The integrity of interlayer bonding in asphalt pavements is a critical factor to ensure the structure behaves as a unified, monolithic system. Common issues like dust contamination on the receiving surface and inadequate tack coat application create weak interfacial planes that promote localized shear deformation specifically in high-traction zones like braking and turning areas. This study introduces a transferable framework that integrates lab-based interlayer bond characterization, composite fatigue testing, and finite element (FE) modeling to assess pavement performance under realistic field conditions.Two tack coats were used in this study, including regular tack coat (RSC-4) and clean tack coat (ILT-4) and considered 0%, 50% (remaining 50% was covered with dust), and 100% of the contact surface area, at three distinct tack coat application rates. Peak shear strength, initial stiffness, and fractured energy were determined from monotonic shear tests for quantifying bonding state and for FE simulations. Four-point bending (4PB) test was used to characterize fatigue performance, using normalized stiffness s(N), fatigue life and mid-life degradation rate or damage rate (DR). To relate the findings with field behavior, FE simulations estimate shear demand during braking, allowing a demand-to-capacity comparison. Results indicate that dust samples have 10%-30% lower bonding strength and must reach shear fail at the service life at the breaking zone with -0.93 midlife damage rate. Considering DR as a primary performance indicator, the framework provides the ultimate recommendations such as ensure surface cleanliness, uniform tack coat application, and quality control in high-stress zones.

Carbon fibers (CFs) are notable for their lightweight, high strength, and excellent electrical conductivity, making them promising for applications like electrical wiring. However, integrating CFs into copper-based wiring systems faces challenges, particularly regarding conductivity loss in fractured CFs. This article discusses a two-step experiment to enhance electrical and mechanical connection. Electrothermal-induced solvent evaporation (EISE) and meniscus-confined electrochemical deposition (MECD) were identified as effective methods for welding fractured CFs and were successfully implemented in open-air environment. Deposition of carbon nanotubes (CNTs) around the fiber improved conductivity by reducing fiber-tofiber contact resistance and creating a metal-like surface. Microstructural analysis and EDS analysis revealed that the CNT cladding exhibited high density and fewer irregularities and bulges in the joint area. Furthermore, the CNTs were tangled, forming a less organized structure compared to the original CF. In contrast, the Cu cladding exhibited paint-like coverage, significant irregularities, bulges, and cracks but maintained a small thickness. Electrical testing revealed that the average resistance of a single joined fiber decreased to resistance of 11.45 Ω and an electrical resistivity of 2.27 Ω/m, demonstrating improved electrical conductivity. Under optimal conditions, the joined fibers exhibited plastic fracture, and all joints showed improved performance except joint 1.e-g enhanced mechanical strength and stress tolerance.

A cold roll-bonding process using AA1050 and AA6061 sheets, in which the initial strain of AA1050 is higher than that of AA6061, was employed to fabricate an AA1050/AA6061 layered sheet. The sheet was then annealed at various temperatures ranging from 200 to 400 °C. The as-roll-bonded sheet exhibited a typical deformation structure in which the grains were elongated along the rolling direction. The evolution of the microstructure in the layered sheets varied significantly depending on the location, resulting in an inhomogeneous distribution of hardness along the thickness direction. After annealing up to 300 °C, both the AA1050 and AA6061 regions still mainly exhibited a deformed structure. Complete recrystallization occurred in the specimens annealed at temperatures above 350 °C. The hardness decreased with increasing annealing temperature in both AA1050 and AA6061, but the decrease was greater in the AA6061 region than in the AA1050 region. Resultantly, at 350 °C or higher, hardness was almost the same in all regions. The specimen annealed at 350 °C exhibited the best mechanical properties in terms of the balance between tensile strength and elongation. It is concluded that AA1050/AA6061 layered Al sheets with excellent mechanical properties can also be fabricated by CRB when AA1050 has a higher initial strain than AA6061, and subsequent annealing.

Through-silicon via (TSV) filling is indispensable for three-dimensional semiconductor packaging. Conventional processes rely on PVD (physical vapor deposition) or ALD (atomic layer deposition) seed layer deposition followed by copper electroplating, but these approaches face limitations in productivity and conformality. ALD and ELD (electroless deposition) have been investigated as seed-based approaches to overcome poor step coverage, while seedless strategies have also been proposed including additive-assisted electroplating, electroless alloy layers, metallic nanowires, and conductive pastes. These methods have demonstrated void-free or seam-free fills under specific conditions, yet challenges remain in achieving uniform superconformal filling across dense arrays, suppressing copper oxidation and interfacial contamination during rinsing/drying, and guaranteeing long-term reliability under thermomechanical cycling, electromigration, and humidity bias. In parallel, hybrid bonding has emerged as an alternative to thermo-compression bonding, where TSV filling performance, CMP (chemical mechanical polishing) planarization, and interface activation are crucial to reliable bonding. An integrated research approach incorporating both seed- and seedless-based TSV filling together with hybrid bonding provides a credible pathway to reliable three-dimensional stacking for high-bandwidth memory and artificial intelligence applications.

