There are a number of considerations an experienced PCB designer applies for thermal management. However, the key design steps essential for effectively dissipating heat are:
- Properly distributing analog circuitry throughout the board.
- Effectively using ground pour on the PCB.
- Strategically deploying thieving, when possible.
- Considering a metal core (MC) board, if applicable.
- Creating more solid planes for transfer of heat.
- Selecting the proper heat sinks and attachment process.
- Using thermally conductive grease when applicable.
The experienced PCB layout engineer is extremely valuable for designing circuitry so it can effectively dissipate generated heat. This is especially true for PCBs loaded with analog circuitry. First off, he or she distributes analog circuits on the board so there is no thermal concentration in a particular area.
If the circuitry allows it, the next step is to perform so-called “ground pour.” This involves pouring copper on the PCB’s unused surface area. Basically, the PCB designer is spreading copper over the surface area through which heat can be dissipated. So, instead of using one small surface mount (SM) pad for heat dissipation, the PCB designer is now increasing the surface of the board, for example, to a half-inch by half-inch pour surface area. This ground pour area then dissipates the heat a lot more quickly compared to the SM pad alone, Fig. 1.
For a more detailed account of PCB thermal management, read our article.
The OEM customer should also take into consideration “thermally-friendly packages” that component manufacturers produce. Basically, what they’re doing is building up packaging laminates to increase thermal performance superiority.
For example, a BGA may have two, four, or six laminate layers. These multi-layer laminates contain internal ground planes connected to thermal vias under the silicon die. In effect, component manufacturers are helping to dissipate the heat before it even goes further into a board.
A TO72 package is another good example of how packaging can increase heat dissipation. An alloy used as a heat sink is utilized here to dissipate the heat directly off the body of the component. However, in most cases, even with these packaging advances, thermal management continues to be challenging. It’s always best to work with EMS providers that have a solid handle on and experience with thermal management.