The circuit board design and production process has as many as 20 processes. Poor tinning is really a headache. Poor tin on the circuit board may cause such as circuit sand holes, chipping, circuit dog teeth, open circuit, and circuit sand holes. Wire; if the hole is too thin, there will be no copper; the tin stripping is not clean (the number of tin stripping will affect the uncleanness of the plating layer) and other quality problems, so encountering poor tinning often means re-soldering or even abandonment of previous efforts , Needs to be remade.
The circuit board can not be well tinned during SMT production. Generally, the poor tinning is related to the cleanliness of the bare circuit board surface. If there is no dirt, there will be basically no poor tinning. Poor flux, temperature, etc. when tinning.
Reasons for poor tin on circuit boards:
1. There are particles in the plating layer on the board, or there are grinding particles left on the surface of the circuit during the manufacturing process of the substrate.
2. There are grease, impurities and other sundries on the board surface, or there is residual silicone oil.
3. There are flakes on the surface of the board without tin, and there are particulate impurities in the plating layer on the board.
4. The high-potential coating is rough, there is a burning phenomenon, and the surface of the board has flakes and cannot be tinned.
5. The tin surface of the substrate or parts is oxidized and the copper surface is dull.
6. The coating on one side is complete, and the coating on the other side is poor. There is obvious bright edge on the edge of the low potential hole.
7. There are obvious bright edges on the edges of low-potential holes, and the high-potential coatings are rough and burnt.
8. There is not enough temperature or time guaranteed during the soldering process, or the flux is not used correctly.
9. A large area of low potential cannot 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.