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Material Interconnections and Microstructure Control-Related

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A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (31 March 2019) | Viewed by 32756

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Special Issue Editor

Prof. Dr. Katsuaki Suganuma

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Guest Editor

Osaka University, Institute of Scientific and Industrial Research, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
Interests: interface; joining; soldering; bonding; printed electronics; power electronics; packaging

Special Issue Information

Dear Colleagues,

The advancement of electronic devices requires new interconnection materials, which should possess excellent electric/thermal conductivity as well as high robustness. For instance, the next-generation power devices with wide band gap semiconductors such as SiC and GaN are capable of high-temperature operation at high frequency due to increasing power density simultaneous to high-density packing to achieve smaller and lighter electric conversion systems. Interfaces in these power devices at exposed to high temperature beyond 200 ºC, to severe thermal stress, and strong current wind. In contrast, the IoT revolution requires tremendous numbers of sensing devices, many of which cannot be exposed to the high temperature needed for soldering. The manufacturing temperature should be 150 ºC for the most part, while in some cases it should even be below 100 ºC. In addition, many IoT devices need to be wired in three dimensions or in fine pitch below 10 μm L/S. Thus, new interconnection materials/technologies and their control methods must be established based on scientific understanding of hetero-interface phenomena.

This special Issue will focus on the current researches in interconnections and their microstructural control for advancing electronic devices, including soldering, sinter joining, conductive adhesive, alternative interconnects, metallization, substrates, 3D packaging, quality, reliability, and failure analysis.

Thus, this Special Issue will assess how certain interconnect features (device metallization, interconnects, substrates, design, etc.) can influence the performance and reliability of devices. In this context, the research published in this Issue will provide considerable impact on new electronic/optical devices. It is my pleasure to invite you to submit a manuscript for this Special Issue. Full papers, communications, and reviews are all welcome.

Prof. Dr. Katsuaki Suganuma
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

metallization
soldering
sinter joining
interface
TLP bonding
conductive adhesive
substrate
simulation
microstructure
stress
reliability
thermal conductivity
electric conductivity
nondestructive testing
electromigration
chemical migration
diffusion
3D packaging
TSV

Published Papers (7 papers)

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Research

16 pages, 9346 KiB

Open AccessArticle

A Computational Thermodynamics-Assisted Development of Sn-Bi-In-Ga Quaternary Alloys as Low-Temperature Pb-Free Solders

by Chih-han Yang, Shiqi Zhou, Shih-kang Lin and Hiroshi Nishikawa

Materials 2019, 12(4), 631; https://doi.org/10.3390/ma12040631 - 20 Feb 2019

Cited by 14 | Viewed by 4955

Abstract

Low-temperature lead (Pb)-free solders are demanding in the electronic packaging industry, because it would open the door for various economic choices of polymeric materials as substrates and also revives the lower cost processes. Here, we proposed a tin–bismuth–indium–gallium (Sn-52.5Bi-2.68In-1Ga, SBIG (in wt.%)) quaternary low-temperature solder, designed based on systematic CALPHAD (CALculation of PHAse Diagram)-type thermodynamic calculations and corresponding key experiments. The solidification behavior of SBIG was carefully elaborated based on the computations using the lever rule and the Scheil model, and the experiments in terms of thermal analyses and microstructures of sample produced with step-quenching and various cooling rates. The mechanical properties of as-cast and 80 °C-annealed SBIG as well as their microstructures and fracture surfaces were evaluated in the tensile tests. The proposed SBIG solder is with a low liquidus temperature of 141.9 °C and is typically composed of the primary (Sn) phase, the (Sn) + (Bi) eutectic structure and a small amount of (Ga) phase. Air cooling has been identified as a satisfactory cooling rate, which would not lead to the formation of the brittle BiIn intermetallic compound. The as-cast SBIG solder exhibited high yield strength (YS) of 43.7 MPa, high ultimate tensile strength (UTS) of 53.3 MPa and an extremely large elongation of 97.3% as comparing to the conventional eutectic Sn-58Bi solder (YS: 43.1 MPa, UTS: 49.5 MPa, and elongation: 37.5%). However, the proposed SBIG solder does not possess qualified thermal stability, that significant degradation in both strength and elongation were observed after being subjected to extensive thermal ageing at 80 °C for 504 h. Full article

(This article belongs to the Special Issue Material Interconnections and Microstructure Control-Related)

