Electronic pressure sensitive transducer apparatus and method for manufacturing same

• US 6,909,354 B2
• Filed: 02/05/2002
• Issued: 06/21/2005
• Est. Priority Date: 02/08/2001
• Status: Active Grant

• Current Assignee: Interlink Electronics Incorporated
• Original Assignee: Interlink Electronics Incorporated
• Inventors: Baker, Jeffrey R., Sanchez, Carlos S.
• Primary Examiner(s): Easthom, Karl D.
• Application Number:
  US10/067,952
• Publication Number:
  US 20020104369A1
• Time in Patent Office: 1,232 Days
• Field of Search: 338/47, 338/5, 338/128, 338/92, 338/95, 338/114, 338/99
• US Class Current: 338/47
• CPC Class Codes: G01L 1/20 by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids of piezo-resistive materials G01L1/18; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
• CPC Class Codes: G01L 1/205 using distributed sensing elements
• CPC Class Codes: H01H 13/702 with contacts carried by or formed from layers in a multilayer structure, e.g. membrane switches
• CPC Class Codes: H01H 2201/036 Variable resistance
• CPC Class Codes: H01H 2203/02 Interspersed fingers
• CPC Class Codes: H01H 2239/01 combined with other elements on the same substrate
• CPC Class Codes: H05K 1/0268 for electrical inspection or testing
• CPC Class Codes: H05K 1/11 Printed elements for providing electric connections to or between printed circuits
• CPC Class Codes: H05K 1/141 One or more single auxiliary printed circuits mounted on a main printed circuit, e.g. modules, adapters H05K1/142 and H05K1/147 take precedence
• CPC Class Codes: H05K 1/167 incorporating printed resistors
• CPC Class Codes: H05K 2201/035 Paste overlayer, i.e. conductive paste or solder paste over conductive layer
• CPC Class Codes: H05K 2201/09663 Divided layout, i.e. conductors divided in two or more parts branched layout H05K2201/09254
• CPC Class Codes: H05K 2201/10151 Sensor
• CPC Class Codes: H05K 2201/2036 Permanent spacer or stand-off in a printed circuit or printed circuit assembly pattern for applying drops or paste H05K2203/0545
• CPC Class Codes: H05K 2203/0278 Flat pressure, e.g. for connecting terminals with anisotropic conductive adhesive
• CPC Class Codes: H05K 3/249 comprising carbon particles as main constituent
• CPC Class Codes: H05K 3/305 Affixing by adhesive
• CPC Class Codes: H05K 3/365 by abutting, i.e. without alloying process
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49007 Indicating transducer
• CPC Class Codes: Y10T 29/49128 : Assembling formed circuit to base
• CPC Class Codes: Y10T 29/4913 : Assembling to base an electrical component, e.g., capacitor, etc.
• CPC Class Codes: Y10T 29/49146 : with encapsulating, e.g., potting, etc.

Abstract

The cost and complexity of an electronic pressure sensitive transducer are decreased by constructing such a transducer directly on a printed circuit board containing support electronics. Conductive traces are formed on the printed circuit board to define a contact area. A flexible substrate having an inner surface is positioned over the contact area. An adhesive spacer, substantially surrounding the contact area, attaches the flexible substrate to the printed circuit board. At least one resistive layer is deposited on the flexible substrate inner surface. In use, the resistive layer contacts at least two conductive traces in response to pressure applied to the flexible substrate to produce an electrical signal indicative of applied pressure.

Claims

1. An electronic pressure sensitive transducer producing an electrical signal indicative of applied pressure, the transducer comprising:

a printed circuit board;

a plurality of conductive traces formed on the printed circuit board to define a contact area;

a flexible substrate having an inner surface positioned over the contact area;

an adhesive spacer and a pedestal substantially surrounding the contact area, the adhesive spacer and the pedestal attaching the flexible substrate to the printed circuit board, the pedestal comprising conductive material delineating the contact area on the printed circuit board; and

at least one resistive layer deposited on the flexible substrate inner surface, the resistive layer contacting at least two of the traces in response to pressure applied to the flexible substrate to produce the electrical signal indicative of applied pressure.

2. An electronic pressure sensitive transducer as in claim 1 wherein at least one resistive layer comprises resistive ink.

3. An electronic pressure sensitive transducer as in claim 1 wherein the pedestal conductive traces are covered with a non-conductive material.

4. An electronic pressure sensitive transducer as in claim 1 wherein the plurality of conductive traces comprise:

a plurality of sets of traces, each set of traces interconnected within a zone of the contact area; and

an interconnected set of common traces extending into each zone.

5. An electronic pressure sensitive transducer as in claim 4, wherein at least one interconnected set of traces is connected to electronic elements soldered to the printed circuit board for processing the transducer electrical signal via a through-hole in the printed circuit board.

