Reading the documentation for the AutoPopDelay
on MSDN (link) the maximum time you can delay a popup is 5000 milliseconds.
If you want a longer duration, use the Show
method to control the exact moment when the ToolTip is displayed.
...
However, I believe that you are trying to cure the symptoms and not the cause of your problem if you need a ToolTip to stay open for that long. A tool tip is, by definition, is "a small box with contextual information about the item the user to pointing to". If the user is unable to read what the tooltip is trying to suggest in 5 seconds, then it is not really a "tip" but an entire chapter from the help file.