This diploma thesis deals with a defect detection with X-rays in the manufacturing procedure in the electrotechnical field. The work summarises the knowledge about technical possibilities of an X-ray device Cougar of YXlon company. Part of the work is focusing on scanning in 2D, 3D visualization and automatic analysis. The thesis describes inspection methods of a connector connection, the quality of a soldered joint and an encapsulated product.

Project is focused on describe modern assembly of microelectronic and electronic modules in electronic devices. Sense of the project is analyse reliability and inadequacies electronic devices assembled by modern technogies. Inadequacies modern technologies are impulse for design, implementation and testing new our way of assembly microelectronic modules. Main kind of materials which are used in this project are ceramics Al2O3 and printed circuit board FR4.

These thesis deals with electromigration in solder joint. In theoretical part are described lead-free solders, surface finish, formation of solder joint, intermetallic compounds a electromigration. In practical part is investigated a effect of electromigration on growth intermetallic compounds in solder jsoint.

This diploma thesis deals with the reliability of lead-free solder joints at a different interconnection structures. The first goal is to design the test cases shape BGA (FC) for testing the strength of lead-free solder joints at shear test in link with design of measuring method to detection shear strength during isothermal aging of lead-free solder joints. Following this shear stressing is investigating influence material and process compatibility, ie. pads finishing, material of solder and integrate of temperature (this mean thermal energy supplied during soldering) to lead-free solder joint strength.

This master´s thesis dealing with study of influence of inert atmosphere on the wettability of soldered surfaces. The theoretical part is discussed the issue of the soldering, solder joint, oxidation, and inert atmosphere. The glass cover with internal inert gas preheating for the wetting balance testing was prepared in the practical part. With this adjustment were realised tests, in which was examined the effect of the inert gases on the wettability of different materials combination. Further experiments were focused on plasma surface cleaning as possible flux substitution. The evaluation of these experiments were discussed in the end of this master´s thesis. Some of topics were designed for further experiments.

The diploma thesis deals with the sphere of solder joints reliability. The narrower focus is use of lead-free solder alloy SAC305 in the production process and parameters of its reliability. The text describes the main factors, which have the influence on the reliability of solder joints under conditions of thermal cycling. These factors also relate with choice of substrates and technological processes of preparation, which are characterized and described. Another part is devoted to estimating the reliability of soldered connections and are listed the fatigue model to estimate reliability. These fatigue models are categorized based on different physical mechanisms that operate in the soldered joints during operation. Based on the comparison of different models is selected the most appropriate model and in conjunction with simulation in ANSYS is estimated reliability. For this purpose is selected soldered connection of the FR-4 substrate and ceramic substrate via SMD component. They are manufactured test kits and subjected to conditions of temperature cycling. Results obtained from experimental measurements are compared with results obtained by simulation and calculation.

With the dramatic advances that have taken place in microelectronics over the past three decades, ball-grid array (BGA) packages are increasingly being used in microsystems applications. BGA packages with area-array configuration have several advantages: smaller footprint, faster signal transmission, testability, reworkability, handling easiness, etc. Although ceramic ball grid array (CBGA) packages have been used extensively in the microsystems industry, the use of plastic ball grid array (PBGA) packages is relatively new, especially for automotive and aerospace applications where harsh thermal conditions prevail. This thesis work has developed an experimental and a theoretical modeling program to study the reliability of two PBGA packages. The physics-based theoretical models take into consideration the time-dependent creep behavior through power law creep and time-independent plastic behavior through multi-linear kinematic hardening. In addition, unified viscoplastic constitutive models are also taken into consideration. The models employ two damage-metrics, namely inelastic strain and inelastic strain energy density, to predict the solder joint fatigue life. The theoretical predictions have been validated through air-to-air in-house thermal cycling tests carried out between 55 and #61616;C and 125 and #61616;C. In addition, laser-moir interferometry has been used to determine the displacement contours in a cross-section of the package at various temperatures. These contours measured through moir interferometry have also been used to validate the thermally-induced displacement contours, predicted by the models. Excellent agreement is seen between the experimental data and the theoretical predictions. In addition to life prediction, the models have been extended to map the field-use conditions with the accelerated thermal cycling conditions. Both linear and non-linear mapping techniques have been developed employing inelastic strain and strain energy density as the damage metric. It is shown through this research that the symmetric MIL-STD accelerated thermal cycles, currently in practice in industry, have to be modified to account for the higher percentage of creep deformation experienced by the solder joints in the field-use conditions. Design guidelines have been developed for such modifications in the accelerated thermal cycles.

