Phenolic machines much like plexiglass. It is very brittle and heats up easily. It's best to use a scraping cut at slow speed and use a scrap stock backer to prevent blowout. You can use a regular drill bit, but grind a small vertical flat on the end of each flute instead of sharpening it, so that it scrapes the hole rather than biting in and cutting it. Then run the drill slow enough that you don't get any melting. It will make a perfect hole. An alternative is to use glass cutting bits, which have flat, hard blades shaped to a curved point that scrape rather than cut, but again, run them slow enough not to melt the material.
Putting a flat grind on a regular twist drill bit is a trick that I found for drilling laminate counter tops to keep from chipping the laminate around the hole.
Central North Carolina