Peeled Film Research Articles

Cassette-like peeling system for testing the adhesion of soft-to-rigid assemblies

A novel cassette-like peeling system is developed to address the limitations of current peeling standards when evaluating bonding quality of soft-to-rigid assemblies. The system transforms the translation of a specimen in the conventional peeling configuration to rotation via a cassette-like spool clamping the specimen. The peeled film is loaded by tension to drive the winding of the spool, thus achieving self-similar crack propagation and a stationary peeling front unrelated to the stiffness of the film. These features enable the system’s compatibility with most universal testers and in situ observation of crack tip morphology with optical instruments. Analysis to derive the intrinsic fracture energy when peeling a soft film is conducted based on Griffith energy balance, making use of which, a parametric study is performed to clarify the related mechanisms. We carry out a comprehensive validation of the cassette-like peeling system by performing a series of peeling tests using our in-house prototype and by comparing the results with those from the conventional system. Owing to its universality and ease-of-use, the proposed cassette-like peeling system can potentially be applied to the development of the next generation of peel test standards.

Honeycomb porous films of pentablock copolymer on liquid substrates via breath figure method and their hydrophobic properties with static and dynamic behaviour

The peeled film obtained on the isopropanol substrate through breath figure method exhibits the best hydrophobic properties, and the water droplet impact behavior shows an obvious rebound tendency and a weak maximum spreading diameter.

Self-scrolling ability of differentially acetylated chitosan film

Chitosan film cast on a glass slide was exposed to acetic anhydride vapor, resulting in an acetylation gradient in the film, with preferential acetylation of the exposed surface. The difference in degree of acetylation between the two surfaces of the peeled film was confirmed by attenuated total reflection infrared spectroscopy. Upon immersion of the film in water, differential swelling occurred because the more highly acetylated surface absorbed less water, and the resulting bending moment caused self-scrolling with the more highly acetylated surface inside. Simultaneous peeling and scrolling of films with a thickness of micrometer order, using dilute aqueous hydrofluoric acid, afforded tightly rolled chitosan microtubes. This simple self-scrolling mechanism is potentially applicable for micro-scale design with various naturally occurring polymers.

PS50 切削原理を利用した界面強度評価(フェロー賞対象ポスターセッション)

The purpose of this paper is to develop the evaluation method of interfacial strengths with a micro cutting system. The interfacial strength of thin films is crucial for the reliability assessment of electronics packages and MEMS devices. There have been a lot of experimental and theoretical studies about the measurement of interfacial strengths. However, it is still under developing stages, because it is quite difficult to measure it quantitatively for micro- and nano-thickness films. Recently, SAICAS(Surface and Interfacial Cutting Analysis System) has been developed and used for the evaluation of the mechanical properties in micro- and nano-thickness films. In this paper, we carried out the numerical simulation of SAICAS micro cutting tests by Multibody dynamics with HyperWorks and analyzed the behavior of peeled film.

Determination of silicon and copper in aluminium alloy for semiconductor devices using ICP-OES after sodium hydroxide-nitric acid decomposition

We have established a method for assaying the quantities of silicon and copper in aluminium alloys deposited by sputtering on silicon substrates. This method involves the following procedure: 1) The alloy film is peeled away with a metal blade, while taking care not to damage the silicon substrate. 2) The peeled film is dissolved in a hot 1% aqueous solution of sodium hydroxide. 3) The solution is acidified with nitric acid, and the quantities of silicon and copper are assayed by inductively coupled plasma optical emission spectrometry(ICP-OES). We have clarified that this method can assay silicon and copper in as little as 20 mg of peeled aluminium alloy.

Effects of electroplated Cu thickness and polyimide plasma treatment conditions on the interfacial fracture mechanics parameters in the Cu/Cr/polyimide system

The interfacial fracture energies of Cu/Cr/polyimide systems are deduced by subtracting work expenditure from the peel strength. Two methods were used to obtain the work expenditure: on based on the X-ray measurement of the plastic strain of peeled metal film and the other based on a theoretical analysis of the foundation model for the attached part of the metal film. These two methods yield reasonably consistent work expenditure in most cases, imparting validity to the experimental and theoretical methods used here. The interfacial fracture energies of the Cr/polyimide interface were shown w.r.t., the film thickness and rf plasma power density activating the polyimide surface. The phase angle of the interface crack between the Cu and polyimide is determined by using elasto-plastic finite element analysis and the path independence of theJ-integral. The presence of the polyimide interlayer increased mode mixity, and the phase angles were virtually independent of the metal film thickness, which is consistent with the nearly constant interfacial fracture energy with Cu film thickness.

