Global Soul Limited Company News

In the process of welding in an aerobic environment, secondary oxidation will occur, resulting in poor wetting, especially in the miniaturization and close spacing process, which will lead to more deadly hazards: voids, which easily lead to a decrease in the strength of the solder joints of micro-components; Tin ball, easy to lead to short circuit between closely spaced components; Virtual welding affects the electrical performance and service life of the product. HB reflow low oxygen concentration control technology is specifically designed for expensive components, double-sided assembly, micro-spaced components, small volume components, high temperature solders, and production processes that require high reliability for welding. The results show that in nitrogen environment, the surface tension of liquid solder decreases and the wetting Angle increases by 40%. Increase wetting capacity by 3-5%; Wetting time can be reduced by 15%; Effectively reduce peak temperature and shorten reflux time. In the SELEIT reflow nitrogen system, the oxygen concentration can be independently controlled throughout the whole process, which effectively solves the above problems.

110 essential knowledge of SMT 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

Alarm item software processing method Alarm cause alarm exclusion System power failure The system automatically enters the cooling state and automatically sends the PCB in the furnace to the external power failure Internal circuit fault Repair external circuit Overhaul internal circuitry If the hot air motor does not rotate, the system automatically enters the cooling state The hot air motor is damaged or stuck. Check the inverter Replace or repair the motor If the transmission motor does not rotate, the system automatically enters the cooling state Motor is not stuck or damaged check frequency conversion Replace or repair the motor The board drop system automatically enters the cooling state. The PCB falls or gets stuck Electrical eye damage at transport inlet and outlet The external object mistakenly senses the entrance electric eye and sends the board out to replace the electric eye If the lid is not closed, the system automatically enters the cooling state The lifting screw travel switch is shifted to close the upper furnace and restart Readjust the position of the travel switch When the temperature exceeds the upper limit, the system automatically enters the cooling state Solid state relay output short circuit The computer and PLC cable are unplugged Check whether the temperature control template works properly. Replace the hot spot couple Replace solid state relay Plug in the strip Check the temperature control template If the temperature is lower than the minimum temperature, the system automatically enters the cooling state. The output end of the solid-state relay is disconnected Ground the thermocouple The leakage switch of the generator tube is switched off to replace the solid state relay Adjust the thermocouple position Repair or replace the heating pipe When the temperature exceeds the alarm value, the system automatically enters the cooling state The output end of the solid state relay is normally closed The computer and PLC cable are unplugged Check whether the temperature control template works properly. Replace the thermocouple Replace solid state relay Plug in the strip Check the temperature control template The system automatically enters the cooling state when the temperature is lower than the alarm value. The output end of the solid-state relay is disconnected Ground the thermocouple The leakage switch of the generator tube is switched off to replace the solid state relay Check the temperature control template The system automatically enters the cooling state when the temperature is lower than the alarm value. The output end of the solid-state relay is disconnected Ground the thermocouple The leakage switch of the generator tube is switched off to replace the solid state relay Adjust the thermocouple position Repair or replace the heating pipe The transport motor speed deviation is large. The system automatically enters the cooling state. The transport motor is faulty Encoder fault Inverter failure Replace the motor Fix and replace encoder Change frequency converter The start button is not reset The system is in the waiting state. The emergency switch is not reset The start button is not pressed Start button damaged Line damage reset emergency switch and press start button Replacement button Fix the circuit Press the emergency switch The system is in the waiting state. Press the emergency switch Reset the emergency switch and press the start button to check the external circuit High temperature 1. The hot air motor is faulty 2. The wind turbine is faulty 3. Solid state relay output short circuit 4. Check the wind wheel 5. Replace the solid state relay working process The machine cannot start. 1. The upper furnace body is not closed 2. The emergency switch is not reset 3. The start button is not pressed 4. Check the emergency switch 5. Press the Start button to start the process The temperature in the heating zone does not rise to the set temperature 1. The heater is damaged 2. The power-on couple is faulty 3. The output end of the solid state relay is disconnected 4. The exhaust is too large or the left and right exhaust is unbalanced 5. The photoelectric isolation device on the control board is damaged The transport motor is abnormal. The transport thermal relay detects that the motor is overloaded or stuck 1. Restart the transport thermal relay 2. Check or replace the thermal relay 3. Reset the thermal relay current measurement value Inaccurate count 1. The sensing distance of the counting sensor is changed 2. The counting sensor is damaged 3. Adjust the sensing distance of the technical sensor 4. Replace the counting sensor The error of the speed value on the computer screen is large 1. The speed feedback sensor senses the wrong distance 2. Check whether the encoder is faulty 3. Check the encoder circuit

