PCB News - Causes of bad tin on pcb board

Causes of bad tin on PCB board

The poor soldering of the PCB board is generally related to the cleanliness of the empty PCB surface. If there is no pollution, there will be basically no poor soldering. The second is that the soldering flux and temperature are bad. Then the common electrical tin defects of printed circuit boards are mainly reflected in the following points:
1. There are particulate impurities in the coating on the PCB surface, or grinding particles are left on the surface of the circuit during the manufacturing process of the substrate.
2. The tin surface of the substrate or parts is oxidized and the copper surface is dull.
3. There are flakes on the surface of the PCB board without tin, and there are particulate impurities in the coating on the surface of the circuit board.
4. There are grease, impurities and other sundries on the PCB surface, or there are residual silicone oil.
5. The high-potential coating is rough, there is burning pheanomenon, and the PCB surface has flake electricity and cannot be tinned.
6. The coating on one side is complete, and the coating on the other side is poor, and there are obvious bright edges on the edges of the low-potential holes.
7. There are obvious bright edges on the edges of low-potential holes, and the high-potential coating is rough and burnt.
8. There is no guarantee of sufficient temperature or time during the soldering process, or the soldering flux is not used correctly.
9. Tin can not be plated on a large area at low potential, 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 reasons for the poor electrical tin of PCB circuit boards are mainly reflected in the following points:
1. The anodes are too few and unevenly distributed.
2. The tinting agent is out of balance in a small amount or an excessive amount.
3. There is residual film or organic matter locally before plating.
4. The current density is too large, and the plating solution is not sufficiently filtered.
5. The composition of the bath liquid is out of balance, the current density is too small, and the plating time is too short.
6. The anode is too long, the current density is too large, the local wire density of the pattern is too thin, and the light agent is out of adjustment.
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