MEP EP#262: Flex PCB Primers

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