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Study of the solidification structure of a solder joint of an SMD resistor during passing an electric current
Voda, Erik ; Otáhal, Alexandr (referee) ; Skácel, Josef (advisor)
This bachelor’s thesis deals with the analysis of solder alloys and intermetallic compounds. The subject of its investigation is the microstructure of the solder-joint and the influence of electric current on its formation. The proposed experiment involves the soldering of thick-film SMD resistors on FR4 substrate with lead-free solder paste SAC 305 while passing an electric current. The resulting samples are subsequently examined by optical and electron microscopy methods. The analysis consists of processing the images taken and comparing between the samples soldered with and without electric current.
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Cooling effect on growth of intermetallic compounds in lead-free solder joints
Faldyna, Martin ; Novotný, Marek (referee) ; Vaško, Cyril (advisor)
This work deals with issues of process optimalization of lead-free soldering. The aim of this work is demonstrate of cooling on grow intermetallic layers during lead-free solde ring process and a hold intensity of cooling on joint quality. The experiment was performed with two types of solder pastes: Sn/Ag/Cu a Sn/Bi/Zn. The final samples were appraised in light of wet-ting, size of intermetallic layers, optical estimation solder and sudar stress test.
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Comparison of solders for power modules
Spaček, Marek ; Boušek, Jaroslav (referee) ; Hejátková, Edita (advisor)
Táto práca podáva náhľad na výkonové polovodičové moduly, technológie v nich požívané a niektoré procesy používané na ich výrobu. Popisuje aj niektoré kvalitatívne kritériá pre spájkovaný spoj medzi DBC substrátom modulu a jeho základovou doskou a metódy používané na ich inšpekciu. Na koniec porovnáva vlastnosti 6-zložkovej vysoko spoľahlivostnej spájky 90iSC vyvinutej firmou Henkel so štandardnou spájkou požívanou na výrobu modulov vo firme SEMIKRON pri použitím rôznych spájkovacích programov, použitím röntgenovej inšpekcie, SAM a metalurgických rezov.
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Effect of electron beam remeltin on binary mixtures deposited by the cold spray method
Novotný, David ; Řehořek, Lukáš (referee) ; Čupera, Jan (advisor)
This bachelor’s thesis deals with the effect of an electron beam remelting on binary mixtures of Fe-Al and Ni-Al, which were deposited by Cold spray. The Research study is focused on the basic principles of function and usage of the electron beam technology and the Cold spray method. Furthermore, binary systems of Fe-Al and Ni-Al are, along with their binary diagrams, also described in this part. In the Experimental part, the samples were remelted by an electron beam and consequently, the changes in microstucture were examined using electron and optical microscope.
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SMD Rework station
Szabó, Michal ; Roubal, Zdeněk (referee) ; Szabó, Zoltán (advisor)
This thesis describes the theory of solder joint and conditions under which it is formed correctly. Further, methods of hand soldering are discussed, and possibilities of temperature regulation of soldering tip are analyzed. Methods of creating a soldering station and its key features are depicted. In practical part, the solution of how to create a soldering station with soldering iron, desolder gun and heatgun is given and is constructed. While testing a defect is found that prevents the power portion of soldering station to function properly and prevents completion.
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Reaction synthesis of bulk intermetallic materials in Ti Ni system form kinetic spraying deposits
Dyčka, Martin ; Moravčík, Igor (referee) ; Jan, Vít (advisor)
Bachelor’s thesis deals with intermetallic compounds which are formed in nickel-titanium binary system. The theoretical part of this thesis deals with the best known titanium based intermetallics, diffusion and possible processing technologies of intermetallic materials. In experimental part, a nickel-titanium coating created by cold spray technique was used. The changes in microstructure depending on annealing temperature were analysed. The results contain photographs of microstructure and fractures, values of microhardness and results of chemical analyses.
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WETTABILITY OF PCB SURFACE FINISHES
Minář, Jan ; Jana, Toulová (referee) ; Starý, Jiří (advisor)
This bachelor’s thesis with measuring of wetting characteristics by the wetting balance method for samples of different surface finishes from the firm Gatema. It deals with influence of the isothermal aging and reflow processes on wetting characteristics of surface finishes ENIG, HAL and immersion tin. The influence of intermetallic layer on the overall wettability is studied in case of the surface finish of immersion tin. Also deals with the wettability of the nickel layer, after stripped off gold, in case of the surface finish of ENIG.
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Studium magnetických kvantově kritických jevů na uranových sloučeninách
Opletal, Petr ; Pospíšil, Jiří (advisor) ; Javorský, Pavel (referee)
Motivation of this thesis is a study of magnetic phase diagram of the pseu- doternary system UCoxRu1−xAl. Three single crystals UCo0.19Ru0.81Al, UCo0.27Ru0.73Al and UCo0.40Ru0.60Al have been successfully prepared by Czochralski method. Composition was confirmed by EDX analysis and quality of single crystals was checked by Laue method. Crystallographic parameters and occupancies were de- termined by X-ray powder diffraction. Data analysis confirmed strong uniaxial magnetocrystalline anisotropy (c is the easy magnetization axis) and existence of hard and soft ferromagnetic phase. Curie temperature TC = 41 K was determined for UCo0.40Ru0.60Al and phase transition from the soft ferromagnetic phase to the hard one takes place at 35 K. UCo0.27Ru0.73Al becomes ferromagnetic at TC = 18 K and the transition from the soft to the hard ferromagnetic phase takes place somewhere around 7 K. UCo0.19Ru0.81Al is paramagnetic down to 2 K. Analysis of the temperature dependence of resistivity and heat capacity reveals signatures of non-Fermi liquid behaviour due to proximity of quantum critical point. 1
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