Thinning and Coating Process of Mobile Phone Cover Glass

According to the needs of various terminal applications, glass cover panels require various optical glass processing processes such as cutting, edging, drilling, polishing, thinning, chemical strengthening, printing, laser engraving and coating. Today we will introduce the thinning and coating of mobile phone cover glass, which are the most important parts of the whole manufacturing process.

Cover glass thinning process

The glass mentioned in this article is not the 3mm, 5mm, 8mm or even 10mm glass for civil use, but the cover glass for electronic products such as smartphones and tablet computers. Among the glasses currently on the market, the thinnest is 0.15 mm. There is a special thinning process that reduces the thickness of the glass.

Since Steve Jobs started using Corning Gorilla Glass for his iPhones, there emerges a new component for electronic products—cover glass. At the same time, the pursuit of thinner and lighter in the industry is also urging glass manufacturers to make changes to make thinner cover glass.

iPhone cover glass
iPhone cover glass

Currently, the thinnest glass of gorilla can be made 0.4mm, and the Asahi Glass can make 0.2mm glass. In general, people’s expectations for cover glass are nothing more than two:

1. Reduce the space occupied by the glass.

2. Make the glass cover a certain flexibility.

Mobile phone cover glass thinning process

There are not many processes for glass cover thinning: pre-cleaning—etching and thinning—–secondary cleaning——-grinding (single or double sided)—–post-cleaning—–check the package

Pre-cleaning: Remove the stain on the surface of the glass cover. It is one of the key steps affecting the effect of thinning.

Etching and thinning:  using acid and alkali to etch the glass cover achieve the purpose of thinning. The conditions and parameters (time, potash ratio, temperature, etc.) vary from manufacturer to manufacturer, which is the technical secret of the manufacturer.

Secondary cleaning: Clean the residue of the glass cover.

Grinding: To obtain a bright, flat surface. It is one of the key processes for appearance assurance and thickness tolerance control.

Post-cleaning: Clean the remaining grinding powder.

Check the packaging: The standard for the appearance of the glass is different depending on the requirements of the customer.

Mobile phone cover glass thinning treatment

1, multiple pieces of upright soak

2, waterfall flow processing

3, single piece vertical spray

Cover glass coating process

At present, vacuum magnetron sputtering coating technology is a widely used thin film deposition technology. The continuous development of sputtering technology and the exploration of new functional films have enabled the application of magnetron sputtering coating technology to be extended to many productions and scientific research fields.

magnetron sputtering system
magnetron-sputtering-system

magnetron sputtering coating applications

In the field of microelectronics, as a non-thermal coating technology, magnetron sputtering coating technology is mainly applied to materials that are not suitable for chemical vapor deposition or metal organic chemical vapor deposition. Moreover, using magnetron sputtering can obtain a large-area uniform film.

Magnetron sputtering technology is also used in optical films such as antireflection glass, low emissivity glass and transparent conductive glass. In the production of transparent conductive glass, the ITO conductive glass prepared by sputtering has an average transmittance of 90% or more in the visible light range.

In the modern machining industry, the use of magnetron sputtering technology to produce surface functional films, super hard films and self-lubricating films can effectively improve surface hardness, composite toughness, wear resistance and high temperature resistance and chemical stability, thus improve the service life of coated products.

In addition, magnetron sputtering coating technology also plays an important role in the research of high temperature superconducting thin films, ferroelectric thin films, giant magnetoresistive thin films, thin film luminescent materials, solar cells, and memory alloy thin films.

Magnetron sputtering coating advantages

Magnetron sputtering coating technology has become one of the main technologies of the industrial coating due to its remarkable advantages:

(1) Simple operation and easy control. In the coating process, if the sputtering conditions such as working pressure and electric power are relatively stable, the deposition rate is relatively stable.

(2) The deposition rate is high. When depositing most of the metal, especially the high melting point metal and oxide, such as tungsten, aluminum TiO2 and ZrO2 film, it has a high deposition rate.

