Using KiCAD, making very small PCBs. Many vendors will not make 5mm x 4mm PCBs. My temporary work around is to make 100 boards on one PCB and cut them apart myself. I first tried “V” notch but the assembly house refused to work with V notches. Then I tried making “crackers” but the PCB house and the assembly house would not work with them. I make the boards with corner holds just to align my saw blade. I have 1.5mm spacing for the saw blade.
I have the assembled boards and tried cutting them apart. With a powdered Coping Saw we went through 3 blades to get 100 little boards. (very thin blade)
I may reorder boards with more space between the boards then use my mill to separate the boards. Or I have a good band saw but it eats 3mm between boards.
How do you cut PCBs? Saw or mill? What blades or bits? I have a sander that removes the saw marks and cleans up the edges. Do you know anyone that makes very small boards?
I think this should work better (less delamination) on small/thin boards rather than larger ones. Given your board size, trying it should not cost you much if you do not like the results. Sometimes a board is small enough so that I can save money by putting several on one “board” and then I cut them myself.
I have never machined PCB material in any quantities that approached “production” volume. Any cutting, drilling, shaping, etc, has been a one-off effort for demonstration or prototype units, or modifying a handful of boards (no more than a dozen) so that an order could be shipped before a modified PCB design was received from a PCB fabricator.
Based on those experiences . . . . 5mm x 4mm sounds too small to be done safely! Even if I don’t need my fingers, my wife has many uses for them!
I would approach your problem by first conceding that some material - at least a millimeter; probably two, or even three - will be lost as a “machining allowance”. A scroll saw (like your photo) or a jig saw can cut PCB material. A few incarnations ago, my employer had a commercial table that let you mount a jigsaw under the table, in an inverted position. It worked well for cutting PCB material to size - you could set fences, stops, miter heads, etc to guide the cuts. There are at least dozens, perhaps hundreds, of blade styles available for jigsaws and scrollsaws - different tooth pitches and geometries, etc. There may be a few blade styles specifically intended for cutting fiberglass sheet stock - what styles have you tried?
If dimensional accuracy or quality of the edge finish are important, I’d cut the boards oversize and then trim to size using a piloted flush-trim bit in a woodworking router. Machine a metal template to the finished dimensions, temporarily attach your boards using double-sided “carpet tape” (or similar) and let the router bit’s pilot bearing ride against the template.
I have had good results using a sheet metal shear to cut PCB material, but I don’t recall any pieces as small as 4 or 5 mm. Perhaps a local HVAC shop has the experience to make it work. An old-fashioned office paper cutter - the kind with a heavy metal (or hardwood) bed, and a pivoted, knife-edge, cutting arm - is a poor-man’s substitute for the sheet metal shear. With a little muscle and a good karate yell it’ll work on 0.063" (1.6mm) board stock. But once again, your small dimensions don’t encourage optimism.
PCB dust is nasty stuff and you should try and avoid inhaling it and, as you have found, it wrecks tools. Have you considered a wet tile saw? I’ve never tried this but have heard it being useful.
5x4 mm?
If you use 0.6mm pcb you can use a shear to cut them apart, but that’s not good for assembled boards.
My dad does that… also with thicker prototyping boards before assembly. They are flexible enough to not tear apart too much by this.
If you have access to some local engineering shop (or are in possession of mill/lathe) you could build your own V-groove system to cut the boards apart.
It’s just two sharp wheels like they have them in copper tube pipe cutters aligned so they oppose each other and you feed the board through there. No dust. No wear. Just pressure.
The abrasivity of the pcb (and their nastiness) comes from the glass fibers in them.
TCT tooling is needed to have any chance (tungsten carbide).
Still, the dust is very unhealthy and requires more than your standard painters dust mask to make sure you are safe.
A bandsaw that eats 3mm of the PCB???
It’s unusual for a bandsaw to be that wide. It’s more understandable for a circular saw. Circular saws have carbide teeth that last relatively long, but are very agressive and therefore good jigs to hold your PCB’s are mandatory. One of the problems with circular saws is the gap between the saw and the table. This should get you going: https://www.youtube.com/results?search_query=circular+saw+zero+clearance+insert
You apparently have a lot of these PCB’s.
Cost optimisation probably goes into the direction of reducing manual labour, and not in reducing “wasted” PCB material.
With such small PCB’s you want to separate them as late as possible.
This probably means designing a panel with lots of them and then have at least two sides of each PCB routed during manufacturing.
Maybe you can work with “mouse bites” in your panel. If those are acceptable you can break out the PCB’s from the panel without extra tools.
Maybe you can have all 4 sides routed during PCB manufacturing and only hold the PCB’s by their corners in the panel.
Maybe a “depaneling tool” like the picture below is useful
These tools are designed to be the width of a routing bit, and the goal is to have most of the PCB routed during manufacturing, but leave some small bridges intact, and such a plier cuts those bridges out of the PCB on both sides at the same time. These may be available with a foot pedal, so you have both hands free for manipulating the PCB. These pliers seem adequate for small batches, but for large volumes you probably want more automatisation.
But there are too many variables to give good advise.
How important are straight edges on all sides?
What thickness of PCB’s do you use?
How many of these PCB’s do you need? (elaborate jigs for quicker production?
What are your tolerances?
Components on one or on two sides? (Single sided is easier to cut on a circular table saw)
When your PCB’s get that small there is also not much need for FR4. Maybe FR2 is acceptable, and it’s much easier to cut.
