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1. Generally speaking, the temperature specified in SMT workshop is 25 3℃;
2. Materials and tools needed for solder paste printing: solder paste, steel plate, scraper, wiping paper, dust-free paper, cleaning agent and 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 solder paste are divided into two parts: tin powder and flux.
5. The main function of flux in welding is to remove oxides, destroy the surface tension of molten tin and prevent reoxidation.
6. The volume ratio of tin powder particles to flux in solder paste is about 1: 1, and the weight ratio is about 9: 1.
7. The use principle of solder paste is FIFO;
8. When solder paste is used in Kaifeng, it must go through two important processes: heating and stirring.
9. The common manufacturing methods of steel plates are: etching, laser and electroforming;
The full name of 10. SMT is surface mounting (or mounting) technology, which means surface mounting technology in Chinese.
The full name of 1 1.ESD is Electro-static discharge, which means electrostatic discharge in Chinese.
12. When making SMT equipment program, the program includes five parts, namely PCB data; ; Tag data; Feeder data; Nozzle data; Part data;
13. the melting point of lead-free solder Sn/Ag/Cu 96.5/3.0/0.5 is 2 17℃.
14. The control relative temperature and humidity of the parts drying box are as follows
15. Commonly used passive devices are: resistor, capacitor, inductor (or diode), etc. Active devices include transistors and integrated circuits.
16. Commonly used SMT steel plates are made of stainless steel;
17. The thickness of common SMT steel plates is 0.15mm (or 0.12mm); );
18. The types of electrostatic charges include friction, separation, induction and electrostatic conduction. The effects of electrostatic charge on electronic industry are: ESD failure, electrostatic pollution; The three principles of electrostatic elimination are electrostatic neutralization, grounding and shielding.
19. English dimension length x width 0603 = 0.06 inch * 0.03 inch, metric dimension length x width 32 16 = 3.2 mm * 1.6 mm;
20. The exclusion ERB-05604-J8 1 code 8 "4" is represented by four circuits with a resistance of 56 ohms. The capacitance ECA-0 105Y-M3 1 is c =106pf =1nf =1x10-6f;
2 1.ECN Chinese full name: engineering change notice; SWR is called "special work order" in Chinese, and it is only valid if it is countersigned by relevant departments and distributed by the document center;
The specific content of 22.5S is sorting, rectifying, sweeping, cleaning and literacy;
23. The purpose of PCB vacuum packaging is to prevent dust and moisture;
24. The quality policy is: total quality control, implementation of the system, and provision of quality required by customers; Full participation, timely treatment, in order to achieve the goal of zero defects;
25. Three-no-quality policy is: do not accept defective products, do not manufacture defective products, and do not circulate defective products;
26. Among the seven methods of QC, 4M 1H respectively refers to (Chinese): people, machines, materials, methods and environment;
27. The components of solder paste include: metal powder, solvent, flux, anti-sag agent and active agent; The weight percentage of the metal powder is 85-92% and the volume percentage is 50%; The main components of metal powder are tin and lead, the ratio is 63/37, and the melting point is 183℃.
28. When using solder paste, it must be taken out of the refrigerator and heated. The purpose is to restore the temperature of the refrigerated solder paste to normal temperature for printing. If the temperature does not rise, the defect that PCBA is easy to appear after reflow soldering is tin beads;
29. The file supply modes of the machine include: preparation mode, priority exchange mode, exchange mode and quick access mode;
30. PCB positioning methods of SMT include: vacuum positioning, mechanical hole positioning, double-sided fixture positioning and board edge positioning;
3 1. The symbol (screen printing) of the resistor with screen printing (symbol) of 272, resistance value of 2700Ω and resistance value of 4.8MΩ is 485;
32. Screen printing on BGA body contains information such as manufacturer, manufacturer's material number, specification and date code/(batch number);
33.208pinQFP spacing is 0.5mm;;
34. Among the seven skills of QC, fishbone diagram emphasizes finding causality;
35.CPK refers to the process capability under the current actual situation;
36. The flux starts to volatilize in the constant temperature zone for chemical cleaning;
37. The mirror image relationship between the ideal cooling zone curve and the reflux zone curve;
40. The RSS curve is heating → constant temperature → reflux → cooling curve;
4 1. The PCB material we are using now is FR-4;
42. The warpage specification of the printed circuit board shall not exceed 0.7% of its diagonal;
43. The template laser cutting is a method that can be reworked;
44. At present, the ball diameter of BGA commonly used on computer motherboards is 0.76mm;;
45.ABS system is in absolute coordinates;
46. The error of ceramic chip capacitance ECA-0 105Y-K3 1 is10%;
47. Panaset Panasonic automatic mounter voltage is 3&; Oslash200 10v AC;
48. The diameter of the winding reel for SMT parts packaging is 13 inch, 7 inch;
49. Usually, the opening of SMT steel plate is 4um smaller than the opening of PCB pad, which can prevent the solder ball from being defective.
50. According to PCBA inspection standard, when dihedral angle is greater than 90 degrees, it means that there is no adhesion between solder paste and wave solder.
