How to prevent others from copying your PCB board?

I read the article "How to Copy the Board" today, and now let's talk about "How to Prevent Copying":

1. Grinding the chip, use fine sandpaper to grind off the model on the chip. It is more effective for the chip with partial door;

2. Seal the glue. Use the glue that solidifies into a solid to cover all the pcb and the components on it. You can also deliberately make five or six flying wires (it is better to use thin enameled wires) to twist together, so that the copying The process of dismantling the glue will inevitably break the flying wire and do not know how to connect it. It should be noted that the glue cannot be corrosive, and the heat generated in the closed area is small;

3. Use a dedicated encryption chip;

4. Use unbreakable chips, but there is a cost to pay; 5. Use MASKIC, generally speaking, MASKIC is much harder to crack than programmable chips; MASK (mask): The single-chip microcomputer mask means that the program data has been lithography version, the program is made in the process of single-chip production. The main point is: the program is reliable and low cost. Disadvantages: The batch requirements are large, the lithography needs to be re-made every time the program is modified, different programs cannot be produced at the same time, and the supply cycle is long.

6. Using bare chips, thieves can't see the model or know the wiring. But the function of the chip should not be too easy to guess, it is better to decorate other things in the black glue, such as small ICs, resistors, etc.;

7. Connect a resistance of more than 60 ohms in series on the signal line with low current (so that the on-off gear of the multimeter does not sound);

8. Use some small components without words (or only some code names) to participate in signal processing, such as small chip capacitors, TO-XX *** tubes, three *** tubes, small chips with three to six feet, etc. ;

9. Cross some addresses and data lines (except RAM, and then change them back in the software);

10. The pcb adopts buried hole and blind hole technology, so that the via hole is hidden in the board. This method is expensive, only suitable for products, and increases the difficulty of copying the board;

11. Use other special customized accessories;

12. To apply for a patent, in view of the poor environment for intellectual property protection, foreign methods can only be placed in the latter category.

Last but not least, any measures can only delay the time of committing the crime, and cannot prevent copying. Only by finding our own strengths, forming a technological breaking point, and being able to open source bravely, can we become a great company like Google.