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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.

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.

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.

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.

The purpose of this paper is to study the manufacturing of SAC 305 solder paste with multiwall carbon nanotubes (MWCNT) before and after structure modification and also to investigate the added carbon nanotubes' influence on the technological properties and the microstructure of “nano” solder pastes. This work is a continuation of similar previous studies of SAC solder pastes with silver nanopowder additions.

The authors applied functionalization and esterification methods for the structural modification of the carbon nanotubes. The “nano” solder paste preparation was performed with the use of a two‐stage method of carbon nanotube dispersion in “own‐manufactured” SAC 305 solder paste. To determine the technological properties of the “nano” solder paste, slump, solder ball, wetting and spreading tests were applied according to the existing standards. Standard metallographic procedures were applied for microstructural analysis.

As expected on the basis of the previous studies of SAC solder pastes with silver nanopowders, positive results were obtained for the own‐manufactured SAC 305 solder paste with carbon nanotubes by applying the dispersion method. Also applied were functionalization and esterification methods, whose results showed microstructural changes in the carbon nanotubes. The “nano” SAC solder pastes showed a positive influence on the slump properties, compared to the basic SAC solder paste. The authors proved a negative influence of the carbon nanotubes' addition (dependent on their concentration) on the spreading and wetting of the SAC solder paste on a copper substrate, which provoked the non‐wetting and dewetting phenomena. A slight improvement was observed for the “nano” SAC solder pastes with modified carbon nanotubes. The carbon nanotubes' presence in the solder paste showed a positive effect on the growth reduction of the IMCs' thickness, which depended on the type.

The authors intend to verify the reinforcement effect of the alloys with carbon nanotubes suggested in the literature (the aim of Part II). For this purpose, an assembly process with RC electronic elements on PCBs with Ni/Au and SAC (HASL) finishes will be performed, with the use of the SAC 305 solder paste with modified carbon nanotubes, for the purpose of reflow soldering. Next, measurements of the mechanical strength of the solder joints and their microstructures will be conducted.

It is suggested that further studies of the mechanical properties and the reliability of solder joints are necessary for the practical implementation of the “nano” SAC solder pastes, but taking into account the wetting data, the investigation should be performed only for “nano” pastes with the lowest additions of modified carbon nanotubes.

The paper demonstrates a method of “nano” solder paste preparation by means of a two‐stage dispersion of carbon nanotubes in the own‐manufactured SAC 305 solder paste and a comparison study of the properties of “nano” pastes with the basic SAC solder paste.

Despite almost limitless possibilities of rapid prototyping, the idea of 3D printed fully functional electronic device still has not been fulfilled – the missing point is a highly conductive material suitable for this technique. The purpose of this paper is to present the usage of the photonic curing process for sintering highly conductive paths printed on the polymer substrate.

This paper evaluates two photonic curing processes for the conductive network formulation during the additive manufacturing process. Along with the xenon flash sintering for aerosol jet-printed paths, this paper examines rapid infrared sintering for thick-film and direct write techniques.

This paper proves that the combination of fused deposition modeling, aerosol jet printing or paste deposition, along with photonic sintering, is suitable to obtain elements with low resistivity of 3,75·10⁻⁸ Ωm. Presented outcomes suggest the solution for fabrication of the structural electronics systems for daily-use applications.

The combination of fused deposition modelling (FDM) and aerosol jet printing or paste deposition used with photonic sintering process can fill the missing point for highly conductive materials for structural electronics.

The aim of this paper is to present thermal and mechanical durability of conductive tracks screen-printed with silver polymer pastes on flexible magnetic sheets.

A test pattern that consisted of three straight lines was printed with two different silver pastes on a flexible magnetic sheet and a polyethylene naphthalate (PEN) foil for comparison. Electrical properties of these lines were examined by resistance measurements and their thickness was measured with a digital microscope on cross sections. Cyclic bending was performed to investigate mechanical properties of prepared samples as well as thermal shocks to analyse their thermal durability. Further, samples after thermal shocks underwent cyclic bending to test influence of thermal exposure on mechanical properties of the prepared samples. Changes in the test lines after the thermal and mechanical tests were assessed by resistance measurements and microscopic analysis of surface and internal structure of the test lines.

