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Microelectronics Assembly and Packaging: Materials and Technologies

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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 (30 June 2023) | Viewed by 15853

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Dr. Liangxing Hu

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School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore
Interests: micromachining; nanofabrication; 3D integration; CMOS-MEMS stacking; advanced packaging
Special Issues, Collections and Topics in MDPI journals

Dr. Shenglin Ma

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Guest Editor

Department of Mechanical and Electrical Engineering, Xiamen University, Xiamen 361005, China
Interests: 3D (three-dimensional) integration; TSV (through-silicon via) three-dimensional integration manufacturing techniques; wafer-bonding technology; embedded microfluidic cooling technology; PMUT (piezoelectric micromachined ultrasonic transduce) and its applications
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Wenhui Zhu

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State Key Laboratory of High Performance Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China
Interests: 3D integration of micro and nano electronics; packaging reliability; atomic and molecular manufacturing

Dr. Yu Zhang

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Guest Editor

State Key Laboratory of Precision Electronic Manufacturing Technology and Equipment, Guangdong University of Technology, Guangzhou 510006, China
Interests: advanced semiconductor packaging technology and key materials for microelectronics and power electronics; micro/nano metal materials; flexible printing electronics; high density 3D interconnect technology and key materials

Prof. Dr. Fulong Zhu

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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,

With the rapid development trend of microelectronics technology, the optimization of microsystems and their different electronic components in recent years has moved towards the direction of small form factors, high bandwidths, high frequencies, high performance, high reliability, low power consumption, and low cost. Packaging materials and technologies are especially vital parts of this trend since they have essential roles in back-end processes. The further these processes develop, the more advanced packaging materials and technologies are needed. To meet the rising need for advanced systems development and to address the emerging challenges and issues facing the assembly and packaging of microelectronics, various packaging materials and technologies (2D, 2.5D, 3D, wafer-level packaging, and other advanced packaging technologies) are being developed across the industry and academia. The good news is that demands around these are rapidly increasing.

This Special Issue addresses research on microelectronics assembly and packaging, including bonding technologies (glass frit bonding, eutectic bonding, transient liquid phase diffusion bonding, adhesive bonding, fusion bonding, thermocompression bonding, hybrid bonding), 2D/2.5D/3D integration and packaging, heterogeneous integration, chiplet interconnection, and advanced packaging. Additionally, we welcome articles and reviews about electronic packaging materials such as metals, alloys, ceramics, semiconductor materials, and their characterization and qualification.

Dr. Liangxing Hu
Dr. Shenglin Ma
Prof. Dr. Wenhui Zhu
Dr. Yu Zhang
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

semiconductor packaging
advanced packaging
chip and wire bonding technology
mixed assembly technology
multichip modules (MCM)
package-on-package (PoP)
system-in-package (SiP)
heterogeneous integration
chiplet interconnection
hybrid bonding
2.5D (interposer)
3D (TSV/TGV)
packaging materials
materials qualification.

Published Papers (12 papers)

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Research

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14 pages, 13202 KiB

Open AccessArticle

Effects of Block Copolymer Terminal Groups on Toughening Epoxy-Based Composites: Microstructures and Toughening Mechanisms

by Gang Li, Wenjie Wu, Xuecheng Yu, Ruoyu Zhang, Rong Sun, Liqiang Cao and Pengli Zhu

Micromachines 2023, 14(11), 2112; https://doi.org/10.3390/mi14112112 - 17 Nov 2023

Cited by 1 | Viewed by 986

Abstract

Despite the considerable research attention paid to block copolymer (BCP)-toughened epoxy resins, the effects of their terminal groups on their phase structure are not thoroughly understood. This study fills this gap by closely examining the effects of amino and carboxyl groups on the fracture toughness of epoxy resins at different temperatures. Through the combination of scanning electron microscopy and digital image correlation (DIC), it was found that the amino-terminated BCP was capable of forming a stress-distributing network in pure epoxy resin, resulting in better toughening effects at room temperature. In a 60 wt.% silica-filled epoxy composite system, the addition of a carboxyl-terminated BCP showed little toughening effect due to the weaker filler/matrix interface caused by the random dispersion of the microphase of BCPs and distributed silica. The fracture toughness of the epoxy system at high temperatures was not affected by the terminal groups, regardless of the addition of silica. Their dynamic mechanical properties and thermal expansion coefficients are also reported in this article. Full article

(This article belongs to the Special Issue Microelectronics Assembly and Packaging: Materials and Technologies)

