Hermetial via seal for thin film battery
Vertical via connections to a battery are hermetically sealed to prevent environmental factors (e.g. moisture, oxygen, and nitrogen) from entering the internals of the battery through porous conductive material filling the vias resulting in reduced battery performance and battery failure.
1. An electrical connection to a lithium battery comprising:
a substrate with a battery side and an external side, the external side having a substrate surface;
one or more vias passing through the substrate;
a porous electrically conductive material filling each of the vias, the porous electrically conductive material having an external via opening on the external side and a battery via opening on the battery side, the battery via opening electrically connected to one or more lithium battery components in the lithium battery;
an electrically conductive seed layer covering the external via opening and penetrating the external via opening a seed layer depth; and
an electrically conductive cap electrically connected to the seed layer,
wherein the seed layer and electrically conductive cap hermetically seal the porous electrically conductive material from environmental factors.
2. A connection, as in claim 1 , where the environment factors include one or more of the following: gases, liquids, nitrogen, oxygen, water, and moisture.
3. A connection, as in claim 1 , where the seed layer depth is less than 20 μm.
4. A connection, as in claim 1 , where the seed layer further covers a region surrounding the external via opening on the external side surface of the substrate.
5. A connection, as in claim 4 , where the region surrounding the external via opening overlaps the external side surface of the substrate an overlap distance equal to at least 50% the diameter of the via.
6. A connection, as in claim 1 , where the seed layer comprises any one or more vacuum deposited materials within the seed layer depth of the external via opening as follows: Titanium (Ti), Ti/Cu, Ti/Cu/Pt, Ti/Pt, Ti/Pd Ti/Cu/Pd Ta/TaN, Ti/W, and Ti/TiN.
7. A connection, as in claim 6 , where the injected materials are injected into the external via opening by any one of the following: a vacuum deposition method, sputtering, atomic layer deposition (ALD,) evaporation, Chemical Vapor Deposition (CVD,) Plasma Enhanced Chemical Vapor Deposition (PECVD,) Physical Vapor Deposition (PVD,) a wet deposition, a dry deposition, a radiation with a shadow mask, and lithography.
8. A connection, as in claim 1 , further comprising a thicker conductive layer between the seed layer and the cap.
9. A connection, as in claim 8 , where the thicker conductive layer is an electroplated layer with a plated thickness of below 5 μm.
10. A connection, as in claim 1 , where the cap is one or more of the following: a cap electroplated metal, a dropped solder ball, solder disposed by Injection Molded Solder (IMS,) and stencil printed solder paste.
11. A lithium battery comprising:
a cathode made of a first lithium compound, the cathode connected to a cathode current collector;
an anode made of a second lithium compound, the anode connected to an anode current collector;
an electrolyte between the cathode and anode;
a substrate with a battery side and an external side, the external side having a substrate surface;
a cathode via passing through and perpendicular to the substrate;
an anode via passing through and perpendicular to the substrate;
a porous electrically conductive material filling each of the anode and cathode vias, the porous electrically conductive material in each via having an external via opening on the external side and a battery via opening on the battery side, the battery via opening of the anode via electrically connected to the anode and the battery via opening of the cathode via electrically connected to the cathode;
a cathode electrically conductive seed layer covering the external via opening of the cathode via and penetrating the external via opening of the cathode via a cathode seed layer depth;
an anode electrically conductive seed layer covering the external via opening of the anode via and penetrating the external via opening of the anode via an anode seed layer depth;
an electrically conductive cap electrically connected to each of the cathode seed layer and the anode seed layer,
wherein the seed layer in combination with the electrically conductive cap hermetically seal the porous electrically conductive material from environmental factors.
12. A battery, as in claim 11 , further comprising a thicker conductive layer between the seed layer and the cap.
13. A battery, as in claim 11 , where the cap comprises any of following materials: an electroplated metal layer, a solder, a solder ball, a solder connection deposited by Injection Molded Solder (IMS), a solder connection deposited by stencil printing using a mold, Sn, Sn—Cu, Sn—Ag, SnCuAg, In, SnIn SnBi, and SnBiIn.
14. A battery, as in claim 11 , where the substrate comprises one or more of the following materials: mica, silicon, silicon with Al 2 O 3 , SiN, sapphire coating, oxide coating, nitride coating, Yttrium Stabilized Zirconia (YSZ), Zirconia, metal layer, dielectric insulator, organic material, rubber, multiple thin metal layers, dielectric barrier layers, alumina, ceramic, and a polymer material.
15. A battery, as in claim 11 , where the porous electrically conductive material comprises one or more of the following: silver (Ag,) a metal polymer, a metal ceramic, and a conductive composite.
16. A battery, as in claim 11 , that is one of the batteries in an array of batteries.
17. A battery, as in claim 11 , where the environmental factors are sealed from the cathode, anode, and electrolyte while the battery undergoes conditions of at least 80% relative humidity at 65° C. for 187 hours.