Printed Flexible Electronic Devices: Signal Interface and Reliability Assessment

Cypress Monday, February 18
1:00pm to 4:00pm


  • Ryan E. Giedd, Director of Sensor Research & Development, Brewer Science

  • Rishi Patel, Senior Research Scientist, Jordan Valley Innovation Center, Missouri State University

  • Suresh K. Sitaraman, Regents’ Professor, Mechanical Engineering, Georgia Institute of Technology


Printed Flexible Electronic Devices: Signal Interface and Reliability Assessment

About the instructors: Ryan E. Giedd, Ph.D., of Brewer Science will serve as the primary instructor and has more than 25 years of experience in this field. His co-instructors also bring some very unique experience to this short course. Suresh K. Sitaraman, Ph.D., of the Georgia Institute of Technology, has much expertise in mechanical PE reliability performance standards. Rishi Patel of the Jordan Valley Innovation Center at Missouri State University brings much knowledge of printed carbon nanotube memory devices.

Simple or complex flexible printed electronic devices such as: metallic vias, traces, or semiconducting carbon nanoparticle networks, require significant signal and mechanical reliability assessment for general characterization and reporting commercial performance. Much time has been lost in advancing commercial printed electronics (PE) devices as a result of improper electronic impedance matches, poor electrical contact morphologies, and insufficient mechanical stability. In this course, we will review these issues and provide real-world solutions that are reliable and relatively easy to implement. We will identify the proper tools and give instrumentation examples for characterizing resistive, capacitive, and inductive PE elements from both an electronic and mechanical reliability perspective. We will review data analysis techniques for electronic impedance and mechanical reliability measurements with an emphasis on flexible PE devices rather than traditional approaches to characterizing rigid Si-based electronic devices. We will also discuss the effects of using polymer substrates where slow water diffusion can cause electronic signals that look like instabilities but are in reality responses to ultraslow diffusion processes and briefly discuss how to handle electrical contact to PE devices in aqueous or high-humidity environments. Finally, we will review techniques for mapping physical and mechanically induced damage in the field for PE devices.

Course Outline:

  1. Printed Electronic Device Assessment
    1. Background Morphology and Microstructure
  1. Measurements I – Electrical Contacts and Interfaces to PE Elements
    1. Fast screening and optimization
    2. Example of simple-to-use contact electrodes and electrode morphology
    3. Physical effects and spurious signals
      1. Flex/vibrational/acoustic signals
      2. Fluctuating temperature background
      3. Stability of changing relative humidity environments
    4. Using LF rather than DC
      1. Filtering advantages
      2. Current reversing advantages
      3. Fast look at higher frequencies to check for instabilities
  1. First Demonstration – A Simple, Fast Screening Electronic Measurement System
  1. Measurements II – Stability and Repeatability in PE Devices
    1. Flexible polymer substrates
      1. Long-term and short-term water absorption/desorption
      2. Static electricity and charge induction in PE semiconductors
    2. WVTR (water vapor transmission rate) and encapsulation
      1. Long-term temperature and relative humidity stability experiments
      2. Insulating encapsulants under metal layer barriers
      3. Floating gate issues
    3. Equivalent circuits for the LF and HF response of PE semiconductor films
      1. Morphological models
      2. Electrochemical models
    4. Post-processing of high-conductivity PE films
      1. Grain boundary effects
      2. Short duty cycles at ultrahigh currents
      3. Transmission line and network analyzer measurements
  1. Second Demonstration – Frequency Response Characterization of PE Films
  1. Reliability Assessment for Printed Electronics
    1. Materials of Interest
      1. Flexible Substrate Materials
      2. Printing Methods and Inks
      3. Encapsulants and Coatings
    2. Applicable Reliability Tests for Printed Flexible Electronics
      1. Overview of Standards and Guidelines
      2. Uniaxial Tests – Stretch, Bend, Fold, Twist
      3. Adhesion and Interfacial Delamination Tests
      4. Multiaxial Tests
      5. Environmental Tests
      6. Combination of Tests
    3. Damage Evolution and Analysis
      1. Stress and Strain Distribution
        1. Computational Models
        2. Experimental Techniques
      2. Imaging and Failure Analysis
  1. Third Demonstration – Reliability Tests and Damage Evolution
  1. Field Use Reliability and Mapping of Damage
    1. Overview of Field Use and Mapping in Rigid Electronics
      1. Biomedical Application
      2. Automotive Application
      3. Aerospace Application
      4. Load Sequencing and Damage Accumulation
    2. Field Use and Mapping in Flexible Electronics
      1. Wearable/Textile Application
      2. Aerospace Application
      3. Communication Platform
      4. Load Sequencing and Damage Accumulation
  1. Concluding Remarks
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