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10 pages, 9452 KiB

Open AccessArticle

Heat-Resistant Microporous Ag Die-Attach Structure for Wide Band-Gap Power Semiconductors

by Seungjun Noh, Hao Zhang and Katsuaki Suganuma

Materials 2018, 11(12), 2531; https://doi.org/10.3390/ma11122531 - 12 Dec 2018

Cited by 13 | Viewed by 6811

Abstract

In this work, efforts were made to prepare a thermostable die-attach structure which includes stable sintered microporous Ag and multi-layer surface metallization. Silicon carbide particles (SiC_p) were added into the Ag sinter joining paste to improve the high-temperature reliability of the sintered Ag joints. The use of SiC_p in the bonding structures prevented the morphological evolution of the microporous structure and maintained a stable structure after high temperature storage (HTS) tests, which reduces the risk of void formation and metallization dewetting. In addition to the Ag paste, on the side of direct bonded copper (DBC) substrates, the thermal reliability of various surface metallizations such as Ni, Ti, and Pt were also evaluated by cross-section morphology and on-resistance tests. The results indicated that Ti and Pt diffusion barrier layers played a key role in preventing interfacial degradations between sintered Ag and Cu at high temperatures. At the same time, a Ni barrier layer showed a relatively weak barrier effect due to the generation of a thin Ni oxide layer at the interface with a Ag plating layer. The changes of on-resistance indicated that Pt metallization has relatively better electrical properties compared to that of Ti and Ni. Ag metallization, which lacks barrier capability, showed severe growth in an oxide layer between Ag and Cu, however, the on-resistance showed fewer changes. Full article

(This article belongs to the Special Issue Material Interconnections and Microstructure Control-Related)

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13 pages, 13762 KiB

Open AccessArticle

Thermal Shock Performance of DBA/AMB Substrates Plated by Ni and Ni–P Layers for High-Temperature Applications of Power Device Modules

by Chanyang Choe, Chuantong Chen, Seungjun Noh and Katsuaki Suganuma

Materials 2018, 11(12), 2394; https://doi.org/10.3390/ma11122394 - 28 Nov 2018

Cited by 31 | Viewed by 6327

Abstract

The thermal cycling life of direct bonded aluminum (DBA) and active metal brazing (AMB) substrates with two types of plating—Ni electroplating and Ni–P electroless plating—was evaluated by thermal shock tests between −50 and 250 °C. AMB substrates with Al₂O₃ and AlN fractured only after 10 cycles, but with Si₃N₄ ceramic, they retained good thermal stability even beyond 1000 cycles, regardless of the metallization type. The Ni layer on the surviving AMB substrates with Si₃N₄ was not damaged, while a crack occurred in the Ni–P layer. For DBA substrates, fracture did not occur up to 1000 cycles for all kind of ceramics. On the other hand, the Ni–P layer was roughened and cracked according to the severe deformation of the aluminum layer, while the Ni layer was not damaged after thermal shock tests. In addition, the deformation mechanism of an Al plate on a ceramic substrate was investigated both by microstructural observation and finite element method (FEM) simulation, which confirmed that grain boundary sliding was a key factor in the severe deformation of the Al layer that resulted in the cracking of the Ni–P layer. The fracture suppression in the Ni layer on DBA/AMB substrates can be attributed to its ductility and higher strength compared with those of Ni–P plating. Full article

(This article belongs to the Special Issue Material Interconnections and Microstructure Control-Related)

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7 pages, 19337 KiB

Open AccessCommunication

Correlation between the Microstructures of Bonding Interfaces and the Shear Strength of Cu-to-Cu Joints Using (111)-Oriented and Nanotwinned Cu

by Jing-Ye Juang, Chia-Ling Lu, Yu-Jin Li, K. N. Tu and Chih Chen

Materials 2018, 11(12), 2368; https://doi.org/10.3390/ma11122368 - 25 Nov 2018

Cited by 27 | Viewed by 4502

Abstract

Highly (111)-oriented Cu pillar-bumps were bonded to highly (111)-oriented Cu films at temperatures ranging from 200 °C/100 °C to 350 °C/100 °C in N₂ ambient conditions. The microstructures of the bonded interfaces affected the shear strength performance of the bonded Cu joints. The bonded interfaces at 300 °C/100 °C and 350 °C/100 °C had far fewer voids than interfaces bonded at 200 °C/100 °C and 250 °C/100 °C. In addition, grain growth took place across the bonding interfaces at temperatures above 300 °C/100 °C. The corresponding orientation map (OIM) showed the preferred orientation of large grown grains to be <100>. Shear tests revealed that the fracture mode was brittle for joints bonded at 200 °C/100 °C, but became ductile after bonded above 300 °C/100 °C. Based on the results, we found that voids and grain growth behavior play import roles in the shear strength performance of bonded Cu joints. Full article

