Problems with solder materials, Sn-3Ag in lead-free solder, the proportion of tin, and the proportion of silver. A: You mentioned 3AG above, the ratio of silver is 3, and there are many types of lead-free alloys on the market: SN AG CU (Silver, silver and copper). And SN (tin) AG (silver) CU (copper) The general tin-silver-copper alloy is: tin 96.5 silver 3.0 copper 0.5 This alloy contains silver high so the price is high. There is also tin-copper: SN96.5 CU 3.5