Structural and tribological characteristics of diamond-like carbon films deposited by pulsed laser ablation

Diamond-like carbon (DLC) films were deposited by pulsed laser ablation (PLA) on Si (100) and Ti–6Al–4V alloy substrates at four different temperatures. The bonding characteristics of the films were studied by X-ray photoelectron (XPS) and Raman spectroscopy techniques. The ratio of tetrahedral to trigonally coordinated carbon atoms was estimated by XPS successfully. The fraction of tetrahedrally bonded atoms in the films deposited on Si at room temperature was estimated to be ∼63 at.% which decreased to ∼33 at.% as the substrate temperature increased to 400°C. The Raman spectroscopy results of these specimens agree qualitatively with these observations. Also, using Raman spectroscopy, the residual compressive stress was also estimated in fully adherent films on Si substrate to be ∼3 GPa with reference to the value of stress present in a free-standing peeled off film from the Ti-alloy substrate. This value is consistent with the residual stresses estimated in the earlier results. The abrasive wear rates have been correlated during the initial stages of the well adhered films with the sp 3/sp 2 ratios. The importance of suitable dopants and the interfacial interlayers in reducing internal compressive stresses in these films is discussed.

Adhesion and delamination of tantalum and chromium films on glass

The adhesion and delamination behavior of sputtered Ta and Cr films on barium boroaluminosilicate glass were investigated. The locus of delamination was determined by XPS analysis of peeled film strips to be at the film-glass interface. We found a strong correlation between the intensity and thickness of the metal suboxide interphase layer formed and resistance to film delamination. For Ta, we found that the presence of a sufficiently thick TaOx layer at the glass-film interface effectively prevented debonding of the film from the glass substrate. The role of oxygen in metal-glass bonding chemistry was explored by sputter deposition of metal films with in situ oxygen or air dosing. SIMS sputter-depth composition profiles confirmed the presence of a Ta-oxide phase (20-90 nm, depending on the dosing conditions) at the film-glass interface. We found that the delamination mechanism was prevented by in situ oxygen doping of the glass surface during film deposition. The cleanliness of the glass surface prior to sputtering, the ability to provide surface oxygen, and the film deposition conditions were found to be critical in avoiding delamination of the films from the glass. Although other factors may be involved in the mechanism of adhesion of Ta, the ability of the glass surface to provide oxygen for bonding is the overriding one, as shown in this work. Thus, oxide formation and chemical bonding at the metal-glass interface are more important than surface topography in the bonding of oxygen-active transition metals, such as Ta and Cr, to glass.

Influence of annealing ambients on ZrSi2 formation

The formation of zirconium silicide was studied in many kinds of annealing ambients, i.e., Ar-H2, Ar-O2, N2-O2, Ar-N2-O2, and Ar-air. When the ambient involves both N2 and O2, such as Ar-N2-O2 and N2-O2, in the range of [N2]/([N2] +[O2])>0.9, the film resistivity becomes higher than that of the Ar-O2 case, even at the same O2 concentration. This is because a thick ZrOxNy layer is formed on the ZrSi2 layer. When the ratio of [N2]/([N2] + [O2]) in the Ar-N2-O2 ambient is less than 0.9, the films are partially peeled off from the substrate. The resistivity of a film annealed in the Ar-air ambient is very high at even a few ppm O2. This is because the film peels off and then the oxidation of the peeled film is accelerated by a small amount of H2O in air.

Formation of GaAs thin films for photovoltaic applications by peeled film technology

Formation of GaAs thin films for photovoltaic applications by peeled film technology

High efficiency GaAs thin film solar cells by peeled film technology

p-GaAs/n-GaAs thin film concentrator solar cells were fabricated by Peeled Film Technology. This is the first paper that reports the concentration characteristics of thin film solar cells. The energy conversion efficiency of thin film solar cells at a concentration ratio of 109 is 9.4% and the output power density is 0.82 W/cm 2 · n-Ga 1− x Al xAs/p-GaAs heterojunction thin film solar cells were also fabricated. The initial heterojunction thin film solar cell with a Al mole fraction of 0.5 showed an efficiency of up to 13.5% (AM 1.5). It is proposed that Multi-Peeled Film Technology will give numerous GaAs thin films by selective etching of (GaAl)As/GaAs multi-layered structures.