What I’m using is not adapted to production, but In the past, I made 1000 small circuits like this. As a comparison, a 1 cent (euro cent) coin. If you look carefully to the bottom right corner, it’s not perfect, but still a lot better than a V cut.
The board was made on a 100 x 100 board, and I have cut the PCB using a CNC machine with a tungsten (??) carbide tool (3mm). 7 x 7 pieces. The circuit is 10 x 10 mm, and if you add 3 mm for
the router cut, you get 13. 7 x 13 = 91 + a border to hold the whole system.
Cutting speed was the maximal speed I can reach: 40 000 rpm. An with 20 panels, I got 980 boards.
This is already better quality than you can expect from the cheap manufacturers who gladly send you 1000 routed boards with a few dollars. They almost always have some small bumps somewhere.
roboya Love your little boards. I will order 3mm Carbide bits for the mill. Will have to hand run the mill (not CNC). I did not leave 3mm but the board cost is low so another run is fine.
davidsrsb Not FR4, interesting. I may get much thinner boards and have less dust and wear on the bits. [John_Pateman] My hair is turning white from the dust, or maybe age.
paulvdh Straight edges; The boards need to fit into something but not tight. A little slop on the sides is fine. I have 1mm of room between the copper for a through hole connector and the plastic housing. If I nick the pads it will be ok. I used 1.6mm boards but will order 1/2 that next time. Components on one side. This is why I think I can cut the boards. (font went large and bold, don’t see why)
Because I hate soldering R0402 resistors, I had the parts put on the board before separating them. This limits what I can do. I think the shear will brake the little resistors. Next order I may get half the boards with out parts and try more ideas.
Some one said “wet saw”. I do have a table saw for cutting rock floor tile. I think it will eat up 3 to 4mm. I will go out now and try it on a junk board.
The big fat font is probably due to two hash tags “#” and “#” next to each other.
This forum has all kind of formatting tricks with such tokens.
If your PCB’s just have to fit nicely into some enclosure and don’t have to look nice then the easiest way is to use mousebites. They can be offset a bit inside the edge of the PCB so you have room for some jagged edges that do not stick out or interfere with mounting the PCB.
SMT resistors and capacitors are brittle and break easily. There are guidelines for edge-distance for V-grooving, but that won’t work on such a small PCB. So check where your PCB has the most bending stress when breaking / sawing / cutting and move those ceramic things as far from there as feasible. They are also much stronger in the width then in the length, so rotating them 90 degree may also help.
I am using jlcpcb and friends to make these. The guide lines are being violated in many places.
One option is to make the boards 20x20mm (their smallest) and then cut the boards here.
I use a table top disk sander to get the edges of the board right. There is a silk screen line that is to be just removed by the sander. Most PCB houses want distance from copper to edge of board and I need less so sanding seem to be a non violent way to remove 1mm.
I spent two days getting jlcpcb to say I could use a row of non plated holds (like mouse bites) to guide my saw. Then the next day I sent the files and the new person rejected the files. “You are panelizing a too small board. 20x20 is smallest.” So I removed most of the holes and ordered the boards. (board is smaller than the recommended mouse byte)
I need to ship 300 boards by month end. Each board has different parts.
That’s what you get when you go for the cheapest manufacturer.
If you pay normal prices, you can get a lot more service and can even help you with designing your panel.
Those chinese shops are extremely cheap for small quantities in a standard process, but if numbers get bigger and the process less standard (such as 4-layer) then the price difference is much smaller.
I usually use a 0.7mm End-Mill bit (sometimes 0.6mm) for better accuracy, versus a V-Bit.
Using CopperCam to generate the Gcode. CopperCam as a ‘Tab’ feature that user places. Sometimes I place Tabs in Kicad by drawing them in the Edge_Cut layer.
Example below shows both; Tabs on Edge-Cuts layer and Tabs done in CopperCam
I cut them using a Blade from a Hacksaw (thin blade with fine teeth)
I have also used both End-Mill and V-bits to cut to cut them. If I needed to do many, I would use the Mill, not the blade.
Years ago, I used a fab house - they did it with a mill but, I suspect these days, a Laser might be used…
EDIT FreeCad has a ‘Path’ workbench for CNC. Works great and user can place Tabs and set the Tab’s thickness as well a width. Thickness setting thins the tab/PCB height as desired so they can Snap Off easily.
Yes, agree. Locally I can get the smallest board they will make for $33 each + shipping in about 1 week. Then I have to add the parts myself. (they will not make this little board) I could panel them up and pay $33 for 10 and I need to cut them up myself. Then there is a +$50.00 charge for panels. Then $300.00 to have the resistors added. (set up fee)
I went to China and I got 10 boards which each contain 100 little boards with parts on the board for $47.68 including DHL fastest in 8 days. (1000 boards)
In Chine (assuming I can cut the boards apart) $0.05 each. The difference in price will pay for a low end CNC router and a box if bits.
This is my favorite brand and I’ve tested many others. These do a great job and seem to have better ‘tool’ mfg control of dim’s.
Link is for 0.8mm (I never break these but have broken 0.7mm).
Recently, I bought this cheap CNC Mill for fun and to put in office - haven’t used the real mill in garage since LOL! The video in the link shows using V-bit then, End_Mill bit at the end of vid…
I just tried a 1.6mm bit, the smallest I have, and the cuts look good just too wide. The 0.8mm carbide bits are coming from Amazon.
Have not decided about the CNC machine. Have concerns about software. Because my cuts are simple, is there a way to manually position the head over a spot and simply say “down, go north 20cm and stop”?