(3) Low temperature of the substrate. Compared to two-pole sputtering or thermal evaporation, magnetron sputtering reduces the heating of the substrate, which is quite advantageous for achieving the sputter coating of the fabric.

(4) The sputtered film is strong. The sputtered film has excellent adhesion to the substrate and its mechanical strength is also improved.

(5) The sputtered film is dense and uniform. From the photomicrograph, the surface morphology of the sputtered film is fine and uniform.

(6)The sputtered films all have excellent properties. For example, sputtered metal films generally achieve good optical properties, electrical properties, and certain special properties.

(7) Easy to mass produce. The magnetron source can be expanded as required, so large-area coatings are achievable. In addition, sputtering can work continuously, and the coating process is easy to control automatically, so that the industrial assembly line can be realized.

(8) Environmentally friendly. Conventional wet plating produces waste liquid, waste residue, and exhaust gas, causing serious pollution to the environment. The magnetron sputtering coating method has high production efficiency while does not cause environmental pollution.

Please visit https://www.sputtertargets.net/ for more information.

How to make the phone case of gradient color like Huawei P20?

Gradient color is popular in 2018

It’s overwhelming how many smartphone models are currently available on the market today.  However, as for the color of the phone, what get are the same old black, white, silver and gray, in glossy or matte.

Well, recently an exciting new trend has emerged. The Huawei P20 series let people see the optimal color design and professional photography. A few months ago, Huawei launched the P20 in Twilight, and the dual-tone gradient inspired by the Aurora Borealis made people feel excited.

Huawei P20
Huawei P20

Before that, HTC also introduced the two-tone gradient scheme. Although it does not offer the popular Twilight color scheme, it does bring us a few appealing options with its latest flagship device.

HTC U11
HTC U11

Samsung has also jumped on board the gradient crazy. The Korean tech giant has unveiled a new version of its Galaxy A9 Star in China which features a sleek purple gradient.

Galaxy A9 Star2
Galaxy A9 Star2

Well, these are just a few examples to show that gradient color is the fashion of the year 2018. Are you curious about how to achieve this kind of gradient color? Is it difficult?

Film coating-Physical vapor deposition

Actually, all the color of the shell is about film coating. A cellphone is made from a variety of metals, with the most common being aluminum alloys, lightweight materials commonly found in the phone case. And the film coating is to apply a colored film on the phone case.

Physical vapor deposition is the most widely used film coating technology. Under vacuum conditions, the surface of the material (usually referred to as the sputtering targets or evaporating pellets) is vaporized into gaseous atoms by physical methods, and is then deposited on the surface of the substrate to form a thin film. The main methods of physical vapor deposition include vacuum evaporation, sputtering coating, plasma coating, ion plating, and molecular beam epitaxy.

How to coat the gradient color

PVD can coat gold, brass, rose gold, silver white, black, smoky, copper, brown, purple, blue, burgundy, bronze and other colors on stainless steel, copper, zinc alloy and other metals. There are many choices and the price is affordable, compared to pure gold or other pure metals. (PVD Coating Materials.pdf) You can refer to our previous article for more information: Introduction to PVD Coatings.

By controlling the parameters of different targets and thickness of the deposited film, the film exhibits different colors (the gradation colors mentioned above) under the reflection, refraction and interference of light. Specifically, in the plating furnace space, bombard a specific sputtering target with ultra-high speed electrons; use a certain mask to cover a part of the ion cloud so that only the other part of the ion cloud can be attached to the substrate and forms a very thin layer of nano-plating; control the thickness of the coating to form a nanometer thickness difference; then spray the background color.

For more information, please visit https://www.sputtertargets.net/.

Introduction to PVD Coatings

What is PVD coating technology

PVD, or physical vapor deposition, is an advanced surface treatment technology widely used in the world. Under a vacuum condition, utilize the gas discharge to separate the gas or the evaporated substance, then accelerate the gas ion or the evaporated atoms to bombard the substrate and deposit a film. PVD film has fast deposition speed as well as strong adhesion, good diffraction, and wide application range.