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12 pages, 7892 KiB

Open AccessArticle

Synthesis of Imidazole-Compound-Coated Copper Nanoparticles with Promising Antioxidant and Sintering Properties

by Yu Zhang, Xianchong Yu, Ziyuan Chen, Song Wu, Haiqi Lai, Shiwo Ta, Tingyu Lin, Guannan Yang and Chengqiang Cui

Micromachines 2023, 14(11), 2079; https://doi.org/10.3390/mi14112079 - 09 Nov 2023

Viewed by 877

Abstract

In this study, we present a facile method for preparing oxidation-resistant Cu nanoparticles through a liquid-phase reduction with imidazole compounds (imidazole, 2-methylimidazole, 2-phenylimidazole, and benzimidazole) that serve as protective and dispersing agents. Through a complexation reaction between Cu atoms, the imidazole compounds can form a protective film on the Cu nanoparticles to prevent the particles from rapidly oxidizing. We compared the effects of the four kinds of imidazole compounds on the oxidation resistance and sintering properties of Cu particles. The Cu particles prepared with benzimidazole could be stored in the air for 30 days without being oxidized. After sintering at 300 °C and 2 MPa, the joint of the particles could reach a shear strength of 32 MPa, which meets the requirements for microelectronic packaging. Full article

(This article belongs to the Special Issue Microelectronics Assembly and Packaging: Materials and Technologies)

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24 pages, 12664 KiB

Open AccessArticle

Electrical Performance Analysis of High-Speed Interconnection and Power Delivery Network (PDN) in Low-Loss Glass Substrate-Based Interposers

by Youngwoo Kim

Micromachines 2023, 14(10), 1880; https://doi.org/10.3390/mi14101880 - 29 Sep 2023

Viewed by 1433

Abstract

In this article, electrical performance analysis of high-speed interconnection and power delivery network (PDN) in low-loss glass substrate-based interposers is conducted considering signal integrity (SI) and power integrity (PI). The low-loss glass substrate is a superior alternative to silicon substrate in terms of high-speed signaling and fabrication yield. However, the low-loss of the substrate is vulnerable to power/ground noise in the PDN since the low-loss property of the substrate cannot suppress the noise naturally. In this article, an in-depth electrical performance analysis is conducted based on various measurements and simulations to fully benefit the advantages of the low-loss glass substrate. First, the fabrication process and test vehicles for the analysis are explained. Using the test vehicles, the electrical performance of the glass interposer’s high-speed interconnection is compared with those of silicon and organic interposers. The insertion loss, eye-diagrams, and signal bandwidths of three interposer channels are compared and analyzed based on electromagnetic (EM) and circuit simulations. Also, the electrical performance of the through glass via (TGV) channel is measured and compared with through silicon via (TSV) channel. The high-speed interconnection of the glass interposer showed better performance for most of the parameters which is more suitable for maintaining the SI. Even though the low-loss of the glass substrate ensured the SI, power/ground noise issues in the PDN must be analyzed and solved. In this article, various cases inducing the power/ground noise in the PDN are considered, simulated, and measured. To solve the issues, ground TGV design and electromagnetic bandgap (EBG) design are proposed for an efficient broadband suppression of the noise generated in the glass interposer PDN. Full article

(This article belongs to the Special Issue Microelectronics Assembly and Packaging: Materials and Technologies)

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15 pages, 5905 KiB

Open AccessArticle

Convolutional Neural Network Defect Detection Algorithm for Wire Bonding X-ray Images

by Daohua Zhan, Renbin Huang, Kunran Yi, Xiuding Yang, Zhuohao Shi, Ruinan Lin, Jian Lin and Han Wang

Micromachines 2023, 14(9), 1737; https://doi.org/10.3390/mi14091737 - 04 Sep 2023

Viewed by 1152

Abstract

To address the challenges of complex backgrounds, small defect sizes, and diverse defect types in defect detection of wire bonding X-ray images, this paper proposes a convolutional-neural-network-based defect detection method called YOLO-CSS. This method designs a novel feature extraction network that effectively captures semantic features from different gradient information. It utilizes a self-adaptive weighted multi-scale feature fusion module called SMA which adaptively weights the contribution of detection results based on different scales of feature maps. Simultaneously, skip connections are employed at the bottleneck of the network to ensure the integrity of feature information. Experimental results demonstrate that on the wire bonding X-ray defect image dataset, the proposed algorithm achieves mAP 0.5 and mAP 0.5–0.95 values of 97.3% and 72.1%, respectively, surpassing the YOLO series algorithms. It also exhibits certain advantages in terms of model size and detection speed, effectively balancing detection accuracy and speed. Full article