In the SMT entire line process, after the SMT machine completes the mounting process, the next step is the welding process, reflow welding process is the most important process in the entire SMT surface mounting technology. Common welding equipment includes wave welding, reflow welding and other equipment, and the role of reflow welding four temperature zones, respectively, are preheating zone, constant temperature zone, back welding zone and cooling zone. Each of the four temperature zones has its own significance. SMT reflow preheating area The first step of reflow welding is preheating, which is to activate the solder paste, avoid the preheating behavior caused by poor welding caused by rapid high temperature heating during tin immersion, and evenly heat the normal temperature PCB board to achieve the target temperature. In the heating process to control the heating rate, too fast will produce thermal shock, may cause damage to the circuit board and components; Too slow, the solvent volatilization is insufficient, affecting the welding quality. SMT reflow insulation area The second stage - insulation stage, the main purpose is to make the temperature of the PCB board and the components in the reflow furnace stable, so that the temperature of the components is consistent. Because the size of the components is different, the large components need more heat, the temperature is slow, the small components are heated up fast, and enough time is given in the insulation area to make the temperature of the larger components catch up with the smaller components, so that the flux is fully volatilized to avoid bubbles when welding. At the end of the insulation section, the oxides on the pad, solder ball and component pins are removed under the action of flux, and the temperature of the entire circuit board is also balanced. All components should have the same temperature at the end of this section, otherwise there will be various bad welding phenomena in the reflux section due to the uneven temperature of each part. Reflow back weld area The temperature of the heater in the reflow area rises to the highest, and the temperature of the component rises rapidly to the highest temperature. In the reflux street section, the peak welding temperature varies with the welding paste used, the peak temperature is generally 210-230 ° C, and the reflux time should not be too long to prevent adverse effects on the components and PCB, which may cause the circuit board to be scorched. Reflow cooling zone In the final stage, the temperature is cooled below the freezing point temperature of the solder paste to solidify the solder joint. The faster the cooling rate, the better the welding result. If the cooling rate is too slow, it will lead to the generation of excessive eutectic metal compounds, and the large grain structure is easy to occur at the welding point, so that the strength of the welding point is low, and the cooling rate of the cooling zone is generally about 4℃/S, cooling to 75℃.

The tip of the wave crest solder joint is that the solder on the wave crest solder joint is in the shape of milky stone or water column when the circuit board is welded by the wave crest, and this form is said to be the tip. Its essence is that the solder is generated by gravity greater than the internal stress of the solder, and the reasons for this are analyzed as follows: (1) Poor flux or too little: this reason will cause the soldering solder to be wet on the surface of the solder spot, and the solder on the surface of the copper foil is very poor, at this time, it will produce a large area of the PCB board. (2) The transmission Angle is too low: the PCB transmission Angle is too low, the soldering solder is easy to accumulate on the surface of the solder joint in the case of relatively poor fluidity, and the condensation process of the solder is eventually due to the gravity is greater than the internal stress of the solder, forming a pull tip. (3) Solder crest velocity: the scouring force of the solder crest on the solder joint is too low, and the fluidity of the solder is in a poor state, especially lead-free tin, the solder joint will adsorb a large number of solder joints, which is easy to cause too much solder and produce a pull tip. (4) PCB transmission speed is not suitable: the setting of wave soldering transmission speed must meet the requirements of the welding process, if the speed is suitable for the welding process, the formation of the tip can be unrelated to this. (5) Too deep tin immersion: too deep tin immersion will cause the soldering solder joint to be completely coked before leaving, because the surface temperature of the PCB board is too high, the PCB solder will accumulate a large amount of solder on the solder joint due to the diffusability change, forming a pull tip. The solder depth should be appropriately reduced or the welding Angle increased. (6) Wave welding preheating temperature or tin temperature deviation is too large: too low temperature will make the PCB into the solder, the solder surface temperature drops too much, resulting in poor fluidity, a large number of solder will accumulate on the solder surface to produce a pull tip, and too high temperature will make the flux coking, so that the wettability and diffusion of the solder become worse, may form a pull tip.

