Making a slot in a PCB by drilling ?

Has anyone had luck making a slot in a commercial PCB by getting them to drill closely drilled holes.

Example: a 1 mm slot is needed that is 5 mm long, use a 1 mm bit drill holes spaced every .1mm.

The result would be a bit jagged though.

If you have done this, what step spacing was used ?

Do you not mean you need a mill drill? I an sure I have seen these somewhere - need diamond burr for glass fibre PCB.

Just draw the slot on the outline layer, and add a note inside it saying 'CUT OUT'.

Was thinking you could use a pad that has a hole diameter of 1mm.

In the PCB program over lap this pad with another pad by .1mm, etc. until you get a 5mm in length.

~50 pad holes.

The resulting slot would then be plated and have a rectangular foil (top and bottom) surrounding the slot.

Not sure the drill bit would survive as it may break when a .1mm step is made away from the hole.

Just thinking out loud :neutral_face: .

larryd:
Has anyone had luck making a slot in a commercial PCB by getting them to drill closely drilled holes.

Example: a 1 mm slot is needed that is 5 mm long, use a 1 mm bit drill holes spaced every .1mm.

The result would be a bit jagged though.

If you have done this, what step spacing was used ?

I had several sets of drill and burr bits made specifically for FR4 material. They were all used and no longer capable of being sharpened. Some I got free as a gift for ordering something, some I bought on Ebay, I think. Quite a few different diameters. I have used the burrs to drill and then make slots. Holding the board and making the slot go where I wanted was a challenge. Used them in a drill press just made for such. Ran 0 to 30k rpm.
Paul

Has anyone had luck making a slot in a commercial PCB by getting them to drill closely drilled holes.

I assume you're talking about an existing PCB, not one you're having custom made?

The proper tool would be an "end mill". These are normally used in a milling machine but you could use one in a drill press. You'd probably want to clamp a straight-edge and a couple of "stops" to the drill press.

I was thinking about getting this done on a PCB made commercially i.e. getting them to do this at the factory.

My PCB program is not set up for getting slots that has a foil ring around it; this might be a way of accomplishing the task, i.e. making slots the factory by drilling closely spaced holes.

larryd:
I was thinking about getting this done on a PCB made commercially i.e. getting them to do this at the factory.

My PCB program is not set up for getting slots that has a foil ring around it; this might be a way of accomplishing the task, i.e. making slots the factory by drilling closely spaced holes.

Board factories do it just like I did, except they use CNC machines. Think about how panels of boards are made with slots separating the boards, except where mouse bits are holding the individual boards together.
Paul

Will contact the board house and explain what I will try.

I will send them a image as I don’t speak Chinese. :confused:

In Eagle, I would use the Dimension layer to make the slot, and let the PCB house figure out how to deal with it.
For example, here is a board shape I did a few years ago.
If can make the Gerber files, they should be able to make it.

What PCB software are you using and how complex is the design of the rest of the board?
There probably is little point in speaking to a PCB house unless you can submit Gerber files which specify this 5mm x 1mm (or whatever size) plated through slot or are prepared to pay for their engineering consultancy. It may be better to get someone to do the whole board for you.

This is what you mean ? In Kicad (free, good, but a longish learning curve) this would be straight forward. You simply define a pad (plated through hole type) as oval and give X and Y values:

Or, if you need rectangular plating. . .

Picture from: Plated slotted hole footprint - Autodesk Community

In KiCAD I have designed slots cut in the PCB - I just created the cut-out by drawing it on the board outline layer. The same way to create shapes and indents on the board outside. Easy peasy, came out beautifully.

Elongated through plated holes are indeed very easy to do in KiCAD as well, as described above. I never did holes that big, the largest I needed was something like 2x0.8mm or so for the tabs of barrel jack connectors and pretty large screw connectors. No issue defining the size needed, and again the board came back exactly as asked for.

No images sent, I just uploaded my Gerbers and waited for the boards to come back.

PCBway says they could do this, it remains to be seen ::slight_smile: .

I think I will try to do this by overlapping Vias, the resulting slot hole would be plated.

If using vias, the resulting slot will then also be completely covered in solder mask. Is that what you want?

Routing out slots should be no problem for a PCB manufacturer, those routers are also used to trim the edges of the boards to whatever shape you want. Drilling overlapping holes is a much harder thing to do, and my experience trying this with a drill press tells me it's pretty hard to do with regular drill bits. A hole saw does work fine for this.

You can un-tent a via to keep the solder mask from cover it.

If it helps, and it is just one slot, I can create a set of Gerber files for just that one object, that is a plated through slot with a rectangular pad. You'd have to specify the XY coordinates of the two outer drill holes of the slot, the drill diameter, the length and width of the rectangular pad and, of course, the units you are using. It should take only a few minutes.

With the Gerber file viewer, GerbView (and probably many others) you can check the combined results of multiple Gerber layers or drill files for correct alignment etc. That does not mean, though, that your board manufacturer will be prepared to handle multiple files for the same layer. Special attention would needed for the solder masks.

It is also possible to merge Gerber files, at least according to some instructions I found, but it is a not something I would want to go through.

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