(This article belongs to the Special Issue Material Interconnections and Microstructure Control-Related)

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Graphical abstract

11 pages, 7161 KiB

Open AccessArticle

Fabrication of (111)-Oriented Nanotwinned Au Films for Au-to-Au Direct Bonding

by John A. Wu, Chih-Yang Huang, Wen-Wei Wu and Chih Chen

Materials 2018, 11(11), 2287; https://doi.org/10.3390/ma11112287 - 15 Nov 2018

Cited by 6 | Viewed by 3418

Abstract

We reported that highly (111)-oriented nanotwinned gold can be fabricated by periodical-reverse electroplating. The as-deposited films are shown to have a strong (111) preferred orientation, increasing with the reverse current time. The ratios of I₍₁₁₁₎/I₍₂₂₀₎ and I₍₁₁₁₎/I₍₂₀₀₎ in X-ray diffraction signals indicates a strong (111) preferred orientation. Using the advantage of the fast surface diffusion of (111) plane compared to the other planes of gold, we performed direct bonding with different thicknesses. Grain growth was observed over two films’ interfaces to eliminate the bonding interface, when annealed at 250 °C for 1 h. Shear tests were performed to gain insight on the bonding quality. All the chips failed at either the silicon substrate or substrate-adhesion layer, showing possible higher strength than the tested maximum, 40.8 MPa. Full article

(This article belongs to the Special Issue Material Interconnections and Microstructure Control-Related)

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Graphical abstract

10 pages, 2719 KiB

Open AccessArticle

Imaging the Polymorphic Transformation in a Single Cu₆Sn₅ Grain in a Solder Joint

by Flora Somidin, Hiroshi Maeno, Xuan Quy Tran, Stuart D. McDonald, Mohd Arif Anuar Mohd Salleh, Syo Matsumura and Kazuhiro Nogita

Materials 2018, 11(11), 2229; https://doi.org/10.3390/ma11112229 - 09 Nov 2018

Cited by 14 | Viewed by 3384

Abstract

In-situ observations of the polymorphic transformation in a single targeted Cu₆Sn₅ grain constrained between Sn-0.7 wt % Cu solder and Cu-Cu₃Sn phases and the associated structural evolution during a solid-state thermal cycle were achieved via a high-voltage transmission electron microscope (HV-TEM) technique. Here, we show that the monoclinic η′-Cu₆Sn₅ superlattice reflections appear in the hexagonal η-Cu₆Sn₅ diffraction pattern upon cooling to isothermal 140 °C from 210 °C. The in-situ real space imaging shows that the η′-Cu₆Sn₅ contrast pattern is initiated at the grain boundary. This method demonstrates a new approach for further understanding the polymorphic transformation behavior on a real solder joint. Full article

(This article belongs to the Special Issue Material Interconnections and Microstructure Control-Related)

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Graphical abstract

12 pages, 4250 KiB

Open AccessArticle

Influence of Manufacturing Mechanical and Thermal Histories on Dimensional Stabilities of FR4 Laminate and FR4/Cu-Plated Holes

by Alexandra Rudajevová and Karel Dušek

Materials 2018, 11(11), 2114; https://doi.org/10.3390/ma11112114 - 28 Oct 2018

Cited by 11 | Viewed by 2785

Abstract

Irreversible dimension changes of an FR4 laminate board in the z-direction and FR4 laminate/Cu plated holes that depend on their manufacturing histories have been studied by thermal mechanical analysis in the temperature range from room temperature to 240 °C. It is found that the compression residual stresses generated in both materials due to manufacturing pressing are released during heating, leading to an elongation in the specified direction. This increase depends on the composition of the studied composite and number of pressing cycles. The second reason for the observed dimensional changes is insufficient curing during manufacture that causes post-curing after the first heating cycle and related board shrinkage in the z-direction. The temperature regions of these two processes are not the same. The post-curing process occurs in the transition temperature range (near the glass transition temperature), whereas the release of the compression residual stress is observed at higher temperatures. Both these processes are temperature-dependent and do not proceed to completion during one heating cycle. Moreover, the compression residual stress strongly influences the post-curing process. Full article

(This article belongs to the Special Issue Material Interconnections and Microstructure Control-Related)

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