Make the Right Decisions at the Right Time in the PCB Design Process


Reading time ( words)

The right decisions are not always the easiest decisions, but making them well and as early as possible often avoids errors and addition costs. This is certainly the case in PCB design and a key decision influencing the design process and the eventual outcome is the selection of material and of the materials vendor. This is even more important when the PCB requires significant performance parameters to be met, such as high speeds.

What I am not trying to do is teach hardware or PCB design. What I am seeking to do is to consider the processes that lead to successful design and the errors that lead to risk, potential problems and compromises.

Let’s take an example of a backplane design that has been specified at 10Gbs with 100ohm impedance with a design target of 36 layers.

First, we need to ensure that we fully understand what the specification means. Are we sure we mean 10Gbs, which is a data rate in gigabits per second, and not 10Ghz, which is a frequency? Are we seeking that data rate for a single channel, or do we need that rate for a buss?  The buss speed is the total of all the channels in that buss.

The next task would be to consider the design rules we’d like to apply based on the need for 100 ohms of differential impedance using two tracks that are in harmony so that losses are minimized. The geometry of those tracks and their positioning with the PCB structure are critical to realizing a good design that can be manufactured with a good yield.

The design is only good when the specifications are met and the PCB can be manufactured with a good yield.

This article originally appeared in the March 2015 issue of The PCB Design Magazine. To read the rest of this article, click here.

Share


Suggested Items

Who Really Owns the PCB Layout?

12/08/2017 | Paul Taubman, Nine Dot Connects
In order to understand the current climate, we have to look at the division of labor that took place in electronic design about 40 years ago. The labor was divided into two processes, with the first being the design itself. This process was (and still is) owned by the electrical engineers. Though circuit design has changed, the methods for representing the circuit have not. Paul Taubman of Nine Dot Connects explains.

Cadence Allegro Pulse Extends Team Collaboration

12/06/2017 | Cadence Design Systems, Inc.
Cadence Allegro Pulse is the PCB industry’s first solution to enable extended team collaboration by providing near-real-time insights into the complexities of the electronic design process. Allegro Pulse connects management, engineering, procurement and other business stakeholders to up-to-date work-in-progress design data in a single, unified web-based platform.

Bay Area Circuits Updates InstantDFM Tool

11/29/2017 | Andy Shaughnessy, PCB Design007
Bay Area Circuits is on a quest to help PCB designers and design engineers. For the past few years, the company has been holding facility tours and open house events to help designers understand more about the fabrication process. Now, Bay Area Circuits has upgraded its free design tool, InstantDFM.com, which allows customers and non-customers alike to check manufacturability and request pricing of their jobs. At PCB West, Andy Shaughnessy spoke with President Stephen Garcia and COO Brian Paper about the new tool update, and some of the other services they offer for PCB designers.



Copyright © 2017 I-Connect007. All rights reserved.