Field Emission Electron Probe Microanalysis Research Articles

The Effect of Homogenization Heat Treatment on 316L Stainless Steel Cast Billet.

This investigation aims to analyze the effect of homogenization heat treatment at 1240 °C for 2 and 6 h on the hardness, distribution, morphology, and chemical composition of the δ-ferrite and sigma phases in 316L stainless steel cast billet. A field emission scanning electron microscope, combined with electron back-scattered diffraction, a field emission electron probe microanalyzer with a wavelength dispersive spectrometer, and a Vickers microhardness tester are applied to identify various phase evolutions in the cast billet. The morphology of the δ-ferrite and sigma phases in the austenite matrix of the 316L cast billet are strongly related to the subsequent hot and cold wire drawings. The homogenization heat treatment is expected to provide a driving force to form spheroid interdendritic δ-ferrite and to minimize the amount of the brittle sigma intermetallic compound in the austenite matrix. The homogenization heat treatment at 1240 °C effectively spheroidized all δ-ferrites into blunt ones in the cast billet. The transformation of δ-ferrite into sigma is dominated by temperature and cooling rate. The fast air cooling after homogenization between 1240 and 850 °C retards the precipitation of the sigma in the δ-ferrite. There are two δ-ferrite transformation mechanisms in this experiment. The direct transformation of the δ-ferrite into sigma is observed in the as-cast 316L stainless steel billet. In contrast, the eutectoid transformation of the δ-ferrite into the sigma and austenite dominates the 316L cast billet homogenized at 1240 °C, with a slow furnace cooling rate.

Study on the passivation effect and corrosion mechanism of an environmentally protective insulating coating on non-oriented electrical steel

In this study, we successfully developed three insulating coatings for non-oriented electrical steel. These coatings were composed of phosphate film-forming agents, passivating agents (vanadate, cerium nitrate, and zirconate), and polyurethane dispersants. The surface morphology, composition, electrochemical properties, and corrosion resistance of the three coatings were characterized using scanning electron microscopy (SEM), field-emission electron probe microanalyzer (EPMA), confocal Raman microscopy (CRM), scanning vibration electrode technology (SVET), electrochemical testing, and neutral salt spray experiments. The passivating agent substantially enhanced the compactness of the coating by forming a composite film with the phosphate film-forming agent, which prevented direct contact between the matrix and the corrosive medium and significantly improved the corrosion resistance of the coating. The zirconate passivator significantly increased the compactness of the coating, forming a composite film composed of continuous three-dimensional metals or metalloid oxides on the matrix surface, thereby providing a good shielding effect for the substrate. The incorporation of polyurethane increased fluidity and formed a cross-liked network structure with the composite coatings, enhancing corrosion resistance. The overall properties of the coating that had a zirconate passivator (TZB) demonstrated the best performance among the three systems, surpassing industrial standards, and fulfilling the application requirements for non-oriented electrical steel.

One-Step Fabrication of the ZnO/g-C3N4 Composite for Visible Light-Responsive Photocatalytic Degradation of Bisphenol E in Aqueous Solution.

The ZnO/g-C3N4 composite was successfully synthesized by a simple one-step calcination of a urea and zinc acetate mixture. The photocatalytic activity of the synthesized composite was evaluated in the degradation of bisphenol E (BPE). The morphology, crystallinity, optical properties, and composition of the synthesized composite were characterized by using various analytical techniques such as scanning electron microscopy (SEM), transmitted electron microscopy (TEM), field emission-electron probe microanalysis (FE-EPMA), nitrogen adsorption and desorption isotherm measurement, Fourier-transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The degradation rate of BPE with the ZnO/g-C3N4 composite was 8 times larger than that obtained with pure g-C3N4 at the optimal conditions. The excellent photocatalytic activity was attributed to the synergistic effect between the g-C3N4 and ZnO, which enhanced the efficiency of charge separations, reduced the e-/h+ pairs recombination, and increased the visible light absorption ability. The radical scavenger studies indicated that the •O2 - and h+ species were mainly responsible for the degradation of BPE. The stability test suggested the chemical and photostability of the synthesized composite. Two possible photocatalytical mechanisms have been suggested.

