Hermetic glass soldered micro-packages for a vision prosthesis

Medical devices implanted in the body must resist environmental stressors over long periods. Prior research has shown that ceramic packages with glass solder can offer high durability. However, no prior work had resolved how to maintain internal dryness in micro-packages under high humidity. This gap motivated the development of a new sealing method. Researchers needed to balance heat during sealing to avoid damaging electronics. The challenge was to create a hermetic seal without exceeding safe temperatures. Existing methods risked warping or cracking the package. The study aimed to address these limitations. A new approach was needed to improve long-term stability. This paper contributes by testing a novel fabrication and sealing technique.

The goal was to evaluate a new method for sealing micro-packages used in vision prosthetics. These devices require long-term hermeticity to protect sensitive electronics. The study aimed to test whether glass solder could maintain a seal under accelerated aging. Researchers focused on preventing moisture intrusion over time. They also wanted to assess the impact of PDMS coating on durability. The method needed to allow high-temperature sealing without damaging the electronics. The study sought to measure humidity levels inside the packages. The ultimate aim was to determine if the design could meet a 5-year lifespan.

The team fabricated micro-packages using alumina ceramics and glass solder. Packages measured 1.2 mm in height and 10 mm in diameter. A custom device was built to control temperature during sealing. The rim was heated to 550°C while the center stayed below 300°C. This prevented damage to the electronics during the process. Packages were backfilled with helium to test hermeticity. A fine leak tester was used to detect any air infiltration. Some devices were coated with PDMS, others left exposed. All were stored at 85°C in water to simulate aging. Humidity sensors were placed inside to track moisture intrusion.

Eight packages were successfully fabricated and tested over 1.5 years. One device failed after an extrapolated 5-year lifetime. Seven maintained humidity below 17,000 ppm throughout the test. Two devices showed constant humidity levels, others increased gradually. The fine leak test confirmed hermeticity at 1×10(-12) atm·cc/s. PDMS-coated devices showed no glass corrosion after a year. Optical and electrical tests confirmed the coating’s effectiveness. The method allowed symmetrical heating without damaging electronics. The results suggest the design can meet long-term stability requirements. The study demonstrated the feasibility of the sealing technique.

The authors propose that the sealing method can achieve long-term hermeticity. They suggest that PDMS coating prevents glass corrosion under high humidity. The study shows that temperature control during sealing is critical. The results indicate that the design can meet a 5-year lifespan. The authors note that humidity levels remained stable in most devices. They propose that the method is suitable for vision prosthetics. The study supports the use of alumina and glass solder in micro-packages. The authors conclude that further testing is needed to confirm long-term performance.