Aerosol jet printing (AJP) is a new non-contact direct writing technique designed to achieve precise and intricate patterns on various substrates. Specifically, the pneumatic AJP process breaks down the ink into fine particles, significantly reducing the risk of nozzle clogging and rendering it highly advantageous for industrial applications. This paper focuses on the optimization of the line electrode formation process using soluble silver clusters as the conductive ink, along with the aerosol formation procedure. The main parameters of the AJP process, namely sheath flow rate, atomizer flow rate, and dispensing speed, were identified and examined for their influence on line width and resistivity. Through this analysis, an operability window, including optimized conditions for printing high-quality lines using the AJP process, was established, along with a regression equation enabling the statistical estimation of line width. In summary, the outcomes of this investigation underscore the feasibility of an integrated printing system capable of precision control over line width, achieved through the optimization of AJP process parameters. Furthermore, it was established that pneumatic AJP offers robust process stability. The practical applicability of the proposed optimization techniques was assessed, highlighting their potential utilization in electrode formation processes within the electronic and display industry.

As the package integration density increases, the demand for reducing the bond wire length and lowering the wire loop height is constantly increasing. As the wire loop height decreases, the wire's stiffness increases, minimizing wire collapse during the molding process and preventing damage due to the exposed wire beyond the molding during the marking process. At the same time, the shorter length of the wire reduces the inductance and resistance of the interconnection, thereby improving electrical characteristics during high-power signal transmission. Various studies have been performed on the wire low loop profiles, but most of them are for ball bonding which is the dominant process for wire bonding. There are no studies on loop formation, loop profile according to bonding process parameters, and corresponding loop height formed by wedge bonding. Therefore, in this study, a method of forming an ultra-low loop using a 1 mm thick gold wire by comparing and analyzing loop formation was proposed. In addition, the characteristics of the loop height based on a parametric study of the wedge bonding process were analyzed for the application of a highly integrated package or high-power package.

Aerosol jet printing (AJP) is a new non-contact direct writing technique designed to achieve precise and intricate patterns on various substrates. Specifically, the pneumatic AJP process breaks down the ink into fine particles, significantly reducing the risk of nozzle clogging and rendering it highly advantageous for industrial applications. This paper focuses on the optimization of the line electrode formation process using soluble silver clusters as the conductive ink, along with the aerosol formation procedure. The main parameters of the AJP process, namely sheath flow rate, atomizer flow rate, and dispensing speed, were identified and examined for their influence on line width and resistivity. Through this analysis, an operability window, including optimized conditions for printing high-quality lines using the AJP process, was established, along with a regression equation enabling the statistical estimation of line width. In summary, the outcomes of this investigation underscore the feasibility of an integrated printing system capable of precision control over line width, achieved through the optimization of AJP process parameters. Furthermore, it was established that pneumatic AJP offers robust process stability. The practical applicability of the proposed optimization techniques was assessed, highlighting their potential utilization in electrode formation processes within the electronic and display industry.

As the package integration density increases, the demand for reducing the bond wire length and lowering the wire loop height is constantly increasing. As the wire loop height decreases, the wire's stiffness increases, minimizing wire collapse during the molding process and preventing damage due to the exposed wire beyond the molding during the marking process. At the same time, the shorter length of the wire reduces the inductance and resistance of the interconnection, thereby improving electrical characteristics during high-power signal transmission. Various studies have been performed on the wire low loop profiles, but most of them are for ball bonding which is the dominant process for wire bonding. There are no studies on loop formation, loop profile according to bonding process parameters, and corresponding loop height formed by wedge bonding. Therefore, in this study, a method of forming an ultra-low loop using a 1 mm thick gold wire by comparing and analyzing loop formation was proposed. In addition, the characteristics of the loop height based on a parametric study of the wedge bonding process were analyzed for the application of a highly integrated package or high-power package.

Stretchable-and-flexible-substrate-based systems have been focused as one of the next-generation applications of smart devices. The pre-stretched substrate implemented by buckled/wrinkled layers is widely used to enhance the stretchability and reliability of the system. At the same time, many different materials are tested to deal with large deformation for the substrate. However, most of the pre-stretched substrates can be stretched in uniaxial due to its nature of the wavy structure. Moreover, embedded rigid subcomponents on the substrate are severely affected and finally delaminated because of the excessive strain of the substrate. This study introduces a new concept of a hybrid stretchable substrate by combining two different regions into a single layer; rigid and soft regions. The soft region enables to stretch of the substrate in biaxial, while the rigid region offers a safe space for subcomponents to protect from the strain of the substrate. Two types of substrates of 40 mm x 40 mm and 150 mm x 120 mm were successfully fabricated. The hybrid substrate showed >20% uniaxial stretchability and >40% areal stretchability without failure. This hybrid substrate can be laminated with a pre-stretched substrate and/or used as a substrate for stretchable-and-flexible applications.

