Interlink Electronics FSR 400 Series - Manual (Page 34)

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FSR
®
Integration Guide
9.0 FSR Usage: The Do’s and Don’ts
 Do follow the seven steps of the FSR Integration Guide.
 Do, if possible, use a firm, flat and smooth mounting surface.
 Do be careful if applying FSR devices to curved surfaces. Pre-loading of the device can
occur as the two opposed layers are forced into contact by the bending tension. The
device will still function, but the dynamic range may be reduced and resistance drift could
occur. The degree of curvature over which an FSR can be bent is a function of the size of
the active area. The smaller the active area, the less effect a given curvature will have on
the FSR’s response.
 Do avoid air bubbles and contamination when laminating the FSR to any surface. Use
only thin, uniform adhesives, such as Scotch brand double-sided laminating adhesives.
Cover the entire surface of the sensor.
 Do be careful of kinks or dents in active areas. They can cause false triggering of the
sensors.
 Do protect the device from sharp objects. Use an overlay, such as a polycarbonate film
or an elastomer, to prevent gouging of the FSR device.
 Do use soft rubber or a spring as part of the actuator in designs requiring some travel.
 Do not kink or crease the tail of the FSR device if you are bending it; this can cause
breaks in the printed silver traces. The smallest suggested bend radius for the tails of
evaluation parts is about 2.5 mm. In custom sensor designs, tails have been made that
bend over radii of 0.8 mm. Also, be careful if bending the tail near the active area. This
can cause stress on the active area and may result in pre-loading and false readings.
 Do not block the vent. FSR devices typically have an air vent that runs from the open
active area down the length of the tail and out to the atmosphere. This vent assures
pressure equilibrium with the environment, as well as allowing even loading and
unloading of the device. Blocking this vent could cause FSRs to respond to any actuation
in a non-repeatable manner. Also note that if the device is to be used in a pressure
chamber, the vented end will need to be kept vented to the outside of the chamber. This
allows for the measurement of the differential pressure.
 Do not solder directly to the exposed silver traces. With flexible substrates, the solder
joint will not hold and the substrate can easily melt and distort during the soldering. Use
Interlink Electronics standard connection techniques, such as solderable tabs, housed
female contacts, Z-axis conductive tapes, or ZIF (zero insertion force) style connectors.
 Do not use cyanoacrylate adhesives (e.g. Krazy Glue) and solder flux-removing agents.
These degrade the substrate and can lead to cracking.
 Do not apply excessive shear force. This can cause delamination of the layers.
 Do not exceed 1mA of current per square centimeter of applied force (actuator area).
This can irreversibly damage the device.