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A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "E：Engineering and Technology".

Deadline for manuscript submissions: closed (5 February 2023) | Viewed by 25861

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Special Issue Editors

Dr. Yang Peng

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Guest Editor

School of Aerospace Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Interests: LED/LD packaging; high-power white LED/LDs; UV-LEDs; power devices; opto-thermal performances; phosphor-in-glasses; 2D/3D ceramic substrates; LED applications
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Mingxiang Chen

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Guest Editor

School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Interests: electronic packaging and micro/nano fabrication technology; including HP LED packaging; low-temperature bonding and nano packaging; 2D/3D ceramic substrates

Prof. Dr. Fulong Zhu

E-Mail Website
Guest Editor

Institute of Microsystems, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Interests: microelectronic packaging reliability; micro-nano mechanics; micro-nano manufacturing
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Electronic devices are widely applied in daily life, the environment, life sciences, industry fields, etc., including semiconductor devices, power devices, MEMS devices, optoelectronic devices, and so on. Electronic packaging is a key process for the fabrication of devices, and its functions contain mechanical protection, electrical interconnection, performance enhancement, and heat dissipation. In order to enhance the performances and reliability of electronic devices, some advanced technologies have been proposed and developed in electronic packaging, including advanced packaging mechanisms, packaging materials, packaging structures, packaging technologies, and evaluation methods, and can be optimized by means of theoretical analysis, simulation, and experiments.

This Special Issue seeks to showcase research papers and review articles discussing recent developments and applications of advanced electronic packaging, including novel packaging materials, reliable packaging structures, advanced packaging technologies, and new applications. Areas of interest include but are not limited to:

Packaging mechanisms
Packaging modeling and simulation
Packaging materials
Structural design
Advanced packaging technologies
Packaging performances
Packaging reliability
Reliability evaluation methods
New applications

Dr. Yang Peng
Prof. Dr. Mingxiang Chen
Prof. Dr. Fulong Zhu
Guest Editors

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. Micromachines is an international peer-reviewed open access monthly 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

Electronic packaging
Semiconductor devices
Power devices
MEMS devices
Optoelectronic devices
Performances
Reliability
Applications

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Related Special Issue

Advanced Technologies in Heterogeneous Integration in Micromachines

Published Papers (10 papers)

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Research

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14 pages, 19134 KiB

Open AccessArticle

Effects of Voids on Thermal Fatigue Reliability of Solder Joints on Inner Rings in Ball Grid Array Packaging by Finite Element Analysis

by Xingwang Hu, Li Liu, Sheng Liu, Meng Ruan and Zhiwen Chen

Micromachines 2023, 14(3), 588; https://doi.org/10.3390/mi14030588 - 28 Feb 2023

Cited by 5 | Viewed by 2921

Abstract

Under alternating temperatures, the fatigue failure of solder balls caused by the mismatch of the thermal expansion coefficient is a key problem in a Ball Grid Array (BGA). However, the combined effects of the solder ball location and the size of voids within it can seriously affect the thermal fatigue reliability of BGA solder balls, which can be easily ignored by researchers. Firstly, the thermal fatigue reliability of the board-level solder balls was evaluated by a temperature cycling test of the BGA package at −20 °C–+125 °C. The experimental results showed that the thermal fatigue reliability of the outer ring’s solder joint was lower than that of the inner ring. Secondly, the reliability of the solder balls in the BGA package was studied under the same thermal cycling condition based on finite element analysis (FEA). The influences of voids on fatigue life were investigated. Generally, a linear correlation between the void content and the fatigue life of the inner rings’ solder balls could be identified with a gradually smoothed relationship for solder balls closer to the center. In addition, when the size of the void exceeded a critical volume, the inner ring’s solder ball with the void would fail before the outermost ring. The results of FEA showed that the critical void volume ratio from the second to fifth ring increased from 10.5% to 42.3%. This study provides a valuable reference for the influence of voids on the thermal fatigue reliability of BGA solder balls. Full article

(This article belongs to the Special Issue Advanced Technologies in Electronic Packaging)

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6 pages, 2961 KiB

Open AccessArticle

Fabrication of LuAG:Ce³⁺ Ceramic Phosphors Prepared with Nanophosphors Synthesized by a Sol-Gel-Combustion Method

by Seok Bin Kwon, Seung Hee Choi, Jung Hyeon Yoo, Seon Yeong Lee, Bo Young Kim, Ho Jung Jeong, Wan Ho Kim, Jae Pil Kim, Bong Kyun Kang, Dae Ho Yoon and Young Hyun Song

Micromachines 2022, 13(11), 2017; https://doi.org/10.3390/mi13112017 - 18 Nov 2022

