Cochlear implant for an implantable cochlear stimulation system and method of assembly

In a cochlear stimulator system, a cochlear implant comprising:

• an implantable sealed housing comprising a metal feedthrough case having separate sealed top and bottom compartments and metal feedthrough pins extending between the top and bottom compartments and having upper and lower end portions respectively within the top and bottom compartments,
• cochlea stimulation circuitry housed with the bottom compartment and electrically connected to lower end portions of the feedthrough pins, upper end portions of the feedthrough pins being electrically connected to a lead from a cochlear electrode to complete a connection between the stimulation circuitry and the cochlear electrode,
• silicone enclosing upper end portions of the feedthrough pins configured to limit any moisture leaking around the feedthrough pins from the top compartment to the bottom compartment housing the stimulation circuitry to leak rates less than about 1×10−7 atm cc/s, and
• a moisture absorbing material secured within the bottom compartment of the feedthrough case and comprising calcium oxide sufficient in quantity to absorb any moisture released by the stimulation circuitry and any moisture leaking into the bottom compartment of the feedthrough case at the leak rates less than about 1×10−7 atm cc/s and to extend the useful life of the implant.