When I first learned how to play “Hearts,” I was always worried about how to pass those three cards right off the bat. What if I helped who I was playing against? I got the hang of it eventually and with enough games under my belt. I could recognize card patterns to make the best choices, but until I got to that point it felt like I was throwing random cards across the tables.
My first circuit board designs weren’t too far off from my card strategy there, in particular with component placement. I hadn’t learned yet why certain parts had to go next to other parts, nor did I understand that I needed to use the schematic to help me make the best placement decisions. I would base my placement on where the guides were stretching to even if that wasn’t where the part really should go.
Over time though as my PCB design experiences increased my skills, I developed a good workflow for doing my parts placement. There are some important steps during placement such as floor planning and the order that you place the parts that can be a big help to you if you do them correctly.
Arrange Your Components and Floorplan Your Placement
In the same way that I organize my cards by suits in my hand, I have found that it really helps to arrange all of my parts according to where they need to be placed. I will do this in two steps with the first being floorplanning my placement. A floorplan is a sketched out plan of your parts placement before you start the actual task of putting components on the board.
Whether I create this floorplan myself or it comes from someone else, I have found that it’s a good idea to know where all the parts need to go before I start shotgunning components on the screen. This helps me to create a placement that allows for trace routing and an even power distribution.
After, I will bring my components onto the screen in logical groups from the schematic. Selecting the components by cross-probing from the schematic is especially helpful for this. I can select a group of components that are all tied together in a circuit, and place that group outside the board edge near the location where I know that they will eventually end up based on my floor plan.
PCB Layout Component Placement Guidelines
When you are playing hearts you will play certain anchor cards first to strategically accomplish tasks like drawing out the queen of spades. You’ll want to consider your strategy before moving into component placement, too, with some of these guidelines:
- Place your fixed anchor parts first: These parts will include anything that has to interface with the rest of the system that your board is going to be used in. Connectors, switches, speakers, lights, etc., are all examples of parts that must be placed in fixed locations in order to work with the rest of the system. Mechanical parts such as braces, nuts and bolts, and ejectors will also need to be placed in fixed locations.
- Segregation: Be mindful of the segregation that may be required when mixing analog and digital circuitry. Typically the analog section will need to be isolated from the digital by physical placement and routing that avoids introducing digital noise into the analog region. Other forms of segregation may be electrically isolated areas or high voltage sections that need to be carefully laid out to avoid unwanted interactions with other areas of the design.
- Place the main component circuitry: Once you’ve got the fixed components in place, you can begin with the main circuitry. Here is where that floorplan will really come in handy to give you a road map of all of your main circuitry.
- Place bypass caps and other related circuitry: These parts have to be placed in line and next to the components that they are connected to. For instance, resistors that are part of a transmission line can’t be placed clear over on the other side of the board. That would completely ruin the routing topology of the transmission line. Parts like these resistors need to be placed in the same way that the circuit is laid out in the schematic.
- Be mindful of signal and power routing needs: While it can be easy to get into component placement and forget about the routing needs that separate components require, it is important to keep these in mind to optimize the efficiency of your design.
- Check for potential EMI or thermal concerns: Heat, crosstalk, and interference can severely hamper your design’s capabilities.
- Optimise for manufacturing: Knowing the soldering and assembly process can provide advantages to give your design the best possible manufacturing yields. For example
Finalizing the Placement and Some Tricks that can Help You
Once your fixed components and the main circuitry is placed, you can finish up the placement with the rest of the peripheral components. Although these components are just as important, their placement won’t impact the critical routing topologies and you have more flexibility with their locations. This allows you to spread out their placement and give your design a little breathing room.
When you place your components, keep in mind that your PCB design tools have a lot of functionality built in to help you. There will be different placement utilities to use, as well as the ability to change the display in order to help you organize and place your board. Cross-probing between the schematic and the layout as I mentioned earlier is a very helpful resource to have at your disposal.
Consider using a grid. This helps both with the neatness of the board and helping to leave routing channels between components. Remember that for high density designs there will not always be room for all reference designators to fit on the silk screen. It is normally considered acceptable to skip designators where necessary and create an assembly drawing that fills in the missing information to help with manufacturer and fault finding.
Some useful tools in CircuitStudio are the move and align commands. These are a little bit hidden away on the Tools tab so you may not yet have noticed them.
Good luck with your designs and don't forget you can ask questions in our forums.
[Thanks to Altium for permission to reproduce this post]