PVD coating colors

PVD can coat gold, brass, rose gold, silver white, black, smoky, copper, brown, purple, blue, burgundy, bronze and other colors on stainless steel, copper, zinc alloy and other metals. There are many choices and the price is affordable, compared to pure gold or other pure metals. (PVD Coating Materials.pdf)

PVD Coating Materials and Their Characteristics
PVD Coating Materials and Their Characteristics

Applications

PVD technology is widely used in the processing of door and window hardware, lamps, jewelry, handicrafts, and other decorative products.

PVD is now quite popular in the hardware field, and many of the world’s leading hardware manufacturers have begun to develop PVD products and mass production.

PVD for molds and precision parts

In recent years, PVD coating technology has been applied more and more in the work surface strengthening treatment of molds. Its outstanding advantages are that it can effectively improve the service life of the mold, and at the same time reduce the coating temperature to about 250 °C ~ 500 °C, which can reduce the deformation of the workpiece. The PVD composite coating has excellent performance and has potential applications that cannot be underestimated. One of the main applications of PVD technology in the mold industry is TiN coating.

PVD & CVD

There are currently two coating methods commonly used in production: physical vapor deposition (PVD) and chemical vapor deposition (CVD). The former has a deposition temperature of 500 ° C and a coating thickness of 2 to 5 μm; the latter has a deposition temperature of 900 ° C to 1100 ° C, a coating thickness of 5 to 10 μm, and the device is simple and the film is uniform.

Previously, most cemented carbides are coated by CVD. However, since the deposition temperature is high, the cemented carbide coated by the CVD method,  a brittle decarburization layer (η phase) is easily formed between the coating layer and the substrate, resulting in brittle fracture of the blade. In the past decade or so, with the advancement of coating technology, the cemented carbide can also adopt the PVD method.

Development of cemented carbide coatings

Coating refers to the application of a thin layer of wear-resistant, refractory metal or non-metallic compound on the substrate of cemented carbide or high-speed steel by vacuum evaporation and sputtering.

A good coating material is required to have high hardness, good wear resistance, stable chemical properties, no chemical reaction with the workpiece material, heat and oxidation resistance, low friction factor, and strong adhesion to the substrate. However, a single coating material is difficult to meet the above requirements. Therefore, the development of cemented carbide coating materials has entered a new stage of thick film, composite film and multi-component coating.

The most mature and widely used cemented carbide coating material is TiN, but the bonding strength of TiN and the substrate is less than that of TiC. TiC coatings have high hardness and wear resistance, and good oxidation resistance, but they are brittle and not resistant to impact. Both of these kinds of coatings have advantages and disadvantages, and TiCN combines their merits.

TiCN coating
TiCN coating

Combine 1)the newly developed multi-component, ultra-thin TiCN, TiAlN coating, 2)TiC, TiN, Al2O3 coatings, and 3)a new anti-plastic deformation matrix can significantly improve the toughness, bond strength of the coating to the substrate, and wear resistance of the coating. At present, the technology of coating diamond film on the cemented carbide substrate is successfully realized, and the performance of the tool is comprehensively improved.

TiAlN, CrN, and TiAlCrN are also new materials for cemented carbide coatings developed in recent years. The chemical stability and oxidation resistance of TiAlN are good. Compared with TiN, the tool life can be improved by 3 to 4 times when processing high alloy steel, stainless steel, titanium alloy and nickel alloy with TiAlN.

CrN is a titanium-free coating with good chemical stability and no sticking. It is suitable for cutting titanium and titanium alloys, copper, aluminum and other soft materials.

TiAlCrN is a gradient structure coating, which not only has high toughness and hardness, but also has a small friction factor. It is suitable for milling cutters, hobs, taps and other tools, and its cutting performance is obviously better than TiN.

In addition to the above new coatings, there are some coatings with specific functions, such as MoS2, DLC lubricated coatings, which have a small friction factor (0.05) and are suitable for coating tools such as taps and drills to improve chip evacuation performance.

For more information, please visit https://www.sputtertargets.net/.

