AbstractThe Swiss technology allows the single step formation of a joining object composed of glass and a tin based soft solder metallic seal. Robust hermetic seals can be obtained within minutes in a single step and without pre-metallization. Potential uses vary from vacuum glazing sealing to semiconductor packaging applications and is both economical and scalable. The research institute is looking for partners active in packaging, soldering or isolation for license agreements and technical cooperation
DetailsConvential way of glass sealing:
Standard glass sealing is done either by using glass solders (low melting glasses) or multilayer bonding approaches meaning either pre-metallization and soft soldering or formation of a multilayer structure and anodic bonding of the metallic side (typically an Al film) to the glass. Glass soldering is typically carried out at temperatures of 450°C or higher which can cause material and/or compatibility problems. Pre-metallized soldering and anodic bonding of multilayer structures require additional working steps which complicate the process and entail higher cost and failure susceptibility.
New approach with direct hermetic glass-metal sealing:
In vacuum glazing, the glass solder approach as a non-vacuum compatible method could be replaced by activated tin-solder anodic bonding. Thus, many problems associated with the manufacture could be circumvented, opening up the possibility for a new generation in both production and energy efficiency (see figure). Robust hermetic seals can be obtained within minutes in a single step and without pre-metallization.
Implementation and application:
This technology is currently being implemented into a small pilot scale for the fabrication of 0.5m by 0.5m glazings.
The same technology could alternatively be used for but not limited to sealing of PV (Photovoltaics ) elements or OLED (Organic light-emitting diode) display panels and semiconductor / MEMS (Microelectromechanical systems) packaging.
The method is a single step process which means that compared with conventional technology sealed objects can be manufactured with identical or better quality while eliminating an additional production step.
Activated solder anodic bonding combines:
- low process temperature (250°C – 350°C),
- practicability over a large pressure range (from atmospheric to high vacuum)
- rapid bonding times,
- extreme hermeticity and
- uses inexpensive raw materials and technologies.
This combination adds up to a significant advantage in resource and cost effectiveness compared with conventional techniques