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The thermal cycling life of direct bonded aluminum (DBA) and active metal brazing (AMB) substrates with two types of plating—Ni electroplating and Ni–P electroless plating—was evaluated by thermal shock tests between −50 and 250 °C. AMB substrates with Al2O3 and AlN fractured only after 10 cycles, but with Si3N4 ceramic, they retained good thermal stability even beyond 1000 cycles, regardless of the metallization type. The Ni layer on the surviving AMB substrates with Si3N4 was not damaged, while a crack occurred in the Ni–P layer. For DBA substrates, fracture did not occur up to 1000 cycles for all kind of ceramics. On the other hand, the Ni–P layer was roughened and cracked according to the severe deformation of the aluminum layer, while the Ni layer was not damaged after thermal shock tests. In addition, the deformation mechanism of an Al plate on a ceramic substrate was investigated both by microstructural observation and finite element method (FEM) simulation, which confirmed that grain boundary sliding was a key factor in the severe deformation of the Al layer that resulted in the cracking of the Ni–P layer. The fracture suppression in the Ni layer on DBA/AMB substrates can be attributed to its ductility and higher strength compared with those of Ni–P plating.

Chemical plating has recently been employed for the preparation of flexible piezoresistive sensors; however, plating solutions and processes that affect the sensitivity still need further exploration. In the study, a sponge-based flexible sensor with copper as its conductive material is prepared using electroless plating. The variation in sponge resistance and sensitivity changes with different plating times are studied. It is found that, with the increasing plating time, the conductivity increases and the resistance of sample will decrease. Moreover, the range of resistance difference will decrease under compression, thus the sensitivity decreases. Furthermore, the sensor’s applications were assessed, verifying the practicability of the developed preparation method. This study may bring ideas for the new development of flexible pressure sensors.

In order to make the Polyimide (PI) film material have good surface conductivity and meet its application in aerospace fields, for example, radar antenna, in this paper, the highly chemically inert PI material on the surface was modified by alkaline etching, and the metal layer on the surface of PI film was then deposited by electroless copper plating technology, to give PI good surface conductivity and meet its application in aerospace fields, for example, radar antenna. The microstructure and properties of surface metal layer of PI film before and after surface modification were characterized by SEM, contact angle tester and resistance tester. After alkaline etching at room temperature, there is a staggered and evenly distributed protrusion structure with dendritic and rivet structures on the surface of PI. However, the PI film surface etched at 60 °C presents pits with different sizes and depths of etching holes, and the hydrophilicity of the PI film surface is enhanced after etching. The coating on the PI is uniform and dense, and has good conductivity. This research realizes the preparation of high conductivity and high bonding force metal layer on the surface of PI film under alkaline etching, which provides technical support for the application of polyimide in aerospace fields.

In this study, we developed a novel cerium/ascorbic acid/iodine active species to design a redox flow battery (RFB), in which the cerium nitrate hexahydrate [Ce(NO3)3·6H2O] was used as a positive Ce3+/Ce4+ ion pair, and the potassium iodate (KIO3) containing ascorbic acid was used as a negative I2/I− ion pair. In order to improve the electrochemical activity and to avoid cross-contamination of the redox pair ions, the electroless plating and sol–gel method were applied to modify the carbon paper electrode and the Nafion 117 membrane. The electrocatalytic and electrochemical properties of the composite electrode using methanesulfonic acid as a supporting electrolyte were assessed using the cyclic voltammetry (CV) test. The results showed that the Ce (III)/Ce (IV) active species presented a symmetric oxidation/reduction current ratio (1.09) on the C–TiO2–PdO composite electrode. Adding a constant amount of ascorbic acid to the iodine solution led to a good reversible oxidation/reduction reaction. Therefore, a novel Ce/ascorbic acid/I RFB was developed with C–TiO2–PdO composite electrodes and modified Nafion 117–SiO2–SO3H membrane using the staggered-type flow channel, of which the energy efficiency (EE%) can reach about 72%. The Ce/ascorbic acid/I active species can greatly reduce the electrolyte cost compared to the all-vanadium redox flow battery system, and it therefore has greater development potential.

Advanced electronic devices are supposed to highly integrated, such as wearable electronics, bioelectronics, and light-emitting diodes. The circuits are required to be fabricated compactly to the structure. This study proposed an approach to achieve close fabrication of circuit and structure. We used digital light processing additive manufacturing to rapidly form substrate structure, which is composed of ultraviolet-curable resin and Cu2(OH)PO4 particle. The substrate structure was then processed by laser activation and electroless plating metallization. As a result, the selective circuit can be fabricated on the surface of substrate structure. A series of characterizations were conducted using SEM, XPS, CLSM, and so on to investigate the morphology and analyze the surface chemistry of composite. After 5 min electroless copper plating, the resistivity of copper circuit on composite were 7.5 × 10−8 Ω·m. The obtained copper layer has good adhesion property (highest 5B level after adhesion test). This work provides an approach for complex structures of circuit and structure integrated devices, which has a potential application in advanced electronic devices.

