Rapid Formation of Full Intermetallic Bondlines for Die Attachment in High-Temperature Power Devices Based on Micro-sized Sn-Coated Ag Particles
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A new die attach material prepared by pressing micro-sized Sn-coated Ag powders as a preform is proposed for high-temperature power device packaging. The Sn-coated Ag powders were completely transformed into Ag3Sn with a melting point of 480°C after bonding at 250°C for 10 min, subsequently producing a bondline which can sustain a much higher temperature than the processing temperature. The detailed microstructural analysis indicates that a fine-grained full Ag3Sn bondline with high-density twin boundaries can be formed in a short reflow time, which contributes to the improved performance of the full Ag3Sn bondline, with an average shear strength of 37.5 MPa at 400°C. Nano-indentation testing showed that the average hardness and elasticity modulus of the prepared full Ag3Sn bondline were 3.1 ± 0.26 GPa and 84.56 ± 6.13 GPa, respectively. The electrical resistivity was measured to be 11.42 μΩ cm. The shear strength at 400°C was kept above 20 MPa after aging at 200°C for 200 h due to the thermostability of Ag3Sn microstructure in the bondlines.
This work is financially supported by the Science and Technology Project of Shenzhen (No. JCYJ20160318095308401).
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