Current board technologies are inherently performance-limited (FR-4) or cost-prohibitive (Al2O3/AlN). Next-generation high-density packaging applications would necessitate a new base substrate material to achieve ultra-fine pitch solder-joint reliability and multiple layers of fine-line wiring at low cost. The NEMI 2000 roadmap defines the need for 4-8 layers of 5-10 m wiring for future system boards. The 2003 ITRS roadmap calls for organic substrates with less than 100-m area-array pitch in the package or board by year 2010. Solder-joint reliability at such fine-pitch is a matter of concern for the industry. Use of underfills reduces thermal stresses but increases cost and, in addition, their dispensing becomes increasingly more complicated with the shorter gaps required for future interconnects. Therefore, there is a pronounced need to evaluate board materials with CTE close to that of Si for reliable flip-chip on board without underfill. Recently, a novel manufacturing process (using polymeric precursor) has been demonstrated to yield boards that have the advantages of organic boards in terms of large-area processability and machinability at potentially low-cost while retaining the high stiffness (~250 GPa) and Si-matched CTE (~2.5 ppm/㩠of ceramics. This work reports the evaluation of novel SiC-based ceramic composite board material for ultra-fine pitch solder-joint reliability without underfill and multilayer support. FE models were generated to model the behavior of flip-chips assembled without underfill and subjected to accelerated thermal cycling. These models were used to calculate solder-joint strains which have a strong direct influence on fatigue life of the solder. Multilayer structures were also simulated for thermal shock testing so as to assess via strains for microvia reliability. Via-pad misregistration was derived from the models and compared for different boards. Experiments were done to assemble flip-chips on boards without underfill followed by thermal shock testing so as to get the number of cycles to failure. To assess microvia reliability, 2 layer structures containing vias of different diameters were fabricated and subjected to thermal cycling. Via-pad misalignment was also studied experimentally. Modeling and experimental results were corroborated so as to evaluate thermomechanical suitability of C-SiC for high-density packaging requirements.

This research aims to understand the reliability of Sn-Ag-Cu solder interconnects used in plastic ball grid array (PBGA) packages using microstructure evolution, laser moiré interferometry and finite-element modeling. A particle coarsening based microstructure evolution of the solder joint material during thermal excursions was studied for extended periods of time lasting for several months. The microstructure evolution and particle coarsening was quantified, and acceleration factors were determined between benign field-use conditions and accelerated thermal cycling (ATC) conditions for PBGA packages with different form factors and for two different lead-free solder alloys. A new technique using laser moiré interferometry was developed to assess the deformation behavior of Sn-Ag-Cu based solder joints during thermal excursions. This technique can used to estimate the fatigue life of solder joints quickly in a matter of few days instead of months and can be extended to cover a wide range of temperature regimes. Finite-element analysis (FEA) in conjunction with experimental data from the ATC for different lead-free PBGA packages was used to develop a fatigue life model that can be used to predict solder joint fatigue life for any PBGA package. The proposed model will be able to predict the mean number of cycles required for crack initiation and crack growth rate in a solder joint.

L’étude s’inscrit dans le cadre d’un projet Européen 3Dice, dont l’objectif est d’améliorer la fiabilité mécanique d’un composant microélectronique innovant. La miniaturisation du composant induit des difficultés lors de la caractérisation mécanique. Le développement de méthodes de caractérisation est nécessaire. La flexibilité du composant microélectronique est de plus en plus demandée. Les joints de connexion subissent souvent un pré-chargement. La tolérance du joint aux pré-chargements est intéressante à étudier. Cette thèse s’est déroulée autour de ces deux problématiques. Les méthodes de caractérisation de la couche mince métallique, la résine chargée en silice et le joint de connexion sont développées. L’étude de la fatigue du joint de connexion est effectuée. / This work is a part of an European fund project ‘3Dice’ which aims to improve the mechanical reliability of an innovated microelectronic product. The miniaturization of microelectronic component causes the difficulties to determine mechanical properties of materials involved. The development of experimental methods for microelectronic materials’ characterization is necessary. The flexibility of the products is an additional requirement recently in microelectronic field. The solder joint’s tolerance to the pre-load is interesting to investigate. The thesis is carried out based on these two topics. The characterization methods of thin film, resin with fillers and solder joint are developed. The fatigue behavior of solder joint is investigated under different displacement ratios.