BACKGROUND:  The European Union Congress has banned the use of lead-based (Pb-based) solder in consumer electronic devices, driving many companies to adopt Pb-free solders. However, current Pb-free solders are mechanically unreliable as they produce highly fragile intermetallic compound (IMC) solder joints. Fracture toughness is a critical issue especially in handheld consumer electronics where items are routinely dropped during their service life.

INNOVATION:  Researchers at UCLA have developed a method to strengthen Pb-free solder joints by adding small quantities of contoured-surface nanowires to the IMC matrix. The composite provides very strong impact fracture toughness, which prevents shearing along the interface. Furthermore, since only small quantities of nanowires are required, the proposed technique provides an affordable solution that meets the new safety regulations.

POTENTIAL APPLICATIONS 

• Pb-free electronic packaging
  • Chip connection, board-level packaging

ADVANTAGES

• Compatible with current packaging techniques
• High mechanical strength and fracture toughness
• Low implementation cost

Reference: UCLA Case No. 2009-586