No, I am not talking about Lead free vs Leaded solder. I am talking about the very same solder behaving different.
I got my solder wire (Sn38Pb60Cu2 + rosin core) fresh new, put the tip of my iron at 340ºC and I heat the solder (and the parts where it's going to go) to melt it nicely and quickly. If I do the job in less than 7s I would say, the solder ends up shiny and nice. All fantastic.
However, if I keep "playing" with it, melt it down, let it cool, melt it again because I did something wrong or need to adjust one leg or pin or the cable is not fully inserted or whatever, there's a certain point at which the finish starts to go dull. Then, no matter what I do, it says dull forever unless I replace that solder by new one.
My question is...
1. Why does this happen? The Sn + Pb + Cu don't evaporate, and the only thing smoking (evaporating) is the rosin I guess.
I've thought several times may be it's the rosin, but then I add to the dull solder a lot of rosin (flux) and no matter what, it stays dull.
2. Why does it become dull? What it means, what's really going on chemically or physically to the solder?
Since the composition is the same alloy except for the rosin part, but adding it does not change anything.
I got my solder wire (Sn38Pb60Cu2 + rosin core) fresh new, put the tip of my iron at 340ºC and I heat the solder (and the parts where it's going to go) to melt it nicely and quickly. If I do the job in less than 7s I would say, the solder ends up shiny and nice. All fantastic.
However, if I keep "playing" with it, melt it down, let it cool, melt it again because I did something wrong or need to adjust one leg or pin or the cable is not fully inserted or whatever, there's a certain point at which the finish starts to go dull. Then, no matter what I do, it says dull forever unless I replace that solder by new one.
My question is...
1. Why does this happen? The Sn + Pb + Cu don't evaporate, and the only thing smoking (evaporating) is the rosin I guess.
I've thought several times may be it's the rosin, but then I add to the dull solder a lot of rosin (flux) and no matter what, it stays dull.
2. Why does it become dull? What it means, what's really going on chemically or physically to the solder?
Since the composition is the same alloy except for the rosin part, but adding it does not change anything.