Group line mode of SMT production system
Generally ,we understand literally the electronic processing production line is composed of the surface coating equipment, the surface mount assembly equipment, the welding machine, the cleaning machine, the test equipment and other surface assembly equipment. The SMT production system is customarily called the SMT production line.
At present, the variety and specification of the surface-assembly components are not completed, so some through-hole (THT) components are sometimes required in surface assembly (SMA). Therefore, the surface assembly components generally referred to both a plug-in and a mount component, and only a part fully used of SMC/SMD . Both the plug-in and the mount components are assembled is a hybrid assembly, all assembled with SMC/SMD become surface assembly.
According to the different assembly object, assembly craft and assembly method, the SMT production line has multiple group lines mode.
The SMT production line of reflow soldering technology is generally used for surface assembly occasion of single-sided PCB assembly SMC/SMD, also known as single-wire form. If the SMC/SMD is assembled on both sides of the PCB, a production line in the form of two-wire assembly line is required. When both the plug-in and the mount components are combined, sometimes it is necessary to attach the insert assembly line and the corresponding equipment to the original production line. When the non-clean-free assembly is used , additional post-weld cleaning equipment is required. At present, some large enterprises have set up an integrated assembly system for SMT products equipped with a feeding trolley and controlled and managed by a computer. It is a high-level organization form for automatic assembly and production of SMT products.
The following is the general craft process of the SMT production line, in which the presence or absence of the solder paste coating method, the soldering method and the dispensing process are different depending on the method of the group line.
1. Printing: Solder paste or SMD adhesive is printed on the welding pads of the PCB to prepare for soldering of components. All equipment is a solder paste printer located at the forefront of the SMT line.
2. Dispensing: it is to drop the glue to the fixed position of the PCB, its main functionis to fix the components to the PCB when using wave soldering. The equipment used is a dispenser, located at the most forefront of the SMT line or behind the inspection equipment.
3.Mounting and assembly: the surface assembly components are accurately mounted to the fixed position of the PCB. The equipment used is a mounting machine located behind the solder paste printer in the SMT line.
4.Patch adhesive curing: When using the SMD adhesive, the patch glue is cured, so that the surface assembly components and the PCB are firmly bonded together. The equipment used is a curing oven located behind the mounting machine in the SMT line.
5.Reflow soldering: the solder paste is melted, so that the surface assembly components and the PCB are firmly bonded together. The equipment used was a reflow oven. Located behind the mounting machine in the SMT line.
6.Clear: Remove the solder residue that is harmful to the human body or the product on the assembled PCB, such as flux. The equipment used is a cleaning agent, place can not be fixed, may be online or not. This process is not set when using no-clean welding technology.
7.Inspection: Inspection of the welding quality and assembly quality of the assembled SMA (surface assembly components). The equipment used includes magnifying glass, microscope, online tester (ICT), first piece detector, flying needle tester, automatic optical detector (AOI), X-RAY detector, functional tester, etc. The position can be configured in a suitable place on the production line according to the needs of testing.
8.Rework: Rework the SMA that detected the fault. The tools used are electric irons, rework stations, etc. Configure in anywhere in the production line.
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