Selective Electroless Copper Plating on Poly(ethylene terephthalate) Surfaces by Microcontact Printing

Selective electroless copper plating micro-coil assisted by 248 nm excimer laser

The polytetrafluoroethylene (PTFE), which was implanted with Ni ion to different energy and doses, fabricated metallic structures by selective electroless copper plating. The characteristic and microstructure of the copper film were studied using SEM and X-ray diffraction. Friction performance of the interface between copper film and basal body of PTFE was tested with a CETR UMT-2 (CETR Co., Campbell, CA, USA) multifunction micromechanics instrument. The test loads were 10, 20 and 40 N, while the line velocity was 8 mm s−1, and the frequency of data acquisition was 1 Hz. The Ni ion implantation replaces the complicated electroless plating surface pretreatment, and it is an assisted technique of electroless plating of copper on the surface of PTFE and plate Cu directly on its surface. Continuous, prepressing and uniformity plating was obtained with proper technique parameters and the dosage of Ni+. The frictional performance comprehensive property of copper film was remarkably influenced by different plating methods, annealing treatment and testing loads under unlubricated condition. The friction coefficients and wear rates changed with the varied load. Annealing treatment improves the tightness and uniformity of the copper film, while it decreases its cavity. Friction performance of copper film was thus increased. The mechanisms of friction and wear of copper film under different test conditions are also discussed.

A micro-contact printing (µCP) method has been applied to the fabrication of microstructures and electronics. We have successfully fabricated a copper wiring structure on flexible substrates using a combination of µCP, electroless plating, and electroplating. A nucleating agent ink pattern was printed by µCP onto polyethylene terephthalate, and polyethylene naphthalate. Nickel and copper thin films were electrolessly plated onto the pattern, and used as a conductive layer for subsequent copper electroplating. Copper wiring structures with a half-pitch of a 100 µm and a 250 µm line-and-space pattern, were successfully produced on flexible films at temperatures below 100 °C.

Microcontact printing of copper and polypyrrole on fluoropolymers

There is an increasing demand of methodologies to metallize complex polymer materials for application in electronics such as wearable devices and robotic products. In various metallization methods, electroless plating is a powerful and promising approach to meet this demand. The present conventional electroless plating requires pretreatment steps to deposit catalyst onto surfaces of polymer materials, which results in damages to their surfaces and also deformation of their shape because of the usage of strong acidic solvents. Furthermore, the adhesion strength between the polymer material and the metal layer is insufficient. To overcome these problems, a catalyzation step using supercritical carbon dioxide (sc-CO2) as the solvent is proposed.[1] The sc-CO2-assisted catalyzation enables a deep impregnation of catalysts into the polymer material without the pretreatment step, and this enhances the adhesive properties of the deposited metal on the polymer. By the sc-CO2-assisted catalyzation, electroless Ni-P plating of polyethylene terephthalate (PET) is realized. [1] Metallization of polymer materials with complex 3D structures is a more attractive topic, but it is widely accepted to be more difficult than film structures. Also, application the electroless plating via sc-CO2-asssited catalyzation to 3D-structured polymer materials remains unexplored. In this presentation, we report Ni-P plating of PET samples having complex 3D structures by the sc-CO2-assisited catalyzation process.A PET based material with a concavo-convex structure was designed and fabricated by the processing machine as shown in Figs. 1(a)–(b). Sc-CO2-assisted catalyzation process was performed in a high pressure reactor[1] containing palladium (II) hexafluoroacetylacetonate (Pd(C5HF6O2)2) as the palladium catalyst source at 70 °C under 15 MPa for 2 h. After the catalyzation process, the reactor was cooled to room temperature while maintaining the pressure in the reactor, and then the pressure in the reactor was reduced to atmospheric pressure. The collected PET sample from the reactor was kept under ambient atmosphere for two weeks, and then it was subjected to electroless Ni-P plating at 70 ℃ for 10 min.Fig. 1(c) shows the PET sample obtained after the sc-CO2-assisted catalyzation process followed by the post-treatment process. The volume of the catalyzed PET sample was scarcely changed. On the other hand, the post-treatment processes performed under the different conditions were found to cause undesired swelling and white turbidity of the PET sample, presumably because of microbubbles derived from residual CO2 in the PET. Fig. 1(d) shows an image of Ni-P successfully metallized on the PET surface. The electrical resistance of the Ni-P/PET material was 8.7 Ω, which is acceptable for electronic device applications. From these results, we concluded that sc-CO2-assisted catalyzation is applicable to metallization of PET materials with complex 3D structures. Reference [1] P.-W. Cheng, C.-Y. Chen, T. Ichibayashi, T.-F.M. Chang, M. Sone, S. Nishimura, J. Supercrit. Fluids 180 (2022) 105455. Figure 1

