Effect of thermal aging on interfacial behaviour of copper ball bonds

Thermosonic copper ball bonding is an interconnection technology that serves as a viable and cost-saving alternative to gold ball bonding. However, the reliability of copper bonds remains to be ascertained. Intermetallic compounds (IMCs) and possible voids and cracks may grow and propagate at the interface of bonds during their service. The proper IMCs formation is beneficial to bonding strength but an excessive growth of IMCs, voids and cracks can induce a mechanical failure and increase a contact resistance. In this study, a 99.99% copper wire with diameter 50.4 mum was bonded to a Al-1%Si-0.5%Cu metallisation pad by thermosonic bonding. Scanning electron microscopy, energy dispersive X-ray spectrometry, dual focused ion bean and transmission electron microscopy (TEM) were used to investigate the interfacial evolution of such formed joints during the thermal ageing, and kinetics of Cu-Al IMCs growth was established. The results showed no IMCs at the initial bonded Cu/Al interface. To study the Cu-Al IMCs growth, the samples were thermally aged for different times at a temperature from 200 degC to 300 degC to accelerate interfacial evolution. The growth of Cu-Al IMCs followed the parabolic law as a function of aging time at a certain aging temperature, and it is more sensitive to temperature compared to time. The activation energy of Cu-Al IMC growth was obtained from the Arrhenius plot. Voids and cracks, which are commonly present in gold ball bonds due to thermal aging, were not observed in copper ball bonds even after aging at 200 degC for 2900 hours. Finally, the structure of Cu-Al IMCs was confirmed to be Cu9Al4 by selected area electron diffraction with TEM

Effects of process parameters on bondability in thermosonic copper ball bonding

Thermosonic copper ball bonding is an absorbing interconnection technology that serves as a viable and cost saving alternative to gold ball bonding. Its excellent mechanical and electrical characteristics make copper ball bonding attractive for high-speed, power devices and fine-pitch applications. However, copper is easily oxidized and harder than gold, which causes some critical process problems in connection with bondability. In this study, a 50 mum copper wire with purity of 99.99% was bonded on aluminum metallization with thickness 3 mum using an ASM angle 60 automatic thermosonic ball/wedge bonder. Experimental studies of copper free air balls (FABs) formation and bonding process were conducted to establish the bonding mechanism and to explain the effects of process parameters on bondability. A micro-slipping model was proposed to account for the effects of the ultrasonic power and bonding force on bondability. It was found that the bondability was determined by a slip area at the bonding interface. The occurrence of bonding only at the periphery of the contact area between FAB and aluminum metallization was attributed to partial slips at the bonding interface. Variation in the ultrasonic power and bonding force that lead to different stick-slip modes, can effect bondability in the ultrasonic bonding process. It is important to set a proper bonding time to achieve interatomic bonding without causing fatigue rupture of microjoints. It was also found that preheating of the chip to a certain temperature can improve bondability

Vektor Malaria Baru di Kabupaten Kotabaru, Provinsi Kalimantan Selatan, Indonesia

Nyamuk Anopheles merupakan vektor dari Malaria. Dari sekitar 400 spesies nyamuk Anopheles telah ditemukan 67 spesies dapat menularkan malaria dan 24 diantaranya ditemukan di Indonesia. Kabupaten Kotabaru merupakan kabupaten endemis malaria di Kalimantan Selatan. Data mengenai spesies vektor malaria spesifik pada suatu daerah sangat berperan penting sebagai salah satu bahan rekomendasi bagi tindak lanjut kebijakan pengendalian malaria. Penelitian bertujuan untuk mengetahui data vektor malaria di Kabupaten Kotabaru melalui uji PCR. Penelitian deskriptif dengan desain cross sectional. Penangkapan nyamuk dilakukan di Desa Siayuh Trans dan Magalau Hulu, tambang emas Kura-Kura dan Desa Muara Uri dengan metode penangkapan UOL, UOD, dinding dan kandang. Uji PCR dilaksanakan di laboratorium biomolekuler BBPPVRP Salatiga pada bulan Februari-April 2015. Hasil penangkapan nyamuk didapatkan 345 ekor nyamuk Anopheles yang terdiri dari 9 spesies: An. barbirostris, An. tesselatus, An. balabacensis, An. vagus, An. hyrcanus group, An. peditaeniatus, An. kochi, An. flavirostris, An. umbrosus. Seluruh nyamuk Anopheles yang didapatkan dibuat 56 pool sampel Anopheles sp untuk diuji PCR yang telah diklasifikasikan berdasarkan spesies, tanggal dan metode penangkapan. Hasil PCR terindentifikasi 3 spesies vektor malaria di Desa Siayuh Trans yaitu An. vagus, An. peditaeniatus dan An. tesselatus yang merupakan vektor malaria baru di Propinsi Kalimantan Selatan