Introduction to Physical Vapor Deposition Technologies

Thin Film Deposition

Thin film deposition technology refers to the preparation of thin films on the surface of materials used in the fields of machinery, electronics, semiconductors, optics, aviation, transportation and etc., in order to impart certain properties (such as heat resistance, wear resistance, corrosion resistance, decoration, etc.) to these materials.

The two most common forms of thin film deposition techniques are physical vapor deposition (PVD) and chemical vapor deposition (PVD).

Physical Vapor Deposition —PVD

PVD is a process that achieves the transformation of the atoms from the source materials to the substrate to deposit a film by physical mechanisms such as thermal evaporation or sputtering.

PVD includes evaporation, sputtering and ion plating.

Evaporation

Evaporation is a common method of thin-film deposition. It is also called vacuum evaporation because the source material is evaporated in a vacuum. The vacuum allows the vapored particles to travel directly to the substrate, where they condense and deposit to form a thin film.

Evaporation (PVD)
Evaporation (PVD)

Sputtering

Sputtering is a physical vapor deposition (PVD) method of thin film deposition. It is a process whereby particles are ejected from a solid target material (sputtering target) due to the bombardment of the target by energetic particles.

Sputtering (PVD)
Sputtering (PVD)

Ion Plating

Ion plating is a physical vapor deposition (PVD) process which uses a concurrent or periodic bombardment of the substrate, and deposits film by atomic-sized energetic particles.

Ion Plating (PVD)
Ion Plating (PVD)

Characteristics of the main physical vapor deposition method

SAM Sputter Target Evaporation Sputtering Ion Plating
Particle energy eV 0.1-1 1-10 0.1-1
Deposition Rate um/min 0.1-70 0.01-50 0.1-50
Adhesion Poor Good Very Good
Density Low High Very High

Among the above three methods, although Ion plating’s film adhesion and density are better, due to technical limitations, the other two methods (evaporation and sputtering) are currently more widely used. In general, sputtering is the best PVD technology.

Stanford Advanced Materials (SAM) is one of the most specialized sputtering targets manufacturers, please visit https://www.sputtertargets.net/ for more information.

Copper Sulfide Sputtering Targets Are The Best Sputtering Materials

Sputtering is a thin film deposition process in the modern technology world of CDs, semiconductors, disk drives and optical devices industries. Sputtering is the process at an atomic level, where the atoms are automatically sputtered out from the sputtering materials and then be deposited on another substrate, such as a solar panel, semiconductor wafer or optical device. It is an effect of the severe bombard of the high energy particles on the target.

In general, sputtering occurs only when kinetic energy is said to be bombarding particles at very high speeds, which is much higher than a normal thermal energy. At the atomic level, this makes thin film deposition more precise and accurate than that by melting the source material using conventional thermal energy.

Copper Sulfide is the best material for Sputtering Targets. It can be molded into the shape of Plates, Discs, Step Targets, Column Targets and Custom-made. Copper Sulfide is a combination of two materials—Copper and Sulphur. The chemical name of the product is CuS, which offers you the Copper Sulfide product with more than 99 percent purity.

 

CopperCyprus is the original source material for the chemical element Copper. The people of Middle East initially discovered it in 9000 BC. “Cu” is the canonical chemical symbol of copper.

 

SulfurWhereas Sulfur, otherwise known as sulphur, is first introduced in 2000 BC and discovered by Chinese and Indians. It is a chemical name originated from the Sanskrit word ‘sulvere’, and the Latin ‘sulfurium’. Both names are for sulfur.

 

Copper Sulfide metal discs and plates are highly adhesive and resistant against oxidation and corrosion. Using Copper Sulfide sputtering targets to deposit thin films will not produce highly reflective and extremely conductive films, but can also extensively increase the efficiency of the source energy.

So to achieve the desired noticeable result in a sputtering deposition, the built-up process used to fabricate the Sputtering Targets should be critical. A Copper Sulfide targeted material will give the best result. However, material like only an element, alloys, mixture of elements, or perhaps a compound can be used for the purposes.

For more information about sputtering targets, please visit http://www.sputtertargets.net/.