A facile process to fabricate metal coating on PET sheet: Preparation of highly active polymer brush/Ag particle and its application in electroless copper plating

Objects. Due to the polymer waste accumulation, the search for new directions for their utilization is urgent. Chemical recycling methods are of considerable interest, which allow one to obtain the original monomers or change the compositions of the copolymers. From the point of view of building a circular economy, a promising material is polyethylene terephthalate (PET), on the basis of which amorphous copolyesters can be obtained. The study aimed to analyze the simultaneous glycolysis and interchain exchange reactions of PET in the presence of the oligoethylene phthalate modifier with hydroxyl end groups and the study of isothermal crystallization of poly(ethylene phthalate-co-terephthalates) with different phthalate contents obtained in this way.Methods. Oligoethylene phthalate is synthesized by polycondensation. Poly(ethylene phthalateco-terephthalates) were obtained by the interaction of post-consumer PET with oligoethylene phthalate. The composition of the oligomer and copolymers was confirmed using Fourier-transform infrared spectroscopy, thermal characteristics and crystallization half-times were determined by differential scanning calorimetry.Results. In this work, the use of the post-consumer PET chemical recycling process, aimed at obtaining copolyesters under the influence of small modifier amounts was proposed. The process consisted in carrying out the combined interchain exchange and degradation with a complex oligoester different from PET. Poly(ethylene phthalate-co-terephthalate) copolymers were obtained via reaction of post-consumer poly(ethylene terephthalate) flakes and synthesized oligoethylene phthalate resin in the melt phase in the absence of catalyst. The effect of phthalate concentration in polymer on the isothermal crystallization of phthalate substituted poly(ethylene terephthalate) was estimated.Conclusions. The hypothesis about the possibility of using an oligoester modifier to obtain the PET-based copolymer at the high rate and without reducing the molecular weight to values characteristic of a monomer or oligomer has been confirmed. The process can be used to obtain random copolyesters based on post-consumer PET. The phthalate unit concentration increase is followed by decrease in the glass transition temperature, temperature and heat of fusion, and increase in crystallization half-times. Phthalate has a better ability to retard PET crystallization than 2-methyl-1,3-propanediol or furandicarboxylic acid, but is inferior to some of the other modifiers known.

Off-grade thermoplastic poly(ethylene terephthalate) of industrial manufacturers was partially depolymerized to synthesize poly(ethylene terephthalate) oligomers. Influences of reaction time, ethylene glycol/poly(ethylene terephthalate) molar ratio, catalyst concentrations and particle size of off-grade poly(ethylene terephthalate) on yield of partial glycolysis reaction were investigated based on Box–Behnken's design of experiment. Thermal analyses of glycolyzed products was carried out using differential scanning calorimetry. The optimum samples were also well characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy and carbon-13 nuclear magnetic resonance spectroscopy. The optimal conditions to synthesize poly(ethylene terephthalate) oligomer for a 120-min glycolysis reaction time were: using ethylene glycol/poly(ethylene terephthalate) of molar ratio of 2 with no catalyst and using granule-shaped poly(ethylene terephthalate). Then, endcapped poly(ethylene terephthalate) oligomer as a compatiblizer for preparing poly(ethylene terephthalate) nanocomposites was produced via reaction between maleic anhydride/phthalic anhydride composition and optimized poly(ethylene terephthalate) oligomers based on central composite design of experiment. The combination of reaction time of 106 min and phthalic anhydride/maleic anhydride molar ratio of 0.85 gave the best results based on d-spacing and peak intensity of nanocomposite samples. Hence, melt mixing of endcapped poly(ethylene terephthalate) with organoclay produced a good intercalation of layered silicate and good dispersion of clay in endcapped poly(ethylene terephthalate) matrix. Analysis of variance was studied for both glycolyzed products and functionalized poly(ethylene terephthalate) oligomers.