(This article belongs to the Special Issue Microelectronics Assembly and Packaging: Materials and Technologies)

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14 pages, 12872 KiB

Open AccessArticle

Effects of Process Parameters on Bond Properties of Ag-2.35Au-0.7Pd-0.2Pt-0.1Cu Alloy Wire

by Hongliang Zhou, Andong Chang, Junling Fan, Jun Cao, Yingchong Zhang, Bin An and Jie Xia

Micromachines 2023, 14(8), 1587; https://doi.org/10.3390/mi14081587 - 12 Aug 2023

Cited by 2 | Viewed by 962

Abstract

Bond properties were performed on Ag-2.35Au-0.7Pd-0.2Pt-0.1Cu alloy wire with a diameter of 25 µm under different process parameters. The effects of electrical flaming off (EFO) current and EFO time on the deformability of the free air ball (FAB) were investigated using scanning electron microscopy (SEM), as well as the effects of ultrasonic power and bonding force on the bond characteristic. The experimental results show that FAB grows from a preheated tip to a small ball, a regular ball, and finally to a golf ball with increasing either the EFO current or the EFO time, and the FAB presents an optimal shape at 25 mA and 650 μs. Moreover, a nonlinear relationship between FAB diameter and EFO time is obtained at an EFO current of 25 mA, which could be expressed by a cubic equation. Further, at a constant bonding force, as the ultrasonic power increased, the mashed ball diameter grew larger and larger, the capillary hole imprint became more and more obvious, and the tail width also increased, and vice versa. The optimal ultrasonic power and bonding force are 70 mW and 45 gf for ball bonding and 90 mW and 75 gf for wedge bonding, respectively. Finally, for all the bonded wire samples prepared under optimal process parameters, no ball and wedge bond lifts happened after the destructive pull test, and full intermetallic compound coverage with perfect morphology occurred on the bond pad after the ball shear test, which meant that the bonded wire samples had high bond strength and hence improved the reliability of microelectronic products. It provided technical support for the reliability research of Pt-containing Ag-based bonding alloy wires. Full article

(This article belongs to the Special Issue Microelectronics Assembly and Packaging: Materials and Technologies)

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22 pages, 52360 KiB

Open AccessArticle

An RDL Modeling and Thermo-Mechanical Simulation Method of 2.5D/3D Advanced Package Considering the Layout Impact Based on Machine Learning

by Xiaodong Wu, Zhizhen Wang, Shenglin Ma, Xianglong Chu, Chunlei Li, Wei Wang, Yufeng Jin and Daowei Wu

Micromachines 2023, 14(8), 1531; https://doi.org/10.3390/mi14081531 - 30 Jul 2023

Cited by 2 | Viewed by 1433

Abstract

The decreasing-width, increasing-aspect-ratio RDL presents significant challenges to the design for reliability (DFR) of an advanced package. Therefore, this paper proposes an ML-based RDL modeling and simulation method. In the method, RDL was divided into blocks and subdivided into pixels of metal percentage, and the RDL was digitalized as tensors. Then, an ANN-based surrogate model was built and trained using a subset of tensors to predict the equivalent material properties of each block. Lastly, all blocks were transformed into elements for simulations. For validation, line bending simulations were conducted on an RDL, with the reaction force as an accuracy indicator. The results show that neglecting layout impact caused critical errors as the substrate thinned. According to the method, the reaction force error was 2.81% and the layout impact could be accurately considered with 200 × 200 elements. For application, the TCT maximum temperature state simulation was conducted on a CPU chip. The simulation indicated that for an advanced package, the maximum stress was more likely to occur in RDL rather than in bumps; both RDL and bumps were critically impacted by layouts, and RDL stress was also impacted by vias/bumps. The proposed method precisely concerned layout impacts with few resources, presenting an opportunity for efficient improvement. Full article

(This article belongs to the Special Issue Microelectronics Assembly and Packaging: Materials and Technologies)

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15 pages, 4826 KiB

Open AccessArticle

Layout Dependence Stress Investigation in through Glass via Interposer Architecture Using a Submodeling Simulation Technique and a Factorial Design Approach

by Shih-Hung Wang, Wensyang Hsu, Yan-Yu Liou, Pei-Chen Huang and Chang-Chun Lee

Micromachines 2023, 14(8), 1506; https://doi.org/10.3390/mi14081506 - 27 Jul 2023

