PCB cutting/stamping

Thread Starter

Liako

Joined Nov 9, 2020
8
Hello,
I am Liako, 23y old and new to the Forum.

I have some pcbs which are scratched, so you can break them easily out of the mounting.

I am thinking of creating a more or less automated system, by using either a 3D printed fixture, so cut in a straight line or applying pressure on the knife, so it splits.

My question is, whether it is worth spending time on designing a fixture for my pcbs? Do you have experience with cutting or stamping pcbs? Do you have different ideas?

I´ll appreciate all anwers.

Greeting
Liako :)
 

jpanhalt

Joined Jan 18, 2008
11,088
Welcome to AAC.

I cut my PCB's with a cheap shear designed and sold for cutting non-ceramic floor tiles. Would work well with pre-scored PCB's too.
 

Thread Starter

Liako

Joined Nov 9, 2020
8
Welcome to AAC.

I cut my PCB's with a cheap shear designed and sold for cutting non-ceramic floor tiles. Would work well with pre-scored PCB's too.

Hi jpanhalt,

the struggle I have are the components placed on the pcb. They are very close to the edge to the scretch, so the precision should be really high when cutting or stamping the pcb.

I considerd the principe of the Guillotine.

Liako
 

jpanhalt

Joined Jan 18, 2008
11,088
The cutter I describe is a modified guillotine. You are cutting before adding components, right? If you need an accurate edge or anything other than straight, consider milling the edge. Even easier to to buy cut to size.

I also find a disk sander or belt sander helpful for final dimension and to get a smooth edge..
 

atferrari

Joined Jan 6, 2004
4,248
I am thinking of creating a more or less automated system, by using either a 3D printed fixture, so cut in a straight line or applying pressure on the knife, so it splits.

My question is, whether it is worth spending time on designing a fixture for my pcbs? Do you have experience with cutting or stamping pcbs? Do you have different ideas?
Most of amateurs do produce one or eventually two PCB's and then move to another project so they are far from needing a great number of the same board.

Usually, I do not suggest videos but this one is definitely enlightening and could be inspiring you on the subject. (This engineer BTW, has very interesting videos and is an example of what a video needs to be for explaining technical matters ).

I tried to get a small circular saw (table size) just for cutting PCBs but down here it is impossible. The option suggested by John would be my second choice. Designing one, is a waste of time (if automated - no matter what that could be) I would prefer a coil winding machine instead.
 

Tonyr1084

Joined Sep 24, 2015
5,828
@atferrari Nice video.

As a micro section technician (6 years) I used a wet diamond saw. The blade alone was (back then) $270.00 (U.S.) and certainly not the method recommended for home hobbies. Actually, MY method of cutting PCB's is to carefully score a straight line on both sides where I want to break the board, then nip off the tip of my box cutter blade, leaving a sharp square edge on the tip of the blade. Then drag that down the score line over and over until I've worked my way thought the board. Then, when close to being fully cut down I go ahead and snap the board. Using an old pair of side cutters (Dykes) I can wedge the cut line open and not have to cut fully through a piece of perf board. That way I can cut out a 1" square out of a 2" x 3" stock without wasting any material. It's slow, but it works.

As for cutting a board after population - you always put your components at risk when doing that. Unless you have a cutting rig designed for cutting PCB's apart. It has also been my experience that boards mass produced may have wings (or tabs) on the side to give the machinery something to hold on to without getting too close to components. Those wings are often pre-scored by the board house, meaning there's already a score line that can be snapped. Cutting the boards produces a cleaner edge and saves time not having to clean up those otherwise ragged edges.
 

Thread Starter

Liako

Joined Nov 9, 2020
8
You are cutting before adding components, right?
I have pcbs, with added components. It is also fragil and has some big components like an antenna on the edge. One side I am willing to break by hand. Both sides are pre-scored by the board house and it also has some wings as Tonyr1084 mentioned.

Those wings are often pre-scored by the board house, meaning there's already a score line that can be snapped.
I have many boards which I have to break, that is why I am looking for a solution, without using side cutters. On the board there are 12 pcb each, assembled with components, which I want to break out all at once. By the way, it is rigid-flex.

Greetings
Liako
 

jpanhalt

Joined Jan 18, 2008
11,088
Flexing a PCB can break components, such as surface mounted capacitors and resistors, even IC's. If there are no surface mounted components, the risk is considerably less.

