Seminar: Exploring PCB Routing, Grids and BGA Design for Quality Boards by Susy Webb
Senior PCB Design Engineer
Date and time:
October 26th, 2023
From 9:00 AM to 4:00 PM Pacific time
Location: This event will be hosted online via Zoom
The way a PCB is routed can be very important to the board’s ability to do its work. In order to get the best performance, the design must have a plan that starts with the placement, considers the electrical needs of the signals, is routed in an efficient manner and is manufacturable.
In this presentation, we will start with the discussion of ways to place parts to set up the routing to come, then review the science for good quality signals including rise time, return path, impedance control, critical signals, and differential pairs. Next, we will decide which signals to route in which order, what layers we might use for each type of signal or bus, and where they will go if they must change layers in the stack.
Efficient routing might also include the use of through hole or microvia grids and patterns to maximize the number of signals that can flow through any area of the board. Those grids keep the placement of vias from being randomly placed which can easily block routing, and can allow for more routing on other layers as well. Gridded patterns can also maximize fanout possibilities for BGAs, and we will discuss lots of via grid patterns for different size, type and pitch of BGAs.
Power and stack-up control must also be considered for optimizing BGAs routes, so we will explore that information next. Finally, there will be some manufacturing issues that have to do with the small trace widths and pad sizes used on the BGAs plus other concerns for routing designs that will be pictured and explained.
• Placement guidelines to set up routing
• Discussion of the electrical needs – rise time, return path, impedance control, critical signals, differential pairs
• Routing order
• Layer usage for each type of signal/bus
• Signals changing layers
• Through hole and microvia routing grids and patterns
• No random placement of vias allows for more routing
• Gridded patterns will maximize fanout and routing possibilities for BGAs
• Examples of gridded patterns for size, type, and pitch of BGAs
• Power and stack-up control for ICs and BGA routes
• Manufacturing issues for small trace widths and pad sizes used on BGAs, and other concerns for routing
About Susy Webb
Susy Webb is a senior PCB design engineer with over 45 years of experience. Her career includes experience in coastal and oceanographic oil exploration and monitoring equipment, point-to-point microwave network systems, and CPCI and ATX computer motherboards. Webb is a regular speaker at PCB Conferences, IPC events, international design conferences, and has consulted for individual companies and groups as well for the last 18 years.. Her presentations discuss practical implementation of complex engineering concepts into board layout, and methods to improve the overall design and flow of printed circuit boards. She is CID certified, a former writer/columnist for Printed Circuit Design and Fab magazine, a chapter writer for Clyde Coombs “Printed Circuits Handbook”, one of the writers of the PCB-EDU book and curriculum, and one of the judges for the annual TLA competition. Webb is also an active member of the PCEA Executive Board and education committees, and is a member and past president of the Houston Chapter of the Designer’s Council.