The first day of SMT equipment precautions; What should device users and managers do on their first day back at work after a holiday? First of all, the plant disinfection, industrial safety inspection, fire inspection and other start inspections. Then please pay attention to the following: (1) Turn on the air conditioning of the plant in advance, and the temperature and humidity meet the requirements. (2) Open the workshop air source switch to confirm that the air pressure meets the requirements. (3) Confirm that the main power supply of the workshop equipment is turned off. (4) Confirm that the main power supply voltage of the workshop or production line meets the requirements, and turn on the switch. (5) Turn on the power of the device one by one. After the device is fully turned on, turn on the next device one by one. (6) After the equipment power supply is turned on, the origin is returned and the test mode heat engine is run. (7) Please follow the above procedures. If you have any questions, please contact the equipment manufacturer's after-sales phone or wechat. In order to reduce the post-holiday startup failure rate, SMT shares the following SMT equipment needs to pay attention to several matters First confirm whether the temperature and humidity of the SMT workshop exceed the environmental requirements, whether the equipment is damp, whether there is dew, do not rush to rise the temperature of the SMT workshop in a cold environment, the equipment is easy to produce dew. (At this time, it is forbidden to turn on the power supply) The specific practice refers to the SMT workshop environment of each factory according to the different degrees of moisture to the equipment for dehumidification treatment time selection, (industrial control electrical part to check whether it is normal) open the front and rear chassis covers of the equipment (pay attention not to touch the wire inside the corner), and place the fan in the front 0.5 meters of the chassis for blowing operations (purpose: Note: Do not use hot air), according to the degree of moisture to choose 2-6 hours of blowing operation, after the moisture removal operation, turn on the power, check that it is correct, but do not return to the origin, about 30-60 minutes after the boot in the back to the origin of preheating 1 Printing machine Solder paste printer Solder paste printing machine precautions 1, remove the scraper to clean the residual solder paste 2, after cleaning the screw guide rail, add special new lubricating oil 3, use the air gun to clean the dust of electrical parts 4, use the anti-seat cover protection phase 5, rail transport belt check whether it is replaced 6, whether the cleaning mechanism needs to be cleaned 7, the cylinder holding steel mesh mechanism is normal 8, check whether the gas path is normal 9, electrical industrial control Whether it is normal 2. Patch machine Points to note for the placement machine First check whether the electrical part of the industrial control is normal, check whether there is no product falling off the track belt is damaged and deformed screw rod clean the dust and inject the special new lubricating oil nozzle air path is normal Feeder guide chute cleaning and maintenance Automatic change nozzle device clean and electrostatic inspection and maintenance Discharge box cleaning in addition to static inspection and maintenance of universal machine backpack mechanism Cleaning inspection and maintenance of Feeder automatic refueling vehicle mechanism inspection and maintenance 3 Reflow welding reflow welding precautions 1, reflow welding machine annual maintenance 2, clean the residual components in the furnace, rosin; Transport chain cleaning and maintenance after adding high temperature chain oil, fine mesh belt inspection and maintenance. 3. Clean the hot air motor with an air gun. Dust on the heating wire, clean up the reflow electric box part, mainly the internal dust of the electric box, must add drying agent to avoid the electrical equipment being affected by 4, completely cut off the power supply of the equipment, be sure to confirm that the ∪PS power supply is off 5, confirm whether the fan is running normally 6, preheating area, constant temperature area, reflux area, Cooling zone four temperature zone system is normal 7, cooling zone flux recovery system inspection and maintenance 8, water inspection is normal 9, furnace seal device is normal 10, import and export cutting curtain inspection and maintenance 11, empty plate on the track to check whether the track deformation card phenomenon 1, completely clean up the welding residue of the spray device, blow off the welding aid, add alcohol, use the spray mode, clean up the welding aid pipe, nozzle, after cleaning, empty the alcohol to ensure that the machine is free of flux, alcohol inflammables 3, use the air gun to clean the hot air motor, heat wire dust, use the gun to clean the electric box part, mainly the internal dust of the electrical appliance. If necessary, add drying agent to avoid electrical appliances by the south 4, completely cut off the power supply of the equipment 5, industrial control electrical part is normal 6, track inspection and maintenance   5AOIAOI Precautions: 1, guide screw cleaning and maintenance add new butter 2, use air gun to remove part of the electrical dust, add desiccant in the electric box 3, clean and protect with dust cover 4, check whether the light source mechanism is normal 5, check whether the equipment movement shaft and motor are normal   6 Peripheral equipment loading and unloading machine business 1, screw column fill butter 2, use air gun to clean the electrical part of the dust, add desiccant in the electric box 3, the material frame down to the bottom of the shelf, clean the sensor dust. 1, drive shaft, pulley cleaning, refueling 2, cleaning and cleaning sensor equipment users and managers after the first day of work need to do? On the first day back at work after a holiday, the core things that equipment users and managers need to do include adjusting their schedules, reviewing work plans, conducting safety checks and communicating with colleagues. ‌ Firstly, ‌ adjusting work schedule ‌ is an important preparation for the first day back at work after the holiday. Device users and managers need to go to bed early and get up early, get enough sleep and avoid staying up late in order to feel energized for the new day ‌. Secondly, ‌ reviewing the work plan and objectives ‌ is also a necessary step. On the first day of work, take the time to review your work plan and goals, identify what you want to do in the New Year, and how to achieve the expected results. This helps to stay focused and increase productivity ‌. Equipment user 1. Appearance inspection: Check whether the equipment has physical damage, such as scratches, cracks or corrosion. 2. Cleaning and maintenance: Remove dust, water, oil and other impurities from the equipment to keep the equipment clean. 3. Functional test: Carry out basic functional test on the equipment to ensure that all components can work normally. 4. Make the maintenance plan of the machine and equipment, and ensure the timely implementation, prevent equipment failure, improve production efficiency ‌. 