CHAPTER 5 SOLDER JOINT RELIABILITY

The reliability results of mounting a lead type lead-free product using Sn-3Ag-0.5Cu solder under various temperatures and then evaluating the lead connection strength after temperature cycle testing are shown below.
Looking at these results, we can see a tendency toward lower strength as the number of temperature cycles is increased, regardless of whether the lead material is Cu or Fe-Ni.
If the lead material is Cu, the lead connection strength tends to be somewhat higher at lower soldering temperatures, and if the lead material is Fe-Ni, it ends to be somewhat higher at higher soldering temperatures.

♦ Aging conditions     • PCT4h       (105°C, 100%RH, 1.22 x 105Pa) ♦ Temperature cycling test conditions     • -40 to 125°C/10 minutes ♦ Package     • 28 x 28mm, 208 pin QFP, 0.5mm pitch     • Lead material: Cu/Fe-Ni     • Plating: Sn-Bi ♦ Printed wiring board     • Size: 125 x 125 x t1.6mm     • Material: FR-4, 4 layers     • Pad surface treatment: Pre-flux ♦ Stencil     • Thickness: 150µm ♦ Solder paste     • Sn-3Ag-0.5Cu ♦ Soldering temperature (leads)     • 230/245/260°C ♦ Lead pull test conditions:     • 45° direction, 5 mm/minute