Interlink Electronics Micro Joystick - Manual (Page 20)

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18
MicroJoystick
Integration Guide
Pressure-Sensitive Z-axis Adhesives
Z-axis conductive adhesive offers an inexpensive and, if used correctly, a reliable means of
connecting FSRs to flexible circuit tails. The Z-axis adhesive used by Interlink Electronics
is .05mm thick and is manufactured by 3M Corporation (Scotch™ brand number 9703). When
handling the sensor, care should be taken to prevent touching and to prevent wrinkling of the
adhesive. This can lead to a short, leakage in the X and Y directions, or an open circuit. Since
the Z-axis adhesive does not provide a strong mechanical bond, a compressive force to the
connection joint should be devised. Applying pressure to the connection joint will prevent
delamination of the adhesive which can lead to an open circuit. For example, a rib could be
designed into the assembly to apply pressure to the joint. Rubber could be used on the end of the
rib to take up tolerances in the design.
Using a Rib to Compress the Adhesive Joint
The compressive force on the joint should be applied within a few minutes of assembling the FSR
to the flexible tail. This will help prevent the Z-axis adhesive from delaminating and being
exposed to contaminants. If the Z-axis tape is exposed to contaminants, the electrical conductivity
of the tape can be permanently impaired even with the application of pressure to the bond joint.