-
- News
- Books
Featured Books
- design007 Magazine
Latest Issues
Current IssueLearning to Speak ‘Fab’
Our expert contributors clear up many of the miscommunication problems between PCB designers and their fab and assembly stakeholders. As you will see, a little extra planning early in the design cycle can go a long way toward maintaining open lines of communication with the fab and assembly folks.
Training New Designers
Where will we find the next generation of PCB designers and design engineers? Once we locate them, how will we train and educate them? What will PCB designers of the future need to master to deal with tomorrow’s technology?
The Designer of the Future
Our expert contributors peer into their crystal balls and offer their thoughts on the designers and design engineers of tomorrow, and what their jobs will look like.
- Articles
- Columns
Search Console
- Links
- Media kit
||| MENU - design007 Magazine
Brooks' Bits: How Many Vias Does It Take To…?
May 4, 2016 | Douglas G. BrooksEstimated reading time: 2 minutes

Sounds like the opening words of a bad joke. Well, here’s the answer, and it’s no joke: One! That’s right. No matter how much current you are putting down the trace, all you need is a single via. And a small one, at that.
OK, that last statement might not be true in EVERY single case. But it is true in a LOT more cases than you think. I will explain why in this column.
During 2015, I enjoyed a very productive collaboration with Dr. Johannes Adam, from Leimen, Germany. That collaboration resulted in several papers, but one in particular is relevant for this column, “Via Currents and Temperatures.” In that paper, we used a simulation tool, thermal risk management (TRM), developed by Dr. Adam, to simulate current flowing through a via and then determine the temperature of the via. The conventional wisdom is that the conducting cross-sectional area of the via should be the same as (or greater than) the cross-sectional area of the trace (conductor.) IPC 2152 explicitly endorses this:
The cross-sectional area of a via should have at least the same cross-sectional area as the conductor or be larger than the conductor coming into it. If the via has less cross-sectional area than the conductor, then multiple vias can be used to maintain the same cross-sectional area as the conductor.
But our results contradicted this; they suggested that the temperature of the via was controlled by the trace, and as long as the trace was sized correctly, any old (single) via was good enough.
If there was ever a result that cried out “show me,” this was it.
So I set out on a path to build a test board, test it, and verify the simulation results. This type of study would not have been possible without the cooperation of several people and organizations. In particular, I want to thank my longtime partner Dave Graves (now with Monsoon Solutions in Bellevue, Washington) for helping prepare the final artwork for the test board. C-Therm Technologies (Fredericton, New Brunswick) graciously measured the thermal conductivity of the board material to facilitate the simulation. And a special thanks to Prototron Circuits of Redmond, Washington, who provided the test boards and also the microsectioning work and measurements. And my collaborator on trace thermal issues, Johannes Adam, continues to be a great help in evaluating results.
Figure 1 illustrates the relevant portion of the test board. There are two 0.5 oz. test traces, each six inches long, each consisting of two, three-inch segments (top and bottom) connected by a single 10 mil diameter via. The via is plated to approximately one ounce. One test trace is 27 mil wide, providing approximately the same cross-sectional area as the conducting area of the via. The other trace is 200 mil wide. It is important to note that the vias are identical for the two traces.
To read this entire article, which appeared in the March 2016 issue of The PCB Design Magazine, click here.
Suggested Items
Statement from IPC on ‘Liberation Day’ Pressing for Domestic Manufacturing Strategy
04/03/2025 | IPCIPC, a global electronics association dedicated to furthering the competitive excellence and financial success of more than 3,200 members, shared the following statement today on U.S. tariffs and their implications on the global electronics industry. It can be attributed to Richard Cappetto, IPC senior director of North American government affairs:
My Top 10 Highlights from IPC APEX EXPO 2025
04/03/2025 | Chris Mitchell, IPC VP, Global Government RelationsEvery year, I am reminded what an exciting and fast-paced whirlwind IPC APEX EXPO is—the friends you run into, the new people you meet, the innovations you encounter, and the fascinating discussions you dive into. It’s certainly true that our industry is driven by searchers and problem-solvers, creating endless opportunities at APEX EXPO to connect, collaborate, and shape the future.
Winners of 2025 IPC Masters Competition China Announced
04/02/2025 | IPCOn March 26-28, the IPC Masters Competition China was successfully held in Pudong, Shanghai. This year’s competition brought nearly 500 electronics industry elites from 18 provinces and municipalities.
IPC APEX EXPO 2025 Review: Shifting My Focus to the Show Floor
04/02/2025 | John Watson, CIDIPC APEX EXPO 2025 marked a significant milestone as it celebrated its 25th anniversary. (Personally, I don’t think it looked a day over 20.) If you didn’t attend this great event, why not? This was my 10th anniversary of attending, and it had a distinctly different feel. There was a celebratory atmosphere as both veterans, like myself, and first-time attendees, were drawn into a celebratory occasion marking the significant milestone of the 25th anniversary.
Real Time with... IPC APEX EXPO 2025: Advanced Silicone Solutions from CHT
04/02/2025 | Real Time with...IPC APEX EXPOCHT team members introduce themselves and share their roles, with Kate Sincerbox focusing on technical service and Lisa Stutzman on inside sales. CHT specializes in silicone materials for encapsulation, adhesives, and coatings, serving the automotive and aerospace sectors.