What Are The Common Problems With SMT Processing?

In smt patch processing and soldering technology, there are several common problems with tin beads:

 

1. Preheating of the PCB board during reflow soldering is not enough;

 

2. The reflow soldering temperature curve is unfairly set, and the surface temperature of the board before entering the soldering zone has a large interval from the temperature of the soldering zone;

 

3. Solder, solder paste can not fully recover to room temperature when it is pulled out from the cold storage;

 

4. The exposure time after the solder paste is opened is exposed to the air;

 

5. When placing the patch, the tin powder splashes onto the surface of the PCB;

6. Oil or moisture adheres to the PCB during printing or transfer;

 

7. The distribution of the flux itself in the solder paste is unfair and it is difficult to evaporate the solvent or liquid additive or activator.

 

The first and second reasons above can also clarify why new alternative solder pastes are prone to such problems. The main reason is that the current temperature profile does not match the solder paste used.

The third, fourth, and sixth reasons may be improperly manipulated by the user; the fifth reason is that the solder paste is not sticky or sticky due to improper storage of the solder paste or failure to form solder paste during the shelf life. Low, tin powder splashing during patching; the seventh reason is formed by the solder paste supplier's own production technology.

 

There is more residue on the SMT surface after soldering: more residue remains on the PCB surface after soldering. This is also a problem that customers often reflect. The presence of more residue on the surface of the board can affect the brightness of the board surface. It also has a certain impact on the electrical properties of the PCB itself; the main reasons for the formation of more residues are as follows: when the solder paste is applied, the customer's board condition and customer needs, or other reasons for selecting the fault, there is too much rosin in the solder paste. Poor resin or quality.