Integrating Electronics to Textiles by Ultrasonic Welding for Cable-Driven Applications for Smart Textiles

The connection between flexible textiles and stiff electronic components has always been structurally weak and a limiting factor in the establishment of smart textiles in our everyday life. This paper focuses on the formation of reliable connections between conductive textiles and conventional litz wires using ultrasonic welding. The paper offers a promising approach to solving this problem. The electrical and mechanical performance of the samples were investigated after 15 and 30 wash-and-dry cycles in a laundry machine. Here the contact resistances and their peeling strength were measured. Furthermore, their connection properties were analysed in microsections. The resistance of the joints increased more than 300%, because the silver-coated wires suffered under the laundry cycles. Meanwhile, the mechanical strength during the peeling test decreased by only about 20% after 15 cycles and remained the same after 30 cycles. The good results obtained in this study suggest that ultrasonic welding offers a useful approach to the connection of textile electronics to conductive wires and to the manufacture of smart textiles.

Overmoulding of Additively Manufactured Titanium Inserts Using Polyoxymethylene (POM)—Evaluation of Bond Quality as a Function of Process Parameters

Due to their process-induced porous surfaces, additively manufactured structures are not optimized for applications in which friction is a key factor. To improve the frictional properties of additively manufactured titanium inserts of various thicknesses, two tribologically optimized POM materials, which differ in terms of filler composition and contents, were used to overmould the inserts. The titanium inserts were manufactured in two different building directions, resulting in a variation in surface roughness. The main challenge with respect to overmoulding is to maintain an even, thin plastic layer on the titanium insert. In order to evaluate the adhesion between plastic and metal, the interface is examined by optical microscopy and assessment of the peeling resistance. The peeling test shows that the overmoulded titanium inserts with a higher surface roughness are characterized by a higher peeling resistance. It is further revealed that the POM material with a special filler concept shows superior peeling resistance.

Manufacturing of three-layered sandwich composite of AA1050/LZ91/AA1050 using cold roll bonding process

In this paper, for the first time, dual-phase Mg-Li alloy is used to produce a three-layered Al/Mg/Al composite with the use of the cold roll bonding process. The low density and high ductility are known as the essential advantages of the Mg-Li alloys, while a couple of important problems should be taken into account, namely low corrosion resistance and low strength. It has been tried to deal with the mentioned problems by performing cold work and cover the Mg sheet with the Al similar plates. To investigate the Mg-Al layers bonding quality, mechanical properties and microstructure were examined for different thicknesses reduction ratio. The peeling test results showed that with increasing rolling pressure, the size and number of cracks on the brittle surfaces due to brushing, surface expansion, and metal extrusion between the cracks were improved by rising the reduction thickness ratio, bond strength enhanced, sharply. The UTS of 33.33% thickness reduction three-layered Al/Mg sample was obtained 186.5 MPa, which was more than 2.1 and 1.3 times higher than the initial Al1050 and MgLZ91 samples, respectively. However, because of increasing the amount of thickness reduction, roll-bonded layers’ quality, the tensile strength of the composite, and the microhardness of both layers increased. Furthermore, the elongation has reduced, and the maximum ultimate tensile strength and microhardness were achieved at 66.67% thickness reduction.

Multi-Analytical Characterization of Corvins’ Castle—Deserted Tower. Construction Materials and Conservation Tests

The aim of this paper is to analyze the construction materials (mortars) of an architectural monument (Deserted Tower (Lilly Tower) from Corvins’ Castle, Romania). The mortars were characterized following a multidisciplinary approach, combining macroscopic observation with petrographic microscopy, mineralogical analysis (X-ray diffraction) and elemental analysis (X-ray fluorescence), hydric properties, and color of representative samples of the monument. The results revealed the use of gypsum mortars (produced by lumps with higher Fe content), with minor concentrations of crystalline dolomites of the Southern Carpathians, calcite, and quartz. The materials’ effective porosity and their water absorption capacity were high. A possible solution to consolidate the damaged area with some consolidation products (hydroxyapatite carbonate and its derivatives with Ag and Sr) was investigated, too. The interactions between the mortar’s specimens and the effectiveness of the consolidation treatments were evaluated by physico-chemical analyses (molecular structure by X-ray powder diffraction (XRPD), wavelength dispersive X-ray fluorescence (WDXRF), dynamic light scattering (DLS)), morphological characterization by microscopic techniques as SEM-EDS, TEM, and physical and mechanical investigations (peeling test and compressive strength). Results were drawn based on historical, in situ observations, and analytical data, and put into evidence the composition, high weathering degree, and the possibility to surface consolidate with Sr-CHAp.

