Opaque color stack for electronic device

1. An electronic device, comprising:

a capacitive sensor;

a transparent substrate; and

a black color stack disposed on the transparent substrate, wherein the black color stack absorbs all incident light and completely overlaps the capacitive sensor, wherein capacitive coupling occurs through the black color stack when the capacitive sensor receives touch input, and wherein the black color stack comprises:

a pigment stack comprising:

a first dielectric layer comprising a first material;

a second dielectric layer comprising a second material different from the first material; and

a first light absorption layer comprising an absorbing material positioned between the first and second dielectric layers, wherein:

the first dielectric layer has a first refractive index; and

the second dielectric layer has a second refractive index different from the first refractive index; and

a plurality of second light absorption layers interleaved with a plurality of third dielectric layers; wherein:

the second light absorption layers comprise the absorbing material; and

the third dielectric layers comprise the first material.

2. The electronic device of claim 1 , wherein the first dielectric layer and the second dielectric layer comprise a material selected from a group consisting of silicon oxide, silicon nitride, and niobium oxide.

3. The electronic device of claim 1 , wherein the black color stack has an electrical resistivity of at least 10 14 Ωcm or greater.

4. The electronic device of claim 1 , wherein the black color stack has an optical density of at least 3 or greater.

5. The electronic device of claim 1 , wherein each of the first, second, and third dielectric layers has a dielectric constant lower than a threshold and wherein the threshold of the dielectric constant is 50.

6. The electronic device of claim 1 wherein each of the first and second light absorption layers comprises a material selected from a group consisting of tin, copper oxide, and zinc oxide.

7. The electronic device of claim 1 , wherein:

the first light absorption layer is formed from tin;

the first light absorption layer has a thickness equal to or less than 100 nm such that the first light absorption layer is non-conductive.

8. The electronic device of claim 7 , wherein the tin layer has a thickness of about 5 nm.

9. The electronic device of claim 1 , wherein each of the first, second, and third dielectric layers has a thickness ranging from 10 nm to 100 nm.

10. The electronic device of claim 1 , wherein the transparent substrate comprises sapphire or glass.

11. The electronic device of claim 1 , wherein the black color stack has a thickness ranging from 1 μm to 2 μm.

12. The electronic device of claim 1 , wherein the sensor is positioned adjacent the black color stack such that the sensor is concealed from view, by the black color stack, from a top of the transparent substrate.

13. A method for forming a black color stack over a capacitive sensor, wherein the black color stack absorbs all incident light, the method comprising:

depositing a pigment stack on a transparent substrate, comprising:

depositing, on the substrate, a first dielectric layer comprising a first material having a first refractive index;

depositing, on the first dielectric layer, a first light absorption layer comprising an absorbing material;

depositing, on the first light absorption layer, a second dielectric layer comprising a second material different from the first material and having a second refractive index different from the first refractive index; and

depositing a non-conductive light-absorbing stack on the pigment stack, comprising interleaving a plurality of second light absorption layers with a plurality of third dielectric layers, wherein the second light absorption layers comprise the absorbing material and the third dielectric layers comprise the first material; and

positioning the capacitive sensor adjacent to the light-absorbing stack, wherein capacitive coupling occurs through the black color stack when the capacitive sensor receives touch input and wherein the black color stack completely overlaps the capacitive sensor.

14. The method of claim 13 , wherein the non-conductive light-absorbing stack has a thickness ranging from 1 μm to 2 μm.

15. The method of claim 13 , wherein depositing the pigment stack on the transparent substrate includes a process selected from a group consisting of physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), and ion beam assisted deposition (BAD).

16. The method of claim 13 , wherein the first dielectric layer and the second dielectric layer comprise a material selected from a group consisting of silicon oxide, silicon nitride, and niobium oxide.

17. The method of claim 13 , wherein the first light absorption layer comprises a material selected from a group consisting of tin, copper oxide, and zinc oxide.

18. The method of claim 13 , wherein:

the first light absorption layer is formed from tin;

the first light absorption layer has a thickness equal to or less than 100 nm such that the first light absorption layer is non-conductive.

19. The method of claim 13 , wherein the non-conductive light-absorbing stack comprises a stack of eighteen tin layers interleaved with nineteen silicon nitride layers.

20. The method of claim 13 , wherein the pigment stack has a thickness equal to or less than 100 nm.

21. The method of claim 13 , wherein the transparent substrate comprises sapphire or glass.

22. The method of claim 13 , wherein the black color stack has an optical density of at least 3 or greater.

23. A button assembly, comprising:

a transparent substrate;

a non-conductive color stack disposed on the transparent substrate and having at least 20 layers occupying a combined thickness less than about 2 μm, wherein the non-conductive color stack absorbs all incident light, the non-conductive color stack comprising:

a pigment stack comprising:

a first dielectric layer;

a second dielectric layer having a refractive index different from the first dielectric layer; and

a first light absorbing layer positioned between the first and second dielectric layers; and

a light absorbing stack comprising a plurality of third dielectric layers interleaved with a plurality of second light absorbing layer; and

a capacitive sensor below the non-conductive color stack, wherein capacitive coupling occurs through the non-conductive color stack when the capacitive sensor receives touch input and wherein the non-conductive color stack completely overlaps the capacitive sensor.

24. The button assembly of claim 23 , wherein the first light absorbing layer and the plurality of second light absorbing layers comprise a same material.

25. The button assembly of claim 23 , wherein each of the second light absorbing layers is about 5 nm thick.

26. The button assembly of claim 23 , wherein the plurality of third dielectric layers comprise a material different from the second dielectric layer.

27. The button assembly of claim 23 , wherein the plurality of third dielectric layers interleaved with the plurality of second light absorbing layers comprises:

nineteen third dielectric layers; and

eighteen second light absorbing layers.

28. The button assembly of claim 27 , wherein:

the first dielectric layer and the plurality of third dielectric layers comprise silicon nitride;

the second dielectric layer comprises silicon oxide; and

the first light absorbing layer and the plurality of second light absorbing layers comprise tin.