Protecting electronics from harsh environment conditions
In the current industry landscape, there are two main approaches for sealing of electronic assemblies: adhesive-based bonding and direct hermetic bonding. Adhesive-based bonding uses glue or epoxy to create a seal and can be done at room temperature. However, the organic nature of these materials makes them non-hermetic and therefore unsuitable for long-term protection as they wear out over time. This breakdown process can be exponentially accelerated if exposed to harsh environment conditions, ultimately making adhesive-based bonding unsuitable for reliability-critical medical applications.
In contrast, direct hermetic bonding offers a true hermetic and vacuum-tight seal, delivering the best possible protection for electronics in reliability-critical applications. This makes it the ideal choice for complete electronics protection. Only inorganic materials are used – such as glass, metal, and ceramic – which offer durable seal integrity and remain reliably intact, even under extraordinarily harsh environmental surroundings. Direct hermetic bonding offers significant advantages, however, commonly known hermetic sealing technologies such as glass-to-metal or ceramic-to-metal sealing technologies have certain size limitations. While they can be made in very small form factors (as small as a few millimeters), new demands in cutting-edge devices for extreme miniaturization as well as RF functionality pose a challenge as the boundaries of miniaturization continue to be tested.
Glass Micro Bonding is an innovative process that opens new doors for wafer-scale sealing of electronics with all-glass hermetic electronic packages. The hermetic seal is formed 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. 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.
The extremely small and isolated area heated by Glass Micro Bonding to form the seal allows even the most heat-sensitive electronics and sensors to be vacuum-sealed in an all-glass hermetic package at room temperature. This opens new doors for Glass Micro Bonding to be used for hermetic sealing in microfluidic devices or sensors that may contain a sensitive organic layer or coating applicable to their specific function.
Glass Micro Bonding is a simple, straightforward process that does not require any additive materials and can be performed with new glass types that offer excellent biocompatibility. This makes it an ideal technology for medical applications in which biocompatibility is of paramount importance – particularly for implantable devices. There is also a decreased likelihood of reactions with other materials. Such a reaction could cause materials to break down, leading to device malfunction. In addition, the extremely small and precise seal areas add negligible bulk to the electronic components.
While the technology allows for the use of wafers with hermetically sealed-in through-glass vias, a notable advantage of Glass Micro Bonding is that its transparent glass encapsulation can even eliminate the need for wired connections – radio frequencies (RFs) can travel through the all-glass package. This can reduce both bulk and complexity in device designs while also allowing devices be Internet-connected by emitting and receiving over-the-air data signals. This is extremely intriguing in medical device and implantable applications, as RF can be used for live monitoring as well as reprogramming or updating a device without removing it from its existing setting. Glass Micro Bonding also enables sealed electronics to be combined with chip-based optical components to create optical devices for sensing, imaging, or telecommunications applications.
Components sealed with this new technology can be as small as a few cubic millimeters. The technique is very flexible and can be performed on a chip-scale all the way up to wafers as large as 12 inches, making it simple and cost-effective to scale up for high-volume manufacturing.
Revolutionary steps already being taken in medical and aerospace settings
Glass Micro Bonding creates an extremely robust and reliable seal that encapsulates sensitive electronics, supporting long-term reliable electronic device operation. The technology is quickly becoming established in applications where failure is not an option and ultra-miniaturization is an advantage or requirement, particularly for medical devices and implants as well as aerospace settings.
Israel-based Nano Retina is using Glass Micro Bonding to seal and protect electronics in a retinal implant device designed to help restore vision in individuals with blindness from retinal degenerative disease. It was key that the sealing technology not only be clear so it can be used in the eye, but also extremely low profile while maintaining strength and reliability. The implantable device, which works with a set of eyeglasses worn by the patient, replaces the functionality of damaged photoreceptor cells in the eye and creates electrical stimulation that activates remaining healthy retinal cells.
Further adding to a reputation of reliability is the use of Glass Micro Bonding in electronic components onboard satellites, where repair or replacement processes of any kind are typically not an option due to inaccessibility in space. Glass Micro Bonding can support the longevity of key components for the lifetime of the satellite and also withstand the extreme conditions present during launch and orbit. The European Space Agency is using Glass Micro Bonding for robust packaging of an optical sensor with sealed-in electrical feedthroughs, which has already seen success in several test projects.