TEM Microstructural Analysis of As-bonded Copper Ball Bonds on Aluminum Metallization

In this study, the nano-scale interfacial details of ultrasonic copper ball bonding to an aluminum metallization in the as-bonded states were investigated using high resolution scanning/transmission electron microscopy with energy dispersive spectroscopy. Our results showed that ultrasonic vibration swept aluminum oxide and copper oxide in some regions of contacting surface, where an approximate 20 nm Cu-Al intermetallics (i.e. CuAl2) formed. In the regions where oxide remained, aluminum oxide layer connected with copper oxides layer. No nano-level voids or gaps were observed at the central area of the interface, including the regions with oxide. Calculation of interfacial temperature showed that the ultrasonic vibration increased the flash temperature up to 465degC which was believed to improve the interdiffusion for the formation of Cu-Al intermetallics

DataSheet_2_Single-Cell RNA Sequencing of Peripheral Blood Reveals Immune Cell Signatures in Alzheimer’s Disease.xlsx

The peripheral immune system is thought to affect the pathology of the central nervous system in Alzheimer’s disease (AD). However, current knowledge is inadequate for understanding the characteristics of peripheral immune cells in AD. This study aimed to explore the molecular basis of peripheral immune cells and the features of adaptive immune repertoire at a single cell level. We profiled 36,849 peripheral blood mononuclear cells from AD patients with amyloid-positive status and normal controls with amyloid-negative status by 5’ single-cell transcriptome and immune repertoire sequencing using the cell ranger standard analysis procedure. We revealed five immune cell subsets: CD4+ T cells, CD8+ T cells, B cells, natural killer cells, and monocytes–macrophages cells, and disentangled the characteristic alterations of cell subset proportion and gene expression patterns in AD. Thirty-one cell type-specific key genes, comprising abundant human leukocyte antigen genes, and multiple immune-related pathways were identified by protein–protein interaction network and pathway enrichment analysis. We also found high-frequency amplification clonotypes in T and B cells and decreased diversity in T cells in AD. As clone amplification suggested the activation of an adaptive immune response against specific antigens, we speculated that the peripheral adaptive immune response, especially mediated by T cells, may have a role in the pathogenesis of AD. This finding may also contribute to further research regarding disease mechanism and the development of immune-related biomarkers or therapy.</p

Amorphous MoO₂/C Nanospheres–Porous Graphene Composites for Pseudocapacitive Li Storage

Amorphous MoO2 nanostructures are regarded as promising anode materials for lithium-ion batteries (LIBs) due to their unusually high capacity. However, designing an amorphous MoO2 nanostructure with satisfactory performance still remains greatly challenging owing to the poor conductivity and unstable structure. In this study, a hierarchically porous composite composed of amorphous MoO2/C nanospheres and interconnected graphene networks (MoO2/C-rGO) was fabricated by a convenient route. Thanks to the oxygen-deficient amorphous nanostructure, open diffusion channels, and continuous conductive networks, the electrochemical performance of the composite has been significantly enhanced. Specifically, it delivers an extraordinary initial discharge capacity of 1328 mA h g–1 at 0.1 A g–1, a high initial Coulombic efficiency (CE) of 82.6%, an impressive rate capability of 444 mA h g–1 at 8.0 A g–1, and a good cyclability with 642 mA h g–1 after 500 cycles at 1.0 A g–1. Electrochemical analysis indicates that the Li storage of MoO2/C-rGO is dominated by a pseudocapacitive mechanism, which allows rapid insertion/extraction of Li+ without damaging the structure of the electrode, thus achieving structural and electrical integrity

DataSheet_4_Single-Cell RNA Sequencing of Peripheral Blood Reveals Immune Cell Signatures in Alzheimer’s Disease.docx

The peripheral immune system is thought to affect the pathology of the central nervous system in Alzheimer’s disease (AD). However, current knowledge is inadequate for understanding the characteristics of peripheral immune cells in AD. This study aimed to explore the molecular basis of peripheral immune cells and the features of adaptive immune repertoire at a single cell level. We profiled 36,849 peripheral blood mononuclear cells from AD patients with amyloid-positive status and normal controls with amyloid-negative status by 5’ single-cell transcriptome and immune repertoire sequencing using the cell ranger standard analysis procedure. We revealed five immune cell subsets: CD4+ T cells, CD8+ T cells, B cells, natural killer cells, and monocytes–macrophages cells, and disentangled the characteristic alterations of cell subset proportion and gene expression patterns in AD. Thirty-one cell type-specific key genes, comprising abundant human leukocyte antigen genes, and multiple immune-related pathways were identified by protein–protein interaction network and pathway enrichment analysis. We also found high-frequency amplification clonotypes in T and B cells and decreased diversity in T cells in AD. As clone amplification suggested the activation of an adaptive immune response against specific antigens, we speculated that the peripheral adaptive immune response, especially mediated by T cells, may have a role in the pathogenesis of AD. This finding may also contribute to further research regarding disease mechanism and the development of immune-related biomarkers or therapy.</p

