# Douglas Brooks

Douglas Brooks has a BS/EE and an MS/EE from Stanford and a PhD from the University of Washington. For the last 27 years he has owned a small engineering service firm and written numerous technical articles on printed circuit board design and signal integrity issues, and has published two books on these topics. He recently published PCB Trace and Via Temperatures: The Complete Analysis, 2nd Edition, with Johannes Adam in 2017.

Brooks has given seminars several times a year all over the US, as well as Moscow, China, Taiwan, Japan, Israel, and Canada. His primary focus has been on making complex technical issues easily understood by those without advanced degrees. Brooks is now retired and lives with his wife of over 50 years in Issaquah, WA. His Web page is https://www.ultracad.com.

## PCB Signal Traces Are Hotter Than We Think

In this article, Douglas Brooks and Johannes Adam illustrate how the thermal impacts of heated traces and pads are not limited to the board layer on which they exist; read on to see how they are reflected on every board layer above and below them.

## How Do Traces Fuse (Melt)?

What happens when you apply current to a trace? How long until disaster ensues? Douglas Brooks and Johannes Adam melted some boards, turned traces into flames, and applied some equations to shed some light on these questions.

## Internal Trace Temperatures; More Complicated Than We Think

It turns out that dielectrics, in fact, cool traces more efficiently than does convection + radiation, and therefore internal traces are relatively cooler. In this article, Brooks & Adam examine the question: Is there a predictable relationship between the external temperature of a trace and the internal temperature of the same trace carrying the same current?

## Current Density: Interesting, But Irrelevant

Current density can be an interesting concept. Graphics based on current density can be fascinating. But from a practical standpoint, current density is irrelevant. It is a consequence of other things, not a determinant of them. What follows will explain why.

## Vias Are Cooler Than We Think

The inescapable conclusion from the analysis presented here is that the conventional wisdom has been wrong! The current does not determine the temperature of the via. Find out what does.