Purpose: The purpose of Part I of this paper is to investigate the influence of Bi additions on the surface tension, the interfacial tension, and the density of SnZn7Bi alloys (Bi=1 and 3 percent by mass) as a continuation of similar previous studies on Bi and Sb additions to the binary Sn‐Zn alloy. The main aim of Part I is to indicate that the lowering of the surface tension and interfacial tension is not sufficient for practical applications. However, knowledge of the interfacial tension between the soldering flux and the solder is necessary to convert the wetting force into the contact angle. This will be documented in Part II.Design/methodology/approach: The maximum bubble method was applied for the surface tension and the Miyazaki method was applied for the surface tension and the interfacial tension, using the density values from the dilatometric technique. The experimental surface tension results are compared with the Butler's thermodynamic modeling results and are discussed by means of the analysis of variance (ANOVA).Findings: On the basis of previous studies on Sn‐Zn‐Bi‐Sb alloys, the addition of Bi to SnZn7 slightly decreased the surface tension measured in an Ar+H₂atmosphere, similarly to the Butler's modeling results. Also, a similar slight decrease of the surface tension from the Miyazaki method measured in air and in nitrogen was observed, as well as a more significant lowering of the interfacial tension with the use of a flux in nitrogen. There was also a slight influence of the temperature on the numerical values of the surface tensions and the interfacial tension. In the ANOVA, taking into account the Bi content, the temperature of measurements, the atmosphere and the flux, the flux used was shown as the most important, and also, to a lesser extent, the atmosphere.Research limitations/implications: It is intended (the purpose of Part II of this paper) to verify the positive influence of Bi additions in SnZn7 alloys on the surface tensions and the interfacial tensions via the contact angles from the interaction with Cu on printed circuit board with different lead‐free finishes.Practical implications: It is suggested that further studies on more efficient fluxes are necessary for the practical application being in agreement with the ANOVA and the literature information.Originality/value: A slight improvement of the wettability with the use of Bi additions in the SnZn7Bi alloys in the course of various experimental techniques is proven, similar to results reported in various references. The obtained results will enlarge the SURDAT database of lead‐free soldering materials.

Purpose: The purpose of this study is to design and fabricate a simple passive sensor circuitry embedded into a printed circuit board (PCB) and then to examine its properties. Design/methodology/approach: A passive sensor transponder integrated circuit (IC) working in the high frequency (HF) 13.56 MHz frequency band was selected for this study. A loop antenna was designed to make the reported sensor circuitry readable. Next, the sensor circuitry was fabricated and embedded into a PCB with the proposed technologies. Finally, properties of the embedded structures were examined as well-functional parameters of the sensor circuitries. Findings: The described investigation results confirmed that the proposed technologies using an epoxy resin or standard materials used for PCB’s production allowed to successfully produce sensors embedded into PCBs. This technology did not have a negative significant impact either on quality of solder joints of the assembled transponder IC or on functional properties of the embedded sensor. Apart from the identification data, the reported sensor can provide information about a selected property of its environment, e.g. temperature when its internal temperature sensitive element is used or other factors with the use of external sensitive elements, such as humidity. Research limitations/implications: It is planned to carry on the reported investigations to examine other types of sensor circuitries capable of indicating e.g. humidity level and to evaluate influence of the proposed technology on their functional properties. Practical implications: The reported sensor circuitries can be successfully used in electronic industry in internet of things systems not only to identify monitored electronic devices, but also to control selected parameters of external environment. This creates opportunity to detect device malfunction by detecting local temperature growth or to analyze its environment, which might allow to predict failure of controlled products using radio waves. This advantage seems to be extremely beneficial for applications, such as space, aviation or military, in which embedded sensor systems may lead to enhancing reliability of electronic devices by reacting on occurred failures in a more efficient way. Originality/value: This study demonstrates valuable information for engineers conducting research on sensor components embedded into PCBs. The reported technologies are quite simple and cost-effective because of the use of standard materials known for PCB’s production or an epoxy resin which could be treated as an additional encapsulant material enhancing mechanical properties of the embedded sensor transponder IC.

