Preliminary Die Shear Test of SiC Die With Patterned Pt Metallization Attached to (Au)Pt/HTCC Alumina

Gold (Au) thick-film paste based conductive die-attachment has been previously demonstrated for packaging silicon carbide (SiC) ICs with TaSi2/Pt/Ir/Pt electrical contact metallization for 10,000 hours continuous electrical operation in 500 °C air ambient without observable failure or degradation. In this paper, the die-shear strength was measured on 5 mm x 5 mm SiC die with hexagon-shaped backside multilayer TaSi2/Pt/Ir/Pt metallization patterns terminated with a thin-film Pt layer attached to Pt and Au/Pt metallized high temperature co-fired ceramic alumina (HTCC) substrates. The final attachment firing of the die-attach assemblies was at 600 °C for 3 hours in air ambient. The preliminarily measured average die-shear strength of 5 mm x 5 mm SiC attached to Pt/HTCC substrate was about 13.6 kg (> 6x105g). The die-attach assemblies with Au/Pt/HTCC alumina substrates showed ~ 39% shear strength improvement compared with those with Pt/HTCC alumina substrates. As the first step, the die shear strength per effective unit area validates the room temperature mechanical performance of the Au thick-film paste based die-attach scheme for Au or Pt terminated IC die on (Au)/Pt/HTCC substrates.
These preliminary die shear results enable the co-fired Pt/HTCC packaging process to be consistent with conventional electronic packaging sequence, ie., (Au)Pt/HTCC alumina packages with SiC ICs attached and wire-bonded can now be attached to (Au)Pt/HTCC alumina circuit boards using Au thick-film at 600 °C temperature that both SiC ICs and thermos-sonic bonding wires can withstand. This allows Au/Pt/HTCC packaged SiC ICs to become commodity products for users to test and select for subsequent installation onto multi-chip circuit boards.