Requirements of ITO sputtering targets for LCDs

After a long period of development, the quality of liquid crystal displays (LCDs) continues to increase, and the cost continues to decline. This means that LCDs have higher requirements for ITO sputtering targets. Therefore, in order to keep up with the development of LCD, the future development trend of ITO targets is as follows:

Liquid crystal displays
Liquid crystal displays
Lower resistivity

In recent years, liquid crystal displays have been moving in a more and more refined direction, and with the upgrade of drivers, a transparent conductive film with lower resistivity is required. Therefore, the resistivity of their raw material—ITO target—is also required to be lowered.

Increase target density

When the target density is low, the surface area for effective sputtering is reduced, and the sputtering speed is also lowered. The high-density target has uniform surface, and can obtain low-resistance film. In addition, the density of the target is also related to its service life, and the high density target generally has a longer life. This means that increasing the density of the target not only improves the film quality, but also reduces the cost of the coating, so it must be the direction for the future development of ITO targets.

Larger size

Now that the LCD screen is getting bigger and bigger, correspondingly, the size of the ITO target has to be larger. However, there are still many problems to be solved in large area coating. In the past, people weld small targets together and splice them to achieve large area coating. But the joints were likely to cause a drop in coating quality. In order to solve this problem, the size of ITO sputtering target is required to be larger in the future. This is also a big challenge for the ITO target industry.

Higher use ratio

Planar targets are still one of the most used types of sputtering targets. But one of the deadliest disadvantage of planar targets is the low use ratio. People may develop other types of ITO target, such as rotatory targets and cylindrical planar targets in the future to increase target utilization.

Please visit https://www.sputtertargets.net/ for more information.

Working principles of a resistive touch screen and a capacitive touch screen

resistive touch screen and capacitive touch screenResistive screens and capacitive screens are the two main kinds of mobile screens on the market today. Generally speaking, resistive screen phones can be operated with a finger or a stylus; while capacitive screen phones can only be operated with fingers and cannot be operated with ordinary stylus, but we can use a dedicated capacitive screen stylus to substitute the finger to operate; while the resistive screen phone can be operated with a finger or a stylus. Why do they have such a difference? Is it related to their working principle? Let’s SAM Sputter Targets answer it for you.

Continue reading “Working principles of a resistive touch screen and a capacitive touch screen”

Advantages and Disadvantages of Pulsed Laser Deposition (PLD)

Pulsed laser deposition is one of the methods of thin film preparation, and several others include chemical vapor deposition, material sputtering, and etc. Pulsed Laser Deposition (PLD), also known as Pulsed Laser Ablation (PLA), uses a laser to bombard the surface of the target, raising its surface temperature and further producing high temperature and high pressure plasma ( T>104K), depositing on different substrates to form a film.

Advantages

1 It is easy to obtain multi- component film that is of the desired stoichiometric ratio by PLD.

2 It has high deposition rate, short test period and low substrate temperature requirements. Films prepared by PLD are uniform.

3 The process is simple and flexible with great development potential and great compatibility.

4 Process parameters can be arbitrarily adjusted, and there is no limit to the type of PLD targets. Multi-target components are flexible, and it is easy to prepare multilayer films and heterojunctions.

5 It is easy to clean and can prepare a variety of thin film materials.

6 PLD uses UV pulsed laser of high photon capability and high energy density as the energy source for plasma generation, so it is non-polluting and easy to control.

 Pulsed laser deposition

Disadvantages

1 For quite a number of materials, there are molten small particles or target fragments in the deposited film, which are sputtered during the laser-induced explosion. The presence of these particles greatly reduces the quality of the film.

2 The feasibility of laser method for large area deposition has not been proved yet.

3 Average deposition rate of PLD is slow.

4 In view of the cost and deposition scale of laser film preparation equipment, it seems that PLD is only suitable for the development of high-tech fields such as microelectronics, sensor technology, optical technology and new material films.

 

Stanford Advanced Materials (SAM) Corporation is a global supplier of various sputtering targets such as metals, alloys, oxides, ceramic materials. Please visit our website https://www.sputtertargets.net for more information.