The total amount of PET films used in the smartphone industry isn’t vast, but they are utilized in many different parts of a phone. Various thicknesses of PET films are required, with each type having different performance requirements and prices. Let’s explore the types of PET films used in smartphones

What is PET Base Film?

PET base film is a versatile packaging film known for its transparency, gloss, good gas and aroma barrier properties, and moderate moisture resistance. Its excellent mechanical properties include superior toughness among all thermoplastics, high tensile and impact strength, and good dimensional stability, making it suitable for printing, bag making, and other secondary processing.

What is Release Film？

Release film is a functional film with PET as the base material and release agent coated on one or both sides of the film, so that it is non-sticky or slightly sticky to specific materials under limited conditions. It has the characteristics of high cleanliness, low release agent transfer, light release force, good solvent resistance, and customizable release force.

Applications of PET Base Film:

Adhesive tapes

Die-cutting

Electronics processing

FPC lamination

MLCC protection

Polarizer protection

OCA protection

PET Films in Smartphone Components:

1 Tempered Glass Protection Film:

Most smartphones have a protective film. Initially, single-layer high-transparency PET protection films were used, later evolving to multi-layer structures like AB glue, which uses around 4 layers of PET base film.

OCA Optical Clear Adhesive requires 2 layers of PET release film. Additional layers are used in the die-cutting process and tempered glass production, adding up to approximately 4 layers of PET base film.

2 .Cover Plates

Manufacturing involves cutting, ink printing, magnetron sputtering for waterproof layers, and protective layers during shipping. This process uses at least 2 layers of PET base film.

3 External Touch Layers (Optional):

Once popular in GFF structures, now mostly replaced by incell or oncell touch layers. GFF structures still used in industrial or large screens require at least 8 layers of PET base film.

4 Full Lamination OCA:

Combining the cover plate or external touch module with the LCM display module using hard-to-hard OCA adhesive requires about 4 layers of PET base film.

Heat Dissipation Artificial Graphite Sheet:

Yousan Technology OCA Optical Adhesive

OCA Optical Adhesive is primarily composed of acrylic pressure-sensitive adhesive and is laminated with release films on both sides. It boasts excellent optical properties, is acid-free, compatible with functional sheet materials (such as ITO, AgNW), offers superior reliability, and has good step absorption characteristics.

Product Applications:

Full lamination of LCD modules and touch panels (TP).

TSP lamination (including G/F/F, G/F, P/F), explosion-proof film lamination, optical compensation film, and polarizer lamination.

5. Touch Modules (Optional):

Depending on the supply chain, some touch module manufacturers, after completing the touch screen, will ship to display manufacturers such as BOE, Tianma, and Huaxing. At this stage, 2 sheets of PU adhesive PET protective film are needed, which must have excellent appearance and degassing effects.

6 Polarizers

or polarizer rolls, the protective film itself requires PET with silicone and release film, necessitating 2 PET sheets. Additionally, the release film of the optical pressure-sensitive adhesive at the bottom also requires 1 PET sheet. During the production of polarizer rolls and die-cut sheets, TAC films, phase difference films, PVA films, and functional coating layers for anti-glare and anti-scratch require high appearance standards, typically needing protective films during processing. These usually involve using PE, CPP, or PET-based protective films, amounting to at least 3-4 PET sheets used in the process. Therefore, polarizers need at least 6 PET base films. Given that LCD displays have two orthogonal polarizers, this totals 10-12 PET base films.7 Rear Cover Explosion-Proof Film:

Non-metallic rear covers require explosion-proof films with various patterns and colors, using at least 3 layers of PET film.

8.Light-Shielding Tape

Light-shielding tape, formerly known as black-and-white tape or simply black tape, is used for bonding the LCD cell and the backlight module (LCM). The process involves printing black ink on PET, coating both sides with acrylic adhesive, and using release films on both sides. Additionally, to save materials, an asynchronous die-cutting machine is used for splicing and cutting, which requires replacing the release film and protective film, using about 5 sheets of PET base film.

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9 Heat Dissipation Artificial Graphite Sheet:

Made using PI polyimide, requiring 2 layers of single-sided PET tape and 3 layers of double-sided PET tape, totaling at least 5 layers of PET film.。

10 Display Screen Frame Adhesive Foam Tape:

Used for bonding the display module and the phone’s middle frame. This process consumes around 3 layers of PET base film.

11 Various Functional Tapes:

Non-metallic rear covers require explosion-proof films with various patterns and colors, using at least 3 layers of PET film.

12 Rear Cover Explosion-Proof Film:

Previously, the back covers of phones were made of metal. With the increase in non-metallic back covers, explosion-proof films are now used. These films are made by creating various textures and printing different colors on a PET base material, which is then laminated onto the back cover using double-sided adhesive. This process, including the base material, release film, and protective film, requires at least 3 sheets of PET,

13 MLCC Multilayer Ceramic Capacitors:

Manufacturing requires coating barium titanate on release film, stacking 300-500 layers, resulting in the use of approximately 2 layers of PET base film.

14 PCB and FPC

production involves dry film etching and hot pressing, requiring at least 2 layers of release film and protective films, totaling around 2 layers of PET

15 Wireless Charging Modules:

Ultra-thin PET double-sided adhesive tape with multiple PET film layers is used, consuming about 4 layers of PET base film per module.

16  Supply Chain Packaging:

Transportation within the supply chain requires various packaging and labeling materials, adding up to roughly 4 layers of PET film.

In total, conservatively estimating, each smartphone requires over 60 sheets of PET film for its various components and manufacturing processes.