Strategy to use for placing components?

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hey guys, Can anyone share strategy to use for placing components at its best before proceed to routing?
I am just confused between two things that
1)should we have to place component individually one by one and do parallel routing accordingly
OR
2) should we have to arrange all the components then proceed for routing
which is more effective??

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For me it’s an iterative process. I try to work out the best placement for the major components, and watch what happens to the rats nest. I may move or rotate components. Then I hit some constraint and I may have to try a different layout. Often I go away and think about the problem and come back with a new idea. Sometimes I even modify the circuit. E.g. no space for transistors? Use an array IC. THT resistors taking up too much space? Use a network resistor. GPIO pins not in the right area? In these days of flexible assignment of functions to pins you can even change this with software. So the iteration reaches into the firmware also.

Fortunately I’m not under time pressure to produce a result.

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oh great.
Thanks for sharing your strategy @kenyapcomau .Really helpful for me.

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I tend to group things up by the least external connections, e.g. for a given chip, I group all the components that connect to only it, right next to that chip on a seperate area of the PCB and move them around until the lest number of traces would have to cross and it fits any other requirements,

I then take those groups and move them around each other until again most of the traces do not need to cross, and the connections are short or releativly easy

I generally pair this with actually routing, but the same priciples apply

Start will small functional groups, then group them up into functional blocks, then arrange them to make up your design,

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This is probably roughly the same as has been said before…

Whether you design the schematic in one sheet or use hierarchical sheets, you should usually group the components functionally in the schematic. Connectors have their TVS components, regulators have their capacitors and tuning components etc.

Usually your board will have some interface to the outside world: connectors, display, buttons etc. Try to find out some rough outline design for the board and placement for those interface components.

If you don’t have any need to limit the size of the board, don’t limit it too much. Usually the needed space and the space taken by the components+connections are underestimated.

Put the main components in their rough places, leaving plenty of room. Gather each main component’s “helper” components around their main component (or move each ready made group to their places - you can do several smaller blocks first and move them afterwards).

Draw the most important traces first. High currents and high speed signals are important.

Move and rotate individual components or groups iteratively, and draw tracks, refine them and delete and redraw them iteratively.

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thank you for sharing your strategy @Rerouter

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thank you for sharing your strategy @eelik

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If possible, especially for beginners, if you can design your board in sections start playing with the routing and placement as you go. Don’t wait to finish the complete design.

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I’m not the most experienced person but I worked out my strategy over the years of doing 2 layer boards of various complexity:

  1. Consider the edge outline constraints, if any. For example if you already have an enclosure, draw a board that will fit perfectly inside. If it ends up too big you can trim it later but it’s much harder to redo whole board if you find out in the end that it doesn’t fit where it should.
    This includes mounting holes.
  2. If there are no such constraints (enclosure is known to be big enough and mounting holes can be adjusted as needed or another mounting method will be used) then go for simple rectangular shape that will be easy to work with. It takes some experience to know how big of a rectangle you need when all you have at first is a bunch of components randomly spread out in the board editor.
    I personally like to make it a bit smaller than what seems to be needed as that pushes me to make tighter routing and usually I still have space left over because placing components on both sides allows for efficient use of the surface.
  3. Place all large components and components that need to be in specific spaces first. I.e. displays, buttons, switches, connectors, trimpots. Anything that will affect ergonomics and usability, think about it in this step. You can make small adjustments later but I never allow for buttons to not be neatly in a row or for connectors to be difficult to access because they are in the middle of the board.
  4. Next place the MCU or any other components with large amount of pins. Continue to smaller parts and last passives. Rotate and flip around to have a ratsnest with least crossings. Don’t forget that flipped parts can “overlap” parts on the other side, they are not sharing the same space.
    This stage is probably the most important, effort you put here will make routing a lot easier.
  5. When you are happy with initial placement start with routing important traces first: transmission lines, diff pairs, buses, interfaces. Then do the rest. Adjust placement as needed to make routing cleaner or easier. There is a lot of nuance here but this topic is about placement.
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