1、表面组装技术复习题（Review of surface mount technology）Chapter 1: Introduction1. what is the surface mount technology (SMT): without inserting hole on the printed circuit board drill, directly to the surface mount micro components welded to a printed circuit board or other substrate surface provides advanced
2、electronic position assembly technology.2. what is the surface mount technology (THT): the surface mount component mounted to the borehole PCB, after reflow soldering or to form a reliable mechanical and electrical connection between the circuit components and surface mounted PCB plate.What advantag
3、es does Smt 3. have compared with tht?4., SMT technology system covers: mechanical, electronic, optical, material, chemical, computer, network, automatic control.5. from a technical point of view: SMT technology is a component, printed board, SMT design and assembly process, equipment, materials and
4、 inspection techniques, such as composite technology.The 6. substrate is a structural component interconnected by components, and plays an important role in ensuring the electrical performance and reliability of the electronic assembly.7., the core technology of information industry, chip manufactur
5、ing industry, has entered our country and laid a solid foundation for the sustainable development of SMT technology in china.8. countries in the world in order to prevent SMT technology gap between the expansion of decision-making: to strengthen scientific research and basic research.8., in the deve
6、lopment of SMT, the surface assembly technology has been developed toward high density, fine, high flexibility, high reliability and variety.9. electronic components electronic information equipment cell plate circuit assembly technology is the basis for manufacturing electronic equipment. The emerg
7、ence of different types of electronic components always leads to a revolution in the technology of board level circuit assembly.10., SMT involves not only electronic equipment and equipment manufacturing, but also components manufacturing, PCB manufacturing, materials manufacturing and manufacturing
8、 process equipment manufacturing, but ultimately services for electronic manufacturing.11. assembly process and equipment are the tools and means to implement SMT products, which determine the production efficiency and quality results.12. early surface assembly technology in China originated from th
9、e military and Avionics field in 1980s.13. the United States is the first country in the world where SMD and SMT originated.14., Japan introduced SMD and SMT from the United States in 1970s, and Japans development in patch SMT soon surpassed the United States and was in the leading position in the w
10、orld.15, Europes SMT started late, and its level of development and SMC/SMD efficiency in the whole machine after Japan and the United states.16., according to PHILPS forecast: by 2010, the use of plug-in components worldwide will be from the current 40% to 1O%, and conversely, SMC/SMD will rise fro
11、m 60% to about 90%.17., because the SMC SMD reduces the effect of lead distribution characteristics, and on the surface of PCB welding firm, greatly reducing the parasitic capacitance and parasitic inductance between the leads, thus largely reduce the electromagnetic interference and radio frequency
12、 interference, improve frequency characteristic.The 18. and second generation BGA packages are face down, and flip chip technology is widely used in BGA and CSP19., SMT development trends, the development of electronic components and surface assembly technology development direction?The development
13、of electronic components: the emergence of different types of electronic components will always lead to a revolution in the technology of board level circuit assembly.The development trend of SMT technology is to develop in the direction of high density, fine, high flexibility, high reliability and
14、variety.20. what are the definitions and advantages of flip chip technology?Definition: flip chip directly through the chip is convex array interconnection between the chip and the circuit board, the chip upside down on the circuit board, and placed opposite direction of conventional chip package, s
15、o that the flip chip Flip Chip.Advantages: flip chip offers many advantages, including reduced component size, improved performance, and reduced cost.21., how is the development of surface assembly technology in our country at this stage?(1) tht will circuit assembly, pin through hole reflow technol
16、ogy is applied in hybrid assembly.(2) the second generation SMT will dominate the board circuit assembly.(3) to the further development of the third generation of SMT surface mount technology, the third circuit assembly revolution climax, promote the electronics industry into a new era.22., BGA pack
17、aging development process.(1) first generation BGA plastic type down facing type.(2) the downward facing type of the second generation BGA belt type. It adopts lead frame and plastic module package(3) the third generation is also a new generation of BGA. The final assembly process (i.e., WLP), which
