Cannonballs, eBooks, and Signal Integrity


Reading time ( words)

Martyn_Gaudion_Interview.jpgStarkey: I did particularly enjoy the analogy that you've presented at a few conferences regarding this pile of cannonballs that you pass on your way to the office in the morning.

Gaudion: Yes (laughs).

Shaughnessy: How does that figure in? Tell us that story.

Gaudion: Well, the Huray method starting off was called the snowball method. The idea was that the dendrites on the copper looked like a messy pile of snowballs, but actually to get the dimensions and areas of the snowballs off an SEM is quite complicated and there's lots of different dimensions and work to do. So what Bert Simonovich said is, “If we made all the dimensions the same and actually piled them up like a stack of cannonballs, we could use one diameter and a certain base and use a cannonball stack method.”

I was actually driving on the way up to the office and there was a lovely big pile of cannonballs, and I took a photo on the way past, so I use that as the opening slide and I have this picture of cannonballs just stacked there, and people are thinking, "What's this about? I came here to learn about signal integrity, not about cannonballs."

Starkey: As you and I have said many times: All models are wrong, but some are useful.

Gaudion: And that's from a statistician called George E. P. Box, and again, some people think models are actually perfect but we all know that base materials are composite of glass fiber and resin systems and when they're pressed together the ratios of glass and resin change, and so you don't have an exact number on anything.

Starkey: And as a PCB fabricator, if you could achieve a good bond between metal and resin with a super smooth copper, it would make the signal integrity calculations much more straightforward.

Gaudion: It would, yes. We wouldn't make as much money on modeling!

Starkey: Yes, but you wouldn't assemble many multilayer boards because they'd all fall apart in the oven. Everything's got to be a realistic compromise, considering an awful lot of factors and parameters that go into making the finished product.

Gaudion: And that's an interesting point. I was saying that I’ve been speaking to automotive suppliers, but also, for the first time, chemistry suppliers are coming in saying, "Polar, we need to speak to you about roughness, because we're developing a new process that will give smoother copper and we'd like to analyze its impact on signal integrity." So we've started to speak to different people that historically Polar wouldn't really be involved with.

Starkey: I come from a process background myself, and I think the chemistry suppliers have responded very positively to the input that you've made.

Gaudion: That's good.

Starkey: Because as you say, you can specify a foil but then what does the fabricator do to that foil in process? When he buys a thin laminate, the foil that comes as part of the laminate has got known characteristics, with a degree of roughening on the side corresponding to the resin. Then subsequently he has got to make the other surface bondable, so he puts it through some sort of chemical roughening process to give a key for his laminating process. In the past it was something that didn't take into account any signal integrity consideration.

But largely as a consequence of the presentations that Martyn and Neil have done, the process guys now recognize the significance of it, and it's precipitated the development of a whole new range of bonding treatments that don't result in a surface that causes any further complication of the already complicated subject of maintaining signal integrity.

Shaughnessy: So if you're working with the chemical companies then, you'll be able to test their chemicals using impedance testing?

Gaudion: Or we'll give them the tools to test, yes. And certainly some of the laminate suppliers are now using our systems and software to qualify their new materials. It's a very interesting time to be in the industry at the moment and it's good that everyone's busy as well.

Shaughnessy: Somebody was telling me that if they have their boards built in China, that they use shops that have Speedstack. Because people who have no English skills whatsoever can still use Speedstack. It's handy across the language barrier.

Gaudion: We've done a lot of work in terms of many of our products being available in traditional Chinese, simplified Chinese, they're available in German, and they’re available in English -  we provide our tools in a number of different languages.

Shaughnessy: Is there anything that you want to talk about that we haven't covered yet? Anything you're working on, or anything you want to talk about in the future?

Gaudion: This year, in terms of signal integrity, we've added the signal integrity tools and incorporated them within Speedstack. We've got a very rich materials library database, about 17 different base material suppliers that are available online within Speedstack, and now you can generate a high-speed stack up and actually specify the insertion loss from within the stack up tool and provide all the graphs for insertion loss, along with the materials you're going to use, the number of layers, and all the information the supplier needs. So that's a big, big improvement.

But I always remind people that when you talk about materials, sometimes designers have a myth of a perfect material library that if they could spec the material perfectly they wouldn't need to speak to the PCB fabricator. But just recalling what Pete said, actually they still do. So it's important that we all keep talking with each other.

Shaughnessy: They’d rather not talk to anybody (laughs).

Gaudion: Yes, that would be my summary.

Shaughnessy: Thank you, Martyn.

Starkey: Yes, thanks very much indeed for your time Martyn. It’s been a very meaningful discussion.

Gaudion: Thank you.


Visit I-007eBooks to download your copies today:

The Printed Circuit Designer’s Guide to…Secrets of High-Speed PCBsPart 1

The Printed Circuit Designer’s Guide to…Secrets of High-Speed PCBsPart 2

Share


Suggested Items

Excerpt: The Printed Circuit Designer’s Guide to…Flex and Rigid-Flex Fundamentals

06/25/2018 | Dave Lackey and Anaya Vardya, American Standard Circuits
The design process is arguably the most important part of the flex circuit procurement process. The decisions made in the design process will have a lasting impact, for better or worse, throughout the manufacturing cycle. In advance of providing important details about the actual construction of the flex circuit, it is of value to provide some sort of understanding of the expected use environment for the finished product.

Mark Thompson: What Designers Need to Know about Fab

06/08/2018 | Dan Beaulieu, D.B. Management Group
Mark Thompson wants to help PCB designers. He’s seen it all in CAM support at Prototron Circuits: the incomplete or inaccurate data packages, boards that are unnecessarily complex or over-constrained, and so much more. Mark just returned to writing his popular Design007 Magazine column, The Bare (Board) Truth, which addresses questions such as, “What happens to your design at CAM?” I asked Mark to explain why it’s so important for designers to communicate with their fabricators, and why they need to get out of the office and visit a board shop every now and then.

Experts Discussion: What Does 5G Mean to Materials and EDA Tools?

06/06/2018 | Andy Shaughnessy, Design007 Magazine
Whether we’re ready for it or not, 5G technology is coming. We decided to speak with John Hendricks, market segment manager for wireless infrastructure at Rogers Corporation, and Ben Jordan, director of product and persona marketing for Altium, about the challenges related to 5G and what this means for PCB designers and fabricators.



Copyright © 2018 I-Connect007. All rights reserved.