It was found that the most important factor having an impact on electrical, mechanical and thermal properties of the conductive tracks screen-printed on magnetic sheets is a type of paste used. The samples made with the paste PM-406 exhibited lower resistance because of a higher layer thickness compared to the lines printed with the paste PF-050. The PM-406 layers were revealed to be less durable to mechanical and thermal exposures. An analogical relationship was noticed for the samples made with PM-406 and PF-050 on a PEN foil after thermal shocks and cyclic bending. When magnetic sheets were used as a substrate, a bigger degree of damage was observed for the PF-050 samples, which even lost their electrical continuity after 1,000 bending cycles and thermal cycles, irrespective of their number. Some damage was also noticed in the magnetic sheet after the bending and thermal cycles.

Further investigations are required to examine the influence of other types of thermal exposure on electrical properties of lines printed on magnetic sheets. Other types of magnetic sheets are also recommended to be investigated as substrate materials.

The results reported in this study can be useful among others for designers of radio frequency identification (RFID) systems, which are intended to operate in a challenging environment with strong mechanical and thermal exposures.

This paper contains valuable information concerning mechanical and thermal properties of conductive tracks screen-printed on magnetic sheets which can be used, i.e. for designing of reliable near field communication/high frequency (NFC/HF)-RFID tags suitable for metallic surface.

Multiple fillers are adopted to study the filler influences on electrical and mechanical properties of the conductive adhesives. The performances of the developed nano-enhanced interconnect materials in printing process are also evaluated. The paper aims to discuss these issues.

Micron-sized silver flakes are used as the basic fillers, and submicro- and nano-sized silver spheres and carbon nanotubes (CNTs) are adopted to obtain conductive adhesives with multiple fillers. Differential scanning calorimetry measurement is carried out to characterize the curing behavior of the samples with different fillers, four-probe method is used to obtain the bulk resistivity, shear test is conducted for adhesive strength, and environmental loading test is also involved. Furthermore, printing trials with different patterns have been carried out.

The electrical resistivity of the adhesives with submicro-sized silver spheres does not monotonically change with the increasing sphere proportion, and there exists an optimized value for the ratio of silver flakes to spheres. Samples with relatively small amount of CNT additives show improved electrical properties, while their mechanical strengths tend to decrease. For the printing application, the adhesives with 18.3 volume% filler content behave much better than those with lower filler content of 6 percent. The presence of the nano-particles makes a slight improvement in the printing results.

More detailed printing performance and reliability test of the samples need to be carried out in the future.

The conductive adhesives as interconnect materials exhibit some improved properties with optimized bimodal or trimodal fillers. The additive of the nano-fillers affects slightly on the printing quality of the bimodal conductive adhesives.

This paper aims to investigate the sintering and solid liquid interdiffusion bonding (SLID) techniques to attach AlGaN/GaN-on-Si chips to direct bond copper (DBC) substrate. The influence of metal layers deposited on the backside of AlGaN/GaN-on-Si dies on the assembly process is also investigated.

The authors assumed the value of the shear strength to be a basic parameter for evaluation of mechanical properties. Additionally, the surface condition after shearing was assessed by SEM photographs and the shear surface was studied by X-ray diffraction method. The SLID requires Sn-plated DBC substrate and can be carried out at temperature slightly higher than 250°C and pressure reduced to 4 MPa, while the sintering requires process temperature of 350°C and the pressure at least 7.5 MPa.

Ag-, Au-backside covered high electron mobility transistor (HEMT) chips can be assembled on Sn-plated DBC substrates by SLID technology. In case of sintering technology, Cu- or Ag-backside covered HEMT chips can be assembled on Ag- or Ni/Au-plated DBC substrates. The SLID process can be realized at lower temperature and decreased pressure than sintering process.

For SLID technology, the adhesion between Cu-backside covered HEMT die and DBC with Sn layer loses its operational properties after short-term ageing in air at temperature of 300°C.

In the SLID process, Sn-Cu and Sn-Ag intermetallic compounds and alloys are responsible for creation of the joint between Sn-plated DBC and micropowder Ag layer, while the sintered joint between the chip and Ag-based micropowder is formed in diffusion process.

This paper aims to model solar unit equipped with mirrors with numerical simulation. To augment the efficiency of system, absorber pipe was equipped with fins and nanomaterial was used as carrier fluid. Existence of secondary reflector results in better optical efficiency.

Finite volume approach is used for modeling which is done in two steps. The first one is done to achieve the heat flux distribution and second step to model turbulent flow inside the pipe. Verification has been presented for calculation of important functions (f and Nu). Outputs reveal the impacts of fin height (HF), number of fin (NF), inlet temperature (T_in) and velocity on irreversibility, thermal treatment.