Cited by 2 | Viewed by 1779

Abstract

The aim of this study was to investigate properties of ceramic phosphors fabricated using nano Lu₃Al₅O₁₂:Ce³⁺ phosphors produced with a sol-gel-combustion method. These nano Lu₃Al₅O₁₂:Ce³⁺ phosphors had a size of about 200 nm, leading to high density when fabricated as a ceramic phosphor. We manufactured ceramic phosphors through vacuum sintering. Alumina powder was added to improve properties. We mounted the manufactured ceramic phosphor in a high-power laser beam projector and drove it to determine its optical performance. Ceramic phosphor manufactured according to our route will have a significant impact on the laser-driven lighting industry. Full article

(This article belongs to the Special Issue Advanced Technologies in Electronic Packaging)

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14 pages, 3535 KiB

Open AccessArticle

Automatic Illumination Control Method for Indoor Luminaires Based on Multichromatic Quantum Dot Light-Emitting Diodes

by Hua Xiao, Guancheng Wang, Wenda Zhang, Sirong Lu, Bingxin Zhao, Zhanlang Wang, Yanglie Li and Jiada Liu

Micromachines 2022, 13(10), 1767; https://doi.org/10.3390/mi13101767 - 18 Oct 2022

Cited by 2 | Viewed by 1775

Abstract

Energy saving and visual comfort are two main considerations in designing of automatic illumination control systems. However, energy-saving-oriented illumination control always causes optical spectra drifting in light-conversion-material-based white light-emitting diodes (WLEDs), which are conventionally used as artificial luminaires in indoor areas. In this study, we propose a method for InP quantum dot (QD)-based WLEDs to minimize optical energy consumption by considering the influence caused by the outdoor environment and neighboring WLED units. Factors of (a) dimensions of room window and WLED matrix, (b) distance between WLED units, lighting height, species of InP QDs, and (c) user distribution are taken into consideration in calculation. Parameters of correlated color temperature (CCT) and color rendering index (Ra) of the WLED matrix are optimized according to the lighting environment to improve user visual comfort level. By dynamically controlling the light ingredients and optical power of WLEDs, we optimize the received illuminance distribution of table tops, improve the lighting homogeneity of all users, and guarantee the lowest energy consumption of the WLED matrix. The proposed approach can be flexibly applied in large-scale WLED intelligent controlling systems for industrial workshops and office buildings. Full article

(This article belongs to the Special Issue Advanced Technologies in Electronic Packaging)

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13 pages, 8393 KiB

Open AccessArticle

Promotion of High-Speed Copper-Filling Performance for Interconnections with Increasing Aspect-Ratio Using Compound Additives

by Qing Wang, Yang Peng, Yun Mou and Mingxiang Chen

Micromachines 2022, 13(9), 1539; https://doi.org/10.3390/mi13091539 - 17 Sep 2022

Cited by 3 | Viewed by 2263

Abstract

Interconnections are essential for integrating the packaging substrate, and defect-free copper-filling can further improve the reliability in through holes (THs). The coating properties and filling processes are mainly dominated by the interplays among additives in the direct current electroplating. The acidic copper sulfate electroplating solution contained three typical convection-dependent additives and chloride ions (Cl⁻). The THs with aspect ratios (ARs) of 6.25, 5, and 4.17 (thickness of 500 μm) were selected as the study subjects. The effects of Cl⁻ and ARs on the interactions among the additives were investigated in detail using electrochemical measurements, which were verified by the THs filling experiments. The additive compounds present a convection enhanced inhibition effect and cathodic polarization, leading to a copper filling capacity increase with ARs and the amelioration of copper compactness and corrosion resistance. The defect-free copper filling of THs and a uniform mirror bright surface circuit can be achieved simultaneously using compound additives at a relatively high speed. Full article

(This article belongs to the Special Issue Advanced Technologies in Electronic Packaging)

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11 pages, 3967 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Wide-Angle Mini-Light-Emitting Diodes without Optical Lens for an Ultrathin Flexible Light Source

by Yen-Lung Chen, Wen-Chung Chin, Chun-Wei Tsai, Chang-Che Chiu, Ching-Ho Tien, Zhi-Ting Ye and Pin Han

Micromachines 2022, 13(8), 1326; https://doi.org/10.3390/mi13081326 - 16 Aug 2022

