Nanocomposite inks composed of nickel–silver core–shell and silver nanoparticles (NPs) can combine the advantages of lower cost, high conductivity, and low-temperature sintering processes, which have attracted much attention in the development of materials for printed flexible electronics. In this context, in the present paper, we report the process of preparation of nanocomposite ink containing nickel–silver core–shell nanoparticles, as the main filler, and silver nanoparticles, as doping material, and their application for the fabrication of conductive coatings. It was found that the addition of a low concentration of Ag NPs to ink formulation based mainly on low-cost Ni-Ag NPs improves the conductive properties of coatings fabricated by ink deposition on a glass substrate. Two types of prepared nanocomposite ink coatings showed promising properties for future application: (1) doped with 0.5% of Ag NPs sintered at 200 °C as low cost for larger industrial application and, (2) containing 1% of Ag NPs sintered at 150 °C for the fabrication of conductive printed patterns on flexible substrates. The conductivity of such nanocomposite films was similar, about of 6 × 10⁶ S/m, which corresponds to 35% of that for a bulk nickel.

The Low Temperature Joining Technique(LTJT) using silver compounds enables to significantly increase the thermal conductivity between joined elements, which is much higher than for soldered joints. However, it also makes difficult to measure the thermal conductivity of the joint.The Laser Flash Analysis(LFA) is a non-intrusive method of measuring the temperature rise of one surface of a specimen after excitation with a laser pulse of its other surface. The main limitation of the LFA method is its standard computer software, which assumes the dimensions of a bonded component to be similar to those of the substrate, because it uses the standard Parker’s formula dedicated for one-dimensional heat flow. In the paper a special design of measured specimen was proposed, consisting of two copper plates of different size joined with the sintered silver layer. It was shown that heat properties of these specimens can also be measured after modifying the LFA method. The authors adapted these specimens by masking the false heat signal sourced from the uncovered plate area. Another adaptation was introducing a correcting factor of the heat travel distance, which was calculated with heat-flow simulations and placed into the Parker’s formula. The heat-flow simulated data were compared with the real LFA measurement results, which enabled estimation of the joint properties,e.g.its porosity.

Thermal silver plating method by means of nanosilver-based paint could be an alternative to electrochemical processes. Electrochemical silver layering on aluminium is typically achieved with an intermediate layer, which provides very good adhesion of the layer to the aluminium surface but increases the resistance of the whole junction system. In the method of silver plating promoted by the authors, the intermediate layer is eliminated. The layer of silver paint was applied directly on the aluminium surface by spraying using aerograph. Procured silver layers, according to ISO 2409, prove proper adhesion to aluminium. The value of contact resistance with a pressure of 300 N cm−2 and current load of 200 A is 0.03 μΩ mm−2, which is comparable to the contact resistance of layers generated by electrochemical means. This new method decreases the level of toxic waste emission and therefore is less harmful for the natural environment. It is also cheaper and simpler than the electrochemical process. An additional advantage is the possibility of silver plating of the chosen surfaces with various shapes.

Purpose: The purpose of this paper is to present results of the studies on modification of ethylene-vinyl acetate (EVA) encapsulation foil to be used as thermal interface material (TIM). It is estimated that poor thermal management in electronic devices can cause over 50 per cent of failures. As the junction temperature rises, the failure rate for electronics increases exponentially. To ensure sufficient heat transfer from its source, TIMs are used in various circuits. On the other hand, it is important to ensure high electric resistivity of the designed TIM. Design/methodology/approach: The focus of the investigation was twofold: modification of EVA with both graphene oxide (GO) and silver nanopowder (nAg); and TIM applicability through lamination of photovoltaic cells with standard and modified EVA foil. The main problem of a new type of encapsulant is proper gas evacuation during the lamination process. For this reason, reference and modified samples were compared taking into account the percentage of gas bubbles in visible volume of laminated TIM. Finally, reference and modified TIM samples were compared using differential scanning calorimetry (DSC) and laser flash analysis (LFA) measurements. Findings: The proper parameters of the lamination process for the modified EVA foil - with both GO and organometallic nAg particles - were selected. The nAg addition results in an increase in thermal conductivity of the proposed compositions with respect to unmodified EVA foil, which was confirmed by DSC and LFA measurements. Originality/value: The experiments confirmed the potential application of both EVA foil as a matrix for TIM material and nAg with GO as an active agent. Proposed composition can bring additional support to a solar cell or other electronic components through effective heat removal, which increases its performance.