Encapsulation technique for pressure micro-sensors within humid environments

摘要

Encapsulation technique for pressure micro-sensors within humid environments. The technique consists in inserting the entire chip into a silicone. In this way any rigid link between the sensor element and the outer rigid capsule is avoided, such that the chip is mechanically decoupled giving rise to states of low mechanical force. The immersion of the complete chip in the silicone additionally provides hermetic encapsulation in the protective and inert material which insulates the electrical conductors, the circuits, micro- welds and connecting wires. The use of a photo-curing silicone resin in combination with photolithography processes for protecting the upper part of the surface of the sensor further allows partial and controlled protection. This means that the process is especially suitable for encapsulation of silicon micro-sensors since it makes it possible to leave uncovered the active or sensitive areas of the upper part of the chip, thus preventing any influence by the covering material on the sensitive membrane. <IMAGE>