SMT surface mount processing involves preparation, printing, surface mount, welding, and inspection and repair processes to ensure accurate installation of electronic components on PCBs. Each process needs to be strictly controlled to ensure product quality and reliability.
1、 Preparation process
Before conducting SMT surface mount processing, sufficient preparation work must be carried out. This includes:
PCB preparation: Select and prepare PCB boards of appropriate size to ensure their surface is clean and flawless, and perform necessary pre-treatment to improve welding quality.
Component preparation: Prepare sufficient electronic components according to production needs. These components need to undergo strict screening to ensure their quality meets the standards.
Preparation of solder paste and patch adhesive: Select suitable solder paste and patch adhesive, which will play a crucial role in the subsequent patch process.
2、 Printing process
The printing process is the first step in SMT surface mount processing, mainly involving the printing of solder paste or surface mount adhesive.
Solder paste printing: Use a screen printing machine to accurately print solder paste onto the solder pads of a PCB. The accuracy of this step is crucial for subsequent processes, as it directly affects the placement and welding quality of the components.
3、 SMT process
The SMT mounting process is the core step of SMT mounting processing, which includes:
Component positioning: Using high-precision SMT machines, electronic components are accurately placed on printed solder paste PCBs. The accuracy and stability of the SMT machine are crucial for ensuring the quality of SMT.
SMT pressure control: During the SMT process, it is necessary to precisely control the pressure exerted by the SMT head on the components to ensure good contact between the components and the PCB.
4、 Welding process
After completing the SMT, the next step is to solder to ensure a secure connection between the components and the PCB.
Reflow soldering: By using a reflow soldering machine, the PCB that has been attached to the component is heated, causing the solder paste to melt and wet the component pins and PCB pads, forming a reliable soldering connection.
Welding quality inspection: After welding is completed, it is necessary to inspect the welding quality to ensure that each welding point meets the quality standards.
5、 Detection and repair process
To ensure the quality of SMT surface mount processing, inspection and repair processes are indispensable.
Automatic Optical Inspection (AOI): Using AOI equipment to automatically inspect the soldered PCB, identify and mark potential welding defects.
X-ray testing: For components with packaging types such as BGA, X-ray testing is also required to ensure the internal welding quality.
Repair process: Once welding defects are found, they need to be repaired in a timely manner. Repairs may include re soldering, replacing components, and other operations to ensure the quality and reliability of the final product.
