1. Generally speaking, the temperature specified in the SMT workshop is 25±3℃;
2. Materials and tools required for solder paste printing solder paste, steel plate, scraper, wiping paper, dust-free paper, cleaning agent, 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 of the 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 melting tin, and prevent re-oxidation.
6. The volume ratio of tin powder particles and Flux(flux) in the solder paste is about 1:1, and the weight ratio is about 9:1;
7. The principle of using solder paste is first in first out;
8. When the solder paste is used in opening, it must go through two important processes of warming and stirring;
9. The common production methods of steel plates are: etching, laser, electroforming;
10. The full name of SMT is Surface mount(or mounting) technology, which means surface sticking (or mounting) technology in Chinese;
11. The full name of ESD is Electro-static discharge, which means electrostatic discharge in Chinese.
12. When making the SMT equipment program, the program includes five parts, which are 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 is 217C;
14. The controlled relative temperature and humidity of the parts drying box is < 10%;
15. Commonly used Passive Devices include: resistance, capacitor, point sense (or diode), etc.; Active Devices include: transistors, ics, etc.;
16. Commonly used SMT steel material is stainless steel;
17. The thickness of commonly used SMT steel plate is 0.15mm(or 0.12mm);
18. The types of electrostatic charge are friction, separation, induction, electrostatic conduction, etc.; Electrostatic charge on electron worker
The impact of the industry is :ESD failure, electrostatic pollution; The three principles of electrostatic elimination are electrostatic neutralization, grounding, and shielding.
19. Imperial size length x width 0603= 0.06inch*0.03inch, metric size length x width 3216=3.2mm*1.6mm;
20. The 8th code "4" of ERB-05604-J81 represents four circuits with a resistance value of 56 ohms. capacitance
The capacity of ECA-0105Y-M31 is C=106PF=1NF =1X10-6F;
21. ECN Chinese full name: Engineering Change Notice; SWR Chinese full name: Special needs Work Order,
It must be countersigned by all relevant departments and distributed by the document center to be valid;
22. The specific content of 5S is sorting, rectification, cleaning, cleaning, and quality;
23. The purpose of PCB vacuum packaging is to prevent dust and moisture;
24. The quality policy is: comprehensive quality control, implement the system, and provide the quality required by customers; Full participation, timely
Processing, to achieve the goal of zero defects;
25. Quality three No policy: do not accept defective products, do not manufacture defective products, do not outflow defective products;
26. 4M1H of the seven QC techniques for fish bone inspection refers to (Chinese) : people, machines, materials,
Method, environment;
27. The ingredients of the solder paste include: metal powder, solvent, flux, anti-vertical flow agent, active agent; By weight,
Metal powder accounted for 85-92%, and metal powder accounted for 50% by volume; The main components of the metal powder are tin and lead, the ratio is 63/37, and the melting point is 183℃.
28. When the solder paste is used, it must be taken out of the refrigerator to return to the temperature of the frozen solder paste.
Facilitate printing. If the temperature is not restored, the defects that are easy to produce after PCBA Reflow are tin beads;
29. The document supply modes of the machine include: preparation mode, priority exchange mode, exchange mode and quick access mode;
30. SMT PCB positioning methods are: vacuum positioning, mechanical hole positioning, bilateral clamp positioning and plate edge positioning;
31. Silk screen (symbol) indicates the character of a resistance of 272 with a resistance value of 2700Ω and a resistance value of 4.8MΩ
The number (screen printing) is 485;
32. The silk screen on the BGA body contains the manufacturer, manufacturer part number, specifications, Datecode/(Lot No) and other information;
33. The pitch of 208pinQFP is 0.5mm;
34. Among the seven QC techniques, fishbone diagram emphasizes the search for causality;
37. CPK means: the current actual condition of the process capability;
38. The flux begins to volatilize in the constant temperature zone for chemical cleaning;
39. Ideal cooling zone curve and reflux zone curve mirror relationship;
40. RSS curve is temperature rise → constant temperature → reflux → cooling curve;
41. The PCB material we use now is FR-4;
42. PCB warping specification does not exceed 0.7% of its diagonal;
43. STENCIL laser cutting is a method that can be reworked;
44. At present, the BGA ball diameter commonly used on the computer motherboard is 0.76mm;
45. ABS system is absolute coordinates;
46. Ceramic chip capacitor ECA-0105Y-K31 error is ±10%;
47. Panasert Panasonic automatic SMT machine its voltage is 3Ø200±10VAC;
48. SMT parts packaging its coil disc diameter of 13 inches, 7 inches;
49. SMT general steel plate opening is 4um smaller than PCB PAD, which can prevent the phenomenon of poor tin ball;
50. According to PCBA inspection Rules, when the dihedral Angle is > 90 degrees, it means that the solder paste has no adhesion to the wave welding body;
51. When the humidity on the IC display card is greater than 30% after the IC is unpacked, it means that the IC is damp and hygroscopic;
52. The weight ratio and volume ratio of tin powder and flux in the solder paste composition are 90%:10%,50%:50%;
53. The early surface bonding technology originated in the military and avionics fields in the mid-1960s;
54. At present, the most commonly used solder paste Sn and Pb content is: 63Sn+37Pb;
55. The feeding spacing of the paper tape tray with a common bandwidth of 8mm is 4mm;
56. In the early 1970s, the industry introduced a new type of SMD, called "sealed footless chip carrier", often abbreviated as HCC;
