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40 The PCB Magazine • December 2017 Conclusion Thermal cooling at the PCB level is always an option as there are various configurations of finned or bladed heatsinks that set onto a de- vice which then carries the temperature out of a specific location. Open any desktop system and you will still see this used today on the moth- er board. Again, however, the area needed for the finned heatsink to draw upward and away from the PCB board uses volumes of space (and weight). In the case of this article we are focusing on what the options are for thermal management considerations at the bare PCB level but there are many options open that can be used to re- move heat from a device, a location or from the PCB itself. Designers must consider all the options when choosing one method over the next, or even when combining which methods they are considering. One important thing to consider when cre- ating a thermally conductive bare board is how this will affect the assembly portion of the build cycle. If a PCB has great thermal absorption, that will affect the soldering process. An example of this might be to have your thermal zone(s) too close to a device that is sensitive to heat which can be damaged during the soldering process due to the potentially increased amount of heat needed to make a solder joint. There are many options for the PCB design- er to choose from. It is not uncommon to see many designs that combine one or more of the heat removal methods discussed above. An ex- ample of this would looking at today's RF de- signs, as they commonly use mixed materials, cavities and coins all within the same structure. Today the industry is building many types of structures, adding even more elements of en- hanced design uniqueness. One of these new technologies, called "air cavity," is something that we see which adds great value for advanc- ing thermal mitigation for the demanding needs of tomorrow's products. Stay tuned as we move forward… Acknowledgement The author would like to acknowledge and thank CTO Yaad Eliya and Technical Expert Shlomi Danino, Sr., both at PCB Technologies Ltd, for their valued input to this article. PCB Jim Barry is the solutions architect for PCB Technologies Ltd (Israel) and supports the North American market. He has nearly 40 years of engineering, manufacturing and application experience within the PCB/PCBA industry. To contact Barry, click here. THERMAL MANAGEMENT CONSIDERATIONS AT THE BARE BOARD LEVEL Figure 6: Cross-sectional view of coin technology options.