Cited by 6 | Viewed by 2466

Abstract

This report outlines a proposed method of packaging wide-angle (WA) mini-light-emitting diode (mini-LED) devices without optical lenses to create a highly efficient, ultrathin, flexible planar backlight for portable quantum dot light-emitting diode (QLED) displays. Since the luminous intensity curve for mini-LEDs generally recommends a beam angle of 120°, numerous LEDs are necessary to achieve a uniform surface light source for a QLED backlight. The light-guide layer and diffusion layer were packaged together on a chip surface to create WA mini-LEDs with a viewing angle of 180°. These chips were then combined with a quantum dot (QD) film and an optical film to create a high-efficiency, ultrathin, flexible planar light source with excellent color purity that can be used as a QLED display backlight. A 6 in (14.4 cm) light source was used as an experimental sample. When 1.44 W was supplied to the sample, the 3200-piece WA mini-LED with a flexible planar QLED display had a beam angle of 180° on the luminous intensity curve, a planar backlight thickness of 0.98 mm, a luminance of 10,322 nits, and a luminance uniformity of 92%. Full article

(This article belongs to the Special Issue Advanced Technologies in Electronic Packaging)

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9 pages, 3186 KiB

Open AccessArticle

Spectra Stable Quantum Dots Enabled by Band Engineering for Boosting Electroluminescence in Devices

by Bingbing Lyu, Junxia Hu, Yani Chen and Zhiwei Ma

Micromachines 2022, 13(8), 1315; https://doi.org/10.3390/mi13081315 - 14 Aug 2022

Viewed by 2006

Abstract

The band level landscape in quantum dots is of great significance toward achieving stable and efficient electroluminescent devices. A series of quantum dots with specific emission and band structure of the intermediate layer is designed, including rich CdS (R-CdS), thick ZnSe (T-ZnSe), thin ZnSe (t-ZnSe) and ZnCdS (R-ZnCdS) intermediate alloy shell layers. These quantum dots in QLEDs show superior performance, including maximum current efficiency, external quantum efficiencies and a T₅₀ lifetime (at 1000 cd/m²) of 47.2 cd/A, 11.2% and 504 h for R-CdS; 61.6 cd/A, 14.7% and 612 h for t-ZnSe; 70.5 cd/A, 16.8% and 924 h for T-ZnSe; and 82.0 cd/A, 19.6% and 1104 h for R-ZnCdS. Among them, the quantum dots with the ZnCdS interlayer exhibit deep electron confinement and shallow hole confinement capabilities, which facilitate the efficient injection and radiative recombination of carriers into the emitting layer. Furthermore, the optimal devices show a superior T₅₀ lifetime of more than 1000 h. The proposed novel methodology of quantum dot band engineering is expected to start a new way for further enhancing QLED exploration. Full article

(This article belongs to the Special Issue Advanced Technologies in Electronic Packaging)

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12 pages, 1620 KiB

Open AccessArticle

Machine Learning to Predict Junction Temperature Based on Optical Characteristics in Solid-State Lighting Devices: A Test on WLEDs

by Mohammad Azarifar, Kerem Ocaksonmez, Ceren Cengiz, Reyhan Aydoğan and Mehmet Arik

Micromachines 2022, 13(8), 1245; https://doi.org/10.3390/mi13081245 - 2 Aug 2022

Cited by 6 | Viewed by 3004

Abstract

While junction temperature control is an indispensable part of having reliable solid-state lighting, there is no direct method to measure its quantity. Among various methods, temperature-sensitive optical parameter-based junction temperature measurement techniques have been used in practice. Researchers calibrate different spectral power distribution behaviors to a specific temperature and then use that to predict the junction temperature. White light in white LEDs is composed of blue chip emission and down-converted emission from photoluminescent particles, each with its own behavior at different temperatures. These two emissions can be combined in an unlimited number of ways to produce diverse white colors at different brightness levels. The shape of the spectral power distribution can, in essence, be compressed into a correlated color temperature (CCT). The intensity level of the spectral power distribution can be inferred from the luminous flux as it is the special weighted integration of the spectral power distribution. This paper demonstrates that knowing the color characteristics and power level provide enough information for possible regressor trainings to predict any white LED junction temperature. A database from manufacturer datasheets is utilized to develop four machine learning-based models, viz., k-Nearest Neighbor (KNN), Radius Near Neighbors (RNN), Random Forest (RF), and Extreme Gradient Booster (XGB). The models were used to predict the junction temperatures from a set of dynamic opto-thermal measurements. This study shows that machine learning algorithms can be employed as reliable novel prediction tools for junction temperature estimation, particularly where measuring equipment limitations exist, as in wafer-level probing or phosphor-coated chips. Full article

(This article belongs to the Special Issue Advanced Technologies in Electronic Packaging)

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10 pages, 4153 KiB

Open AccessArticle

Enhancing Heat Dissipation of Photoluminescent Composite in White-Light-Emitting Diodes by 3D-Interconnected Thermal Conducting Pathways

by Puzhen Xia, Bin Xie and Xiaobing Luo

Micromachines 2022, 13(8), 1222; https://doi.org/10.3390/mi13081222 - 30 Jul 2022

