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First, we asked you to send in your questions for Happy Holden, Joe Fjelstad, John Mitchell, and others in our “Just Ask” series. Now, it’s Tara Dunn’s turn! Tara is the vice president of marketing and business development for Averatek. A regular Flex007 columnist, Tara discusses flexible circuits, rigid-flex, and rigid PCBs, as well as RF/microwave technology, microelectronics, and additive processes. She is also co-founder of Geek-a-Palooza and a show manager for the SMTA Additive Electronics TechXchange event. She has over 20 years of experience in the PCB industry. We hope you enjoy “Just Ask Tara.”
Q: What is the maximum thickness of a single flex layer, not just for a test vehicle but a flexible circuit layer manufactured commercially?
A: There are a lot of different ways to answer this question. There are examples of flexible circuits being manufactured with 10-ounce copper bonded to dielectric. In this case, the “body” of the flexible circuit is typically etched to a thinner copper for flexibility and leaves the contact fingers with the thicker copper.
Looking at what laminate thickness are commercially available for fabricators, Dupont provides a laminate with 0.005” dielectric, bonded on each side to four-ounce copper, with 0.003” adhesive. That is an extremely thick laminate, at 0.0222”. The most common flexible laminates are much thinner, with half-ounce or one-ounce copper bonded to 0.001” or 0.002” polyimide, resulting in thicknesses of 0.0024–0.0068”, depending on adhesive requirements, dielectric thicknesses, and copper weight.
To submit your questions for Tara, click here.
Check out Tara's column here.
Cody Stetzel, Cadence Design Systems
I have the tendency to try to replicate the delicacies I’ve ordered at restaurants in my own kitchen. One of my latest attempts at creating restaurant-worthy dishes was a Korean pancake that’s crispy on the outside but soft on the inside. With my amateur cooking skills, it proved to be an impossible task—I could either make only a hard pancake or one that was total fluff. While I’m still struggling to figure out the trick to bringing together the different textures of a Korean pancake, I’ve had more success in bringing together the hardboard elements and flexible PCB elements of a rigid-flex PCB. Compared to making Korean pancakes, striking the right balance of flexibility and rigidity on a rigid-flex PCB is easy if you abide by rigid-flex PCB design guidelines.
Nolan Johnson, I-Connect007
I recently spoke with Jamin Taylor, vice president of sales and marketing at All Flex Flexible Circuits in Minnesota. We discussed the company’s recent merger with Printed Circuits Inc., and some creative new flex applications, including flexible heaters and catheters for the medical field. As Jamin explains, "It’s always interesting to see different technologies amongst different companies. We’re working on a few new applications and products, like being able to do some fine lines and flex materials, but with large format, a longer format than usual. Some of their capabilities with lasering and fine features really help with our long flex capability; when we merge the two, we see a new market being created for that technology."
Pete Starkey, I-Connect007
For the first time since its foundation in 1974, the Institute of Circuit Technology had no alternative than to conduct its Annual General Meeting online. The event, which took place on February 25, 2021, was remarkably well-attended, and was followed, as is traditional, by a technical seminar. The seminar became a webinar focused on novel materials and methods for printed circuit fabrication and moderated by ICT Chair Emma Hudson.