A Chip-PCB Hybrid SC PUF Used for Anti-Desoldering and Depackaging-Attack Protection

By sensing and changing the parasitic capacitance mismatch of chip pads, bumps or bonding wires, package substrate and balls, and printed circuit board (PCB) solder joints and traces into on-chip keys, the proposed chip-PCB hybrid switched-capacitor (SC) physical unclonable function (PUF) can detect the capacitance alteration caused by damaging of the package or removing of the chip from the original PCB, thereby achieving the anti-desoldering and depackaging-attack protection for the security chip. Moreover, the IO ports used for connecting the PCB traces can be shared with other normal communication function blocks, which can realize full use of IO resources while not increasing the package cost. The proposed chip-PCB hybrid SC PUF is verified in security chips by using different processes, including the traditional 28-nm CMOS process and the advanced 14- and 7-nm FinFET CMOS processes. The change of chip-PCB hybrid SC PUF’s output key when the bump of the chip is removed, or the chip is desoldered from the original PCB verifies the anti-desoldering and depackaging-attack properties of the proposed chip-PCB hybrid SC PUF. With the help of chip-PCB hybrid SC PUF, the comprehensive protection of the overall hardware environment for both the chip and the PCB hardware systems can be realized.