WATER PROOFING AND WATER DETECTION SCHEMES FOR MEMS-BASED ENVIRONMENTAL SENSING DEVICES

• US 20190100428A1
• Filed: 09/28/2018
• Published: 04/04/2019
• Est. Priority Date: 09/29/2017
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: VUMMIDI MURALI, Krishna Prasad, LEI, Kuolung, YEH, Richard, MA, Yun X.
• Granted Patent: US 10,640,367 B2
• Time in Patent Office: Days
• CPC Class Codes: B81B 2201/0214 Biosensors; Chemical sensors
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2201/0278 Temperature sensors
• CPC Class Codes: B81B 2203/0127 Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
• CPC Class Codes: B81B 2203/04 Electrodes
• CPC Class Codes: B81B 2207/012 the micromechanical device and the control or processing electronics being separate parts in the same package
• CPC Class Codes: B81B 2207/096 through the substrate
• CPC Class Codes: B81B 7/0029 Protection against environmental influences not provided for in groups B81B7/0012 - B81B7/0025
• CPC Class Codes: B81B 7/0058 for protecting against damages due to external chemical or mechanical influences, e.g. shocks or vibrations
• CPC Class Codes: B81B 7/0077 Other packages not provided for in groups B81B7/0035 - B81B7/0074
• CPC Class Codes: B81C 1/0023 Packaging together an electronic processing unit die and a micromechanical structure die MEMS packages B81B7/0032; MEMS packaging processes B81C1/00261
• CPC Class Codes: B81C 2203/0136 Growing or depositing of a covering layer
• CPC Class Codes: B81C 2203/0792 Forming interconnections between the electronic processing unit and the micromechanical structure

Abstract

A waterproofed environmental sensing device with water detection provisions includes an environmental sensor to sense one or more environmental properties. The device further includes an electronic integrated circuit implemented on a substrate and coupled to the environmental sensor via a wire bonding. An air-permeable cap structure is formed over the environmental sensor, and a protective layer is formed over the wire bonding to protect the wire bonding against damage.

Claims

1. A device comprising:

an environmental sensor configured to sense one or more environmental properties;

an electronic integrated circuit implemented on a substrate and coupled to the environmental sensor via a wire bonding;

an air-permeable cap structure formed over the environmental sensor; and

a protective layer formed over the wire bonding to protect the wire bonding against a potential damage.

2. The device of claim 1, wherein the environmental sensor comprises a miniature environmental sensor, and wherein the miniature environmental sensor is configured to sense a gas or an environmental parameter including a pressure, a temperature or a humidity.

3. The device of claim 1, wherein the air-permeable cap structure is configured to protect a surface of the environmental sensor from environmental aggressors including water and oil.

4. The device of claim 3, wherein the air-permeable cap structure is made of a suitable material including silicon, and wherein the air-permeable cap structure includes a coated hydrophobic layer.

5. The device of claim 1, wherein the environmental sensor is formed in an electro-mechanical system (MEMS) structure and wire bonded to the electronic integrated circuit through an interposer including through-silicon vias (TSVs).

6. The device of claim 5, wherein the MEMS structure and the interposer are coupled to the electronic integrated circuit via flip-chip bonding, and wherein the electronic integrated circuit includes one or more capacitive elements configured to detect presence of at least water and oil.

7. The device of claim 5, further comprising resistive routings configured to provide heat for calibrating (temperature coefficient offset) TCO and for ejecting water from a surface of the air-permeable cap structure, wherein the resistive routings are implemented in the MEMS structure.

8. The device of claim 5, wherein strain isolation provisions are implemented in at least one of the electronic integrated circuit or the MEMS structure.

9. The device of claim 1, further comprising interdigitated electrodes implementing capacitors capable of detecting environmental aggressors including water, and wherein the interdigitated electrodes are realized using a top metal layer and passivation.

10. A device comprising:

an environmental sensor embedded in an electro-mechanical system (MEMS) structure;

an electronic integrated circuit (IC); and

one or more passive elements,

wherein;

the device is partially enclosed in an enclosure,

the enclosure is at least partially filled with a sensor gel, and

the one or more passive elements are at least partially exposed above the sensor gel.

11. The device of claim 10, wherein the one or more passive elements comprise capacitive elements and are coupled to the electronic IC, and wherein the passive elements are configured to detect presence of at least water and oil above the gel sensor.

12. The device of claim 11, wherein the electronic IC includes a strain isolation provision, and wherein the electronic IC includes resistive routings configured to allow TCO calibration.

13. The device of claim 11, further comprising a membrane configured to provide strain isolation, wherein the membrane is made of a material including silicone rubber.

14. The device of claim 13, wherein the environmental sensor is coupled to the electronic IC via a wire bonding, and wherein the membrane is formed between the MEMS structure and the electronic IC.

15. The device of claim 13, further comprising a land grid array (LGA) layer, wherein the MEMS structure is wire bonded to the LGA layer, wherein least one of the LGA layer or the electronic integrated circuit includes resistive-routing for TCO calibration.

16. A device comprising:

a land grid array (LGA) layer

an environmental sensor embedded in an electro-mechanical system (MEMS) structure and coupled to the LGA layer via a wire bonding; and

an integrated circuit (IC) implemented on the LGA layer,

wherein;

the device is partially enclosed in an enclosure,

the enclosure is at least partially filled with a sensor gel, and

the integrated circuit (IC) is at least partially exposed above the sensor gel.

17. The device of claim 16, wherein the electronic IC is thicker than the MEMS structure, wherein one or more capacitive elements are implemented on a surface of the electronic IC that appears outside the gel sensor.

18. The device of claim 17, and wherein one or more heating elements are implemented in at least one of the electronic IC or the LGA layer.

19. The device of claim 18, wherein the one or more heating elements are controlled based on a feedback from the one or more capacitive elements.

20. The device of claim 19, wherein a level of an exposed surface of the sensor gel is substantially flush to a housing structure of the device, wherein the LGA layer is formed over a substrate, wherein the substrate comprises a flex substrate, wherein the sensor gel covers at least one of the one or more heating elements.