Introduction to SMT Common Knowledge (2)

Source:Junze Electronics      Browse:      Time:2018-09-20

Nowadays, SMT electronic components have been deeply applied to all walks of life, and each electronic manufacturer has its own strengths. Let us continue to learn the common knowledge of SMT!

31. The silkscreen (symbol) is a resistance of 272, the resistance is 2700Ω, and the sign of the resistance of 4.8MΩ (screen printing) is 485. SMT

32. The silkscreen on the BGA body contains information such as the manufacturer, manufacturer's part number, specifications, and Datecode/(Lot No).

33. The pitch of the 208pinQFP is 0.5mm.

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

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

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

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

38. Sn62Pb36Ag2 solder paste is mainly used for ceramic plates;

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

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 commonly used on computer motherboards is currently 0.76mm;

45. The ABS system is absolute coordinates;

46. ​​Ceramic chip capacitance ECA-0105Y-K31 error is ±10%; SMT

47. The PCB of the computer currently used is made of: fiberglass board;

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 Code", 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 paste Sn and Pb most commonly used in SMT is: 63Sn 37Pb; eutectic point is 183 °C

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 SMD appeared in the industry as a “sealed footless chip carrier”, often referred to as LCC;

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

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

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 245 °C;

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

64. There is no directionality in the SMT section exclusion;

65. The solder paste currently on the market has only a sticky time of 4 hours;

66. SMT equipment is generally used at a rated air pressure of 5KG/cm2;

67. SMT parts repair tools are: soldering iron, hot air extractor, suction gun, tweezers;

68. QC is divided into: IQC, IPQC,. FQC, OQC;

69. High-speed placement machines can mount resistors, capacitors, ICs, and transistors;

70. Characteristics of static electricity: small current, greatly affected by humidity;

71. What kind of welding method is used for the front PTH and the reverse SMT through the tin furnace;

72. Common test methods for SMT: visual inspection, X-ray inspection, machine vision inspection

73. The heat transfer mode of ferrochrome repair parts is conducted convection;

74. At present, the main components of BGA materials are tin balls Pb10, SAC305, SAC405;

75. Method for manufacturing steel plate, laser cutting, electroforming, chemical etching;

76. The temperature of the brazing furnace is as follows: the temperature is measured by the temperature measuring device;

77. The welding condition of the SMT semi-finished product of the smelting furnace is that the part is fixed on the PCB;

78. The history of modern quality management development TQC-TQA-TQM;

79. The ICT test is a needle bed test;

80. The ICT test can be used to test electronic parts using static testing;

Today's learning content is here, and the next issue will continue to introduce the common knowledge of SMT, so stay tuned!

  • Tel:0769-81027015
  • Fax:0769-81027025
  • Add:The third, fourth and sixth floors of Building B, Zhonggaocheng Innovation Industrial Park, No. 10 Xinju Road, Shangjiao Village, Chang'an Town, Dongguan City

粤ICP备18111863号 Copyright © 2018 Dongguan Junze Electronic Technology Co., Ltd. All rights reserved
Technical Support:Nanbo

online service

online serviceClose