Technically Appropriate Material Choices are Key to Design Success

Reading time ( words)

Materials are no longer a passive part of the design; they play an active role in the manufacturability, reliability, and speed of a PCB. I-Connect007’s Nolan Johnson and Mike Creeden, founder of San Diego PCB Design, discuss several key characteristics that designers should consider in their material selection process.

Nolan Johnson: Mike, could you introduce yourself and tell us about what you’re working on?

Mike Creeden: I’m the founder of San Diego PCB Design, and I had the opportunity to sell the company to Milwaukee Electronics/Screaming Circuits, so we’ve joined the Milwaukee Electronics family of companies. I also serve as an EPTAC instructor for the IPC CID and CID+ programs as an MIT (master instructor).

Johnson: We’re focusing on the latest developments in materials, and it’s important to get a designer’s perspective. Who do you see as being the leading companies in this segment?

Creeden: When I think of the different materials and products that are out there, one company comes to mind. So, I’m going to give some propers to Insulectro, which is a distributor for many of the major laminate material products that exist. I want to talk about them because there’s a difference between good and great companies. A great company is one willing to go outside of the norm, do something that helps the designer, and supports technology development.

Their main customers are fabricators, yet time and time again, I’ve seen them supporting designers by trying to enhance their technical knowledge and capabilities. San Diego PCB has been collaborating with Insulectro for several years now and is looking for ways to collaborate more. They’re helping us to design better, and we’re utilizing products in a timely manner as they’re helping us solve our customers’ problems. To me, Insulectro is a significant player in this electronics material industry.

Johnson: Could you give some examples regarding how they’re helping and contributing?

Creeden: Absolutely. When I’m challenged with real estate and cannot put the required capacitors on the board because I have BGAs on both sides of a board, the team at Insulectro is a resource I can go to and ask for technology help. They suggested buried capacitance materials, which helps my power delivery and filters out noise on the board. Another example is that we’re seeing a lot more rigid and rigid-flex circuits. Insulectro has coached us to utilize materials that are appropriate for these types of boards, which has helped us grow in our understanding of rigid-flex development.

Further, they point us toward their fabrication partners, which is their customer base, and this helps us understand both the material and process. There’s always a learning curve for designers when it comes to rigid and rigid-flex. Some of the Pyralux® materials that DuPont brings have also been useful for us trying to get our product right from the beginning. Additionally, I’m seeing more microcircuitry and some very fine features that pose a challenge. Some of the dry-film materials that DuPont offers help us with circuits that require accuracy in the definition of microfeatures.

Two of Insulectro’s product lines—DuPont and Isola—have some new, cutting-edge materials as well as products that we have utilized for a long time. With the technology advancement of today’s circuits, we need a product line that stays ahead of the curve. Some of the basic standards that we’ve been using for years, including FR408s and 370s, have been staples in our industry for so long because they are high-performance materials. But with newer, high-speed circuitry, you must consider the material as an integral of the performance of the circuit. Again, their support and coaching have made me a better designer and my customers have better performing products.

Johnson: What’s intriguing to me is that you’re talking about materials early in the process. You’re talking to materials experts as you’re trying to figure out the layout of the board. When in the design cycle should PCB development people consider material selection?

Creeden: That’s a great question. It should be within the first days of starting your project because that’s the best time to establish that things will be designed “correct by construction.” I do not want to design a product and then consult my fabricator in the last days of development. If the material is not in stock, we may be delaying the procurement of what is probably a late design, anyway. You’d want to make sure that it’s in stock, and you’d also want the coaching from your fabricator and supply chain to make sure that you’re making correct selections. When you do this late in the process, selections may happen quickly, and there may not be enough time to ensure that it’s an appropriate material selection. There’s always a material technology decision, and it should be made early in the design process. The earlier, the better because this allows time to change it if that is required.



Suggested Items

Stitching Capacitor: Crosstalk Mitigation for Return Path Discontinuity

06/13/2019 | Chang Fei Yee, Keysight Technologies
When the return path is broken due to the switching of reference planes with different potential, e.g., from ground to power or vice versa after layer transition on PCB, the return current might detour and propagate on a longer path, which causes a rise in loop inductance. This might lead to the sharing of a common return path by different signals that pose a high risk of interference among the signals due to higher mutual inductance. This interference results in signal crosstalk. To mitigate the crosstalk due to return path discontinuity (RPD), stitching capacitors are mounted on the PCB to serve as a bridge between the two reference planes of interest on different PCB layers.

EM Modeling: The Impact of Copper Ground Pour on Loss and Impedance

05/02/2019 | Chang Fei Yee, Keysight Technologies
This article briefly introduces the general purposes of copper ground pour on printed circuit boards. Subsequently, the impact of copper ground pour on PCB channel loss in terms of insertion loss and impedance in terms of time domain reflectometry (TDR) is studied with electromagnetic modeling using Mentor HyperLynx.

3DEM Modeling: Influence of Metal Plating on PCB Channel Loss and Impedance

03/21/2019 | Chang Fei Yee, Keysight Technologies
This article briefly introduces different types of metal plating commonly used in PCB fabrication. Subsequently, the influence of metal plating on PCB channel loss (i.e., insertion loss or S21) and impedance (i.e., time domain reflectometry or TDR) is studied with 3DEM modeling,

Copyright © 2019 I-Connect007. All rights reserved.