Peter Lukacs

Surface analysis of polymeric substrates used for inkjet printing technology

Purpose – This paper aims to find an optimal surface treatment of commonly used polymeric substrates for achieve the high adhesion of printed structures. For this reason, the investigation of substrates surfaces from different perspectives is presented in this paper. Design/methodology/approach – The contact angle measurements as well as the roughness measurements were realised for the analysis of surface properties of investigated substrates. The impact of applied chemical agents for surface treatment onto the wettability is analysed for polyimide, polyethylene terephthalate and polyethylene naphthalene substrates. Findings – The results prove the correlation among wettability, surface energy and work of adhesion with respect to the theoretical background. The surface treatment of polymeric substrates by chemical agents, such as acetone, toluene, ethanol, isopropyl and fluor silane polymer, has a significant impact onto the wettability of substrates which affects the final deposition process of nanoinks....

Investigation of nano-inks’ behaviour on flexible and rigid substrates under various conditions

Purpose This paper aims to find the optimal deposition conditions for achieving the homogenous structure of the silver layers onto three types of polymeric substrates as well as on the rigid substrates. For this reason, the detailed investigation of the silver-based layers deposited at different technological conditions by microscopic methods is presented in this paper. Design/methodology/approach The special test pattern has been designed and deposited at different substrate temperatures by using two types of generally available silver-based nano-inks. Cross-sections and 3D profiles of the deposited silver layers have been profoundly analysed by using the optical profiler Sensofar S Neox on the generally used polymeric (PI, PET and PEN) and rigid substrates (951 and 9K7 LTCC, glass and alumina). Findings The results prove the strong correlation between the substrate temperature during the deposition process and the final shape of the created structure which has the a direct impact on the layers’ homogeneity. The results also prove the theory of the coffee ring effect creation in the inkjet printing technology. Originality/value The main benefit of this paper lies in the possibility of the homogeneity achievement of the deposited silver-based layers on the several polymeric and rigid substrates by managing the temperature during the deposition. The paper also offers the comparative study of nano-inks’ behaviour on several polymeric and rigid substrates.

Dependence of electrical resistivity on sintering conditions of silver layers printed by InkJet printing technology

Purpose The purpose of this paper is to find optimal sintering conditions of silver-based nano-inks for achieving the high electrical conductivity of the deposited layers applied on polyimide foils as well as the influence of ageing on the electrical conductivity. Therefore, the investigation in the field of silver layers deposited by inkjet printing technology is presented in this paper. Design/methodology/approach The four-point resistance measurements were realized for a detailed and precise analysis of the resistance of two different silver layers under different sintering conditions depending on the type of nano-ink varied about the recommended values. Highly accelerated stress tests (HASTs) were also applied as an ageing method for confirmation of the high electrical stability of the silver layers. Findings The results prove the strong influence of the temperature and the time of the sintering process on the sheet resistance of the investigated silver-based layers deposited by inkjet printing technology on polyimide foils. The HASTs caused significant changes in the electrical conductivity for both nano-inks presented in this paper. The existence of noticeable dependence among the resistivity, thermal treatment and ageing was proved. Originality/value The main benefit lays in the optimization of sintering conditions to improve the electrical conductivity of the silver layers. The paper also presents a new approach for a stability analysis of the silver layers by HASTs.

UWB antenna based on nanoparticles of silver on polyimide substrate

The aim of this paper is describing a design, realization and measurement of ultra wide band (UWB) antenna by inkjet printing technology on polyimide substrate DuPont™ Kapton® HN 50.8 μm. For this purpose we used conductive silver based nano-ink AX JP-6n by Amepox Microelectronics LTD with particle size range between 3 - 7 nm in diameter. The realized antenna was designed and simulated in Ansoft HFSS™ 13.0. The frequency bandwidth of this UWB antenna is between 5.5 to 11.7 GHz that is according to decision of Federal Communications Commission. The impedance matching was realized by length of feeding element to 50 Ω. Paper includes the theoretical background of inkjet printing technology applied within UWB antenna realization.

Improvement of the evaluation of inkjet printed silver based layers’ adhesion

Abstract This paper presents the improved method of analysis and evaluation of the silver layers’ adhesion printed by inkjet printing technology. The generally known method for adhesion measurement of layers and coatings according to the standards ASTM D3359 and ISO 2409 has been improved by development of the automatic evaluation software of achieved results from cross cut tests. The developed evaluation tool offers the possibilities of calculation the detached area, rotation of the image, setting the threshold and the automatic classification according to the mentioned standards. The inaccuracy caused by samples’ assessment by humans is mainly eliminated by using of this tool. The developed evaluation tool has been applied to experimental works oriented to analysis of the adhesion of two commercially available silver based nano-inks on two polymeric based substrates (PI and PET). For this purpose, different sintering conditions have been applied to analysed samples. The achieved results show the differences between the investigated nano-inks’ adhesion on two types of polymeric substrates. The adhesion of silver layers can be optimized by controlling the sintering conditions. By developing the software tool the simple and inaccurate method of adhesion analysis has been upgraded to the appropriate technique to the silver layers’ adhesion testing. The improved method for adhesion measurements can serve as a tool for fast and relatively simple technique for technologist.

Simulation of cooling efficiency via miniaturised channels in multilayer LTCC for power electronics

Abstract The aim of this paper is detailed investigation of thermal resistance, flow analysis and distribution of coolant as well as thermal distribution inside multilayer LTCC substrates with embedded channels for power electronic devices by simulation software. For this reason four various structures of internal channels in the multilayer LTCC substrates were designed and simulated. The impact of the volume flow, structures of channels, and power loss of chip was simulated, calculated and analyzed by using the simulation software Mentor Graphics FloEFDTM. The structure, size and location of channels have the significant impact on thermal resistance, pressure of coolant as well as the effectivity of cooling power components (chips) that can be placed on the top of LTCC substrate. The main contribution of this paper is thermal analyze, optimization and impact of 4 various cooling channels embedded in LTCC multilayer structure. Paper investigate, the effect of volume flow in cooling channels for achieving the least thermal resistance of LTCC substrate that is loaded by power thermal chips. Paper shows on the impact of the first chips thermal load on the second chip as well as. This possible new technology could ensure in the case of practical realization effective cooling and increasing reliability of high power modules.

Usability of Various LTCC in Microstrip Filters Construction

Multilayer packages represent a traditional application of Low Temperature Co-fired Ceramics (LTCC) in electronics. Nowadays, the use of the LTCC is becoming very popular in construction of microstrip filters applied in GHz (HF) range. Research and development on the LTCC microstrip filters performed at Technical University of Kosice has revealed yet unexplored possibility of using various LTCC up to 13 GHz and in this way a possibility of microelectronic structure production applied in the communication application. In this study, we will find out a method of shrinkage instability elimination as well as a correlation between shrinkage and mechanical properties. Dimensional accuracy and flatness of the ceramic substrate is the most important factor in the development of the microstrip filters applied in the HF area. The paper reviews LTCC processes from this point of view and shows that the main aspect of LTCC technology is targeting a more precise manufacturing tolerance control in which electrical performance (scattering parameters) is sensitive to the HF area such as realization of fine line microstrip structure.