 85-92%, and by volume metal powder accounts for 50%; among them, metal powder is mainly The composition is tin and lead, the ratio is 63/37, and the melting point is 183°C.

28. The solder paste must be taken out of the refrigerator to return to temperature during use. The purpose is to restore the temperature of the refrigerated solder paste to normal temperature to facilitate printing. If the temperature is not restored, the defects that are prone to occur after PCBA enters Reflow are tin beads.

29. The file supply modes of the machine include: preparation mode, priority exchange mode, exchange mode and quick connection mode.

30. SMT PCB positioning methods include: vacuum positioning, mechanical hole positioning, bilateral clamp positioning and board edge positioning.

31. The silk screen (symbol) is 272 resistor, the resistance value is 2700Ω, and the symbol (silk screen) of the resistance value 4.8MΩ is 485.

32. The silkscreen on the BGA body contains information such as manufacturer, manufacturer part number, specification, and Datecode/(LotNo).

33. The pitch of 208pinQFP is 0.5mm.

34. Among the seven methods of QC, the fishbone diagram emphasizes the search for causality.

37. CPK refers to: process capability under current actual conditions.

38. The flux begins to volatilize in the constant temperature zone for chemical cleaning.

39. The ideal mirror image relationship between the cooling zone curve and the reflux zone curve.

40. The RSS curve is heating → constant temperature → reflux → cooling curve.

41. The PCB material we are using is FR-4.

42. PCB warpage specification does not exceed 0.7% of its diagonal.

43. STENCIL laser cutting is a method that can be reworked.

44. At present, the diameter of the BGA ball commonly used on computer motherboards is 0.76mm.

45. The ABS system is absolute coordinates.

46. The error of ceramic chip capacitor ECA-0105Y-K31 is ±10%.

47. The voltage of Panasert Panasonic automatic placement machine is 3Ø200±10VAC.

48. SMT parts are packaged with tape-and-reel diameters of 13 inches and 7 inches.

49. SMT steel plate openings are generally 4um smaller than PCB PAD to prevent bad solder balls.

50. According to the "PCBA Inspection Regulations", when the dihedral angle is greater than 90 degrees, it means that the solder paste has no adhesion to the wave solder body.
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