Sensor substrate and method of fabricating same

• US 20030049166A1
• Filed: 01/02/2002
• Published: 03/13/2003
• Est. Priority Date: 09/07/2001
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Shah, Rajiv, Pendo, Shaun, Chernoff, Edward
• Granted Patent: US 7,323,142 B2
• Time in Patent Office: Days
• US Class Current: 422/56
• CPC Class Codes: A61B 5/0006 ECG or EEG signals
• CPC Class Codes: H05K 1/0306 Inorganic insulating substrates, e.g. ceramic, glass
• CPC Class Codes: H05K 2201/0175 Inorganic, non-metallic layer, e.g. resist or dielectric for printed capacitor
• CPC Class Codes: H05K 2201/0179 Thin film deposited insulating layer, e.g. inorganic layer for printed capacitor
• CPC Class Codes: H05K 2201/0317 Thin film conductor layer; Thin film passive component
• CPC Class Codes: H05K 2201/09472 Recessed pad for surface mounting recess in pad H05K2201/09745; Recessed electrode of component
• CPC Class Codes: H05K 2203/082 Suction, e.g. for holding solder balls or components
• CPC Class Codes: H05K 2203/085 Using vacuum or low pressure
• CPC Class Codes: H05K 2203/1147 Sealing or impregnating, e.g. of pores
• CPC Class Codes: H05K 2203/1476 Same or similar kind of process performed in phases, e.g. coarse patterning followed by fine patterning
• CPC Class Codes: H05K 2203/1572 Processing both sides of a PCB by the same process; Providing a similar arrangement of components on both sides; Making interlayer connections from two sides
• CPC Class Codes: H05K 2203/308 Sacrificial means, e.g. for temporarily filling a space for making a via or a cavity or for making rigid-flexible PCBs
• CPC Class Codes: H05K 3/28 Applying non-metallic protective coatings H05K3/0091 takes precedence; methods for intermediate insulating layers for build-up multilayer circuits H05K3/4673
• CPC Class Codes: H05K 3/4061 for via connections in inorganic insulating substrates

Abstract

A substrate with hermetically sealed vias extending from one side of the substrate to another and a method for fabricating same. The vias may be filled with a conductive material such as, for example, a fritless ink. The conductive path formed by the conductive material aids in sealing one side of the substrate from another. One side of the substrate may include a sensing element and another side of the substrate may include sensing electronics.

Claims

1. A sensing apparatus comprising:

a substrate having a first side for a sensing element and a second side for electronics; and

a via making electrical contact from the first side of the substrate to the second side of the substrate,

wherein the via is hermetically sealed from the first side of the substrate to the second side of the substrate.

2. A sensing apparatus according to claim 1, wherein the via is filled with a conductive material.

3. A sensing apparatus according to claim 2, wherein the conductive material is a fritless ink.

4. A sensing apparatus according to claim 3, wherein the fritless ink is a gold paste.

5. A sensing apparatus according to claim 3, wherein the fritless ink is a platinum paste.

6. A sensing apparatus according to claim 1, wherein the substrate is ceramic.

7. A sensing apparatus according to claim 1, wherein the substrate is substantially 92%-96% alumina.

8. A sensing apparatus according to claim 1, wherein the second side is covered with a lid.

9. A sensing apparatus according to claim 8, wherein the lid is made of gold.

10. A sensing apparatus according to claim 1, further comprising a cap covering the via.

11. A sensing apparatus according to claim 10, wherein the cap is made from alumina.

12. A sensing apparatus according to claim 11, wherein the alumina cap is deposited using an ion beam assist deposition process.

13. A sensing apparatus according to claim 1, wherein the via comprises a plurality of vias.

14. A sensing apparatus according to claim 1, wherein the substrate is annealed.

15. A method of forming an hermetically sealed substrate comprising:

obtaining a substrate material;

forming a via from a first side of the substrate to a second side of the substrate; and

filling the via with a conductive material such that an hermetic seal forms between the first side of the substrate and the second side of the substrate.

16. A method according to claim 15, wherein forming a via comprises laser drilling the via.

17. The method according to claim 16, wherein forming the via further comprises annealing the substrate.

18. The method according to claim 15, wherein filling the via comprises

placing a screen on a surface of the substrate;

pushing the conductive material through the screen such that the conductive material proceeds into the via; and

pulling a vacuum on a side of the substrate opposite the side on which the conductive material has been pushed into the via such that the conductive material coats a wall of the via.

19. The method according to claim 18, wherein filling the via further comprises filling a meniscus that forms within the via.

20. The method according to claim 19, wherein filling a meniscus comprises

putting the substrate into a vacuum;

printing a conductive material into the meniscus; and

venting the substrate to atmosphere;

21. The method according to claim 20, wherein filling a meniscus further comprises firing the substrate.

22. The method according to claim 15, further comprising depositing a pillar on top of the via.

23. The method according to claim 22, wherein depositing a pillar comprises;

affixing a mask to the substrate;

depositing a metal on top of the mask;

removing the mask after depositing the metal; and

coating the substrate with a ceramic.

24. The method according to claim 23, further comprising dissolving the metal after the substrate has been coated with the ceramic.

25. The method according to claim 23, wherein the ceramic coating is shorter than the pillar.

26. The method according to claim 15, further comprising covering the via with a cap.

27. The method according to claim 26, wherein covering the via is done using an ion beam assist deposition process.

28. The method according to claim 18, wherein a stencil is used in place of the screen.

29. A sensing apparatus comprising:

a substrate having a first area for a sensing element and a second area for electronics; and

a via making electrical contact from the first area of the substrate to the second area of the substrate,

wherein the via is hermetically sealed from the first area of the substrate to the second area of the substrate.

30. A sensing apparatus according to claim 29, wherein the via is filled with a conductive material.