Coated Copper Substrate Research Articles

Effect of Ni Addtion on Electroless Cu for High Density Interconnect PCB Substrate

Introduction Nowadays, high-density interconnect (HDI) printed circuit board (PCB) substrates have been widely applied to high-end electronics to meet the increasing input and output (I/O) density and small footprint area. Micro-via, a tiny structure buried among build-up layers that provide electrical interconnection is a key component in the HDI substrate. However, the preparation of micro-via is facing new challenges. It is not only required that the size of the micro-via scales down to meet the increased interconnect density, but also that the micro-via should withstand severe operating conditions in different scenarios. Therefore, it is of great importance to improve the quality of micro-vias during processing and manufacturing. The micro-via structure is a sandwich structure that is processed by electroless Cu plating and Cu electrolyte plating sequentially, and thus the quality of the electroless Cu layer can significantly affect the reliability of micro-via. In this work, we mainly focused on the electroless Cu plating process and investigated the effect of the electroless Cu deposition speed on the quality of the micro-via structure. SIM and HR-TEM characterizations were employed to investigate the micro-structure inside the electroless Cu layer. Materials and Method In this study, we used the common alkaline ion catalyst method to prepare the electroless Cu layer. The electroless Cu plating and electrolyte Cu plating was conducted on a PCB Resin Coated Copper (RCC) substrate that was cleaned by soft etching in an acid condition. The surface is then pre-dipped in an anionic solution, and palladium ions were adsorbed using an alkaline ion catalyst. The electroless Cu processes adopted in a reaction bath that consists of Cu resource (CuSO4·5H2O), complexing agent (KNaC4H4O6·4H2O) and reductant (HCHO). The whole reaction was conducted in the alkaline condition with a PH of 12.5, and the thickness of the electroless Cu deposition was controlled at around 0.20 µm. NiSO4 is selected as the Ni precursor to alter the Ni concentration in the reation bath. The contents of Ni addition were selected as 50 %, 100 %, 200 % and 300% of a conventional process at a bath temperature of 27 ºC. The thickness of the plated Cu layer was measured by a gravimetric method. Results and discussion TEM observation was used to identify the structure at the interface. Fig. 1 shows the TEM observation of the sample with 50 % and 200 % Ni concentrate. There are some nanovoids found at the interface between the Cu substrate and electroless Cu, which is arguably due to hydrogen generated during electroless Cu plating. The sample with a higher reaction speed has more nanovoids. It can be due to that the higher reaction speed can generate more hydrogen bubbles in the bath that can attach to the electroless Cu layer, leading to nanovoids as shown in Fig. 1. The samples prepared at different bath temperatures are under investigation to illustrate that the reaction speed can significantly affect the Cu electroless layer quality. Conclusions In this work, we investigated the Ni effect in electroless Cu on the RCC substrate. It is found that the higher Ni incorporation can lead to massive nanovoids generation and fine Cu grains in the electroless layer, which is a potential risk for the reliability of the HDI substrate. By reducing the Ni incorporation content, the number of nanovoids can be effectively reduced. Figure 1

Fabrication of Si Anode for Enhancing Electrochemical Performance by Electrodeposition Method

Silicon (Si) is one of the most abundant elements in the earth's crust and is important for the development of semiconductors, solar cells, and lithium ion battery (LIB)electrodes. silicon nanomaterials-based device production is currently hampered by high prices, high material consumption, and very sophisticated procedures of film deposition, including chemical vapour deposition (CVD) and plasma-enhanced chemical vapour deposition (PE-CVD).Future demand will need the development of cost-effective, simple, and high-throughput deposition techniques.moreover A large-scale use of Si anodes in LIB is hindered primarily by two factors: (a) a significant volume change (about 300%) during discharging and (b) the deterioration of silicon after several charging and discharging cycles. By covering silicon nanostructures with carbon nanomaterials that also improve the electrochemical performance of LIBs, these disadvantages may be eliminated. In order to meet all of these requirements, the electrodeposition approach may provide the means to create Si thin films in an aesthetic way. We studied We used water-contaminated BMImTf2N to electrolyze SiNPs on Graphene (Grn) -coated copper substrates at room temperature.SiNPs average 70-90 nanometres (nm). Grn layer on the Cu substrate enhances Si nucleation and prevents oxidation. At 0.5C, the charge capacity was 1350 mAh g-1 and the discharge capacity was 1588 mAh g-1. The columbic process's efficiency increased from 85% to 97% after 100 cycles. Grn's conductivity and volume expansion will boost Si's cycle life. Figure 1

