The makers of high-end cell phones, game systems, MP3 players and other handheld devices are promoting a new innovation: scratch-resistant screens. For example, when Mobiado launched its new Luminoso handset in January, the marketing campaign emphasized that “The front screen is coated with Diamondshield®, the most advanced coating available for polymer substrates.”
Diamondshield Scratch-Resistant Coatings
Diamondshield is a water-clear coating developed by the Diamonex Products division of Morgan Advanced Materials (MAC) that gives polycarbonate and acrylic screens – and other plastic components such as keypads and casings – a previously unattainable scratch-resistance, comparable to glass, while maintaining the weight savings, impact resistance, formability and other benefits of plastic.
Is such scratch-resistance just another feature used to justify premium pricing but offering little real value? Or does it satisfy real user needs, making it destined to become an ubiquitous feature of all handheld devices in the future?
Dream Feature or the Nightmare of Feature Creep?
Of course, the market for cell phones and other handheld devices is constantly evolving, and manufacturers are always under competitive pressure to differentiate their products, with appealing designs, smaller size, lighter weight, extended battery life, and yes, lots of new features. This trend, known as feature creep, can be counterproductive with some segments of the consumer market, when products are perceived as complex and difficult to use. Professor Roland Rust of the University of Maryland recently wrote in the Harvard Business Review that “feature fatigue” can be detrimental to a cell phone manufacturer’s brand image and inhibit future sales.
Scratch-Resistance Adds Value
The question for manufacturers is: when does a new feature add value for the consumer without having the detrimental effect of increasing complexity and thereby decreasing usability?
Fortunately, scratch-resistant screens are one of the relatively rare feature enhancements that add value to a device without making it more complicated to use. In fact, a scratch-resistant screen actually makes a device more useable, by protecting the viewability of the display.
Scratch-Resistance Improves Usability
Scratch-resistant screens also enhance usability by allowing people to carry the device in a pocket without worrying about the risk of scratching the screen and other components. After all, how usable is a pocket-sized device if you cannot carry it in your pants, your purse or your backpack?
Value of Scratch-Resistant Screens
No longer are cell phones used solely for making telephone calls. Cell phone subscribers want to be able to take advantage of graphical user interfaces (GUI) and graphical applications. Mobile network operators know that graphically-based applications such as short message service, photo sharing and video, are the key to increasing the average revenue per user.
Protecting High Resolution Screens
The quality of the display is also critical to handheld gaming devices, digital music players and personal digital assistants. Consumers pay a premium for well-designed GUIs and larger displays, with higher resolution, all of which depend on a clear, scratch-free screen.
Case Study Highlights the Need for Scratch Resistant Screens
The consumer demand for scratch-resistance screens on handheld devices became especially evident 18 months ago, when Apple released the iPod Nano, and users discovered that the beautifully-designed devices could not stand up to minimal wear and tear. A class-action lawsuit ensued, and some analysts blamed the scratchable Nano for a short-term drop in the Apple Inc. stock price.
Hardness of Diamondshield Scratch-Resistant Coatings
Silicone or acrylic hard-coating, applied by conventional methods such as dip coating, spray coating, spin coating, or flow coating, does provide some protection compared to uncoated polycarbonate. However, it is not nearly as effective as Diamondshield, which is applied via chemical vapor deposition (CVD) and takes on the hardness and smoothness characteristics of natural diamonds, and the typical thickness is around 3-5 μm.
As measured by micro indentation, Diamondshield exhibits hardness of 2-4 GPa, offering four to eight times more scratch resistance than typical silicone or acrylic hardcoatings, which exhibits hardness of 0.2 – 0.5 GPa. The hardness of Diamondshield is comparable to glass (4-5 GPa).
Diamondshield Provides a Low Friction Coating
Another factor contributing to scratch-resistance is low friction, which allows objects to slide across the surface without galling. Diamondshield has a friction coefficient of 0.3. The friction coefficient for glass is 0.6, and for silicone or acrylic hardcoats, 0.7.
Diamondshield Provides a Hydrophopbic Coating
Diamondshield also provides good hydrophobicity, a useful attribute which helps prevent the collection of oils from the users hands and face on the device surface, even when users rest the cell phone screen against their check.
Optical Properties of Diamondshield Coatings
Diamondshield has exceptional transparency with a very low index of refraction and virtually no noticeable light absorption in the visible wavelength region, even on multi-dimensional parts. Therefore, Diamondshield requires no compromise of optical performance or cosmetic appearance.
An Insurance Policy against Wear and Abrasion
For these reasons, Diamondshield’s scratch-resistance is well-suited for handheld devices, providing high value to users. The diamond-like coating essentially provides consumers with insurance, extending a product’s useful life by protecting critical components, such as screens and keypads, from inevitable wear and abrasion. Diamondshield also protects the device’s cosmetic appearance, a valued benefit for consumers and an increasingly-important measure for manufactures to preserve brand image.
Diamondshield is not only useful in protecting the exposed screens and keypads of “candy bar-style” cell phones and MP3 players, but it also serves an important function with flip phones and clamshell-style devices. The folding design serves to protect the screen and keypad from impact and abrasion by other objects, but the keyboard and screen of a clamshell device can be damaged if they repeatedly come in contact with each other. This problem is mitigated by pads and spacers to maintain separation between the two sides of the device. However, this solution adds undesirable bulk to the design of the entire device. By coating the screen and the keypad with Diamondshield, manufacturers can eliminate the spacing between the two sides of the clamshell to achieve the smallest possible form factor.
Scratch-resistance with Diamondshield appears to be a logical next step in the evolution of cell phones and other handheld devices. Displays are continually improving, with better resolution and brighter colors, and the growing use of graphically-based applications such as gaming, digital photography, and video entertainment, places more emphasis on the quality of the visual experience.
The market penetration of scratch-resistant coatings is positioned to grow quickly during the next few years, from an innovative feature of high-end devices to a ubiquitous feature that consumers will expect in every device. Fortunately, the Diamonex Products division of Morgan Advanced Materials has developed the Diamondshield coating, a proven solution that satisfies the market demand and that manufacturers can easily incorporate into their product line.