Atmospheric Pressure Dielectric Barrier Discharge Plasma-Enhanced Optical Contact Bonding of Coated Glass Surfaces

Abstract

This paper reports on plasma-enhanced bonding of optics surfaces coated with highly sensitive functional layers using surface preparation by a dielectric barrier discharge (DBD) plasma. The samples to be bonded were treated with a DBD in diffuse mode at atmospheric pressure for 30 s which is applied directly to the sample surface, then joined with the aid of de-ionised water and cured subsequently. The plasma treatment itself already increased the shear strength achieved by a factor of two compared to classical wringing or direct contacting, while the curing process led to a further increase by a factor of up to five, depending on curing temperature. The observed enhancement of shear strength can be attributed to DBD plasma-induced cleaning and most likely additional activation of the surface as verified by contact angle measurements. Since the impact of the used plasma on the surface is quite gentle in comparison to other bonding processes or other plasma-based processes reported in the literature, a destruction of the treated functional layer is avoided. This advantage makes it possible to bond even optics surfaces coated with sensitive materials.

Low‐temperature bonding of glasses: The role of plasma‐engrafted surface amino groups

“…This method is also advantageous in processing large area due to its simple equipment compared to the vacuum plasma treatment. However, it has been rarely investigated that how the atmospheric pressure plasma treatment affects the bonding strength of glass 22,23 . Further, the chemical characteristics after the plasma treatment (e.g., terminal groups) remain unclear.…”

“…However, it has been rarely investigated that how the atmospheric pressure plasma treatment affects the bonding strength of glass. 22,23 Further, the chemical characteristics after the plasma treatment (e.g., terminal groups) remain unclear. Therefore, it is worthwhile to develop a bonding technique with understanding of the chemical effect on glass surface by atmospheric pressure plasma treatment.…”

Atmospheric pressure dielectric barrier discharge plasma-enhanced optical contact bonding of different types of optical glasses

“…Fused silica and borosilicate glasses were already bonded successfully after surface activation via a dielectric barrier discharge (DBD) plasma treatment at atmospheric pressure and a subsequent annealing process [14] or by combination of wet chemically and plasma surface functionalization with N2 or O2 [15]. These methods don't work with metal containing layers as needed for non polarizing beam splitters as described in [18]. That's why the developed process in [18] should be transferred to other substrate materials like N-BK7.…”

“…These methods don't work with metal containing layers as needed for non polarizing beam splitters as described in [18]. That's why the developed process in [18] should be transferred to other substrate materials like N-BK7. The transfer of bonding technologies used for wafers and uncoated optics or glass surfaces to optical components with functional coatings is of great interest.…”

“…The wet-chemical processes were already performed successfully on optical components with dielectric functional coatings, whereas the use of the plasma process has turned out to be problematic due to the fact that the used DBDs and jet plasmas penetrate into the coating material [16,17]. In previous work, a plasmaenhanced process, based on a quasi-homogenous helium DBD-surface activation was designed for fused silica, coated with a metal-containing functional layer [18]. Because borosilicate glasses are used almost more frequently in optical production than fused silica due to their processing properties, it was tested whether the developed process is also suitable for borosilicate glasses (especially boron crown glass) or whether an SiO2 final layer is necessary.…”