Pool Boiling of CNT + GO Nanomaterial–Coated Copper Substrate: An Experimental Study

Abstract Nanoparticle coating on copper substrates like carbon nanotubes (CNT) and graphene oxide (GO) is a promising method to enhance the surface properties as well as improve the boiling heat transfer characteristics. The main objective of the present investigation is to study the influence of the nanocomposite coating on the performance of pool boiling heat transfer. CNT + GO nanomaterials are coated on copper substrates via the dip coating method by varying the concentration of the nanomaterial. Morphological analysis, surface roughness, and wettability behavior of the coating are also observed. The result shows that CNT + GO increases the surface roughness of the samples, and the coated samples are superhydrophilic in nature. Compared with the uncoated sample, the coated sample shows the maximum increase in critical heat flux and heat transfer coefficient is 145.76% and 259.08%, respectively. A high-speed camera is used to study the bubble dynamics. Bubble diameter, departure frequency, and site density are also calculated and presented.

Ag-CuO/epoxy hybrid nanocomposites as anti-corrosive coating and self-cleaning on copper substrate

This study aims to prepare Ag-CuO nanoparticles and assess their efficiency in protecting the copper substrate. The prepared Ag-CuO nanoparticle was characterized using, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope/energy-dispersive X-ray (SEM/EDX), and transmission electron microscope (TEM). The anticorrosion performance of the epoxy coatings containing various weight percentages of Ag-CuO nanoparticles was evaluated in 3.5 wt% NaCl solution using potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) techniques. The results showed that corrosion potential shifted from − 0.211 V for uncoated copper to − 0.120 V for 5.0 wt% Ag-CuO/epoxy hybrid nanocomposite. Electrochemical measurements indicated that the coating 5.0 wt% coating exhibited excellent inhibiting properties with an efficiency of 99.9%. Wettability and mechanical properties were measured for both uncoated and coated copper substrates. The contact angle for 5.0 wt% coating is equal to 104° enhancing the hydrophobic character of the surface. The study clearly establishes that the hybrid composite has a significant potential for protecting the copper substrate.

Mobile sealing and repairing of damaged ceramic coatings by powder aerosol deposition at room temperature

Repair instead of discard is going to be crucial in the vision of a green future, therefore we propose the powder aerosol deposition (PAD) as a promising technique to reprocess ceramic coatings at room temperature. Alumina coated copper substrates with an artificial imperfection are manufactured in a first step. In a second step, the repair of this imperfection is carried out using two different PAD apparatuses: first, a conventional PAD apparatus with a moving substrate holder and a converging slit nozzle and second, a miniaturized μPAD apparatus with a fixed substrate holder and a circular de-Laval nozzle. The different film profiles are studied using a laser scanning confocal microscope. Cross-sectional images to investigate the microstructure are taken by a scanning electron microscope. Finally, samples of both PAD apparatuses are exposed to an oxidizing atmosphere at 400 °C proving the gas-tightness as a further quality feature of the repair coating.

A Nickel Coated Copper Substrate as a Hydrogen Evolution Catalyst

Replacing precious metals with low-cost metals is the best solution for large scale production. Copper is known for its excellent conductivity and thermal management applications. When it comes to hydrogen evolution reaction, it is highly unstable, especially in KOH solution. In this paper, we approached a simple method to reduce corrosion and improve the performance by depositing nickel-molybdenum oxide and nickel on copper substrates and the achieved tafel slopes of 115 mV/dec and 117 mV/dec at 10 mA/cm2. While at first, molybdenum oxide coated samples showed better performance after 100 cycles of stability tests, the onset potential rapidly changed. Cu-Ni, which was deposited using the electron gun evaporation (e-gun), has shown better performance with 0.28 V at 10 mA/cm2 and led to stability after 100 cycles. Our results show that when copper is alloyed with nickel, it acts as a promising hydrogen evolution reaction (HER) catalyst.