1. Safety device: Check whether the safety protection device of the equipment is in good condition, such as safety door, emergency stop button, etc. 2. Electrical inspection: Ensure the safety of electrical connections, gas path inspection, waterway inspection, no exposed wires or damaged plugs and other matters. 3. Check whether the factory production fire protection and ventilation are normal, and check the workshop environment and production supporting facilities. 1. Calibration equipment: For precision equipment, such as test equipment, calibration is carried out to ensure that the measurement results are accurate. 2. Process parameters: Check and adjust the process parameters of the equipment to meet the production requirements. 1. Lubrication maintenance: lubricate the parts that need to be lubricated to ensure smooth operation of the equipment. 2. Production material preparation: Prepare the materials required for production and ensure adequate supply. 3. Production consumables preparation: Prepare the consumables required for production to ensure adequate supply. 1. Power operation: Observe the power status of the equipment before the formal no-load. 2. No-load operation: Before the formal production, carry out no-load operation test to observe the operating status of the equipment. 3. Trial production: small batch trial production, check the production capacity and product quality of the equipment. Record and report: 1. Record inspection: record the results of equipment inspection and testing, including any problems found and measures taken. 2. Information synchronization: Synchronize the device status and problems to the superior or related departments. Equipment manager 1. Personnel management held a meeting of equipment users, emphasized equipment operation safety and precautions, and reminded employees to return to work as soon as possible. Understand the physical and mental state of employees to avoid fatigue and other situations. 2, make plans according to the production plan, reasonable arrangement of equipment use and maintenance plan. Develop a response plan in case of emergency. 3, safety inspection organization professional personnel to carry out a comprehensive safety inspection of the equipment. Pay special attention to the inspection of special equipment (such as pressure vessels, elevators, etc.) to ensure compliance with relevant regulations. 4, the overall inspection of the equipment to check the maintenance records of the equipment to see if there are remaining problems to be dealt with. Inspection of all equipment, in addition to the content of the user inspection, but also pay attention to the overall operating environment of the equipment, such as whether the channel around the equipment is smooth, whether the fire equipment is in place. For key equipment and special equipment, it is necessary to focus on checking its safety and reliability, and arrange professional personnel to test if necessary. 5, work arrangement according to the production plan and equipment status, reasonable arrangement of equipment use tasks, to avoid equipment overuse or idle. Ensure adequate supply of raw materials, accessories, tools, etc. required for equipment. Finally, ‌ and communicating with colleagues ‌ is also the key to a smooth start to the new journey. Sharing the mood and experience of the holiday and talking about the expectations for the next efforts can help relieve the tense working atmosphere, enhance the feelings among colleagues, and lay a good foundation for team cooperation ‌

The lack of solder in the crest solder joint means that the solder joint is shriveled, the solder joint is incomplete with holes (blow holes, pinholes), the solder is not full in the cartridge holes and through holes, or the solder does not climb to the plate of the component surface. Wave solder shortage phenomenon Wave solder shortage phenomenon 1, PCB preheating and welding temperature is too high, so that the viscosity of the molten solder is too low. Preventive measures: the preheating temperature is 90-130 ℃, and the upper limit of preheating temperature is taken when there are more mounted components; Solder wave temperature is 250±5℃, welding time is 3~5s; 2, the aperture of the insertion hole is too large, and the solder flows out of the hole. Preventive measures: The aperture of the insertion hole is 0.15~0.4mm straight than the pin (the lower limit is taken for the thin lead, the upper limit is taken for the thick lead); 3, insert the component fine lead large pad, the solder is pulled to the pad, so that the solder joint is shriveled. Preventive measures: the size of the pad and the diameter of the pin should match, which should be conducive to the formation of the meniscus solder joint. 4. Poor quality of metallized holes or flux resistance flowing into holes. Preventive measures: reflect to the printed board processing plant, improve the processing quality; 5, the crest height is not enough. Cannot make the printed board produce pressure on the solder wave, which is not conducive to tinning. Preventive measures: the peak height is generally controlled at 2/3 of the thickness of the printed board; 6, the printed board climbing Angle is small, is not conducive to flux exhaust. The climbing Angle of the printed board is 3-7°.

1. The first is the quality of the steel mesh: the thickness of the steel mesh and the opening size determine the printing quality of the solder paste. Too much solder paste will produce bridging, too little solder paste will produce insufficient solder paste or virtual welding. The opening shape of the steel mesh and whether the opening wall is smooth also affect the release quality. 2, followed by solder paste quality: solder paste viscosity, printing rolling, service life at room temperature will affect the printing quality. 3. Printing process parameters: there is a certain restrictive relationship between the speed of the scraper, the pressure, the Angle of the scraper and the plate and the viscosity of the solder paste. Therefore, only by correctly controlling these parameters can we ensure the printing quality of solder paste. 4. Equipment accuracy: When printing high-density and narrow spacing products, the printing accuracy and repeat printing accuracy of the printing press will also have a certain impact. 5. Ambient temperature, humidity, and environmental hygiene: too high ambient temperature will reduce the viscosity of the solder paste, when the humidity is too high, the solder paste will absorb moisture in the air, the humidity will accelerate the evaporation of the solvent in the solder paste, and the dust in the environment will cause the solder joint to produce pinholes and other defects. It can be seen from the above introduction that there are many factors affecting the quality of printing, and the printing solder paste is a dynamic process. Therefore, the establishment of a complete set of printing process control documents is very necessary, the selection of the correct solder paste, steel mesh, combined with the most suitable printing machine parameter setting, can make the entire printing process more stable, controllable, standardized.

