what drill bit for alumina?

[coppercone2]

What drill bit should I use to drill small holes in a alumina PCB ? Or possibly AlN too.

I wanted 0.5 or 0.7mm holes for RF vias for copper plating experiments.

A diamond drill is the best for this job? What manufacturer should I be looking at for this?

[jpanhalt]

According to PCBOnline, it is laser drilled.

[coppercone2]

they can sure do that in a factory but I am looking for a premium small diameter drill bit. plenty exist but my experience with Chinese diamond tools shows me their life is very short. In most cases when I switched to brand name drills of any kind they were superior, but I don't know where to look, I am not convinced websites are just selling chinese junk for premium (jewelry)

[jpanhalt]

My experience with glass and ceramics is that it must be done with good water cooling.  Diamond would probably work.  I suspect it will be more of a grinding than cutting action.  I have never worked with solid alumina as you have.  Are the corundum gemstones drilled?  Google AI says yes, with diamond and water.

[mendip_discovery]

I would look at getting some reamers. They are designed for making precise holes. A drill bit hole is looked at closely is more of a triangle than round. A reamer is 5 flutes and often are tapered and will just finish off the hole and make it just right.

[tooki]

I would look at getting some reamers. They are designed for making precise holes. A drill bit hole is looked at closely is more of a triangle than round. A reamer is 5 flutes and often are tapered and will just finish off the hole and make it just right.

Sorry… reaming alumina?!?

Not aluminum. Alumina, i.e. aluminum oxide, which is so hard it’s commonly used as an abrasive.

A drill for this is actually just a diamond grinder.

[coppercone2]

small reamers are none the less of interest to me I see they cost 60$ a piece for a VIA sized carbide reamer for fiberglass substrates

I think a sintered drill is what I am looking for, electroplated drills may work but you need to get a good one, that is multi layer diamond plated... I see none of this is cheap. I can't find brazed drills in a size smaller then 1/8 for diamonds.


I see "swiss made" diamond drills but it does not tell you how many layers of plated diamonds there are. sintered drills look more like stone burrs but it might be the most durable one, however the RPM requirements are 10x of my capacity, perhaps on a dremel instead of sensitive drill press.

[jpanhalt]

Sintered what?  If a typical grinding stone (e.g., carborundum) , it will be quite fragile.  Is your setup rigid enough?  I recommended diamond as I thought carbide tipped HSS was unlikely to be that small and solid carbide would be too fragile.  Diamond embedded HSS or even carbon steel would be much more forgiving.  Be sure to keep it wet.

[mendip_discovery]

I would look at getting some reamers. They are designed for making precise holes. A drill bit hole is looked at closely is more of a triangle than round. A reamer is 5 flutes and often are tapered and will just finish off the hole and make it just right.

Sorry… reaming alumina?!?

Not aluminum. Alumina, i.e. aluminum oxide, which is so hard it’s commonly used as an abrasive.

A drill for this is actually just a diamond grinder.

Ok, ya got me there. But you can get diamond-tipped reamers.

Normal carbide reamers can be found on the bay for not a lot. I pick them up for specific hole sizes I like, at the moment its for the 3D printer.