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Design films and touch panels are often laminated to concave surfaces, but functional films such as shatterproof and antireflection are often laminated to the convex side.
In either case, it is difficult to apply without air bubbles or wrinkles along the bent cover, and it is necessary to search for the conditions while trying the actual product.

The photo below is an example of actually pasting a film on curved glass.

A polarizing plate is attached for easy understanding.

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An example of this is laminating a film on glass with a large R, but we also have a prototype of laminating on a small R, such as inside a smartphone cover glass with curved sides.

In addition to laminating the film touch panel on the display side, we hope that it can be used for applications such as pasting decorative films as a printing alternative to the back glass.

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As a direct bonding method, we have experience in OCA and OCR respectively. A suitable construction method can be selected according to the shape, etc.

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Lamination to curved surface

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Of the bent covers, the shape that is made by bending one plate is called the 2.5D shape. Since the shape of glass can be processed by thermal bending, we often see smartphones with 2.5D cover glass.

The figure is an example of a 2.5D cover.

"Part 1" is a large size with a long side of about 1,000 mm, and it bends greatly in the middle.
"Part 2" is a form often seen on smartphones. Left and right are curved.

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These 2.5D cover glasses have a higher design than ordinary flat cover glasses (2D cover glasses), but it is difficult to laminate touch panels, displays, decorative films, surface protection films, etc.

Please refer to "2.5D Lamination" for laminating glass LCDs, etc. and "2.5D Lamination" for laminating decorative films and film touch panels.

2.5D has various shapes, curved parts R, height as a materials, etc. Since it is not possible to easily judge "this shape can be laminated" or "this size is difficult", the engineers will consider the optimal laminating material / laminating method for each consultation. increase.
After all, extreme shapes (R is tight, size is large, etc.) are difficult, and we may give up at the time of examination, but the laminating machines and methods are evolving day by day. We will continue to challenge difficult shapes.

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Ings Shinano's bonding technology can be broadly divided into roller lamination and vacuum bonding.
Since each has its own characteristics, we are considering and applying appropriate laminating technology according to the content of bonding.

We will introduce the outline of each method, application examples and restrictions.

Roller Lamination (Atmospheric bonding)

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As for the alignment method, many machines perform camera alignment.
The camera recognizes each of the laminating material and the adherend, moves the stage, and rolls the roller from the film side. Since the roller is applied, the adherend is a hard rigid plate, and the film side is a mesh material, which is a stage where the pressure of the roller is transmitted.

In camera alignment, in addition to external shape recognition, various reference points can be set, such as recognition of the printed opening of the cover glass, recognition of alignment marks and patterns in the panel. We can perform alignment according to the location we want to manage, such as dimensional tolerance from the outer shape and dimensional tolerance around the screen display.
Please contact us for the size and shape of the recognition pattern that can be supported.

For large size bonding such as 1,000 x 500 mm, the laminating will be based on the external shape. Pay attention to the dimensions of the non-reference plane, as the dimensional tolerance of the member is added to the device accuracy of ± 0.3 mm.

Since the load is applied by a roller when pasting to the atmosphere, it is basically laminating between flat surfaces.
If the material has irregularities, it is difficult if the sticking surface has a convex shape, but it may be possible to handle it if it is a non-sticking surface.
It is difficult to laminate on a curved surface by atmospheric laminating, but it may be possible depending on the shape, such as a very gentle R.

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Vacuum bonding

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Features of OCA

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The advantages over OCR are that it is easier to handle than OCR, where the resin sticks out, the thickness is uniform in the plane, and there is little variation between individuals.
On the other hand, compared to OCR, it requires more thickness to absorb the printing steps on the cover glass. Also, it seems that the cost competitiveness is a little inferior because it is necessary to make the adhesive material into a sheet and cut it into the required shape.

OCA has a large number of products from various manufacturers, mainly acrylic and silicon. In addition, there is also a type that can obtain higher adhesive strength by irradiating UV or applying heat after laminating to promote the reaction, and select it according to the application.

About the process

In the OCA method, a tape-processed adhesive is attached to one panel and the other panel is laminated. Depending on the material, rollers may be laminated under atmospheric pressure, or workpieces may be laminated in vacuum. We have various laminating devices. In addition to laminating flat surfaces, we are also working on laminating curved surfaces.

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