Current Issue

A tech conference presentation spurs study of an exciting material option.

I like to ask designers about interesting projects or technologies they have worked on, and I heard from two designers, whom I met through my local PCEA chapter, about some very interesting and complex boards they designed using sintered copper. Both had used sintered Ormet Transient Liquid Phase Sintering Paste (TLPS) to design boards that would not have been possible otherwise. (There are a couple different vendors for sintered copper for vias, but I looked further into Ormet materials, as that was the material used in both the boards they told me about.) These boards were complex, with a lot of parts, limited space, RF signals with antennas and sensitive digital components, and I was told these boards would have been impossible to design without the sintered copper to create any-layer vias connections.

The Ormet paste provided a path forward to route, but this wasn't the first time I encountered this material. I first heard about it in 2014 from a fabricator that wanted to be able to document these types of vias in their stackup. In the past two years, however, I heard more and more requests for it from both designers and fabricators. What is it, and why has it taken so long to get traction in the PCB industry? This prompted me to put on my investigation cap and pursue some answers.

Read more: Sintered Copper Can Handle the Pressure

Models can reveal what design rules "forgot."

A picture is worth a thousand words, and that is especially true when evaluating the impact of changing trace dimensions in your printed circuit board.

The capabilities today of visualizing, in a matter of seconds, the complexity of the electromagnetic fields in one's printed circuit board are astounding. Twenty years ago, software tools to help designers make informed decisions were limited to numerical outputs or very rudimentary images. Often one required a significant level of understanding of the physics involved as well as a solid imagination to properly visualize the electromagnetic field lines and their significance. Even then, most visualizations were representations, not actually calculated fields displayed over the actual board and components. Many tools today provide unprecedented insights through such visualizations, equipping and enabling quick and intelligent decision making by designers on an unprecedented level.

I recall – and I hope you had a similar experience – a science class that used iron shavings and a magnet to make visible the once invisible magnetic fields as in FIGURE 1.

Read more: Changing PCB Trace Dimensions

Numbers on a data sheet are a good start, but confirm them with your own testing.

"Trust, but verify." While some readers will recall hearing this in the context of nuclear disarmament, I have it most notably drilled into my conscience by my first engineering manager while working in software quality assurance. And for good reason too! It was literally my role to verify the fixes that the engineers claimed they had implemented and to find the issues that were still open. While most of the time their fixes resolved the issue, sometimes it was only partially dispositioned.

So how do we successfully trust, but verify when it comes to information in data sheets for not just copper roughness, but other values significant for modeling signal integrity in printed circuit boards?

In a previous column, I discussed copper roughness and a partial story of the lifecycle of the copper as it moves along in the process of becoming part of a printed circuit board. In that article, I mentioned the dielectric constant/permittivity (Dk) and the dissipation factor/loss tangent (Df) of the resin/filler/glass combination. The data sheets used to be very secretive, with material suppliers concerned about corporate espionage regarding chemistries if the Dk and Df information was made publicly available. Depending on the material supplier and the materials in question, many times one can also find the construction data – glass weave style and quantity, resin content, and shelf thickness.

Read more: Models Can Be Deceiving: Trust, but Verify

System-driven part selection and routing are closer than ever.

it's rare for a motivational keynote speaker to have a lasting impact on attendees. At Zuken Innovation World's US iteration in June, however, Dan Thurmon certainly set the pace for the conference. The author of Off Balance on Purpose and a popular Ted Talk on embracing uncertainty, Thurmon's address had attendees referencing and even reenacting portions of his opening presentation in their subsequent presentations. The motivational speaker helped set an energetic and educational tone for the conference that followed.

And thanks to the coming AI revolution, uncertainty is what's ahead.

Zuken Innovation World is a series of conferences around the world dedicated to bringing customers, partners and Zuken experts together. A good portion of the eight concurrent training tracks at the June event in Scottsdale, AZ, was dedicated to sessions led by customer-users sharing design best practices and success stories. Surprisingly for a conference dedicated to a specific supplier, there was never even a hint of sales; this was a full-on conference dedicated to networking and educating, where one could learn about upcoming technologies, best practices, and novel implementations of toolsets that only a user would discover. At times, it was overwhelming to decide which of the concurrent sessions to attend, as multiple competing interesting presentations were occurring!

Read more: The AI Revolution is Coming to PCB Design

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