Interpretation of the mystery of fully-fitted OCA optical clear adhesive

1. What is OCA?

OCA (Optically Clear Adhesive) is one of the raw materials of TFT touch screen. It is made of base-free optical acrylic pressure-sensitive adhesive, and then a layer of optical release film is attached to the upper and lower bottom layers to make a double-sided tape. A double-sided tape without matrix material; OCA has the advantages of high cleanliness, high light transmittance, low haze, high adhesion, no crystal points, no bubbles, water resistance, high temperature resistance, UV resistance, etc. Moreover, its thickness is uniform and flat, and the refractive index of OCA is close to that of glass, PC and PMMA. There will be no problems of yellowing, aging, fogging, peeling from adhering surfaces and air bubbles with long-term use.

All in all, it's the material used to make the Touch Panle.

2. How to distinguish between good and bad OCA?

A good quality OCA has this effect.

1). It can reduce glare, reduce the loss of light emitted by LCD or Mini OLED display, improve the brightness of the display, and provide high light transmittance, reducing energy consumption.

2). Increases contrast, especially in bright light; surface connections have higher intensity.

3). Avoid the appearance of Newton's rings.

4). With OCA optical glue, the surface of the product is smoother, without wrinkles, bubbles, impurities, and the display image has little effect.

5). No border, enlarge the visible area; good defoaming effect, high yield of TFT touch screen, no yellowing, good rework.

Poor quality OCA is like this.

1). Dead foam is easy to appear during the gluing process and cannot be defoamed.

2). After sticking the glue, remove the air bubbles, which will easily cause the air bubbles to rebound. Rework is required, which takes time and cost.

3). The glue tends to turn yellow after a period of use.

4). When the protective film of the glue is peeled off, there will be an embossing phenomenon. There will be residual oily glue and surrounding asymmetry.

All in all, we should pay attention to the following points in the process of purchasing OCA dry glue.

Focus on checking for indentations (the material is not allowed to have joints), creases, white spots, foreign objects, pinholes, dents, air bubbles, glue wrinkles.

3. OCA processing technology.

OCA die-cutting factories generally use optical-plastic die-cutting technology, optical-plastic product punching and hole-setting technology, optical-plastic linear bubble position adjustment technology; by purchasing OCA optical-plastic materials, and then according to different customer combination processes for OCA structure design, Pre-processing such as precision die-cutting or slitting, and sales to assembly plants of touch screens or display modules. Downstream manufacturers establish more comprehensive and closer ties.

And according to the different full assembly processes of different customers, the OCA structure design and the preliminary processing such as slitting after precision die cutting are carried out.