Sensor substrate and method of fabricating same

• US 8,821,793 B2
• Filed: 10/25/2007
• Issued: 09/02/2014
• Est. Priority Date: 09/07/2001
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Pendo, Shaun, Shah, Rajiv, Chernoff, Edward
• Primary Examiner(s): Hyun, Paul
• Application Number:
  US11/924,402
• Publication Number:
  US 20080050281A1
• Time in Patent Office: 2,504 Days
• Field of Search: 422/82.01
• US Class Current: 422/82.01
• 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 composed of alumina and having a first side for a sensing element that is configured to be exposed to a biological material and a second side for electronics;

a via comprising a linear hollow path formed from the first side of the substrate to the second side of the substrate and filled with an electrically conductive material for electrically coupling the sensing element on the first side of the substrate to the electronics on the second side of the substrate;

a conductive layer having a portion over the via on the first side of the substrate and in electrical communication with the electrically conductive material in the via; and

a cap placed on the first side of the substrate over and in contact with the portion of the conductive layer, the cap sealing the via against exposure to the biological material;

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

wherein the second side is covered with a lid and wherein the lid is made of gold.

2. A sensing apparatus according to claim 1, wherein the electrically conductive material is a fritless ink.

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

4. A sensing apparatus according to claim 2, wherein the fritless ink is a platinum paste.

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

6. A sensing apparatus according to claim 1, wherein the cap is substantially of the same size as an end portion of the via.

7. A sensing apparatus according to claim 1, wherein the cap is made from alumina.

8. A sensing apparatus according to claim 7, wherein the alumina cap is deposited using an ion beam assist deposition process.

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

and the cap further comprises a plurality of caps; and

wherein each via is covered by a respective portion of the conductive layer and at least one cap.

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

11. A sensing apparatus according to claim 1, wherein the linear hollow path defines a boundary between the electrically conductive material and the substrate.

12. A sensing apparatus according to claim 1, wherein the cap seals the portion of the substrate with the via leaving substantially all other portions of the substrate exposed.

13. A sensing apparatus according to claim 1,

further comprising a sensing element disposed on the first side of the substrate;

wherein the cap is configured to prevent the biological material from being in contact with the via while the sensing element on the first side of the substrate is exposed to the biological material.

14. A sensing apparatus according to claim 1,

further comprising a sensing element disposed on the first side of the substrate;

wherein the portion of the conductive layer is between the cap and the substrate.

15. A sensing apparatus according to claim 14, wherein the conductive layer is electrically coupled to one or more of a glucose sensor and oxygen sensor.

16. A sensing apparatus according to claim 1, further comprising a sensing element disposed on the first side of the substrate;

wherein the sensing element is a biological sensor.

17. A sensing apparatus according to claim 1, wherein the portion of the conductive layer is located between an end portion of the via and the cap.

18. A sensing apparatus according to claim 1, wherein the conductive layer is deposited onto an end portion of the via, and wherein the cap is deposited onto the portion of the conductive layer.