At what point will I start having trouble with noise and parasitic capacitance/inductance when using standard 0.1in header pins? If I'm using an MCU capable of driving a 20MHz SPI bus, would it be reasonable to run a breakout board or Arduino shield at that speed? I will be using either the ST NUCLEO-F446RE or the NUCLEO-F303K8 development board.
Electronic – Header frequency limit
headernoiseparasitic-capacitance
Best Answer
There is no such thing as a "maximum frequency" for the header itself, unless the wavelength becomes comparable to the total pin length and you need to treat it as a transmission line. This can be a serious issue at 100MHz with a 2-meter long coax cable, but with a sub-10mm connector, you must be talking obscene speeds. You will probably have much more than 10mm of traces on the main board and the breakout board.
I have used breakout boards for prototyping a few times, with an expensive chip on the breakout which I cannot desolder easily. Here is what you can do: