Battery coating for rechargable hearing systems
Embodiments of the invention include a method of preventing ferrite migration in a hearing aid including an antenna stack and a battery stack wherein the antenna stack sits on the battery stack, the method comprising the steps of: conformally coating the top and sides of the antenna stack using a conformal coating material; and separately coating all the surfaces of the battery stack using a separate material.
1. A hearing aid device comprising:
a tympanic lens;
a chassis;
a PCM circuit;
an antenna stack positioned in the chassis having a top, sides and a bottom, the antenna stack comprising:
a coil antenna having a first and second side, the first side of the coil antenna forming the top of the antenna stack;
a backing iron having a first and second side, the first side of the backing iron being attached to the second side of the coil antenna, wherein the backing iron is configured to concentrate an electromagnetic field from an external charger toward the coil antenna; and
a spacer having a first and second side, the first side of the spacer being attached to the second side of the backing iron and the second side of the spacer forming the bottom of the antenna stack;
a battery stack, the battery stack being positioned in the chassis, connected to the PCM circuit and comprising:
a rechargeable battery having a first and second side, the first side of the rechargeable battery being attached to the second side of the spacer; and
a printed circuit board attached to the rechargeable battery;
a conformal coating material covering the top and sides of the antenna stack sealing the top and sides of the antenna stack from moisture ingress; and
a second coating material covering the top and sides of the battery and the printed circuit board, sealing the battery stack from moisture ingress,
wherein the spacer of the antenna stack comprises a plastic spacer configured to isolate the battery stack from the backing iron and prevent ferrite electro-migration to the battery stack.
2. The hearing aid device according to claim 1 , wherein the conformal coating material comprises an organic coating material.
3. The hearing aid device according to claim 2 , wherein the conformal coating material comprises Hysol.
4. The hearing aid device according to claim 1 , wherein the second coating material comprises Parylene.