18、 uses the crystal as the carrier for transmission, replaces the previous bonding technologies used (wire bonding, TAB and flip chip bonding).23. integrated passive components in the following forms of packaging:(1) array: many of the same type of passive components are integrated together and sealed
19、 in the form of face array terminalsInstall.(2) network: many hybrid resistors and capacitors are integrated and encapsulated in the form of peripheral terminals.(3) mixing: some passive components and active devices are mixed and integrated for encapsulation.(4) embedding: embedding passive compone
20、nts into PCB or other substrates.(5) integrated mixing: the integrated passive components are encapsulated in QFP or TSOP format.Main points of knowledge -1.SOP package features: small integrated circuit, both sides of the pin is J type bending.2.FC package features: down facing solder type flip chi
21、p integrated circuit.3.QFP package features: four pin flat, J type bending.4.SOJ package: IC integrated circuit pin aduncous on both sides.5.PLCC package: four pin bend, plastic cable chip.6.DIP outline package: dual in line form integrated circuit.7.SOIC outline package: small integrated IC circuit
22、.8. triode shape of two kinds of packaging: (1) SOT23 form of packaging.(2) D form encapsulation.9.CERQUAD shape package: four sides lead to ceramic carrier, short lead, ground package tube shell.10.CLCC package: ceramic chip carrier with a pin, and the CLCC letter C shape, four pin bends.11.SMC sha
23、pe package: long pin plug-in chip electronic components.12.SMD outline package: no pin SMD electronic components.13.PFP shape package: the appearance is rectangular, four sides have “gull wing“ shaped pin.14.SMC and _SMD are the basis of SMT.15., PBGA, TBGA, FBGA, CSP and FC are the current trends i
24、n IC packaging development.The development direction of 16. chip components of SMC: since 1990s, chip components further miniaturization and multi-layered, high-capacity, high voltage and high performance development direction.In the 17. components commonly used numerical methods are marked _ direct
25、 scale method, _ color method and standard method _ number three.The quality of 18. SMT applications depends more than 50% on the mastery and development capabilities of SMC and SMD.19. crystal triode with current amplification role, SMT transistors are common SOT and D form of packaging.20.SMT surf
26、ace assembly technology, SMD components are mainly ceramic and plastic packaging two types.21. ceramic capacitor application range: suitable for high frequency circuits.The 22. QFP has a 208 foot pitch of 0.5mm. 0805 capacitor size is english.23. roll packing method, used currently on the market are
27、 the main adhesive packing beltThe component value of 24. symbol 272 should be 2.7K ohms.25., for example, the capacitance of the 100NF capacitor is the same as the capacitance value of the 0.10uf capacitor.26. common SMT parts, foot shape: R, foot shapedThe volume and weight of 27. SMD is only abou
28、t 1/10 of traditional plug-in components.28. metric size 3.2mm * 1.6mm in English, code 1206.29. marked as 472uF, the capacity of aluminum electrolytic capacitor is 4700uF.30. IC sockets, connectors and switches are primarily tht packages and are now available in the SMT package.31. common polarity
29、of the two capacitors are electrolytic capacitors and tantalum capacitors.33., how to determine the polarity direction of IC?:Usually the No.1 IC pin will be marked with a small side gap or white,General IC on the back of the lower left corner of the screen is the direction for the first leg of IC.T
30、he increase of the amount of the 34. chip component brings the bottleneck problem to the mount process What is the effective way to solve this problem?Bottleneck: the production line is out of balance, the equipment utilization is reduced, the cost is raised, and the chip supply time is 30% of the p
31、roduction line time, which seriously affects the production.The effective way to solve the bottleneck problem of the SMT process is to realize the integration of passive components.35. what are the conditions for surface mount SMC and SMD components?The conditions for surface mounting are as follows
32、:1) the shape of the component is suitable for automated surface mount;2) the size and shape are interchangeable after standardization;3) have good dimensional accuracy;4) suitable for flow or non pipelining;5) have a certain mechanical strength;6) able to withstand the washing of organic solutions
33、(alcohol);7) sporadic packaging and tape packing can be carried out;8) interchangeability of electrical and mechanical properties;9) the resistance to welding heat stress conforms to the corresponding regulations.36., a resistor size of 3.2mm, and its width is 1.6mm, for this resistance of the Briti