Snapping a scored line bends the PCB a little. Even a guillotine shear causes some flexing, and you need to be able to hold the PCB very firmly to keep it from twisting.
Use judgement.

If I had a fragile PCB with components installed, I would use power (belt or disk) sanding for dimensioning. Nippers, as described above, also work and do not cause much distortion. I would finish the final edge with sanding. Some people use files, but PCB's dull files, and files are much more expensive than sandpaper to replace.
 

johnshaw

Joined Nov 5, 2020
5
Most of amateurs do produce one or eventually two PCB's and then move to another project so they are far from needing a great number of the same board.

Usually, I do not suggest videos but this one is definitely enlightening and could be inspiring you on the subject. (This engineer BTW, has very interesting videos and is an example of what a video needs to be for explaining technical matters ).

I tried to get a small circular saw (table size) just for cutting PCBs but down here it is impossible. The option suggested by John would be my second choice. Designing one, is a waste of time (if automated - no matter what that could be) I would prefer a coil winding machine instead.
Thanks for sharing this video. It helped me a lot.
 
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atferrari

Joined Jan 6, 2004
4,248
Thanks

Thanks for sharing this video. It helped me a lot.
Cutting a lot of small pieces of PCB material, using Manhattan style , I recently built this. It is a 1.2 MHz BJT oscillator

Clapp 1.2 MHz BJT.jpg

If you are interested, here is the thread

Not intending to derail this thread, I will refrain myself of posting here again. Promise.
 

jpanhalt

Joined Jan 18, 2008
11,088
@MrSalts
The TS also said,
I have pcbs, with added components. It is also fragil and has some big components like an antenna on the edge. One side I am willing to break by hand.
For fragile components, my advice still applies. Every shear I have seen involves some curl, even if it is just from release of stress. Nippers are just very small shears. It would be nice to see a picture.
 

MrSalts

Joined Apr 2, 2020
198
@MrSalts
The TS also said,


For fragile components, my advice still applies. Every shear I have seen involves some curl, even if it is just from release of stress. Nippers are just very small shears. It would be nice to see a picture.
My point was, you completely didn't understand what a flex-rigid PCB I hope you do now.
 

Tonyr1084

Joined Sep 24, 2015
5,828
I am looking for a solution, without using side cutters.
Why are you opposed to side cutters? I mean, is there a good reason for that? I find it a good way to separate the board along the grain of the glass fibers and it doesn't add much stress to the board at all.
Nippers, as described above, also work and do not cause much distortion. I would finish the final edge with sanding.
Yes, sanding after nipping. But be careful with sanding dust - as it becomes airborne it can become hazardous to your lungs.
 

mcardoso

Joined May 19, 2020
193
I want to throw this out there. A small milling cutter on a manual (or CNC) mill will do a very clean cut edge. As good as the panel shops. If you have a local maker space or a buddy with a garage shop, then that would be the option I would go for.
 

Tonyr1084

Joined Sep 24, 2015
5,828
A Dremel with a diamond cutting blade can cut PCB's nicely. The tiny wheel is not all that expensive. However, again I must mention the dust factor.

Dremel Power Tool
(about $50.00 U.S.)
Dremel Diamond Blade (about $20.00 U.S.)
There are other diamond blades and accessories available as well.
Here are some other blade options:
 
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jpanhalt

Joined Jan 18, 2008
11,088
Why are you opposed to side cutters? I mean, is there a good reason for that? I find it a good way to separate the board along the grain of the glass fibers and it doesn't add much stress to the board at all.
Yes, sanding after nipping. But be careful with sanding dust - as it becomes airborne it can become hazardous to your lungs.
It does not cause any disease more than a nuisance dust does. The particles are too big. No more precautions are indicated than with any other nuisance dust..
 

Tonyr1084

Joined Sep 24, 2015
5,828
It does not cause any disease more than a nuisance dust does.
While this may be true, the dust from an FR4 board is largely fiberglass and resin. Some people may be sensitive to that. Nevertheless, here's a board I recently cut after population. This is the left-over part. It was cut by scoring along the perf holes and then taking an older blade and nipping the tip off and then dragging it along the score lines to cut (estimating) about 25% through the board from both sides, then using an older pair of side cutters (nippers) I cracked the cut (at #12 and "P") and worked the fracture all the way through to the corner. There's plenty of board left for another project when something small is needed.

1605103827897.png
 
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