110 Points the most Useful Knowledge of SMT (Part 2) ,

Continue With Part 1 .

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

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

39. The ideal cooling zone curve and the recirculation zone curve mirror relationship;

40. The RSS curve is temperature rise → 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. STENCIL’s laser cutting is a method that can be reworked;

44. The BGA ball diameter currently used on computer motherboards is 0.76mm;

45. The ABS system is absolute coordinates;

46. Ceramic chip capacitor ECA-0105Y-K31 error is ±10%;

47. Panasert automatic placement machine with a voltage of 3Ø200 ± 10VAC;

48. SMT parts are packaged with a tape reel having a diameter of 13 inches and 7 inches;

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

50. According to the “PCBA inspection regulations”, when the dihedral angle is >90 degrees, it means that the solder paste has no adhesion to the wave soldering body;

51. After the IC unpacking, the humidity on the humidity display card is greater than 30%, indicating that the IC is damp and moisture-absorbing;

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

53. Early surface-adhesive technology originated in the military and avionics fields in the mid-1960s;

54. At present, the content of solder pastes Sn and Pb most commonly used in SMT is: 63Sn+37Pb;

55. A common paper tape tray with a bandwidth of 8 mm has a feed pitch of 4 mm;

56. In the early 1970s, a new type of SMD in the industry was a “sealed footless chip carrier”, often referred to as HCC;

57. The resistance of the component with symbol 272 shall be 2.7K ohms;

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

59. The eutectic point of 63Sn+37Pb is 183 ° C;

60. The most used electronic parts for SMT are ceramics;

61. The reflow oven temperature curve has the highest curve temperature of 215C;

62. When the tin furnace is inspected, the temperature of the tin furnace is 245C;

63. SMT parts are packaged with a tape reel having a diameter of 13 inches and 7 inches;

64. The opening pattern of the steel plate is square, triangular, round, star, and the shape of the cone;

65. The computer-side PCB currently used is made of: fiberglass board;

66. Which type of substrate ceramic plate is used for the solder paste of Sn62Pb36Ag2;

67. The rosin-based flux can be divided into four types: R, RA, RSA, RMA;

The Next 3 part will be showed later ,thanks for your reading .