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Introduction To Common Knowledge Of SMT
- May 16, 2017 -

1. Generally speaking, the SMT workshop stipulated temperature is 23 ± 7 ℃;
2. Solder paste printing, the necessary materials and tools to prepare: solder paste, steel plate, scraper, wipe paper, dust-free paper, cleaning agent, stirring knife;
3. Commonly used solder paste ingredients are Sn96.5%/Ag3%/Cu0.5%;
4. The main ingredients of solder paste are divided into two parts of tin powder and flux;
5. The main role of flux in welding is to remove oxide, destroy the surface tension of tin, prevent re-oxidation;
6. The paste of tin powder particles and Flux (flux) of the volume ratio of about 1:1, the weight of the ratio of about 9:1;
7. The principle of the extraction of solder paste is advanced first.
8. When used in Kaifeng, the solder paste must undergo two important processes to return temperature and stir.
9. The common production method of steel plate is: etching, laser, electroforming;
10. Smt's full name is Surface mount (or mounting) technology, Chinese meaning for the surface adhesion (or mount) technology;
11. The full name of the ESD is Electro-static discharge, Chinese meaning for electrostatic discharge;
12. The production of SMT equipment, the program includes five parts, this five-part PCB data; Mark data; Feeder data; Nozzle data; part data;
13. Lead-free solder Sn/Ag/Cu 96.5/3.0/0.5 melting point of 217C;
14. Parts Drying Box control relative humidity is the 10%;
15. Commonly used passive components (PassiveDevices) have: resistors, capacitors, inductors (or two polar body), and other active components (ActiveDevices) has: Electro-crystal, IC, etc.
16. Commonly used SMT steel plate material is stainless steel;
17. Commonly used SMT steel plate thickness of 0.15mm (or 0.12mm);
18. Electrostatic charge generated by the types of friction, separation, induction, electrostatic conduction, electrostatic charge of the electronic industry is: ESD failure, electrostatic pollution; three principles of electrostatic elimination for electrostatic neutralization, grounding, shielding;
19. Inch size length x breadth 0603=0.06inch*0.03inch, metric size length × width 3216=3.2mm*1.6mm;
20. The ERB-05604-J81 8th code "4" is expressed as 4 circuits, the resistance is 56 ohm. Capacitance value of ECA-0105Y-M31 is C=106PF=1NF =1X10-6F;
21. ECN Chinese are all known as: Engineering Change notice; SWR in Chinese all known as: Special Needs work orders, must be countersigned by the relevant departments, document center distribution, the party is effective;
22. The specific content of 5S for sorting, rectification, cleaning, cleanliness, literacy;
23. PCB Vacuum Packaging is the purpose of dustproof and moisture-proof;
24. Quality Policy is: comprehensive quality control, implementation system, provide customer demand of the qualities, full participation, timely processing, to achieve the goal of 0 shortcomings;
25. Quality Three policy is: do not accept bad products, do not make bad products, do not flow out of bad products;
26. Seven QC methods refer to the checklist, layer method, Plato, Causality diagram, scatter graph, histogram, control graph;
27. The ingredients of solder paste include: Metal powder, dissolving-relief, flux, anti-dip flow agent, active agent; by weight, metal powder accounted for 85-92, by volume of metal powder accounted for 50%;
28. Solder paste must be used in the refrigerator to remove the back temperature, the purpose is: to let the refrigerated solder paste temperature back to room temperature, to facilitate printing. If the temperature is not back in the PCBA after the Reflow easy to produce the bad for tin bead;
29. The file supply mode of the machine is: Preparation mode, preferential Exchange Mode, switching mode and quick mode;
30. SMT PCB positioning methods are: vacuum positioning, mechanical hole positioning, bilateral clamp positioning and plate edge positioning;
31. Silk screen (symbol) for 272 resistors, resistance to 2700 ω, the resistance of 4.8M ω symbol (silk screen) for 485;
32. Silk screen on BGA ontology contains information such as manufacturer, manufacturer's material number, specification and Datecode/(Lot No.);
33.208pinQFP pitch is 0.5mm;
34. Seven major methods of QC, the Fishbone chart emphasizes the search for causation;
35. CPK refers to the process capacity in the current situation;
36. Flux in the thermostatic area began to volatile chemical cleaning action;
37. Ideal cooling zone curve and reflux region curve mirroring relationship;
