Supplying pressure relief at the edges of supports assists to prevent tension risers from occurring at flex-to-rigid change. Tearing of the flex PCB or splitting of the copper at the shift point could happen more conveniently if the treatment is omitted from the design or manufacturing procedure. One or both of the adhering to techniques need to be made use of for flex PCB.
ROUNDED STIFFENER EDGES AT TRANSITION
In areas where the flex circuits egresses from the perimeter of the support, the support edges ought to be rounded or provided with a radius at the side to avoid a factor of focused anxiety. Alternatively, breaking the side of the rigid stiffener with a documents or sandpaper at the shift side before assembly could supply a similar benefit.
FILLET TRANSITION EDGE OF STIFFENER
Filleting of the shift side of a support with a resilient glue or epoxy is an additional typical method of stress relieving flex PCB circuits. The small grain of a suitable polymer will certainly offer a basic means of transitioning stress from the stiffener to the flex PCB circuits. Number 7-28 highlights both techniques.
STRESS RELIEF FOR UNSUPPORTED FLEX circuits
Stress relief must likewise be provided for when placing the completed flex PCB or assembly. The complying with techniques can be utilized for this objective:
– Break or span sharp edges of any type of keeping bars or clamps that might be utilized to hold the flexible circuits in position.
– Use a low modulus, elastomeric product between the limiting bar and the flex PCB.
– Bond the circuits to the assembly real estate utilizing a double-backed sticky foam material or simple pressure-sensitive adhesive.
– Use a low modulus, elastomeric product between the limiting bar and the flex PCB.
– Bond the circuits to the assembly real estate utilizing a double-backed sticky foam material or simple pressure-sensitive adhesive.
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