What Performance Characteristics Should Flux Have In SMT Processing?

In order to obtain a good no-clean effect in the SMT chip processing, two parameters, namely the solid content and the amount of flux applied, must be strictly controlled. The main active ingredient in the flux is rosin. The rosin will decompose at around 280 degrees Celsius. Therefore, the temperature of the tin furnace should not be too high. Flux is a chemical that promotes soldering. It is an indispensable auxiliary material in welding and its role is very important.

 

Performance characteristics of flux in SMT patch:

 

1, should have good thermal stability, the general thermal stability temperature is not lower than 100 °C.

 

2. The flux should have an appropriate range of active temperatures. It begins to function before the solder melts and acts to remove the oxide film and reduce the surface tension of the liquid solder during the soldering process. The melting point should be lower than the melting point of the solder, but should not be too large.

3. The density of the flux should be less than the density of the liquid solder so that the flux is evenly distributed over the metal surface to be soldered, covering the solder surface and the metal to be soldered. The film form effectively shields air and promotes solder to the substrate. wet.

4. The residue after welding should not be corrosive and easy to clean; no toxic and harmful gas should be precipitated; water solubility and insulation resistance meet the requirements of the electronic industry; no moisture absorption, no mold; stable chemical properties, easy to store.