Nanostructure and nanoindentation study of pulse electric-current sintered TiB2–SiC–Cf composite

A carbon-fiber (Cf) doped TiB2–SiC composite was prepared and investigated to determine its densification behavior, micro/nanostructural properties, and mechanical characteristics. TiB2–25 vol% SiC–2 wt% Cf was prepared at 40 MPa and 1800 °C for 7 min using the pulsed electric-current sintering technique, and a relative density of 98.5% was realized. The as-sintered composite was characterized using advanced techniques, e.g., X-ray diffractometry, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, field-emission electron probe micro-analysis, and nanoindentation. The Cf additive could remove the surface oxide layers from the TiB2 and SiC domains, thus transforming them into TiB2 and SiC. According to micro/nanostructural studies, Cf could not retain its initial structure and was eventually converted into graphite nanosheets. In addition, the prepared composite was examined using the nanoindentation technique, and the following results were obtained for the calculated hardness, elastic modulus, and stiffness values: TiB2 > SiC > TiB2/SiC interface.

Effect of controlled cooling process on the atmospheric corrosion behaviour of HRB400E hot rolled rebar

To address the problem of rusting of reinforcing bars that occurs in industry, the aim is to control the denseness of the iron oxide skin by changing the controlled cooling process without increasing the production cost, thereby improving the corrosion resistance of the bars. In this paper, the effect of different cooling control processes on the industrial atmospheric corrosion behaviour of HRB400E hot-rolled rebar was investigated using alternating wet and dry corrosion tests. The morphology and structure of iron oxide on the surface and cross-section of the rebar were observed using scanning electron microscopy (SEM) and field emission electron probe microanalysis (EPMA); the corrosion products and electrochemical behaviour of the specimens after alternating wet and dry tests were compared using x-ray diffraction analysis (XRD) and electrochemical methods. The results showed that the hot-rolled rebar without controlled cooling had a dense surface, a thicker iron oxide skin and a tighter bond between the iron oxide skin and the substrate; the corrosion rate of the hot-rolled rebar without controlled cooling was less than that of the rebar with controlled cooling in the alternating wet and dry corrosion tests; the corrosion products mainly consisted of α-FeOOH, γ-FeOOH and Fe3O4; the self-corrosion potential and rust layer resistance of the hot rolled rebar without controlled cooling after rolling are higher than those of the controlled cooling bars, showing good corrosion resistance.

Interface instability of SiCf-reinforced superalloy matrix composites

A number of recent reports indicate that SiCf-reinforced superalloy matrix composites show promise for increasing mechanical properties and lowering density. However, this has not yet been successfully demonstrated. The essence is the severe interfacial reaction. In present study, Ni, Fe, Co, Cr, Mo, 80Ni20Cr, 80Ni20Mo, 80Mo20Ni (in wt%), and Waspaloy-SiCf systems were fabricated. Interfacial reactions were analyzed by optical microscopy, field emission scanning electron microscopy and electron probe microanalysis. The results indicate that superalloy matrix elements Ni, Fe, and Co react violently with SiC, whereas strengthening elements Cr, and Mo, react mildly. Addition of other elements to form alloying systems including 80Ni20Cr, 80Ni20Mo, 80Mo20Ni and Waspaloy-SiCf fail to effectively suppress the severe reaction. Alloying could not suppress the reaction completely both in thermodynamic and kinetic. Matrix elements Ni, Fe, and Co dominate the reaction. Hence, the interface between superalloy and SiC fiber exhibits instability.

A Comparative Study on Microstructure and Properties of Ultra-High-Speed Laser Cladding and Traditional Laser Cladding of Inconel625 Coatings.

In this study, ultra-high-speed laser cladding (UHSLC) and traditional low-speed laser cladding (LSLC) were employed to prepare high-quality Inconel625 coatings on 27SiMn substrates. UHSLC has cladding speeds of 30 m/min, which are 15 times faster than those of LSLC, and it produces a much greater cladding efficiency, which is 13.9 times greater than LSLC. The microstructure of the Inconel625 coatings was investigated in detail utilizing field emission scanning electron microscopy (FESEM) and electron probe microanalyzer (EPMA). According to the FESEM results, UHSLC Inconel625 coatings have more refined crystals than LSLC Inconel625 coatings. Nevertheless, the EPMA results indicate that the UHSLC Inconel625 coatings exhibit much more severe elemental segregation. Moreover, the hardness, wear and corrosion resistance of Inconel625 coatings are significantly enhanced by increasing the laser cladding speed. Furthermore, the reasons for the differences in microstructure and properties of Inconel625 coatings prepared by UHSLC and LSLC were clarified by finite element simulation. UHSLC technique is, therefore, more suitable for preparing Inconel625 coatings on 27SiMn steel surfaces than LSLC.

