Environmental Effects on High-frequency Material Properties


Reading time ( words)

PCBs can be subjected to a variety of environmental conditions, which can cause changes in the material and alter how a PCB operates. For those who are less familiar with circuit material properties, there is often an unrealistic expectation that material shouldn’t change electrical performance when subjected to different environments. Actually, all circuit materials will change some properties when evaluated within a changing environment. Some properties may change more than others and some materials may have more change than others, but they all do change.

The materials formulated for use in high-frequency PCB applications are formulated so that critical electrical properties have minimal change when subjected to a changing environment. In the material development process, it is always a juggling act to allow some properties to change more so other properties will change less. All engineers typically struggle with difficult tradeoffs on just about any complex engineering task, and it is no different when formulating circuit materials.

One material property which is often overlooked until a field unit failure demands attention is TCDk (thermal coefficient of dielectric constant). This property is innate to all circuit materials; however, materials not formulated for high-frequency applications often have an extremely poor TCDk. Conversely, high-frequency laminates are formulated to have good TCDk properties and as a general statement, a good value would be 50 ppm/°C or less and this value would be an absolute value in the mathematical sense. Of course, the closer the material is to zero for TCDk the better.

Read the full column here.


Editor's Note: This column originally appeared in the August 2014 issue of The PCB Design Magazine.

Share

Print


Suggested Items

Meet Patrick Crawford, I-Connect007 Columnist

05/13/2020 | I-Connect007 Editorial Team
Meet Patrick Crawford, one of our newest I-Connect007 columnists! Patrick’s columns will provide updates on IPC Design activities. He is currently the liaison to the Design Community Leadership, the industry leadership group of IPC Design. Patrick and the Design Community Leadership work to develop the IPC Design program as IPC redoubles its efforts to serve the printed board design engineering industry.

Insulectro: Educating Designers About High-Speed Materials

02/27/2020 | Real Time with...IPC
In this video interview from the show, Ken Parent, Insulectro's VP of sales and product manager, speaks with Guest Editor Kelly Dack about the company's efforts to educate engineers and designers about materials and their options and availability. Insulectro has held a series of PCB design classes and plans to keep educating designers about these high-speed materials.

Insulectro Works to Bridge the Fabricator/Designer Gap

12/19/2019 | Barry Matties, I-Connect007
Barry Matties sat down with Insulectro’s Megan Teta and Mike Creeden to discuss trends they see in the materials market and how they’re working to bridge the gap between fabrication and design, including helping designers understand what they can do to make a board more manufacturable.



Copyright © 2020 I-Connect007. All rights reserved.