Surface Treatment

Surface treatment using 172 nm Excimer technology is an advanced process that employs high-energy ultraviolet (UV) light to modify the properties of material surfaces. This technique is highly effective for cleaning, micro-structuring, and enhancing adhesion without causing thermal damage to the substrate. Industries such as electronics, medical devices, automotive, and aerospace benefit from Excimer technology due to its precision, efficiency, and ability to treat delicate materials. By providing uniform and controlled surface modification, Excimer technology ensures high-quality results, supporting the production of superior, high-performance products.

Excimer vs. Corona and Plasma

Unlike the better-known processes such as plasma and corona, excimer lamps emit little or no heat and are therefore considered "cold" radiation sources.

The surface to be treated is therefore not subjected to any thermal stress. Since the main effect of the treatment is based on photons, the excimer treatment is very uniform and does not result in any microscopic changes to the surface. Surface structures, such as those present in membranes, are preserved and are not damaged.

Therefore, the process is much gentler and a cleaning method that can also be used on sensitive surfaces such as monofilms and is particularly useful for the display and semiconductor industry, sensor technology, the field of printed electronics and for battery production.

Surface Cleaning

Surface cleaning is an essential intermediate production step in most industrial applications to remove production-related contaminants from surfaces.

In excimer surface cleaning, the material to be cleaned is irradiated with short-wave VUV (Vacuum Ultra Violet) light with a wavelength of 172 nm. Due to the high photon energy of 7.2 eV, organic substances such as dust, fats and oils, as well as oxide layers in some cases, can be broken up and disintegrated into molecular fragments.

During this process, ozone is generated in the air film between the excimer module and the material, which oxidizes and dissolves molecular fragments. The result is a clean surface.

Surface activation

In addition to surface cleaning, Excimer technology is used for surface activation.

Surface activation is the process by which a layer with better bonding properties is exposed on the surface of substrates (glass, metal and plastics). This significantly increases the printability, coatability and bondability of the substrates.

Surface activation leads to a measurable increase in quality, especially in industrial applications such as printing, coating and bonding.

Surface activation uses 172 nm excimer radiation to remove impurities or passivation layers while simultaneously forming electronegative molecular groups. This combination leads to an increase in surface energy, also called surface tension.

Surface tension defines the quality of wettability. It is measured via the contact angle between the surface and the liquid (inks, coatings, adhesives) and can be determined with the aid of test inks, for example: the smaller the contact angle between the liquid and the surface of the substrate to be wetted, the better the adhesion, the clearer the printed image, the more brilliant the colors, etc. The surface tension is determined by the surface of the liquid.

Adhesive-based joining

Among the various joining techniques, adhesive-based joining of components is becoming increasingly popular. The decisive factor for good bonding is the adhesion of the adhesive to the surfaces to be bonded. Especially with plastic, metal and glass surfaces, good adhesion is not inherent. By means of pretreatment using excimer technology, the adhesion of adhesives to surfaces is greatly increased. The pretreatment step is gentle, uniform and cold and leaves no surface defects. Typical applications are found wherever large areas have to be bonded, e.g. when bonding films, components in the automotive sector or when joining two wafers in the semiconductor industry.

Optical bonding

A special variant of adhesive-based bonding is optical bonding, in which a full-surface, transparent adhesive bond is produced by means of a liquid adhesive (LOCA process). This process is used to bond the display, touch sensor and cover glass together in the course of manufacturing display solutions, which offers several advantages:

Color brilliance and contrast of the display solutions are significantly increased because filling the gap between the various display elements with adhesive reduces annoying reflections. In addition, the adhesive layer between the layers increases resistance to mechanical influences such as impacts and shocks.

However, all this can only be achieved if the adhesive adheres perfectly to the surfaces and bonds them permanently and stably. To ensure this, the surfaces can be pretreated with excimer irradiation during the manufacturing process. In this process, the surfaces are activated on the basis of radiation, which leads to homogeneous and optimized adhesion properties of the adhesive.

Photobonding

The lesser-known process of excimer-assisted photobonding is also used to join two surfaces, but is a completely adhesive-free and heat-free alternative. It uses radiation-based surface activation to allow two surfaces to be bonded together with low pressure. This process is particularly suitable for joining materials with optical functions, such as silicone, glass, PDMS, PC, PMMA or COP, i.e. materials with a high optical surface quality that must be maintained, or interfaces that must not contain foreign substances (such as adhesives).

Excimer-based optical bonding is therefore ideal for manufacturing processes of sensors, components with optical function, biomedical components (lab-on-chip), displays and photovoltaic components.

You are interested and would like to evaluate the excimer technology for your application?

Contact us, we offer you different possibilities to evaluate the excimer technology for your specific application purposes.

First of all, our engineers and staff are at your disposal for a well-founded consultation. In a detailed discussion you will get answers to your questions.

In the next step, we determine all points of your catalog of requirements and clarify the details regarding the appropriate materials and exact production steps, your targets and expectations. This is followed by a further coordination phase up to the final conception of the project including a quotation.

Ushio test laboratory at our site in Germany

If your application is predestined for excimer treatment and you decide to use it, we also offer to treat samples of the corresponding materials in our in-house test laboratory according to your catalog of requirements. If the Corona situation again makes it possible, we welcome you on site for these tests. We will provide you with test reports in any case and define adaptation possibilities together with you, should these be necessary or desired.

If you would like to have final tests at your site, we also offer the possibility, under certain conditions, to borrow excimer test modules and to test them directly in the respective production steps at your site with our expert advice.

And even after the start of the project, we continue to advise and support our customers. We help, if necessary, with the practical integration of the modules into your production line. And should small adaptations or modifications be necessary for optimal integration, we also have the appropriate know-how.