57. The resistance of the component with symbol 272 shall be 2.7K ohms;
58. The capacity of 100NF component is the same as that of 0.10uf;
59. The eutectic point of 63Sn+37Pb is 183℃;
60. The largest use of SMT electronic parts material is ceramic;
61. The maximum temperature of the back-welding furnace temperature curve 215C is the most suitable;
62. When inspecting the tin furnace, the temperature of the tin furnace 245C is more appropriate;
63. SMT parts packing its coil type disc diameter 13 inches,7 inches;
64. The open-hole type of steel plate is square, triangle, circle, star shape, this Lei shape;
65. Currently used computer side PCB, its material is: glass fiber board;
66. The solder paste of Sn62Pb36Ag2 is mainly used in the substrate ceramic plate;
67. Rosin based flux can be divided into four kinds: R, RA, RSA, RMA;
68. SMT segment exclusion has no directionality.
69. The solder paste currently on the market has a stickiness time of only 4 hours;
70. The rated air pressure of SMT equipment is 5KG/cm2;
71. What kind of welding method is used when the front PTH and the back SMT pass through the tin furnace?
72. SMT common inspection methods: visual inspection, X-ray inspection, machine vision inspection
73. The heat conduction mode of ferrochrome repair parts is conduction + convection;
74. At present, the main tin ball of BGA material is Sn90 Pb10;
75. Production methods of steel plate laser cutting, electroforming, chemical etching;
76. According to the temperature of the welding furnace: use the temperature gauge to measure the applicable temperature;
77. The SMT semi-finished product of the rotary welding furnace is welded to the PCB when it is exported.
78. The development course of modern quality management TQC-TQA-TQM;
79. The ICT test is a needle bed test;
80. ICT testing can test electronic parts using static testing;
81. The characteristics of solder are that the melting point is lower than other metals, the physical properties meet the welding conditions, and the fluidity is better than other metals at low temperature;
82. The measurement curve should be re-measured to change the process conditions of the welding furnace parts replacement;
83. Siemens 80F/S is a more electronic control drive;
84. Solder paste thickness gauge is the use of Laser light measurement: solder paste degree, solder paste thickness, solder paste printed width;
85. The feeding methods of SMT parts include vibrating feeder, disc feeder and coil feeder;
86. Which mechanisms are used in SMT equipment: CAM mechanism, side rod mechanism, screw mechanism, sliding mechanism;
87. If the inspection section cannot be confirmed, the BOM, manufacturer's confirmation and sample plate shall be performed according to what item;
88. If the part package is 12w8P, the counter Pinth size must be adjusted by 8mm each time;
89. Types of welding machine: hot air welding furnace, nitrogen welding furnace, laser welding furnace, infrared welding furnace;
90. SMT parts sample trial can be used: streamline production, handprint machine mount, handprint hand mount;
91. Commonly used MARK shapes are: circle, "ten" shape, square, diamond, triangle, swastig;
92. SMT segment due to improper Reflow Profile Settings, may cause parts micro-crack is the preheating area, cooling area;
93. Uneven heating at both ends of SMT segment parts is easy to cause: air welding, offset, tombstone;
94. SMT parts maintenance tools are: soldering iron, hot air extractor, suction gun, tweezers;
95. QC is divided into :IQC, IPQC,.FQC, OQC;
96. High speed mounter can mount resistor, capacitor, IC, transistor;
97. Characteristics of static electricity: small current, affected by humidity;
98. The Cycle time of high-speed machine and general-purpose machine should be balanced as far as possible;
99. The true meaning of quality is to do it right the first time;
100. The SMT machine should stick small parts first, and then stick large parts;
101. BIOS is a basic Input/Output System. In English, it is: Base Input/Output System;
102. SMT parts can not be divided into LEAD and LEADLESS two kinds according to the parts foot;
103. The common automatic placement machine has three basic types, continuous placement type, continuous placement type and mass transfer placement machine;
104. SMT can be produced without LOADER in the process;
105. SMT process is board feeding system - solder paste printing machine - high speed machine - universal machine - rotary flow welding - plate receiving machine;
106. When the temperature and humidity sensitive parts are opened, the color displayed in the humidity card circle is blue, and the parts can be used;
107. Size specification 20mm is not the width of the material belt;
108. Reasons for short circuit caused by poor printing in the process:
a. The metal content of the solder paste is not enough, resulting in collapse
b. The opening of the steel plate is too large, resulting in too much tin
c. The steel plate quality is not good, the tin is not good, change the laser cutting template
d. Solder paste remains on the back of Stencil, reduce the pressure of the scraper, and apply appropriate VACCUM and SOLVENT
109. The main engineering purposes of the general backwelding furnace Profile:
a. Preheating zone; Project objective: The capacitive agent volatilization in solder paste.
b. Uniform temperature zone; Project purpose: activation of flux, removal of oxide; Evaporate excess water.
c. Back welding area; Project purpose: solder melting.
d. Cooling zone; Engineering purpose: alloy solder joint formation, part foot and pad joint as a whole;
110. In the SMT process, the main reasons for tin beads are: poor PCB PAD design and poor steel plate opening design
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