Being aware of, and successfully navigating the pitfalls of designing and fabricating multilayer, high performance Printed circuit boards

2. Who are We?
 Michael Ingham
Michael Ingham specializes in the design and development of multilayer PCBs
for RF and ultra High-Speed Digital applications. He has held engineering
positions with Vitesse Semiconductor and Intel and is currently a Principle
Design Engineer with Spectrum Integrity, Inc. where he primarily focuses on
10GHz to 50GHz applications. He has completed hundreds of successful designs
and is often consulted with to identify and solve signal integrity issues. Michael
holds BSEE from California Polytechnic University, San Luis Obispo, and a Sr.
Member of IEEE.
Judy Warner
Judy Warner has nearly two decades of experience in the Printed Circuit Board
Manufacturing Industry. She is the director of Sales and Marketing for Transline
Technology, whose focus is on RF/MW and High Performance PCBs. She is an
author of a current blog that is hosted by Printed Circuit Design and Fabrication
and Microwave Journal websites. The blog focuses on RF/MW and High
Performance PCB manufacturing.

3. The Problem
The are gaps of knowledge and understanding that exist
between Engineering, Design, and Manufacturing
This is Particularly true in the area of High Performance
Multilayer PCBs
Most of us are not aware that these gaps exist and therefore
fall into “pitfalls” that cause much needless frustration
and failure!

4. What creates these Gaps?
 Many CAD Programs allow for any design to be created without regard to
the “real world” viability for a PCB to be manufactured. As the software
manufacturers have removed the stop-gaps, to allow for more flexibility and
innovation, they have taken out the some safeguards that would prevent
design engineers from unwittingly creating designs that are unfit or
impractical for manufacturing.
 Integrative courses have been removed at Academic levels
Fundamental understanding of Design and Mfg not being taught to
engineers and increased demands for specialization leads to lack of
exposure to design and manufacturing principles
 RF techniques are very different than digital design, yet digital
designers are being increasingly called upon for High-speed digital
and RF designs

5. It Starts with the Design and High
Performance Expertise
 High Performance designs are not straight
forward builds that rely only on the fabricator
and material suppliers
 High Performance Expertise is needed at the
design, layout and fabrication levels
 Synergy between disciplines
is key to success

6. The Conundrum of the
Non- Homogenous design
 The last decade’s evolution and emergence of
high speed digital.
 Mixing Dielectrics
(Unlike Materials)
 Materials

7. Common Pitfalls:
Specifying an overrated
material.
 The lowest loss tangent is not always the
best choice!
 Looking at the Big Picture when selecting
materials
 Addressing Conductive Loss
 Low dielectric materials are more costly,
and typically more difficult to use in
manufacturing

8. Common Pitfalls:
Stack-ups that are not fit for manufacturing
 Knowing your pre-pregs, bond plies and cores.
 Variances of final product
 Reading the fine print on the data sheets
 Partnering with you Advanced Material Division
Representatives and your design and fabrication
suppliers

9. Common Pitfalls:
Unbalanced Stack-ups
 Temperature Issues
 Warping
 Latent Problems

10. Common Pitfalls
Unrealistic Tolerances
 Lack of knowledge of process capabilities
and limitations, set up unrealistic
expectations
 The benefits of partnering with your board
supplier and/or layout engineers

11. Common Pitfalls
Very thin transmission lines
 Impedance issues
 Very “lossy”
 Manufacturing challenges

12. Common Pitfalls

13. Common Pitfalls
Poor Documentation and Data Problems
 Fab drawings should NOT be optional!!!
 Accurate drawings are imperative to success
 Careful DRC before releasing gerber data

14. Keys to Success
 Identifying Expertise
 Avoid the Pitfalls!
 Communication
 Partnerships
(Self-directed
continuing education!)
 Creating Win-wins