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Browse Prior Art Database

STRAIN GAGES IMBEDDED IN PC BOARD

IP.com Disclosure Number: IPCOM000007600D
Original Publication Date: 1996-May-01
Included in the Prior Art Database: 2002-Apr-09
Document File: 2 page(s) / 82K

Publishing Venue

Motorola

Related People

Larry Marvet: AUTHOR [+4]

Abstract

Electronic circuit board strain due to bending determination. Strain gages are comprised of thin in manufacturing and handling contributes directly copper foil tracing a serpentine path along a pri- to surface mount solder joint failure and the result- mary axis as shown in Figure 1. They work on the ant reduction in quality. Strain gages are an impor- principal of increasing resistance ofthe copper traces tant measurement tool for printed circuit board deflec- as they are stretched or strained. The resistance tion and surface mount component reliability change is measured and calibrated in units ofstrain.

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MOTOROLA Technical Developments

STRAIN GAGES IMBEDDED IN PC BOARD

by Larry Marvet, David Reiff, Robert Darveaux and Chong Kok hat

  Electronic circuit board strain due to bending determination. Strain gages are comprised of thin in manufacturing and handling contributes directly copper foil tracing a serpentine path along a pri- to surface mount solder joint failure and the result- mary axis as shown in Figure 1. They work on the ant reduction in quality. Strain gages are an impor- principal of increasing resistance ofthe copper traces tant measurement tool for printed circuit board deflec- as they are stretched or strained. The resistance tion and surface mount component reliability change is measured and calibrated in units ofstrain.

I d

, :-FOIL TRACES 1 1

I 8 L 1

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PRIMARY AXIS OF STRAIN 4

Fig. 1

  Strain gages are fragile and must be permanently attached directly to the surface where strain meas- urement is of interest. Gage mounting requires flat surfaces and space for connecting the electrical lead wires to the gage. The board real estate and wire connection requirements are often hampered by printed circuit board component placement. These interferences severely limit the quantity and areas that strain gages can be mounted on most products.

  This disclosure alleviates mounting, interference, and connection problems associated with discrete strain gages by designing the strain gage geometry directly into the artwork of a printed circuit board. The idea utilizes printed circuit board photo- lithographic technology combined with the strain gage artwork to produce an integrated...