|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
Lead-free solder joint and environmental impacts
Kudláček, František ; Zatloukal, Miroslav (referee) ; Starý, Jiří (advisor)
The aim of this bachelor thesis is to determine the effect of low-temperature lead-free solder during the aging process. The theoretical part deals with the types of lead-free solders and solder pastes used for the production of electrical circuits. In the practical part we deal with the design and measurement of the PCB. For our analysis, we pay more attention to the solder paste type Sn42Ag1Bi57 and its temperature profile. A four-point measurement method is used for evaluation, which shows us the difference between the measured values.
|
|
|
Structual welding of aluminium alloy
Blahák, Petr ; Hála, Michal (referee) ; Kubíček, Jaroslav (advisor)
The project elaborated in frame of engineering studies branch 2303R002 presents a project that contains welding a structure made of aluminium alloy. There were two usable methods selected, based on literal study of welding aluminium alloys, TIG welding and friction welding, and these were compared with alternative methods of joining, hard soldering and bonding. A work procedure was made for TIG method, soldering and bonding and four experimental joins were made thereafter. Project compares these methods mainly in economical way, also in way of technological difficulties and in way of observance the strength of base materials. Project also deals with problems with lowering strength of base material in heat affected area, burn out of thin material, tendency of aluminium to fill with hydrogen, quick oxidation and consequent hard surface layer emerging on the aluminium.
|
|
|
Optimization of surface treatment of stainless steels
Mačátová, Lucie ; Žák, Ladislav (referee) ; Kubíček, Jaroslav (advisor)
The project deals with the processes of degreasing industry and testing new laser cleaning process, which has been experimentally verified and tested in the production process. Project also deals with soldering in general as a technology of joining metals. Included are the main components of the soldering, such as solder, flux, the types of connections and their use, ways of soldering and last but not least the soldering corrosion-resistant steel.
|
|
|
THE APPLICATION OF NANOMATERIALS FOR LEAD FREE SOLDERS DEVELOPMENT
Pešina, Zbyněk ; Pinkas, Jiří (referee) ; Spousta, Jiří (referee) ; Sopoušek, Jiří (advisor)
The present dissertation is motivated by the search for alternatives of lead-free soldering by nanoparticles of metals and their alloys. The research focuses on the possibility of replacing lead-free solders by nanoparticles. This issue is currently being addressed by the use of lead-free solders but their properties are not entirely equivalent to properties of lead-tin based alloys. The theoretical part of the dissertation first summarizes up-to date knowledge on the development of lead-free alloys currently used for soldering in the electronics. The work compares these lead-free solder candidates with previously used Pb-Sn alloys. The second section of the theoretical part is devoted to nanotechnology that offers possible solutions of problems associated with the use of lead-free solders. The text contains a description of the properties of nanocrystalline materials in comparison with those of compact alloys having the same chemical composition. The possibility of preparation of nanoparticles and potential problems associated with small particle sizes are also presented. Introduction of the experimental part focuses on the preparation of nanoparticles of pure metals and alloys by chemical and physical ways as well as on an instrumentation for characterisation and analysis. Attention is focused on the silver in nanoparticle form that exhibits the low temperature sintering effect, which is thermally activated by decomposition of oxide envelope covering the Ag nanoparticles. This factor is critical for low-temperature sintering and thus also for possible future applications. The thermal effects of the low sintering process were studied by methods of thermal analysis. The preparation of the Cu / Ag nano / Cu joints was carried out in-situ in inert atmosphere and under the action of atmospheric oxygen. In both cases varying conditions of thermal treatment were used. The cross sections of the prepared joints were then used for the metallographic analysis of the local mechanical properties of the resulting silver layer, for the chemical composition evaluation of the resulting layers of the joint, and for the microstructure study. Strength characteristics are represented by testing shear strength of individual joints.
|
|
|
Unconventional Metals Hardsurfacing Technologies
Krejčí, Vojtěch ; Šárka,, Šimůnková-Houdková (referee) ; Čelko, Ladislav (advisor)
The main objektive of the bachelor thesis is to evolve problems of metalic surface welding and to implement the basic partition of the most expanded used technologies of surface welding. Sometimes we can see the term deposition metalic surface welding too but in practice is used technical term metalic surface welding. The introdution includes the basic acquaintance with problems and the characterization of the proces of surface welding including the summary of its advantages and disadvantages. In other chapters we aim on individual technologies of surface welding, its principle and using in technical practice. Simultaneously is worked out the overview of already unused or minimally used technologies of surface welding. After the presentation of individual technologies follows the section dealing with partition of materials used for surface welding by the basic material as well as surface welding materials at the present technical practice. In the experimental section of thesis follows selected examples of using the presented technologies of surface welding in practice at present.
|
|
|
Modification of PCB cleaning process after removing BGA component
Procházka, Adam ; Bžoněk, Tomáš (referee) ; Řezníček, Michal (advisor)
This bachelor thesis deals with the modification of DPS cleaning process after the removal of BGA components. The thesis is divided into five main parts including the introduction and conclusion. The introduction comprises an assignment and aim of the thesis. The first, theoretical, part then deals with different kinds of soldering, individual types of solders and the rework process itself. The second part examines the whole practical part in detail, from the proposal of the test printed circuit board to its mounting, soldering and subsequent testing. Also, it explains the practical tests for connectors. The third part then describes the board testing by thermal cycling. The last part consists of the summary of results, a comparison of individual soldering pastes and conclusion.
|
|
|
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.
|
guest ::
