SYSTEM AND METHOD OF TESTING HUMIDITY IN A SEALED MEMS DEVICE

• US 20080115569A1
• Filed: 01/28/2008
• Published: 05/22/2008
• Est. Priority Date: 09/27/2004
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Palmateer, Lauren, Cummings, William, Kothari, Manish, Gally, Brian
• Granted Patent: US 7,623,752 B2
• Time in Patent Office: Days
• US Class Current: 73/73
• CPC Class Codes: B81C 99/0045 End test of the packaged device
• CPC Class Codes: G01M 3/002 by using thermal means
• CPC Class Codes: G01M 3/02 by using fluid or vacuum
• CPC Class Codes: G01M 3/186 for containers, e.g. radiators
• CPC Class Codes: G01M 3/229 removably mounted in a test cell
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

One embodiment provides a method of testing humidity, comprising: i) determining a property of a device which encloses a plurality of interferometric modulators and ii) determining a relative humidity value or a degree of the relative humidity inside the device based at least in part upon the determined property, wherein the determined property comprises at least one of i) the thickness and width of a seal of the device and ii) adhesive permeability of a component of the device. In one embodiment, the determined property further comprises at least one of the following: i) temperature-humidity combination inside the device, ii) a desiccant capacity inside the device and iii) a device size.

Claims

1. A method of testing humidity, comprising:

determining a property of a device which encloses a plurality of interferometric modulators; and

determining a relative humidity value or a degree of the relative humidity inside the device based at least in part upon the determined property, wherein the determined property comprises at least one of i) the thickness and width of a seal of the device and ii) adhesive permeability of a component of the device.

2. The method of claim 1, further comprising exposing the device to a humid environment before determining the property.

3. The method of claim 2, wherein the humid environment includes a humidity chamber.

4. The method of claim 1, wherein the determined property further comprises at least one of the following:

i) temperature-humidity combination inside the device, ii) a desiccant capacity inside the device and iii) a device size.

5. The method of claim 1, wherein only the relative humidity value is determined based upon the determined property.

6. A system for testing humidity, comprising:

first means for determining a property of a device which encloses a plurality of interferometric modulators; and

second means for determining a relative humidity value or a degree of the relative humidity inside the device based at least in part upon the determined property, wherein the determined property comprises at least one of i) the thickness and width of a seal of the device and ii) adhesive permeability of a component of the device.

7. The system of claim 6, wherein the determined property further comprises at least one of the following:

i) temperature-humidity combination inside the device, ii) a desiccant capacity inside the device and iii) a device size.

8. The system of claim 6, wherein the second means is configured to determine only the relative humidity value based upon the determined property.

9. A method of testing humidity, comprising:

providing a device which encloses i) a plurality of interferometric modulators and ii) a desiccant, wherein the desiccant is configured to change its color based on an amount of water vapor absorbed therein;

determining a degree of a color change of the desiccant; and

determining a relative humidity value inside the device based at least in part upon the determined degree of the color change.

10. The method of claim 9, wherein the device comprises a backplate which includes at least a transparent portion, and wherein determining the degree of the color change is performed via the transparent portion of the backplate.

11. The method of claim 9, wherein the device comprises a transparent backplate, and wherein determining the degree of the color change is performed via the transparent backplate.

12. The method of claim 9, wherein determining the degree of a color change of the desiccant comprises:

exposing the device to a humid environment;

determining a first color of the desiccant before exposing the device to a humid environment;

determining a second color of the desiccant after exposing the device to the humid environment;

comparing the first and second colors; and

determining the degree of a color change of the desiccant based on the color comparison.

13. The method of claim 9, wherein the relative humidity value inside the device is determined considering at least one of the following parameters:

i) temperature-humidity combination inside the device, ii) the thickness and width of a seal of the device, iii) adhesive permeability of a component of the device, iv) a desiccant capacity inside the device and v) a device size.

14. A method of manufacturing a microelectromechanical systems (MEMS) device, the method comprising:

providing a substrate;

forming a plurality of interferometric modulators on the substrate;

providing a desiccant configured to change its color based on an amount of water vapor absorbed therein;

providing a backplate; and

joining the substrate and the backplate so as to form a device which encloses the plurality of interferometric modulators and the desiccant,

wherein the backplate includes at least one transparent portion through which the color change of the desiccant can be viewed from the outside of the device, and wherein a relative humidity value inside the MEMS device is determined based at least in part upon the determined degree of the color change.

15. The method of claim 14, wherein the relative humidity value inside the device is determined considering at least one of the following parameters:

i) temperature-humidity combination inside the device, ii) the thickness and width of a seal of the device, iii) adhesive permeability of a component of the device, iv) a desiccant capacity inside the device and v) a device size.

16. A microelectromechanical systems (MEMS) device, comprising:

a substrate;

a plurality of interferometric modulators formed on the substrate;

a desiccant configured to change its color based on an amount of water vapor absorbed

therein; and

a backplate,

wherein the substrate and backplate are joined to each other so as to form a device which encloses the plurality of interferometric modulators and the desiccant,

wherein the backplate includes at least one transparent portion through which the color change of the desiccant can be viewed from the outside of the device, and wherein a relative humidity value inside the MEMS device is determined based at least in part upon the determined degree of the color change.

17. The device of claim 16, wherein the backplate is formed of a transparent material.

18. The device of claim 16, wherein the relative humidity value inside the device is determined considering at least one of the following parameters:

i) temperature-humidity combination inside the device, ii) the thickness and width of a seal of the device, iii) adhesive permeability of a component of the device, iv) a desiccant capacity inside the device and v) a device size.