I'm learning Kicad and I wonder if it's possible to create a SMT circuit that can prevent plagiarism, for example, using more layers in a way that the added wires will be passing above and bellow each other, thus making it harder for someone to know all of the wires connections, thus making it difficult for them copy my design. Maybe this could be achieved only with only a 4 or 6 layers design, but I wonder if that's possible with a 2 layers design.

 

Why are you concerned with copying?

 

I'm learning Kicad and I wonder if it's possible to create a SMT circuit that can prevent plagiarism, for example, using more layers in a way that the added wires will be passing above and bellow each other, thus making it harder for someone to know all of the wires connections, thus making it difficult for them copy my design. Maybe this could be achieved only with only a 4 or 6 layers design, but I wonder if that's possible with a 2 layers design.

No, it is not. People are surprisingly creative and have machines to deconstruct what you've made. Even the layers on integrated circuits can be deconstructed in the layers of silicon. Don't waste your time.

 

There are some things that you can do to make copying circuits more difficult, such as:
1) Remove identifying marks from components;
2) minimize signals going into and out of the circuit;
3) cast the entire circuit, including both sides of the PC board with a very hard epoxy. This is not foolproof but discourages some; and
4) Do not use a printed circuit board - just pot the circuitry as an "air circuit" which should make reverse-engineering more difficult that if it were laid out on a circuit board.

Use all factory-supported anti-copying features on programmable devices.

Nothing in impervious to a highly motivated "pirate", especially those with nothing else do to with their time is to try and crack your circuit.

 

How many of these boards do you expect to sell and for what price? No one is going to go through the effort to copy a board unless it is outrageously profitable.

The easiest way to protect your IP is to do most of the work in a microcontroller and use its copy protection.

 

I heard an apocryphal story about a company that made fruit machines (one armed bandits). They had trouble with competitors copying their boards, so they placed a via what was not a via. It had tracks to it on both sides of the board, but no through-connection. The software was normally set to payout at 96%, but it if found a connection at the via, increased the payout to 104%

 

For the benefit of @spikespiegelbebop , who might not know the term “fruit machine” Ian0 referred to a slot machine used in gamboling.

https://www.ubuy.co.th/en/product/1...iW-QIVhdeWCh1PcwKAEAkYASABEgIXYfD_BwE#gallery

 

Thanks @DickCappels, but actually what I'd like to see is a sample of the design he talked about...

 

You are not going to stop state level clones like we see in China. Personally I like buying products that have schematics and PCB diagrams and actively disqualify products that overtly make repair and understanding the circuit operation at the board level difficult.
https://ieeexplore.ieee.org/document/7820117
PCB Reverse Engineering Using Nondestructive X-ray Tomography and Advanced Image Processing

 

There are some things that you can do to make copying circuits more difficult, such as:

Additionally you can place all of the SMT resistors upside down so the numbers are not visible

 

@MrSalts @nsaspook @BobTPH No, the people that I'm talking about are too ignorant and lazy to get to that level of expertise, it's not like they're going to use x-ray machines to see through the PCB, they're too cheap for that, but they're still greedy, specially the ones from the hobbyists groups that I'm part of. The ones from the groups already have access to the project and its original design (something that I made possible), and since some of them are going to receive my prototype, I don't want them to copy the design that I made by myself, that would be outrageous, because they didn't lift a finger to help me with anything, but they're still demanding me to show the entire thing done.

 

@MrSalts @nsaspook @BobTPH No, the people that I'm talking about are too ignorant and lazy to get to that level of expertise, it's not like they're going to use x-ray machines to see through the PCB, they're too cheap for that, but they're still greedy, specially the ones from the hobbyists groups that I'm part of. The ones from the groups already have access to the project and its original design (something that I made possible), and since some of them are going to receive my prototype, I don't want them to copy the design that I made by myself, that would be outrageous, because they didn't lift a finger to help me with anything, but they're still demanding me to show the entire thing done.

WOW, seems you need better 'friends'.

 

From their behavior, they're more like co-workers.

 

I see many people copy someone's design and then tout it as their own on their blog or worse yet, sell it.
If your device has an MCU then use S/W strategies to thwart cloning it. Example STM32 T12 clone soldering stations, it stores a key in EEPROM to copy protect them. The russians already cracked it and have a key gen, but in china imagine getting the firmware load and ripping off other manufacturers - this is what they try to prevent.
Hardware copy protection is difficult, I've never seen it work beyond installing a silicon serial number IC on the board. More and more MCU's have security built-in. Such as Device ID, secure memory addresses.

 

You could always add a lot of extra parts that actually do nothing and show them that one. (But when you make your own, just use the parts needed.) Then, when they copy one for themselves, it costs them way more to build than the real one. It does not stop them copying it, but you have some satisfaction in knowing it is expensive.
But code protecting the micro is the best way. Let them make the things from your design but sell them the pre-programmed and protected micro they will need. Then you can make money and they do all the build work. Make their copying a feature, not a problem.

 

Using an "air circuit" (aka Manhatten style) construction followed by a sand-filled epoxy will make reverse engineering very difficult. Of course it also makes the device non-repairable, which tells buyers that the product is not worth repairing. So it is a tradeoff. Actuually, building it on a single-side PCB with jumper wires instead of traces on the board, and then encapsulating it with hard sand-mixed epoxy will make tracing the circuit much more difficult Also, put the copper traces on the component side of the board instead of the opposite side. AND, instead of just one resistor, use several in series. That will make the epoxy removal analysis more difficult as well. In fact, use opaque PCB material and don't use thru-holes, simple with SMT parts. For ICs, just bend the pins out and solder in place.