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Browse Prior Art Database

EMBEDDED THERMOCOUPLE VIAS

IP.com Disclosure Number: IPCOM000008762D
Original Publication Date: 1998-Jun-01
Included in the Prior Art Database: 2002-Jul-10
Document File: 1 page(s) / 58K

Publishing Venue

Motorola

Related People

Robert Carson: AUTHOR [+2]

Abstract

Accurate temperature measurement on functional printed circuit boards (PCB) is crucial to monitoring thermal processes and heat dissipation in the con- struction and use of electrical products. Typically, thermocouple wires are physically attached to the PCB to measure temperatures associated with processes such as reflow or heat dissipation from discrete components. While this technique is reasonably successful, one might get more accurate and reliable information by using thermocouples that reside within the PCB at locations of interest, For example, a T-type thermal couple could be constructed within a PCB by a two layer laminate having copper on one side and constantan (Cu-Ni alloy) on the other. As a result of standard via creation techniques, thermocouples could be embedded throughout a PCB but have thermal sensitivity exclusively at a via location (at a solder joint or under a component, etc.).

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MOTOROLA Technical Developments

8

EMBEDDED THERMOCOUPLE WAS

by Robert Carson and John Zysk

  Accurate temperature measurement on functional printed circuit boards (PCB) is crucial to monitoring thermal processes and heat dissipation in the con- struction and use of electrical products. Typically, thermocouple wires are physically attached to the PCB to measure temperatures associated with processes such as reflow or heat dissipation from discrete components. While this technique is reasonably successful, one might get more accurate and reliable information by using thermocouples that reside within the PCB at locations of interest, For example, a T-type thermal couple could be constructed within a PCB by a two layer laminate having copper on one side and constantan (Cu-Ni alloy) on the other. As a result of standard via

creation techniques, thermocouples could be embedded throughout a PCB but have thermal sensitivity exclusively at a via location (at a solder joint or under a component, etc.).

  Several of the fabrication process steps for creating embedded thermocouple vias in a PCB are shown schematically below. A board having copper and constantan layers would first have the vias drilled (Figure A). The constantan would be masked to limit the area over which plated copper contacts the constantan layer (Figure B & C). Photo definition and etching of the top and bottom layer artwork would create thermocouple traces and leave the vias as the only temperature sensitive...