Characterization of flexible copper laminates fabricated by Cu electro-plating process

Flexible copper clad laminates(FCCLs) were fabricated using the electro-plating process and the combined effect of the current density and plating time on their surface morphology,texture,hardness,electrical resistivity and folding behavior was evaluated.To achieve Cu layers with similar thicknesses,the current density was varied in the range of 0.2-3 A/dm2 and the plating time was controlled in the range of 0.5-7.5 h to compensate for the variation of the current density.The surface morphology,hardness,and folding behavior were characterized by atomic force microscopy,nanoindentation technique and Massachusett Institute of Technology folding endurance test,respectively.The X-ray diffraction patterns indicated that the Cu phase was formed without any secondary phases;however,the preferred orientation changed from(220) to(111) as the current density increased over 1 A/dm2.In addition,it was observed that the root-mean-square and hardness values decreased when the current density increased and the plating time decreased simultaneously.The electrical resistivity was as low as approximately 21 nΩ·m and the number of cycles without failure in the folding test was over 15 000,which were comparable to those of commercial FCCLs.

Fabrication of two-layer flexible copper clad laminate by electroless-Cu plating on surface modified polyimide

A flexible copper clad laminate(FCCL) was fabricated using electroless-and electro-Cu plating processes and the effects of pre-treatment time on the adhesion strength of the FCCL were evaluated based on interfacial morphology.The neutralization and catalyst time were varied in the range of 0-20 min and 0.1-10 min,respectively,and the interfacial condition of the FCCL was characterized by atomic force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS).It is observed that the peel strength increases significantly as the neutralization and catalyst time increase.Peel strength as high as 7.2-7.3 N/cm is obtained as the neutralization and catalyst time increase up to 20 min and 10 min,respectively,which is comparable to the strength achieved by the conventional laminating and sputtering processes.These improvements are probably due to an increase in the surface roughness of polyimide(PI),the activated surface condition,and the adsorption of palladium ions/atoms(Pd) on the PI surface which act as nucleation sites for Cu.

Roles of humidity and heat treatment temperatures on YBa_2Cu_3O_(7-x) coated conductors by trifluoroacetic acid-metal organic deposition process

YBa2Cu3O7-x(YBCO) films were fabricated on an LAO substrate using the trifluoroacetic acid-metal organic deposition(TFA-MOD) method and the effects of the humidity and heat treatment temperatures on the microstructure,degree of texture and critical properties of the films were evaluated.In order to understand the combined effects of the humidity and the calcining and firing temperatures on critical properties,heat-treatment was performed at various temperatures with the other processing variables fixed.The films were calcined at 400-430 ℃ and fired at 750-800 ℃ in a 0-12.1% humidified Ar-O2 atmosphere.The texture was determined by pole-figure analysis.The amount of the BaF2 phase was effectively reduced and a sharp and strong biaxial texture was formed under a humidified atmosphere,which led to increased critical properties.In addition,the microstructure varied significantly with firing temperature but changed little with calcining temperature.The highest IC of 40 A/cm-width,which corresponds to JC value of 1.8 MA/cm2,was obtained for the films fired at 775 ℃(in 12.1% humidity) after calcining at 400-430 ℃.It is likely that the highest IC value is due to the formation of a more pure YBCO phase,c-axis grains,and a denser microstructure.

Development of a two-stage virtual impactor for the generation of micrometer-scale monodisperse aerosols

Monodisperse particles are useful across a wide range of industrial applications,such as LCD displays,solar cells and rechargeable batteries,due to their uniformly small sizes.However,generating high volumes of monodisperse particles remains challenging.In this study,it was aimed to generate mono-disperse aerosols by classifying micrometer-scale solid aerosol particles within a narrow size range.Accordingly,a new particle-size classification device with two virtual impactors connected in series and clean air cores was developed.The first-stage virtual impactor had a slightly larger cutoff size than the second-stage,and the major flow discharged from the first-stage was directed to the second-stage.The target particle size range was altered by changing the nozzle sizes in the first and second stages or by adjusting the flow rate.Subsequently,the classification performance of the two-stage virtual impactor was simulated and validated through an experiment using Arizona test dust.The implemented combi-nations of cutoff sizes for the first and second stages were 3.0 and 2.0μm,3.9 and 2.7μm,or 6.7 and 4.8μm.As a result,monodisperse aerosol particles were classified at a geometric standard deviation of 1.04-1.14 and a particle size range of 2-6.7μm.The two-stage virtual impactor developed herein may be useful for various research and performance evaluations,as it can classify micrometer-scale solid particle aerosols that exhibit high monodispersity.