Drop cast coating of leather dye on copper and investigation of its corrosion behavior in sodium chloride solutions

The copper (Cu) is used in many heat exchange, electrical and electronics applications for its good thermal and electrical conductivity. In addition, copper have other attractive properties like corrosion resistant and antibacterial properties. However, these properties of copper can be vanished upon its corrosion in aggressive chloride environments. The present work report corrosion behavior of black leather dye (LBD) coated copper substrates in 0.5 M NaCl. The coating of copper has been done by drop casting. The investigation is carried out through UV–visible spectroscopy (UVS), Fourier transform infrared spectroscopy (FTIR), open circuit potential curves (OCP), electrochemical impedance spectroscopy (EIS), Tafel polarization curves (TPC) and optical microscopy (OM). EIS and TPC propose that LBD coated Cu perform better than bare copper substrates in NaCl solutions. The OM results are in accordance with the fact that coating has been successfully formed on copper substrates and protective in nature. In the view of obtained results, LBD is recommended for corrosion prevention of Cu in NaCl.

Atomic Level Insight into Wetting and Structure of Ag Droplet on Graphene Coated Copper Substrate-Molecular Dynamics versus Experiment.

Understanding the atomic-level phenomena occurring upon the wetting of graphene-coated Cu with liquid Ag is pivotal for the description of the wetting phenomenon and the role of graphene as a diffusion barrier. We have performed molecular dynamics (MD) simulations and confronted with our present experimental results to characterize wetting behavior of graphene coated Cu surfaces. Perfect and defected graphene layers covering Cu surface were wetted with liquid Ag droplet at 1273 K. Structural and topological aspects are discussed to characterize structure of the liquid Ag droplet and a product of wetting reaction occurring on Cu/Gn and Cu/Gndef substrates, also including perfect graphene layer and a pure Cu surface. The obtained results reveal the importance of defects in graphene structure, which play a key role in wetting mechanism and the formation of AgCu alloy. As a consequence, we observe a change of the wetting behavior and topology of both bulk and adsorbed Ag atoms by using Voronoi analysis (VA). Despite the differences in time scale, atomistic simulations allowed us to catch the early stages of wetting, which are important for explaining the final stage of wetting delivered from experiment. Our findings reveal also graphene translucency to metal-metal interactions, observed in previous papers.

Nucleate pool boiling heat transfer enhancement in saturated Novec 7100 using titanium dioxide nanotube arrays

The effect of titanium dioxide (TiO2) nanotubes on pool boiling heat transfer is experimentally investigated. Four surfaces including plain or nanotube coated copper or titanium substrates are tested in the saturated Novec 7100. Both the nanotube coated surfaces enhances the critical heat flux (CHF) at around 40% compared to the relative plain surfaces. The nanotube coated titanium substrate effectively improves the heat transfer coefficient at around 65% over the plain surface, while the nanotube coated copper substrate shows the average heat transfer coefficient at about 20% lower than its plain surface. From the coincident boiling curves after reducing a thermal interface resistance from the nanotube coated copper substrate and bubble departure characteristics of the two coated surfaces, it is inferred that the nanotubes are effective in enhancing both the heat transfer coefficient and CHF. The observation shows both the improvements of the nanotube surfaces could be attributed to the modified bubble dynamics and effective rewetting of the dry spots, related to the faster liquid replenishment due to capillary wicking of the tube-like structure. The identification of the TiO2 nanotube influence on pool boiling with the dielectric fluids can help the further applications of the nanotube coating in two-phase cooling systems.