Wear resistance performance of high entropy alloy–ceramic coating composites synthesized via a novel combined process

Titanium nitride (TiN), characterized by its high hardness and strength, was widely used as ceramic coating to improve the wear resistance of matrix materials. In this work, AlCrFeNiTix high-entropy alloy (HEA) powders were synthesized by direct electrochemical reduction in molten salt from the mixed metal oxides. Then, TiN ceramic coating on the AlCrFeNiTix bulk HEA containing the topologically close-packed (TCP) phase (σ phase, Laves phase, and Ti3Al phase) was prepared by vacuum hot pressing sintering, where nitride element come from boron nitride parting agent sprayed on the graphite mold. The effect of titanium content on the crystal structure, microstructure, hardness, and wear resistance of the products were investigated by X-ray diffraction, field emission scanning electron microscope, field emission electron-probe microanalysis, Vickers hardness tester, and friction–abrasion testing machine. The bulk HEAs exhibit excellent hardness and its hardness increases significantly with the increase of titanium content. The wear mechanism changes from both of predominantly delamination and accompanied oxidative wear to single delamination wear, which is due to ultra-high melting point and high hot hardness of TiN, that can effectively prevent the oxidation and deformation of the worn surface. Formation of the ceramic coatings containing the TiN second phase and TCP phase are the key factor to AlCrFeNiTix alloy with the excellent hardness and wear properties.

Microstructural and nanoindentation study of TaN incorporated ZrB2 and ZrB2–SiC ceramics

This study assessed the sinterability and microstructure of ZrB2-SiC-TaN and ZrB2-TaN ceramics. Spark plasma sintering at 2000 °C and 30 MPa for 5 min produced both ceramics. The relative density of ZrB2 ceramic containing TaN was 95.3%; the addition of SiC increased this value to 98.1%. SiC’s contribution to the elimination of ZrB2 surface oxides was the primary factor in the advancement of densification. The in situ formation of hexagonal boron nitride at the interface of TaN and ZrB2 was confirmed by high-resolution transmission electron microscopy, field emission-electron probe microanalyzer, X-ray diffractometry, and field emission scanning electron microscopy. Moreover, the in situ graphite might be produced as a byproduct of the SiC-SiO2 process, hence boosting the reduction of oxide compounds in the ternary system. The SiC compound had the highest hardness (29 ± 3 GPa), while the ZrB2/TaN interface exhibited the greatest values of elastic modulus (473 ± 26 GPa) and stiffness (0.76 ± 0.13 mN/nm).

Compressive strength modeling and validation of cenosphere-reinforced aluminum–magnesium-matrix-based syntactic foams

Al–Mg-matrix-based syntactic foams were manufactured using stir-casting methods. The concentration of Mg in the Al–Mg matrix and the matrix hardness and lattice parameters decreased with increasing cenosphere volume fraction. The lattice parameters were calculated using field-emission electron probe microanalysis (FE-EPMA) and Redlich–Kister polynomials, and high-resolution X-ray diffraction was conducted to determine the changes in the matrix mechanical properties. A prediction model was proposed to estimate the foam compressive strengths under quasistatic conditions, demonstrating better agreement with the experimental data than previous models.