Viewed by 974

Abstract

The multi-chiplet technique is expected to be a promising solution to achieve high-density system integration with low power consumption and high usage ratio. This technique can be integrated with a glass interposer to accomplish a competitive low fabrication cost compared with the silicon-based interposer architecture. In this study, process-oriented stress simulation is performed by the element activation and deactivation technique in finite element analysis architecture. The submodeling technique is also utilized to mostly conquer the scale mismatch and difficulty in mesh gridding design. It is also used to analyze the thermomechanical responses of glass interposers with chiplet arrangements and capped epoxy molding compounds (EMC) during curing. A three-factor, three-level full factorial design is applied using the analysis of variance method to explore the significance of various structural design parameters for stress generation. Analytic results reveal that the maximum first principal stresses of 130.75 and 17.18 MPa are introduced on the sidewall of Cu-filled via and the bottom of the glass interposer, respectively. Moreover, the EMC thickness and through glass via pitch are the dominant factors in the adopted vehicle. They significantly influence the stress magnitude during heating and cooling. Full article

(This article belongs to the Special Issue Microelectronics Assembly and Packaging: Materials and Technologies)

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15 pages, 7485 KiB

Open AccessArticle

ATNet: A Defect Detection Framework for X-ray Images of DIP Chip Lead Bonding

by Renbin Huang, Daohua Zhan, Xiuding Yang, Bei Zhou, Linjun Tang, Nian Cai, Han Wang and Baojun Qiu

Micromachines 2023, 14(7), 1375; https://doi.org/10.3390/mi14071375 - 05 Jul 2023

Viewed by 1106

Abstract

In order to improve the production quality and qualification rate of chips, X-ray nondestructive imaging technology has been widely used in the detection of chip defects, which represents an important part of the quality inspection of products after packaging. However, the current traditional defect detection algorithm cannot meet the demands of high accuracy, fast speed, and real-time chip defect detection in industrial production. Therefore, this paper proposes a new multi-scale feature fusion module (ATSPPF) based on convolutional neural networks, which can more fully extract semantic information at different scales. In addition, based on this module, we design a deep learning model (ATNet) for detecting lead defects in chips. The experimental results show that at 8.2 giga floating point operations (GFLOPs) and 146 frames per second (FPS), mAP_0.5 and mAP_0.5–0.95 can achieve an average accuracy of 99.4% and 69.3%, respectively, while the detection speed is faster than the baseline yolov5s by nearly 50%. Full article

(This article belongs to the Special Issue Microelectronics Assembly and Packaging: Materials and Technologies)

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17 pages, 4967 KiB

Open AccessArticle

Development of ANN-Based Warpage Prediction Model for FCCSP via Subdomain Sampling and Taguchi Hyperparameter Optimization

by Hsien-Chie Cheng, Chia-Lin Ma and Yang-Lun Liu

Micromachines 2023, 14(7), 1325; https://doi.org/10.3390/mi14071325 - 28 Jun 2023

Cited by 2 | Viewed by 1153

Abstract

This study aims to establish an accurate prediction model using artificial neural networks (ANNs) to effectively and efficiently predict the process-induced warpage of a flip-chip chip-scale package (FCCSP). To enhance model performance, a novel subdomain-based sampling strategy and Taguchi hyperparameter optimization are proposed in the ANN algorithm. To simulate the warpage behavior the FCCSP during fabrication, a process modeling approach is proposed, where the viscoelastic behavior of the epoxy molding compound is included, in which the viscoelastic properties are determined using dynamic mechanical measurement. In addition, the temperature-dependent thermal-mechanical properties of the materials in the FCCSP are assessed through thermal-mechanical analysis and dynamic mechanical analysis. The modeled warpage results are verified by the warpage measurement. Next, warpage parametric analysis is performed to identify the key factors most affecting warpage behavior for use in the construction of the warpage prediction model. Moreover, the advantages of the proposed sampling and hyperparameter tuning approaches are proved by comparing with other existing models, and the validity of the developed ANN-based deep learning warpage prediction model is demonstrated through a validation dataset. Full article

(This article belongs to the Special Issue Microelectronics Assembly and Packaging: Materials and Technologies)

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11 pages, 5415 KiB

Open AccessArticle

Facile Preparation of Monodisperse Cu@Ag Core–Shell Nanoparticles for Conductive Ink in Printing Electronics

by Gang Li, Xuecheng Yu, Ruoyu Zhang, Qionglin Ouyang, Rong Sun, Liqiang Cao and Pengli Zhu

