PCB News - What are the causes of poor tin on circuit boards and how to prevent them

What are the causes of poor tin on circuit boards and how to prevent them

The circuit board will not be well tinned during SMT production. Generally, poor tinning is related to the cleanliness of the bare board surface of the PCB circuit board. If there is no dirt, there will be basically no poor tinning. Second, Poor flux and temperature during soldering. So where are the common electrical tin defects in circuit board production and processing? How to solve this problem?

1. The tin surface of the substrate or parts is oxidized and the copper surface is dull.

2. The coating on one side is complete, the coating on the other side is poor, and there is obvious bright edge on the edge of the low-potential hole.

3. There are flakes on the surface of the circuit board without tin, and the coating on the surface of the circuit board has granular impurities.

4. Grease, impurities and other sundries are attached to the circuit board surface, or there is residual silicone oil.

5. The high-potential coating is rough and there is burning phenomenon, and there are flakes on the surface of the circuit board without tin.

6. There are obvious bright edges on the edges of low-potential holes, and the high-potential coating is rough and burnt.

7. There is no guarantee of sufficient temperature or time during the soldering process, or the soldering flux is not used correctly.

8. There are particulate impurities in the plating layer of the circuit board, or grinding particles are left on the surface of the circuit during the manufacturing process of the substrate.

9. Low-potential large area can not be plated with tin, and the surface of the board is slightly dark red or red, with a complete coating on one side and a poor coating on the other side.

The improvement and prevention plan of PCB circuit board electric tin defects:

1. Strengthen the pre-plating treatment.

2. Use soldering flux correctly.

3, Hexcel cell analysis to adjust the content of the light agent.

4. Check the anode consumption from time to time and add anodes reasonably.

5. Reduce the current density, and regularly maintain the filter system or perform weak electrolysis treatment.

6. Strictly control the storage time and environmental conditions of the storage process, and strictly operate the production process.

7. Regular chemical analysis and analysis of the ingredients of the syrup are added in time, increasing the current density, and prolonging the plating time.

8. Control the temperature of the PCB circuit board at 55-80°C during the soldering process and ensure sufficient preheating time.

9. Use a solvent to clean the sundries. If it is silicone oil, then you need to use a special cleaning solvent for cleaning.

10. Reasonably adjust the distribution of anodes, appropriately reduce the current density, rationally design the wiring or splicing of the circuit board, and adjust the light agent.

The above content is the analysis and summary of the Shenzhen PCB manufacturer. Of course, there may be bad soldering products that are not mentioned in the article. Welcome customers and colleagues to add.