In researching whether or not it's common practice to run traces/place vias underneath electrolytic capacitors (specifically SMD electrolytics, didn't seem like it would be an issue to me), I came across this document which makes some statements about electrolytic capacitors that conflict with with other information I've found.
First: "For circuits where the polarity is occasionally reversed, use a bi-polar type of aluminum electrolytic capacitor. However, note that even bi-polar type capacitors must not be used for AC circuits."
I thought one purpose of using bipolar electrolytics is where high capacitances are required in AC circuits.
Then: "Do not print any copper trace under the seal (terminal) side of a capacitor. Copper traces should be 1 mm (preferably 2mm or more) spaced apart from the side of the capacitor body.
· In designing a double-sided PC board, do not locate any
through-hole via or unnecessary hole underneath a capacitor.
· In designing a double-sided PC board, do not print any
circuit pattern underneath a capacitor."
On every board I've seen with leaked electrolytic capacitors, the electrolyte leaked much further out than just 1mm from the capacitor body. I get that maybe in the ideal case it would be best not to route traces under caps in case they fail and leak, but is this practice commonly adhered to? Is it really a bad idea to route traces/via under caps?
What is your take on the above statements?