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\title{\textbf{Door Alarm}}
\author{Steak Electronics}
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  \section{PCBEast 2023}}
PCBEast 2023 was a three day conference and 1 day expo in Boxboro, MA. It was located at the Boxboro Regency Hotel, and was about 3 minutes from the intersection of route 2 and route 495. This expo was about 1 medium sized function room, so a smaller expo. There were about 4 aisles of maybe 12 companies each, so about 50 companies. Companies were global, but mostly US, with some from Asia and even less from the EU. The main company here was PCB Fabs, but there were a number of supporting businesses, and visiting an event like this is relevant for anyone who designs a PCB, not just fabs. Any EE might benefit from an event like this. 

I'm going to write up a bit on expos in my third book, so if you are interested in general expo advice (from someone who is a fan of visiting any type of expo) see that. This article is going to be a writeup of my notes from the expo. I typically write questions beforehand, and then visit each booth asking them my questions, branching off into new ideas as they come. So This list will show what I learned from the vendors I visited. Note that I didn't have time to visit all the vendors, as I procrastinated until the night before to write the questions by accident (haven't been to enough expos lately), so I only visited a selection of vendors. Here we go.


\section{Q & A Section}
I didn't actually visit the companies in this order as I started in the middle of the map, but I'll just write them down in order of my notes. And this section won't include the questions but will just be a writeup on each vendor.
\subsection{Accurate Circuit Engineering}
A fab. He mentioned copper coins as heatsinks on his website. Instead of using a traditional heatsink, he is using semi soft copper from Mcmaster Carr or Grainger, milled in a US xxxx Tools mill (can't read my notes - Sorry!). The copper coins are essentially a small cutout of copper. Instead of having a whole copper layer internally as a heatsink (which is possible) he uses the coins. Also the coins can go on the outer layers. They are very small, and don't really resemble heatsinks. See the photos. He prefers Rogers Cool Span epoxy to attach the coins to the board as this epoxy can cure in low temperatures or even in a vacuum. This is a conductive epoxy/heatsinking compound. It's possible to put the copper coins on inner layers (this will become more interesting later as we talk about embedding dies inbetween layers of a pcb...). The enig vs. electrolytic gold plating: Enig is typically 2-4 microinches, while elctrolytic can be as high as 50-100 micro inches. The enig can't get too thick or it will corrode a below layer.
\subsection{Polar Instruments}
Polar instruments makes a calculator type software (see their website) to help improve yield with high speed and inner layers of a PCB. I asked if there was a scripting interface available, but currently you would export from the program to Excel or XML and then act on that data. I'm not entirely sure if scripting is helpful for this software, but I suppose it can't hurt so it was the one question I had from looking at their website.

For an idea of what they do, see the Transline section of the PCB Calculator on KiCad and then consider what they software woould look like if this was a full fledged program. Obviously there is a lot of potential for improvement in Kicad, which really just introduces you to the concept. 

From my research beforehand, the need for software like this is to take high speed signals, and put them in a type of coaxial like trace on the circuit board. There are different ways to do this, but you could, like coax, put a dielectric layer, then a conductive ground around the signal, just in pcb form. The PCB is a component. Impedance is usually 40-120ohms (think 50 or 75ohms for radio or tv). Higher impedance is tougher to handle as the traces get smaller. Typically, 28,50,75, or 100 ohms.Differential wires \gt coaxial type wires.

You should also be aware that when pcb is etched in a subtractive process (pre-Ultra HDI) that the traces get a type of pyramidal shape when cut in a profile or cross section. This has effects on the signal as well. There is a good photo, and I'll include it in the git repo for this article (2023 git).

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