Issue link: https://iconnect007.uberflip.com/i/652863
44 The PCB Design Magazine • March 2016 board. C-Therm Technologies [5] (Fredericton, New Brunswick) graciously measured the ther- mal conductivity of the board material to fa- cilitate the simulation. And a special thanks to Prototron Circuits [6] of Redmond, Washington, who provided the test boards and also the mi- crosectioning work and measurements. And my collaborator on trace thermal issues, Johannes Adam, continues to be a great help in evaluat- ing 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) con- nected 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. A controlled current was applied to the trac- es (8.55 A to the 200 mil trace and 6.65 A to the 27 mil-wide trace) and the temperatures along hoW many Vias does it take to…? Figure 1: The relevant portion of the via test board. Table 1: Summary of test results.