SMT patch processing should pay attention to the welding matters
1. Pay attention to the following points when welding.
1 general solder joints The entire soldering operation time is controlled at 2~3s.
2 The time between each welding step is crucial to ensure the quality of the welding, and it needs to be mastered through practice.
3 After the welding operation is completed, the position of the welded part cannot be changed until the solder paste material has not completely solidified.
2, welding precautions for discrete components
The soldering of discrete components is at the heart of the entire electronics. In addition to mastering the essentials of soldering operations, it is also necessary to pay attention to the following aspects:
(1) The soldering iron should generally be selected from the internal heat type (20~35W) or the constant temperature type, and the temperature should not exceed 300 °C. A small cone tip is generally used.
(2) When heating, try to make the tip of the soldering iron contact the copper foil and component pins on the printed circuit board at the same time. For the diameter of more than 5mm, the pad can be rotated around the pad.
(3) When the two or more printed circuit boards are soldered, the pad holes are also wetted and filled.
(4) After soldering, the excess pins should be cut off and the printed circuit board should be cleaned with a cleaning solution.
(5) The most common electronic components on printed circuit boards are resistors, capacitors, inductors, diodes, etc. The soldering methods for SMT chip processing of these components are basically the same.
3. Precautions when installing and soldering integrated circuits
The method of inserting and soldering integrated circuits and the method of inserting and soldering discrete components are generally the same, except that the number of pins of the integrated circuit is relatively large, and it is necessary to be more careful when inserting or soldering the integrated circuit. In general, different printed circuit board integrated circuits are inserted in different ways. In order to make the integrated circuit more well-dissipated, an integrated circuit socket is mounted on the bottom of the integrated circuit, and the integrated circuit is fixed through the integrated circuit socket.
The integration of the integrated circuit is high, and it is easily damaged by excessive heat. It must not withstand temperatures above 200 degrees, so care must be taken when welding. In addition to mastering the basics of soldering operations during soldering, special attention must be paid to the following points.
1 Do not use a knife to scrape the gold-plated circuit pins. Just scrub with alcohol or use a drawing eraser.
2 Do not remove the pre-set short-circuit line before soldering the CMOS circuit.
3 Welding time is as short as possible, generally no more than 3s.
4 The soldering iron used is preferably a 230 degree thermostat.
5 Workbench is best to do anti-static treatment.
6 Use a narrow tipped iron tip that will not touch adjacent ends when soldering.
7-pin safety soldering sequence is ground--output---power terminal---input