MEP EP#262: Flex PCB Primers

Parker

• Robert Feranec
  • Published a video about what to consider when selecting chips for your new board design.
    • Don’t want to steal Robert's content so go check him out.
  • Hardware design and PCB Layout online course
• Comprehensive Power Supply System Designs for Harsh Automotive Environments Consume Minimal Space, Preserve Battery Charge, Feature Low EMI
  • Analog engineer Bin Wu and previous Linear Tech engineer Zhongming Ye writing an application note with linear tech devices.
  • ‘An Ideal Diode Satisfies Automotive Immunity Norms’
    • LT8672
      • Active rectifier controller
  • Why is all this needed?
    • Car power is dirty
      • Load dumps
      • Cold cranking
      • Pulses
        • ISO 7632-2 is a negative spike whose peak voltage exceeds −220 V!
      • Reverse Polarity
      • AC Ripple

Stephen

• Wurth Elektronik on Flex PCBs
  • Basically Polyimide foil with deposited copper
  • 3 ways to create a system (from page 2)
    • Heterogeneous
    • Homogeneous
    • Partial Homogeneous
  • Full flex and Semiflex
  • Much Much easier way to create a 3d system design
  • Added benefit of having a full panelized system
    • Can test a full panel of designs all at once
    • Test points can technically be on the flex
  • Break and make
    • Take the rails off of the PCB
  • Flex-rigid boards
    • Can be bonded to external layers
    • Can be internal
    • Can be rigid on one side or both
    • Can be multiple layers
  • Layout and routing
    • Create a new layer in your EDA tool to define the Flex portion
    • No vias in flex portion
    • Use teardrops for added rigidity
    • Use wider tracks where possible for added strength
    • Do not change width in bend area
    • Distribute conductors evenly
  • Documentation
    • Do it... Do it a lot
    • In addition to the PCB gerber or ODB++ files include drawings
    • A fab drawing that defines the flex pcb is very helpful