In the medical device industry, recent advancements in increased miniaturization have unlocked a suite of new applications. However, as devices get smaller, it becomes more difficult to create vacuum-tight hermetic seals that protect sensitive electronic parts from damaging elements like moisture, heat, vibrations, and pressure.
A new sealing technology known as Glass Micro Bonding has been developed to enable miniaturization in hermetic packaging. This technology enables the development of next-generation devices with entirely new features, such as full transparency for advanced optical functions as well as completely wireless signal transmission.
The Limits of Traditional Sealing Technology
Manufacturers of electronic assemblies generally have two vastly different technologies available when sealing their components: they use either adhesive-based bonding or hermetic bonding.
Adhesive-based sealing uses glue, epoxy, or injection molding to create a seal. The advantage of this process is that it can take place at room temperature. However, the organic nature of these adhesives makes the seals non-hermetic and therefore mostly unsuitable for long-term protection. Simply put, they can wear out over time, especially in harsh conditions. This typically rules out adhesive-based bonding in medical applications, where reliability is critical.
In contrast, hermetic bonding uses only inorganic materials such as glass, metal, or ceramics, creating a truly hermetic and vacuum-tight seal. Direct hermetic bonding creates a durable solution for reliability-critical applications. Commonly known hermetic sealing technologies like glass-to-metal and ceramic-to-metal sealing are extremely effective at creating reliable vacuum-tight seals, but simultaneously carry certain size limitations when it comes to miniaturization. While it is possible to create hermetic seals using these technologies that are as small as a few millimeters, the demand for extreme miniaturization and the need for additional functionality (such as digital connectivity) are pushing the limitations of existing processes.
Miniature Wafer-Level Bonding for Medical Applications
Glass Micro Bonding is a wafer-level process that allows the reliable packaging of even miniaturized electronics or MEMS by directly bonding two or more glass wafers without any interface materials. The all-glass wafer-level chip-scale packaging (WLCSP) technology unlocks significant potential in many intriguing applications, including medical implants, 3D MEMS packaging, and other reliability-critical electronic and optical devices.
Glass Micro Bonding entails using an extremely precise laser to fuse glass to glass by melting only the cross section where the glass meets—an area of just a few microns—while leaving all other surfaces untouched. The extremely small and precise seal areas add negligible bulk to the electronic components. This one-step manufacturing process does not require any type of adhesive or additive materials and forms a true direct hermetic seal between the glass wafers.