Material Choices for High-Speed Flexible Circuits


Reading time ( words)

Abstract

High-speed rigid boards have existed for many years, with fluoropolymers being the most common dielectric used. More recently, flexible circuit materials have been developed, and these new products use a variety of polymer (including fluoropolymers) and composite film approaches to allow high-speed flex circuits. This article will provide guidelines on how to compare the different options. The electrical benefits of the different polymers and constructions will be reviewed as well as the physical and flexible properties of different constructions. As with any new materials, the ease of processing is an important consideration, especially since some of these new products use thermoplastic adhesives or require high-temperature lamination of bondplies and coverlays.

Introduction

High-speed rigid boards have existed for many years and continue to improve. Initially, most high-speed rigid boards used fluoropolymer dielectrics (fluorine-containing polymers like Teflon®). Now many new dielectrics have been developed for high-speed rigid boards, which has broadened both the material supplier base and the number of fabricators that can make high-speed rigid boards.

Materials for high-speed flexible circuits are a much more recent development. This article will review the key material choices for making high-speed flexible circuits while also explaining why older flex materials were not a good choice for today’s high-speed circuits.

When talking about high-speed circuits, we are really talking about controlled impedance applications. This could be either microstrip or stripline designs. This paper will discuss flexible clads, as well as bondplies and coverlays. For controlled impedance circuits, the electrical properties of the clad and bondplies are critical for striplines. The electrical properties of the clad and coverlay are critical for microstrips. 

To read the full version of this article which appeared in the April 2017 issue of The PCB Magazine, click here.

Share


Suggested Items

Weiner’s World—August 2017

09/04/2017 | Gene Weiner, Weiner International Inc.
IPC is planning to hold a special meeting on automotive electronics for senior executives during IPC APEX EXPO 2019. The meeting will be planned and produced by the IPC Ambassador Council. Its presentations will feature senior members of the entire automotive electronics supply chain.

Laser Patterning & Metallization to Reduce Process Steps for PCB Manufacturing

08/29/2017 | Joel Schrauben, Cameron Tribe, Christopher Ryder and Jan Kleinert, ELECTRO SCIENTIFIC INDUSTRIES
This paper details a new methodology for the plating of conductive features onto glass dielectrics. A laser is used to ablate material from a glass substrate in the desired pattern, and copper is “seeded” into these features using laser-induced forward transfer of a copper foil.

Mr. Laminate Tells All: PTFE is About to be Banned by IEC TC111

07/10/2017 | Doug Sober, Essex Technologies Group, with Stephen Tisdale, Tisdale Environmental Consulting LLC
There, I said it. Technical Committee 111 of the International Electrotechnical Commission (IEC) is preparing to effectively ban PTFE (polytetrafluoroethylene) materials from electronics. As history goes, the electronics industry has focused on only two of the four halogens (bromine and chlorine) to be limited in order to be called “halogen-free” or more accurately “low-halogen.” But now, fluorine is being dragged down too, just because of its location in the periodic table.



Copyright © 2017 I-Connect007. All rights reserved.