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21 – 26 of 26Polymeric materials have gained a wide theoretical interest and practical application in sensor technology. They can be used for very different purposes and may offer unique…
Abstract
Polymeric materials have gained a wide theoretical interest and practical application in sensor technology. They can be used for very different purposes and may offer unique possibilities. The paper gives a broad summary about the sensor structures and sensing polymer films used in a wide variety of sensors. Finally, the present status and perspectives as well as the advantages of specific polymer based sensors are summarised.
Daniel Straubinger, István Bozsóki, David Bušek, Balázs Illés and Attila Géczy
In this paper, analytical modelling of heat distribution along the thickness of different printed circuit board (PCB) substrates is presented according to the 1 D heat transient…
Abstract
Purpose
In this paper, analytical modelling of heat distribution along the thickness of different printed circuit board (PCB) substrates is presented according to the 1 D heat transient conduction problem. This paper aims to reveal differences between the substrates and the geometry configurations and elaborate on further application of explicit modelling.
Design/methodology/approach
Different substrates were considered: classic FR4 and polyimide, ceramics (BeO, Al2O3) and novel biodegradables (polylactic-acid [PLA] and cellulose acetate [CA]). The board thicknesses were given in 0.25 mm steps. Results are calculated for heat transfer coefficients of convection and vapour phase (condensation) soldering. Even heat transfer is assumed on both PCB sides.
Findings
It was found that temperature distributions along PCB thicknesses are mostly negligible from solder joint formation aspects, and most of the materials can be used in explicit reflow profile modelling. However PLA shows significant temperature differences, pointing to possible modelling imprecisions. It was also shown, that while the difference between midplane and surface temperatures mainly depend on thermal diffusivity, the time to reach solder alloy melting point on the surface depends on volumetric heat capacity.
Originality/value
Results validate the applicability of explicit heat transfer modelling of PCBs during reflow for different heat transfer methods. The results can be incorporated into more complex simulations and profile predicting algorithms for industrial ovens controlled in the wake of Industry 4.0 directives for better temperature control and ultimately higher soldering quality.
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Keywords
Agata Skwarek, Balázs Illés, Krzysztof Witek, Tamás Hurtony, Jacek Tarasiuk, Sebastian Wronski and Beata Kinga Synkiewicz
This paper aims to investigate the quality and reliability of solder joints prepared from Pb-free alloys on direct bounded Cu (DBC) substrates. Two types of solder alloys were…
Abstract
Purpose
This paper aims to investigate the quality and reliability of solder joints prepared from Pb-free alloys on direct bounded Cu (DBC) substrates. Two types of solder alloys were studied: Sn90.95Ag3.8Cu0.7Sb1.4Ni0.15Bi3.0, with a high melting point of 225°C, and Sn42Bi58, with low a melting point of 138°C.
Design/methodology/approach
Capacitor components of size 1806 were soldered on DBC substrates by using convection reflow soldering and vacuum vapor-phase soldering technologies. A part of the samples was subjected to the thermal shock test. The structure of the solder joints and the content of the voids were investigated using three-dimensional X-ray tomography. The mechanical strength of the joints was evaluated using the shear force test, and the microstructure of the joints was studied on metallographic cross sections by using scanning electron microscopy.
Findings
It was found that the number of voids is not related directly to the mechanical strength of the solder joints. The mechanical strength of the solder joints depends more on the amount of Ag3Sn precipitation, Au precipitation and the intermetallic layer in the solder joints. In some cases, the thermal shock test caused micro-cracks around the Au precipitation because of a mismatch of Au, AuSn4 and Sn in terms of coefficients of thermal expansion.
Originality/value
DBC substrates are usually used for power electronics, where the quality of the solder joints is even more important than in the case of commercial electronics.
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Two members of ISHM‐Hungary, Professor Zsolt Illyefalvi‐Vitéz, ELC representative, and Professor Gábor Harsányi, president and TPC representative, attended the NATO Advanced…
Abstract
Two members of ISHM‐Hungary, Professor Zsolt Illyefalvi‐Vitéz, ELC representative, and Professor Gábor Harsányi, president and TPC representative, attended the NATO Advanced Research Workshop on MCM‐C/Mixed Technologies in Florida, USA, in May co‐sponsored by ISHM‐US and organised by:
B. Waterfield and Geoff Griffiths
At the Annual General Meeting of ISHM‐France, held on 12 June 1991, the following were elected:
The International Society for Hybrid Microelectronics invites the submission of technical papers for presentation at the above event. All original unpublished papers on…
Abstract
The International Society for Hybrid Microelectronics invites the submission of technical papers for presentation at the above event. All original unpublished papers on microelectronics related topics are welcomed.