This work demonstrates a simple printed electronics process to obtain the copper pattern by flexography. The nano-copper suspension was synthesized by liquid chemical reduction method. The conductive ink was prepared with nano-copper and glycerol. The copper pattern was printed by a flexo graphic printability tester and then dried in an oven at 80 ℃. The copper in square pattern exhibits better conductivity than that in hexagon, because of the higher surface line density. The confocal laser scanning microscope (CLSM) indicates that the heights of the copper patterns are different in relation to printing direction and shape. The morphologies of the two kinds of the copper pattern were fine. This process could apply to the poly (ethylene terephthalate) (PET) substrate and is easily operated. The printed copper pattern would be used for transparent electrode, printed circuit board, antenna and flexible displays.

Globally, an estimated 7.4 billion tons of plastic have accumulated, with projections suggesting this could escalate to 40 billion metric tons by 2050. Unfortunately, only about 10% of this plastic is recycled, due to the lack of sustainable and economical solutions [1]. Alarmingly, over 70% of plastic waste ends up in landfills or oceans where it gradually decomposes into small particles (average diameter less than 5 mm), often referred to as microplastics (MPs). This widespread presence of microplastics poses a significant hazard to global ecosystems and human health. Microplastics can be ingested by organisms through various pathways including consumption of contaminated food, inhalation of polluted air, and dermal contact [2].Polyethylene terephthalate (PET), is the second most abundant plastic produced worldwide due to its extensive use in consumer packaging. Conventional mechanical recycling of PET often leads to the loss of its desirable properties [3]. Therefore, there is significant interest in chemical recycling technologies capable of depolymerizing PET. Through chemical hydrolysis at high temperatures, PET can be broken down into its constituent monomers, terephthalic acid and ethylene glycol. Nonetheless, the subsequent chemical separation of these products, particularly ethylene glycol (EG), presents challenges due to its high boiling point, viscosity, and water solubility, necessitating energy-intensive distillation processes. In response to this challenge, electrochemical methods have gained popularity for oxidizing PET hydrolysates into valuable products such as formic acid and glycolate, thereby offering a more sustainable pathway for upcycling [4]. However, most studies on electrochemical upcycling of PET still utilize a two-stage process. Initially, PET is hydrolyzed in a potassium hydroxide KOH solution at temperatures exceeding 80°C. Subsequently hydrolysate is used as an electrolyte to produce formate at the anode while hydrogen is produced at the cathode.Botte's group is investigating electrochemical approaches to convert plastics into valuable chemicals [5]. An effective enhanced electrocatalytic hydrolysis process for recycling PET waste into value-added chemicals was developed. This novel approach integrates the hydrolysis of PET with the concurrent electrochemical oxidation of ethylene glycol employing transition metals as catalyst and using mid temperature conditions. The effect of different variables on the overall conversion and the product distribution were evaluated. Operating time, voltage and particle size were varied, and the end products were characterized by FTIR, SEM, NMR, and IC. Our studies indicate that the electrochemical approach enhanced PET hydrolysis in comparison to traditional chemical hydrolysis [6] along with the oxidation of ethylene glycol into formic acid/formate in a single process eliminating the need for separate hydrolysis. Optimization of this process could be a sustainable approach for upcycling of PET microplastic into valuable products.[1] Li, M. and S. Zhang, Tandem Chemical Depolymerization and Photoreforming of Waste PET Plastic to High-Value-Added Chemicals. ACS Catal. 2024. 14(5): p. 2949-2958,doi: 10.1021/acscatal.3c05535.[2] E. Bäckström, K. Odelius, and M. Hakkarainen, “Trash to Treasure: Microwave-Assisted Conversion of Polyethylene to Functional Chemicals,” Ind. Eng. Chem. Res., vol. 56, no. 50, pp. 14814–14821, Dec. 2017, doi: 10.1021/acs.iecr.7b04091.[3] R. K. Brizendine et al., “Particle Size Reduction of Poly(ethylene terephthalate) Increases the Rate of Enzymatic Depolymerization But Does Not Increase the Overall Conversion Extent,” ACS Sustain. Chem. Eng., vol. 10, no. 28, pp. 9131–9140, Jul. 2022, doi: 10.1021/acssuschemeng.2c01961.[4] Y. Li, L. Q. Lee, H. Zhao, Y. Zhao, P. Gao, and H. Li, “Alcohol–alkali hydrolysis for high-throughput PET waste electroreforming-assisted green hydrogen generation,” J. Mater. Chem. A, vol. 12, no. 4, pp. 2121–2128, Jan. 2024, doi: 10.1039/D3TA05522A.[5] G. G. Botte, “Processes for electrochemical up-cycling of plastics and systems thereof,” WO2021257972A1, Dec. 23, 2021 Accessed: Jul. 21, 2023. [Online]. Available: https://patents.google.com/patent/WO2021257972A1/en[6] F. Lu and G. G. Botte, “Understanding the Electrochemically Induced Conversion of Urea to Ammonia Using Nickel Based Catalysts,” Electrochimica Acta, vol. 246, pp. 564–571, Aug. 2017, doi: 10.1016/j.electacta.2017.06.055.