A novel approach for selective flotation separation of chalcopyrite and molybdenite – Electrocatalytic oxidation pretreatment and its mechanism

Electrocatalytic oxidation was adopted as a novel pretreatment method for the following selective flotation separation of chalcopyrite and molybdenite. Flotation tests of single mineral and artificial mixed ores were performed after the pretreatment of electrocatalytic oxidation, and surface analysis of the both minerals before and after the pretreatment was characterized by water contact angle, zeta potential, X-ray photoelectron spectroscopy (XPS) and field emission electron probe microanalyzer (EMPA) measurements. Flotation results showed that molybdenite could be efficient separated from chalcopyrite in the artificial mixed ores regardless of the mass ratio. Surface analysis showed that chalcopyrite was strongly depressed due to the hydrophilic oxidation products (e.g., CuO, Cu(OH)2, FeOOH and Fe2(SO4)3) were formed and precipitated on its surface after the pretreatment of EO, sharply reducing its floatability. However, the water contact angles of molybdenite surface changed hardly attributed to the rapid dissolution of oxidation products (e.g., MoO42− and SO42−) into the pulp under alkaline condition, making it keep good floatability. A highly efficient flotation separation of chalcopyrite and molybdenite was obtained via the pretreatment of electrocatalytic oxidation. Therefore, electrocatalytic oxidation pretreatment can be employed as a promising alternative for the toxic depressants of copper sulfides.

Size effects on IMC growth of Cu/Ni/Sn-3.5Ag microbump joints during isothermal aging and prediction of shear strength using ANN

Significant downsizing trend is currently directing the advanced microelectronic packaging industry, which poses new challenges to the manufacturing process and reliability of high-density chip interconnections. In this paper, to investigate the size effect of microbump joints on the interfacial structure and bonding strength, the chip-to-chip bonding joints fabricated by microbumps of same Cu/Ni/Sn-3.5Ag construction but of various sizes were experimentally examined. After thermocompression bonding process to fabricate the chip-to-chip microbump interconnections, the intermetallic compound (IMC) growth on the Ni/Sn-3.5Ag interface during 150 °C isothermal aging was compared for joints of 100, 40 and 25 μm in diameter as well as 35, 25 and 15 μm in solder layer height, using field emission electron microscopy and electron probe microanalysis. A clear size effect on the thickness and morphology of Ni3Sn4 IMC was observed, showing thicker IMC in joints of smaller diameter and lower height. The Ni concentration distribution in the solder layer was verified to be dependent on the joint size, with possible reasons being enhanced sidewall diffusion and grain boundary diffusion through IMC grains in small-diametered joints, as well as shorter diffusion path in lower joints. The shear strength of chip-to-chip bonding vehicles was also found to be size-dependent. In addition, artificial neural network (ANN) approach was applied to establish the numerical correlation of structural factors and bonding strength. It was found that a properly constructed ANN model can successfully predict the influence of the complex combinations of geometric and interfacial factors with highly accurate output, providing an effective tool for design and optimization of microbump interconnection structures and processes.

Study on Application of Class C Fly Ash for RCC dam in Nam Ngiep 1 Hydropower Project in Lao PDR

The Nam Ngiep 1 (NNP1) Hydropower Project in Lao PDR has constructed a 167 m-high roller compacted concrete (RCC) dam. Class C fly ash (FA) procured from the Mae Moh coal-fired power plant in Thailand has been selected as a supplemental cementitious material for the NNP1 RCC dam, to control hydration heat generation and improve workability. Though rarely used globally for RCC, it was found that the Class C FA was acceptable for the NNP1 RCC because it did not undergo a large temperature rise in its early age and because of the relatively high compressive strength of the concrete as the age in the medium-term and long-term as compared with general features of the concrete with Class C FA. To clarify the reaction mechanism for Class C FA, factors affecting the above features of Class C FA are analyzed and evaluated by observing FA particles and concrete core specimens of NNP1 RCC through a variety of devices, including Field Emission-Electron Probe Micro Analysis (FE-EPMA). This paper clarifies the reaction mechanism of the concrete with Class C FA and demonstrates its applicability for RCC dam and other structures.

