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PCB Design: High Speed Flexi

IntroductionProcessor Card Challenges

Our client’s goal was to develop a flexi rigid that would cater for high speed and power signals while meeting all resistance, crosstalk and mechanical requirements.

 

 

 

Challenges

  • Identify required Flexi rigid design technology and manufacturing requirements.
  • To ensure correct positioning of connectors and mechanical features to ensure first time fit.
  • Identify all high speed design rules, impedance, skew, differential pairs, power rating and track widths to support resistance ratings.

 

 

High Speed Flexi

Solution

  • Partition design between high current and high speed signals and allocating signals to layers with the appropriate copper weight.
  • Develop layer build with close cooperation with the flexi manufacturer.
  • Utilising high speed design software to implement and verify that the design met all high speed rules.
  • Constantly review track resistance ratings, as small changes in length could mean a signal becomes non compliant.

 

 

 

Results

  • Depending on market forces, it was found that the copper thickness supplied to manufacturers could be at the lower end of the tolerance specification. Once the flexi manufacturer prepared the material for use the finished copper thickness could be 20% less than expected. The design had to be constructed to allow for the copper weight to vary between its minimum and maximum values to ensure the resistance criteria were met.
  • Creation of a track resistance calculator.

 

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What our customer said

“Quantum added significant value to this project from the outset. Working closely with the manufacturer Quantum developed a robust design that provided high yields in manufacture, meeting all design requirements regardless of raw material variations”

— Director Device Engineering

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