Influence of Surface Treatment of Polyimide Film on Adhesion Enhancement between Polyimide and Metal Films

Heo

ACS Appl. Mater. Interfaces

et al. 2020

The effects of micro-hole arrays in the thin metal films were studied as a method to release bending stress in flexible electrodes and flexible thin film transistors (TFTs). Interest in flexible electronics is increasing, and many approaches have been suggested to solve the issue of the electrical failure of electrodes or electrical components such as TFTs after repeated bending. Here, we demonstrate a micro-hole array structure as a common solution to release bending stress. Although micro-size cracks were generated and propagated from the hole edges, the cracks stopped within a certain range when enough stress was released. Moreover, since the crack sites were predictable and controllable, a fatal electrical breakdown in a conductive layer such as a metal electrode or the semiconducting junction of a TFT can be prevented by specifically arranging the hole arrays. Thin film layers fabricated without holes suffered an electrical breakdown due to random crack propagation during bending tests. Aluminum thin film electrodes prepared with arrays of 3 μm diameter holes and 25% hole area showed excellent durability after 300,000 bending cycles. The change in resistance was below 3%. The electrical characteristics of an a-IGZO TFT with the micro-hole structure were almost equivalent to a standard a-IGZO TFT. After 10,000 bending cycles, I ON and the ratio of I ON/I OFF remained >107 A and ∼107, respectively. Since the effective hole diameter is micrometer in size, fabrication does not require additional process steps or expensive process equipment. Therefore, the approach can be an important way to enhance the reliability of various electrical devices in flexible and wearable applications.

Section: Resultsmentioning

confidence: 99%

“…Therefore, all thin films were deposited in the high vacuum system to ignore these issues. 28,29 As shown in Figure 1, after several bending test cycles, many micro-cracks were randomly generated and propagated.…”

Section: Resultsmentioning

confidence: 99%

Stress Release Effect of Micro-hole Arrays for Flexible Electrodes and Thin Film Transistors

Heo

ACS Appl. Mater. Interfaces

et al. 2020

“…Most useful carbon materials have also been modified by several surface treatments, such as anodic oxidation [23], plasma [24,25], oxyfluorination [26], ozonization [27], or fluorination [28], Ar ion beam [29][30][31], several metal coatings [32][33][34], chemical treatments [35,36]. These treatments enable or enhance function and performance in real industrial applications, including adsorption [37], toxic removal [38,39], catalysis [40][41][42], adhesion or composites [43,44], electrochemistry [45][46][47], and so on.…”

Section: Introductionmentioning

confidence: 99%

An overview of new oxidation methods for polyacrylonitrile-based carbon fibers

Shin¹,

Park²,

Kim³

et al. 2015

Carbon letters

The process of oxidizing polyacrylonitrile (PAN)-based carbon fibers converts them into an infusible and non-flammable state prior to carbonization. This represents one of the most important stages in determining the mechanical properties of the final carbon fibers, but the most commonly used methods, such as thermal treatment (200°C to 300°C), tend to waste a great deal of process time, money, and energy. There is therefore a need to develop more advanced oxidation methods for PAN precursor fibers. In this review, we assess the viability of electron beam, gamma-ray, ultra-violet, and plasma treatments with a view to advancing these areas of research and their industrial application.

Period. Polytech. Elec. Eng. Comp. Sci.

“…All of these challenges have the immediate impact on the final parameters of printed structure. For the reason of very low thickness of printed structure (less than 1 μm), the surface roughness Ra of polymeric substrates are very important not just for achieving the good adhesion between the printed layer and substrate but also for the ink spreading on the substrate's surface [1,[7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Nano-ink Drops’ Behavior on the Polymeric Substrates’ Surfaces

Lukács

Pietriková

2016

The aim of this paper is analysis of the nano-ink behavior onto the polymeric substrates' surfaces. For this reason, three types of commonly used polymeric substrates for inkjet printing technology, polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and polyimide (PI) were analyzed. The impact of the surfaces' temperature on the ink spreading was mainly analyzed by using the microscopic methods. The higher temperature of substrate causes the fast evaporation process of the ink onto the substrates surface as well as causes the viscosity decreasing of the nano-ink. For this purpose, 2 silver based nano-inks were deposited by inkjet printer Jetlab 4xl-A with orifice diameter 70 μm. The main benefit of this paper lays in the optimizing of the spreading and coffee ring effect of several silver based nano-inks through the surface temperature changes and investigation of the deposited structures' shapes after the sintering.