An interfacial survey on microstructure of ZrB2-based ceramics codoped with carbon fibers and SiC whiskers

The objective of this paper was to study the impact of carbon fiber (Cf) addition on the densification behavior and the microstructure formation of ZrB2 reinforced with SiC whiskers (SiCw). The spark plasma sintering (SPS) performed at 1900 °C led to a near fully dense composite as a result of the synergetic effect between SiCw and Cf on the sintering behavior of ZrB2. The field emission scanning electron microscopy (FESEM), field emission electron probe micro-analyzer (FEEPMA), and X-ray diffraction (XRD) analyses verified the unreactivity of the ZrB2-SiCw-Cf system under the applied sintering conditions. The thermodynamic study proposed the in-situ generation of B4C and ZrC compounds, although any proof could be found in neither X-ray photoelectron spectroscopy (XPS) patterns nor high-resolution transmission electron microscopy (HRTEM) images. Additionally, thanks to the nucleation and growth of new SiC and graphite phases, barely any whisker/fiber form of such additives could be observed in the micrographs. Many dislocations, originating from the plastic deformation during the SPS process and the mismatch between the thermal expansion coefficients of adjacent phases, were found in the microstructure.

Thermodynamic parameters, microstructure, and electrochemical properties of equiatomic TiMoVWCr and TiMoVNbZr high-entropy alloys prepared by vacuum arc remelting

This study investigated the thermodynamic parameters, microstructures and electrochemical properties of TiMoVWCr and TiMoVNbZr bio-refractory high-entropy alloys (bio-RHEAs) prepared using the vacuum arc remelting process. The alloys were characterized using field emission scanning electron microscopy, field emission electron probe microanalyzer, X-ray diffraction analysis, and potentiodynamic polarization tests. The determined thermodynamic values of Ω-parameter, atomic size difference and valence electron concentration for the TiMoVWCr and TiMoVNbZr bio-RHEAs were within the range of solid solution formation. A high-temperature stable single BCC1 phase was obtained using the thermodynamic equilibrium calculations for the TiMoVWCr and TiMoVNbZr systems. The TiMoVWCr alloy microstructure comprised a dendrite, an inter-dendrite, and a second phase, while TiMoVNbZr alloy comprised a dendrite and an inter-dendrite. The TiMoVWCr alloy forming the stable single body-centered cubic solid solution demonstrated homogeneous microstructure and high phase stability. Moreover, pitting resistances of TiMoVWCr and TiMoVNbZr bio-RHEAs were remarkably superior to that of ASTM F75 alloy.

Characterization of TiC ceramics with SiC and/or WC additives using electron microscopy and electron probe micro-analysis

This investigation aimed to assess the discrete and synergic impacts of SiC whiskers (SiCw) and nano-sized WC (WCn) on the microstructure of TiC-based materials. Three dense specimens of TiC−3 wt% WCn, TiC−30 vol% SiCw, and TiC−30 vol% SiCw−3 wt% WCn were yielded using the spark plasma sintering (SPS). The X-ray diffraction patterns (XRD), as well as the microstructural observations, suggested unreactive sintering processes; however, thermodynamic studies showed that some minor chemical interactions could take place, leading to surface oxide removal. Furthermore, the field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) micrographs, as well as the field emission electron probe micro-analyzer (FEEPMA) images, proved the WCn dissolution into the TiC matrix, forming (Ti,W)C solid solution in the TiC-WCn and TiC-SiCw-WCn ceramics, and also the graphite precipitation from the TiC in all samples. Glassy SiO2 phase, available as the surface oxide of starting SiCw or produced as the in-situ phase, could form some amorphous interfaces in the relevant composites.

A New Constraint on the Physicochemical Condition of Mars Surface during the Amazonian Epoch Based on Chemical Speciation for Secondary Minerals in Martian Nakhlites

Iddingsite in Martian nakhlites contains various secondary minerals that reflect water–rock interaction on Mars. However, the formation processes of secondary Fe minerals in iddingsite are unclear because they include carbonates precipitated under reductive and alkaline conditions and sulfates that are generally precipitated under oxidative and acidic conditions. Mineral types cannot coexist under equilibrium. Herein, we characterize the carbonate phase of meteorite Yamato 000593 as siderite and Mn-bearing siderite via field-emission electron probe microanalyzer (FE-EPMA). Then, we examined the distribution and speciation of trace Cr and S within the carbonates through synchrotron micro-focused X-ray fluorescence-X-ray absorption fine structure and scanning transmission X-ray microscopy (μ-XRF-XAFS/STXM) analysis to estimate the transition history of Eh-pH conditions during siderite formation to explain the coexistence of carbonate and sulfate phases in the nakhlite vein. Specifically, the distribution and speciation of S in the mesostasis and carbonate phases and the heterogeneous distribution of Mn-FeCO3 incorporating Cr(III) in the carbonate constrain the Eh-pH condition. The conditions and transition of the fluid chemistry determined herein based on speciation of various elements provide a new constraint on the physicochemical condition of the water that altered the nakhlite body during the Amazonian epoch.

