PCB circuit board common problems and solutions
First, Dark and granular contacts appear on the PCB circuit board
PCB boards have dark or small grain joints. Most of them are caused by solder contamination and excessive oxides in the tin. The solder joint structure is too brittle. Be careful not to use low tin content. The dark color caused by solder is confused.
Another reason is that the composition of the solder used in the PCB manufacturing process changes, the impurity content is too much, and it is necessary to add pure tin or replace the solder. Physical changes in the layered glass fiber layer, such as separation between layers, but this situation is not a bad solder joint, because the substrate is too hot, need to reduce the preheating and soldering temperature or no judgment and substrate speed.
Second, the PCB circuit board solder joint turns golden yellow
In general, the solder of the PCB board is silver-gray, but occasionally there are golden solder joints. The main reason for this problem is that the temperature is too high, and only the temperature of the tin furnace needs to be lowered.
Third, PCB circuit board short circuit:
PCB circuit board short circuit is one of the common faults that cause the PCB board to work, and the biggest cause of this problem is improper solder pad design. Solution: The circular pad can be changed to an elliptical shape to increase the distance between the point and the point to prevent short circuit.
The design of the PCB board part is not appropriate, and it will also cause the board to be short-circuited and unable to work. If the foot of SOIC is parallel to the tin wave, it will easily cause a short circuit accident. Solution: It can be modified if the part is removed, so it is easy to cause a short circuit. The solder joint needs to be more than 2mm away from the line.
In addition, there are some reasons that may cause short-circuit failure of the PCB board, such as too large substrate hole, too low tin furnace temperature, poor solderability of the board surface, solder mask failure, board surface contamination, etc., which are common faults. the reason. Engineers can eliminate and check the above reasons and faults one by one.
The design and production of PCB circuit boards is a simple and cumbersome task. It is inevitable that some problems will arise. The production personnel need to understand the causes and solutions of the problems, in order to better avoid the PCB board problems.