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Design of an experiment to investigate the influence of mechanical vibrations and electric current during the soldering process
Nohel, David ; Jankovský, Jaroslav (referee) ; Otáhal, Alexandr (advisor)
This bachelor thesis focuses on the investigation of the effects of electrical current and mechanical vibrations on the process of forming a solder joint. The goal was to explore these effects together with the synergy of these two factors and their impact on the mechanical strength and microstructure of solder joints. An experiment was designed and conducted, involving the use of a mechanical vibration device and soldering apparatus with the capability of applying electrical current. The results demonstrated that mechanical vibrations can positively influence the strength of the solder joint, while electrical current significantly affects the structure of intermetallic layers. These findings could contribute to the further development of technologies and materials used in electronic soldering.
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Design of an experiment to investigate the influence of the frequency of mechanical vibrations on the structure of a solder joint
Podolák, Šimon ; Košelová, Zuzana (referee) ; Otáhal, Alexandr (advisor)
The main goal of this bachelor's thesis is to study the influence of vibrations on the structure of solder joints, specifically SAC305 solder paste droplets. The thesis consists of three parts: theoretical, practical, and evaluation of results. The theoretical part focuses primarily on solder joints and the phenomena surrounding them, such as diffusion, voids, crystal morphology, and others. It also describes vibrations and everything related to them, including ultrasound and its use in the field of soldering. The practical part deals with designing workstations for creating individual samples, specifically without vibrations, with 5 kHz vibrations, and with ultrasonic vibrations. This is followed by the process of preparing the samples and modifying them to a state suitable for microscopic examination. The final part involves evaluating the results obtained and comparing the samples with each other.
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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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Design of indirect sensing of gas valve throttle position
Burian, Jaroslav ; Jankovský, Jaroslav (referee) ; Otáhal, Alexandr (advisor)
This thesis deals with the design of a circuit for measuring the throttle position of the PX52 valve from Resideo. The theoretical part discusses the methods whose principle can be used to determine the position of the throttle valve controlled by a stepper motor. Subsequently, the communication protocols that can be chosen between in the design are described. Methods for measuring the mutual properties of the coils were also described. In the practical part, a PCB was created to verify both methods. Furthermore, a program for testing both methods is described in the paper. These methods are compared with each other for different coil variants. Finally, the method is selected and the program is modified for the measurements.
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Optimization of the positioning system of semiconductor chip testing
Kotian, Tomáš ; Jankovský, Jaroslav (referee) ; Otáhal, Alexandr (advisor)
The goal of this diploma thesis was to gather theoretical information on the possibilities of chip testing and subsequently design and apply necessary changes for the semi automatic positioning system, which would ensure its ability to test chips with the use of probe cards. Semi automatic positioning system is a result of a bachelor thesis, which ensured the ability of the machine to provide testing with the use of a resistance system created on a thick layer. The practical part of this thesis is focused on providing an accurate testing of the machine’s parametres and designing and applying necessary changes for the mechanical part of the machine. Furthermore, the thesis also describes the design and creation of an application with automatic detection of a chip, which is used for controlling the machine. The last part of the thesis describes the testing of the machine, which was realized with the use of two different sized chips.
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Design and realization of the pull strength measuring device for SMD
Valíček, Jan ; Klíma, Martin (referee) ; Otáhal, Alexandr (advisor)
This thesis deals with the design and implementation of a device for measuring pull strength by surface mounted devices (SMD). It analyzes the theory of pull strength testing of solder joints with emphasis on standard IEC 62137-1-3 and describes the selection of components utilized to create mechanical construction and electrical parts. These electronic parts made or innovated in this work were control system based on microcontroler Atmega164P, power circuit for stepper motor and communication of measure equipment TEST 321 with PC. The whole design is complemented by simulation of mechanical stress to the critical components using ANSYS. The conclusion summarizes the most important parameters of this equipment.
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Viscometer adjustment for materials of higher viscosity
Laryš, Šimon ; Jankovský, Jaroslav (referee) ; Otáhal, Alexandr (advisor)
The aim of this bachelor‘s thesis is to rebuild and verify the functionality of an old SHEEN CP1 viscometer for measuring soldering and thick-film pastes according to the design from the semester project. The theoretical part presents the basic viscosity calculations for newtonian and non-newtonian substances. The basic methods of viscosity measurement for different types of substances are also explained here. The greatest emphasis is placed on devices that can measure thixotropic substances. The practical part presents a design for a method which reduces the speed of the viscometer and a design for the interconnection of individual components from the semester project and its assembly. Following part contains description of the modules and sensors used and the program part with libraries where functions for individual peripherals were created and explained. The connection of individual components is also explained here. Finally, the functionality of the modified viscometer is verified by measuring the soldering and thick-film paste.
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Wetting of lead-free solders on ceramic substrates
Lipavský, Lubomír ; Otáhal, Alexandr (referee) ; Adámek, Martin (advisor)
This master's thesis deals with issue of lead-free soldering in protective atmosphere with focus on wetting test. Theorethical part is focused on the types of lead-free solders, wettability tests performed on solder joints, different types of soldering or comparison of influence of the base material in regards to the wetting of the solder. The goal of practical part is testing and comparison of spreadability of selected lead-free solder on two conductive surfaces with different concentration of oxygen in protective nitrogen atmosphere. Testing has been performed on ceramic substrate which differs this method from others, performed on organic substrate. For an over-melted solder, the crystal-growth on surface in regards to protective atmosphere concentration is shown.
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