Don'ts of Flex Circuit

  1. shangahiEPCB
    Flex circuits are largely used in PCB fabrications, EPCB found that most of us didnít pay enough attention to those problems, such as the layer stack design, parts placement, cutouts, etc. But remember that flex circuits have some gnarly material quirks which range from relatively high z-axis expansion coefficients of adhesives, to the lower adhesion of copper to PI substrate and coverlay, to copperís work hardening and fatigue. These can be compensated for largely by following some doníts.

    Donít bend at corners. It is generally best to keep copper traces at right-angles to a flex-circuit bend. However there are some design situations where itís unavoidable. In those cases you should keep the track work as gently curving as possible, and as the mechanical product design dictates, conical radius bends is a better way.

    Donít change widths unexpectedly. Whenever you have a track entering a pad, particularly when there is an aligned row of them as in a flex-circuit terminator, this will form a weak spot where the copper will be fatigued over time. Unless there is going to be stiffener applied or a one-time crease, itís advisable to taper down from the pads.
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