Micromachines 2023, 14(7), 1318; https://doi.org/10.3390/mi14071318 - 27 Jun 2023

Cited by 1 | Viewed by 1045

Abstract

Copper-based nanoinks are emerging as promising low-cost alternatives to widely used silver nanoinks in electronic printing. However, the spontaneous oxidation of copper under ambient conditions poses significant challenges to its broader application. To address this issue, this paper presents an economical, large-scale, and environmentally friendly method for fabricating Cu@Ag nanoparticles (Cu@Ag NPs). The as-prepared nanoparticles exhibit a narrow size distribution of approximately 100 nm and can withstand ambient exposure for at least 60 days without significant oxidation. The Cu@Ag-based ink, with a 60 wt% loading, was screen-printed onto a flexible polyimide substrate and subsequently heat-treated at 290 °C for 15 minutes under a nitrogen atmosphere. The sintered pattern displayed a low electrical resistivity of 25.5 μΩ·cm (approximately 15 times the resistivity of bulk copper) along with excellent reliability and mechanical fatigue strength. The innovative Cu@Ag NPs fabrication method holds considerable potential for advancing large-scale applications of copper-based inks in flexible electronics. Full article

(This article belongs to the Special Issue Microelectronics Assembly and Packaging: Materials and Technologies)

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18 pages, 5553 KiB

Open AccessArticle

A Lightweight Method for Detecting IC Wire Bonding Defects in X-ray Images

by Daohua Zhan, Jian Lin, Xiuding Yang, Renbin Huang, Kunran Yi, Maoling Liu, Hehui Zheng, Jingang Xiong, Nian Cai, Han Wang and Baojun Qiu

Micromachines 2023, 14(6), 1119; https://doi.org/10.3390/mi14061119 - 26 May 2023

Cited by 3 | Viewed by 1507

Abstract

Integrated circuit (IC) X-ray wire bonding image inspections are crucial for ensuring the quality of packaged products. However, detecting defects in IC chips can be challenging due to the slow defect detection speed and the high energy consumption of the available models. In this paper, we propose a new convolutional neural network (CNN)-based framework for detecting wire bonding defects in IC chip images. This framework incorporates a Spatial Convolution Attention (SCA) module to integrate multi-scale features and assign adaptive weights to each feature source. We also designed a lightweight network, called the Light and Mobile Network (LMNet), using the SCA module to enhance the framework’s practicality in the industry. The experimental results demonstrate that the LMNet achieves a satisfactory balance between performance and consumption. Specifically, the network achieved a mean average precision (

m A P_{50}

) of 99.2, with 1.5 giga floating-point operations (GFLOPs) and 108.7 frames per second (FPS), in wire bonding defect detection. Full article

(This article belongs to the Special Issue Microelectronics Assembly and Packaging: Materials and Technologies)

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Review

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29 pages, 17283 KiB

Open AccessReview

Research Progress of Palladium-Plated Copper Bonding Wire in Microelectronic Packaging

by Yuemin Zhang, Haiyun Guo, Jun Cao, Xuefeng Wu, Hewei Jia and Andong Chang

Micromachines 2023, 14(8), 1538; https://doi.org/10.3390/mi14081538 - 31 Jul 2023

Viewed by 1498

Abstract

Wire-bonding technology is the most commonly used chip interconnection technology in microelectronic packaging. Metal bonding wire is the key material for wire bonding and plays an important role in the reliability of electronic devices. In recent years, palladium-plated copper (PdCu) bonding wire has been widely used because of its low cost, good electrical and thermal conductivity, the fact that it is not easy to oxidize, and its high reliability. Therefore, it is necessary to review its research progress. In this paper, the preparation and application of palladium-plated copper bonding wire are reviewed. Firstly, the preparation methods of electroplating, electroless plating, and direct plating are introduced. Secondly, the factors affecting the distribution of Pd in free air balls and bonding interfaces, the effect of Pd on the formation and growth of intermetallic compounds in PdCu wire, stitch bond, and reliability of PdCu wire are summarized and analyzed in the application process. Finally, its development prospect is prospected. Hopefully, this review can help readers to have a comprehensive understanding of the preparation and application of palladium-plated copper bonding wires, and can accelerate the promotion of its application in more fields in the future. Full article

(This article belongs to the Special Issue Microelectronics Assembly and Packaging: Materials and Technologies)

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