Reflow welding is divided into main defects, secondary defects and surface defects. Any defect that disables the function of SMA is called a major defect; Secondary defects refer to the wettability between solder joints is good, does not cause the loss of SMA function, but has the effect of product life may be defects; Surface defects are those that do not affect the function and life of the product. It is affected by many parameters, such as solder paste, paste accuracy and welding process. In our SMT process research and production, we know that reasonable surface assembly technology plays a vital role in controlling and improving the quality of SMT products. I. Tin beads in reflow soldering 1. Mechanism of tin bead formation in reflow welding: The tin bead (or solder ball) that appears in reflow welding is often hidden between the side or the fine-spaced pins between the two ends of the rectangular chip element. In the component bonding process, the solder paste is placed between the pin of the chip component and the pad. As the printed board passes through the reflow furnace, the solder paste melts into a liquid. If the liquid solder particles are not well wetted with the pad and the device pin, etc., the liquid solder particles cannot be aggregated into a solder joint. Part of the liquid solder will flow out of the weld and form tin beads. Therefore, the poor wettability of the solder with the pad and the device pin is the root cause of the formation of tin beads. Solder paste in the printing process, due to the offset between the stencil and the pad, if the offset is too large, it will cause the solder paste to flow outside the pad, and it is easy to appear tin beads after heating. The pressure of the Z axis in the mounting process is an important reason for tin beads, which is often not paid attention to. Some attaching machines are positioned according to the thickness of the component because the Z axis head is located according to the thickness of the component, which will cause the component to be attached to the PCB and the tin bud will be extruded to the outside of the welding disc. In this case, the size of the tin bead produced is slightly larger, and the production of the tin bead can usually be prevented by simply re-adjusting the Z-axis height. 2. Cause analysis and control method: There are many reasons for poor solder wettability, the following main analysis and related process related causes and solutions: (1) improper reflux temperature curve setting. The reflux of the solder paste is related to temperature and time, and if sufficient temperature or time is not reached, the solder paste will not reflux. The temperature in the preheating zone rises too fast and the time is too short, so that the water and solvent inside the solder paste are not completely volatilized, and when they reach the reflow temperature zone, the water and solvent boil out the tin beads. Practice has proved that it is ideal to control the temperature rise rate in the preheating zone at 1 ~ 4℃/S. (2) If tin beads always appear in the same position, it is necessary to check the metal template design structure. The corrosion accuracy of the template opening size can not meet the requirements, the size of the pad is too large, and the surface material is soft (such as copper template), which will cause the external outline of the printed solder paste to be unclear and connected to each other, which mostly occurs in the pad printing of fine-pitch devices, and will inevitably cause a large number of tin beads between the pins after reflow. Therefore, suitable template materials and template making process should be selected according to the different shapes and center distances of pad graphics to ensure the printing quality of solder paste. (3) If the time from the patch to reflow soldering is too long, the oxidation of the solder particles in the solder paste will cause the solder paste to not reflow and produce tin beads. Choosing a solder paste with a longer working life (generally at least 4H) will mitigate this effect. (4) In addition, the solder paste misprinted printed board is not sufficiently cleaned, which will cause the solder paste to remain on the surface of the printed board and through the air. Deform the printed solder paste when attaching components before reflow soldering. These are also the causes of tin beads. Therefore, it should accelerate the responsibility of operators and technicians in the production process, strictly comply with the process requirements and operating procedures for production, and strengthen the quality control of the process. two One end of the chip element is welded to the pad, and the other end is tilted up. This phenomenon is called the Manhattan phenomenon. The main reason for this phenomenon is that the two ends of the component are not heated evenly, and the solder paste is melted successively. Uneven heating at both ends of the component will be caused in the following circumstances: (1) The component arrangement direction is not designed correctly. We imagine that there is a reflow limit line across the width of the reflow furnace, which will melt as soon as the solder paste passes through it. One end of the chip rectangular element passes through the reflow limit line first, and the solder paste melts first, and the metal surface of the end of the chip element has liquid surface tension. The other end does not reach the liquid phase temperature of 183 ° C, the solder paste is not melted, and only the bonding force of the flux is far less than the surface tension of the reflow solder paste, so that the end of the unmelted element is upright. Therefore, both ends of the component should be kept to enter the reflow limit line at the same time, so that the solder paste on the two ends of the pad is melted at the same time, forming a balanced liquid surface tension, and keeping the position of the component unchanged. (2) Insufficient preheating of printed circuit components during gas phase welding. The gas phase is the use of inert liquid vapor condensation on the component pin and PCB pad, release heat and melt the solder paste. The gas phase welding is divided into the balance zone and the steam zone, and the welding temperature in the saturated steam