Bonding technology based on solid porous Ag for large area chips

doi:10.1016/j.scriptamat.2017.11.035

Scripta Materialia

Volume 146, 15 March 2018, Pages 123-127

https://doi.org/10.1016/j.scriptamat.2017.11.035 Get rights and content

Abstract

A bonding technology is introduced by using surface polished porous Ag in die-attachment structure. Bonding strength did not change much as the chip size varied from 3 × 3 mm² to 15 × 15 mm². This confirms that the technology was not influenced by the chip size, and thus can be used in large area bonding. Bonding mechanism based on stress-induced migration was discussed with the three dimensional finite element analyses. Transmission electron microscopy (TEM) observation further confirmed that single crystal hillocks and Ag particles formed at the bonding interface, bridging the interface together.

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Acknowledgments

This work was supported by the JST Advanced Low Carbon Technology Research and Development Program (ALCA) project “Development of a high frequency GaN power module package technology” (Grant No. J165101047).

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Citation Excerpt :
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Aiming for a suitable die-attached substrate for Ag-sintered joint technology during harsh operating environment, three surface finishes of sputtered Ti/Ag- layers, electroless Ni-/Pt-/Ag- layers, and electroplated Ni-/electroless Ni-/Pt-/Ag- layers were developed to directly bond copper (DBC) substrates, denoted as Ti/Ag, ENPA, and E-ENPA, respectively. The effect of the metallization layers by three deposition technologies on the Ag joint structures was systematically investigated during an extreme thermal shock test (TST) ranging from −50 to 250 °C. The mechanical behaviors and interface evolution considerably varied depending on the metallization layer used. Both ENPA and E-ENPA substrates provided a more robust initial shear strength of approximately 60 MPa. More importantly, both metallization layers were productive in restraining interfacial deformation owing to the effect of the thick Ni plating. A better performance was derived from the electroplated Ni in E-ENPA metallization with crack-less and deformation-resistant, because of electroplated Ni possessed a suitable hardness and toughness, thus the optimal stress-relaxation capability. This study provides insights to the properties of Ag-sintered joints on three metallization layers, where the metallization, mainly by electroplating, exhibited superior reliability beyond that of sputtered and electroless depositions in both strength and microstructure maintenance.

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Regular articleBonding technology based on solid porous Ag for large area chips

Abstract

Graphical abstract

Section snippets

Acknowledgments

Microelectron. Reliab.

Mater. Lett.

Microelectron. Reliab.

Microelectron. Reliab.

J. Alloys Compd.

Acta Mater.

Scr. Mater.

Acta Mater.

Mater. Lett.

Adv. Imaging Electron Phys.

Phys. Rep.

Acta Mater.

Scr. Mater.

Scr. Mater.

IEEE. Trans. CPMT

IEEE Trans. Power Electron.

Metall. Mater. Trans. B

Mater. Sci. Forum

J. Electron. Mater.

IEEE Trans. Compon. Packag. Technol.

Regular article
Bonding technology based on solid porous Ag for large area chips