Method and structure for fabricating sensors with a sacrificial gel dome

• US 7,014,888 B2
• Filed: 12/23/2002
• Issued: 03/21/2006
• Est. Priority Date: 12/23/2002
• Status: Expired due to Fees

• Current Assignee: North Star Innovations Inc. (Wi-LAN Inc.)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: McDonald, William G., Hooper, Stephen Ryan
• Primary Examiner(s): PARKER, FREDERICK JOHN
• Application Number:
  US10/326,675
• Publication Number:
  US 20040118214A1
• Time in Patent Office: 1,184 Days
• Field of Search: 427154-156, 427/259, 427/264, 427/265, 427/273, 427/282, 427/336, 427/557, 427/558, 427/387, 737/56, 361517-520, 361534-539
• US Class Current: 427/558
• 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 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 after said dispensing;

after said hardening said viscous mask, dispensing a protective gel into said housing over an electrical lead and a wire coupled to said pressure sensor, wherein said dispersing said protective gel includes dispersing said protective gel to leave a top of said viscous mask uncovered;

hardening said protective gel; and

removing said viscous mask, wherein said removing said viscous mask includes removing said viscous mask with a fluid.

2. The method of claim 1, wherein said hardening of said viscous mask is performed with an ultra-violet light.

3. The method of claim 1, wherein said hardening of said protective gel is performed with a thermal process.

4. The method of claim 1, wherein said removing of said viscous mask further comprises rinsing said viscous mask from said pressure sensor.

5. The method of claim 4, wherein the removing of said viscous mask further includes dissolving said viscous mask with hot deionized water.

6. The method of claim 1, wherein said dispensing a protective gel further comprising depositing said protective gel to a level below a top of said viscous mask.

7. The method of claim 1, further comprising aligning a needle over said diaphragm to dispense said viscous mask as a droplet.

8. The method of claim 1, wherein dispensing said viscous mask over said diaphragm is performed without the aid of a structure to contain said viscous mask over said diaphragm.

9. The method of claim 4 wherein said rinsing said viscous mask from said pressure sensor further includes dissolving said viscous mask wherein said dissolving said viscous mask leaves little or no solid residue of a material of said viscous mask.

10. The method of claim 1 wherein said removing said viscous mask forms a vent through said protective gel to said diaphragm.

11. The method of claim 1 wherein said viscous mask is of a material that is water soluble.

12. The method of claim 1 wherein said dispensing a protective gel into said housing further includes dispensing a protective gel into said housing over a bond pad.

13. The method of claim 1 wherein said removing said viscous mask is performed after said hardening said viscous mask.

14. The method of claim 1 wherein said removing said viscous mask is performed after said hardening said protective gel.

15. The method of claim 1 further comprising attaching a cap with a porous membrane to said housing.

16. 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 after said dispensing said viscous mask;

after said hardening said viscous mask, dispensing a protective gel into said housing;

hardening said protective gel; and

after said hardening said viscous mask, removing said viscous mask with a fluid to form a vent through said protective gel to said diaphragm.

17. 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 after said dispensing said viscous mask;

after said hardening said viscous mask, dispensing a protective gel into said housing to a level below a top of said viscous mask over an electrical lead and a wire coupled to said pressure sensor;

hardening said protective gel; and

removing said viscous mask with a fluid.