Cited by 1 | Viewed by 1767

Abstract

The photoluminescent composite, which consists of micro-/nanoscale photoluminescent particles and a polymer matrix, plays a key role in optical wavelength conversion in white-light-emitting diodes (WLEDs). Heat is inevitably generated within the composite due to the energy lost through conversion and cannot be easily dissipated due to the extremely low thermal conductivity of the polymer matrix. Consequently, the composite suffers from a high working temperature, which severely deteriorates its optical performance as well as its long-term stability in WLEDs. To tackle this thermal issue, in this work three-dimensional (3D)-interconnected thermal conducting pathways composed of hexagonal boron nitride (hBN) platelets were constructed inside a photoluminescent composite, using a simplified bubbles-templating method. The thermal conductivity of the composite was efficiently enhanced from 0.158 to 0.318 W/(m∙K) under an ultralow hBN loading condition of 2.67 wt%. As a result, the working temperature of the photoluminescent composite in WLEDs was significantly reduced by 32.9 °C (from 102.3 °C to 69.4 °C, under 500 mA). Therefore, the proposed strategy can improve the heat accumulation issue in photoluminescent composites and thus improve the optical stability of WLEDs. Full article

(This article belongs to the Special Issue Advanced Technologies in Electronic Packaging)

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10 pages, 3685 KiB

Open AccessArticle

Effects of Bonding Materials on Optical–Thermal Performances and High-Temperature Reliability of High-Power LED

by Jiaxin Liu, Yun Mou, Yueming Huang, Jiuzhou Zhao, Yang Peng and Mingxiang Chen

Micromachines 2022, 13(6), 958; https://doi.org/10.3390/mi13060958 - 17 Jun 2022

Cited by 10 | Viewed by 2589

Abstract

The die-bonding layer between chips and substrate determinates the heat conduction efficiency of high-power LED. Sn-based solder, AuSn20 eutectic, and nano-Ag paste were widely applied to LED interconnection. In this paper, the optical–thermal performances and high-temperature reliability of LED with these bonding materials have systematically compared and studied. The thermal conductivity, electrical resistivity, and mechanical property of these bonding materials were characterized. The LED module packaged with nano-Ag has a minimum working temperature of 21.5 °C. The total thermal resistance of LED packaged with nano-Ag, Au80Sn20, and SAC305 is 4.82, 7.84, and 8.75 K/W, respectively, which is 4.72, 6.14, and 7.84 K/W higher after aging for 500 h. Meanwhile, the junction temperature change of these LEDs increases from 2.33, 3.76, and 4.25 °C to 4.34, 4.81, and 6.41 °C after aging, respectively. The thermal resistance of the nano-Ag, Au80Sn20 and SAC305 layer after aging is 1.5%, 65.7%, and 151.5% higher than before aging, respectively. After aging, the LED bonded with nano-Ag has the better optical performances in spectral intensity and light output power, which indicates its excellent heat dissipation can improve the light efficiency. These results demonstrate the nano-Ag bonding material could enhance the optical-thermal performances and high-temperature reliability of high-power LED. Full article

(This article belongs to the Special Issue Advanced Technologies in Electronic Packaging)

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36 pages, 4899 KiB

Open AccessFeature PaperEditor’s ChoiceReview

A Critical Review on the Junction Temperature Measurement of Light Emitting Diodes

by Ceren Cengiz, Mohammad Azarifar and Mehmet Arik

Micromachines 2022, 13(10), 1615; https://doi.org/10.3390/mi13101615 - 27 Sep 2022

Cited by 15 | Viewed by 4316

Abstract

In the new age of illumination, light emitting diodes (LEDs) have been proven to be the most efficient alternative to conventional light sources. Yet, in comparison to other lighting systems, LEDs operate at low temperatures while junction temperature (T_j) is is among the main factors dictating their lifespan, reliability, and performance. This indicates that accurate measurement of LED temperature is of great importance to better understand the thermal effects over a system and improve performance. Over the years, various T_j measurement techniques have been developed, and existing methods have been improved in many ways with technological and scientific advancements. Correspondingly, in order to address the governing phenomena, benefits, drawbacks, possibilities, and applications, a wide range of measurement techniques and systems are covered. This paper comprises a large number of published studies on junction temperature measurement approaches for LEDs, and a summary of the experimental parameters employed in the literature are given as a reference. In addition, some of the corrections noted in non-ideal thermal calibration processes are discussed and presented. Finally, a comparison between methods will provide the readers a better insight into the topic and direction for future research. Full article

(This article belongs to the Special Issue Advanced Technologies in Electronic Packaging)

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