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Abstract Low-temperature transient liquid phase (TLP) bonding is a promising joining technology for high-temperature electronic devices packaging. However, the effect of thermal aging on the joint microstructure and performance has been rarely studied so far. In this paper, the relationship between microstructural evolution and mechanical property was developed for the Cu/Sn/Ag TLP-bonded joint during 350 °C aging. Experimental results show that an interfacial reaction occurs between the intermetallic compounds (IMCs) of Cu 3 Sn and Ag 3 Sn, which induces that a great amount of Cu 3 Sn particles or wedges embed into the Ag-Sn phase layer. The reaction process is controlled by a volume diffusion of Cu elements from the Cu substrate, and capable of promoting the transformation from Ag 3 Sn into Ag(Sn) solid solution. Cu 41 Sn 11 phase can be formed at the expense of Cu 3 Sn and Cu, of which transformation process is completely achieved after aging for 480 h, and the Cu(Sn) solid solution intimately contacts with the opposite Ag(Sn) solid solution in many areas after aging for 960 h. The joint mechanical property initially declines due to the formation of Cu 41 Sn 11 phase and Cu-Sn IMCs grain coarsening, and then increases because of the complete depletion of Cu 3 Sn and substantial precipitation of Cu(Sn) solid solution. After aging for nearly 1000 h, the joint still maintains a high shear strength of >40 MPa, indicating an excellent thermal reliability. Highlights • The thermal reliability of the Cu/Sn/Ag TLP-bonded joint was investigated through high-temperature storage. • A diffusion reaction occurred at the interface between Cu 3 Sn and Ag 3 Sn during thermal aging. • The mechanism of the Cu 3 Sn/Ag 3 Sn interfacial reaction was investigated from thermodynamics and kinetics. [ABSTRACT FROM AUTHOR]

The life expectancy of a transformer is closely related to the ageing state of its paper insulation. This paper presents novel markers for ageing characterization of paper insulation in oil-filled transformers based on the dispersion staining colors of cellulose fibres. Accelerated thermal ageing experiments were performed for oil-paper specimens at 120 and 130 °C to obtain aged oil-paper samples of different ageing degrees. The average degree of polymerization (DP), crystallinity index, and refractive index of insulation paper were measured; the experimental results show that an increase in refractive index of insulation paper was observed with the increase of ageing degree. Meanwhile, the dispersion staining colors of cellulose fibres in oil were observed using dispersion staining method; the experimental results show that the refractive index of cellulose fibres detached from insulation paper increases with the increment of ageing degree of insulation paper. Finally, two ageing markers—that is, the primary color ratio-based ratio of blue to red and the primary color ratio-based Mahalanobis distance were presented. Their relationship with DP and ageing time of insulation paper were obtained, and were compared with the corresponding relationship with 2-furaldehyde (2-FAL) and carbon oxides. The proposed ageing markers demonstrate an advantage over 2-FAL and carbon oxides and show potential in ageing state evaluation and residual life prediction of paper insulation in transformers. [ABSTRACT FROM AUTHOR]

By shrinking the transistors' dimensions, some aging phenomena effects that were negligible in previous technologies have become the most serious reliability threats. The most important aging process is Bias Temperature Instability (BTI). This phenomenon dissociates the chemical bonds between the silica lattice and hydrogen at the interface between the gate insulator and the transistor channel. The SRAM structures are vulnerable to BTI due to the long stress time on the transistors of this structure during normal system operations. Regardless of the stored values on the SRAM cells, the cross-coupled structure of this cell leads to continuous stress on at least two transistors of the cell at a given time. To mitigate the aging of the SRAM structures, like cache memories, there are many aging avoidance and aging mitigation techniques in the literature on this topic. However, the overheads or the efficiency thereof are not tolerable in many cases. This paper proposes an aging mitigation mechanism for cache memories by exchanging the values that are periodically stored in data and instruction caches. The results show that while the area and performance overheads of the proposed mechanism are negligible (less than 1%), the average stress time on the cache memories decreases by 2.39×, which prolongs the Mean Time to Failure (MTTF) of the memory structure by 1.91×. [ABSTRACT FROM AUTHOR]

The microstructure evolution in the abrasion-induced altered surface layer (ASL) during long-term natural aging and its effect on localized corrosion in AA7055 were studied using scanning transmission electron microscopy and potentiodynamic polarization measurements. Surface abrasion of AA7055 in the peak-aged (T6) temper creates an ASL that is around 300 nm thick and contains ultrafine subgrains. Cu-rich particles including Al 2 Cu phase were also found to precipitate at the extreme surface and at subgrain boundaries in the ASL, as well as in the underlying bulk substrate close to the ASL on AA7055-T6. These large Cu-rich particles grew during 12 months of natural aging following surface abrasion, then stopped growing. Some of them then dissolved during the subsequent 48 months of natural aging. Zn solute enriched at the subgrain boundaries in the ASL, and was depleted in the matrix solid solution of the ASL after 60 months of natural aging, but depletion of Cu was not evident on AA7055-T6. The breakdown potentials of the ASL were 50 mV–80 mV higher for the abraded and naturally aged AA7055-T6 samples compared to the as-abraded condition, indicating that long-term natural aging improved the corrosion resistance of the ASL. The depletion of Zn in the matrix of the ASL and the increased matrix Cu content due to the dissolution of large Cu-rich particles might be responsible for the increase in breakdown potential of the ASL. [ABSTRACT FROM AUTHOR]