Electroless nickel plating is a suitable technology for the hydrogen industry because electroless nickel can be mass-produced at a low cost. Investigating in a complex environment where hydrogen permeation and friction/wear work simultaneously is necessary to apply it to hydrogen valves for hydrogen fuel cell vehicles. In this research, the effects of hydrogen permeation on the mechanical characteristics of electroless nickel-plated free-cutting steel (SUM 24L) were investigated. Due to the inherent characteristics of electroless nickel plating, the damage (cracks and delamination of grain) and micro-particles by hydrogen permeation were clearly observed at the grain boundaries and triple junctions. In particular, the cracks grew from grain boundary toward the intergranualr. This is because the grain boundaries and triple junctions are hydrogen permeation pathways and increasing area of the hydrogen partial pressure. As a result, its surface roughness increased by a maximum of two times, and its hardness and adhesion strength decreased by hydrogen permeation. In particular, hydrogen permeation increased the friction coefficient of the electroless nickel-plated layer, and the damage caused by adhesive wear was significantly greater, increasing the wear depth by up to 5.7 times. This is believed to be due to the decreasing in wear resistance of the electroless nickel plating layer damaged by hydrogen permeation. Nevertheless, the Vickers hardness and the friction coefficient of the electroless nickel plating layer were improved by about 3 and 5.6 times, respectively, compared with those of the free-cutting steel. In particular, the electroless nickel-plated specimens with hydrogen embrittlement exhibited significantly better mechanical characteristics and wear resistance than the free-cutting steel.

The development of Li-ion battery cases requires superior electrical conductivity, strength, and corrosion resistance for both cathode and anode to enhance safety and performance. Among the various battery case materials, super duplex stainless steel (SDSS), which is composed of austenite and ferrite as two-phase stainless steel, exhibits outstanding strength and corrosion resistance. However, stainless steel, which is an iron-based material, tends to have lower electrical conductivity. Nevertheless, nickel-plating SDSS can achieve excellent electrical conductivity, making it suitable for Li-ion battery cases. Therefore, this study analysed the plating behaviour of SDSS plates after nickel plating to leverage their exceptional strength and corrosion resistance. Electroless Ni plating was performed to analyse the plating behaviour, and the plating behaviour was studied with reference to different plating durations. Heat treatment was conducted at 1000 °C for one hour, followed by cooling at 50 °C/s. Post-heat treatment, the analysis of phases was executed using FE-SEM, EDS, and EPMA. Electroless Ni plating was performed at 60–300 s. The plating duration after the heat treatment was up to 300 s, and the behaviour of the materials was observed using FE-SEM. The phase analysis concerning different plating durations was conducted using XRD. Post-heat treatment, the precipitated secondary phases in SAF2507 were identified as Sigma, Chi, and CrN, approximating a 13% distribution. During the electroless Ni plating, the secondary phase exhibited a plating rate equivalent to that of ferrite, entirely plating at around 180 s. Further increments in plating time displayed growth of the plating layer from the austenite direction towards the ferrite, accompanied by a reduced influence from the substrate. Despite the differences in composition, both the secondary phase and austenite demonstrated comparable plating rates, showing that electroless Ni plating on SDSS was primarily influenced by the substrate, a finding which was primarily confirmed through phase analysis.

The ultraprecision machining of the mold surface is important because the performance of optical components produced using optical injection is related to the surface roughness and shape precision of the mold core. To process hard-to-cut mold core materials such as stainless steel, electroless nickel-phosphorus (NiP) plating is applied to the surface of the substrate, and ultraprecision processing is performed on the plating surface using diamond turning (DT) and magnetorheological finishing (MRF). Although MRF processing can remove tool marks caused by diamond turning and improve shape accuracy, it suffers from poor processability for NiP. In this paper, an ultraprecision processing method with a heat treatment process was presented to improve the MRF processability of electroless NiP. The plating was heat-treated under each condition and subjected to DT processing followed by MRF. The surface roughness and reflectance were measured and evaluated after processing. As a result, the surface roughness of NiP subjected to a 1-h heat treatment at 450 °C significantly decreased from Ra 7.0 nm to Ra 1.5 nm when compared to the specimen that did not undergo any heat treatment. An improvement in surface roughness confirmed that reflectance improved by more than 9% and 18%, respectively, compared to that for the diamond-turned and non-heat-treated specimen. These results confirmed that the MRF performance was improved through the NiP heat treatment process and contributed to quality improvements in ultraprecision injection optical parts. Furthermore, this technology can be applicable to various fields that used NiP plating, including the manufacturing of metal reflectors in the visible and ultraviolet regions.

As a method to mitigate fouling at the venturi flowmeter of pressurized water reactors, electroless nickel-phosphorus (Ni–P) plating and palladium (Pd) plating were conducted on AISI 304L stainless steel specimens and evaluated through a series of performance tests, including static corrosion testing, adhesion testing, and water loop testing using mock-up venturis. As expected from the zeta potentials, no iron oxide particles deposited on the surface of the plated specimens. The Ni-plated specimens exhibited localized corrosion, whereas the minimum oxidation was observed on the Pd-plated specimens. The water loop tests showed consistent results with the static corrosion testing. The adhesion forces after a four-month corrosion test were similar to those before. The overall performance tests indicated that electroless Pd plating on the inner surfaces of venturis could be a viable solution for mitigating fouling in pressurized water reactors.

Voids in electroless copper (Cu) plating layers critically influence the reliability of microvias in high-density interconnect (HDI) packaging substrates. This study investigates void formation mechanisms by fabricating multilayered Cu structures that simulate microvia interconnections and performing electroless Cu plating under controlled nickel (Ni) ion concentrations and bath temperatures. Void morphology and distribution are analyzed using transmission electron microscopy (TEM) and quantitative image analysis. The results reveal that increased Ni content and elevated bath temperatures accelerate the plating rate, thereby promoting void formation at the initial stage of deposition. Theoretical analysis suggests that this behavior is driven by surface cohesion forces acting on nascent voids. A void growth mechanism is proposed, wherein voids predominantly originate within the initial Cu layer due to localized hydrogen accumulation near palladium (Pd) catalysts. In contrast, subsequent layers—deposited after Pd sites are buried—exhibit reduced maximum (max.) void sizes and lower void fractions. These findings provide mechanistic insight into void evolution in electroless Cu layers and underscore the critical role of Ni content and bath temperature in enhancing HDI packaging substrate reliability.