6. An electronic pressure sensitive transducer as in claim 5 wherein the through-hole is within the contact area.

7. An electronic pressure sensitive transducer as in claim 1 wherein conductive traces are arranged in interconnected sets, with at least two sets of traces interdigitated.

8. An electronic pressure sensitive transducer as in claim 1 wherein conductive traces comprise copper traces covered with an oxidation preventing conductive material.

9. An electronic pressure sensitive transducer as in claim 1 wherein conductive traces comprise screen printed carbon ink.

29. An electronic pressure sensitive transducer as in claim 1 further comprising electronic components soldered to the printed circuit board, the electrical components receiving electrical signals from the plurality of conductive traces defining the contact area.

10. A printed circuit board electronic pressure sensitive transducer assembly comprising:

a printed circuit board manufactured to accept a plurality of electronic elements for processing pressure transducer electrical signals;

a plurality of conductive traces formed on the printed circuit board to define a contact area;

a flexible substrate having an inner surface positioned over the contact area;

an adhesive spacer and a pedestal substantially surrounding the contact area, the adhesive spacer and the pedestal attaching the flexible substrate to the printed circuit board, the pedestal formed of conductive material delineating the contact area on the printed circuit board; and

at least one resistive layer comprising a resistive ink deposited on the flexible substrate inner surface, the resistive layer contacting at least two of the contact area conductive traces in response to pressure applied to the flexible substrate.

11. A printed circuit board electronic pressure sensitive transducer assembly as in claim 10 wherein the pedestal a conductive material is coated with a non-conductive material.

12. A printed circuit board electronic pressure sensitive transducer assembly as in claim 10 wherein the plurality of conductive traces comprise:

a plurality of sets of traces, each set of traces interconnected within a zone of the contact area; and

an interconnected set of common traces extending into each zone.

13. A printed circuit board electronic pressure sensitive transducer assembly as in claim 12 wherein at least one interconnected set of traces is connected to the electronic elements for processing the transducer electrical signal via a through-hole in the printed circuit board.

14. A printed circuit board electronic pressure sensitive transducer assembly as in claim 13 wherein the through-hole is within the contact area.

15. A printed circuit board electronic pressure sensitive transducer assembly as in claim 10 wherein conductive traces are arranged in interconnected sets, with at least two sets of traces interdigitated.

16. An electronic pressure sensitive transducer as in claim 10 wherein the adhesive spacer comprises adhesive ink.

17. A printed circuit board electronic pressure sensitive transducer assembly as in claim 10 wherein conductive traces comprise copper traces covered with an oxidation preventing conductive material.

18. A printed circuit board electronic pressure sensitive transducer assembly as in claim 10 wherein conductive traces comprise screen printed carbon ink.

20. A printed circuit board electronic pressure sensitive transducer assembly as in claim 10 wherein the pedestal is formed by depositing a non-conductive layer over a conductive layer, the conductive layer formed on the printed circuit board.

19. A printed circuit board electronic pressure sensitive transducer assembly comprising:

a printed circuit board including accepting a plurality of electronic elements for processing pressure transducer electrical signals;

a plurality of conductive traces formed on the printed circuit board to define a contact area;

a pedestal substantially surrounding the contact area, the pedestal forming a flat area higher than the conductive traces, the pedestal comprising the same conductive material used to form the conductive traces the material delineating the contact area;

a flexible substrate having an inner surface positioned over the contact area;

an adhesive spacer substantially surrounding the contact area, the adhesive spacer attaching the flexible substrate to the pedestal; and

at least one resistive layer deposited on the flexible substrate inner surface, the resistive layer contacting at least two of the contact area conductive traces in response to pressure applied to the flexible substrate.

21. An electronic pressure sensitive transducer as in claim 19 wherein at least one resistive layer comprises resistive ink.

22. An electronic pressure sensitive transducer as in claim 19 wherein the adhesive spacer comprises adhesive ink.

23. A printed circuit board electronic pressure sensitive transducer assembly as in claim 19 wherein the plurality of conductive traces comprise:

a plurality of sets of traces, each set of traces interconnected within a zone of the contact area; and

an interconnected set of common traces extending into each zone.

24. A printed circuit board electronic pressure sensitive transducer assembly as in claim 23 wherein at least one interconnected set of traces is connected to the electronic elements for processing the transducer electrical signal via a through-hole in the printed circuit board.

25. A printed circuit board electronic pressure sensitive transducer assembly as in claim 24 wherein the through-hole is within the contact area.

26. A printed circuit board electronic pressure sensitive transducer assembly as in claim 19 wherein conductive traces are arranged in interconnected sets, with at least two sets of traces interdigitated.

27. A printed circuit board electronic pressure sensitive transducer assembly as in claim 19 wherein conductive traces comprise copper traces coated with an oxidation preventing conductive material.

28. A printed circuit board electronic pressure sensitive transducer assembly as wherein conductive traces comprise screen printed carbon ink.