zone is as high as 217 ° C. In the production process, we found that if the welding component is not sufficiently preheated, and the temperature change above 100 ° C, the gasification force of the gas phase welding is easy to float the chip component of the package size of less than 1206, resulting in the vertical sheet phenomenon. By preheating the welded component in a high and low temperature box at 145 ~ 150℃ for about 1 ~ 2min, and finally slowly entering the saturated steam area for welding, the phenomenon of sheet standing was eliminated. (3) The impact of pad design quality. If a pair of pad size of the chip element is different or asymmetrical, it will also cause the amount of printed solder paste is inconsistent, the small pad responds quickly to the temperature, and the solder paste on it is easy to melt, the large pad is the opposite, so when the solder paste on the small pad is melted, the component is straightened under the action of the surface tension of the solder paste. The width or gap of the pad is too large, and the sheet standing phenomenon may also occur. The design of pad in strict accordance with the standard specification is the prerequisite to solve the defect. Three. Bridging Bridging is also one of the common defects in SMT production, which can cause short circuits between components and must be repaired when the bridge is encountered. (1) The solder paste quality problem is that the metal content in the solder paste is high, especially after the printing time is too long, the metal content is easy to increase; The viscosity of the solder paste is low, and it flows out of the pad after preheating. Poor slump of solder paste, after preheating to the outside of the pad, will lead to IC pin bridge. (2) The printing system printing press has poor repeat accuracy, uneven alignment, and solder paste printing to copper platinum, which is mostly seen in fine-pitch QFP production; The steel plate alignment is not good and PCB alignment is not good and the steel plate window size/thickness design is not uniform with the PCB pad design alloy coating, resulting in a large amount of solder paste, which will cause bonding. The solution is to adjust the printing press and improve the PCB pad coating layer. (3) The sticking pressure is too large, and the soaking of the solder paste after pressure is a common reason in production, and the Z-axis height should be adjusted. If the accuracy of the patch is not enough, the component is shifted and the IC pin is deformed, it should be improved for the reason. (4) The preheating speed is too fast, and the solvent in the solder paste is too late to volatilize. The core-pulling phenomenon, also known as the core-pulling phenomenon, is one of the common welding defects, which is more common in vapor phase reflow welding. The core suction phenomenon is that the solder is separated from the pad along the pin and the chip body, which will form a serious virtual welding phenomenon. The reason is usually considered to be the large thermal conductivity of the original pin, the rapid temperature rise, so that the solder is preferred to wet the pin, the wetting force between the solder and the pin is much greater than the wetting force between the solder and the pad, and the upwarping of the pin will aggravate the occurrence of the core suction phenomenon. In infrared reflow welding, PCB substrate and solder in the organic flux is an excellent infrared absorption medium, and the pin can partially reflect infrared, in contrast, the solder is preferentially melted, its wetting force with the pad is greater than the wetting between it and the pin, so the solder will rise along the pin, the probability of core suction phenomenon is much smaller. The solution is: in the vapor phase reflow welding, the SMA should be fully preheated first and then put into the vapor phase furnace; The weldability of PCB pad should be carefully checked and guaranteed, and PCB with poor weldability should not be applied and produced; The coplanarity of components cannot be ignored, and devices with poor coplanarity should not be used in production. Five. After welding, there will be light green bubbles around the individual solder joints, and in serious cases, there will be a bubble the size of a nail, which not only affects the appearance quality, but also affects the performance in serious cases, which is one of the problems that often occur in the welding process. The root cause of the welding resistance film foaming is the presence of gas/water vapor between the welding resistance film and the positive substrate. Trace amounts of gas/water vapor are carried to different processes, and when high temperatures are encountered, gas expansion leads to the delamination of the solder resistance film and the positive substrate. During welding, the temperature of the pad is relatively high, so the bubbles first appear around the pad. Now the processing process often needs to be cleaned, dry and then do the next process, such as after etching, should be dried and then stick the solder resistance film, at this time if the drying temperature is not enough will carry water vapor into the next process. The PCB storage environment is not good before processing, the humidity is too high, and the welding is not dried in time; In the wave soldering process, often use a water-containing flux resistance, if the PCB preheating temperature is not enough, the water vapor in the flux will enter the inside of the PCB substrate along the hole wall of the through hole, and the water vapor around the pad will first enter, and these situations will produce bubbles after encountering high welding temperature. The solution is: (1) all aspects should be strictly controlled, the purchased PCB should be inspected after storage, usually under standard circumstances, there should be no bubble phenomenon. (2) PCB should be stored in a ventilated and dry environment, the storage period is not more than 6 months; (3) PCB should be pre-baked in the oven before welding 105℃/4H ~ 6H;

