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If you mean cutting into a copper clad board, for hobby or prototype stuff, which no doubt you don't, but anyway, I find a cutter (/exacto knife I think it's called in the USA) is a good choice. New blades dig into the copper/board and can stick; once a blade segment is old/used a fair bit, the cuts between tracks become sloppier and marginally wider due to the lack of sharpness and precision. It is uncomfortable after a couple of hours if it is rectangular. You could use any strong enough arts and crafts scalpel-style knives as well, and that might be more comfortable to hold for long periods, especially those with plastic handles/stems.
If you mean cutting into a copper clad board, for hobby or prototype stuff, which no doubt you don't, but anyway, I find a cutter (/exacto knife I think it's called in the USA) is a good choice. New blades dig into the copper/board and can stick; once a blade segment is old/used a fair bit, the cuts between tracks become sloppier and marginally wider due to the lack of sharpness and precision. It is uncomfortable after a couple of hours if it is rectangular. You could use any strong enough arts and crafts scalpel-style knives as well, and that might be more comfortable to hold for long periods, especially those with plastic handles/stems.
If you expect to cut a microstrip by hand, the inaccuracies are going to be so great that you shouldn't even bother. There's no way you're going to be able to cut, say, a 14 mil trace.
https://www.eeweb.com/tools/microstrip-impedance using this calculator, I am using an FR4 board: H = 1.5mm, T = 0.05mm, W = 2.7mm, and Er = 4.7.... So, I want to cut the coppers width at about 2.7mm in width (not 14 mil). I am trying to design my own 2.4 GHz LNA with this, on https://www.farnell.com/datasheets/1644697.pdf it says Er = 4.7 at 1 GHz, but Im guessing Er isn't going to be much of a significance since I am working at 2.4 GHz?
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https://www.eeweb.com/tools/microstrip-impedance using this calculator, I am using an FR4 board: H = 1.5mm, T = 0.05mm, W = 2.7mm, and Er = 4.7.... So, I want to cut the coppers width at about 2.7mm using adhesive copper tape.
I have been cutting away larger copper areas in prototypes sometimes. For peeling off the copper from the PCB carrier, heat from hot air soldering station helps a lot.
I have never had any luck cutting "soft" substrates, such are rogers duroid. The dielectric material is so soft that the knife dents into it more than cutting.
FR4 boards, being very stiff, can easily be cut. I use an Exacto knife with a stout handle and the big blade.
I cut the area i do not want copper on, then use a soldering iron tip set at very hot to heat up the copper, and it peals away easily. Put the board on a non slip surface so it does not move....i just use my antistatic rubber mat top on the workbench.
Watch your fingers, as you have to put a lot of force on the knife.
To cut FR4 board for prototyping, i use a sheet metal shear:
it is also handy for cutting copper sheet, for forming horns, antennas, emi shields, etc.
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it is going to be a crude circuit, but often that is all you need to do a simple circuit function during a prototype system test. Some random circuits i had lying around:
Note the one with the pre-printed protoboard squares...i use those a LOT for circuits that have plastic packed SMT devices, like amplifiers.
For cutting traces in an existing PCB do I also use an exacto but with a blade where I have intentionally broken the tip at a sharp angle. That makes it possible to create traces using knife as a chisel and avoids creating a trench in CU layer as it else easily becomes with a knife.
If prototyping a complete board do I remove all copper at top layer and creates new traces with CU-tape which is easy to cut with a scissor to needed width before applied at PCB.
It is then also easy to increase trace width by replacing whole trace with a new strip CU-tape.
I am assuming you mean "all unused copper at the top layer". Normally it does not matter if you leave unused metal on the top.
But i have seen cases where that extra metal forms a parallel plate resonator with the ground plane underneath, and causes havoc. In those cases, you drill a hole thru the board in a few places, and run a copper wire from top to back, and solder it to both sides. that will "short out" the resonator, and keep things happy.
BTW, when you try to drill small holes in a PC board, EXPECT the drill to break. So WEAR SAFETY GLASSES, and have lots of standby drills. I buy big boxes of re-sharpened carbide drills the PC board houses use and throw away, just for this purpose.
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