Common Knowledge of Pick and Place Machine and SMT Production (3)

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

32.The silk screen on the BGA body contains information such as the manufacturer, manufacturer's material number, specification and Date code/(Lot No);

33.The pitch of 208pinQFP is 0.5mm;

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

35.CPK refers to: Process Capability under Current Actual Conditions;

36.The flux starts to volatilize in the constant temperature zone for chemical cleaning;

37.Ideal cooling zone curve and reflow zone curve mirror image relationship;

38.The solder paste of Sn62Pb36Ag2 is mainly used on ceramic boards;

39.Rosin-based flux can be divided into four types: R, RA, RSA, RMA;

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

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

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

43.Laser cutting by STENCIL can be reworked;

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

45.The ABS system is an absolute coordinate;

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

47.The PCB of the computer currently in use is made of: glass fiber board;

48.The diameter of tape and reel for SMT parts packaging is 13 inches and 7 inches;

49.The opening of the SMT general steel plate is 4um smaller than that of the PCB PAD to prevent the phenomenon of bad solder balls;

50.According to the "PCBA Inspection Specification", when the dihedral angle > 90 degrees, it means that the solder paste has no adhesion to the wave soldering body;

51.After the IC is unpacked, if the humidity on the display card is greater than 30%, it means that the IC is damp and absorbs moisture;

52.The weight ratio and volume ratio of tin powder and flux in the solder paste composition are correct 90%:10%, 50%:50%;

53.The early surface mount technology originated from the military and avionics fields in the mid-1960s;

54.At present, the contents of Sn and Pb in the most commonly used solder paste for SMT are: 63Sn 37Pb; the eutectic point is 183°C;

55.The feeding distance of the common paper tape tray with a bandwidth of 8mm is 4mm;

56.In the early 1970s, a new type of SMD appeared in the industry, which was a "sealed footless chip carrier", often replaced by LCC;

57.The resistance value of the component marked 272 should be 2.7K ohms;

58.The capacitance of 100NF components is the same as that of 0.10uf;

59. The most commonly used electronic component material for SMT is ceramics;