Advancing Manufacturing Technology

Reliability & Loss Properties of Copper Foils for 5G Applications

Project Leaders


Ed Kelley, Isola
 
John Andresakis, Dupont


Steven Ethridge, Dell
 

Call-for-Participation Webinar

Session 1
Thursday May 27, 2021
11:00 a.m. — 12:00 p.m. EDT (Americas)
5:00-6:00 p.m. CEST (Europe)
Registration coming soon

Session 2
Friday, May 28
7:00-8:00 a.m. CST (China)
7:00-8:00 p.m. EDT (Americas) on May 27
Registration coming soon

 

Background

Copper foil manufacturers apply surface treatments to copper foil, and PCB fabricators treat copper surfaces to improve adhesion to resin systems. This treatment is essential for PCBs to survive thermal shock during soldering operations and to ensure in-service durability. However, this treatment provides a roughening of the copper surface which can increase signal loss and have a detrimental effect on electrical performance. 
 
Therefore, very low-profile (smooth) copper surfaces with low loss dielectrics are used to reduce signal losses; however, this combination can reduce adhesion between copper and dielectric, reducing reliability. Traditional metrology for measuring copper adhesion such as peel strength are not always indicative of the durability and reliability of printed circuits fabricated with low profile copper foils and low loss dielectrics.
 
It is against this background of new PCB material developments and metrology techniques that a comprehensive study is required to provide empirical data for meaningful characterization of materials. This will: 
  • Enable commonality in specifying surface topology of copper foil and bonding treatments. 
  • Provide better assurance for meeting PCB electrical performance characteristics. 
  • Provide predictability of the durability and reliability of copper foil adhesion.
  • Reduce product qualification costs and associated timescales.

Project Focus

  • Benchmark current and previous work.
  • Review and make recommendations for standardization of nomenclature for copper surface metrology of chemical treatment prior to multilayer PCB bonding. 
  • Review and adopt non-contact profilometry methodology for various copper types and thicknesses and chemical treatment processes.
  • Determine signal loss characterization for various surface topology and profilometry results for a range of signal frequencies used in high frequency / 5G applications. 
  • Determine and characterize copper-to-dielectric bond strength methodology with consideration of multilayer PCB reliability.
     

Project Benefits & Value to Industry

The decision on choice of copper foil material and chemical pre-bond treatments requires consideration of electrical performance and PCB durability, in addition to cost penalties for over specifying for a particular application. By formulating a compendium of material performance criteria and cross referencing to a suite of existing standards, a user will be able to specify a category of materials that will meet electrical performance and reliability requirements while minimizing excessive costs through over specification. Additional cost and time savings may be realized by reducing the need for design reiteration and requalification to meet OEM specifications.
 
Successful completion of this project will:
  • Enable commonality in specifying topology of copper foil and bonding treatments. 
  • Provide better assurance for meeting PCB electrical performance characteristics. 
  • Provide predictability of durability and reliability of copper foil adhesion with respect to signal loss for various copper surface finishes.  
  • Reduce product qualification costs and associated timescales.
     

Steps for Joining the Project

Please note: iNEMI membership is required to participate in this project. Steps for joining the project follow.

For iNEMI members:
  • Complete and sign the Project Statement
  • Scan and email the completed statement to steve.payne@inemi.org

For non-members:  

Contact

Steve Payne
steve.payne@inemi.org
 

For Additional Information

Haley Fu
haley.fu@inemi.org