This project consists of three parts. The first part is aimed to summarize list of actual packaging systems and especially systems using 3D construction. Project continues in the second part, which is more practical and contains design and production of organic and inorganic testing substrates for lead-free soldered 3D structures. Last experimental part is about tests performed on soldered substrates and evaluation of results of these practical tests.

This work is considered about changes of electric conductivity in lead-free soldered joint's affected by current and thermal stress. The theoretical part describes factors influencing the solder joint electric conductivity and solder joint reliability. The basis of the practical part is the design of the testing method of the soldered joint's electric conductivity. The aim of this part is to measure and observe changes of solder joint electric conductivity after current and thermal stress in various material a procedural combinations.

The thesis deals with problems concerning lead free soldering especially the study of the structure of solder joints and their reliability. The thesis evaluates lead free solder alloys. The theoretical part includes basic principles of soldering and methods of investigating solder joints reliability. The experimental part deals with the impact of water cooling and vibration on solder joint structure. Both methods are tested and are evaluated with regard to their reliability. The used tests include X-ray inspection, optical inspection, mechanical tests, investigating joint structure with electrone microscope.

Sabemos que em placas de circuito impresso montadas com tecnologia SMD Surface Mount Device podem ocorrer problemas com a migração eletroquímica. O fenômeno aparece principalmente porque os novos encapsulamentos possuem terminais com espaçamentos muito próximos. A migração eletroquímica pode tornar-se um potencial problema no processo de soldagem eletrônica quando é utilizado a tecnologia Lead Free na montagem das placas. O processo de migração eletroquímica ocorre quando temos metal, isolante e metal, em ambiente de alta umidade e sobre polarização elétrica, o metal deixa a posição inicial em forma de íon e se redeposita sobre o isolante. Em uma placa de circuito impresso, dois terminais adjacentes podem tornar-se eletrodos, dessa forma as dendritas crescem do cátodo para o ânodo. Podem aparecer diferentes morfologias com diferentes elementos envolvidos no processo de migração, dependendo da composição da pasta de solda ou acabamento da placa de circuito impresso. Uma estrutura do tipo pente comb feita sobre laminado FR4 foi utilizada nos experimentos. A distância entre as trilhas foram de 102 e 254 mícrons para simular uma distancia real dos terminais dos dispositivos. Os fatores considerados durante os experimentos foram: A distancia entre os terminais na estrutura (102 ou 254 mícrons), tensão aplicada (2 ou 3 V). Foi observado que a pasta de solda e o acabamento final não influenciam no processo de migração eletroquímica. O Estanho foi o principal metal que migrou. Todos os resultados obtidos nesse estudo concordam com a literatura. / It is well known that in printed circuits boards assembled by SMT technology may occur Electrochemical migration (ECM). This phenomenon appears mainly because the new packaging has the terminals very close. Also the Electrochemical migration may become a potential reliability problem in electronic soldering when lead free technology is used in soldering electronic devices. Electrochemical migration is an electrochemical process where metal on an insulating material, in a humid environment and under an applied electric field, leaves its initial location in ionic form and redeposit. In a PCB two adjacents terminal may behave as electrodes so the dendrites grow from cathode to anode. It can show different morphologies with the different migration elements involved depending on the solder paste composition or PCB surface finishing. A structure with a comb shape printed on FR4 substrate was used in the experiments. The distance between the fingers in the structure was 102 or 254 microns, in order to simulate a real distance between dispositive terminals. The factors considered during the experiments were surface finishing (ENIG or HASL), solder paste composition, distance between terminals (102 or 254 microns) and applied voltage (2 or 3 V). It was observed that the solder paste and the surface finishing dont influence the ECM process. Tin was the main metal that migrates. All the results obtained in these study agrees with the literature.