Electroless nickel plating has been extensively applied on copper circuits as an under-layer deposition for solder joints, since it is possible to deposit on the isolated patterns without an outer electrode. A palladium catalyst is generally used for the electroless nickel plating reaction on the copper patterns, because copper has a lack of catalytic activity for initiation of the deposition reaction. The electroless nickel plating is applied on the condensed copper patterns by using the palladium catalyst ; however, nickel deposits tend to occur on the resin surface due to the adsorption of palladium ions on it.Dimethylamine-borane (DMAB) has a feature of catalytic activation power on the copper. Therefore we applied dilute nickel plating solution containing DMAB as an initiator for electroless nickel deposition on the copper surface instead of applying the palladium catalyst. Selective nickel plating on the copper patterns without deposition on the resin substrate was achieved using a dilute nickel plating bath containing DMAB. In addition, the strength of solder joints was improved by introducing this process. In this way, nodules on the nickel surface were greatly suppressed, and strong joints between the solder and deposited nickel were achieved.

Summary form only given. This article reports a study of the behavior of bacterial adhesion to polyethylene terephthalate (PET) which was modified by acetylene (C/sub 2/H/sub 2/) plasma immersion ion implantation (PIII). These surface-modified PETs were characterized by means of X-ray photoelectron spectroscopy (XPS) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FT IR). The capacities of Staphylococcus aureus (SA), Staphylococcus epidermidis (SE), Escherichia coli (EQ), Pseudomonas aeruginosa (PA) and Candida albicans (CA) for adhesion to PETs were quantitatively determined by the plate counting and Gamma-ray counting of /sup 125/I radio labeled bacteria in vitro. The results indicated that the capacities of five types of bacteria for adhesion to PETs were all suppressed by PHI treatment. The adhesion of SA on the surface of C/sub 2/H/sub 2/ PIII modified surface was reduced to 1/10 of that on the untreated PET surface. The capacities of SE on the modified surface were 25% comparing with that of the untreated surface. XPS and ATR-FTIR spectra showed amorphous carbon structure appeared after C/sub 2/H/sub 2/ plasma immersion ion implantation. This suggests that the improvement of bacterial adhesion to PET might come from the formation of an amorphous carbon phase by PHI. It is believed that the composition change of the modified surface layer would cause the improvement of the bacterial adhesion.

