Sn-coated Cu Microparticle Paste for High Power Device Packaging

A Sn-coated Cu microparticle is prepared in this work, which can achieve the aims of low bonding temperatures and high working temperatures of the die attach materials. The Sn-coated Cu microparticles with an average particle size of 1 μm and good dispersibility were fabricated by electroless plated method. After electroless plated, few intermetallic compounds (Cu
₆
Sn
₅
) were already formed. When the bonding temperature reached to 280°C, the Sn layer completely melted and transformed to IMCs (Cu
₆
Sn
₅
and Cu
₃
Sn). The Cu core is surrounded by the melten Sn layer tightly, which form a dense sintered network structure. After sintering at 280°C, the average mechanical strength of testing bonding joints was 21.16 MPa. The interconnection image of the bondlines illustrated few voids and cracks, indicates the excellent bonding quality.