1, grinding, grinding the model on the chip with fine sandpaper. For chips with partial doors, it is more useful. For commonly used chips, it is easy for reverse engineers to compare the real chips by guessing a general function and checking the grounding and power supply of those pins.
2. Glue sealing, that is, use the solidified stone-like glue (such as the one that sticks steel and ceramics) to cover the PCB and all the components on it. Five or six flying wires (preferably with thin enameled wires) can be deliberately twisted together, so that thieves will inevitably break the flying wires and do not know how to connect them during the process of removing the glue. It should be noted that the glue cannot be corrosive and the heat in the closed area is not too great.
3. It costs only a few dollars to use a special encryption chip, such as AT88SC153 of ATMEL. As long as the software can't be disassembled, thieves can't copy all the signals even if they intercept them with a logic analyzer.
4. Use unbreakable chips, such as EPLD's EPM7128 or above, ACTEL's CPLD, etc., but the cost is high (more than 1 yuan), which is not suitable for small products.
5. using MASK IC, generally speaking, MASK IC is much more difficult to crack than programmable chips, which requires a lot of batches. MASK is not only to MCU, but also includes ROM, FPGA and other special chips.
6. With bare chips, thieves can't see the model and don't know the wiring. But the function of the chip should not be too easy to guess. It is best to decorate other things in that vinyl, such as small IC and resistor.
7. Connect a resistor of more than 6 ohms in series on the signal line with low current (so that the on-off gear of the multimeter will not ring), which will cause great trouble for the reverse operator when measuring the connection relationship with the multimeter.
8. Many small components without words (or only symbols) are used to participate in signal processing, such as small patch capacitors, TO-XX diodes, triodes, small chips with three to six pins, etc. It is still a bit troublesome to find out its true face.
9. Cross some addresses and data lines (except the RAM, the corresponding cross is required in the software), so that those who are in reverse can't be lazy when measuring the connection relationship by analogy.
1. PCB adopts buried hole and blind hole technology to hide the via hole in the board. This method is expensive and only suitable for high-end products.
11. Use other special accessories, such as customized LCD screen, customized transformer, SIM card, encrypted disk, etc.
12. Apply for a patent. In view of the poor environment of intellectual property protection, the most preferred method abroad can only be put in the last one here.