5 1. When the humidity on the humidity display card is greater than 30% after the IC is unpacked, it means that the IC is damp and absorbs moisture;
52. The correct weight ratio and volume ratio of tin powder to flux in solder paste composition are 90%: 10% and 50%: 50% respectively;
53. Early surface mount technology originated in 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 feeding interval of 55.8 mm ordinary paper tape tray is 4 mm;
56. In the early 1970s1970s, a new SMD, a "sealed footless chip carrier", was often replaced by HCC.
57. The resistance of the component with symbol 272 should be 2.7K ohms;
58. The capacity of100nf module is the same as that of 0. 10uf;
The * * crystallizing point of 59.63Sn+37Pb is183℃;
60. The electronic components with the largest use of SMT are made of ceramics;
The maximum temperature of 6 1. reflow oven curve is 265438 05℃.
62. When checking the tin furnace, the temperature of the tin furnace is 245℃.
63. The diameter of take-up reel for SMT parts packaging is 13 inch, 7 inch;
64. The opening types of steel plates are square, triangle, circle, star and embedded;
65. At present, the materials of computer PCB are: glass fiber board;
66. what kind of substrate is sn 62 Pb 36 ag 2 solder paste mainly used for: ceramic board;
67. Fluxes based on rosin can be divided into four types: R, RA, RSA and RMA;;
68. Does SMT segment exclusion have directionality: None;
69. At present, the actual viscosity time of solder paste on the market is only 4 hours;
70.SMT equipment generally adopts the rated air pressure of 5 kg/cm2;
7 1. PTH on the front and what welding method is used when SMT on the back passes through the tin furnace: double wave welding of spoiler;
72. Common detection methods of SMT: visual detection, X-ray detection and machine vision detection.
73. The heat conduction mode of ferrochrome restoration is: conduction+convection;
74. At present, the solder balls of BGA materials are mainly Sn 90 Pb10;
75. Manufacturing methods of steel plates: laser cutting, electroforming and chemical etching;
76. The temperature of the reflow oven is as follows: Measure the applicable temperature with a thermometer.
77. When the SMT semi-finished products of the reflow oven are exported, the welding condition is that the parts are fixed on the PCB;
78. The development of modern quality management: TQC-TQA-TQM:
79.ICT test is a needle bed test;
80.ICT testable electronic components are tested statically;
8 1. Solder is characterized by its lower melting point than other metals, its physical properties meet the welding conditions, and its fluidity is better than other metals at low temperature.
82. When the reflow oven parts replacement process conditions change, the temperature curve should be re-measured.
83. Siemens 80F/S belongs to electronic control drive;
84. Solder paste thickness gauge uses laser to measure: solder paste degree, solder paste thickness and solder paste printing width;
85.SMT parts are supplied by vibrating feeder, disc feeder and belt feeder.
86. Which mechanisms are used in SMT equipment: cam mechanism, side bar mechanism, screw mechanism and sliding mechanism;
87. If the visual inspection part cannot be confirmed, which operation should be followed: BOM, manufacturer's confirmation, sample.
88. If the packaging method of parts is 12w8P, the interval of counters will be adjusted by 8 mm at a time;
89. reflow oven type: hot air reflow oven, nitrogen reflow oven, laser reflow oven and infrared reflow oven;
90. The methods that can be used for trial production of SMT parts are: assembly line production, installation of handprint machine and handprint installation;
9 1. Commonly used mark shapes are: circle, cross, square, diamond, triangle and swastika;
92. Due to the improper setting of reflow curve of SMT part, the preheating zone and cooling zone may cause the parts to crack. 93. Uneven heating at both ends of SMT parts is easy to cause: virtual welding, deviation and tombstone;
94.SMT parts repairman has: soldering iron, hot air extractor, tin suction gun and tweezers;
95.QC is divided into: IQC, IPQC,. OQC FQC; ;
96. The high-speed mounter can mount resistors, capacitors, integrated circuits and transistors.
97. The characteristics of static electricity: small current, greatly influenced by humidity;
98. The cycle time of high-speed machine and general machine should be as balanced as possible;
99. The essence of quality is to do it well the first time;
100. The mounter should attach small parts first, and then large parts;
10 1.BIOS is the basic input and output system, and the whole English is the base input/output system;
102. SMT parts can be divided into leaded parts and leaded parts according to the presence or absence of parts feet.
103. There are three basic types of common automatic mounters: continuous mounters, continuous mounters and mass transfer mounters.
104.SMT can be produced without loader;
105.SMT process board feeding system-solder paste printing machine-high speed machine-universal machine-reflow soldering-receiver;
106. When the temperature and humidity sensitive component is turned on, the color displayed in the circle of the humidity card is blue, and the component can be used;
107. The size specification of 20mm is not the width of the material belt;
108. Causes of short circuit caused by poor printing in the process:
A. The metal content of solder paste is not enough, leading to collapse; B. The opening of the steel plate is too large, resulting in too much tin;
C, the steel plate is poor in quality and tin plating, and the laser cutting template is replaced; D. There is residual solder paste on the back of the template. In order to reduce the pressure of the scraper, appropriate vacuum and Solevent are adopted.
109. Main engineering purposes of side area of general reflow oven:
A. preheating zone; Engineering application: Solvent volatilization in solder paste. B. uniform temperature zone; Engineering purposes: flux activation and oxide removal; Evaporate excess water. C. recirculation zone; Engineering application: solder melting. D. cooling zone; Engineering application: forming alloy solder joints and connecting the pins and pads of parts into a whole.
In 1 10. In SMT process, the main causes of solder balls are: poor design of PCB pads, poor design of steel plate openings, excessive depth or pressure of mounting parts, excessive rising slope of contour curves, solder paste collapse and low viscosity of solder paste.
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