smt知识（SMT knowledge）.doc

smt知识（SMT knowledge） Generally speaking, 1. The temperature of the SMT workshop rules of 25 + / - 3 ℃; 2. When the paste is printed, the materials and tools needed to prepare the paste, steel plate, scraper, wipe paper, dust free paper, cleaning agent and stirring knife; 3. The commonly used alloy composition is Sn/Pb alloy, and the proportion of alloy is 63/37. 4. The main components of solder paste are divided into two parts, tin powder and flux. The main function of the flux in welding is to remove oxides, damage the surface tension and prevent reoxidation. 6. The ratio of tin powder in tin paste to Flux (Flux) is approximately 1:1, and the ratio of weight is about 9:1. 7. The use principle of solder paste is advanced first. 8. When the paste is used in kaifeng, two important processes shall be passed to warm and stir. 9. Common production methods of steel plates are: etching, laser, electroforming; 10. Is the full name of SMT Surface mount technology (or mounting), the Chinese meaning for the Surface adhesion (or SMT) technology; 11. The full name of ESD is electro-static discharge, which means electrostatic discharge in Chinese. 12. When making SMT equipment, the program includes five parts, the five parts are PCB data; Mark the data; Feeder data; Nozzle data; Part data. 13. Unleaded solder Sn/Ag/Cu 96.5/3.0/0.5 melting point is 217C; The relative temperature humidity of the parts drying box is 10%; 15. Passive Devices (Passive Devices) include: resistance, capacitance, point sense (or diodes); Active Devices include: transistors, IC, etc. 16. Commonly used SMT plates are made of stainless steel; 17. The thickness of commonly used SMT steel plates is 0.15mm (or 0.12mm); 18. The types of electrostatic charge generation such as friction, separation, sensor, static electricity conduction; electrostatic charge for electronic industry, electrostatic pollution; for: the influence of ESD failure three principle of electrostatic elimination of electrostatic neutraliza