Dec 14, 2019   9:44 a.m. Branislava, Bronislava
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doc. Ing. Lýdia Rízeková Trnková, PhD.
Identification number: 1461
University e-mail: lydia.trnkova [at]
Odborná asistentka CSc.,PhD. - Institute of Materials (MTF)

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Basic information

Basic information about a final thesis

Type of thesis: Habilitation thesis
Thesis title:Lead-freee solders for electronics industry
Written by (author): doc. Ing. Lýdia Rízeková Trnková, PhD.
Department: Institute of Materials (MTF)
Opponent 1:prof. Ing. Roman Koleňák, PhD.
Opponent 2:prof. Ing. Dana Bolibruchová, PhD.
Opponent 3:doc. Ing. Ján Viňáš, PhD.
Final thesis progress:Final thesis was successfully defended.

Additional information

Additional information about the final thesis follows. Click on the language link to display the information in the desired language.

Language of final thesis:Slovak

Slovak        English

Title of the thesis:Lead-freee solders for electronics industry
Summary:Electronic industry reqires materials with good thermomechanical properties. Economic benefits and environmental aspects are the main demands. In soldering technology it is necessarily to employ lead-free soldering with respect to reliability of sodered components as well as whole electronic systems. From the safety point of view it is very important to produce strong connection of soldered component with the substrate. This connection is arranged by the presence of intermetallic layers between solder-substrate interface, which are formed during soldering. However, the excessive growth of intermetallic layers may result in a decrease of reliability or a complete failure of soldered joints. There are several issues accompanied with the utilization of Sn-Ag-Cu solders as alternative alloy for lead-free soldering. One of them is the higher soldering temperature, which leads to contamination of solder bath by dissolved copper. The copper addition in liquid solder during soldering can also have a negative effect on the soldering alloys properties. In the present work we investigated a number of ternary hypoeutectic alloys of the Sn-Ag-Cu type. The Sn99Ag0.3Cu0,7 alloy (element concentrations given in wt%) was chosen as the starting material. In order to understand the influence of increasing copper concentration, three different alloys were also examined. These alloys had copper concentrations of 0,85, 1,0 and 1.2 wt.% respectively. In the thesis we studied both thermal properties, mechanical strength and interface microstructure, as well as wetting and spreadability of the alloys. The fractography analysis and chemical microanalysis of the fracture surfaces after tensile testing were also carried out. Moreober, the specimens were subjected to an electrochemical corrosion test in 3,5% saline solution. The analyses were performed by light optical microscopy, scanning electron microscopy and differential scanning calorimetry. Furthermore, universal testing machine for tensile measurements of soldered specimens and electrochemical cell for corrosion tests were also employed.
Key words:lead-free solders, Sn-Ag-Cu alloys, microstructure

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