CHAPTER 5 SOLDER JOINT RELIABILITY

For lead type SMD, the reliability (temp cycle) results of mounting conventional Sn-Pb plated products and lead-free Sn-Bi plated products with conventional Sn-37Pb solder and lead-free Sn-3Ag-0.5Cu solder, are shown below.
The combination of the lead-free product with the lead-free solder yielded temperature cycle characteristics superior to those of the conventional combination, and the combination of the conventional product with lead-free solder, and lead-free product with conventional solder, yielded inferior results.
Selection of the mounting part materials based on these results is recommended.

Lead material: Cu

♦ Temperature cycling test conditions     • -40 to 125°C/10 minutes ♦ Package     • 28 x 28mm, 208 pin QFP,        0.5mm pitch, Daisy chain     • Lead material: Cu     • Plating: Sn-Bi/Sn-Pb ♦ 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/Sn-37Pb ♦ Soldering temperature    (leads)     • Sn-3Ag-0.5Cu paste: Max. 245°C     • Sn-37Pb paste: Max. 220°C ♦ Failure definition     • 20% nominal resistance increase

Lead material: Fe-Ni

♦ Temperature cycling test conditions     • -40 to 125°C/10 minutes ♦ Package     • 28 x 28mm, 208 pin QFP,        0.5mm pitch, Daisy chain     • Lead material: Fe-Ni     • Plating: Sn-Bi/Sn-Pb ♦ 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/Sn-37Pb ♦ Soldering temperature    (leads)     • Sn-3Ag-0.5Cu paste: Max. 245°C     • Sn-37Pb paste: Max. 220°C ♦ Failure definition     • 20% nominal resistance increase