Reading time ( words)
I am always surprised when a colleague produces a statement about PCB laminates that seems incorrect or out of date. This need not happen today as the specialists at Isola have written an excellent book about high performance materials, now available for download from I-Connect007.
Author Michael Gay, a 25-year veteran of laminate manufacturing, meticulously guides readers through the most pertinent questions regarding rigid laminates. This is essential information for everyone, including the experts, because the materials and applications for laminates in printed circuits are constantly changing. Fortunately, Michael focuses on the basics of high-performance materials being used in today’s printed circuit boards.
And Isola should know. The company has been making high-performance and advanced materials for the electronics industry since 1956, remaining among only a handful of companies producing these materials. As the basis for all printed circuit boards, laminate is the major cost driver for PCBs and determines much of its electrical performance. To understand and design printed circuits, you first must understand the PCB materials.
In The Printed Circuit Designer’s Guide to… High Performance Materials, Michael first provides a brief history of laminates in this industry. He then proceeds to deliver a thorough education of laminates. But what does that look like?
It starts with resin systems (there are many), while including the role of fillers (again, many) and flame retardants. Next are the reinforcements, especially glass fabrics which must include the types of glass—glass styles, glass weaves, and glass constructions (i.e., spread glass). This is followed by how you use the prepregs (glass fabrics impregnated with resin and partially cured) and multilayer material constructions. Topics like “range of fill capabilities,” “dielectric properties,” and “stackup advice”—including calculating impedances—come into the picture.
Add copper foil, the final element to prepreg, and you have a rigid laminate. But all copper foils are not created equal, so the author covers surface treatments and roughness, especially for high-frequency skin effect.
This book concludes with more information about electrical performance and, particularly, the growing automotive use of laminates when voltages and currents are particularly high but subjected to the environmental extremes that automobiles will see.
This is where you must start, but not where you will end. Visit the I-007 eBook library to find other titles in The Printed Circuit Designer’s Guide to… series covering PCB materials for flex, rigid-flex, and more on electrical performance.
Happy Holden has worked in printed circuit technology since 1970 with Hewlett-Packard, NanYa Westwood, Merix, Foxconn, and Gentex. He is currently a contributing technical editor with I-Connect007, and the author of Automation and Advanced Procedures in PCB Fabrication, and 24 Essential Skills for Engineers. To read past columns or contact Holden, click here.