A Study on the Microstructure and Corrosion Characteristics of Early Iron Age Bronze Mirrors Excavated from the Korean Peninsula

Bronze mirrors, considered important grave goods, were widely used before glass mirrors in ancient times. Most excavated bronze artifacts are covered with corrosive materials and lose their original colors. More importantly, identifying corrosion characteristics and the manufacturing techniques used for these artifacts are essential for proper artifact preservation. In this study, Early Iron Age bronze mirrors excavated from the Korean Peninsula were examined to determine their microstructures, corrosion characteristics, and production techniques using various analytical methods, such as Micro-Raman spectroscopy and field emission electron probe microanalysis. As a result, sulfides containing iron suggested chalcopyrite use during production or that the sulfides originated from copper, iron, and sulfur residual matte. The analysis also detected corrosion layers with high tin oxide (SnO2) levels and selective corrosion in the α + δ eutectoid phase on the artifact’s surface. In the corrosive layer, cuprite, malachite, and cassiterite corrosion products were detected, and nanocrystalline SnO2 was identified as a characteristic of long-term soil erosion. Identifying these artifacts’ corrosion characteristics and manufacturing techniques is essential and can greatly contribute to proper artifact preservation.

Combined role of SiC whiskers and graphene nano-platelets on the microstructure of spark plasma sintered ZrB2 ceramics

This research explores the sintering behavior and microstructure of ZrB2-based materials containing graphene nano-platelets (GNPs) and SiC whiskers (SiCw). Spark plasma sintering (SPS) process at 1900 °C was implemented to sinter the specimen, leading to a composite with 100% relative density. High-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), field emission-electron probe microanalyzer (FE-EPMA), and high-resolution X-ray diffractometry (HRXRD) were employed to study the SPSed sample, along with the thermodynamics predictions. According to the HRXRD result and microstructural observations, the sintering process was non-reactive, which was endorsed with the XPS analysis. Furthermore, graphene presented a beneficial role for eradicating the oxide impurities in the sample during the sintering. Such oxide impurities were reduced to the original phases of SiC and ZrB2, contributing to porosity removal. Nanostructural investigations revealed the formation of ultrathin amorphous interfaces (~10 nm) between ZrB2/graphene phases, disordered atomic planes in graphene platelets, and dislocations in ZrB2 grains. One reason for generating crystalline defects in the microstructure was found out to be the mismatches amongst the elastic properties of the available compounds in the system.

Enhancement of bonding strength in BiTe-based thermoelectric modules by electroless nickel, electroless palladium, and immersion gold surface modification

In this study, an electroless nickel (EN), electroless palladium (EP), and immersion gold (IG) (ENEPIG) multilayer coat was developed for application on BiTe-based thermoelectric materials to increase the bonding strength between BiTe-based materials and Cu electrodes in thermoelectric modules. The ENEPIG-plated thermoelectric module exhibited a bonding strength of over 11 MPa, which was approximately 40% higher than those of conventional EN-plated modules. According to the interfacial analysis of the bonding areas via a field emission electron probe micro analyzer (FE-EPMA), the Ni layers in ENEPIG and EN acted as diffusion barriers to inhibit the formation of brittle Sn-Te intermetallic compounds (IMCs). Sn-Cu-Pd and Sn-Cu IMCs were formed below the Ni-plated area at the bonding interface of the ENEPIG and EN-plated modules, respectively. However, Sn-Cu-Pd IMCs in the ENEPIG interface exhibited thicker and more homogeneous IMC layers after heat treatment compared to the Sn-Cu IMCs in the conventional EN interface. The wettability of the ENEPIG-plated BiTe surface was significantly greater than that of the EN-plated surface. This directly induced fewer and smaller pores on the bonding interface of the BiTe-based materials with ENEPIG plating compared to those with EN plating, thereby resulting in the higher bonding strength of ENEPIG-plated modules.