Method and structure for fabricating sensors with a sacrificial gel dome

• US 20040118214A1
• Filed: 12/23/2002
• Published: 06/24/2004
• Est. Priority Date: 12/23/2002
• Status: Active Grant

• Current Assignee: North Star Innovations Inc. (Wi-LAN Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: McDonald, William G., Hooper, Stephen Ryan
• Granted Patent: US 7,014,888 B2
• Time in Patent Office: Days
• US Class Current: 73/756
• CPC Class Codes: G01L 19/0069 from the sensor to its support
• CPC Class Codes: G01L 19/141 Monolithic housings, e.g. molded or one-piece housings
• CPC Class Codes: G01L 19/147 Details about the mounting of the sensor to support or covering means
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/49171 Fan-out arrangements
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding

Abstract

A method and structure that protects interior electrical components of a pressure sensor (4) from corrosive particles using a sacrificial gel dome (30) to form a vent (34) in a protective gel (32) that covers electrical components that can be corroded such as wires (16), bond pads (18), and electrical leads (14). Sacrificial gel dome (30) is dispensed over a diaphragm (28) of pressure sensor (4) to form vent (34) enabling diaphragm (28) to sense pressure variations without the influence of protective gel (32). Sacrificial gel dome (30) is removed through a water rinsing process (42) to expose vent (34).

Claims

1. A packaged pressure sensor, comprising:

a housing having an interior chamber;

a pressure sensor having a diaphragm placed in said interior chamber;

an electrical lead protruding through said housing;

a wire coupling said electrical lead to said pressure sensor; and

a protective gel covering said electrical lead and said wire surrounding said diaphragm, thereby defining a vent over said diaphragm.

2. The packaged pressure sensor of claim 1, wherein a portion of said protective gel extends partially over said diaphragm.

3. The packaged pressure sensor of claim 1, wherein said protective gel is silicon based.

4. The packaged pressure sensor of claim 1, wherein said vent is formed through the use of a sacrificial structure.

5. The packaged pressure sensor of claim 4, wherein said sacrificial structure is soluble.

6. The packaged pressure sensor of claim 4, wherein said protective gel fills said interior chamber to a level below a top portion of said sacrificial structure.

13. The packaged pressure sensor of claim 1, further comprising a cap having a membrane formed therein, said cap attached to said housing such that it covers said interior chamber.

7. A packaged pressure sensor, comprising:

a pressure sensor to detect an environmental pressure;

a housing to protect said pressure sensor from a corrosive environment surrounding said housing, said housing having an interior chamber in which said pressure sensor is disposed;

electrical communication means to enable said pressure sensing means to communicate a pressure reading to an external circuit;

a protective gel to protect said electrical communication means from said corrosive environment without covering a pressure sensing diaphragm coupled to said pressure sensor, thereby defining a vent over said pressure sensing diaphragm.

8. The packaged pressure sensor of claim 7, further comprising sacrificial means to form said protective gel means to define said vent.

9. The packaged pressure sensor of claim 8, wherein said protective gel fills said interior chamber to a level below a top portion of said sacrificial means.

10. The packaged pressure sensor of claim 8, wherein said sacrificial means is soluble.

12. The packaged pressure sensor of claim 7, wherein said protective gel is silicon based.

14. A method of fabricating corrosion protection for a sensor, comprising:

dispensing a viscous mask over a diaphragm of a pressure sensor contained within a housing;

hardening said viscous mask;

dispensing a protective gel into said housing over an electrical lead and a wire coupled to said pressure sensor;

hardening said protective gel; and

removing said viscous mask.

15. The method of claim 14, wherein said hardening of said viscous mask is performed with an ultra-violet light.

16. The method of claim 14, wherein said hardening of said protective gel is performed with a thermal process.

17. The method of claim 14, further comprising rinsing said viscous mask from said pressure sensor.

18. The method of claim 17, wherein the removing of said viscous mask further includes dissolving said viscous mask with hot deionized water.

19. The method of claim 14, further comprising depositing said protective gel at a level lower than said viscous mask.

20. The method of claim 14, further comprising aligning a needle over said diaphragm to dispense said highly viscous mask as a droplet.

21. The method of claim 14, wherein dispensing said viscous mask over said diaphragm is performed without the aid of a structure to contain said viscous mask over said diaphragm.