Julie Ellis: TTM’s Interface Between Designer and Fabricator

Estimated reading time: 12 minutes

As a field application engineer for TTM, Julie Ellis sees the problems that can occur between circuit board designers and manufacturers. I spoke with Julie at the AltiumLive event in Munich about the age-old problem of throwing designs “over the wall,” the trend towards HDI, and what advice she would give new designers.

Barry Matties: Julie, as a field applications engineer, you act as the liaison between the fabrication team and the design team primarily, correct?

Julie Ellis: Yes. And sometimes contract manufacturers when they're buying and building and assembling boards for my customers.

Matties: You're in a unique position to see the challenges and the successes and the frustrations and those sorts of things. Can you tell me about your background?

Ellis: I started in engineering at the University of Iowa and followed a boyfriend to California when I was 20. As I was finishing up school at California State University, Fullerton, I was lucky enough to be awarded a student engineering position at Hughes Aircraft. After graduation, I stayed on with Hughes as a design engineer for another five years. Then I left Hughes and went into technical sales and support.

Matties: Then you landed at TTM?

Ellis: Actually, I did a lot in between, because I was a manufacturer's rep for semiconductors, and then we picked up a board line and I really liked the circuit board side. From there, I moved to represent Nan Ya Printed Circuit Board Corporation in the U.S. for the nephew of the founder of Nan Ya out of Taiwan. When Nan Ya started pulling out of the rigid printed board business in the United States and began supporting substrates for the chips instead, I went into contract manufacturing for a small company, moved around a little bit and then literally begged for this FAE position at TTM when it opened up.

Matties: How long have you been with TTM?

Ellis: Three and a half years.

Matties: Tell us about that role. What's your typical day like?

Ellis: I check my emails at 6 am, to see what came in from China. I try to send everything out to customers, like technical queries after we've done DFMs on new parts coming in, early. Then I aspire to go outside to feed our horses and start my official work day by 8 am, but my boyfriend gets stuck doing it most of the time because work is so demanding. Between supporting new standard designs, investigating science project designs, supporting assembly issues and being “PCB problem solver,” and then starting up with China after dinner, it's typical for me to work very long hours.

Matties: What kind of horses do you have?

Ellis: Thoroughbreds and Appaloosas.

Matties: Racing?

Ellis: Ex-racing. One was a lousy racer. She was so slow that her breeders never raced her. And another one started getting injured tendons at the racetrack and the owners needed to dump him. I’ve rescued and rehabilitated several injured ex-racehorses, as well as a couple others in need.

Matties: So, from horses to circuit boards, you've got it covered.

Ellis: I do have it covered, yes.

Matties: Let's talk about circuit boards. What are some of the most common problems that you see?

Ellis: First, fab drawing dimensions that don’t match Gerber dimensions and other data conflicts. Second, tight mechanical tolerances that are not supported by standard material and equipment. And third, thermal via-in-pad designs that are not properly protected to prevent solder from going down the holes. Plugging them with solder mask is the low-cost solution, but the plug depth is variable. Non-conductive epoxy fill completely fills the holes and can be copper-plated to solder to.  Optical routing and via filling require special equipment and take more time, so they add cost.

Matties: Are the designers that cost-sensitive?

Ellis: Customers have to be competitive, so yes, absolutely.

Matties: When they're not willing to pay the extra that causes extra work on your end, how do you mitigate that?

Ellis: Sometimes I have to draw pictures of min and max conditions, so everyone understands what the final product they’re committing to will look like to their receiving inspector. That way, they can approve it as-is.

Matties: Here at the AltiumLive conference, after the designers speak, and it comes to the Q&A session, people have a lot of really good questions, but they're challenging, in some regard. What is it like to deal with designers in this arena and challenge the existing paradigms?

Ellis: Usually it's good. If I explain what happens in our process, or to the material, so they can understand why paradigms are challenged, they can often work with me.

Matties: I've done a lot of interviews, and one of the common themes that I frequently hear is, "Designers need to understand the manufacturing process." And then on the other side of that argument people are saying, "No, they don't need to understand the manufacturing process with deep knowledge; what they need is better feedback from the manufacturers." I've heard that as recently as one hour ago. How many times do designers request feedback from a completed project?

Ellis: I estimate designers request a preliminary DFM on 5% of PCBs purchased by my customers before they release their final documentation. Designers normally end up receiving feedback on their completed project before fabrication begins whether they want it or not, because design violations that can’t be processed, and data conflicts found during our CAM process, will be returned to them in a technical queries (TQ) form. "We request approval to remove the solder mask dams between pads on components U22 and U25 because there is not enough distance between them" is a typical example.

Matties: There's a large window of acceptability and it may not be a manufacturing issue, but there may be a strategy, or if they changed an approach that they could really improve their product.

Ellis: Strategy planning is most effective at initiation of a new design. That's why I always try to ask my customers to engage with TTM at the beginning of a design, so I can get an idea of what they're looking for and what their requirements are. Then I can propose the most cost-effective, reliable solution, including stack-up, pad stack, and design guidelines before they begin routing.

Matties: It’s great that you provide that service, but often times I hear that the designers throw the design over the wall. "Here you go; build what I asked for." And at that point it's too late, but if they're in that window of acceptability, how do they improve if there's not a proactive feedback loop and if they don't take the time, which could be a lot of time, to really understand the PCB manufacturing process?

Ellis: Busy designers can still request and use suppliers’ DFM guidelines for lines/spaces, aspect ratio, min. drill size, min drill-to-Cu, min Cu to fab line, dimensional tolerances, etc. I’ve been very fortunate with my on-going TTM customers, who generally appreciate and utilize up-front design guidelines and stack-up support.

Matties: Maybe you are the exception, because I hear this so often.

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