Welcome to Guangzhou Tongsen Electronic Technology Co., LTD. Website!
What are the precautions for SMT production?
First, there is the solder paste printer, which must be equipped with an optical positioning system; otherwise, the welding quality will be greatly affected. Second, the FPC is fixed to the tray, but there will always be some small gaps between the FPC and the tray. This is a major difference from the PCB substrate.
1. Traditional SMD Mounting
Features: Few surface mount components, low requirements for surface mount processing accuracy, components mainly resistors and capacitors;
SMT Process Flow:
1. Solder Paste Printing: Printing uses a small semi-automatic printing machine, or manual printing, but the quality of manual printing is inferior to automatic printing.
2. Chip Mounting in SMT Processing: Generally, manual chip mounting can be used; for individual components with higher positional accuracy requirements, a manual chip mounting machine can also be used.
3. Soldering: Generally, reflow soldering is used; in special cases, spot welding can also be used.
2. High-Precision Mounting in SMT Processing
Features: The FPC must have MARK marks for substrate positioning, and the FPC itself must be flat. FPC fixing is difficult, and consistency is difficult to ensure during mass production, requiring high equipment requirements. In addition, the control difficulty of solder paste printing and mounting processes is high.
Key Processes: 1. FPC Fixing: Fixed to the tray from printing and mounting to reflow soldering. The trays used require a low coefficient of thermal expansion. There are two fixing methods. For QFP lead pitch with mounting accuracy of 0°, the above method A is used; for QFP lead pitch with mounting accuracy of 0°, the below method B is used; Method A: Place the tray on the positioning template. Fix the FPC to the tray with thin, high-temperature resistant adhesive tape, then separate the tray from the positioning template for printing. The high-temperature resistant adhesive tape should have moderate viscosity, must be easily peeled off after reflow soldering, and there should be no residual adhesive on the FPC.
Solder Paste Printing: Because the FPC is loaded on the tray, and there is high-temperature resistant adhesive tape for positioning on the FPC, resulting in inconsistent height with the tray plane, an elastic squeegee must be used for printing. The composition of the solder paste greatly affects the printing effect, and the appropriate solder paste must be selected. In addition, the printing template using method B needs special processing.
Mounting Equipment: First, the solder paste printer, the printer needs to be equipped with an optical positioning system, otherwise the welding quality will be greatly affected. Second, the FPC is fixed on the tray, but there will always be some small gaps between the FPC and the tray, which is a major difference from the PCB substrate. Therefore, the setting of equipment parameters will have a great impact on the printing effect, mounting accuracy, and welding effect. Therefore, FPC mounting requires strict process control.
RECOMMENDED NEWS
High-end Custom Services: SMT Chip Processing Meets Diverse Industry Needs
(Telephone contact)
Email:
Address： Room 502, Building 1, No. 13, Bohua 4th Road, Huangpu District, Guangzhou City
COPYRIGHT © 2025 Guangzhou Tongsen Electronic Technology Co., Ltd. All rights reserved.