Six Rework and Repair Skills for Bad SMT

Usually, after reflow soldering, the yield rate of PCB cannot reach 100%, and some defects will appear more or less. Among these defects, some are surface defects, which only affect the surface appearance of solder joints, but do not affect the function and life of the product. However, some defects will seriously affect the function and life of the product, such as: misalignment, bridge connection, etc. Such defects must be reworked and repaired. Do you know any skills for reworking and repairing bad SMT?

1. Manual rework and repair and soldering should follow the principle of SMT components first small and then large, first low and then high. First solder chip resistors, chip capacitors, transistors, then solder small IC devices, large IC devices, and finally solder plug-ins.

2. When soldering chip components, the width of the soldering bit should be consistent with the width of the components. If it is too small, it will not be easy to position when soldering.

3. When soldering SOP, QFP, PLCC and other devices with pins on two or four sides, several positioning points should be soldered on both sides or four sides first. After careful inspection to confirm that each pin matches the corresponding pad, drag soldering is performed to complete the soldering of the remaining pins.

4. The speed should not be too fast when dragging soldering, just drag 1-2 solder joints in about 1s or so.

5. After soldering, use a magnifying glass of 4 to 6 times to check whether there is any bridge between the solder joints, and the soldering of the same part shall not exceed twice in a row. If it is not welded well once, it should be cooled before soldering to prevent the pad from falling off.

6. When soldering IC devices, evenly apply a layer of solder paste on the pad, which can not only infiltrate and flux the solder joints, but also improve maintenance efficiency.

SHENZHEN HOYOGO ELECTRONIC TECHNOLOGY CO., LTD. is a company that specializes in providing overall PCBA electronics manufacturing services, including one-stop services from upstream electronic component procurement to PCB production and processing, SMT, DIP plug-in, PCBA testing, and finished product assembly.