High temperature endurable hermetic sealing material selection and reliability comparison for IR gas sensor module packaging

Infrared (IR) sensor module deploy for hazardous gas leakage detection is crucial to provide and maintain offshore Oil & Gas platform asset integrity and improve operational risk management by avoiding accidental disaster and mitigating risk associated with danger involve in oil production. These sensor modules must remain robust under harsh ambient environment. Hence, designing novel high temperature interconnects material bill of materials (BOM) with compatible barrier metallization [1-2] and robust hermetic sealing material further enhanced sensor reliability. By reducing BOM oxidation degradation at high ambient temperature [3-4], reliability of the sensor is maintained. For this study, the TV (test vehicle, Figure 1) consist of an Alumina (Al
2
O
3
) substrate casing which houses all the active components and is hermetically sealed with a Silicon (Si) die that acts as an IR filter. Laser and seam welding are common method of performing hermetic sealing but they suffer from low throughput issues. An investigative benchmark of various hermetic sealing methods and materials will be discussed in great details, targeting Alumina (Al
2
O
3
) to Silicon (Si) interfaces sealing. Both sealing surfaces have no metallization. Materials such as high temperature low outgassing adhesive, glass frit paste and ceramic paste will be applied on the TV via dispensing or screen printing method and their corresponding hermeticity performance of the sealing interface will be investigated. The silicon filter is 3.7 × 3.7 mm in size and will be mounted on a 3.8 × 3.8mm ceramic substrate casing. TV hermeticity degradation response (base on MIL-STD-883J Method 1014.14 which requires 10
⁻⁹
cc/sec leak rate) is examined after reliability evaluation is conducted, which include Thermal Cycling (TC, −55°C to 250°C, 500 cycles) and High Temperature Storage (HTS, 250°C, 500 hours). The objective of this paper is to report the high temperature reliability performance of various benchmarked sealing materials and understand and document the degradation mechanism and hermeticity response (via MIL-STD leak test) after HTS and TC test at 250°C.