Mechanical testing methodologies are essential for advancing semiconductor packaging processes, ensuring the mechanical reliability of devices subjected to increasingly complex manufacturing processes and operational conditions. In recent years, advanced packaging technologies, including system-in-package (SiP) using 2.xD and 3D integration, have played a crucial role in enabling high-performance electronic devices. However, the miniaturization of device structures and integration of materials with mismatched thermomechanical properties have introduced significant mechanical challenges, including warpage, interfacial delamination, and fracture-induced failures. This review comprehensively evaluates key mechanical testing methodologies used to characterize the material properties and interfacial reliability of materials in semiconductor packages. Techniques such as the tensile test and double-cantilever beam (DCB) test are critically examined, with a focus on their effectiveness in assessing thin-film mechanical behavior, adhesion properties, and fracture mechanisms in miniaturized semiconductor structures. Furthermore, this review highlights the limitations of traditional testing techniques in micro- and nanoscale applications and explores emerging testing approaches. By providing a comparative analysis of mechanical testing techniques and their applications in semiconductor packaging, this work aims to provide insights for optimizing reliability evaluation strategies and guiding future developments in advanced packaging technologies.

Abstract Advancements in free‐form electronics demand robust bonding strategies for integrating ultra‐thin silicon dies onto non‐planar substrates. This study reports a compliant die attach process optimized for curved surfaces to achieve high surface conformity and minimal void formation. Bonding tools of varying materials and geometries [rigid/flat, rubber/flat, rigid/curved, and rubber/curved] are evaluated to assess their impact on bonding quality. Finite element method (FEM) simulations predicted stress distributions and contact mechanics, which are validated experimentally. Rubber/curved bonding tools exhibited superior compliance, resulting in uniform interfacial contact and reduced defect density. Process parameters such as bonding temperature, pressure, adhesive thickness, and annealing method are systematically refined. Integration of a pressure curing oven (PCO) enabled efficient gas evacuation and enhanced adhesive homogeneity. Distinct from prior approaches limited to planar or mildly curved substrates, this work addresses high‐curvature integration through a combined simulation–experiment framework. The proposed process achieved void‐free attachment with a curvature deviation below ±2.4% and a void ratio under 0.5% while maintaining mechanical integrity under thermal cycling. This framework provides a scalable and reliable platform for next‐generation curved electronics, with specific applicability to LiDAR modules and wide‐field of view (FoV) imaging systems.

Laser-based microchip transfer emerges as a promising solution, enabling high-speed and precise micro-LED panel production. This study investigates laser-induced micro-LED chip transfer, analyzing blister formation and transfer tendencies using NIR femtosecond and UV nanosecond pulse lasers.

Stretchability enables the device to be patched to a curved surface or to be folded several times to maximize usability. Among many methods, the pre-strain method is advantageous in that the stretchability as much as the pre-strain applied to the substrate is guaranteed even without material improvement. When the pre-strain is restored to its original state, the thin film gets wrinkled or the substrate gets buckled. Wrinkles and buckling that appear in this way are affected by the physical properties and dimensions of the substrate, and it is necessary to analyze their effect. In this study, a theoretical approach was used and a nonlinear post-buckling analysis was performed using a finite element method. The analysis was divided into two steps: the pre-strain step and the recovery step. According to the analysis results, it was possible to predict and analyze the wrinkle and buckling behavior due to pre-strain according to the physical properties and dimensions of the substrate. The pre-strain analysis method can be applied to multi-layer structures with three or more layers and can be used as a method to analyze wrinkle suppression and wrinkle shape control in future studies.

In this study, we developed a femtosecond pulse laser-based micro LED transfer process and optical system technology that precisely transfers micro LED chips with a size of several tens of micrometers. In order to realize the high-speed and precision transfer process of the micro LED chip, the femtosecond pulse laser was applied as a light source for the transfer process. In addition, dynamic release layer was applied to transfer micro LED chips at high speed without direct damages by laser. we analyzed the tendency of chip transfer process by adjusting the parameters for laser irradiation properties and material properties.