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

Designing with Ultra-Thin Flexible Printed Circuit Boards

07/04/2017 | Akber Roy, Rush PCB Inc.
Designing with flexible PCBs is not much different from doing the same with rigid boards, except that the designer must account for the mechanical complexity associated with flex circuits. For instance, a flexible PCB can tear if flexed beyond its capability during installation. Therefore, it is very important to create a mechanical model of the PCB and test it for a proper fit, before taking up the electrical design.

Growth Ahead for Flexible Hybrid Electronics Industry

05/25/2017 | Heidi Hoffman, SEMI
According to Zion Research, “global demand for the flexible electronics market was valued at $5.13B in 2015 and is expected to generate revenue of $16.5B by 2021, growing at a CAGR of slightly above 21% between 2016 and 2021.” Key elements of the market, in the view of most analysts, include flex displays, sensors, batteries, and memory.

Crucial Considerations for Building Flexible Heaters

04/12/2017 | John Talbot, Tramonto Circuits
An electronic heater is created by driving electric current through a resistive element. As the current is drawn through the element, some of the energy is expelled as heat. That heat can then be transferred to other surfaces with positive effects.



Copyright © 2017 I-Connect007. All rights reserved.