1-Day PCB Stack Up Design to Optimize Material Selection and Fabrication Techniques for Manufacturability, Reliability and Signal Integrity
Date: June 14, 2013
Location: Stockholm, Sweden
Successful fabrication of any PCB starts with selecting the right laminate materials and creating a stack up design that works. Today’s high-speed PCBs with their inherent signal integrity and power delivery requirements make it necessary to employ far more discipline in the choice of materials and the arrangement of layers in the stack up. These requirements are outside the skill set of all PCB fabricators.
The objective of this course is to guide the design engineer through the process of evaluating and selecting the right laminate for any given design and then designing a PCB stack up that meets the numerous demands of a complex, multilayer board that works right the first time.
The first portion of this class consists of a one-hour session based on information from Isola Group. Topics that will be addressed include the building blocks available for core and prepeg materials; the impact of material selection; an overview of available materials; what designers should be looking for during the evaluation and selection process and a short tutorial on isoStack, a new web-based stack up tool. and how they are used in various design implementations and what designers should be looking for during the evaluation and selection process.
The class, which delves more into the role of laminates in high-speed PCBs as well as how to create a successful stack up design, is conducted by Lee Ritchey, founder and president of Speeding Edge, he is considered to be one of the industry’s premier authorities on the design and manufacture of high-speed PCB systems. The fast data paths that are pervasive in all PCB products being currently designed make it imperative to be able to design stack ups that have predictable and repeatable impedances.
The demands addressed in this portion of the course include:
- Providing enough signal layers to allow successful routing of all signals to signal integrity rules.
- Copper thickness in planes and signal layers that meets the conductivity demands of signals and power, and at the same time, be reasonable to manufacture.
- Accounting for copper roughness and its effect on overall signal path loss.
- Specifying glass weave styles to minimize differential signal skew.
- Dealing with the combined loss from both the dielectric and the copper loss to arrive at an effective loss tangent that accurately predicts overall path losses.
- Specifying copper surface roughness to ensure repeatable loss from lot to lot and fabricator to fabricator.
- Providing enough power and layers to meet the needs of the power delivery system.
- Determining dimension trade widths and dielectric thicknesses that allow impedance targets to be met.
- Ensuring that the spacing between signal layers and their adjacent planes is thin enough to satisfy cross talk needs.
- Specifying dielectric materials that are economical to manufacture and are readily available.
- Avoiding the use of expensive techniques such as blind and buried vias and build up processing if possible.
- Providing for prototyping manufacture in one factory or country and production manufacture in another factory or country.
- Show how to document a stackup to ensure all design goals are met with finished PCBs.
The following topic areas will be covered in this portion of the course:
- How a typical multilayer PCB is built.
- Alternative PCB fabrication methods.
- Choosing a fabricator as a design partner.
- Types of signal layers.
- Alternate ways to stack layers.
- Selecting an impedance.
- Making all signal layers the same impedance.
- Selecting laminates.
- Considerations when selecting a laminate system.
- Obtaining laminate information.
- How thin should laminate and prepeg be to ensure successful manufacture.
- Laminate glass weave styles and their effect on differential skew.
- Selecting the proper copper foil thickness and surface finish.
- Calculating impedance.
- Measuring impedance.
- Impedance test structures.
- Impedance accuracy.
- Steps in designing a stackup.
- Stackup test structures.
- Accounting for resin in prepeg flowing into adjacent signal and plane layers.
- A full stackup drawing.
- Tools for creating PCB stackups.
- What about four layer PCBs.
This course is designed for all the participants in the design and fabrication process. Among those who will find it valuable are:
- Design engineers
- System architects
- EMC specialists
- Signal integrity engineers
- PCB layout professionals
- Applications engineers
- IC designers
- IC package designers
- Test engineers
- Project engineers
- Design managers
- Engineering managers
Any engineering professional who works with high speed design will understand the materials presented. No advanced mathematics are required.
The course fee includes a copy of the course slides. A signed course certificate will be prepared for each student.
About Lee Ritchey
Lee Ritchey is considered one of the industry´s premier authorities on high speed PCB and system design and fabrication. He has participated in the design of more than 4,000 high speed PCBs ranging from PC motherboards and elevator controllers to the backplanes used in terabit routers. He is currently involved in the design of several super computer class products as well as video games and servers of all kinds. The course draws substantially from this real-time experience with state of the art components, fabricators and materials. It also draws heavily on the design of backplanes and daughter boards containing thousands of 2.4, 4.8 and 9.6 GB/S signal paths.
In 2004, Ritchey was a regular columnist for EE Times and he has written many articles on high speed design for trade publications such as EDN, Circuitree and PC Design. He is the author of the books, "Right the First Time, A Practical Handbook on PCB and System Design, Volume 1 and Volume 2,” published by Speeding Edge.