Surface temperature decreases by 0.498, 0.07 and 0.017% with intensify of Re, HF and NF, respectively, when other factors were minimum. With augment of T_in, wall temperature increases about 9.87%. Given NF = 8, HF = 3 mmm, growth of Re makes Darcy factor to decrease about 28.28%, but it augments the Nu by 2.63%. Nu augments with rise of NF and HF about 2.63 and 7.66%. Irreversibility reduces about 29.5 and 11.65% with augment of NF and HF, respectively.

Numerical simulations for solar unit equipped with mirrors were reported in this modeling. To augment the efficiency of system, absorber pipe was equipped with fins and nanomaterial was used as carrier fluid. Existence of secondary reflector results in better optical efficiency. Finite volume approach is used for modeling which is done in two steps. The first one is done to achieve the heat flux distribution and second step to model turbulent flow inside the pipe. Verification has been presented for calculation of important functions (f and Nu). Outputs reveal the impacts of fin height (HF), number of fin (NF), inlet temperature (T_in) and velocity on irreversibility, thermal treatment.

The purpose of this work is to investigate the influence of carbon nanotube additions to solder paste on the solder joints mechanical strength and their microstructure. In our investigation, the basic solder paste contains 85 wt.% of the commercial Sn96.5Ag3Cu0.5 powder (with the particle sizes in the range of 20‐38 μm) and 15 wt.% of the self‐prepared middle activated rosin flux. To this paste we added the 0.01, 0.05 and 0.1 wt.% of the self‐modified CNT by functionalized them by mineral acid and than esterificated by methanol (FCNT_Met) or polyethylene glycol 400 (FCNT_PG). After the pastes had stabilized, the reflow soldering process of “zero ohm” chip resistors on PCBs with Ni/Au and SAC (HASL) finishes was carried out and then shear strength of the solder joints was measured. The correlations between the mechanical strength of solder joins without and with the carbon nanotubes and their microstructure were analysed.

For shear strength measurement of solder joints, the printed circuit boards with Ni/Au and SAC (HASL) finishes was applied. The SAC solder paste with different carbon nanotubes and the basic SAC solder paste as reference were used for this experiment. The automatic SMT line was applied for the paste screen printing; “zero ohms” chip resistors: 0201, 0402, 0603 and 0805 were placing on PWBs and then reflowing according to appropriate time – temperature profile. The shear strength of the solder joints was measured. For the solder joints microstructure analysis, the standard metallographic procedures were applied. Changes in the microstructure, the thickness of the intermetallic compounds and their chemical compositions were observed by means of the SEM equipped with EDS.

As the authors expected, the SAC solder paste with the carbon nanotubes addition improve the solder joints shear strength of the chip resistors mounted on PCBs with Ni/Au and SAC (HASL) finishes. The carbon nanotubes addition positive effects on IMCs thickness because of blocking their excessive growth.

It is suggested that further studies are necessary for the confirmation of the practical application, especially of the reliability properties of the solder joints obtained using solder paste with chosen carbon nanotubes.

Taking into account the shear strength data, the best results of the “nano” SAC solder pastes were obtained for the lowest addition of the carbon nanotubes modified by esterification process, especially by the methanol compared to the polyethylene glycol 400.

The obtained results made it possible to draw conclusions regarding the correlation between the output of the mechanical results and the amount of the added carbon nanotubes, and also the microstructure and thickness of the IMCs of the “nano” solder joints. It can be useful from practical point of view.

New types of substrates were used for fabrication of printed electroluminescent structures. Polymer foils mainly used as substrates for such optoelectronic elements were replaced with paper and textiles. Printing on non-transparent substrate requires elaboration of printed transparent electrode, while usually polyester foils with sputtered ITO transparent electrodes are used. The paper aims to discuss these issues.

Electroluminescent structures were fabricated with elaborated polymer compositions filled with nanomaterials, such as carbon nanotubes and graphene platelets, dielectric and luminophore nanopowders. Structures were printed as “reverse stack”, where transparent electrode is printed on top of the last luminophore layer. For that carbon nanotubes and graphene platelets filled composition was used, deposited with spray-coating technique.

Main issue with new substrates is proper wetting with the use of screen-printing pastes, and much higher roughness especially for textiles.

Fully functional structures were obtained, but several disadvantages were observed that needs to be eliminated in further studies.