In order to confirm the optimal conditions for the LED(Light Emitting Diode) wire bonding process, the lead bump ball process optimization was analyzed. In the wire bonding process, it is an important process in which electrical characteristics operate by connecting the Au wire to the LED chip and lead frame. In the wire bonding method, various wire bonding processes, including thermocompression and ultrasonic bonding, were dealt with, and various variables affecting the lead bump ball process of wire bonding were analyzed through process variable analysis. Key variables for wire bonding working conditions were identified and optimized using the Response Surface Method(RSM) of Design of Experiments(DOE), the interaction between variables was confirmed through factor setting experiments, and the process was optimized using the RSM. This paper aims to improve the performance of the lead bump ball process by designing experiments with 5 factors at 3 levels and analyzing 4 response variables to find optimal conditions. It was confirmed that the performance of the lead bump ball process improved under optimized conditions, and as a result, optimal conditions that satisfied the targets for most reaction values, with the exception of ball diameter (BD), were secured.

A cold roll-bonding (CRB) process is applied to fabricate an AA1050/AA5052 layered sheet. In the process, commercial AA1050 and AA5052 sheets of 1 mm thickness, 40 mm width and 300 mm length are stacked onto each other, and then reduced to a thickness of 0.5 mm through a 2-pass cold rolling process without lubricant. The roll-bonded AA1050/AA5052 layered sheet is then annealed for 1 h at various temperatures from 200 to 400 °C. The specimens annealed at temperatures below 250 °C showed a typical deformation structure in which the grains were elongated along the rolling direction. However, the specimens annealed at temperatures higher than 300 °C exhibited recrystallization structures in both the AA1050 and AA5052 regions. All the roll-bonded and subsequently annealed specimens showed an inhomogeneous distribution of hardness in the thickness direction, in which the hardness in the AA5052 regions was higher than that in the AA1050 regions. As the annealing temperature increased, the tensile and yield strengths decreased and the elongation increased gradually. The mechanical properties were compared to those of commercial AA1050 and AA5052 materials and CRBed AA5052-2L materials from a previous study.

Automobiles are an essential means of transporting passengers and cargo, but traffic accidents are inevitable in their operation. These accidents can occur in various forms, such as front, rear, and side collisions. The resulting damage to the vehicle can also be seen similarly; it is inherently distinct: the complexity of repairing the car body makes a simple reliance on textbook knowledge insufficient. Successful correction of the damaged body largely depends on the experience of the practitioner. Discussions on body repair techniques should be based on empirical data reflecting current industry standards and associated costs. The variability of individual repair methodologies can result in significant time and financial expenditure in the field of automotive bodies. Application of new material technologies to vehicle fabrication requires continuous training and empirical research, especially on the body repair process involving new materials. In particular, since the left and right aprons and side members are made of different materials, such as aluminum and high-strength steel, careful restoration of these parts is required. Technical considerations are needed. Interest in safety and environmental impacts. In this study, SPR bonding technology analyzes experimental results.

Copper-coated carbon fibers have excellent conductivity and mechanical properties, making them a promising new lightweight functional material. One of the main challenges to their development is the poor affinity between carbon fiber and metals. This paper selects different carbon fibers for copper electroplating experiments to study the effect of carbon fiber properties on the interface bonding performance between the copper plating layer and carbon fibers. It has been found that the interfacial bonding performance between copper and carbon fiber is related to the degree of graphitization of carbon fiber. The lower the degree of graphitization of carbon fiber, the smaller the proportion of carbon atoms with sp2 hybrid structure in carbon fiber, the stronger the interfacial bonding ability between carbon fiber and copper coating. Therefore, carbon fiber with lower graphitization degree is conducive to reducing the falling off rate of copper coating and improving the quality of copper coating, and the conductivity of copper-plated carbon fibers increases with the decrease of graphitization degree of carbon fibers. The conductivity of copper-plated carbon fibers increases by more than six times when the graphitization degree of carbon fibers decreases by 23.9%. This work provides some benchmark importance for the preparation of highquality copper-plated carbon fibers.

