The secret for carbide is a drill setup with minimum run-out, no give,
and no wobble.
I have an old-style Dremel drill stand that holds the tool steady, and
lifts the
table up and down, like a "knee mill." That works well.
The later Dremel drill stands move the tool up and down to drill
holes. The Dremel shifts slightly
as you lower it into the workpiece, snapping the bit.
Dremels aren't perfect, but if the bearings are reasonably tight
they'll get the job done.
I've had few to no problems*. You want to run them as fast spindle
speed as possible. They cut FR4 like butta. I don't often drill much
less than 0.8mm (0.031"), which is pretty sturdy- if you're trying to
drill 0.015" holes, things might be dicier.
* A few weeks ago I reached into one of the ubiquitous little boxes of
resharpened carbide bits by mistake and about 8mm of tiny via-size bit
punctured my finger and broke off in the finger. Ouch. This was after
breaking a 1/4-20 tap off in a part, so I was grumpy to start with
(took a couple hours to salvage the part). I thought a cheap "set of
taps" would be okay at that huge size- I was wrong- bought some good
quality ones (Chinese, but top-notch stuff) and no more problems. The
cheap-a** 4-40 die wouldn't even thread onto a proper sized brass
turning. Criminally bad "tool shaped" garbage- ultra brittle, dull,
and not the right dimensions.
Moral.. don't go cheap on cutting tools!