Book Excerpt: 'The Printed Circuit Designer’s Guide to… High Performance Materials', Chapter 1

Reading time ( words)

Evolution of the Resin System
Most basic resin systems have been around for a long time. Here is a little timeline of developments through more recent introductions.

• In 1907, the first laminate was made with pure phenolic resin by Westinghouse in Pittsburgh, Pennsylvania. Formica became the first true sheet laminate.The first application—a radio by Paul Eisler in 1936—led to practical manufacturing for military radios in the U.S., and use of single-sided copper-clad phenolic laminate started in about 1943 using paper and cotton as the structural component. Epoxy resin was introduced shortly after in 1947.
• Still reigning as the lowest loss resin system, a PTFE, RT/Duroid^® was introduced in 1949.
• The first polyimide was discovered in 1908 by Bogart and Renshaw. However, the high heat-resistant polyimide laminate material was brought to the market in 1951.
• Isola began production of copper-clad laminate in 1956.
• Epoxy-based laminate systems followed around 1960 and used woven E-glass fabric.
• Shortly after, G-10 epoxy laminate (non-flame retardant epoxy resin plus E-glass) and a flame-retardant epoxy version called FR-4 (flame-retardant epoxy resin plus E-glass) were introduced in 1968.

From that time forward, there have been various blends, such as PPO (polyphenylene oxide)/epoxy, CE (cyanate ester)/epoxy, and polyimide/epoxy, that were created to balance properties of pure resin systems to achieve specific enhanced properties. Each new resin system was built on learning from previous products. Resin system developments for high heat applications such as LED lighting, ultra-thin non-reinforced films for capacitance and halogen-free systems to meet RoHS and REACH environmental requirements, continue to be developed to address the performance and reliability needs. With each new need, laminate material manufacturers go into the lab and see what new raw material can be used to improve resin system performance.

The process of developing a new resin system requires deep knowledge of how the PCB will be manufactured. PCB designers are most concerned with assembly process capability, long term reliability, thermal cycling performance, CAF resistance, and electrical performance, therefore, all these attributes must be balanced within the design of a resin system. The market requirements mean that laminate manufacturers must continue to research available options that will provide incremental improvements to the resin system performance.

Follow this link to download your copy of The Printed Circuit Designer’s Guide to… High Performance Materials.

01/26/2023 | Kris Moyer, IPC

In today’s ever-shrinking world of electronics designs, the use of BGA parts with very fine pitch features is becoming more prevalent. As these fine-pitch BGAs continue to increase in complexity and user I/O (number of balls), the difficulty of finding escape routes and fan-out patterns increases. Additionally, with the shrinking of silicon geometry leading to both smaller channel length and increased signal integrity issues, some of the traditional BGA escape routing techniques will require a revisit and/or adjustment to allow for not only successful fan-out, but also successful functioning of the circuitry of the BGA design.

01/25/2023 | Nolan Johnson, I-Connect007

Nolan Johnson recently met with Alun Morgan, technology ambassador at Ventec, and Ventec COO Mark Goodwin to discusses the industry’s determination to cling to outdated processes and standards, and some potential consequences. To maintain efficiency and keep pace with the market’s newest entries in Asia, Alun and Mark believe that legacy companies in the West must be open to challenging conversations that will require questioning old practices and revising those practices toward sustainability.

01/12/2023 | Patrick Crawford, IPC

Last year, IPC held its first-ever design competition at IPC APEX EXPO in San Diego. PCB designers from around the world competed in a series of heats during the months before the show, culminating in a showdown on the show floor between the top three finalists. Rafal Przeslawski, now with AMD, took home the top prize last year. This year, the competition is back for its sophomore year. I asked Patrick Crawford, manager of design standards and related programs for IPC, to “layout” the details on the design contest, including lessons learned in 2022 and what’s new for the 2023 competition.