34、sh size code?Solution: by 1 inches, =25.4mm,Can calculate the length and width of the imperial size.There are as follows:Length: 3.2 inches, 25.4=0.1259Width: 1.6 inches, 25.4=0.0629So the English code is 1206Answer: the English code for this resistor is 1206.37., a resistor size of 1.0mm, and its w
35、idth is 0.5mm, for this resistance of the British size code?Solution: by 1 inches, =25.4mm,Can calculate the length and width of the imperial size.There are as follows:Length: 1 inches, 25.4=0.04 =40milWidth: 0.5 inches, 25.4=0.02 =20milSo the English code is 0402.Answer: the English code for this r
36、esistor is 0402.38, there are 1000 solder joints on a circuit board, and the number of circuit boards is 500. The total number of defects detected is 20, and the defect rate is DPM.Solution: according to the defect rate of millions of parts, the statistical formula is as follows.Defect rate DPM= tot
37、al number of defects * 106/ total solder jointsTotal solder joint = check board number * solder jointTotal number of defects = check the total number of defects on the circuit boardFormula can be worked out:The defect rate is DPM=20 * 106/ (1000 * 500) =40DPMAnswer: the defect rate is 40DPM.39., a r
38、esistance length of 1.6mm, and its width is 0.8mm, for this resistance of the British size code:Solution: by 1 inches, =25.4mm,Can calculate the length and width of the imperial size.There are as follows:Length: 1.6 inches, 25.4=0.0629Width: 0.8 inches, 25.4=0.0314So the English code is 0603Answer:
39、the English code for this resistor is 06031. commonly used solder alloy composition for _ tin and lead alloy, and the ratio of _63:37 63Sn+37Pb alloy; eutectic point: 183 degrees centigrade.2. solder paste: Tin + flux + diluent. There are four kinds of flux based on rosin:R, RA, RSA, RMA3., the so-c
40、alled 2125 material is: L=2.0, W=1.25.4. solder paste is a chemically active substance, so its environmental requirements are very strict. Generally, the temperature is 210 degrees and the humidity is between 20% and 21%. The period of validity is 6 months.5., the use of solder paste must follow the
41、 “first in first out“ principle, do not cause solder paste in cold storageInter compartment.6. surface mount technology SMT basic requirements for SMT?Answer: no impurities and bubbles in the package, long storage period, non-toxic.Glue point shape and volume are same, glue point section is high, wi
42、thout drawing wire.The color is easy to identify, easy to manual and automatic machine, check the quality of glue points.High initial adhesive force. The flow characteristics of the gum affect the formation of the gum point and its shape and sizeHigh speed curing. The curing temperature of the glue
43、is low and the curing time is short. Heat curing, glue will not collapse.The high strength and elasticity, can withstand soldering temperature.The solidification has good electric properties, has the characteristics of good repair.The clearance of rubber pad, by high PCB solder layer height and thic
44、kness of the metal component and end to determine the difference.6. surface mount technology SMT basic requirements for SMT?Answer: no impurities and bubbles in the package, long storage period, non-toxic.Glue point shape and volume are same, glue point section is high, without drawing wire.The colo
45、r is easy to identify, easy to manual and automatic machine, check the quality of glue points.High initial adhesive force. The flow characteristics of the gum affect the formation of the gum point and its shape and sizeHigh speed curing. The curing temperature of the glue is low and the curing time
46、is short. Heat curing, glue will not collapse.The high strength and elasticity, can withstand soldering temperature.The solidification has good electric properties, has the characteristics of good repair.The clearance of rubber pad, by high PCB solder layer height and thickness of the metal componen
47、t and end to determine the difference.I. The main features of SMB:1. high densityWith the SMC lead spacing from 1.27mm to 0.762mm, 0.635mm to 0.508mm, 0.1mm to 0.381mm, 0.305mm until the transition,The development of SMB to level five wiring density, namely: 1.27 mm in the center distance between th
48、e pads allow the three wiring, at the center of the 2.54mm through the four line wiring allows pad spacing between the (line width and spacing of 0.1 mm), and also to the five wiring in the direction of development. ?2. small apertureIn SMT, because most of the metal holes on the SMB no longer used
49、for insertion of components, but to realize the connection through each layer of the circuit, SMB metal through hole diameter to 0.6? 0.3mm? 0.1mm direction.3. multilayer numberSMB is not only suitable for single and double sided plates, but also has been widely used in multilayer boards with high-density wiring. In modern large-scale electronic computers, multilayer SMB is very common, and the highest number of layers can reach nearly 100 layers. ?4. thick high aperture ratioThe thickness and aperture ratio of PCB is generally below 3, while SMB is more than 5, even up to 21. This a