The adhesive design of a fast steering mirror transmitting a high power laser is one of the important design elements that affect optical aberration of the mirror surface. In this paper, we designed the adhesive part to avoid the high power laser beam of the FSM system. Stiffness and wavefront error are trade-off relationships and an optical design was derived to maintain the wavefront error of the mirror surface at high temperatures while satisfying the bandwidth of the FSM system. For the optimal design of the mirror bonding position, structural analysis was conducted using ANSYS and wavefront error analysis was performed using Zernike polynomial code. Through those analysis, FSM most effective at an angle 60 degrees and a distance of 46mm.

Composite laminates are used in a wide range of applications including defense, automotive, aviation and aerospace, marine, wind energy, and recreational sporting goods. These composite beams still exhibit problems such as buckling, local deformations, and interlaminar delamination. To overcome these drawbacks, a novel viscoelastic autoclave bonding with tapered epoxy reinforcement polyurethane films is proposed. In existing laminates, compression face wrinkling and interlaminar delamination is caused in the sandwich beam. The unique viscoelastic autoclave spunbond interlayer bonding is designed to prevent face wrinkling and absorb and distribute stresses induced by external loads, thereby eliminating interlaminar delamination in the sandwich beam. Also, the existing special reinforcement causes stress concentrations, and the core is not effectively connected, which directly affects the stiffness of the beam. To address this, a novel tapered epoxy polyurethane reinforcement adhesive film is proposed, whose reinforcement thickness gradually tapers as it enters the core material. This minimizes stress concentrations at the interface, preventing excessive adhesive squeeze-out during the bonding process, and improves the stiffness of the beam. Results indicate the proposed model avoids the formation of micro cracks, interlaminar delamination, buckling, and local deformations, and effectively improves the stiffness of the beam.

In this study, we report the microstructural evolution and shear strength of an Sn-Sb alloy, used for die attach process as a solder layer of backside metal (BSM). The Sb content in the binary system was less than 1 at%. A chip with the Sn-Sb BSM was attached to a Ag plated Cu lead frame. The microstructure evolution was investigated after die bonding at 330 °C, die bonding and isothermal heat treatment at 330 °C for 5 min and wire bonding at 260 °C, respectively. At the interface between the chip and lead frame, Ni3Sn4 and Ag3Sn intermetallic compounds (IMCs) layers and pure Sn regions were confirmed after die bonding. When the isothermal heat treatment is conducted, pure Sn regions disappear at the interface because the Sn is consumed to form Ni3Sn4 and Ag3Sn IMCs. After the wire bonding process, the interface is composed of Ni3Sn4, Ag3Sn and (Ag,Cu)3Sn IMCs. The Sn-Sb BSM had a high maximum shear strength of 78.2 MPa, which is higher than the required specification of 6.2 MPa. In addition, it showed good wetting flow.

AA1050/AA6061/AA1050 layered sheet was fabricated by cold roll-bonding process and subsequently T4 and T6 aging-treated. Two commercial AA1050 sheets of 1 mm thickness and one AA6061 sheet of 2 mm thickness were stacked up so that an AA6061 sheet was located between two AA1050 sheets. After surface treatments such as degreasing and wire brushing, they were then roll-bonded to a thickness of 2 mm by cold rolling. The roll-bonded Al sheets were then processed by natural aging (T4) and artificial aging (T6) treatments. The as roll-bonded Al sheets showed a typical deformation structure, where the grains are elongated in the rolling direction. However, after the T4 and T6 aging treatments, the Al sheets had a recrystallized structure consisting of coarse grains in both the AA5052 and AA6061 regions with different grain sizes in each. In addition, the sheets showed an inhomogeneous hardness distribution in the thickness direction, with higher hardness in AA6061 than in AA1050 after the T4 and T6 age treatments. The tensile strength of the T6-treated specimen was higher than that of the T4-treated one. However, the strength-ductility balance was much better in the T4-treated specimen than the T6-treated one. The tensile properties of the Al sheets fabricated in the present study were compared with those in a previous study.

