-
- News
- Books
Featured Books
- pcb007 Magazine
Latest Issues
Current IssueAdditive Manufacturing
In this month’s issue, we explore additive manufacturing technology for the PCB fabricator: where it stands today, the true benefits, and where it seems to be headed.
The Growing Industry
In this issue of PCB007 Magazine, we talk with leading economic experts, advocacy specialists in Washington, D.C., and PCB company leadership to get a well-rounded picture of what’s happening in the industry today. Don’t miss it.
The Sustainability Issue
Sustainability is one of the most widely used terms in business today, especially for electronics and manufacturing but what does it mean to you? We explore the environmental, business, and economic impacts.
- Articles
- Columns
Search Console
- Links
- Events
||| MENU - pcb007 Magazine
Estimated reading time: Less than a minute
Contact Columnist Form
Connecting the Dots: Nothing's Perfect - Understanding Tolerance
by Jack Olson
Yes, nothing’s perfect.
We designers do our best to maintain accuracy, but the real world produces imperfections:
- Our CAD systems assume that a drill is perfectly centered in a round pad. It never is.
- We declare specific trace widths, but when we measure them on an actual board they are always slightly thinner or thicker.
- Multiple layers are perfectly aligned on our computer screens, but the fabricators can never quite manage to duplicate it. There will always be some misregistration.
- The board design is assumed to be flat, but boards in the final product can be bowed or warped.
- We designate some traces to be impedance controlled, but our measurements differ.
I could go on and on and on, but I think you see the point. As designers, we calculate exact numbers. We design with precision. Our CAD systems show us the ideal board. In the real world, however, nothing is so precise. The final product will vary from the ideal in one way or another, but hopefully in ways that are harmless.
Editor's Note: This column originally appeared in the May 2013 issue of The PCB Design Magazine.
More Columns from Various Archived Columns
Slash Sheet Chaos: Is What You See, What You Get?Moisture in Materials: Avoiding Process Gremlins
Material Witness: Beat the Heat--A Non-Math Intro to Thermal Properties
Material Witness: Considerations in Using TC Materials for PWBs
Material Witness: Are Your Materials Up to the Challenge?
Material Witness: Thermal Oxidation of Materials, Part I
Material Witness: Thermal Oxidation of Materials, Part II
Material Witness: R.I.P. Speedboard C