Hello and happy new year!
I would like to know what actually happens during soldering with flux.
I've learn that flux has two major roles; 1. it becomes corrosive at high temperature thus any dirt and oxide film on the metal pad of PCB will be gone when it is touched with heated solder iron before it evaporates. 2. It reduces surface tension of the melted solder thus solder can easily flow with the flux.
Based on these knowledge, I imaged what happens during soldering as described below. (It is the situation that the pad of the PCB and surrounding area like solder mask is applied by flux and the solder is melted and stayed on the solder iron tip then the tip is touching the pad and flux right now)
1. As temperature of flux rapidly rises, the flux becomes corrosive so any dirt things on the pad including oxidized surface is gone. At the same time, liquefied solder starts to flow along the flux due to the fact that flux reduces surface tension of the liquid solder.
2. As temperature of flux rises more and more evaporation begins. The evaporation help solder to touch pad as flux between solder and pad is gone.
3. Once some portion of solder stays on the pad, its surface tension pulls rest of the solder thus good blob of solder is made on the pad.
Is my imagination right or there are more process I have to take into account?
And I have one more question about liquid type flux as I'm using now. Does it also have same function to other flux like rosin? What make it different from the other?
I would like to know what actually happens during soldering with flux.
I've learn that flux has two major roles; 1. it becomes corrosive at high temperature thus any dirt and oxide film on the metal pad of PCB will be gone when it is touched with heated solder iron before it evaporates. 2. It reduces surface tension of the melted solder thus solder can easily flow with the flux.
Based on these knowledge, I imaged what happens during soldering as described below. (It is the situation that the pad of the PCB and surrounding area like solder mask is applied by flux and the solder is melted and stayed on the solder iron tip then the tip is touching the pad and flux right now)
1. As temperature of flux rapidly rises, the flux becomes corrosive so any dirt things on the pad including oxidized surface is gone. At the same time, liquefied solder starts to flow along the flux due to the fact that flux reduces surface tension of the liquid solder.
2. As temperature of flux rises more and more evaporation begins. The evaporation help solder to touch pad as flux between solder and pad is gone.
3. Once some portion of solder stays on the pad, its surface tension pulls rest of the solder thus good blob of solder is made on the pad.
Is my imagination right or there are more process I have to take into account?
And I have one more question about liquid type flux as I'm using now. Does it also have same function to other flux like rosin? What make it different from the other?