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Purpose The purpose of this paper is to increase the reliability of manufactured electronics and to reveal reliability significant factors. The experiments were focused especially on the influence of the reflow oven parameters presented by a heating factor. Design/methodology/approach The shear strength of the surface mount device (SMD) resistors and their joint resistance were analyzed. The resistors were assembled with two Sn/Ag/Cu-based and one Bi-based solder pastes, and the analysis was done for several values of the heating factor and before and after isothermal aging. The measurement of thickness of intermetallic compounds was conducted on the micro-sections of the solder joints. Findings The shear strength of solder joints based on the Sn/Ag/Cu-based solder alloy started to decline after the heating factor reached the value of 500 s · K, whereas the shear strength of the solder alloy based on the Bi alloy (in the measured range) always increased with an increase in the heating factor. Also, the Bi-based solder joints showed shear strength increase after isothermal aging in contrast to Sn/Ag/Cu-based solder joints, which showed shear strength decrease. Originality/value The interpretation of the results of such a comprehensive measurement leads to a better understanding of the mutual relation between reliability and other technological parameters such as solder alloy type, surface finish and parameters of the soldering process.

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Abstract-There are many process variables, which more or less influence quality of a manufacturing process, and there are many parameters of a product, which constitute its quality. The control of variables of a manufacturing process for achievement of requested quality of a final product is a multi-parametric task. It is paid great effort to find such the way, which might lead to the most rapid solution. The use of full factorial experiments, fractional factorial experiments and Taguchi approach were compared from the point of view of number of experiments requested. It was found that the Taguchi orthogonal arrays are the most efficient method for higher number of process factors and that the full factorial experiments request the highest number of experiments from all methods under test.

Purpose -The purpose of this paper is to present a novel approach on investigating critical current densities in the solder joints of chip-size surface mounted device (SMD) components. The investigation involves a numerical approach and a physical validation with selected track-to-pad connections and high current loads (CXs). Design/methodology/approach -During the investigations, shape of solder fillets was calculated in Surface Evolver, and then the current densities were calculated accordingly in the given geometry. For the verification, CX tests were performed on joints at elevated temperatures. The joints were qualified with X-ray microscopy, cross-section analysis and shear tests. Findings -This study ascertained that the inhomogeneity in current density depends on the track-to-pad structure of the joint. Also this study found that the heavy CX decreases the mechanical strength, but the degradation does not reach the level of electromigration (EM)-induced voiding. Practical implications -The heavy CX significantly affects joint reliability and the results point out to EM-induced failure-limitations on printed circuit board (PCB)-based assemblies due to the thermomechanical weakness of the FR4 material. Originality/value -The experiments investigate current density from a novel aspect on more frequently used small-scale components with different track-to-pad configurationspointing out possible failure sources.