Drill bits for making Vias?

[ejaf]

To All...

I remember in this forum someone mentioning that they get the drill bits required for drilling holes and Vias on PCBs from EBay, but for the life of me I can't seem to find the info now doing a search...

Just exactly what type of bits are needed? Are they carbide? And what are the standard sizes needed? There a lot of "micro" bits on EBay, but I'd hate to buy 50 of the wrong size/type. :eek:

TIA...Eric

[jeffs555]

There really are no standard sizes. For thru hole components like IC's something between 28 and 32 mils is about right. You could use the same for vias.

The bits for commercial drilling of PC boards are carbide, because the fiberglass will dull a drill bit quickly. I believe many of those 50 piece "micro" bits you see on ebay are resharpened bits from PCB operations.

The problem with small carbide bits is that they are brittle and will break easily if you don't have a good small drill press. If you have a local hobby shop, they might have some small numbered drill bits in HSS. Number #67 is 32 mils, and number #70 is 28 mils. HSS should be ok unless you are doing an awful lot of holes.

[ejaf]

great...thanks for the input.

E

[jeffs555]

I do have some of those 50 piece carbide assortments, and they do come in handy. I got mine at a local Harbor Freight, so I could pick one that had a good assortment of sizes. Some of them weren't very assorted. Like I said, the only problem is breaking them. It seems like I snap a bit every other time I try it with the dremel without using the drill press.

[ejaf]

ahhhh...my next question rolls into that answer...The Dremel Drill Press attachment is stable enough to use these carbide bits? I have an XPR 400, and am thinking about getting the press (don't know how I've lived soooo long without it ;) ).

E

[jeffs555]

I don't have one, but I would imagine that it would work fine. You need to make sure you don't put any sideways force on the small carbide bits, and that dremel press looks like it would do the job. I chuck a collet holder in my full size drill press. The higher speed of the dremel works better, but since I don't have the dremel press I try to avoid using the tiny carbide bits with the dremel.

[westfw]

I generally stick with about three sizes of drills. 0.6mm (about .024 inch or #73) for
vias, 0.8mm (about 1/32 inch, 0.031 inch, or #68) for most component and IC leads,
and somewhere around 1.2mm (0.046) for those 0.025 inch square posts on connectors.
Search eBay for "carbide pcb" and you'll get hits. Also here: http://tinkers-emporium.com/

[ejaf]

Ouch...just ordered some, but they start at .8mm.

Vias at .6mm? Is that a standard? Or can they be larger? Is it a function of what you use to fill them?

E

[jeffs555]

The main reason for smaller vias is that you can make a more compact layout. Unless you are concerned with getting the absolute smallest board possible, via size really doesn't matter.

[ejaf]

Got it.

Unless you want to squeeze it down smaller, any size is OK...probably will pick a size that suits what I'm filling it with.

Thanks.

E

[westfw]

I don't see anything wrong with using 0.8mm for vias rather than 0.6, other than the slightly more compact layout. One reason I do it is that it makes the vias visually distinguishable from the component lead holes.

[FlyH2O]

Eric

I have a Dremel drill press and use it to drill PC boards using carbide bits, that is the main reason I got it. If you go to Harbor Freight you will find they sell a ten pack of assorted carbide bits, if you pick through the packages you can find a couple of packs with sizes you need. .032, .050, and .063 are pretty common in the packs. Hope this helps!

Larry O

[ejaf]

yup...that helps...

Starting out with this stuff, so I need all the help I can get :o

Eric

[mmprestine]

ahhhh...my next question rolls into that answer...The Dremel Drill Press attachment is stable enough to use these carbide bits? I have an XPR 400, and am thinking about getting the press (don't know how I've lived soooo long without it ;) ).

E

I would just go to harbor frieght and get one of the $39 drill presses. It is what I have and it works great for drilling PCBs. You have to watch but they go on sale like every other week.

HF drill press (http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=38119)