Mounting Standard
Standardized installation protocols govern the physical bonding of resistance strain gauges to metallic or composite circuit structures. Adherence to astm e1237 ensures that mechanical strain transfers from the substrate to the foil grid without bond line slippage. The specification applies strictly to surface preparation, adhesive selection, and clamping pressures during sensor attachment.
Bond Line
Solvent degreasing and mechanical abrasion prepare the target circuit trace or board substrate prior to chemical etching. A thin, uniform adhesive layer prevents creeping under mechanical strain, whereas excess bond line thickness introduces parasitic compliance into force measurements. Surface neutralisation neutralizes acidic residues left by liquid etchants before liquid adhesive dispensing begins.
Thermal curing cycles must follow controlled temperature ramps to mitigate residual stresses that degrade measurement repeatability during thermal cycling. High moisture environments degrade adhesive bonds over time, shifting zero reference offsets during long term reliability testing. Failure to maintain uniform clamping force across the gauge grid generates localized stress concentrations that alter zero strain resistance readings.
Inspection Resistance
Electrical resistance measurements verify the integrity of the installed grid before applying protective potting materials. Deviations exceeding point five percent from nominal resistance indicate gauge distortion or improper alignment during clamping. Ground isolation testing confirms that insulation resistance between the sensor foil and substrate exceeds ten gigohms at fifty volts direct current.
Incorrect surface neutralisation leaves chemical residues that corrode sensor pads under bias voltage.