Archaeological chert artifacts from Atapuerca sites (Burgos, Spain): Characterization, causes of decay and selection of compatible consolidating products

Chert tools from Galería and Gran Dolina Caves, located in the Sierra de Atapuerca site complex (Burgos, Spain), were characterized (macro-visual inspection, mineralogical phases, degree of crystallinity, soluble salts, surface morphology and optical surface roughness) and compared to chert samples collected from the surrounding Atapuerca mountain range. The chert tools were studied to determine their causes of decay and for selecting the most compatible consolidation treatments. It was found that samples solely containing quartz were not significantly altered and required little conservation treatment compared to those that contained quartz and moganite, which were more weathered and powdery, requiring consolidation. The efficacy of the consolidating products traditionally used by conservators (acrylic resin and ethyl silicate) to preserve these chert remains, together with novel nanoparticle-based products (SiO2 and a mixture of SiO2 and Ca(OH)2 nanoparticles) were assessed in this study. Changes produced by these consolidating products in the physical (surface morphology and cohesion) and aesthetic properties of the chert tools were evaluated using non-destructive techniques (peeling test, spectrophotometry and optical surface roughness), followed by destructive techniques, such as SEM and XRD.

Soldering Electronics to Smart Textiles by Pulsed Nd:YAG Laser

Experts attest the smart textiles market will have high growth potential during the next ten years. Laser soldering is considered to be a good contacting method because it is a contactless process. For this reason, it is intended to investigate the contacting process of printed circuit boards (PCB) to isolated conductive textile strips by means of a ytterbium-doped fiber laser (1064 nm). During the investigation, the copper strands in the textile tape were stripped by the laser and soldered to the PCB without any transport of the textile. Therefore, we investigated different sets of parameters by means of a design of experiment (DoE) for different types of solder pastes. Finally, the joinings were electrically analyzed using a contact resistance test, optically with a REM examination, and mechanically using a peeling test.

Critical Insights in the Application of Convection and Pressure Curing in Eliminating DAF Voids

The absent of reliable production controls for Die Attach Film (DAF) voids detection allowed defect escapee for Ball Grid Array (BGA) devices using non-conductive film material leading to gross assembly rejection and customer complaints. This paper presents the evaluation of pressure curing as an alternative to the convection curing in die attach process with additional capability to eliminate the DAF voids on non-conductive films. Through Analysis of Variance (ANOVA) analysis, green peeling test, Scanning Acoustic Microscope (SAM), cross section analysis and reliability test performed between samples arrives to the conclusion that pressure oven has a significant impact in die shear strength improvement and DAF voids elimination with positive response in reliability requirement. The result of the study improves the assembly flow and production control of BGA devices through the transition of convection to pressure curing technology.

Basic Protocol for On-Site Testing Consolidant Nanoparticles on Stone Cultural Heritage

Currently the application of consolidants based on nanoparticles is common practice among restorers. Consolidants should not modify the properties of original materials according to international recommendation, which requires previous studies to decide the optimal option. The selection must be based on empirical results, and not only in the expertise of the restorer, because the consolidant’s effectiveness is influenced by its own properties and other factors such as the characteristics of the artwork (elemental composition, porosity, texture, etc.) and its context (temperature, relative humidity, etc.). Moreover, new protocols must be sustainable and compatible with on-site restoration. A new protocol to test consolidant nanoparticles has been designed and assessed. This is based on easy trials and low-cost techniques—digital microscope, colorimeter, peeling test and ultrasound—that could be employed by restorers in situ. In this paper, different consolidant nanoparticles were tested on stones from two historical quarries. The first treatment was SiO2 nanoparticles, and the second, a new nanocomposite of Ca(OH)2 and ZnO quantum dots that allows us to measure penetration depth easily and discern the treated areas under UV lights. This second treatment was the best option for the studied stones, validating the protocol designed for the choice of consolidants.

Fabrication of glass/carbon fiber-reinforced Al-based composites through deformation bonding

The goal of the present study is to fabricate the short fiber-reinforced metal matrix composites by accumulative roll bonding. Various mixtures of fibers including 100 glass, 95 glass/5 carbon and 80 glass/20 carbon (all in wt.%) were used as the reinforcement. In order to investigate the bonding quality at layer interface, the composites with various fiber mixtures were produced by cold roll bonding. The bonding strength of the composites under different processing conditions including the fiber mixture, reduction in thickness and post-rolling annealing was measured by the peeling test. The 95 glass/5 carbon mixture was used to fabricate the fiber-reinforced composite through accumulative roll bonding. The fiber distribution, tensile properties and wear behavior of the composite were investigated at various numbers of accumulative roll bonding cycle. It was found that during accumulative roll bonding, the fiber clusters were broken and fragmented into smaller pieces. Results showed that the tensile strength and wear resistance of the composite enhanced with increasing the number of accumulative roll bonding cycles.