Electrodeposition of silicon nanospheres on rGO coated copper substrate for lithium-ion batteries

In the present work, the electrodeposition of silicon nanospheres was carried out from water contaminated room temperature ionic liquid medium on the reduced graphene oxide (rGO) coated copper (Cu) substrates. The graphene oxide coated copper was reduced in hydrogen: argon mixture to obtained rGO coated copper substrate which was used for electrodeposition of silicon nanospheres. The silicon nanospheres were electrodeposited using 1 M SiCl4 in water contaminated 1-Butyl-3-Methylimidazolium-bis (Trifluoromethylsulfonyl) imide (BMImTf2N) ionic liquid at −1.5 V (vs. Pt). The X-ray diffraction (XRD) patterns at 44.8˚, 51.42˚, 75.12˚, and Raman peak at 521 cm−1 confirm the deposition of elemental silicon. The field emission scanning electron microscopy (FE-SEM) images show the electrodeposited silicon nanospheres of average particle size 125 nm. Further, the electrochemical measurements were carried out to explore the performance of the active material as a negative electrode in Li-ion batteries. The reversible specific capacity of electrodeposited Si nanospheres is obtained as 294 mAhg−1 at current density 250 µA cm−2.

Fabrication of superhydrophobic, self-cleaning and anti-icing ZnO/PTFE-SiO2 nano-composite thin film

In the present study, we have been using a two-step process to create a super-hydrophobic property on the copper surface. We first created micro and nano-scale roughness by applying ZnO layers on the copper surface, then immersion the samples in a PTFE-SiO2 suspension at specific times to reduce the surface energy. We also investigated the effect of silica nanoparticle concentrations, ZnO layer numbers and sample immersion time in the PTFE-SiO2 suspension on the surface hydrophobicity. The morphology and chemical analysis of the coating surface were studied with Field Emission Scanning Electron Microscopy (FESEM) and Infrared Fourier Transform Spectroscopy (FTIR) methods. The water contact angles on the prepared samples were measured by a water contact angle analyzer method. Icing tests were performed at a constant operating temperature of −8 °C. Also, the self-cleaning behavior of the samples was evaluated by an iron oxide powder. The results indicated that the ZnO/PTFE-SiO2 coated copper substrate showed superhydrophobic (CA, 164°), anti-icing (icing time 700 s) and self-cleaning properties.

Multi-wall carbon nanotubes coating on a copper substrate using airbrush spray coating

The spray coating technique is used in this study to spread a thin layer of nanoparticle on a large flat substrate. The proposed spray coating techniques has a great potential for large scale productions, as these techniques have no restrictions on the substrate size and low utilization of the process parameters. In this study, a simple airbrush spray coating technique is used to deposit the multiwall carbon nanotubes (MWCNTs) on copper substrates with a decent deposition control. The microstructures, surface roughness, and wettability of the coated substrates were tested and compared with the pure copper substrates. The MWCNTs coated copper substrates exhibits a significant enhancement of the mechanical properties compared to the normal surface. The thickness of the copper substrates increases with increase in coating weight concentrations, the maximum thickness 1.43 microns achieved at 0.4 wt. % of MWCNTs. The usage of copper and MWCNTs based thin film signifies a inspiring but possibly a sustaining chance for developing the future generation heat transfer materials

Switching of heating and cooling modes using thermal radiation films

We study emissivity (ε)-dependent radiative heat transfer phenomena in remote and contact configurations. To demonstrate the emissivity-dependent radiative heating mode in a remote configuration, we fabricated miniature greenhouses covered with low (0.34)- and high-ε (0.86) polyethylene films and monitored temperatures on the floors, insides, and covers of the greenhouses during 24 h. The high-ε greenhouse yielded a 9-°C increase in floor temperature relative to the low-ε greenhouse at a one-sun solar irradiance because the high-ε film effectively trapped floor radiation. In contrast, the cover temperature remained lower in the high-ε greenhouse due to intensified radiation released from the high-ε film. This self-cooling effect was more evident when an emissive film was in physical contact with an object. While bare copper heated up to 55 °C, a high-ε film coated copper substrate was kept cooler by 4 and 2 °C compared with the bare and low-ε film coated copper samples, respectively.

