Achieving Good Bonding Strength of the Cu Layer on PET Films by Pretreatment of a Mixed Plasma of Carbon and Copper

Substrate-dependent deposition of Cu thin films by molecular dynamics simulations

Polyethylene terephthalate (PET)/Cu composite films simultaneously exhibit the merits of flexibility, light weight and excellent electrical conductivity, and thus have potential applications in 5G technology. Although PET/Cu films have been prepared by available experiments, few studies have further provided an atomic-scale understanding of these deposition processes. Here, the growth of Cu thin films on Cu and PET substrates has been carried out by molecular dynamics (MD) simulations and vacuum evaporation experiments. A detailed comparison of surface roughness, crystal structures and interfacial adhesion for Cu films deposited on these two substrates has been made. A conclusion has been achieved that Cu films deposited on the PET substrate exhibit lower surface roughness and stronger adhesion than those on the metal substrate. This investigation will provide a deep understanding of the substrate-dependent deposition performance of metal thin films.

From Metals to Polymers: Material Evolution and Functional Advancements in Current Collectors

The rapid advancement of rechargeable batteries is hindered by insufficient energy density, limited design flexibility, and safety concerns, which pose significant challenges to their practical application. This review summarizes the crucial yet often overlooked role of current collectors in addressing these challenges. Recent progress across four types of current collectors, deriving from metal foils, carbonaceous substrates, conductive polymers, and organic-inorganic hybrids is systematically analyzed. Metal foils, as the most widely used current collectors, now face challenges including corrosion susceptibility and high volumetric density. Carbonaceous and polymer-based alternatives offer lightweight design and structural flexibility, but face limitations in conductivity and scalable production. Notably, organic-inorganic hybrid current collectors, leveraging material engineering and hierarchical design, offer a promising avenue to enhance battery safety and intelligence. Further, potential directions for current collector development, emphasizing 1) enhanced battery performance, 2) multiscale structural adaptability, and 3) integrated multifunctional design, providing prospective insights for next-generation energy storage devices are outlined.

Manipulating the adhesion of electroless plated Cu film on liquid polymer crystal substrate for advanced microelectronic manufacturing

The evolution from subtractive to modified semi-additive (mSAP) and semi-additive (SAP) processes has heightened the importance of electroless plated (ELP) copper (Cu) peel strength in the printed circuit board industry. This study introduces a wet process for depositing Cu on liquid crystal polymer (LCP) using advanced electroless plating, incorporating a polyethylenimine (PEI) surfactant, a homemade nano-sized palladium (Pd) activator, and a micro-sculpturing treatment. By adjusting PEI immersion time and substrate roughness in the sub-micrometer domain, the peel strength of the ELP Cu film ranges from under 10 gf/cm to over 600 gf/cm. This wide range meets both low peel strength needs of mSAP peelable Cu foil and the high strength required in SAP. Characterization techniques, including atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), water contact angle (WCA) measurements, and fracture analysis, reveal that ELP Cu peel strength is driven by a synergistic effect between molecular interaction and physical anchoring.

Sputtered anti-reflection layer on transparent polyimide - substrate improves adhesion strength to - copper layer: effects of layer thickness and sputtering power

In order to shield the electronic circuits on a transparent polyimide (PI) substrate, an anti-reflection (AR) layer was deposited on a PI film via DC reactive magnetron sputtering. The effects of sputtering power and thickness of AR layer on the optical property and adhesion strength of the PI were investigated. The composition of the AR layer influences the bonding between layers. Sufficient thickness of the AR layer is essential to strengthen the adhesion between the PI and copper (Cu) layers. The sputtered AR layer on the PI also improves the barrier property for water vapor. The AR layer-sputtered PI substrates remain transparent and exhibit high peel strength to the Cu layer, suggesting their potential applications as reliable transparent substrates for modern electronic devices.