Sensor package for harsh environments

• US 20030107467A1
• Filed: 04/22/2002
• Published: 06/12/2003
• Est. Priority Date: 12/07/1998
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Bonne, Ulrich, Satren, Ernest
• Granted Patent: US 6,911,894 B2
• Time in Patent Office: Days
• US Class Current: 338/25
• CPC Class Codes: G01F 1/6842 with means for influencing the fluid flow
• CPC Class Codes: G01F 1/6845 Micromachined devices
• CPC Class Codes: G01F 1/6847 where sensing or heating elements are not disturbing the fluid flow, e.g. elements mounted outside the flow duct
• CPC Class Codes: G01F 5/00 Measuring a proportion of the volume flow
• CPC Class Codes: G01N 1/2247 Sampling from a flowing stream of gas
• CPC Class Codes: G01N 2001/2285 Details of probe structures
• CPC Class Codes: G01N 25/18 by investigating thermal conductivity by calorimetry G01N25/20; by measuring change of resistance of an electrically-heated body G01N27/18
• CPC Class Codes: G01N 25/488 Details
• CPC Class Codes: G01N 33/0014 by eliminating a gas by a chemical reaction G01N33/0013; a chemical reaction taking place or a gas being eliminated in one or more analysing channels G01N33/0024

Abstract

A sensor can be configured to generally include a flow channel block having a flow channel formed therein, and a sensor chip for sensing fluid flow, wherein a fluid in the flow channel surrounds the sensor chip. Alternatively, the sensor chip can be fastened at one side to a substrate and on another side of the substrate to a core tube inserted into the flow channel. This core tube provides electrical insulation and corrosion protection to the sensor chip, reduces flow noise, (and by the non-intrusive nature of the measurement) essentially eliminates the risk of fluid leakage, and maintains the fluid super-clean and contamination-free while improving structural integrity for the thermal measurements derived from the sensor chip. The use of such a core tube configuration also can protect the sensor from corrosion, radioactive or bacterial contamination, overheating, or freeze-ups. Such a core tube configuration also enables the core tube to be detachable and disposable, without requiring the replacement of the more costly sensor chip with its electronics and calibration.

Claims

1. A sensor for detecting liquid flow in harsh environments, said sensor comprising:

a flow channel block having a flow channel formed therein;

a sensor chip for sensing fluid flow, wherein said sensor chip is located proximate to said flow channel of said flow channel block;

a substrate in communication with said sensor chip and at least one electrical contact bonded to it by at least one bonding element; and

a core tube between said flow channel block and said flow channel thereby permitting said sensor to be utilized to detect liquid flow in harsh environments.

2. The sensor of claim 1 wherein said sensor chip is exposed to a fluid following a molding of said flow channel via said core tube and removal of said core tube thereof.

3. The sensor of claim 1 wherein said sensor chip is exposed to a fluid when said core tube is left in place between said flow channel block and said flow channel.

4. The sensor of claim 1 wherein said at least one bonding element comprises at least one front wire bond (FWB).

5. The sensor of claim 1 wherein said at least one bonding element comprises at least one through-the-wafer (TTW) contact.

6. The sensor of claim 1 wherein said core tube comprises a polymeric material.

7. The sensor of claim 1 wherein said core tube comprises a fluoropolymer.

8. The sensor of claim 7 wherein said fluoropolymer comprises Aclar.

9. The sensor of claim 7 wherein said fluorpolymer comprises Teflon.

10. The sensor of claim 1 wherein said core tube comprises glass.

11. The sensor of claim 1 wherein said core tube comprises quartz.

12. The sensor of claim 1 wherein said core tube comprises sapphire.

13. The sensor of claim 1 wherein said core tube comprises a metal.

14. The sensor of claim 1 wherein said core tube includes a wall having a wall thickness that prevents a surface of said sensor chip from direct contact with a fluid flowing through said core tube by a distance corresponding to said wall thickness.

15. The sensor of claim 1 wherein said sensor chip is covered by a film that combines a predefined dielectric strength and chemical inertness with hydrophobic properties.

16. The sensor of claim 15 wherein said protective film comprises a fluoropolymer.

17. The sensor of claim 15 wherein said protective film comprises a laminate material, including a metal thereof for prevention of fluid diffusion.

18. The sensor of claim 15 wherein said film is enlarged to comprise a potting compound of said bonding elements, whereby said potting compound is shaped by said core tube.

19. The sensor of claim 18 wherein said film comprises an epoxy.

20. The sensor of claim 1 wherein said core tube comprises a constriction in a cross section of said core tube at said sensor chip.

21. The sensor of claim 1 wherein said core tube and said substrate are replaceable by a flat film wrapped about a header and sealed by an O-ring to provide thermal conductivity measurement sensor capabilities thereof, in a zero forced-convection environment.

22. The sensor of claim 1 wherein said flow channel block comprises a flow tube.

23. The sensor of claim 22 wherein said flow tube comprises a disposable flow tube.

24. The sensor of claim 1 further comprising a heat sink mechanism for heat sinking a reference resistance associated with said sensor so that an associated sensor heater does not increase in temperature beyond an intended set point.

25. The sensor of claim 1 wherein said substrate is glass.

26. The sensor of claim 1 wherein said substrate is silicon.

27. A sensor for detecting liquid flow in harsh environments, said sensor comprising:

a thermal microsensor for sensing a fluid parameter based on heat transfer and thermal conductivity thereof;

at least one sensing element associated within said thermal microsensor; and

a thin film applied to said at least one sensing element, wherein said thin film is applied thinly.

28. The sensor of claim 27 wherein a thickness of said thin film applied to said at least one sensing element is in an inclusive range of approximately 0.001-in to 0.010-in.

29. The sensor of claim 28 wherein said sensor is shaped to comprise a disposable flow channel that is removably clamped onto a microsensor sensor chip by a material that facilitates heat transfer and which is disposable upon completion of a fluid measurement thereof.

30. The sensor of claim 27 wherein said film comprises at least one thin metal film layer, wherein said thin metal film layer comprises a self-supporting layer.

31. The sensor of claim 30 wherein said thin metal film layer is laminated with an electrical insulating material provide hermetic sealing thereof.

32. The sensor of claim 31 wherein said particular material comprises a polymeric material.

33. The sensor of claim 32 wherein said polymeric material comprises a polymer-metal.

34. The sensor of claim 33 wherein said polymeric material comprises a polymer-metal-polymer.