Sabemos que em placas de circuito impresso montadas com tecnologia SMD Surface Mount Device podem ocorrer problemas com a migração eletroquímica. O fenômeno aparece principalmente porque os novos encapsulamentos possuem terminais com espaçamentos muito próximos. A migração eletroquímica pode tornar-se um potencial problema no processo de soldagem eletrônica quando é utilizado a tecnologia Lead Free na montagem das placas. O processo de migração eletroquímica ocorre quando temos metal, isolante e metal, em ambiente de alta umidade e sobre polarização elétrica, o metal deixa a posição inicial em forma de íon e se redeposita sobre o isolante. Em uma placa de circuito impresso, dois terminais adjacentes podem tornar-se eletrodos, dessa forma as dendritas crescem do cátodo para o ânodo. Podem aparecer diferentes morfologias com diferentes elementos envolvidos no processo de migração, dependendo da composição da pasta de solda ou acabamento da placa de circuito impresso. Uma estrutura do tipo pente comb feita sobre laminado FR4 foi utilizada nos experimentos. A distância entre as trilhas foram de 102 e 254 mícrons para simular uma distancia real dos terminais dos dispositivos. Os fatores considerados durante os experimentos foram: A distancia entre os terminais na estrutura (102 ou 254 mícrons), tensão aplicada (2 ou 3 V). Foi observado que a pasta de solda e o acabamento final não influenciam no processo de migração eletroquímica. O Estanho foi o principal metal que migrou. Todos os resultados obtidos nesse estudo concordam com a literatura. / It is well known that in printed circuits boards assembled by SMT technology may occur Electrochemical migration (ECM). This phenomenon appears mainly because the new packaging has the terminals very close. Also the Electrochemical migration may become a potential reliability problem in electronic soldering when lead free technology is used in soldering electronic devices. Electrochemical migration is an electrochemical process where metal on an insulating material, in a humid environment and under an applied electric field, leaves its initial location in ionic form and redeposit. In a PCB two adjacents terminal may behave as electrodes so the dendrites grow from cathode to anode. It can show different morphologies with the different migration elements involved depending on the solder paste composition or PCB surface finishing. A structure with a comb shape printed on FR4 substrate was used in the experiments. The distance between the fingers in the structure was 102 or 254 microns, in order to simulate a real distance between dispositive terminals. The factors considered during the experiments were surface finishing (ENIG or HASL), solder paste composition, distance between terminals (102 or 254 microns) and applied voltage (2 or 3 V). It was observed that the solder paste and the surface finishing dont influence the ECM process. Tin was the main metal that migrates. All the results obtained in these study agrees with the literature.

<p>Företag kan behöva förändra sitt sätt att arbeta av flera olika skäl. Marknaden ställer krav på billigare lösningar med bibehållen kvalitet. Myndigheter ställer krav på större miljö­hänsyn. Syftet med den här uppsatsen är att granska tre olika företags förändringsarbete i samband med att RoHS-direktivet föreskrev att bly inte skall användas vid lödning. Ett företag har helt ställt om sin produktion, ett företag kör blandad produktion och ett av företagen endast en liten produktion med blyfritt eftersom dess kunder omfattas av de undantag som finns i direktivet. Undersök­ningen har utförts som kvalitativa intervjuer med miljö- och processansvariga på de olika före­tagen och visar att företagen haft olika strategier för att lyckas med omställningsarbetet. Mina huvudsakliga slutsatser är att förändringsarbetet påverkas av kontakter med olika nätverk samt möjligheten att praktiskt prova en ny process och i betydligt mindre utsträckning av formellt ledningsarbete såsom miljöledningssystem.</p>

Företag kan behöva förändra sitt sätt att arbeta av flera olika skäl. Marknaden ställer krav på billigare lösningar med bibehållen kvalitet. Myndigheter ställer krav på större miljö­hänsyn. Syftet med den här uppsatsen är att granska tre olika företags förändringsarbete i samband med att RoHS-direktivet föreskrev att bly inte skall användas vid lödning. Ett företag har helt ställt om sin produktion, ett företag kör blandad produktion och ett av företagen endast en liten produktion med blyfritt eftersom dess kunder omfattas av de undantag som finns i direktivet. Undersök­ningen har utförts som kvalitativa intervjuer med miljö- och processansvariga på de olika före­tagen och visar att företagen haft olika strategier för att lyckas med omställningsarbetet. Mina huvudsakliga slutsatser är att förändringsarbetet påverkas av kontakter med olika nätverk samt möjligheten att praktiskt prova en ny process och i betydligt mindre utsträckning av formellt ledningsarbete såsom miljöledningssystem.