38. Sn62Pb36Ag2 solder paste is mainly used in ceramic plate;
39. Rosin-based flux can be divided into four kinds: R, RA, RSA, RMA;
40. RSS curves are warming → constant temperature → reflux → cooling curve;
41. We are using the PCB material for FR-4;
42. PCB Warp Specifications not exceeding 0.7% of its diagonal;
43. STENCIL production of laser cutting is a re-work method;
44. The current computer motherboard commonly used BGA ball diameter is 0.76mm;
45. ABS system is absolute coordinates;
46. Ceramic chip capacitance ECA-0105Y-K31 error is ± 10%;
47. The current use of the computer's PCB, its material is: Fiberglass board;
48. SMT parts packaging the coil with a diameter of 13 inch, 7 inches;
49. SMT General steel plate openings than the PCB pad small 4um can prevent the undesirable phenomenon of tin balls;
50. According to the PCBA inspection specification when the dihedral angle > 90 degrees, the solder paste and the wave welding body without adhesion;
51. The humidity display card after the IC unpacking is more than 30% in the case of the IC damp and moisture absorption;
52. The weight ratio and volume ratio of tin powder to flux in solder paste is 90%:10%,50%:50%;
53. Early surface adhesion technology originated in the field of military and aviation electronics in in the mid 1960 of the 20th century;
54. Currently the most commonly used SMT solder paste SN and PB content are: 63Sn 37Pb; eutectic point is 183 ℃;
55. The common bandwidth of 8mm paper tape tray feeding spacing is 4mm;
56. In the early in the 1970 of the 20th century, a new SMD appeared in the industry, which was "sealed without foot-chip carrier", often with LCC Jane.
57. The symbol of the 272 component of the resistance should be 2.7K ohm;
58. The capacitance value of the 100NF component is identical to 0.10uf;
60. The material of the electronic components with the largest use of SMT is ceramics;
61. The peak temperature curve of the return welding furnace is the most suitable for 215C.
62. Tin furnace inspection, tin furnace temperature 245 ℃ more appropriate;
63. Steel plate Openings type square, triangle, circular, star-shaped, this lei-shaped;
64. SMT segment resistance has no directivity;
65. The current market on the sale of solder paste, actually only 4 hours of sticky time;
66. The general use of SMT equipment rated pressure for 5KG/cm2;
67. SMT Parts Maintenance tools are: soldering iron, hot air selector, suction tin gun, tweezers;
68. QC is divided into: IQC, IPQC,. FQC, OQC;
69. High speed SMT machine can be mounted resistors, capacitors, IC, transistors; packaging method for Reel, Tray Two, Tube is not suitable for high speed SMT machine;
70. Electrostatic characteristics: Small current, affected by humidity;
71. Positive PTH, reverse SMT tin furnace use of the welding method of double wave welding;
72. Common inspection methods of SMT: visual inspection, x-ray inspection, machine vision inspection;
73. Chromium Iron Repair Parts heat conduction mode for conduction convection;
74. At present, the main ingredient of the tin balls of BGA material Sn90 Pb10,SAC305,SAC405;
75. The production method of steel plate laser cutting, electroforming method, chemical etching;
76. The temperature of the welding furnace is according to: the applicable temperature is measured by temperature measurement;
77. The welding condition of the SMT semi-finished products in the welding furnace is fixed on the PCB.
78. The course of modern quality management development TQC-TQA-TQM;
79. ICT testing is a needle-bed test;
80. ICT testing can be measured by static testing of electronic components;
81. Solder property is melting point than other metals low, physical performance meets welding conditions, low temperature liquidity than other metals;
82. Changing the process condition of the parts replacement of the welding furnace to measure the measuring curve;
83. Siemens 80F/S belongs to more electronic control transmission.
84. Solder paste Thickness gauge is the use of laser light measurement: solder paste, solder paste thickness, solder paste the width of the printing;
85. The feeding method of SMT parts has vibrating feeder, disc feeder, coil feeder;
86. Which institutions are used in SMT equipment: cam mechanism, side bar mechanism, screw mechanism, sliding mechanism;
87. If the inspection section cannot be confirmed, then the work BOM, vendor confirmation, sample plate;
88. If the part packing method is 12w8P, the counter Pinth size must be adjusted each time into 8mm;
89. Type of welding machine: hot-blast furnace, nitrogen welding furnace, laser welding furnace, infrared ray welding furnace;