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Inspection in SMT processing is a very important means to ensure the quality of PCBA. The main inspection methods include manual visual inspection, solder paste thickness gauge inspection, automatic optical inspection, X-ray inspection, online test, flying probe test, etc. Due to the different inspection content and characteristics of each process, the inspection methods used in each process are also different. Among the inspection methods of smt chip processing plants, manual visual inspection, automatic optical inspection and X-ray inspection are the most advanced surface assembly process inspections. There are three commonly used methods. Online testing can be used for both static testing and dynamic testing. The following professional SMT processing manufacturers give you a brief introduction to these detection methods.
1. Manual visual inspection method. This method requires little investment and does not require test program development, but it is slow and subjective, and needs to visually observe the tested area. Due to the lack of visual inspection, it is rarely used as the main welding quality inspection method on the current SMT processing production line, and most of it is used for repair and rework.
2. Optical detection method. With the reduction of PCBA's chip component package size and the increase of circuit board chip density, SMA inspection becomes more and more difficult, and manual visual inspection becomes insufficient, and its stability and reliability are difficult to meet the requirements of production and quality control. Therefore, the use of motion detection is becoming more and more important.
3. Use automatic optical inspection (AO1) as a tool to reduce defects, which can be used to find and eliminate errors in the patch processing process to achieve good process control. AOI adopts an advanced vision system, a new light-giving method, a high magnification and a complex processing method, which can obtain a high defect capture rate at a high test speed.
A successful SMT patch processing production line
Equipped with a fully automatic SMT production line, in addition to the most important placement machine, there are nine important equipment to be matched with the placement machine. Here is a brief introduction:
1. The solder paste mixing machine, the solder paste mixing machine can effectively mix the tin powder and the solder paste evenly. Achieve a more perfect printing and reflow soldering effect, saving manpower and standardizing this operation. Of course, the need to open the can also reduces the chance of absorbing moisture.
2. Oven, used to bake the circuit board when necessary to remove moisture from the circuit board.
3. SMT board loading machine, used for automatic board feeding when the PCB is placed in the Rack (turnover box).
Fourth, the solder paste printer is used to print PCB circuit board solder paste and is equipped in front of the placement machine.
5. SPI solder paste thickness gauge is a device used to measure the thickness, area and volume of the solder paste (red glue) printed on the PCB board after the solder paste printer
6. Reflow soldering furnace. Reflow soldering furnace is the post process of SMT production line. It is used to ablate the solder of already mounted PCB circuit boards and components and bond them with the main board. There are many varieties of reflow ovens, such as hot air reflow oven, nitrogen reflow oven, hot wire reflow oven, hot gas reflow oven, laser reflow oven, etc., which are equipped behind the placement machine
Seven, AOI detector, used after the placement machine, this is called pre-welding inspection, used to detect poor placement of components before soldering, such as offset, reverse, missing parts, reverse white, side standing, etc. of electronic components Poor; it can also be used behind the reflow oven. This is called post-soldering inspection, which detects poor soldering after the reflow oven of electronic components, offset, missing parts, reverse re-inspection and solder joints with more tin, less tin, Defects such as empty welding.
8. The SMT connection station is used to connect the connection equipment of the SMT production equipment center.
Nine, SMT off-board machine is mainly used to accept the circuit board after reflow soldering.
SMT production lines are divided into fully automatic production lines and semi-automatic production lines. If a company wants to construct a complete automatic SMT production line, the placement machine is the most important equipment, and the other nine types of equipment are also indispensable. Companies can also equip other equipment as needed. Such as SMT peripheral equipment (such as: plate turning machine, falling plate machine, parallel transplanting machine, etc.).
