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Previously I was using traditional soldering wire 60/40 Sn/Pb (stannous)(lead). Restriction of Hazardous Substances (RoHS) says that Pb (lead) is dangerous for environment. So we should not use lead. When I searched a little, I saw that there was soldering in a wide variety of mixtures and I was a little confused. There is (video link) a wide variety of soldering wire examination,

Sn 99.3 Cu 0.7 the link

Sn 96,5 Ag 3 Cu 0,5 the link

2% Silver Solder Wire the link

at the video, if i don't get it wrong, He is saying solder wire with silver are better. I want to learn key factor of silver at solder wire. also some solder wire has copper, What is the benefit of 0.5 copper?

I am using solder wire for general purpose such as PCB, on circuit boards. Which mixture should I choose while soldering? I think this solder is the best Sn 96,5 Ag3 Cu 0,5

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    \$\begingroup\$ I believe the copper is to reduce the amount of copper that it would otherwise dissolve from the PCB traces. \$\endgroup\$
    – DKNguyen
    Commented Mar 9, 2020 at 18:22
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    \$\begingroup\$ And your soldering iron tip. \$\endgroup\$
    – rdtsc
    Commented Mar 9, 2020 at 19:10

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The copper keeps the silver solder from leaching copper away from the PCB foil. Sn99.3 Cu 0.7 is cheaper so it's popular for consumer products but it's not quite as good to work with as the solder containing silver.

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    \$\begingroup\$ So is this Sn 96,5 Ag3 Cu 0,5 better for me? \$\endgroup\$
    – mehmet
    Commented Mar 10, 2020 at 6:39
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    \$\begingroup\$ Probably a bit better. Neither one will give you a nice shiny joint like Sn63Pb37 and it's not quite eutectic but it has about 10°C lower melting point than the Sn99.3 Cu0.7, but much (35°C) higher than Sn63Pb37 solder. There are some mechanical/metallurgical differences that you will probably not notice in casual use. \$\endgroup\$
    – Spehro 'speff' Pefhany
    Commented Mar 10, 2020 at 7:22
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    \$\begingroup\$ after buying Sn 96,5 Ag3 Cu 0,5 it looks matt but strong. \$\endgroup\$
    – mehmet
    Commented Mar 13, 2020 at 9:16

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