Method of forming an electronic pressure sensitive transducer on a printed circuit board

• US 7,213,323 B2
• Filed: 02/16/2005
• Issued: 05/08/2007
• Est. Priority Date: 02/08/2001
• Status: Expired due to Term

• Current Assignee: Interlink Electronics Incorporated
• Original Assignee: Interlink Electronics Incorporated
• Inventors: Baker, Jeffrey R., Sanchez, Carlos S., Bair, Patrick H.
• Primary Examiner(s): Kim; Paul D.
• Application Number:
  US11/058,939
• Publication Number:
  US 20050156705A1
• Time in Patent Office: 811 Days
• Field of Search: 295/921, 295/95, 298/31, 298/32, 298/41, 338/5, 338/47, 338/99, 338/114, 338/128, 438/48, 439/79
• US Class Current: 29/595
• 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
• 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
• 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. A method of forming an electronic pressure sensitive transducer on a printed circuit board, the printed circuit board accepting a plurality of electronic components for processing signals generated by the pressure sensitive transducer, the method comprising:

forming a first plurality of conductive traces on the printed circuit board to form a contact area;

forming a pedestal on the printed circuit board substantially around the contact area, with a second plurality of conductive traces the second traces formed on the printed circuit board in the shape of the pedestal and covered with a non-conducting material;

depositing at least one resistive layer on an inner side of a flexible substrate; and

assembling the flexible substrate on the printed circuit board such that the flexible substrate resistive layer is facing the printed circuit board conductive traces, the flexible substrate held to the printed circuit board by an adhesive substantially surrounding at least a portion of the contact area and contacting the pedestal.

2. The method of forming an electronic pressure sensitive transducer on a printed circuit board as in claim 1 wherein at least one resistive layer comprises resistive ink.

3. The method of forming an electronic pressure sensitive transducer on a printed circuit board as in claim 1 wherein assembling comprises screen printing the adhesive on at least one of the flexible substrate and the printed circuit board.

4. The method of forming an electronic pressure sensitive transducer on a printed circuit board as in claim 1 wherein the traces forming the pedestal are formed in the same process as the traces forming the contact area.

5. The method of forming an electronic pressure sensitive transducer on a printed circuit board as in claim 1 wherein the first plurality of conductive traces are formed as a plurality of sets of zonal traces, each set of zonal traces interconnected within a zone of the contact area, and as an interconnected set of common traces extending into each zone.

6. The method of forming an electronic pressure sensitive transducer on a printed circuit board as in claim 1 wherein forming a first plurality of conductive traces comprises depositing an oxidation preventing conductive material over copper traces.

7. The method of forming an electronic pressure sensitive transducer on a printed circuit board as in claim 1 wherein forming a first plurality of conductive traces comprises screen printing a carbon ink.