Recent advances on kinetic analysis of solder joint reactions in 3D IC packaging technology

K.N. Tu; Yingxia Liu

doi:10.1016/j.mser.2018.09.002

Recent advances on kinetic analysis of solder joint reactions in 3D IC packaging technology

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

Overview

147 Scopus Citations

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Author(s)

Detail(s)

Original language	English
Pages (from-to)	1-12
Journal / Publication	Materials Science and Engineering R: Reports
Volume	136
Online published	1 Oct 2018
Publication status	Published - Apr 2019
Externally published	Yes

Link(s)

DOI	DOI https://doi.org/10.1016/j.mser.2018.09.002 Final Published version
	Check@CityULib
Link to Scopus	https://www.scopus.com/record/display.uri?eid=2-s2.0-85054071201&origin=recordpage
Permanent Link	https://scholars.cityu.edu.hk/en/publications/publication(60a06ada-357b-4b74-beb8-30b779b24cbe).html

Abstract

We review five solder joint reactions in 3D IC packaging technology which are of wide interest: (1) Scallop-type growth of Cu₆Sn₅ in solid-liquid interdiffusion reaction, (2) Whisker-type growth of Sn crystals at room temperature, (3) Layer-type intermetallic compound (IMC) growth in solid state aging, (4) Porous-type growth of Cu₃Sn in μ-bumps, and (5) Pillar-type growth of Cu/Sn IMC down to 1 μm in diameter. The first two have been well covered in books and reviews on solder joint technology, so only certain specific comments will be given here. On the other three, the layer-type IMC growth has been a long standing kinetic problem due to the extremely small concentration gradient across a stoichiometric IMC, but it has been resolved now, following Wagner's approach. The porous-type Cu₃Sn was found in 2014. Kinetically, it is a complete cellular precipitation, containing a set of lamellar pores. It is rare because up to now all cellular precipitations are incomplete. The pillar-type Cu/Sn reactions down to 1 μm in diameter were carried out in 2016. Owing to a large surface/volume ratio, the reaction is controlled by surface diffusion, accompanied by interstitial diffusion of Cu in Sn.