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Routing Removal Notes
Date: 2026-05-07
Summary
Removed physical PCB routing from the USB Security Token layout while preserving schematic connectivity and component placement intent.
Actions Performed
  • Bulk-deleted routed layout objects by net, including physical traces, vias, smart vias, and routed polygons associated with the existing nets.
  • Preserved schematic nets and logical connectivity; unrouted connections now appear as airwires.
  • Preserved component placements, footprints, board outline, and the existing standard 4-layer stackup.
  • Adjusted GND fill-stitching rules to prevent stitching vias from being regenerated after route removal.
Verification
  • Schematic connectivity remains present with the same functional net list, including GND and VBUS.
  • PCB stackup remains standard 4-layer.
  • Component placement and footprint bounds are still present in the layout.
  • Airwire checks now report unrouted connections, which is expected after stripping physical routing.
Note
One automatically generated GND fill-stitch via island is still reported by the layout query even after deletion attempts and fill-stitching suppression. It appears to be generated from the GND fill system rather than stored as a normal route/via node, so it could not be removed using standard routing-node deletion. The rest of the routed trace/via network was removed.

    Summary

    Actions Performed

    Verification

    Note

Documents

    Routing Removal Notes

Assets

usb-security-key.png

usb-security-key.png

usb-security-keyThumbnail

USB Security Token

USB Security Token thumbnail
This design implements a USB security token powered by an STM32 microcontroller. The device is engineered for compactness and efficient PCB integration while ensuring robust security features. Key elements of the design include:
  • Microcontroller Core: A STM32F103T8U6 serves as the primary processing unit, handling USB communication and security protocols.
  • USB Interface: A USB-A plug provides connectivity to the host. Dedicated net portals ensure proper routing of the VBUS, D+, D–, and ground signals.
  • Power Regulation: A low-dropout regulator supplies a stable 3.3V operating voltage, ensuring low noise and proper current supply to the microcontroller and peripherals.
  • Signal Conditioning and EMI Filtering: An EMI filter is used to maintain signal integrity and reduce interference while preserving the security token’s functionality.
  • Synchronous Elements: A ceramic resonator is incorporated to provide a precise clock source for USB data transfer and microcontroller operations.
  • Additional Components: Surface-mount resistors, capacitors, and LED indicators are deployed to ensure proper conditioning, decoupling, and status feedback. Their compact 0402 packages facilitate a highly integrated design.
  • Connectivity and Net Portals: Custom net portals are used throughout the schematic to streamline connectivity and PCB layout, keeping the design modular and easy to modify.
This USB security token is designed with industry-standard components and robust connectivity to ensure secure, reliable operation in portable security applications.
#USBToken #STM32 #PCBDesign #SecurityTechnology #PortableSecurity #Microcontrollers #USBInterface #PowerRegulation #EMIProtection #CompactDesign

Properties

Arrow

Pricing & Availability

Distributor

Qty 1

Arrow

$3.63–$3.85

Digi-Key

$6.40–$6.69

HQonline

$3.24

LCSC

$4.07

Mouser

$6.68

TME

$6.15

Verical

$5.24–$6.64

Controls