I have a PCB that is having signal integrity issues. This is a four-layer board, the top and bottom layer is signals and power and the inner two layers is a solid ground plane with no breaks in it.
My SMPS seems to causing the PCB FR4 material to heat up to around 65 degrees Celsius (when it is loaded.) If I touch anywhere on the PCB it causes one of the data lines to invert its signal. Sometimes even binding a THT electrolytic capacitor to lay directly on the board causes issues.
When the PCB is not loaded, I have no signal integrity, even if I touch the PCB or lay the capacitir on the board.
Does heat (in this case at 65 degrees Celsius) cause signal integrity issues? How does it cause it and what can I do to solve this issue?
N.B This PCB is heatsinked through an aluminum enclosure.