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You should almost always be dragging components by their origin, usually located in the middle of the part. Otherwise, components will no be aligned to the grid.
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General Guidelines
Below are some general placement guidelines. There are of course a bunch more, and we will mostly gloss over the “why” here but I do encourage you to ask a lead about them when you get the chance!
Rat's Nest
You may notice that there are a mess of lines between the component pads. These represent the connections that need to be made between pads according to your schematic. It might be messy at first, but use these to help you place components in such a way to minimize the number of connections that need to cross over each other!
Resistive Dividers
Resistive dividers should be placed close to the device which needs it, keeping the length of the “divided” net to a minimum. In the example schematic, the VBAT divider formed by R1 and R3 should be placed close to the op-amp U1 rather than the input connector.
Decoupling Capacitors
A decoupling capacitor is a device that supplies charge to an IC. These should be placed closed to the ground and power pins of the device as to minimize the “current loop”. Recall that current flows always in a closed loop. To visualize the size of the current loop, you can draw the path the current takes from the positive pin of the cap to the positive pin of the IC, through the chip to the gnd pin on the IC, and then to the gnd pin of the cap.
In this example, the current loop on the left is smaller than the one on the right! Realistically both of these are not too bad, at least the cap is next to the component.
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Connectors
When placing connectors, keep in mind that they are quite tall relative to other components, and are keyed on one side. This means there is a locking ramp that you have to push on to unlatch the connector, you can see this in the 3D view by pressing “3”. Make sure to leave space for your fingers!
For this reason, generally connectors are on the edge of a board with the lock facing outward. You should especially avoid placing connectors such that the lock is facing each other and very close together. It will be hard to get your finger between those connectors to unlatch them.
Board Shape
Now that you have completed placement, you can adjust the shape of the board to fit your components. Press “1” to enter the board outline edit mode, and go to Design → Edit Board Shape. You can then drag the edges to conform to your component placement. Remember that the origin should still be the bottom left corner of the board, so I suggest moving your components to there and shrinking the top and right edges. Board dimensions should be in full mm!
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