Defects and
Signal Integrity

     
   

Background: Endicott Interconnect Technologies, a manufacturer of printed circuit boards, requires high speed data rate modeling characteristics to assess the electrical performance of their product. Understanding how line trace variations influence high frequency signal integrity will provide knowledge to further enhance the efficiency of the manufacturing process and quality of production of printed circuit boards.

Objective: Evaluate effects of neck-down defects on signal integrity of circuit board traces.

 

Approach: Interpret Scatter-Parameters (S-Parameters) and Time Domain Reflectometry (TDR)  measurements of circuit board traces using microwave simulations and sample measurements. Simulations developed using Microwave Office software and sample measurements conducted with a probe station and a network analyzer. Compare the simulations and sample measurements to validate the results.

 

Results:

 

Figure 1 shows an example of a circuit trace simulated with Microwave Office. Reflection from the first port (Γ1), the second port (Γ2), and the defect(Γ2) contribute to the measured responses with the S-Parameter and TDR results.

 


Figure 1 - Trace with Reflection Coefficients

 

 

Neck-down defects, modeled both in Microwave Office and measured using a probe station and a network analyzer produced similar results for S-Parameter and TDR measurements. Both S-Parameter and TDR measurements provide unique reflection results due to the location of the defect.

 

Additionally, the measurements and simulations both indicate that neck-down defects of 30% and 50% of the line width produce minimal degradation of signal integrity.

 

 

 

Benefits to Endicott Interconnect:

  • Provide analysis of defect analysis in both time and frequency domain
  • Prove the location of the defect has effects on both TDR and S-parameters
  • Demonstrate of capabilities of Microwave Office software
  • Demonstrate useful features and limitations of simulations
  • Show how to use simulations to interpret data
  • Define steps for future teams

Recommendations for Future Studies:

  • Utilize Design Centering capabilities to find maximum acceptable defect
  • Eye Diagrams
  
     

Faculty Advisor:

Dr. Lynn Carpenter

Team Members:

Keith Ahlbrandt

Colleen Matthews

Randy Stanger

EI Contacts:

Dave King

Steve Rosser

Subahu Desai
     

EE 403W: Endicott Interconnect Senior Design Project - Last Updated: December 08, 2003