The theoretical part of dissertation is devoted to familiarization with the process of assembly and soldering of PCBs. There are described the selected types of lead-free solder paste, the various procedures of flux deposition, where the greater part is focuses to the printing through template. Also, I analyze the different procedures shouldering and soldering. I focused mainly on the mechanical mounting of SMD components soldering with help convection reflow and soldering in the vapor. In the practical part is described the design of the test PCB, methodology of assembly PCB and soldering various technologies with predefined settings. The analysis of the results is done by a non-destructive x-ray method and destructive micro-cut method. The x-ray method detects the position and size of the voids in the solder. This information is used for faster processing of micro-cut. The micro-cut method is included in the analysis for a more detailed examination of the solder joint. At the end of the thesis, there is a summary of the recommendation that the setting of the manufacturing process increases the quality of the brazed joint.

This diploma thesis aims to verify the properties of lead-free solders, which are subjected to accelerated aging by thermal cycling. The theoretical part describes in detail the most used lead-free solders and their characteristics. The next section describes fluxes and their important functions in the soldering process. Intermetallic compounds are also mentioned, which significantly affect the quality and service life of the soldered joint. In the practical parts, the test motif was on two different substrates - corundum ceramics and the widely used substrate FR-4 (Glass fiber fabric saturated with epoxy resin). SAC solder was chosen as the reference solder for the experiment, followed by solder containing bismuth (Sn42 / Bi58) and lead solder (Sn62 / Pb36 / Ag2). Accelerated aging by thermal cycling was performed in the temperature range from -20 ° C to 125 ° C, followed by performing a test of the mechanical strength of the soldered joint by means of a shear test. SnBi solder shows higher mechanical strength at the beginning of testing than SAC solder and lead solder, during temperature cycles, it significantly loses its mechanical properties, this is caused by increasing oxidation of the alloy. SAC solder seems to be promising, which has an almost constant decrease in mechanical strength during all temperature cycles on both corundum and FR-4 substrates.

Le besoin pressant de substitution du plomb dans les alliages de soudure a conduit à une introduction très rapide de nouveaux alliages sans plomb dont la connaissance en termes de comportement n'est pas assez approfondie. En effet, d'autres problématiques sont apparues (l'augmentation de la température du procédé de soudage, trop grand choix disponible dans les alliages alternatifs) alors que les problèmes relatifs aux alliages actuels sont restés sans réponse (le changement incessant de la microstructure des alliages de soudure, la méthodologie empirique prédisant la durée de vie). Tous les paramètres cités ci-dessus modifient la stabilité et la fiabilité des performances spécifiques de l'alliage de soudure et par conséquence, de tout le module électronique.De plus, avec la miniaturisation de l'électronique et les conditions d'environnement de plus en plus sévères, ces obstacles deviennent critiques et les solutions actuelles ne sont plus compatibles. Les demandes de ce marché deviennent donc de plus en plus strictes en termes de prédiction de durée de vie et de contrôle de fiabilité.L'objectif de ce projet est de comprendre et de concevoir une nouvelle formulation d'alliage sans plomb afin de développer une alternative à l'alliage plombé haute température et un alliage pour les applications haute fiabilité et en accord avec les directives gouvernementales. Des approches expérimentales avancées comme la nano-indentation, le suivi de l'évolution de la microstructure par SEM et par EDS mapping, l'étude des effets du vieillissement thermique sur la croissance de la taille des grains avec de la lumière croisée polarisée de microscopie optique etc seront utilisées pour développer un alliage sans plomb qui convienne aux exigences des applications automobile et pipeline / The urgent need for removing lead from solder alloys led to the very fast introduction of lead-free solder alloys without a deep knowledge of their behaviour. As a consequence, additional issues raised (increased thermally induced problems during soldering process, a too wide range of possible available alternative alloy formulations), while problems related to current solder alloys remained unsolved (the constant change of the solder alloy microstructure, empirical predicting lifetime methodology). All the above mentioned issues alter stability and reliability of the application specific performances of the solder alloy, and subsequently of the whole electronic module. These problems become critical and are no longer compatible, as the market goes towards miniaturization and harsh environment conditions. These market trends now require stricter life time prediction and reliability control. Objective of this project is to understand and design a novel lead-free solder formulation to develop a potential alternative to lead-based high temperature melting point solder for high reliability requirements and in accordance with governmental directives. An advanced experimental approach like nanoindentation, microstructure evolution with SEM and EDS mapping, thermal aging effects on continuous grain size growth with cross polarized light of optical microscopy etc. would be implemented to develop doped-SAC lead-free solders for the best-fit to requirements in automotives and pipelines applications