DataSheet_1_Single-Cell RNA Sequencing of Peripheral Blood Reveals Immune Cell Signatures in Alzheimer’s Disease.xlsx

The peripheral immune system is thought to affect the pathology of the central nervous system in Alzheimer’s disease (AD). However, current knowledge is inadequate for understanding the characteristics of peripheral immune cells in AD. This study aimed to explore the molecular basis of peripheral immune cells and the features of adaptive immune repertoire at a single cell level. We profiled 36,849 peripheral blood mononuclear cells from AD patients with amyloid-positive status and normal controls with amyloid-negative status by 5’ single-cell transcriptome and immune repertoire sequencing using the cell ranger standard analysis procedure. We revealed five immune cell subsets: CD4+ T cells, CD8+ T cells, B cells, natural killer cells, and monocytes–macrophages cells, and disentangled the characteristic alterations of cell subset proportion and gene expression patterns in AD. Thirty-one cell type-specific key genes, comprising abundant human leukocyte antigen genes, and multiple immune-related pathways were identified by protein–protein interaction network and pathway enrichment analysis. We also found high-frequency amplification clonotypes in T and B cells and decreased diversity in T cells in AD. As clone amplification suggested the activation of an adaptive immune response against specific antigens, we speculated that the peripheral adaptive immune response, especially mediated by T cells, may have a role in the pathogenesis of AD. This finding may also contribute to further research regarding disease mechanism and the development of immune-related biomarkers or therapy.</p

DataSheet_3_Single-Cell RNA Sequencing of Peripheral Blood Reveals Immune Cell Signatures in Alzheimer’s Disease.xlsx

The peripheral immune system is thought to affect the pathology of the central nervous system in Alzheimer’s disease (AD). However, current knowledge is inadequate for understanding the characteristics of peripheral immune cells in AD. This study aimed to explore the molecular basis of peripheral immune cells and the features of adaptive immune repertoire at a single cell level. We profiled 36,849 peripheral blood mononuclear cells from AD patients with amyloid-positive status and normal controls with amyloid-negative status by 5’ single-cell transcriptome and immune repertoire sequencing using the cell ranger standard analysis procedure. We revealed five immune cell subsets: CD4+ T cells, CD8+ T cells, B cells, natural killer cells, and monocytes–macrophages cells, and disentangled the characteristic alterations of cell subset proportion and gene expression patterns in AD. Thirty-one cell type-specific key genes, comprising abundant human leukocyte antigen genes, and multiple immune-related pathways were identified by protein–protein interaction network and pathway enrichment analysis. We also found high-frequency amplification clonotypes in T and B cells and decreased diversity in T cells in AD. As clone amplification suggested the activation of an adaptive immune response against specific antigens, we speculated that the peripheral adaptive immune response, especially mediated by T cells, may have a role in the pathogenesis of AD. This finding may also contribute to further research regarding disease mechanism and the development of immune-related biomarkers or therapy.</p

Resolving the Reaction Mechanism for Oxidative Hydration of Ethylene toward Ethylene Glycol by Titanosilicate Catalysts

Due to the complex internal structure of titanium silicalite-1, the reaction mechanism for oxidative hydration of ethylene toward ethylene glycol on the titanium silicalite-1 (TS-1) catalyst is still disputable and inconclusive. In this work, density functional theory calculations, microkinetic modeling, and experiments are combined to provide unique insights into the reaction mechanism. With consideration of perfect titanium sites (including isolated and dinuclear titanium sites) and hydrolyzed titanium sites, the results demonstrate that oxidative hydration of ethylene prefers a catalysis mechanism completed by the coupling of two types of active centers, where the isolated titanium site participates in ethylene epoxidation and the hydrolyzed titanium site is responsible for the hydration of ethylene oxide. The ethylene glycol generation rate, reaction order, and apparent activation energy calculated by microkinetic modeling are highly consistent with our experimental kinetics. This study provides a decisive description of the reaction mechanism for oxidative hydration of ethylene over TS-1 catalysts, which may enable further optimization of TS-1 by targeted modification on specific active centers