Patch adhesive is a pure consumption of non-essential process products, now with the continuous improvement of PCA design and technology, through hole reflow, double-side reflow welding has been realized, the use of patch adhesive PCA mounting process is becoming less and less. SMT adhesive, also known as SMT adhesive, SMT red adhesive, is usually a red (also yellow or white) paste evenly distributed with hardener, pigment, solvent and other adhesives, mainly used to fix components on the printed board, generally distributed by dispensing or steel screen printing methods. After affixing the components, place them in the oven or reflow furnace for heating and hardening. The difference between it and the solder paste is that it is cured after heat, its freezing point temperature is 150 ° C, and it will not dissolve after reheating, that is to say, the heat hardening process of the patch is irreversible. The use effect of SMT adhesive will vary due to the thermal curing conditions, the connected object, the equipment used, and the operating environment. The adhesive should be selected according to the printed circuit board assembly (PCBA, PCA) process. Features, applications and prospects of SMT adhesive: SMT red glue is a kind of polymer compound, the main components are the base material (that is, the main high molecular material), filler, curing agent, other additives and so on. SMT red glue has viscosity fluidity, temperature characteristics, wetting characteristics and so on. According to this characteristic of red glue, in the production, the purpose of using red glue is to make the parts firmly stick to the surface of the PCB to prevent it from falling. Therefore, the patch adhesive is a pure consumption of non-essential process products, and now with the continuous improvement of PCA design and process, through hole reflow and double-sided reflow welding have been realized, and the PCA mounting process using the patch adhesive is showing a trend of less and less. SMT adhesive is classified according to the mode of use: Scraping type: The sizing is carried out through the printing and scraping mode of steel mesh. This method is the most widely used and can be used directly on the solder paste press. The steel mesh holes should be determined according to the type of parts, the performance of the substrate, the thickness and the size and shape of the holes. Its advantages are high speed, high efficiency and low cost. Dispensing type: The glue is applied on the printed circuit board by dispensing equipment. Special dispensing equipment is required, and the cost is high. Dispensing equipment is the use of compressed air, the red glue through the special dispensing head to the substrate, the size of the glue point, how much, by the time, pressure tube diameter and other parameters to control, dispensing machine has a flexible function. For different parts, we can use different dispensing heads, set parameters to change, you can also change the shape and quantity of the glue point, in order to achieve the effect, the advantages are convenient, flexible and stable. The disadvantage is easy to have wire drawing and bubbles. We can adjust the operating parameters, speed, time, air pressure, and temperature to minimize these shortcomings. SMT patch adhesive typical curing conditions: 100℃ for 5 minutes 120 ° C for 150 seconds 150℃ for 60 seconds 1, the higher the curing temperature and the longer the curing time, the stronger the bonding strength. 2, because the temperature of the patch adhesive will change with the size of the substrate parts and the mounting position, we recommend to find the most suitable hardening conditions. The thrust strength requirement of the 0603 capacitor is 1.0KG, the resistance is 1.5KG, the thrust strength of the 0805 capacitor is 1.5KG, the resistance is 2.0KG, which can not reach the above thrust, indicating that the strength is not enough. Generally caused by the following reasons: 1, the amount of glue is not enough. 2, the colloid is not 100% cured. 3, PCB board or components are contaminated. 4, the colloid itself is brittle, no strength. Thixotropic instability A 30ml syringe glue needs to be hit tens of thousands of times by air pressure to be used up, so the patch glue itself is required to have excellent thixotropy, otherwise it will cause instability of the glue point, too little glue, which will lead to insufficient strength, causing the components to fall off during wave soldering, on the contrary, the amount of glue is too much, especially for small components, easy to stick to the pad, preventing electrical connections. Insufficient glue or leak point Reasons and Countermeasures: 1, the printing board is not cleaned regularly, should be cleaned with ethanol every 8 hours. 2, the colloid has impurities. 3, the opening of the mesh board is unreasonable too small or the dispensing pressure is too small, the design of insufficient glue. 4, there are bubbles in the colloid. 5. If the dispensing head is blocked, the dispensing nozzle should be cleaned immediately. 6, the preheating temperature of the dispensing head is not enough, the temperature of the dispensing head should be set at 38℃. The causes of over-wave soldering are very complex: 1. The adhesive force of the patch is not enough. 2. It has been impacted before wave soldering. 3. There is more residue on some components. 4, the colloid is not resistant to high temperature impact

"Point-and-shoot" operation of the first SMT tester The SMT electronics factory buys the first detection machine to improve the detection efficiency of the first piece and create more profits for the enterprise. Therefore, the sooner the equipment is purchased and put into the production line, the better, and whether the first detection machine can be put into the production line depends on whether the operator has mastered the use of it. SMT first tester brand Operating the first detector only requires the operator to know basic computer operations. That is, the switch of the computer, the mouse keyboard operation, the basic operation of Excle, so the operation of the first machine is very simple, and the operator can master the entire detection process under the guidance of the engineer in only 1 to 3 working days. If you have any questions in the course of subsequent use, you can also contact the engineers of Global Soul Limited for timely remote or on-site resolution. Quality products and quality service are the philosophy of Global Soul Limited.

