A solder paste comprising a powder of a Zn-containing Sn-based, lead-free solder mixed with an activator-containing rosin-based flux to which 0.5-10.0 wt % of isocyanuric acid or a haloalkyl ester thereof is added can prevent the formation of solder balls and voids during reflow soldering and exhibit good solderability. A solder paste comprising a powder of an Ag- or Zn-containing Sn-based, lead-free solder mixed with an activator-containing rosin-based flux to which 0.01-10.0 wt % of a salicylamide compound also does not exhibit a change in viscosity and exhibits good solderability.
1. A solder paste comprising a powder of an Sn-based, lead-free solder mixed with a rosin-based flux, the rosin-based flux containing 0.01-10.0 wt % of at least one salicylamide compound selected from salicylamide and derivatives thereof.
2. A solder paste as claimed in claim 1 wherein the lead-free solder is selected from an Ag-containing Sn-based solder and a Zn-containing Sn-based solder.
3. A solder paste as claimed in claim 2 wherein the Zn-containing Sn-based solder further contains Bi.
4. A solder paste as claimed in claim 2 wherein the Ag-containing Sn-based solder further contains Cu.
5. A solder paste as claimed in claim 1 wherein the salicylamide compound is selected from salicylamide, decamethylenedicarboxylic acid disalicyloyl hydrazide, and 3-(N-salicyloyl)-amino-1, 2, 4-triazole.
6. A solder paste as claimed in claim 1 , wherein the rosin-based flux further contains 0.5-10.0 wt % of at least one isocyanuric compound selected from isocyanuric acid and derivative thereof having no hydroxyl group.
7. A solder paste as claimed in claim 6 wherein the lead-free solder is a Zn-containing Sn-based solder.
8. A solder paste as claimed in claim 7 wherein the Zn-containing Sn-based solder further contains Bi.
9. A solder paste as claimed in claim 6 wherein the isocyanuric compound is selected from isocyanuric acid and an isocyanuric acid tris(haloalkyl) ester.
10. A solder paste as claimed in claim 6 wherein the rosin-based flux contains an activator.
11. A solder paste as claimed in claim 1 wherein the rosin-based flux contains an activator.
12. A solder paste as claimed in claim 11 wherein the activator comprises at least one organic amine hydrohalide.