Changes in the microstructure and mechanical properties of as-roll-bonded AA6061/AA5052/AA1050 threelayered sheet with increasing annealing temperature were investigated in detail. The commercial AA6061, AA5052 and AA1050 sheets with 2 mm thickness were roll-bonded by multi-pass rolling at ambient temperature. The roll-bonded Al sheets were then annealed for 1 h at various temperatures from 200 to 400 °C. The specimens annealed up to 250 °C showed a typical deformation structure where the grains are elongated in the rolling direction in all regions. However, after annealing at 300 °C, while AA6061 and AA1050 regions still retained the deformation structure, but AA5052 region changed into complete recrystallization. For all the annealed materials, the fraction of high angle grain boundaries was lower than that of low angle grain boundaries. In addition, while the rolling texture of the {110}<112> and {123}<634> components strongly developed in the AA6061 and AA1050 regions, in the AA5052 region the recrystallization texture of the {100}<001> component developed. After annealing at 350 °C the recrystallization texture developed in all regions. The as-rolled material exhibited a relatively high tensile strength of 282 MPa and elongation of 18 %. However, the tensile strength decreased and the elongation increased gradually with the increase in annealing temperature. The changes in mechanical properties with increasing annealing temperature were compared with those of other three-layered Al sheets fabricated in previous studies.

본 연구에서는 GFRP(Glass Fiber Reinforced Polymer)를 주 보강근으로 사용하였으며, 정착길이가 없는 시험체를 제작 하여 4점 재하 휨시험을 수행하였다. 각 변수는 공칭지름이며 공칭지름 D13, D16, D19, 총 3가지의 변수로 이루어져있다. 휨 모 멘트는 공칭지름이 커질수록 약24.17%, 45.92% 강도가 증가하였으나 공칭 휨 강도를 고려하였을 때, 인장 강도와는 달리 공칭 지름에 비례하여 유사한 성능을 나타냄을 알 수 있었다. LVDT로 보강근과 콘크리트와의 부착성능을 확인하였고, 그 값은 매우 미미하며 거의 발생 되지 않은 것으로 판단된다. 또한 DIC로 시험체의 처짐을 확인하였으며, 실세 처짐 값과 유사함을 알 수 있었다.

As a filler metal for lowering the melting point of Ag, many alloy metal candidates have emerged, such as cadmium, with zinc, manganese, nickel, and titanium as active metals. However, since cadmium is known to be harmful to the human body, Cd-free filler metals are now mainly used. Still, no study has been conducted comparing the characteristics of joints prepared with and without cadmium. In addition, studies have yet to be conducted comparing the typical characteristics of brazing filler metals with special structures, and the joint characteristics of brazing filler metals with available frames. In this study, the characteristics of junctions of silver-based intercalation metals were compared based on the type of filler metal additives, using a special structure, a filler metal sandwich structure, to protect the internal base metal. The general filler metal was compared using the structure, and the thickness of the filler metal according to the thickness was reached. A comparison of the characteristics of the junction was conducted to identify the characteristics of an intersection of silver-based brazing filler metal and the effect on joint strength. Each filler metal’s collective tensile strength was measured, and the relationship between joint characteristics and tensile joint strength was explored. The junction was estimated through micro strength measurement, contact angle measurement with the base metal when the filler metal was melted, XRD image observation, composition analysis for each phase through SEM-EDS, and microstructure phase acquisition.

Cracks are an inevitable problem during the use of materials, and flexible sensors with self-healing capability are of great importance for applications in wearable devices and skin-like electronic devices. This paper prepared self-healing flexible strain sensors by compounding self-healing polyurethane with carbon nanotubes. First, by changing the ratio of disulfide bonds, a good balance between mechanical properties and self-healing efficiency was achieved in the prepared self-healing polyurethane. The most balanced sample reached 12.28 MPa in tensile strength, after 24 h of self-repair at 30 °C, the tensile strength was 7.75 MPa, and the self-repair efficiency was 63.11%; after 24 h of self-repair at 80 °C, the tensile strength was 11.64 MPa, and the self-repair efficiency reached 94.79%. Then the sensors prepared by compounding with carbon nanotubes showed a good electrochemical response, and both slow and fast repeated bending of the finger wearing the sensors yielded significantly different electrical signal changes, and the sensors were cut off and still had the same function after self-repair at 30 °C, demonstrating their excellent potential for applications in soft robots, wearable devices, etc.

As the time and cost of body repair can be greatly incurred due to differences in individual technologies, body repair technology should be discussed based on data on general working standards and costs, and as new material technology is applied to the body, continuous learning and experiment on vehicle body repair technology is essential. Since the left and right apron and side members with SPR bonding technology are made of different materials, aluminum and high-strength steel, the restoration of the left and right apron side members should be considered technically, as well as safety and environmental pollution. In this study, we experiment with heterogeneous apron and side members applied with SPR bonding and analyze the results.