The purpose of the experiment was to indicate which element of the production process of flexible printed circuit boards is optimal in terms of the reliability of final products. According to the Taguchi method, in the experiment, five factors with two levels each were chosen for the subsequent analysis. These included the number of conductive layers, the thickness of the laminate layer, the type of the laminate, the diameter of the plated holes, and the current density in the galvanic bath. The reliability of the PCBs in the produced variations was verified using the Interconnect Stress Test environmental test. The qualitatively best variant of the board construction was indicated using the signal-to-noise ratio and the analysis of variance method for each factor. The factors determined to be the most important in terms of reliability were the number of conductive layers and the current density in the galvanic bath. The optimal variant of the board construction was two conductive layers on a polyimide laminate, where the laminate layer was 100 μm thick, the hole diameter was equal to 0.4 mm, and current density was 2 A/dm² in the galvanic bath. Therefore, the plated experiment indicated the factors needed to obtain a high-quality product with a low failure rate.

The of miniaturization can be seen in electronics for some time already. The pinout of active components grows enabling them to have additional functions. The trend in usage of System in a Package (SiP) solutions is also evident thus routing of the active and passive elements became also challenging. To overcome this challenge boards with High Density Interconnection (HDI) where not only through hole, but also different kinds of microvias e.g. blind, buried, stacked, staggered via are used. The standard procedure to test reliability of boards and assemblies is very resource-hungry especially in time and money, as the tests have to be carried out in climatic chambers which lasts for weeks, followed by additional destructive testing like cross-sections. On the other hand IST (Interconnect Stress Testing) is a quick test, that enables to have assessment of the used technology especially the quality of the through holes of all types. Although the coupons are destroyed during the test, it is not necessary to test the manufactured circuits. This saves both materials and time. The technology optimizations and the key findings will be presented within the paper.

The purpose of the experiment was to indicate which element of the production process of flexible Printed Circuit Board is optimum in terms of the reliability of final products. According to the Taguchi method in the experiment five factors, two levels each, were chosen for the subsequent analysis. These include: the number of conductive layers, the thickness of the laminate layer, type of the laminate, the diameter of the plated holes, the current density in the galvanic bath. The reliability of the PCBs in produced variations was verified using the Interconnect Stress Test environmental test. The qualitatively best variant of the board construction was indicated using the signal-to-noise ratio and analysis of variance method for each factor. The factors that turned out to be the most important in terms of reliability are the number of conductive layers and the current density in the galvanic bath. The optimal variant of the board construction is two conductive layers, on a polyimide laminate, where laminate layer is 100 μm thick, hole diameter equal to 0.4 mm and current density of 2 A/dm2 in the galvanic bath. Therefore the plated experiment indicated factors needed to obtain a high-quality product with a low failure rate.

The increasing power density of modern electronic systems intensifies challenges related to heat dissipation and long-term reliability. Insulated metal substrates (IMS), particularly three-dimensional (3D), are increasingly used as integrated thermal–mechanical solutions in high-power electronics. However, their complex geometry and material interfaces introduce new reliability concerns, especially at solder joints. This study investigates the evolution of intermetallic compounds (IMCs) in solder joints formed on 3D aluminum IMSs with ENIG metallization, focusing on SAC305 and Sn42Bi57Ag1 solder alloys. Solder joints were subjected to environmental aging under high-temperature, high-humidity, and thermal-shock conditions to simulate realistic service environments. Microstructural and compositional analyses of the interfacial IMC layers were performed, together with measurements of IMC thickness evolution. The results show that aging significantly modifies the chemical composition and morphology of IMC layers in both solder systems. In SAC305 joints, progressive development of (Cu,Ni)₆Sn₅ phases with increasing Cu participation was observed. In Sn42Bi57Ag1 joints, Bi affected reaction kinetics but did not alter the diffusion-controlled nature of IMC growth. Thickness measurements indicate higher sensitivity of SAC305 joints to environment-assisted interfacial degradation, while Sn42Bi57Ag1 joints exhibit greater susceptibility to stress-assisted IMC growth during severe thermal cycling. These findings highlight the distinct reliability behaviors of tested solders on 3D IMSs and provide insight into their suitability for high-power electronic applications.