Ignoramus32423 fired this volley in
:

Lloyd, I used those holes to mount TO-220 voltage regulator chips, not
for anything structural. worked great!

They won't hold with temperature swings, Ig! Put a nut and lockwasher on
the backside! Go with me on this... I've done many THOUSANDS of
semiconductors on heatsinks, and had both many successes, and every sort of
failure you could count -- from taking shortcuts. Shortcuts just never
work in a temperature-cycling environment.

Lloyd