You're creating a new alloy on the surface of your board. The alloy will have a melting point determined by the constituent metals of the alloy. Your alloy consists of: * Lead-free HASL solderability protection on the board * Lead-free solder paste * Solderability protection on the components that can be lead-free or not * Other stuff
Your MP+10*C rule ["solder paste is that peak temperature must be with 10 degree higher than melting point temperature (219 +10= 229)"] is sketchy. You leave no room for variation. For instance: How tight can you hold that 230*C peak of your oven? I suggest "melting point + 20*C." Sounds like you have the wrong fluid in your oven. SB "HS" rather than "LS." Look here: http://www.torenko.com/pdf/Todays-Vapor-Phase-Soldering-Tech-Paper.pdf
BR davef
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