Hafnium carbide based solar absorber coatings with high spectral selectivity

Single layer coatings of hafnium carbide were deposited on stainless steel, copper and silicon substrates by means of reactive sputtering. The deposition process was optimized for maximum solar absorptance by varying the process parameters. In the case of coated stainless steel substrates, we obtained a maximum solar absorptance of 0.925 along with a thermal emittance of 0.13. For coated copper substrates we obtained a maximum solar absorptance of 0.948 along with a thermal emittance of 0.03. Reflectance spectra of SS and Cu substrates coated at optimized parameters were measured in the wavelength range 250 nm to 20 µm. Detailed x-ray photoelectron spectroscopy (XPS) studies were carried out to investigate the chemical composition of the coatings. XPS analysis of coated samples showed that because of the tendency of HfC to oxidize, the coating had a surface consisting mostly of HfO2 but the extent of oxidation reduced with depth and partially oxidized HfC was present on the subsurface layers of the coatings. Along with the absorbing nature of HfC and appropriate coating thickness, the high solar absorptance of the coating can be partially attributed to the presence of HfO2 near the surface which acts similar to an antireflection layer. Assuming a two-layer model of the coating, an upper HfO2 layer and a HfC layer underneath it, reflectance spectra of the coated samples were simulated using SCOUT software and compared to the experimentally obtained spectra. For all the samples, best fit values of coating thicknesses were in the range 120–130 nm.

Modified surfaces using seamless graphene/carbon nanotubes based nanostructures for enhancing pool boiling heat transfer

Nanostructures are one of the promising options when it comes to the overall enhancement of boiling systems. Growing carbon nanotubes (CNT) over the Graphene (Gr) coated copper substrates is believed to be one such approach. This study attempts to deliver an insight into this aspect using Gr/CNTs heterostructures, over the copper substrate, using FC-72 as working fluid. PECVD technique was used to grow both the few layer Graphene (FLG) as well as CNT over the copper substrate. The as fabricated structures were characterised using SEM, TEM, Raman Spectroscopy, AFM and contact angle measurement. Through detailed experimentation, it was observed that the Gr/CNT heterostructures improve both the heat transfer coefficient (155%) and the critical heat flux (40%) of the surface as compared to bare copper surface. Most importantly, the boiling incipience superheat was found to reduce drastically (62%) as compared to bare copper surface, which is favourable for electronics cooling application. Increased nucleation sites, capillary effect, lateral heat transfer through Graphene intermediate layer and improved bubble dynamics caused these enhancements. The improved thermal transport properties of the surface as a result of Graphene based intermediate layer and the surface properties due to CNT produced a synergic effect to improve the boiling performance as a whole.

Optimization the electrophoretic deposition fabrication of graphene-based electrode to consider electro-optical applications

In this study, the optimized conditions of electrophoretic deposition (application potential, application time and concentration of stable graphene oxide (GO) suspension) for development of ultra-thin graphene film on copper substrate are introduced. The current density and deposition efficiency analysis, Ohm resistance measurement, SEM, FTIR and AFM techniques were done on prepared samples. The electrical conductivity of graphene coated copper substrate was increased three times more than bare copper. All of the carried tests showed that by increasing the key parameters of EPD, the average thickness of electrodeposited GO layers are increased continually so that the GO concentration effect is the most evident factor. The minimum sheet resistance and average thickness of electrodeposited RGO layers with uniform wrinkled morphology are achieved at EPD conditions of 2 V in 10 s and annealed at 200 °C for 1 min. The results of this research manifested that the EPD technique is a promising route to a low cost and well controllable method to fabricate a very conductive electrode base for electro-optical devices.

Controlling three‐dimensional ice template via two‐dimensional surface wetting

SignificanceDirectional freezing (DF) is a fast, scalable, and environmental friendly technique for fabricating monoliths with long‐range oriented pores, which can be applied toward a wide variety of materials. However, the pore size is typically larger than 20 μm and cannot be spatially controlled, which prevent the technique from being used more widely. In this work, effect of wettability of the freezing substrate on the pore size of monolithic polyethylene glycol cryogels is studied. Smaller pores can be generated via more hydrophilic substrates, and tubular pores smaller 5 μm can be created using a poly(vinyl alcohol) coated copper substrate. A numerical fitting between water contact angle of the substrates and pore size is then obtained. Moreover, pore size can be locally varied duplicating wetting patterns of the substrates. The concept of using two dimensional patterns to build monoliths with three dimensional microstructures can probably be extended to other material systems. DF is an effecient and scalable processing method for fabricating materials with long‐range oriented pores. However, the smallest pore feature size reported is around 20 µm, which is in many cases too large for application such as separation and catalysis. We show here, with exemplary cryogels, that both spatial control and feature size reduction (by one order of magnitude) can be realized in DF by controlling the wettability of the ice growth substrate. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4186–4192, 2016