This study explores the impact of blending polyethylene terephthalate (PET) with polybutylene terephthalate (PBT) on the thermal, structural, and mechanical properties of 3D-printed materials. Comprehensive analyses, including Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and mechanical testing, were conducted to assess the influence of blend composition. FT-IR confirmed that PET and PBT blend physically without transesterification, while TGA showed enhanced thermal stability with increasing PET content. XRD revealed that PET and PBT crystallize separately, with the crystallinity decreasing sharply for blends with more than 50% PET. The DSC results indicated that PET effectively slows down the crystallization kinetics of PBT, promoting cold crystallization. Mechanical tests demonstrated that the elastic modulus remains relatively unchanged, but the strain at break decreases with a higher PET content, indicating increased stiffness and reduced ductility. Overall, incorporating PET into PBT improves 3D-printability and dimensional stability, reducing warpage and enhancing print precision, making these blends advantageous for 3D-printing applications.

We report a simple, low-cost method for the fabrication of copper wires and contacts on a wide range of flexible, rigid, and inert polymeric substrates. This method relies on procedures to oxidize the polymeric substrates to form surface-bound carboxylic acid groups. Patterning of an aluminum porphyrin ink using microcontact printing results in the formation of an aluminum porphyrin monolayer that is covalently anchored to the oxidized polymer surface via an aluminum-carboxylate bond. We characterize this monolayer using ultraviolet-visible absorption spectra, reflection-absorption infrared spectroscopy, and contact angle measurements. Patterned aluminum porphyrin monolayers bind a Pd/Sn colloidal catalyst from solution that subsequently initiates the selective deposition of copper in an electroless plating solution. We demonstrate the fabrication of patterned copper films on a variety of both flexible and rigid polymers with minimum feature sizes of 2 microm over 2 cm(2) substrates. Measurements of electrical resistivity of copper wires fabricated on flexible poly(ethylene naphthalate) (PEN) substrates as a function of the bending radius show no negative impact on electrical performance at bending radii as small as 500 microm. Permanently damaging the PEN substrate by creasing (corresponding to a bending radius of 100 microm) results in only a modest increase in resistivity.

Recycled poly(ethylene terephthalate) (R‐PET) was blended with four types of polyethylene (PE), linear low density polyethylene (LLDPE; LL0209AA, Fs150), low density polyethylene (LDPE; F101‐1), and metallocene‐LLDPE (m‐LLDPE; Fv203) by co‐rotating twin‐screw extruder. Maleic anhydride‐grafted poly(styrene‐ethylene/butyldiene‐styrene) (SEBS‐g‐MA) was added as compatibilizer. R‐PET/PE/SEBS‐g‐MA blends were examined by scanning electron microscopy (SEM), differential scanning calorimeter (DSC), dynamic mechanical analysis (DMA), and mechanical property testing. The results indicated that the morphology and properties of the blends depended to a great extent on the miscibility between the olefin segments of SEBS‐g‐MA and PE. Due to the proper interaction between SEBS‐g‐MA and LDPE (F101‐1), most SEBS‐g‐MA, located at the interface between two phases of PET and LDPE to increase the interfacial adhesion, lead to better mechanical properties of R‐PET/LDPE (F101‐1) blend. However, both the poor miscibility of SEBS‐g‐MA with LLDPE (LL0209AA) and the excessive miscibility of SEBS‐g‐MA with LLDPE (Fs150) and m‐LLDPE (Fv203) reduced the compatibilization effect of SEBS‐g‐MA. DSC results showed that the interaction between SEBS‐g‐MA and PE obviously affected the crystallization of PET and PE. DMA results indicated that PE had more influence on the movement of SEBS‐g‐MA than PE did. Copyright © 2010 John Wiley & Sons, Ltd.