This research was planned to clarify the relationship between natural ageing and accelerated ageing of paper using naturally aged paper. First, samples of paper which had deteriorated over time for 130 to 80 years were artificially aged at 80°C, 65% RH, and their physical and chemical changes were investigated. Oxalic acid contained in the samples before accelerated ageing increased, while glycolic acid showed a tendency to decrease. This means that accelerated ageing test did not simulate the chemical processes occurring during natural ageing in a straight forward manner. On the other hand, paper in which many organic acids had accumulated by natural ageing showed larger degradation rate indicators of tear index and burst index i.e. initial degradation rate constant divided by initial tear index or initial burst index before accelerated ageing and discolouration rate. That of values of the degradation rate indicators of tear index and burst index and the discolouration rate showed good correlation with the number of cellulose chain breaks. However, the number of cellulose chain breaks is not simply correlated with the concentration of hydrogen ion which is an index of the acidic hydrolysis of paper. Oxidation contributes to the rate of cellulose chain breaks. [ABSTRACT FROM AUTHOR]

The article discusses a treatment for paper made from wood-pulp being stored in library and archive collections intended to slow deterioration. It comments on the process and benefits of the process, including removing soluble acidic products, preventing decay caused by oxidization, and increasing the mechanical strength of the paper itself. The authors note the historical and social importance of preserving historic documents.

The article discusses analysis of the long term efficacy of mass deacidification of library books as it relates to alkaline reserve. It comments on the difficulties of accurately determining alkaline reserve and identifies book age and specific deacidification processes and the main factors influencing treatment efficacy. Other topics include the Papersave process to determine alkaline reserve, long term stability of cellulose in paper, and assessing alkaline reserve through titration.

The article presents a study on the rolling test method which is used to evaluate paper deterioration. The study analyzes the correlation between the rolling test and conventional mechanical measurements using paper samples of varying levels of degradation, which are rolled using cylinders of different diameters. The results reveal that samples from the second half of the 1800s are less flexible than samples from other periods, and that groundwood pulp is a potential cause of the deterioration.

Abstract: The effects of air-exposure-time and time-dependency (ageing) on the Pb/p-Si Schottky diodes have been investigated by room temperature I–V and C–V measurements. The barrier height (BH) values between I–V and C–V measurements of the air-exposed samples have been found to be higher than those of the reference diode, and associated with the passivation of the intrinsic surface states on the cleaned Si surface. The ideality factor and the BH values of the air-exposed samples have reached to saturation after ten days air-exposure and the case has been interpreted as the saturation of the oxide layer thickness. The ageing has increased the ideality factors while decreasing the BHs of the samples with increasing ageing time. Both of the parameters have reached to the saturation at 720h after metal deposition. The carrier concentrations of the air-exposed samples have been considerably lower than that of the reference diode and decreased with increasing exposure-time to air and ageing. This result has been attributed to the passivation of the acceptors by hydrogen atoms diffused into the semiconductor and so the surface Fermi level unpinning. The BH values determined from C–V measurements have reached to equilibrium BH values at 720h after metal deposition as determined from I–V measurements. [ABSTRACT FROM AUTHOR]

Purpose - This paper aims to provide a theoretical guide for preserving ancient books in China. Design/methodology/approach - The paper reviews the history of the damage and preservation of ancient books in China, and analyzes the value attributes of ancient books: archaeological value, historical value and artistic value. Findings - The paper proposes a preservation framework for Chinese ancient books. This framework is composed of three layers. The foundation layer is to preserve the physical entity of ancient books so that the archaeological values are preserved. The middle layer is to preserve the intellectual content of ancient books so that the values for historical research are preserved. The top layer is mainly about preserving the productions process of the artistic format of ancient books, so that not only the static artistic formats are preserved, the techniques and procedures to produce the artistic format are preserved as well. Originality/value - The paper presents a framework that connects the value attributes of ancient books and the strategies to preserve those values, systematizes them and presents them as a whole. The framework can be used to justify government policies and help identify pitfalls in the preservation strategies for ancient books. [ABSTRACT FROM AUTHOR]

New forms of knowledge production in the so-called "information age" have led Archival Science to renew its theoretical and methodological corpus so it can be adapted to this new reality. In this way, new approaches for archival knowledge organization have emerged in Canada since the late 80's, emphasizing here Integrated Archival Science, which has established a rich dialogue with Information Science and Documentation, when defined its object of study as organic information. Therefore, the purpose of this study is to characterize and analyze Integrated Archival Science and its object, as a starting point for analyzing the relation between Archival Science and Information Science from the dialogue established through the concept of recorded information. [ABSTRACT FROM AUTHOR]

The article presents a study that evaluates the efficiency of calcium phytate and calcium hydrogen carbonate treatment in stabilizing cellulose degradation caused by iron gall ink on molecular level. It cites that combination of calcium phytate, a chelating agent, and calcium hydrogen carbonate, a deacidification agent, was applied in three types of paper including the historic paper, Whatman filter paper and model paper. An ageing process was performed after the phytate treatment to test its long stability. It notes that an efficient treatment can suppress the formation of new carbonyls groups and cleavage of the cellulose chain. It concludes that the treatment is most efficient on inked historic rag paper as no degradation is observed after the application of the treatment.

The article discusses librarians' responsibility to discard irreparable library books, a process which the author refers to as weeding. He uses wit and humor to discuss criteria for removing a book from the library's collection, which include old spine glue, date of the last checkout, and dustiness. He explains differences in librarians' approaches to the process, including efficiency, book repair, and the pros and cons of discarding books. Library budgets and replacing discarded books are also discussed.

Editorial. Cautions that the majority of books and periodicals printed on wood-pulp paper before 1920 are in serious physical jeopardy, and looks at the impact that could have on art historians and others interested in the illustrations printed on acid paper in those books. Comparison to book-burning by Nazis in the 1930s; Why black-and-white microfilm isn't acceptable substitute for illustrations; Possible solutions suggested by the Task Force on Text and Imaging; More.