1. Virtual welding It is a common welding defect that some IC pins appear in virtual welding after welding. Reason: pin coplanarity is poor (especially QFP, due to improper storage, resulting in pin deformation); Poor solderability of pins and pads (long storage time, yellow pins); During welding, the preheating temperature is too high and the heating speed is too fast (easy to cause IC pin oxidation). 2, cold welding It refers to the solder joint formed by incomplete reflux. Reason: insufficient heating during welding, insufficient temperature. 3. Bridge One of the common defects in SMT, which causes a short circuit between components and must be repaired when the bridge is encountered. Reason: solder paste collapse; Too much solder paste; The pressure is too large during the patch; Reflux heating speed is too fast, the solvent in the solder paste too late to volatilize. 4. Erect a monument One end of the chip component is lifted and stands on its other end pin, also known as the Manhattan phenomenon or suspension bridge. Reason: The fundamental is caused by the imbalance of the wetting force at both ends of the component. Specifically related to the following factors: (1) The design and layout of the pad is unreasonable (if one of the two pads is too large, it will easily cause uneven heat capacity and uneven wetting force, resulting in unbalanced surface tension of the molten solder applied to the two ends, and one end of the chip element may be completely wet before the other end begins to wet). (2) The printing amount of the solder paste in the two pads is not uniform, and the more end will increase the heat absorption of the solder paste and lag the melting time, which will also lead to the imbalance of the wetting force. (3) When the patch is installed, the force is not uniform, which will cause the component to be immersed in the solder paste at different depths, and the melting time is different, resulting in uneven wetting force on both sides; Patch time shift. (4) When welding, the heating speed is too fast and uneven, making the temperature difference everywhere on the PCB large.   5, wick suction (wick phenomenon) Resulting in a virtual weld, or bridge if the pin spacing is fine, is when the molten solder wets the component pin, and the solder climbs up the pin from the solder spot position. It mostly occurs in PLCC,QFP,SOP. Reason: When welding, due to the small heat capacity of the pin, its temperature is often higher than the temperature of the solder pad on the PCB, so the first pin wetting; The solder pad is poor in weldability, and the solder will climb. 6. Popcorn phenomenon Now most of the components are plastic sealed, resin encapsulated devices, they are particularly easy to absorb moisture, so their storage, storage is very strict. Once the moisture is absorbed, and it is not completely dried before use, at the time of reflux, the temperature rises sharply, and the internal water vapor expands to form the popcorn phenomenon. 7. Tin beads It affects the appearance and also causes bridging. There are two types: one side of a chip element, usually a separate ball; Around the IC pin, there are scattered small balls. Reasons: the flux in the solder paste is too much, the solvent volatilization is not complete in the preheating stage, and the solvent volatilization in the welding stage causes splashing, resulting in the solder paste rushing out of the solder pad to form tin beads; The thickness of the template and the size of the opening are too large, resulting in too much solder paste, causing the solder paste to overflow to the outside of the solder plate; When printing, the template and the pad are offset, and the offset is too large, which will cause the solder paste to overflow to the pad. When mounting, the Z-axis pressure causes the component to be attached to the PCB, and the solder paste will be extruded to the outside of the pad. When reflux, the preheating time end and heating rate are fast. 8. Bubbles and pores When the solder joint is cooled, the volatile matter of the solvent in the internal flux is not completely dispatched. It is related to temperature curve and flux content in solder paste. 9, solder joint tin shortage Reason: printing template window is small; Low metal content of solder paste. 10, solder joints too much tin Cause: The template window is large. 11, PCB distortion Reason: PCB itself material selection is improper; PCB design is not reasonable, component distribution is not uniform, resulting in PCB thermal stress is too large; Double-sided PCB, if one side of the copper foil is large, and the other side is small, it will cause inconsistent shrinkage and deformation on both sides; The temperature in reflow welding is too high. 12. Cracking phenomenon There is a crack in the solder joint. Reason: After the solder paste is taken out, it is not used up within the specified time, local oxidation, forming a granular block, which is difficult to melt during welding and cannot be fused with other solders into one piece, so there is a crack on the surface of the solder joint after welding. 13. Component offset Cause: The surface tension of the molten solder at both ends of the chip element is unbalanced; The conveyor vibrates during transmission. 14, the solder joint dull luster Cause: The welding temperature is too high, the welding time is too long, so that the IMC is transformed into. 15, PCB solder resistance film foaming After welding, there are light green bubbles around the individual solder joints, and in serious cases, there will be thumbnail-sized bubbles, affecting the appearance and performance. Reason: There is gas/water vapor between the solder resistance film and the PCB substrate, which is not completely dried before use, and the gas expands when welding at high temperature. 16, PCB solder resistance film color changes Solder resistance film from green to light yellow, cause: the temperature is too high. 17, PCB multi-layer board layering Cause: Plate temperature is too high.