Pool boiling heat transfer enhancement using vertically aligned carbon nanotube coatings on a copper substrate

In the present study, pool boiling heat transfer experiments are performed on a bare copper surface, a sandblasted copper surface, and carbon nanotube coated copper substrates. Experiments were conducted on the substrate surface area of 14 × 14 mm2 using de-mineralized water as the working fluid. The substrate is fixed tightly on the heater block, which is embedded with six cartridge heaters of total capacity 1500 W. Heat fluxes were measured using J-type thermocouples, which were aligned vertically along the heater block and also 1 mm from the top of the substrate. The pool boiling heat transfer experiments were conducted on bare, sandblasted and vertically aligned CNT coated copper substrates. The obtained results of sandblasted and CNT coated surfaces were compared with that of the bare copper surface. A remarkable enhancement of 38% in the CHF was observed on the CNT coated surface. The CNT coated surface was found to be effective in increasing the nucleate boiling and the CHF.

Spreading Behaviour and Joint Reliability of Sn–0.3Ag–0.7Cu Lead-Free Solder Alloy on Nickel Coated Copper Substrate as a Function of Reflow Time

Solder joint directly interfaces electrically, mechanically and thermally with numerous electronic components in electronic assemblies. Sn–Ag–Cu lead-free solder alloys for electronic assembly are being driven by the environmental issues concerning the toxicity of lead. In the present study, spreading behaviour, evolution of intermetallic compounds during solidification of Sn–0.3Ag–0.7Cu solder alloy on Ni coated Cu substrate and the related joint strength were studied as a function of reflow time. Experiments were carried out for various reflow times of 10, 100, 300 and 500 s at a reflow temperature of 270 °C. The solder alloy exhibited improvement in wettability on the substrate at longer reflow times. An increase in the IMC (CuNi)6Sn5 thickness was observed for samples reflowed up to 300 s and the thickness decreased for samples reflowed for 500 s. IMC layer formed were about 0.3, 1.15, 2.03, 1.94 μm during 10, 100, 300 and 500 s of reflow time respectively. The joint shear test was performed to assess the integrity of the Sn–0.3Ag–0.7Cu solder solidified on Cu substrates. The maximum joint strength was observed for samples reflowed for 100 s.

Thermal Performance of High Power LED on Boron Doped Aluminium Nitride Thin Film Coated Copper Substrates

Aims: The paper is aim to study the thermal performance of Boron doped Aluminium Nitride (B-AlN) thin film coated over Copper (Cu) substrate to improve surface configuration of the interface between two materials with different synthesis parameters. Study Design: Synthesis of Boron doped AlN thin film by sputtering and post processed for various temperatures. The processed samples were characterized to study the behavior of B doping as well as the annealing temperature in changing the properties of B doped AlN thin film. The structural and surface properties were studied and reported. Place and Duration of Study: Nano Optoelectronic Research Laboratory, School of Physics, University Sains Malaysia, Penang 11800, Malaysia, between December 2013 and July 2014. Methodology: B-AlN thin films were prepared with five different gas ratios over Cu substrates by DC-RF coupled sputtering method and suggested for thin film based thermal interface material Original Research Article Ong et al.; JSRR, 5(2): 109-119, 2015; Article no.JSRR.2015.078 110 (TIM). 3W green LED package was tested with B-AlN thin films coated Cu substrates through thermal transient and surface analysis. The results are compared with the performance of bare Cu substrates. Results: The thin film prepared with gas ratio of Ar 7: N2 13 coated at 200°C showed the lowest thermal resistance Rth (53.27 K/W), board to ambient thermal resistance RthB-A (36.03 K/W) and the lowest junction temperature Tj(120.98°C) at higher driving current (700 mA). Surface analysis results show that the thin film mentioned above exhibits low in surface roughness (8 nm) and range of valley depth (30-80 nm), which contribute in thermal performance of LED. Conclusion: Overall, B-AlN films coated with gas ratio of Ar 7: N2 13 are more favorable in reducing both total thermal resistance and junction temperature (Tj) of LED.